Professor Klaus Moessner


Professor in Cognitive Networks
PhD, MSc, Dipl.-Ing. (FH), SMIEEE
+44 (0)1483 683468
05 CII 01
walk-in: Friday 13:00-14:00, otherwise on appointment.

Biography

In the media

IET workshop “5G State of Play”
Speaking on “5G and the factories of the future”
IET tv
IET workshop “Towards 5G Mobile Technology – Vision to reality”
Speaking about “Dynamic Resource Allocation in 5G”
IET tv
Media Contacts

Contact the press team

Email:

mediarelations@surrey.ac.uk

Phone: +44 (0)1483 684380 / 688914 / 684378
Out-of-hours: +44 (0)7773 479911
Senate House, University of Surrey
Guildford, Surrey GU2 7XH

Research

Research interests

Research projects

My teaching

Supervision

Postgraduate research supervision

My publications

Publications

Arshad K, Briggs K, Moessner K (2011) Robust spectrum sensing for cognitive radio based on statistical tests, Proceedings of the 4th International Conference on Cognitive Radio and Advanced Spectrum Management ACM
Spectrum sensing, in particular, detecting the presence of incumbent users in licensed spectrum, is one of the pivotal task for cognitive radios (CRs). In this paper, we provide solutions to the spectrum sensing problem by using statistical test theory, and thus derive novel spectrum sensing approaches. We apply the classical Kolmogorov-Smirnov (KS) test to the problem of spectrum sensing under the assumption that the noise probability distribution is known. In practice, the exact noise distribution is unknown, so a sensing method for Gaussian noise with unknown noise power is proposed. Next it is shown that the proposed sensing scheme is asymptotically robust and can be applied to non-Gaussian noise distributions. We compare the performance of sensing algorithms with the well-known Energy Detector (ED) and Anderson-Darling (AD) sensing proposed in recent literature. Our paper shows that proposed sensing methods outperform both ED and AD based sensing especially for the most important case when the received Signal to Noise Ratio (SNR) is low.
Vural S, Wei D, Moessner K (2012) Survey of Experimental Evaluation Studies for Wireless Mesh Network Deployments in Urban Areas Towards Ubiquitous Internet, IEEE Communications Surveys and Tutorials PP (99) pp. 1-17 IEEE
Establishing wireless networks in urban areas that can provide ubiquitous Internet access to end-users is a central part of the efforts towards defining the Internet of the future. In recent years, Wireless Mesh Network (WMN) backbone infrastructures are proposed as a cost effective technology to provide city-wide Internet access. Studies that evaluate the performance of city-wide mesh network deployments via experiments provide essential information on various challenges of building them. In this survey, we particularly focus on such studies and provide brief conclusions on the problems, benefits, and future research directions of city-wide WMNs.
Akhtar N, Moessner K (2008) Capacity of grid-oriented wireless mesh networks, 2008 3RD INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEM SOFTWARE AND MIDDLEWARE AND WORKSHOPS, VOLS 1 AND 2 pp. 631-636 IEEE
Moessner K, Bourse D, El-Khazen K, Grandblaise D (2004) The responsibility chain in end-to end reconfigurable systems, Proc. and the Symp Mobile Future Trends in Communications. SympoTIC ?04. Joint IST Workshop pp. 208-211
Durowju O, Arshad K, Moessner K (2011) Cognitive time variant power control in slow fading mobile channels, IEEE Vehicular Technology Conference
Increased spectrum efficiency has been demonstrated with the use of cognitive radios, however with increased likelihood of interference to the incumbents of spectrum. Several studies solved the interference problem from the transmitter power control perspective, so as to curtail excessive cognitive interference powers; however, neglecting the effect of secondary terminal mobility. We show by simulation that such assumption of terminal immobility in the power control algorithm would fail in time variant cases resulting in increased levels of interference to the Incumbents as well as serious degradation in QoS within the cognitive radio network. We model the link gain evolution process as a distance dependent shadow fading process and scale up the target signal to interference ratio to cope with time variability. This paper therefore, proposes a mobility driven power control algorithm for cognitive radios based on sensing information, which ensures that the interference limit at the Incumbents is unperturbed at all times while concurrently maintaining the QoS within the cognitive radio network. © 2011 IEEE.
Durowoju O, Arshad K, Moessner K (2011) Distributed power control algorithm for cognitive radios with primary protection via spectrum sensing under user mobility, Ad Hoc Networks 10 (5) pp. 740-751 Elsevier
Substantial spectrum gains have been demonstrated with the introduction of cognitive radio however; such gains are usually short lived due to the increased level of interference to licensed users of the spectrum. The interference management problem is herein tackled from the transmitter power control perspective so that transmissions by cognitive radio network does not violate the interference threshold levels at the primary users as well as maintain the QoS requirements of cognitive radio users. We model the cognitive radio network for mobile and immobile users and propose algorithms exploiting primary radio environment knowledge (spectrum use), called power control with primary protection via spectrum sensing. The algorithm is briefly introduced for time invariant systems and demonstrated that it has the ability to satisfy tight QoS constraints for cognitive radios as well as meet the interference constraints for licensed users. We, however, further show that such assumption of terminal immobility in the power control algorithm would fail in cases where user mobility is considered, resulting in increased levels of interference to the primary as well as increased outages in cognitive radio network. We model the link gain evolution process as a distance dependent shadow fading process and scale-up the target signal to interference ratio to cope with user mobility. Since mobility driven power control algorithms for cognitive radios have not been investigated before, we therefore, propose a mobility driven power control framework for cognitive radios based on spectrum sensing, which ensures that the interference limit at the primary receiver is unperturbed at all times, while concurrently maintaining the QoS within the cognitive radio network as compared to static user cases. We also corroborate our algorithms with proof of convergence.
Reetz ES, Kuemper D, Moessner K, Tonjes R (2013) How to test IoT-based services before deploying them into real world, 19th European Wireless Conference, EW 2013
Efficient testing of Internet of Things (IoT)-based services suffers from the underlying heterogeneous nature of IoT resources and hinders the process of rapid service creation and deployment. Real world effects, based on the behaviour of IoT-based services, tend to prevent the straight forward execution within the productive environment. Current solutions for testbeds, involving physical or virtual IoT resources, appear to require intense capacities for time and resources. This paper describes a new approach for testing IoT-based service build on a code insertion methodology, which can be derived from the semantic description of the IoT-based service. The proposed IoT resource emulation interface is described from the semantic, architectural and implementation perspective. The paper compares its applicability and efficiency with classical approaches and expose high emulation capabilities while minimising the testing effort. © VDE VERLAG GMBH.
De S, Moessner K (2009) A Framework for Mobile, Context-Aware Applications, 2009 INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT) pp. 232-237 IEEE
Arshad K, Moessner K (2010) Mobility driven energy detection based spectrum sensing framework of a cognitive radio, Proceedings - 2010 2nd UK-India-IDRC International Workshop on Cognitive Wireless Systems, UKIWCWS 2010
A cognitive radio opportunistically accesses spectrum bands under the constrain that it does not interfere with the licensed users. Cognitive radio performs spectrum sensing to find spectrum opportunities. Although a large number of spectrum sensing algorithms are available in literature; majority of them addressed static cognitive radios. In this paper, we study the energy detection based local spectrum sensing in the presence of user mobility. We show that CR mobility improves spectrum sensing performance by exploiting spatial diversity. We propose a framework for local spectrum sensing in which a cognitive radio do multiple spectrum measurements and makes a decision about the existence of the licensed user. An optimal fusion rule based on likelihood ratios is derived and based on test statistics a suitable detector and functional architecture of a cognitive radio is proposed. A closed form expression for the number of spectrum measurement cycles is also derived in this paper under given performance constraints. ©2010 IEEE.
Arshad K, Moessner K (2013) Robust spectrum sensing based on statistical tests, IET Communications 7 (9) pp. 808-817
Spectrum sensing, in particular, detecting the presence of licensed or incumbent users in licensed spectrum, is one of the pivotal tasks in cognitive radio network. In this study, the authors tackle the spectrum sensing problem by using statistical test theory and derive novel spectrum sensing approaches. The authors apply the classical Kolmogorov-Smirnov (KS) test under the assumption that the noise probability distribution is known. However, as in practice, the exact noise distribution is unknown, a sensing method for Gaussian noise with unknown noise power is proposed in this article and referred to t-sensing. The proposed sensing scheme is asymptotically robust and can be applied to non-Gaussian noise distributions. A closed form equation determining the miss-detection probability for the t-sensing is derived. The authors compare with the performance of our sensing algorithms with the energy detector and Anderson-Darling (AD) sensing methods proposed in literature. Simulation results show that the proposed sensing methods outperform both ED- and AD-based sensing, especially for the case when the received signal-to-noise ratio is low. © The Institution of Engineering and Technology 2013.
Marques P, Rodriguez J, Delaere S, Gundlach M, Triantafyllopoulou D, Moessner K, Delahaye P, Lecroart B, Noguet D (2013) Shared use of radio spectrum in the EU: from research projects to standards, pp. 1249-1254
This paper addresses the current regulatory framework, main research activities and standardization efforts towards a shared use of radio spectrum in the European Union. A survey of emerging spectrum sharing applications and associated standardization paths is described. Remaining challenges for an effective participation of research projects in Cognitive Radio standards are discussed. A new coordination action funded by the European Commission that aims to boost standardization impact of research projects working of cognitive radio and spectrum sharing aspects is presented.
Durowoju O, Arshad K, Moessner K (2010) Distributed Power Control for Cognitive Radios with Primary Protection via Spectrum Sensing, Proc. IEEE 72nd Vehicular Technology Conf. Fall (VTC 2010-Fall) pp. 1-5
Attou A, Moessner K (2007) Context-aware service adaptation management, 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9 pp. 1468-1472 IEEE
Georgiades M, Moessner K, Dagiuklas T (2008) On the enhancement of mobility and multimedia communications in heterogeneous RANs, International Journal of Internet Protocol Technology 3 (1) pp. 22-34
Lee H, Vahid S, Moessner K (2014) A sub-optimal channel switching-aware spectrum aggregation approach for CRNs, Proceedings of the 2014 9th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2014 pp. 114-119
We consider a cognitive radio network (CRN) that intends to opportunistically aggregate and utilize spectrum of a primary network to achieve higher data rates. In such an opportunistic spectrum access, primary user can reclaim a channel used by a secondary transmission. When the secondary transmission is interrupted by a primary transmission, the secondary network needs to switch the channel of the interrupted transmission, resulting in additional delay. When a secondary user accesses more spectrum to increase its data rate, channel switching could be more frequent. In this context, we formulate a dynamic spectrum aggregation optimisation problem to minimize channel switching delay. While considering multiple users, the problem is formulated as a sum of fractional programming problems. We propose a sub-optimal algorithm that simplifies the fractional programming to linear programming first and solves each linear programming (for each user) using Dinkelbach's algorithm. Simulation results demonstrate that the proposed algorithm can reduce the channel switching delay. When multiple users are served in the network, the proposed algorithm also shows good performance in terms of fairness and total data transmission time. © 2014 ICST.
To improve inter-operability of future 5G systems
with existing technologies, this paper proposes a novel context-aware
user-driven framework for network selection in multi-
RAT environments. It relies on fuzzy logic to cope with the
lack of information usually associated with the terminal side
and the intrinsic randomness of the radio environment. In
particular, a fuzzy logic controller first estimates the out-of-context
suitability of each RAT to support the QoS requirements
of a set of heterogeneous applications. Then, a fuzzy multiple
attribute decision making (MADM) methodology is developed
to combine these estimates with the various components of the
context (e.g., terminal capabilities, user preferences and operator
policies) to derive the in-context suitability level of each RAT.
Based on this novel metric, two spectrum selection and spectrum
mobility functionalities are developed to select the best RAT
in a given context. The proposed fuzzy MADM approach is
validated in a dense small cell environment to perform a context-aware
offloading for a mixture of delay-sensitive and best-effort
applications. The results reveal that the fuzzy logic component
is able to efficiently track changes in the operating conditions
of the different RATs, while the MADM component enables to
implement an adjustable context-aware strategy. The proposed
fuzzy MADM approach results in a significant improvement in
achieving the target strategy, while maintaining an acceptable
QoS level compared to a traditional offloading based on signal
strength.
Kernchen R, Meissner S, Moessner K, Cesar P, Vaishnavi I, Boussard M, Hesselman C (2010) Intelligent Multimedia Presentation in Ubiquitous Multidevice Scenarios, IEEE MULTIMEDIA 17 (2) pp. 52-62 IEEE COMPUTER SOC
This intelligent multimedia adaptation and delivery framework tailors to ubiquitous environments, so that users can experience multimedia content using multiple devices in various mobility situations.
Bantouna, A, Stavroulaki V, Kritikou Y, Tsagkaris K, Demestichas P, Moessner K (2012) An overview of learning mechanisms for cognitive systems, EURASIP Journal on Wireless Communications and Networking 2012 2012 (22) Springer
Cognitive systems were first introduced by Mitola and in the last decade they have proved to be beneficial in self-management functionalities of future generation networks. The advantages and the way that networks gain benefits from cognitive systems is analysed in this article. Moreover, since such systems are closely related to machine learning, the focus of this article is also placed on machine learning techniques applied both in the network and the user devices side. In particular, celebrating 10 years of cognitive systems, this survey-oriented article presents an extended state-of-the-art of machine learning applied to cognitive systems as coming from the recent research and an overview of three different learning capabilities of both the network and the user device.
Triantafyllopoulou D, Guo T, Moessner K (2014) Energy-Efficient WLAN Offloading through Network Discovery Period Optimization, IEEE Transactions on Vehicular Technology 64 (6)
In this paper we present an analytical framework to improve the energy consumption of mobile nodes through traffic offloading via Wireless Local Area Networks (WLANs), taking into account the energy consumption for both data transmission and network discovery operations. More specifically, we formulate an optimization problem, according to which the network scanning period is optimized in order to minimize the total energy consumption and the energy consumption per transmitted bit in a scenario where a user moves with a constant, either pedestrian or vehicular, speed along a road covered by a long range cellular network and a number of randomly deployed WLANs. The performance of the system that employs the proposed framework, which uses information on the user speed as well as on the availability and the load level of neighboring networks and performs periodic network scanning with the optimal period, is compared against a sub-optimal system that does not take into consideration the user and network context information when determining the network scanning period. According to performance evaluation results, the use of the optimal network scanning period achieves significant improvement in terms of total energy consumption, energy efficiency and network detection delay.
Georgoulas S, Ghader M, Moessner K, Dianati M, Tafazolli R (2011) On the applicability of architecture description languages to future internet networking environments,
Architecture Description Languages enable the formalization of the architecture of systems and the execution of preliminary analysis on them, aiming at the identification and resolution of design problems in the early stages of development. Such problems can be incompatibilities and mismatches in the connections between system components and in the format and type of information exchanged between them. Architecture Description Languages were initially developed to validate the correctness of software architectures; however, their applicability has been extended to cover many diverse areas during the past few years. In this paper, we aim to show how Architecture Description Languages can be applied to and be a useful tool towards validating the correctness of architectures and configurations of future internet networking environments. We do so by using a recently proposed architectural approach and a recently proposed deployment approach, implemented by means of network virtualization, as case studies
Moessner K, Harada H, Sun C, Alemseged Y, Tran H, Noguet D, Sawai R, Sato N (2011) Spectrum sensing for cognitive radio systems: Technical aspects and standardization activities of the IEEE P1900.6 working group, IEEE Wireless Communications 18 (1) pp. 30-37
Liu X, Evans BG, Moessner K (2015) Energy-efficient sensor scheduling algorithm in cognitive radio networks employing heterogeneous sensors, IEEE Transactions on Vehicular Technology 64 (3) pp. 1243-1249
© 2013 IEEE.We consider, in this paper, the maximization of throughput in a dense network of collaborative cognitive radio (CR) sensors with limited energy supply. In our case, the sensors are mixed varieties (heterogeneous) and are battery powered. We propose an ant colony-based energy-efficient sensor scheduling algorithm (ACO-ESSP) to optimally schedule the activities of the sensors to provide the required sensing performance and increase the overall secondary system throughput. The proposed algorithm is an improved version of the conventional ant colony optimization (ACO) algorithm, specifically tailored to the formulated sensor scheduling problem. We also use a more realistic sensor energy consumption model and consider CR networks employing heterogeneous sensors (CRNHSs). Simulations demonstrate that our approach improves the system throughput efficiently and effectively compared with other algorithms.
Alnwaimi G, Arshad K, Moessner K (2011) Dynamic spectrum allocation algorithm with interference management in co-existing networks, IEEE Communications Letters 15 (9) pp. 932-934
This work addresses analytically the impact of multi-cell, multi-operator interference on the overall radio resources when multiple operators co-exist and share a common pool of spectrum. We propose a centralised dynamic spectrum allocation (DSA) scheme that is able to measure the interference level and interact dynamically to minimise interference and enhance spectrum utilisation while maintaining a satisfactory level of QoS. Furthermore, a concise system model and framework able to describe the interaction among different operators is presented. © 2011 IEEE.
Moessner K, Gultchev S, Tafazolli R (2001) Software defined radio reconfiguration management, Proc. 12th IEEE Int Personal, Indoor and Mobile Radio Communications Symp 1
De S, Zhou Y, Moessner K (2016) Real world city event extraction from Twitter data streams, Procedia Computer Science 98 pp. 443-448
The immediacy of social media messages means that it can act as a rich and timely source of real world event information. The detected events can provide a context to observations made by other city information sources such as fixed sensor installations and contribute to building ?city intelligence?. In this work, we propose a novel unsupervised method to extract real world events that may impact city services such as traffic, public transport, public safety etc., from Twitter streams. We also develop a named entity recognition model to obtain the precise location of the related events and provide a qualitative estimation of the impact of the detected events. We apply our developed approach to a real world dataset of tweets collected from the city of London.
Jiang J, Pozza R, Gunnarsdottir K, Gilbert GN, Moessner K (2017) Recognising Activities at Home: Digital and Human Sensors, Proceedings of ICFNDS ?17, Cambridge, United Kingdom, July 19-20, 2017 ACM, the Association for Computing Machinery
What activities take place at home? When do they occur, for how
long do they last and who is involved? Asking such questions is
important in social research on households, e.g., to study energyrelated
practices, assisted living arrangements and various aspects
of family and home life. Common ways of seeking the answers
rest on self-reporting which is provoked by researchers (interviews,
questionnaires, surveys) or non-provoked (time use diaries). Longitudinal
observations are also common, but all of these methods
are expensive and time-consuming for both the participants and
the researchers. The advances of digital sensors may provide an
alternative. For example, temperature, humidity and light sensors
report on the physical environment where activities occur, while
energy monitors report information on the electrical devices that
are used to assist the activities. Using sensor-generated data for
the purposes of activity recognition is potentially a very powerful
means to study activities at home. However, how can we quantify
the agreement between what we detect in sensor-generated
data and what we know from self-reported data, especially nonprovoked
data? To give a partial answer, we conduct a trial in a
household in which we collect data from a suite of sensors, as well
as from a time use diary completed by one of the two occupants.
For activity recognition using sensor-generated data, we investigate
the application of mean shift clustering and change points
detection for constructing features that are used to train a Hidden
Markov Model. Furthermore, we propose a method for agreement
evaluation between the activities detected in the sensor data and
that reported by the participants based on the Levenshtein distance.
Finally, we analyse the use of different features for recognising
different types of activities.
De S, Moessner K (2008) Ontology based context inference and query for mobile devices, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC
-The VISIon of service personalization for mobile communication environments entails context sensitive service
provisioning. The realization of such customizable smart spaces necessitates acquisition and processing of modality context information from a variety of devices in the ambient
environment. The heterogeneity of available device capabilities and description formats brings new challenges for a context reasoning engine that formulates content delivery decisions. Specifically, to ensure interoperability with existing application logic, the enabling components should support semantic queries.
Secondly, situations where variously formatted context input may not provide enough information to answer queries, should be intelligently handled. Towards this aim, this paper discusses a context reasoning and query interface component as part of a Service Context Manager (SCM) framework that supports semantic querying and handles incomplete context information through a rule-based mechanism. The validation of the approach is provided by showing the mapping of disparate UAProf and UPnP descriptions into the framework and querying of supported modality services.
Zhou Y, De S, Wang W, Moessner K, Palaniswami M (2017) Spatial Indexing for Data Searching in Mobile
Sensing Environments,
Sensors MDPI
Data searching and retrieval is one of the fundamental functionalities in many Web of
Things applications, which need to collect, process and analyze huge amounts of sensor stream data.
The problem in fact has been well studied for data generated by sensors that are installed at fixed
locations; however, challenges emerge along with the popularity of opportunistic sensing applications
in which mobile sensors keep reporting observation and measurement data at variable intervals and
changing geographical locations. To address these challenges, we develop the Geohash-Grid Tree,
a spatial indexing technique specially designed for searching data integrated from heterogeneous
sources in a mobile sensing environment. Results of the experiments on a real-world dataset collected
from the SmartSantander smart city testbed show that the index structure allows efficient search
based on spatial distance, range and time windows in a large time series database.
Oredope A, Moessner K, Peoples C, Parr G (2013) Deploying cloud services in mobile networks, Proceedings of 2013 Science and Information Conference, SAI 2013 pp. 928-933
Mobile networks have gone through various stages of evolution with each stage aimed at addressing a wide range of challenges and limitations. During the early evolutions of mobile networks - 2G, 2.5G, 3G -, the key challenge was to investigate efficient and cost effective ways of delivering higher data speeds. This led to the proposals and development of 4G LTE networks based on a flat all-IP architecture with Internet based protocols. However, recent trends indicates that the Internet-like architecture in mobile networks has further enabled Internet based cloud service providers to provide Over-The-Top (OTT) applications to mobile devices bypassing and competing with the mobile operator on services such as voice, video, messaging and gaming. This is a key motivation for cloud service providers and mobile operators to explore various opportunities in which they can both leverage on their existing infrastructures in order to efficiently deploy cloud services in mobile environments. In this paper we study the challenges and limitations that constrains the efficient deployment of cloud services in mobile environments. We then propose a collaborative approach in which the cloud service provider and mobile operator can dynamically manage the underlying mobile network infrastructure resources in order to optimise the delivery of cloud services in mobile environments. This is achieved by using cloud management approaches with the ability to factor in mobile resources such as mobility and frequency spectrums while also integrating the cloud service provider and mobile operator cloud infrastructures © 2013 The Science and Information Organization.
Grandblaise D, Moessner K, Vivier G, Tafazolli R (2007) Credit token based rental protocol for dynamic channel allocation, 1st International Conference on Cognitive Radio Oriented Wireless Networks and Communications 2006, CROWNCOM
This paper describes a distributed, cooperative and real time rental protocol for DCA operations in a multi system and mult) cell context for OFDMA systems. A credit token based rental protocol using auctioning Is proposed in support of dynamic spectrum sharing between cells. The proposed scheme can be tuned adaptively as a function of the context by specifying the credit tokens usage in the radio etiquette. The application of the rental protocol is illustrated with an ascending bid auctioning. The paper also describes two approaches for BS-BS communications in support of the rental protocol. Finally, it is described how the proposed mechanisms contribute to the current approaches followed in the IEEE 802.16h and IEEE 802.22 standards efforts addressing cognitive radio, © 2006 IEEE.
Gürgen L, Biswas AR, Moessner K, Ramparany F (2012) Welcome message from the chairs, Self-IoT'12 - Proceedings of the 2012 International Workshop on Self-Aware Internet of Things, Co-located with ICAC'12
The energy consumption of backbone networks has become a primary concern for network operators and regulators due to the pervasive deployment of wired backbone networks to meet the requirements of bandwidth-hungry applications. While traditional optimization of IGP link weights has been used in IP based load-balancing operations, in this paper we introduce a novel link weight setting algorithm, the Green Load-balancing Algorithm (GLA), which is able to jointly optimize both energy efficiency and load-balancing in backbone networks. Such a scheme can be directly applied on top of existing link sleeping techniques in order to achieve substantially improved energy saving gains. The contribution is a practical solution that opens a new dimension of energy efficiency optimization, but without sacrificing traditional traffic engineering performance in plain IP routing environments. In order to evaluate the efficiency of the proposed optimization scheme without losing generality, we applied it to a set of recently proposed but diverse algorithms for link sleeping operations in the literature. Evaluation results based on the European academic network topology, GÉANT, and its real traffic matrices show that GLA can achieve significantly improved energy efficiency compared to the original standalone algorithms, while also maintaining near-optimal load-balancing performance.
Ghader M, Moessner K, Tafazolli R (2004) Service Discovery and Provision Protocols for Wireless Networks,
Grandblaise D, Kloeck C, Moessner K, Rodriguez V, Mohyeldin E, Pereirasamy MK, Luo J, Martoyo I (2005) Techno - economic of collaborative based secondary spectrum usage - E2R research project outcomes overview, Proc. First IEEE Int. Symp. New Frontiers in Dynamic Spectrum Access Networks DySPAN 2005 pp. 318-327
De S, Moessner K (2008) Semantic Description of Multimodal Devices: Modelling and Evaluation, Collaboration and the Knowledge Economy: Issues, Applications and Case Studies 5 pp. 1439-1446 IOS Press
The heterogeneous, dynamic nature of current communication environments necessitates that all system components that form part of a personalisation framework should be context aware. To ensure context enabled interoperation, a shared, formalised specification of devices and services in the ambient environment is a must. With this aim, this paper presents an ontology model that captures the semantics of the multimodal devices and services in the mobile ad-hoc environment. The approach is validated using available metrics and compared to existing approaches, both through subjective feature-based evaluation and metrics? calculations. This paper also extends the metrics? usability by extending the analysis to interoperability with application logic and domain capture.
Kernchen R, Boda PP, Moessner K, Mrohs B, Boussard M, Giuliani G (2005) Multimodal user interfaces for context-aware mobile applications, Proc. IEEE 16th Int. Symp. Personal, Indoor and Mobile Radio Communications PIMRC 2005 4 pp. 2268-2273
Wang W, De S, Toenjes R, Reetz E, Moessner K (2012) A Comprehensive Ontology for Knowledge Representation in the Internet of Things, pp. 1793-1798 IEEE
Semantic modeling for the Internet of Things has
become fundamental to resolve the problem of
interoperability given the distributed and heterogeneous
nature of the ?Things?. Most of the current research has
primarily focused on devices and resources modeling while
paid less attention on access and utilisation of the
information generated by the things. The idea that things are
able to expose standard service interfaces coincides with the
service oriented computing and more importantly,
represents a scalable means for business services and
applications that need context awareness and intelligence to
access and consume the physical world information. We
present the design of a comprehensive description ontology
for knowledge representation in the domain of Internet of
Things and discuss how it can be used to support tasks such
as service discovery, testing and dynamic composition.
Tehrani RH, Vahid S, Triantafyllopoulou D, Lee H, Moessner K (2016) Licensed Spectrum Sharing Schemes for Mobile Operators: A Survey and Outlook, IEEE Communications Surveys and Tutorials 18 (4)
The ongoing development of mobile communication networks to support a wide range of superfast broadband services has led to massive capacity demand. This problem is expected to be a significant concern during the deployment of the 5G wireless networks. The demand for additional spectrum to accommodate mobile services supporting higher data rates and having lower latency requirements, as well as the need to provide ubiquitous connectivity with the advent of the Internet of Things (IoT) sector, is likely to considerably exceed the supply, based on the current policy of exclusive spectrum allocation to mobile cellular systems. Hence, the imminent spectrum shortage has introduced a new impetus to identify practical solutions to make the most efficient use of the scarce licensed bands in a shared manner. Recently, the concept of dynamic spectrum sharing has received considerable attention from regulatory bodies and governments globally, as it could potentially open new opportunities for mobile operators to exploit spectrum bands whenever they are underutilised by their owners, subject to service level agreements. Although various sharing paradigms have been proposed and discussed, the impact and performance gains of different schemes can be scenario-specific and vary depending on the nature of the sharing parties, the level of sharing and spectrum access scheme. In this survey, we describe the main concepts of dynamic spectrum sharing, different sharing scenarios, as well as the major challenges associated with sharing licensed bands. Finally, we conclude this survey paper with open research challenges and suggest some future research directions.
Alnwaimi G, Vahid S, Moessner K (2015) Dynamic heterogeneous learning games for opportunistic access in LTE-based macro/femtocell deployments, IEEE Transactions on Wireless Communications 14 (4) pp. 2294-2308
© 2002-2012 IEEE.Interference is one of the most limiting factors when trying to achieve high spectral efficiency in the deployment of heterogeneous networks (HNs). In this paper, the HN is modeled as a layer of closed-access LTE femtocells (FCs) overlaid upon an LTE radio access network. Within the context of dynamic learning games, this work proposes a novel heterogeneous multiobjective fully distributed strategy based on a reinforcement learning (RL) model (CODIPAS-HRL) for FC self-configuration/optimization. The self-organization capability enables the FCs to autonomously and opportunistically sense the radio environment using different learning strategies and tune their parameters accordingly, in order to operate under restrictions of avoiding interference to both network tiers and satisfy certain quality-of-service requirements. The proposed model reduces the learning cost associated with each learning strategy. We also study the convergence behavior under different learning rates and derive a new accuracy metric in order to provide comparisons between the different learning strategies. The simulation results show the convergence of the learning model to a solution concept based on satisfaction equilibrium, under the uncertainty of the HN environment. We show that intra/inter-tier interference can be significantly reduced, thus resulting in higher cell throughputs.
Tandur D, Duplicy J, Arshad K, Depierre D, Moessner K, Lehtomaki J, Briggs K, Goncalves L, Gameiro A (2012) COGNITIVE RADIO SYSTEMS EVALUATION Measurement, Modeling, and Emulation Approach, IEEE VEHICULAR TECHNOLOGY MAGAZINE 7 (2) pp. 77-84 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Rostami S, Arshad K, Moessner K (2012) Order-statistic based spectrum sensing for cognitive radio, IEEE Communications Letters 16 (5) pp. 592-595
Spectrum sensing for cognitive radio is challenging. In this letter, a spectrum sensing method based on quintiles of Order-Statistics is proposed. We derive the test statistic and evaluate the performance of the proposed method by Monte Carlo simulations. Simulation results show that order statistics based sensing considerably outperforms both energy detection and anderson darling based sensing in an Additive White Gaussian Noise (AWGN) channel; especially in a lower signal to noise ratio region. © 2012 IEEE.
Zhou Y, De S, Wang W, Moessner K (2014) Enabling Query of Frequently Updated Data from Mobile Sensing Sources, IEEE
The Internet of Things (IoT) paradigm connects everyday objects to the Internet and enables a multitude of applications with the real world data collected from those objects. In the city environment, real world data sources include fixed installations of sensor networks by city authorities as well as mobile sources, such as citizens? smartphones,¬ taxis and buses equipped with sensors. This kind of data varies not only along the temporal but also the spatial axis. For handling such frequently updated, time-stamped and structured data from a large number of heterogeneous sources, this paper presents a data-centric framework that offers a structured substrate for abstracting heterogeneous sensing sources. More importantly, it enables the collection, storage and discovery of observation and measurement data from both static and mobile sensing sources.
Gluhak A, Inoue M, Moessner K, Tafazolli R (2007) Signaling channel for coordinated multicast service delivery in next generation wireless networks, IEICE TRANSACTIONS ON COMMUNICATIONS E90B (7) pp. 1780-1790 IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG
Cassar G, Barnaghi P, Wang W, Moessner K (2012) A hybrid semantic matchmaker for IoT services, Proceedings - 2012 IEEE Int. Conf. on Green Computing and Communications, GreenCom 2012, Conf. on Internet of Things, iThings 2012 and Conf. on Cyber, Physical and Social Computing, CPSCom 2012 pp. 210-216
The use of semantic Web technologies and service oriented computing paradigm in Internet of Things research has recently received significant attention to create a semantic service layer that supports virtualisation of and interaction among "Things". Using service-based solutions will produce a deluge of services that provide access to different data and capabilities exposed by different resources. The heterogeneity of the resources and their service attributes, and dynamicity of mobile environments require efficient solutions that can discover services and match them to the data and capability requirements of different users. Semantic service matchmaking process is the fundamental construct for providing higher level service-oriented functionalities such as service recommendation, composition, and provisioning in Internet of Things. However, scalability of the current approaches in dealing with large number of services and efficiency of logical inference mechanisms in processing huge number of heterogeneous service attributes and metadata are limited. We propose a hybrid semantic service matchmaking method that combines our previous work on probabilistic service matchmaking using latent semantic analysis with a weighted-link analysis based on logical signature matching. The hybrid method can overcome most cases of semantic synonymy in semantic service description which usually presents the biggest challenge for semantic service matchmakers. The results show that the proposed method performs better than existing solutions in terms of precision (P@n) and normalised discounted cumulative gain (NDCGn) measurement values. © 2012 IEEE.
Chantaraskul S, Moessner K (2010) Implementation of a genetic algorithm-based decision making framework for opportunistic radio, IET COMMUNICATIONS 4 (5) pp. 495-506 INST ENGINEERING TECHNOLOGY-IET
Pozza R, Nati M, Georgoulas S, Gluhak A, Moessner K, Krco S (2014) CARD: Context-Aware Resource Discovery for mobile Internet of Things scenarios,
Dimitrakopoulos G, Demestichas P, Tsagkaris K, Saatsakis A, Moessner K, Muck M, Bourse D (2009) Emerging, Self-Management Functionality for Introducing Cognition in the Wireless, B3G World, WIRELESS PERSONAL COMMUNICATIONS 48 (1) pp. 33-47 SPRINGER
Thilakawardana D, Moessner K (2009) Traffic modelling and forecasting using genetic algorithms for next-generation cognitive radio applications, ANNALES DES TELECOMMUNICATIONS-ANNALS OF TELECOMMUNICATIONS 64 (7-8) pp. 535-543 SPRINGER FRANCE
Vlacheas P, Giaffreda R, Stavroulaki V, Kelaidonis D, Foteinos V, Poulios G, Demestichas P, Somov A, Biswas A, Moessner K (2013) Enabling smart cities through a cognitive management framework for the internet of things, IEEE Communications Magazine 51 (6) pp. 102-111
The Internet of Things (IoT) is expected to substantially support sustainable development of future smart cities. This article identifies the main issues that may prevent IoT from playing this crucial role, such as the heterogeneity among connected objects and the unreliable nature of associated services. To solve these issues, a cognitive management framework for IoT is proposed, in which dynamically changing real-world objects are represented in a virtualized environment, and where cognition and proximity are used to select the most relevant objects for the purpose of an application in an intelligent and autonomic way. Part of the framework is instantiated in terms of building blocks and demonstrated through a smart city scenario that horizontally spans several application domains. This preliminary proof of concept reveals the high potential that self-reconfigurable IoT can achieve in the context of smart cities. © 2013 IEEE.
Thilakawardana D, Moessner K (2007) A genetic approach to cell-by-cell dynamic spectrum allocation for optimising spectral efficiency in wireless mobile systems, 2007 2ND INTERNATIONAL CONFERENCE ON COGNITIVE RADIO ORIENTED WIRELESS NETWORKS AND COMMUNICATIONS pp. 367-372 IEEE
Ganz F, Barnaghi P, Carrez F, Moessner K (2011) A mediated gossiping mechanism for large-scale sensor networks, 2011 IEEE GLOBECOM Workshops, GC Wkshps 2011 pp. 405-409
Gateways in sensor networks are used to relay, aggregate and communicate information from capillary networks to more capable (e.g. IP-based) networks. However Gateway-to-Gateway (G2G) communication to exchange and update information among the gateways in large-scale sensor networks for query processing, data fusion and other similar tasks has been less discussed in recent works. The requirements for large-scale sensor networks such as dynamic topology and update strategies to reduce the overall network load makes G2G communications an important aspect in the network design. In this paper, we introduce a mediated gossip-based G2G communication mechanism. The proposed solution leverages the publish/subscribe approach and uses high-level context assigned to publish/subscribe channels to enable the information discovery and G2G communications. Gateways store/aggregate sensor observation and measurement data according to specific context which is defined based on features such as spatial and temporal attributes, observed phenomena (i.e. feature of interest) and sensor device features. The gateways communicate with each other to exchange data and also to forward related queries for data aggregation in cases that the data should be aggregated from two different sources. The proposed solution also facilitates reliable sensor service provisioning by enabling gateways to communicate and/or forward requests to other gateways when a resource fails or a sensor node becomes unavailable. We compare our results to probabilistic gossiping algorithms and run benchmarks on different dynamic network topologies based on indicators such as number of sent messages and dissemination delay. © 2011 IEEE.
Arshad K, Moessner K (2011) Statistical models of spectrum opportunities for cognitive radio, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC pp. 2310-2314
Dynamic Spectrum Access (DSA) is widely seen as a feasible solution to the problem of illusive radio spectrum clogging. The fundamental concept of DSA is to opportunistically access unutilised spectrum bands while respecting the rights of privileged incumbent users. DSA and spectrum policies depend on meticulous statistics of spectrum opportunities as well as spectrum occupancy models. In this paper, we develop a model to characterise the number of spectrum opportunities available using the probability and approximation theory. In particular, we derive the probability mass function (PMF) of the total number of spectrum opportunities available depending on the probability of each channel being free. We further analyse the complexity involved in calculating the PMF of the total number of available channels at any time and location and develop approximate models. Numerical results are provided showing that the proposed approximation models of spectrum opportunities achieve good accuracy at significantly lower computational cost. © 2011 IEEE.
Akbar A, Carrez F, Moessner K, Zoha A (2015) Predicting Complex Events for Pro-Active IoT Applications, 2015 IEEE 2ND WORLD FORUM ON INTERNET OF THINGS (WF-IOT) pp. 327-332 IEEE
Akhtar N, Moessner K (2008) On the nominal capacity of multi-radio multi-channel wireless mesh networks, COMPUTER COMMUNICATIONS 31 (8) pp. 1475-1483 ELSEVIER SCIENCE BV
Arshad K, Moessner K (2011) Efficient spectrum management among spectrum sharing UMTS operators, IEEE Vehicular Technology Conference
Dynamic spectrum management is a promising solution for network operators to efficiently utilise the limited radio spectrum and guarantee operator's profit by increasing capacity as well as generating more spectrum opportunities for opportunistic use. This paper presents a novel algorithm for efficient spectrum management to optimise spectrum utilisation between two sharing UMTS cellular operators. It is shown that proposed solution approach increases revenue of sharing operators without sacrificing the quality of service on either network. A multioperator UMTS simulation tool is also developed to evaluate the performance of proposed algorithm. The simulation results show that the proposed algorithm achieves high efficiency of spectrum utilisation and gains up to 33% can be achieved for both uniform and non-uniform distribution of traffic. © 2011 IEEE.
Stavroulaki V, Bantouna A, Kritikou Y, Tsagkaris K, Demestichas P, Blasco P, Bader F, Dohler M, Denkovski D, Atanasovski V, Gavrilovska L, Moessner K (2012) Knowledge management toolbox: Machine learning for cognitive radio networks, IEEE Vehicular Technology Magazine 7 (2) pp. 91-99
Learning mechanisms are essential for the attainment of experience and knowledge in cognitive radio (CR) systems, exposed to high dynamics with often unpredictable states [1]. These mechanisms can be associated with user and device profiles, context, and decisions. The focus learning user preferences is the dynamic inference and estimation of current and future user preferences. The acquisition and learning of context information encompasses mechanisms for the system to perceive its current status and conditions in its present environment, as well as estimating (and forecasting) the capabilities of available network configurations. Finally, learning related to decisions addresses the building of knowledge with respect to the efficiency of solutions that can be applied to specific situations encountered. Based on knowledge obtained through learning, decision-making mechanisms can become faster, since the CR system can learn and immediately apply solutions that have been identified as being efficient in the past. Moreover, knowledge obtained through learning mechanisms may be shared among nodes of a system. Thus, more reliable and more optimal decisions can be made by exploiting knowledge obtained through learning mechanisms. © 2005-2012 IEEE.
Holland O, Muck M, Martigne P, Bourse D, Cordier P, Jemaa SB, Houze P, Grandblaise D, Klöck C, Renk T, Pan J, Slanina P, Mößner K, Giupponi L, Romero JP, Agusti R, Attar A, Aghvami AH (2007) Development of a Radio enabler for reconfiguration management within the IEEE P1900.4 working group, 2007 2nd IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks pp. 232-239
An important emerging capability is for mobile terminals to be dynamically reconfigured. Through ongoing advances in technology such as software defined radio, reconfiguration of mobile terminals will in the near future be achievable across all layers of the protocol stack. However, along with the capability for such wide-ranging reconfiguration comes the need to manage reconfiguration procedures. This is necessary to coordinate reconfigurations, to ensure that there are no negative effects (e.g. interference to other RATs) as a result of reconfigurations, and to leverage maximal potential benefits of reconfiguration and ensuing technologies such as those involving dynamic spectrum access. The IEEE P1900.4 working group is therefore defining three building blocks for reconfiguration management: Network Reconfiguration Management (NRM), Terminal Reconfiguration Management (TRM), and a radio enabler to provide connectivity between the NRM and TRMs. In this paper we concentrate on aspects of the radio enabler, highlighting its relevance in heterogeneous radio access scenarios, its advantages, and some aspects of its technical realization. © 2007 IEEE.
In this paper we present and evaluate the performance of a resource allocation algorithm to enhance the Quality of Service (QoS) provision and energy efficiency of downlink Orthogonal Frequency Division Multiple Access (OFDMA) systems. The proposed algorithm performs resource allocation using information on the downlink packet delay, the average delay and data rate of past allocations, as well as the downlink users' buffer status in order to minimize packet segmentation. Based on simulation results, the proposed algorithm achieves significant performance improvement in terms of packet timeout rate, goodput, fairness, and average delay. Moreover, the effect of poor QoS provision on energy efficiency is demonstrated through the evaluation of the performance in terms of energy consumption per successfully received bit.
De S, Moessner K (2009) Rule-based Reasoning Mechanism for Context-aware Service Presentation, eChallenges e-2009 Conference Proceedings IIMC International Information Management Corporation Ltd
With universal usability geared towards user focused customisation, a
context reasoning engine can derive meaning from the various context elements and
facilitate decision-taking for applications and context delivery mechanisms. The
heterogeneity of available device capabilities means that the recommendation
algorithm must be in a formal, effective and extensible form. Moreover, user
preferences, capability context and media metadata must be considered
simultaneously to determine appropriate presentation format. Towards this aim, this
paper presents a reasoning mechanism that supports service presentation through a
rule-based mechanism. The validation of the approach is presented through
application use cases.
Cassar G, Barnaghi P, Wang W, De S, Moessner K (2013) Composition of Services in Pervasive Environments: A Divide and Conquer Approach,
Gultchev S, Moessner K, Tafazolli R (2003) Network based reconfiguration support services for software radio terminals, Proc. 3G Mobile Communication Technologies 4th Int. Conf. (Conf. Publ. No. 494) pp. 119-122
Rodriguez J, Marques P, Radwan A, Moessner K, Tafazolli R, Raspopoulos M, Stavrou S, Trapps P, Noquet D, Sithamparanathan K, Gomes A, Piesiewicz R, Mokrani H, Foglar A, Verikoukis C (2010) Cognitive radio and cooperative strategies for power saving in multi-standard wireless devices, 2010 Future Network and Mobile Summit
Energy is a critical resource in the design of wireless networks since wireless devices are usually powered by batteries. Without any new approaches for energy saving, 4G mobile users will relentlessly be searching for power outlets rather than network access, and becoming once again bound to a single location. To avoid the so called 4G "energy trap" and to help wireless devices become more environment friendly, there is a clear need for disruptive strategies to address all aspects of power efficiency from the user devices through to the core infrastructure of the network and how these devices and equipment interact with each other. The ICT-C2POWER project is the vehicle that will address these issues through cognitive techniques and cooperation. The C2POWER case study is to research, develop and demonstrate energy saving technologies for multi-standard wireless mobile devices, exploiting the combination of cognitive radio and cooperative strategies, while still enabling the required performance in terms of data rate and QoS to support active applications. Copyright © 2010 The authors.
Thilakawardana D, Moessner K, Tafazolli R (2008) Darwinian approach for dynamic spectrum allocation in next generation systems, IET COMMUNICATIONS 2 (6) pp. 827-836 INST ENGINEERING TECHNOLOGY-IET
Yu X, Navaratnam P, Moessner K (2012) Distributed Admission Control with Soft Resource Allocation for Hybrid MAC in P2P Wireless Networks, Computer Networks
Rodriguez V, Moessner K, Tafazolli R (2005) Auction driven dynamic spectrum allocation: optimal bidding, pricing and service priorities for multi-rate, multi-class CDMA, Proc. IEEE 16th Int. Symp. Personal, Indoor and Mobile Radio Communications PIMRC 2005 3 pp. 1850-1854
Yu X, Navaratnam P, Moessner K (2011) Delay model for super frame based resource reservation in distributed wireless networks, MobiMedia 2011 - Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2012 79 pp. 89-104 SpringerLink
Ayyadurai V, Moessner K, Tafazolli R (2011) Multihop cellular network optimization using genetic algorithms, 2011 7th International Conference on Network and Service Management
Future cellular systems demand higher throughput as an important requirement, along with smaller cell sizes to characterize the performance of network services. This paper purposes a way to optimize the multihop cellular network (MCN) deployment in LTE-A/Mobile WiMAX broadband wireless access systems. A simple way to optimize the MCN is to associate direct and multihop users based on maximum channel quality and allocate the resources blocks dynamically based on traffic load balancing as adjustment variables. The changing traffic demands require dynamic network reconfiguration to maintain proportional fairness in achieving the throughput. A self optimizing network based on genetic algorithm (GA) is made to adaptively resize the cell coverage limit and dynamically allocate resources based on active user demands. A policy control scheme to control resource allocations between direct and multihop users can be either fixed resource allocation (FRA) or dynamic resource allocation (DRA).
Alnwaimi G, Arshad K, Moessner K (2009) Collaborative spectrum sensing in OFDM-based Cognitive Radio, Proceedings - 2009 1st UK-India International Workshop on Cognitive Wireless Systems, UKIWCWS 2009
Cassar G, Barnaghi P, Wang W, De S, Moessner K (2013) Composition of Services in Pervasive Environments: A Divide and Conquer Approach, IEEE
In pervasive environments, availability and reliability of a service cannot always be guaranteed. In such environments, automatic and dynamic mechanisms are required to compose services or compensate for a service that becomes unavailable during the runtime. Most of the existing works on services composition do not provide sufficient support for automatic service provisioning in pervasive environments. We propose a Divide and Conquer algorithm that can be used at the service runtime to repeatedly divide a service composition request into several simpler sub-requests. The algorithm repeats until for each sub-request we find at least one atomic service that meets the requirements of that sub-request. The identified atomic services can then be used to create a composite service. We discuss the technical details of our approach and show evaluation results based on a set of composite service requests. The results show that our proposed method performs effectively in decomposing a composite service requests to a number of sub-requests and finding and matching service components that can fulfill the service composition request.
Jalili B, Dianati M, Evans BG, Moessner K (2013) Collaborative radio resource allocation for the downlink of multi-cell multi-carrier systems, IET Communications 7 (5) pp. 430-438
This study investigates collaboration among neighbouring base stations for the downlink of multi-carrier cellular networks, in the absence of a centralised control unit, which is a defining characteristic of future wireless networks. The authors propose a novel scheme for collaboration in resource allocation among a cluster of three neighbouring base stations. In this scheme, the results of an initial calculation are shared among neighbouring cells, then the scheduling decision is made locally and independently by each cell. This scheme does not require complex and iterative calculation. The information is exchanged only once during each scheduling epoch, which results in reduced overhead on the backhaul links. The scheme is implemented in a distributed manner. Simulation-based performance analysis demonstrates effectiveness of the proposed collaborative resource allocation scheme among the neighbouring base stations for multi-carrier systems, particularly for the users located near the cell edges. ©The Institution of Engineering and Technology 2013.
Georgoulas S, Moessner K, Mcaleer B, Tafazolli R (2010) Towards efficient protocol design through protocol profiling and verification of performance and operational metrics, Proceedings of the 6th International Wireless Communications and Mobile Computing Conference pp. 848-852
Formal verification tools have been extensively used in the past to assess the correctness of protocols, processes, and systems in general. Their most common use so far has been in identifying whether livelock or deadlock situations can occur during protocol execution, process, or system operation. In this paper we aim to showcase that an additional equally important and useful application of formal verification tools can be in protocol design and optimization itself. This can be achieved by using the tools in a rather different context compared to their traditional use. That is not only as means to assess the correctness of a protocol in terms of lack of livelock and deadlock situations but rather as tools capable of building profiles of protocols, associating performance related metrics, and identifying operational patterns and possible bottleneck operations in terms of metrics of interest. This process can provide protocol designers with an insight about the protocols' behavior and guide them towards further protocol design optimizations. We illustrate these principles using some existing protocol implementations as case studies. Copyright © 2010 ACM.
Francois F, Wang N, Moessner K, Georgoulas S, Xu K (2014) On IGP link weight optimization for joint energy efficiency and load balancing improvement, Computer Communications 50 pp. 130-141
The energy consumption of backbone networks has risen exponentially during the past decade with the advent of various bandwidth-hungry applications. To address this serious issue, network operators are keen to identify new energy-saving techniques to green their networks. Up to this point, the optimization of IGP link weights has only been used for load-balancing operations in IP-based networks. In this paper, we introduce a novel link weight setting algorithm, the Green Load-balancing Algorithm (GLA), which is able to jointly optimize both energy efficiency and load-balancing in backbone networks without any modification to the underlying network protocols. The distinct advantage of GLA is that it can be directly applied on top of existing link-sleeping based Energy-aware Traffic Engineering (ETE) schemes in order to achieve substantially improved energy saving gains, while at the same time maintain traditional traffic engineering objectives. In order to evaluate the performance of GLA without losing generality, we applied the scheme to a number of recently proposed but diverse ETE schemes based on link sleeping operations. Evaluation results based on the European academic network topology GÉANT and its real traffic matrices show that GLA is able to achieve significantly improved energy efficiency compared to the original standalone algorithms, while also achieving near-optimal load-balancing performance. In addition, we further consider end-to-end traffic delay requirements since the optimization of link weights for load-balancing and energy savings may introduce substantially increased traffic delay after link sleeping. In order to solve this issue, we modified the existing ETE schemes to improve their end-to-end traffic delay performance. The evaluation of the modified ETE schemes together with GLA shows that it is still possible to save a significant amount of energy while achieving substantial load-balancing within a given traffic delay constraint. © 2014 Elsevier B.V. All rights reserved.
Chantaraskul S, Moessner K (2010) Experimental study of multi-resolution spectrum opportunity detection using wavelet analysis, 2010 IEEE Symposium on New Frontiers in Dynamic Spectrum, DySPAN 2010
Spectrum sensing is one of the crucial aspects in Cognitive Radio (CR). Fast and accurate spectrum opportunity detection provides interference avoidance to other/licensed users. At the same time, it offers more efficient spectrum utilization by providing accurate sensing information as an input to the intelligent dynamic resource allocation process. Wideband spectrum sensing has been introduced due to the higher bandwidth demand and increasing spectrum scarcity since it provides better chance of detecting spectrum opportunity. In this paper, the application of wavelet transform techniques for wideband spectrum opportunity detection in CRs is documented. Wavelet analysis is used in two-step process detection or multi-resolution opportunity detection proposed here. Edge detection using wavelet analysis is employed in the first step to indentify possibly available subband(s). The fine analysis is done in the second step for each chosen subband(s) using wavelet transform in order to detect any non-stationary signal, which may present in the chosen subband(s). With this two-step process, detection time could be reduced and at the same time providing detection accuracy. The paper presents research approach and the experimental study, which involves the development of the test platform used to obtain real-time spectrum sensing results and the software tool used for the opportunity detection. The experimental results are provided, which prove the practicality and accuracy of the approach. ©2010 IEEE.
Peoples C, Parr G, Oredope A, Moessner K (2013) The standardisation of cloud computing: Trends in the state-of-the-art and management issues for the next generation of cloud, Proceedings of 2013 Science and Information Conference, SAI 2013 pp. 902-911
Roll-out of future cloud systems will be influenced by regulations from the standardisation bodies, if made available across the community. Trends in cloud deployment, operation and management to date have not been guided by any regulatory standards, and resources have been deployed in an ad hoc manner as demanded according to the business objectives of service providers. This is the least costly and most quickly revenue-returning business model. It is not however, the most cost-effective approach on a long-term basis: As a consequence of this roll-out model to date, the interoperability of resources deployed across clouds managed by different operators is restricted through inability to allocate workload to them in a regulated and controllable manner. The absence of standardised approaches to cloud management is therefore beginning to be accommodated such that the cost and performance advantages of interoperable operation may be exploited. In this paper, we review the state-of-the-art in standards across the field and trends in their development. We present a model which defines the drivers for cloud interoperability and constraints which restrict the extent to which this may realistically occur in future scalable solutions. This is supplemented with discussion on future challenges foreseen with regard to cloud operation and the way in which standards require provision such that cloud interoperation may be accommodated. © 2013 The Science and Information Organization.
Zhdanova AV, Li N, Moessner K (2008) Semantic web in ubiquitous mobile communications, pp. 266-287
The world becomes ubiquitous, and mobile communication platforms become oriented towards integration with the web, getting benefits from the large amount of information available there, and creation of the new types of value-added services. Semantic and ontology technologies are seen as being able to advance the seamless integration of the mobile and the Web worlds. We provide background information on the Semantic Web field, discuss other research fields that bring semantics into play for reaching the ontology-enabled ubiquitous mobile communication vision, and exemplify the state of the art of ontology development and use in telecommunication projects. © 2009, IGI Global.
De S, Moessner K (2007) Context gathering in Ubiquitous Environments: Enhanced Service Discovery, 3rd Workshop on Context Awareness for Proactive Systems (CAPS'2007) Proceedings
Delivering individualized services that conform to the user?s current
situation will form the focus of ubiquitous environments. A description of the
networked environment at a semantic level will necessitate contextually
oriented knowledge acquisition methods. This then engenders unique
challenges for the crucial step of resource discovery. A number of service
discovery protocols exist to perform this role. In this paper, we identify the
requirements inherent for such an environment and investigate the suitability of
the available protocols against these. A suitable candidate solution is proposed
with an implementation with semantic extensions and reference points for
further enhancements.
Oredope A, McConnell A, Peoples C, Singh R, Gonsalves TA, Moessner K, Parr GP (2013) Cloud Services in Mobile Environments - The IU-ATC UK-India Mobile Cloud Proxy Function., EW VDE-Verlag
Georgoulas S, Moessner K, Eracleous D, Nati M (2012) Formal Verification of the Cooperative Behaviour of Network Nodes for Routing and Context Dissemination, Future Network & Mobile Summit (FutureNetw), 2012 IEEE
One of the most fundamental forms of cooperation in any network is the cooperation between network nodes for routing and the subsequent context dissemination. To do so each node runs an instance of a routing process relying, in many cases, only on partial network information rather than network-wide information. This can lead to instabilities and problematic situations, such as deadlocks or livelocks. Deadlock is a condition where a process stalls; meaning it reaches a state from which there is no exit action. When it comes to routing this would mean the condition where a packet reaches a node and is not forwarded any further because the routing process has reached a state which was not taken into account in its behavioural specification. Livelock is a condition from where a process can exit; however every exit action will eventually lead the process back to the same condition. With respect to routing this would refer to the existence of loops. In this paper we show how formal verification, and in particular model checking, can be applied in this context; to find such problems and also assess the performance and quantify properties of the overall routing process. As an example case study we use a routing protocol designed for wireless sensor networks named Adaptive Load Balanced Algorithm Rainbow version, suitable for context dissemination in Wireless Sensor Network environments, where energy efficient operations are also important.
Ko Y, Moessner K (2012) Maximum outage capacity in dense indoor femtocell networks with joint energy and spectrum utilization, IEEE Transactions on Wireless Communications 11 (12) pp. 4416-4425
We consider a multiple femtocell deployment in a small area which shares spectrum with the underlaid macrocell. We design a joint energy and radio spectrum scheme which aims not only for co-existence with the macrocell, but also for an energy-efficient implementation of the multi-femtocells. Particularly, aggregate energy usage on dense femtocell channels is formulated taking into account the cost of both the spectrum and energy usage. We investigate an energy-and-spectral efficient approach to balance between the two costs by varying the number of active sub-channels and their energy. The proposed scheme is addressed by deriving closed-form expressions for the interference towards the macrocell and the outage capacity. Analytically, discrete regions under which the most promising outage capacity is achieved by the same size of active sub-channels are introduced. Through a joint optimization of the sub-channels and their energy, properties can be found for the maximum outage capacity under realistic constraints. Using asymptotic and numerical analysis, it can be noticed that in a dense femtocell deployment, the optimum utilization of the energy and the spectrum to maximize the outage capacity converges towards a round-robin scheduling approach for a very small outage threshold. This is the inverse of the traditional greedy approach. © 2012 IEEE.
Arshad K, Moessner K (2009) Collaborative spectrum sensing: Optimising the number of collaborating users, Proceedings - 2009 1st UK-India International Workshop on Cognitive Wireless Systems, UKIWCWS 2009
In the IEEE 802.22 standard, the spectrum sensing mechanism is identified as a key functionality of a cognitive radio. Due to the channel uncertainty, a single cognitive user, in most cases, can not make a reliable decision and hence collaboration or cooperation of and among multiple users is required. However, when large number of cognitive users are collaborating with each other, the bandwidth requirements for sending their result to the fusion centre tends to be very large. In this paper, a metric for spectrum efficiency is defined and used for the optimisation of collaborative spectrum sensing. An optimisation algorithm is presented to calculate the optimal number of collaborating cognitive users with the aim to maximise overall spectrum efficiency by satisfying certain constraints in terms of global probability of detection and probability of false alarm. Numerical results show that for maximum spectrum efficiency collaboration of only a subset of the available cognitive users is required. © 2009 IEEE.
Wang W, De S, Cassar G, Moessner K (2015) An Experimental Study on Geospatial Indexing for Sensor Service Discovery, Expert Systems with Applications 42 (7) pp. 3528-3538 Elsevier
The Internet of Things enables human beings to better interact with and understand their surrounding environments by extending computational capabilities to the physical world. A critical driving force behind this is the rapid development and wide deployment of wireless sensor networks, which continuously produce a large amount of real-world data for many application domains. Similar to many other large-scale distributed technologies, interoperability and scalability are the prominent and persistent challenges. The proposal of sensor-as-a-service aims to address these challenges; however, to our knowledge, there are no concrete implementations of techniques to support the idea, in particular, large-scale, distributed sensor service discovery. Based on the distinctive characteristics of the sensor services, we develop a scalable discovery architecture using geospatial indexing techniques and semantic service technologies. We perform extensive experimental studies to verify the performance of the proposed method and its applicability to large-scale, distributed sensor service discovery.
In this paper interference management in co-channel deployment of macrocell and cognitive femtocells is investigated.
For the purpose of the aggregate interference mitigation from all femtocell access points (FAP) to macrocell user equipment (MUE) and the purpose to increase the radio link quality of
femtocell system, a parameter named interference tolerable threshold (Ith) is introduced, the aim is to reduce the interference an individual FAP causes to MUE to a level lower than Ith. A dynamic Ith control scheme is proposed to determine the appropriate value of this threshold. The simulation results show that the highest available Ith depends on the total number of FAPs, a larger number of FAPs does affect aggregate interference even if the individual interference is in acceptable
range. The proposed method, however, achieves the adaptation of the highest available Ith without needing knowledge about the number of FAPs in the vicinity of MUEs.
Xiao P, Tafazolli R, Moessner K, Gluhak A (2012) Codebook Based Single-User MIMO System Design with Widely Linear Processing, IEEE Transactions on Communications
This work addresses joint transceiver optimization for multiple-input, multiple-output (MIMO) systems. In practical systems the complete knowledge of channel state information (CSI) is hardly available at transmitter. To tackle this problem, we resort to the codebook approach to precoding design, where the receiver selects a precoding matrix from a finite set of pre-defined precoding matrices based on the instantaneous channel condition and delivers the index of the chosen precoding matrix to the transmitter via a bandwidth-constraint feedback channel. We show that, when the symbol constellation is improper, the joint codebook based precoding and equalization can be designed accordingly to achieve improved performance compared to the conventional system.
Ganz F, Barnaghi P, Carrez F, Moessner K (2011) Context-aware management for sensor networks, Proceedings of the 5th International Conference on Communication System Software and Middleware pp. 6:1-6:6 ACM
The wide field of wireless sensor networks requires that hun-
dreds or even thousands of sensor nodes have to be main-
tained and configured. With the upcoming initatives such
as Smart Home and Internet of Things, we need new mecha-
nism to discover and manage this amount of sensors. In this
paper, we describe a middleware architecture that uses con-
text information of sensors to supply a plug-and-play gate-
way and resource management framework for heterogeneous
sensor networks. Our main goals are to minimise the effort
for network engineers to configure and maintain the network
and supply a unified interface to access the underlying het-
erogeneous network. Based on the context information such
as battery status, routing information, location and radio
signal strength the gateway will configure and maintain the
sensor network. The sensors are associated to nearby base
stations using an approach that is adapted from the 802.11
WLAN association and negotiation mechanism to provide
registration and connectivity services for the underlying sen-
sor devices. This abstracted connection layer can be used to
integrate the underlying sensor networks into high-level ser-
vices and applications such as IP-based networks and Web
services.
Durowoju O, Arshad K, Moessner K (2013) Distributed power control and user selection algorithms for cognitive radios, IEEE Vehicular Technology Conference
The interference problem to Incumbent Users (IUs) of spectrum is herein addressed so as to prevent obtrusive cognitive transmissions at IU contours. In this paper, we present autonomous distributed power control algorithms for cognitive radios (CRs) in a Rayleigh fading environment with guarantees on IU protection whilst concurrently supporting an increased number of cognitive users. We further consider the user selection problem to maximise system capacity. Based on analysis and simulations we propose an efficient outage based distributed user removal algorithm that alleviates the interference environment for IUs and CRs alike with a substantial increase in number of supported CRs. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.
Barnaghi P, Cassar G, Moessner K (2010) Probabilistic Methods for Service Clustering, CEUR Workshop Proceedings: Proceedings of 4th International Workshop on Service Matchmaking and Resource Retrieval in the Semantic Web 667
This paper focuses on service clustering and uses service descriptions
to construct probabilistic models for service clustering.We discuss
how service descriptions can be enriched with machine-interpretable
semantics and then we investigate how these service descriptions can be
grouped in clusters in order to make discovery, ranking, and recommendation
faster and more effective. We propose using Probabilistic Latent
Semantic Analysis (PLSA) and Latent Dirichlet Allocation (LDA) (i.e.
two machine learning techniques used in Information Retrieval) to learn
latent factors from the corpus of service descriptions and group services
according to their latent factors. By creating an intermediate layer of
latent factors between the services and their descriptions, the dimensionality
of the model is reduced and services can be searched and linked
together based on probabilistic methods in latent space. The model can
cluster any newly added service with a direct calculation without requiring
to re-calculate the latent variables or re-train the model.
Guo T, Moessner K (2012) Optimal strategy for QoS provision under spectrum mobility in cognitive radio networks, IEEE Vehicular Technology Conference pp. 1-5 IEEE
In cognitive radio networks, the arrival of Primary Users (PUs) may force Secondary Users (SUs) to terminate their ongoing sessions or degrade their Quality of Service (QoS) level. Given the time-varying spectrum availability, an immediate challenge arising is to support the QoS of SUs under spectrum mobility. In this paper, we propose an optimal decision-making framework for joint admission control, eviction control and bandwidth adaptation in cognitive radio networks. The problem is formulated as a Semi-Markov Decision Process (SMDP) and the optimal decision for each system state is derived to maximize the long-term network revenue as a function of the spectrum utilization, the SU blocking probability and the bandwidth adaptation cost under the SU dropping probability constraint. It is shown that the derived optimal strategy outperforms the threshold-based channel reservation schemes with/without bandwidth adaptation. And among the schemes with bandwidth adaptation, more performance improvement can be achieved by the proposed one when the bandwidth adaptation cost is taken into account. © 2012 IEEE.
Li N, Tarus H, Irvine JM, Moessner K (2010) A communication middleware for ubiquitous multimedia adaptation services, Computing and Informatics 29 (4) pp. 629-646
Ubiquitous services have gained increasing attention in the area of mobile communication aiming to allow service access anywhere, anytime and anyhow while keeping complexity to a minimum for both users and service providers. Ubiquitous environment features a wide range and an increasing number of access devices and network technologies. Context-aware content/service adaptation is deemed necessary to ensure best user experience. We developed an Adaptation Management Framework (AMF) Web Service which manages the complexity of dynamic and autonomous content adaptation and serves as an invisible enabler for ubiquitous service delivery. It remains challenging to manage the tasks involved in the communication between the AMF Web Service and the user's environment, typically represented by various types of intelligent agents. This work presents a middleware which manages those tasks and serves not only as a protocol gateway, but also as a message translator, a service broker, a complexity shield etc., between AMF Web Services and User Agents.
Zhang R, Wang L, Parr G, Aliu OG, Awoseyila B, Azarmi N, Bhatti S, Bigham J, Bodanese E, Chen H, Dianati M, Dutta A, Fitch M, Giridhar K, Hailes S, Hari KVS, Imran MA, Jagannatham AK, Karandikar A, Kawade S, Khan MZA, Kompalli SC, Langdon P, Narayanan B, Mauthe A, McGeehan J, Mehta N, Millet K, Moessner K, Rajashekar R, Ramkumar B, Ribeiro V, Vasudevan K, Hanzo L (2013) Advances in Base- and Mobile-Station Aided Cooperative Wireless Communications, IEEE VEHICULAR TECHNOLOGY MAGAZINE 8 (1) pp. 57-69 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Muck M, Bourse D, Moessner K, Alonistioti N, Demestichas P, Nicollet E, Buracchini E, Bateman D, Boufidis Z, Patouni E, Stavroulaki V, Trogolo A, Goria P (2007) End-to-end reconfigurability in heterogeneous wireless systems - Software and cognitive radio solutions enriched by policy- and context-based decision making, 2007 16th IST Mobile and Wireless Communications Summit
This paper describes the End-to-End Reconfigurability (E2R IT) research framework and focuses on the current status of the activities inside the consortium. E2R II is a partly funded project inside the Sixth Framework Programme of European Community. The E2R II project is part of a wider program, started with the E2R I project in 2004. Tn this program, concepts and solutions in order to enable, manage and control the end-to-end connectivity in highly heterogeneous environments are developed, taking into account the different Radio Access Technologies potentially aclive (2G/3G cellular, 4G/B3G, IEEE 802.xx. broadcast...). The key objective of the E2R II project is to devise, develop, trial and showcase architectural design of reconfigurable devices and supporting system functions with the aim to offer an extensile set of operational choices to the users, application and service providers, operators, manufacturers and regulators in the context of heterogeneous systems.
Cassar G, Barnaghi P, Moessner K (2011) A probabilistic latent factor approach to service ranking, Proceedings - 2011 IEEE 7th International Conference on Intelligent Computer Communication and Processing, ICCP 2011 pp. 103-109
In this paper we investigate the use of probabilistic machine-learning techniques to extract latent factors from semantically enriched service descriptions. The latent factors provide a model to represent service descriptions of any type in vector form. With this conversion, heterogeneous service descriptions can be represented on the same homogeneous plane thus achieving interoperability between different service description technologies. Automated service discovery and ranking is achieved by extracting latent factors from queries and representing the queries in vector form. Vector algebra can then be used to match services to the query. This approach is scalable to large service repositories and provides an efficient mechanism for publishing new services after the system is deployed. © 2011 IEEE.
Jin Y, Vural S, Gluhak A, Moessner K (2013) Dynamic task allocation in multi-hop multimedia wireless sensor networks with low mobility., Sensors (Basel, Switzerland) 13 (10) pp. 13998-14028
This paper presents a task allocation-oriented framework to enable efficient in-network processing and cost-effective multi-hop resource sharing for dynamic multi-hop multimedia wireless sensor networks with low node mobility, e.g., pedestrian speeds. The proposed system incorporates a fast task reallocation algorithm to quickly recover from possible network service disruptions, such as node or link failures. An evolutional self-learning mechanism based on a genetic algorithm continuously adapts the system parameters in order to meet the desired application delay requirements, while also achieving a sufficiently long network lifetime. Since the algorithm runtime incurs considerable time delay while updating task assignments, we introduce an adaptive window size to limit the delay periods and ensure an up-to-date solution based on node mobility patterns and device processing capabilities. To the best of our knowledge, this is the first study that yields multi-objective task allocation in a mobile multi-hop wireless environment under dynamic conditions. Simulations are performed in various settings, and the results show considerable performance improvement in extending network lifetime compared to heuristic mechanisms. Furthermore, the proposed framework provides noticeable reduction in the frequency of missing application deadlines.
Moessner K, Vahid S, Tafazolli R (2001) Terminal reconfigureability-the OPTiMA framework, Proc. Second Int 3G Mobile Communication Technologies Conf. (Conf. Publ. No. 477) pp. 241-246
Gultchev S, Mitchell C, Moessner K, Tafazolli R (2002) Securing reconfigurable terminals - mechanisms and protocols, Proc. 13th IEEE Int Personal, Indoor and Mobile Radio Communications Symp 2 pp. 804-808
De S, Christophe B, Moessner K (2014) Semantic Enablers for Dynamic Digital-Physical Object Associations in a Federated Node Architecture for the Internet of Things, Ad Hoc Networks Journal 18 pp. 102-120 Elsevier
The Internet of Things (IoT) paradigm aims to realize heterogeneous physical world objects interacting with each other and with the surrounding environment. In this prospect, the automatic provisioning of the varied possible interactions and bridging them with the digital world is a key pertinent issue for enabling novel IoT applications. The introduction of description logic-based semantics to provide homogeneous descriptions of object capabilities enables lowering the heterogeneity and a limited set of interactions (such as those with stationary objects with fixed availability) to be deduced using classical reasoning systems. However, the inability of such semantics to capture the dynamics of an IoT system as well as the scalability issues that reasoning systems encounter if too many descriptions have to be processed, necessitate that such approaches should be used in conjunction with others. Towards this aim, this paper proposes an automated rule-based association mechanism for integrating the digital IoT components with physical entities along temporal-spatial-thematic axes. To address the scalability issue, this mechanism is distributed over a federated network of nodes, each embodying a set of objects located in the same geographical area. Nodes covering nearby geographical areas can share their object descriptions while all nodes are capable of deducing interactions between the descriptions that they are aware of.
Reetz ES, Kuemper D, Moessner K, Tönjes R (2014) Investigation of opportunities for test case selection optimisation based on similarity computation and search-based minimisation algorithms, VALID 2014 - 6th International Conference on Advances in System Testing and Validation Lifecycle pp. 14-20
Test Case Diversity investigations promise to reduce the number of Test Cases to be executed whereby addressing one of the drawbacks of automated model-based testing. Based on the assumption that more diverse Test Cases have a higher probability to fail, algorithms for distance analysis and search based minimisation techniques can help to enhance the quality of selection. This work discusses the application of Hamming Distance and Levenshtein Distance to compute similarity scores and outlines how Random Search and Hill Climbing can be applied to the problem of group optimisation based on pairwise Test Case similarity scores. The evaluation results, conducted with a test framework for automated test derivation and execution for IoT-based services, indicates that proposed Group Hill Climbing algorithm can outperform Random Search and at the same time utilising less computation time. The inclusion of the sequencebased Levenshtein algorithm shows advantages over the utilisation of the set-based Hamming-inspired scoring methodology.
Zhou D, Migault D, Wang Y, Akhtar N, Moessner K (2007) Map of Relaying Messages (MORM) an approach of message distribution enabling network advertisement and discovery, 2007 6th International Workshop on Design and Reliable Communication Networks, DRCN 2007
Next generation networks will be more and more heterogeneous and dynamic. The traditional model for interactions between different networks is relatively static. However, future scenarios involve quite dynamic inter-network relationships established to meet service requirements on-the-fly. In particular, Network Composition will enable dynamic and automatic cooperation between networks, based on agreements tailored to meet the specific needs of the networks concerned. To facilitate such interactions, functionality to advertise and to discover various networks and services within the local and remote scope will be required. In this paper, we address the twinfunctions of Network Advertisement and Discovery. A scenariobased analysis is used to determine the key requirements of these functions, with special emphasis on the problem of distributing advertisement and discovery messages to a set of unknown target networks. A novel solution called Map of Relaying Messages is presented to enable the efficient and timely distribution of various messages for the purpose of advertisement and discovery.
Arshad K, Moessner K (2009) Collaborative Spectrum Sensing for Cognitive Radio, 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATION WORKSHOPS, VOLS 1 AND 2 pp. 371-375 IEEE
Liu X, Evans BG, Moessner K (2013) Comparison of reliability, delay and complexity for standalone cognitive radio spectrum sensing schemes, IET Communications 7 (9) pp. 799-807
The ability to reliably and autonomously identify unused frequency bands plays an extremely important role in cognitive radio networks. Relying on the spectrum sensing, ongoing licensed operation must not be compromised and the secondary spectrum usage efficiency should be maintained. Thus, it is critical to ensure that the confidence level of the estimated signal status satisfies the primary user's requirement, while keeping the delay and computational complexity to a minimum. This study provides a comprehensive comparison in terms of performance, reliability and complexity of standalone sensing schemes for various cognitive radio application areas. The authors first give some new results on reliability performance, and then evaluate the sensing time required to achieve the target performance. Finally, the authors compare the computational complexity of various sensing approaches by calculating the number of arithmetic operations required by each approach. © The Institution of Engineering and Technology 2013.
AlShahwan F, Moessner K, Carrez F (2011) Distributing resource intensive mobile web services, 2011 International Conference on Innovations in Information Technology, IIT 2011 pp. 41-46
One of the goals that can be achieved by providing adaptive web services from mobile hosts is to allow continuous service provisioning. However, there are limitations in terms of complexity and size of the services that may be executed on mobile hosts. In this paper, two steps are taken towards providing adaptive web services from resource limited mobile devices. The first step is to investigate mechanisms that facilitate distributing the execution of mobile web services; the main mechanisms are offloading and migration. The second step is to integrate these mechanisms with available web service architectures to produce an extended mobile web service framework. In this case we integrated them with both SOAP as well as REST. The paper describes the offloading and migration mechanisms as well as the implementation of a prototype that allows performance evaluation of both extended frameworks. To investigate the load and performance of the distributed services, the prototype implements resource intensive applications. The results presented show that basing distributed mobile-hosted services on REST is more suitable than using SOAP as underlying web service infrastructure. © 2011 IEEE.
Zahir T, Arshad K, Ko Y, Moessner K (2011) A downlink power control scheme for interference avoidance in femtocells, IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference pp. 1222-1226
Femtocells being small low powered base stations provide sufficient increase in system capacity along with better indoor coverage. However, the dense deployment of femtocells face the main challenge of co channel interference with macrocell users. In this paper, this interference problem is addressed by proposing a novel downlink power control algorithm for femtocells. The proposed algorithm gradually reduces the downlink transmit power of femtocells when they are informed about a nearby macrocell user under interference. This information is given to the femtocells by the macrocell base station through a unidirectional downlink broadcast channel. Simulation results show that the algorithm causes the macrocell to accommodate large number of femtocells within its area, whereas at the same time protecting the macrocell users from any harmful interference. © 2011 IEEE.
Gultchev S, Moessner K, Tafazolli R, Anders J (2004) Reconfigurable software based communication - video services in reconfigurable mobile devices, Proc. Fifth IEE Int. Conf. 3G Mobile Communication Technologies 3G 2004 pp. 422-426
Zhang Q, Moessner K (2012) A context aware architecture for energy efficient cognitive radio, 77 LNICST pp. 452-462
Energy efficiency is a critical issue for future wireless communication. The European FP7 C2POWER project is to research, develop and demonstrate energy saving technologies for multi-standard wireless mobile devices, exploiting the combination of Cognitive Radio and cooperative strategies. The basic objective is to establish an energy optimization framework founded upon energy aware Cognitive Radio nodes which can dynamically optimize energy consumption while satisfying desired Quality of Service (QoS) for specific radio environments and applications. The context awareness for energy efficient Cognitive Radio can be seen as decision-making processes to optimize energy saving strategy based on energy related context information. The decision of a single node may have impacts on the energy consumption of other nodes and the entire Cognitive Radio network. Such decision-making processes are interactive. Game theory provides a mathematical basis for the analysis of interactive decision making processes. This paper presents a context aware architecture for energy efficient Cognitive Radio network from a game theoretical perspective. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.
Ayyadurai V, Moessner K, Tafazolli R (2012) Multipath network coding in wireless mesh networks, pp. 267-274
A practical wireless network solution for providing community broadband Internet access services are considered to be wireless mesh networks with delay-throughput tradeoff. This important aspect of network design lies in the capability to simultaneously support multiple independent mesh connections at the intermediate mobile stations. The intermediate mobile stations act as routers by combining network packets with forwarding, a scenario usually known as multiple coding unicasts. The problem of efficient network design for such applications based on multipath network coding with delay control on packet servicing is considered. The simulated solution involves a joint consideration of wireless media access control (MAC) and network-layer multipath selection. Rather than considering general wireless mesh networks, here the focus is on a relatively small-scale mesh network with multiple sources and multiple sinks suitable for multihop wireless backhaul applications within WiMAX standard. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.
Pérez-Romero J, Sallent O, Bouali F, Sarvanko H, Mustonen M, Matinmikko M, Lee H, Vahid S, Moessner K (2012) A spectrum selection framework for Opportunistic Networks, 2012 Future Network and Mobile Summit, FutureNetw 2012
This paper presents a framework for including cognitive management functionalities in the spectrum selection process for Opportunistic Networks (ONs).The framework is based on a decision making functionality interacting with a knowledge management block that stores and processes information about the spectrum use. Different approaches for spectrum selection are discussed covering specific cases including the capability to aggregate different bands and the possibility to jointly select the spectrum and the network interface. Illustrative results of the proposed framework are presented. © 2012 IIMC Ltd.
Gultchev S, Moessner K, Tafazolli R (2002) Controlling reconfiguration, Proc. Third Int 3G Mobile Communication Technologies Conf. (Conf. Publ. No. 489) pp. 474-478
Triantafyllopoulou D, Guo T, Moessner K (2012) Energy Efficient ANDSF-assisted Network Discovery for non-3GPP Access Networks, pp. 297-301 IEEE
The aim of this paper is to improve the energy efficiency during network discovery in heterogeneous networking environments. To this end, we propose a novel network discovery algorithm that exploits both user and network context information in order to efficiently adapt the network scanning period, thus avoiding unnecessary energy-consuming scanning or mis-detection of available networks that can be used as targets of handover. The performance of the proposed algorithm is compared against a system that performs network scanning in a periodic manner, without taking into consideration the user and network context information. According to simulation results, the system that employs the proposed network discovery algorithm achieves significant performance improvement in terms of energy consumption and network detection delay, with no loss in the network detection rate.
Akbar A, Carrez F, Moessner K, Sancho J, Rico J (2015) Context-Aware Stream Processing for Distributed IoT Applications, 2015 IEEE 2ND WORLD FORUM ON INTERNET OF THINGS (WF-IOT) pp. 663-668 IEEE
Yu X, Navaratnam P, Moessner K (2012) Performance analysis of distributed resource reservation in IEEE 802.11e-based wireless networks, IET Communications 6 (11) pp. 1447-1455
Guaranteeing quality of service (QoS) is one of the most critical challenges in IEEE 802.11-based wireless networks. This study proposes an analytical framework to evaluate hybrid medium access control (MAC) scheduling mechanisms with distributed resource reservation (RR), that was proposed for the IEEE 802.11e-enhanced distributed channel access protocol for guaranteeing QoS. The hybrid MAC scheduling mechanisms split the airtime into service intervals with contention-free period for QoS guaranteed real-time sessions (RTSNs), and contention access period for other traffic sessions. The distributed RR ensures that the resources are allocated to RTSNs without the support of a centralised controller-this makes it suitable for ad hoc networking applications. The proposed analytical framework models the QoS (i.e. delay and throughput) performance of RTSNs with dedicated resources in a distributed environment, and also estimates the overall capacity of the network. Moreover, the derived models can be used to investigate the impact of changes to individual system parameters, such as service interval or size of transmission opportunity. The simulation results show that the proposed analytical framework precisely models the QoS performance of RTSNs and predicts the optimum resource allocation for improved network capacity. © 2012 The Institution of Engineering and Technology.
Moessner K, Vahid S, Tafazolli R (1999) Extension of the PNNI to support mobility management and handoffs in WATM networks based on CORBA, Proc. IEEE 49th Vehicular Technology Conf 3 pp. 2515-2519
Jin Y, Wei D, Gluhak A, Moessner K (2010) Latency and energy-consumption optimized task allocation in wireless sensor networks, IEEE Wireless Communications and Networking Conference, WCNC
Emerging applications in Wireless Sensor Networks (WSNs) demand notable in-network processing capacities rather than simple data gathering and dissemination. Therefore, the performances of the network like latency and energy consumption are greatly affected by how the various application requirements are mapped to the processing nodes in the network. This paper investigates intelligent task mapping and scheduling techniques based on Genetic Algorithm (GA), and proposes a novel task allocation model and a multi-hop communication model to schedule both computation and communication activities in the WSN environment. A hybrid fitness function which balances the energy consumption among collaborative sensor nodes with application tolerable delays is presented to extend the network lifetime. Simulation results show that the proposed algorithm has a better capability of balancing the network lifetime with latency constraints in both homogeneous and heterogeneous networks. ©2010 IEEE.
Fan L, Akhtar N, Chew KA, Moessner K, Tafazolli R (2004) Network composition: a step towards pervasive computing, Proc. Fifth IEE Int. Conf. 3G Mobile Communication Technologies 3G 2004 pp. 198-202
Itaya S, Kanhere S, Aust S, Alfandi O, Altintas O, Bochow B, Bohli JM, Boyle D, Chakraborty D, Chou CT, Davis P, Doi SI, Emmelmann M, Heemstra De Groot S, Iwaoka M, Konishi T, Krishnaswamy D, Marusic S, Moessner K, Mogre P, Prasad V, Rao VS, Saha D, Schülke A, Shinkuma R, Takai M, Yan Z, Dong AY, Headley W (2013) Welcome message from the IEEE goSMART chairs, Proceedings - Conference on Local Computer Networks, LCN
Poncela J, Vlacheas P, Giaffreda R, De S, Vecchio M, Nechifor S, Barco R, Aguayo-Torres MC, Stavroulaki V, Moessner K, Demestichas P (2014) Smart Cities via Data Aggregation, Wireless Personal Communications 76 (2) pp. 149-168 Springer
Cities have an ever increasing wealth of sensing capabilities, recently including also internet of things (IoT) systems. However, to fully exploit such sensing capabilities with the aim of offering effective city-sensing-driven applications still presents certain obstacles. Indeed, at present, the main limitation in this respect consists of the vast majority of data sources being served on a ?best effort? basis. To overcome this limitation, we propose a ?resilient and adaptive IoT and social sensing platform?. Resilience guarantees the accurate, timely and dependable delivery of the complete/related data required by smart-city applications, while adaptability is introduced to ensure optimal handling of the changing requirements during application provision. The associated middleware consists of two main sets of functionalities: (a) formulation of sensing requests: selection and discovery of the appropriate data sources; and (b) establishment and control of the necessary resources (e.g., smart objects, networks, computing/storage points) on the delivery path from sensing devices to the requesting applications. The middleware has the intrinsic feature of producing sensing information at a certain level of detail (geographical scope/timeliness/accuracy/completeness/dependability) as requested by the applications in a given domain. The middleware is assessed and validated at a proof-of-concept level through innovative, dependable and real-time applications expected to be highly reproducible across different cities.
Triantafyllopoulou D, Moessner K, Kliks A, Bogucka H, Zalonis A, Dagres I, Dimitriou N, Polydoros A (2013) A Context-Aware Decision Making Framework for Cognitive and Coexisting Networking Environments, 19th European Wireless Conference VDE Verlag
One of the major challenges in cognitive and cooperative communication systems that support advanced coexistence technologies for radio resource usage optimization is efficient decision making. However, the high dynamicity of such communication environments, in conjunction with the existence of an increasing amount of diverse context information, result in decision making becoming a non-trivial issue. In this paper, we present a novel decision making framework for modern wireless communication environments. More specifically, the different steps of the decision making cycle and the role they play in the decision making process are presented, while the different fragments that constitute the notion of context, as well as their role and the way they interact with and influence the decision making steps are described in detail. Moreover, two case-studies, on interference management in heterogeneous networks and noise-robust and energy-efficient sensing, respectively, are presented, highlighting their compliance with the described decision making framework.
Alshahwan F, Moessner K, Carrez F (2011) Distribute provision strategies of RESTful-based mobile web services, IEEE Global Telecommunications Conference 2011 IEEE
Providing adaptive web services from mobile hosts is a new approach in mobile web services to cope resource scarcity of mobile network environment. This approach is explored through investigating some mechanisms to allow continuous and reliable service provisioning. However, there is a clear limitation in terms complexity and size of the services that may be executed on mobile hosts. In this paper, Simple Partial Offloading mechanism is studied to facilitate mobile web service adaptation through distributing the execution of mobile web services and modeling the transfer of required location-based information. The distribution can be classified into Forward or Bounce offloading while the transfer modeling is based on either Frontend or Backend scheme. Hence, four distinct types of mobile web service frameworks have been implemented; each of these architectures represents a different strategy for achieving adaptive and distributed web services. The paper describes the four prototypes that allow performance evaluation using resource intensive applications. The results presented show that basing distributed mobile hosted services on Backend Bounce Offload strategy is more suitable for mobile network environment.
Lee H, Vahid S, Moessner K (2012) Utility-based dynamic spectrum aggregation algorithm in cognitive radio networks, IEEE Vehicular Technology Conference
In this paper, we propose a utility-based spectrum aggregation algorithm to enhance the performance of a cognitive radio network considering multiple objectives: (i) maximization of overall throughput, (ii) reduction of channel switching, (iii) reducing the number of sub-channels comprising the aggregate channel, aimed at opportunistic spectrum use by secondary users (SUs). These three objectives are integrated into a weighted sum utility function. The weight associated with each objective can be set differently (typically done manually) depending on the metric to be optimized. In this article however, we propose and evaluate an automatic mechanism for setting weights. The proposed algorithm including the learning module allows for automated (no manual intervention) adaptable setting of objective- function weights depending on the environment changes and its performance is also shown via the simulation results. © 2012 IEEE.
Dimitrakopoulos G, Moessner K, Kloeck C, Grandblaise D, Gault S, Sallent O, Tsagkaris K, Demestichas P (2006) Adaptive resource management platform for reconfigurable networks, MOBILE NETWORKS & APPLICATIONS 11 (6) pp. 799-811 SPRINGER
De S, Attou A, Moessner K (2009) Service and Content Presentation in Ubiquitous Environments, pp. 61-64 Springer
The heterogeneous, dynamic nature of ubiquitous environments necessitates that all system components that form part of a personalisation framework should be context aware. Personalised service delivery requires that the system must detect and interpret device modality contexts in real time and provide automated adaptation on behalf of the user. Towards this aim, this paper presents the design and implementation of a demonstrator that offers personalised, context sensitive, service and content delivery.
Yu X, Navaratnam P, Moessner K (2011) Distributed resource reservation for real time sessions in multi-hop wireless networks, IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference pp. 255-260
Quality of Service (QoS) provisioning in multi-hop wireless networks (MHWNs) has become a promising and challenging topic in the wireless communication research community. In this paper, a novel distributed MAC scheduling protocol with reservation mechanism is proposed for enhancing the QoS performance of IEEE 802.11e-based MHWNs. The proposed mechanism guarantees resources in pre-configured contention-free period (CFP) for real-time sessions (RTSNs) in the network in a distributed manner. Here, resource reservation (RR) for multiple sessions can be made without any collision through an effective signalling process which coordinates the RR for RTSNs. Distributed admission control (AC) ensures that the existing RTSNs are not violated from QoS guarantees. In addition, a concurrent transmission (CT) mechanism is implemented within the pre-configured CFP. This is to further improve the bandwidth utilization by synchronizing the reserved transmissions among different nodes which do not interfere with each other. Simulation results indicate that the proposed scheduling mechanism can address the problems posed by inter- and intra-flow interference and can achieve guaranteed QoS for admitted RTSNs while providing fairness for the other sessions in the network. © 2011 IEEE.
Attou A, Li N, Moessner K (2008) Context for multimedia services adaptation, MOBIMEDIA 2008 - 4th International ICST Mobile Multimedia Communications Conference
Due to the heterogeneity and complexity of user environments, multimedia services and multimedia content in the communication domain, adaptation is of a paramount importance to interoperability. Adaptation decisions at the different stages of multimedia services delivery to the end user depends on contextual information, i.e. metadata that characterises the situation of entities involved in the interaction between the user and multimedia services. This paper presents how the Adaptation Manager processes and models contextual information, and how it complements the decision taking framework defined by MPEG-21 DIA. The use of important standards and technologies such as MPEG-21 DIA, XML, Description Logics and OWL is explained. Copyright 2008 ICST.
Rodriguez V, Moessner K, Tafazolli R (2006) Market driven dynamic spectrum allocation over space and time among radio-access networks: DVB-T and B3G CDMA with heterogeneous terminals, MOBILE NETWORKS & APPLICATIONS 11 (6) pp. 847-860 SPRINGER
Lee H, Vahid S, Moessner K (2013) A survey of radio resource management for spectrum aggregation in LTE-advanced, IEEE Communications Surveys and Tutorials 16 (2) pp. 745-760
In order to satisfy the requirements of future IMT-Advanced mobile systems, the concept of spectrum aggregation is introduced by 3GPP in its new LTE-Advanced (LTE Rel. 10) standards. While spectrum aggregation allows aggregation of carrier components (CCs) dispersed within and across different bands (intra/inter-band) as well as combination of CCs having different bandwidths, spectrum aggregation is expected to provide a powerful boost to the user throughput in LTE-Advanced (LTE-A). However, introduction of spectrum aggregation or carrier aggregation (CA) as referred to in LTE Rel. 10, has required some changes from the baseline LTE Rel. 8 although each CC in LTE-A remains backward compatible with LTE Rel. 8. This article provides a review of spectrum aggregation techniques, followed by requirements on radio resource management (RRM) functionality in support of CA. On-going research on the different RRM aspects and algorithms to support CA in LTE-Advanced are surveyed. Technical challenges for future research on aggregation in LTE-Advanced systems are also outlined. © 2014 IEEE.
Yu X, Navaratnam P, Moessner K (2013) Resource reservation schemes for IEEE 802.11-based wireless networks: A survey, IEEE Communications Surveys and Tutorials 15 (3) pp. 1042-1061
IEEE 802.11-based wireless technology is widely applied in many areas, supporting communications where wired devices are not available. However, providing satisfactory QoS is still a challenging topic in 802.11-based wireless networks because of the problems such as error-prone wireless channel condition, power consumption, short of centralised facility, mobility as well as channel contention. For addressing these issues, one feasible solution can be to implement resource reservation for the sessions that require QoS assurances. The responsibility of resource reservation scheme is to make sure that QoS-sensitive sessions get sufficient bandwidth in order to sustain their high performance. Difficulties are already identified for designing resource reservation schemes in both network and MAC layers. However, there is no profound investigation outcome for this kind of QoS mechanism. Therefore, in this paper, we intend to produce a comprehensive survey of resource reservation approaches for IEEE 802.11-based wireless networks. The associated research works are summarised and also classified. Moreover, both the drawbacks and the merits of each kind of resource reservation scheme are highlighted. © 2013 IEEE.
Prammanee S, Moessner K (2008) Mobile Multimodality: A Theoretical Approach to Facilitate Virtual Device Environments, MOBILE NETWORKS & APPLICATIONS 13 (6) pp. 569-582 SPRINGER
Pozza R, Nati M, Georgoulas S, Moessner K, Gluhak A (2015) Neighbor Discovery for Opportunistic Networking in Internet of Things Scenarios: A Survey, IEEE ACCESS 3 pp. 1101-1131 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Deschamps B, Moessner K, Smith B (2010) Regulation requirements of advanced spectrum exploitation technologies, 2010 Future Network and Mobile Summit
Even today many papers and presentations make the claim that there is sufficient spectrum available for all new and future services, if only the spectrum could be used more efficiently, inter alia through additional flexibility in the assignment of frequencies to those systems that need the spectrum at a certain point in time at a given location. It still seems common understanding that radio regulation and the rules applicable for the deployment of systems and use of radio spectrum resources are by far too rigid and regulators are supposed to be not sufficiently forward looking. The claim goes that regulation needs to be changed in a way that the rules will allow dynamic access and thus increase efficiency that is expected to be facilitated by the extreme flexibility provided by the new dynamic spectrum access, flexible spectrum and cognitive radio system technologies. However, this is, to a large extend a misconception, as regulation has evolved over the last decade, regulators have changed the way spectrum is licensed and the conditions under which it can be used. This paper provides an overview of the current spectrum regulatory landscape covering the developments, in particular in Europe, including the WAPECS and BEM approaches, the impact of E3 on regulation as well as considering the changes that came along globally. The paper also contains an argument on the real changes that are still required to permit the use of state-of-theart dynamic spectrum assignment or access technologies and approaches. Copyright © 2010 The authors.
Li N, Attou A, De S, Moessner K (2008) Device and service descriptions for ontology-based ubiquitous multimedia services, MoMM2008 - The 6th International Conference on Advances in Mobile Computing and Multimedia pp. 370-375
Multimedia services are becoming increasingly popular among mobile users. Ontology and related technologies have been introduced into the multimedia domain as a means to provide declarative formal representations of the domain knowledge and thus to enable intelligent multimedia processing, such as media format adaptation. The range of devices available to access media content becomes increasingly heterogeneous and at the same time ubiquitous. Users expect to access their services and content without restrictions in time or location. Users have many and different gadgets/devices with network connectivity at their disposal to receive content, ranging from their smart phones, car audio systems to laptops, or office PCs, etc. Hence there is a need to link the discovery and the description of these ambient device with multimedia domain knowledge representations in order to facilitate a ubiquitous multimedia experience. The contribution of this work is an approach for mapping device descriptions, which are leveraged on the resource discovery protocol UPnP to OWL ontology instances. The ontology instances chosen are compliant with the MPEG-21 DIA OWL-formatted ontology. This approach bridges the gap between non-semantic description mechanisms of the legacy device/services discovery protocol with the semantic multimedia domain knowledge representation. © 2008 ACM.
Triantafyllopoulou D, Moessner K, Alam M, Radwan A, Rodriguez J (2014) Cognitive Means Smart: Knowledge Saves Power, In: Radwan A, Rodriguez J (eds.), Energy Efficient Smart Phones for 5G Networks 6 Springer
The previous chapters mainly examined methods to save energy at the mobile handset, either by using short-range cooperation between mobile terminals, or by performing smart vertical handovers between heterogeneous radio access technologies. These techniques can be beneficial to mobile systems, but they have to be performed based on informed decisions; meaning that mobile devices need to be cognitive. Modern devices already collect significant amounts of information, but they have limited capability to exploit such context/information, and handover decisions are merely based on signal strength, or are network controlled and based on network load. In this chapter, we aim to go beyond the state-of-the-art by envisioning mobile terminals with the capability to make informed decisions based on a reservoir of context information made available through context providers; namely what is referred to as smart phones. We include a survey of the current state of the art for context extraction and management in context-aware systems; besides listing the current context extraction techniques and research efforts, we pinpoint the important properties of good context extraction techniques. Thereafter, we discuss how context information can be exploited in energy saving when performing network or node discovery mechanism, by instructing the mechanisms to scan for certain nodes/networks which are known to be in the vicinity. Finally, we discuss the range of context information that can be used to make informed decisions to save power.
Triantafyllopoulou D, Kollias K, Moessner K (2015) QoS and Energy Efficient Resource Allocation in Uplink SC-FDMA Systems, IEEE Transactions on Wireless Communications 14 (6)
In this paper we present and evaluate the performance of a resource allocation algorithm to enhance the Quality of Service (QoS) provision and energy efficiency of uplink Long Term Evolution (LTE) systems. The proposed algorithm considers the main constraints in uplink LTE resource allocation, i.e., the allocation of contiguous sets of resource blocks of the localized Single Carrier ? Frequency Division Multiple Access (SC-FDMA) physical layer to each user, and the imperfect knowledge of the users' uplink buffer status and packet waiting time. The optimal resource allocation is formulated as a discrete connected cake-cutting problem, where different agents are allocated consecutive subsequences of a sequence of indivisible items. This problem is NP-hard, therefore a suboptimal algorithm is introduced, which performs resource allocation using information on the estimated uplink packet delay, the average delay and data rate of past allocations, as well as the required uplink power per resource block. Based on simulation results, the proposed algorithm achieves significant performance improvement in terms of packet timeout rate, goodput, and fairness. Moreover, the effect of poor QoS provision on energy efficiency is demonstrated through the evaluation of the performance in terms of energy consumption per successfully received bit.
Jefferies N, Irvine J, Munro A, Moessner K (2001) Managing increasingly software dependent mobile systems, Proc. Second Int 3G Mobile Communication Technologies Conf. (Conf. Publ. No. 477) pp. 247-251
Yu X, Navaratnam P, Moessner K (2012) Resource reservation schemes for IEEE 802.11e based wireless networks, IEEE Communications Surveys and Tutorials
Grandblaise D, Moessner K, Vivier G, Tafazolli R (2006) Rental protocol for automated spectrum sharing negotiation between base stations, FREQUENZ 60 (9-10) pp. 162-166 FACHVERLAG SCHIELE SCHON
Arshad K, Moessner K (2011) Robust collaborative spectrum sensing based on beta reputation system, 2011 Future Network and Mobile Summit
Collaborative spectrum sensing has been widely accepted as a promising approach to improve spectrum sensing performance by exploiting spatial diversity of cognitive radio users. However, in the presence of malfunctioning or misbehaved users, performance of collaborative spectrum sensing deteriorates significantly. In this paper, a credibility based mechanism for collaborative spectrum sensing using beta reputation system has been introduced. Our proposed method works well even if the total number of misbehaved users is unknown. In the proposed scheme, fusion center assigns weight to each user observation based on individual user credibility score. User credibility score is calculated using beta reputation system and simulation results show that proposed scheme significantly improves the reliability of aggregated data in the presence of falsified users.
Lee H, Vahid S, Moessner K (2014) The study on spectrum/channel fragmentation from dynamic spectrum aggregation in CRNs, EuCNC 2014 - European Conference on Networks and Communications
We study the dynamic spectrum aggregation and allocation problem in cognitive radio networks (CRNs). When the available spectrum is fragmented and the bandwidth of the spectrum holes is narrow, spectrum aggregation can be a solution to use multiple holes. Since the spectrum holes can have different bandwidth and cognitive radios can dynamically adjust the centre frequency and the bandwidth for each transmission, the CRN has the high flexibility in spectrum use with aggregation. However, aggregation of fragmented spectrum can lead to channel fragmentation and further spectrum fragmentation. In this context, we formulate the dynamic spectrum aggregation problem considering practical hardware constraints whilst aiming to minimise spectrum/channel fragmentation. Then, we study the application of three well-known memory allocation techniques, to spectrum aggregation, and analyse the impacts of the spectrum aggregation on spectrum/channel fragmentation. Based on the analysis, we derive guidelines that govern the design of the efficient spectrum aggregation and allocation algorithms. © 2014 IEEE.
Yu X, Navaratnam P, Moessner K (2012) Distributed interference-aware admission control with soft resource allocation for hybrid MAC in wireless mesh networks, IEEE International Conference on Communications pp. 455-460
Supporting quality of service (QoS) while fulfilling high efficiency of bandwidth utilization is challenging in wireless mesh networks. To deal with this issue, hybrid medium access control (MAC) protocols are effective candidates because they can achieve QoS support and better resource sharing at the same time. However, in multi-hop communication environments, hybrid MAC protocols suffer from interference and low bandwidth efficiency. To solve these problems, in this paper, we propose a distributed interference-aware admission control algorithm (DIACA) with soft resource allocation for hybrid MAC protocols suitable for IEEE 802.11 wireless mesh networks; a scheme for providing QoS improvement for real-time sessions (RTSNs) while enhancing the efficiency of bandwidth utilization. The proposed DIACA possesses a function for interference probing, making each node recognize their interfering counterparts. Further, through support of interference detection, concurrent transmissions can be achieved by letting non-interfering nodes transmit data simultaneously along a route which improves the efficiency of spatial reuse of bandwidth. In addition, the DIACA can implement soft resource allocation for RTSNs having delay requirements but loose (or low) throughput demands. By using soft resource allocation, a transmission opportunity can be shared by different RTSNs with low data rates and each of the RTSNs can obtain satisfactory QoS. Simulation results indicate that the proposed admission control algorithm can significantly enhance the bandwidth utilization of wireless channel and can improve QoS for RTSNs. © 2012 IEEE.
Lee H, Ko Y, Vahid S, Moessner K (2014) Opportunistic spectrum aggregation for cognitive communications under collision constraints, Proceedings of the 2014 9th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2014 pp. 7-12
We consider a collision-sensitive secondary system that intends to opportunistically aggregate and utilize spectrum of a primary system to achieve higher data rates. In such opportunistic spectrum access, secondary transmission can collide with primary transmission. When the secondary system aggregates more channels for data transmission, more frequent collisions may occur, limiting the performance obtained by the opportunistic spectrum aggregation. In this context, dynamic spectrum aggregation problem is formulated to maximize the ergodic channel capacity under the constraint of collision tolerable level. To solve the problem, we develop the optimal spectrum aggregation approach, deriving closed-form expressions for the collision probability in terms of primary user traffic load, secondary user transmission interval, and the random number of sub-channels aggregated. Our results show that aggregating only a subset of sub-channels will be a better choice, depending on the ratio of collision sensitivity requirement to the primary user traffic. © 2014 ICST.
Georgoulas S, Moessner K, Mansour A, Pissarides M, Spapis P (2012) A fuzzy reinforcement learning approach for pre-congestion notification based admission control, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 7279 LNCS pp. 26-37
Admission control aims to compensate for the inability of slow-changing network configurations to react rapidly enough to load fluctuations. Even though many admission control approaches exist, most of them suffer from the fact that they are based on some very rigid assumptions about the per-flow and aggregate underlying traffic models, requiring manual reconfiguration of their parameters in a "trial and error" fashion when these original assumptions stop being valid. In this paper we present a fuzzy reinforcement learning admission control approach based on the increasingly popular Pre-Congestion Notification framework that requires no a priori knowledge about traffic flow characteristics, traffic models and flow dynamics. By means of simulations we show that the scheme can perform well under a variety of traffic and load conditions and adapt its behavior accordingly without requiring any overly complicated operations and with no need for manual and frequent reconfigurations. © 2012 IFIP International Federation for Information Processing.
Wei D, Jin Y, Gluhak A, Tafazolli R, Moessner K (2010) Hot-spot issue aware clustering for WSNs to extend stable operation period, 2010 Future Network and Mobile Summit
In existing energy-efficient clustering algorithms for Wireless Sensor Networks (WSNs), individual nodes usually experience significant differences in lifetime. The issue of some nodes depleting energy earlier than other is usually referred to as hot-spot issue in WSNs, which dramatically shortens the stable operation period of a network when all nodes are live with residual energy. This paper addresses hot-spot issue through equalizing individual node's lifetime throughout the network. The probability of nodes to become cluster-head (CH) in this algorithm is relevant to node distance to the sink and is subject to the individual node-lifetime equalization. When selecting CHs, the residual node energy is considered as well. Performance evaluation illustrates the effectiveness of our algorithm in terms of extending the stable operation period of the clustered WSNs. Copyright © 2010 The authors.
AlShahwan F, Carrez F, Moessner K (2012) Providing and evaluating the mobile Web service distribution mechanisms using fuzzy logic, Journal of Software 7 (7) pp. 1473-1487 Academy Publisher
providing adaptive resource intensive Web services from mobile hosts needs to be done in a rather light-weight manner to allow continuous service provisioning. Processing and communication will drain the battery rapidly; hence both should be kept at a minimum. This paper describes the outcomes of an investigation into offloading and migration mechanisms that facilitate provision of adaptive and distributed mobile Web services. The investigation goes through three phases. The first phase integrates these mechanisms with the Simple Object Access Protocol (SOAP) and Representational State Transfer (REST) architectures producing extended mobile Web service frameworks. This phase is achieved by the implementation of a prototype that allows performance evaluation of both extended frameworks. The evaluation of the load and performance of the distributed services is taking place using resource intensive applications. The results presented show that basing distributed mobilehosted services on REST is more suitable than using SOAP as underlying Web service infrastructure. The second phase relies on the outperforming REST-based framework to examine four distinct strategies for mobile Web service distribution mechanisms. In the last phase, evaluation results of the second phase are interpreted as Fuzzy Logic rules. These rule sets are used to trigger and control offloading schemes. © 2012 ACADEMY PUBLISHER.
Zahir T, Arshad K, Nakata A, Moessner K (2012) Interference Management in Femtocells, IEEE Communications Surveys and Tutorials 15 (1) pp. 293-311 IEEE
Increase in system capacity and data rates can be achieved efficiently in a wireless system by getting the transmitter and receiver closer to each other. Femtocells deployed in the macrocell significantly improve the indoor coverage and provide better user experience. The femtocell base station called as Femtocell Access Point (FAP) is fully user deployed and hence reduces the infrastructure, maintenance and operational cost of the operator while at the same time providing good Quality of Service (QoS) to the end user and high network capacity gains. However, the mass deployment of femtocell faces a number of challenges, among which interference management is of much importance, as the fundamental limits of capacity and achievable data rates mainly depends on the interference faced by the femtocell network. To cope with the technical challenges including interference management faced by the femtocells, researchers have suggested a variety of solutions. These solutions vary depending on the physical layer technology and the specific scenarios considered. Furthermore, the cognitive capabilities, as a functionality of femtocell have also been discussed in this survey. This article summarises the main concepts of femtocells that are covered in literature and the major challenges faced in its large scale deployment. The main challenge of interference management is discussed in detail with its types in femtocells and the solutions proposed over the years to manage interference have been summarised. In addition an overview of the current femtocell standardisation and the future research direction of femtocells have also been provided.
Durowoju O, Gronsund P, Moessner K (2013) Distributed power control for secondary spectrum trading with incumbent protection, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC pp. 56-60
Spectrum trading allows incumbents of spectrum to increase their profit margins by selling portions of unused spectrum to secondary systems. While being a spectrally efficient process; interference from secondary usage degrades the performance of the incumbent network. We propose distributed power control algorithms with incumbent protection for secondary systems which is incorporated in the incumbent's pricing mechanism. Pricing is a fundamental part of the spectrum trading economic model; it indicates the value of spectrum to both buyers (SSP) and sellers (PSP) and influences the forces of demand and supply. There exist a compromise between the accrued revenue from spectrum trading and the resultant QoS degradation caused by SSPs to PSPs. interference from SSPs may increase churn within the PSP network, therefore, pricing algorithms need to be efficiently designed to capture PSPs profit in relation to the magnitude of SSPs interference. We consider distributed power control algorithms (PCA) for the SSP network and allow secondary spectrum trading in TV white spaces (TVWS) and demonstrate that a PSP can profit from secondary spectrum trading without obtrusive interference from SSPs. The power control algorithm introduced therefore ensures that the incumbent's interference threshold is never violated, leading to increased profit and reduced churn for the incumbent operator and improved quality of service for the secondary system due to spectrum buy. © 2013 IEEE.
Yu X, Navaratnam P, Moessner K (2012) Distributed MAC scheduling mechanism based on resource reservation for IEEE 802.11e-based multi-hop wireless networks, IEEE Wireless Communications and Networking Conference, WCNC pp. 1782-1787
Multi-hop wireless communication is playing a key role in today's communication networks. Despite several advancements in communication protocols and technologies, QoS provisioning is still a challenging issue in multi-hop wireless communications. In this paper, we propose a novel scheduling mechanism based on resource reservation for guaranteeing the QoS performance of real-time sessions (RTSNs) in IEEE 802.11e-based multi-hop wireless networks (MHWNs). Since RTSNs are sensitive to end-to-end delay in addition to their throughput requirements, our scheme defines a novel bandwidth reservation mechanism which guarantees resources to high priority services (i.e. RTSNs) for meeting both the delay and the throughput requirements. Moreover, the concurrent transmission (CT) mechanism implemented in the pre-configured contention-free period (CFP) further enhances the bandwidth utilization by means of letting chosen CT partners to transmit data simultaneously without collision. Simulation results show that the proposed scheduling mechanism significantly increases the efficiency of the bandwidth usage and successfully optimizes the QoS performance of RTSNs while providing fairness for other traffic sessions. © 2012 IEEE.
Grandblaise D, Moessner K, Leaves P, Bourse D (2003) Reconfigurability support for dynamic spectrum allocation: from the DSA concept to implementation, Proc. Joint First Workshop Mobile Future and Symp. Trends in Communications SympoTIC ?03 pp. 9-12
Moessner K, Georgoulas S (2011) Towards Efficient Protocol Design through Protocol Profiling and Performance Assessment: Using Formal Verification in a Different Context, Wiley International Journal of Communication Systems 25 (11)
The most common use of formal verification methods so far has been in identifying whether livelock and/or deadlock situations can occur during protocol execution, process, or system operation. In this work, we aim to show that an additional equally important and useful application of formal verification methods can be in protocol design in terms of performance-related metrics. This can be achieved by using the methods in a rather different context compared with their traditional use, that is, not only as model checking tools to assess the correctness of a protocol in terms of lack of livelock and deadlock situations but rather as tools capable of building profiles of protocol operations, assessing their performance, and identifying operational patterns and possible bottleneck operations. This process can provide protocol designers with an insight about the protocols' behavior and guide them toward further optimizations. It can also assist network operators and service providers to assess the protocols' relative performance and select the most suitable protocol for specific deployment scenarios. We illustrate these principles by showing how formal verification tools can be applied in this protocol profiling and performance assessment context using some existing protocol implementations in mobile and wireless environments as case studies. Copyright © 2011 John Wiley & Sons, Ltd.
Guo T, Moessner K (2012) Optimal strategy for QoS provision under spectrum mobility in cognitive radio networks, IEEE Vehicular Technology Conference
In cognitive radio networks, the arrival of Primary Users (PUs) may force Secondary Users (SUs) to terminate their ongoing sessions or degrade their Quality of Service (QoS) level. Given the time-varying spectrum availability, an immediate challenge arising is to support the QoS of SUs under spectrum mobility. In this paper, we propose an optimal decision-making framework for joint admission control, eviction control and bandwidth adaptation in cognitive radio networks. The problem is formulated as a Semi-Markov Decision Process (SMDP) and the optimal decision for each system state is derived to maximize the long-term network revenue as a function of the spectrum utilization, the SU blocking probability and the bandwidth adaptation cost under the SU dropping probability constraint. It is shown that the derived optimal strategy outperforms the threshold-based channel reservation schemes with/without bandwidth adaptation. And among the schemes with bandwidth adaptation, more performance improvement can be achieved by the proposed one when the bandwidth adaptation cost is taken into account. © 2012 IEEE.
Elsaleh T, Gluhak A, Moessner K (2011) Service continuity for subscribers of the mobile real world Internet, IEEE International Conference on Communications
The Real World Internet or the Web of Things has brought an approach to integrate wireless sensor devices in a manner that is natural to the Web, where sensors are exposed as addressable web resources like any other web resource. Although there is still a clear deficiency with regards to managing the mobility of the sensor devices in this approach, and how it affects the service and the users interacting with it. The work presented here addresses this issue and aims to provide an approach towards maintaining service continuity of migrating sensor devices in a framework that builds upon the concept of the 'Web of Things'. © 2011 IEEE.
Francois F, Wang N, Moessner K, Georgoulas S, De Oliveira Schmidt R (2014) Leveraging MPLS backup paths for distributed energy-aware traffic engineering, IEEE Transactions on Network and Service Management 11 (2) pp. 235-249
Backup paths are usually pre-installed by network operators to protect against single link failures in backbone networks that use multi-protocol label switching. This paper introduces a new scheme called Green Backup Paths (GBP) that intelligently exploits these existing backup paths to perform energy-aware traffic engineering without adversely impacting the primary role of these backup paths of preventing traffic loss upon single link failures. This is in sharp contrast to most existing schemes that tackle energy efficiency and link failure protection separately, resulting in substantially high operational costs. GBP works in an online and distributed fashion, where each router periodically monitors its local traffic conditions and cooperatively determines how to reroute traffic so that the highest number of physical links can go to sleep for energy saving. Furthermore, our approach maintains quality-of-service by restricting the use of long backup paths for failure protection only, and therefore, GBP avoids substantially increased packet delays. GBP was evaluated on the point-of-presence representation of two publicly available network topologies, namely, GÉANT and Abilene, and their real traffic matrices. GBP was able to achieve significant energy saving gains, which are always within 15% of the theoretical upper bound. © 2004-2012 IEEE.
Moessner K, Attou A (2008) Apparatus and Method for Performing Service Adaptation in Respect of a Mobile Computing Device,
Pozza R, Georgoulas S, Moessner K, Nati M, Gluhak A, Krco S (2016) An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT, Sensors 16 (11) 1852 MDPI
In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.
In this paper we present an analytical framework that aims to improve the energy efficiency of traffic offloading via Wireless Local Area Networks, taking into account the energy consumption for both data transmission and network discovery operations. More specifically, the network scanning period is optimized in order to minimize the energy consumption in a vehicular scenario where a user moves along a road covered by a long range cellular network and a number of randomly deployed Wireless Local Area Networks. The performance of the system that performs periodic network scanning with the optimal period is compared against a sub-optimal system that does not take into consideration the user and network context information when determining the network scanning period. According to performance evaluation results, the use of the optimal network scanning period achieves significant improvement in terms of energy consumption and network detection delay.
De S, Moessner K (2008) Method and apparatus for producing an ontology representing devices and services currently available to a device within a pervasive computing environment, USPTO 12/062,794
Akhtar N, Moessner K, Kernchen R (2006) Context dissemination for Autonomic Communication systems, AUTONOMIC COMMUNICATION 3854 pp. 237-242 SPRINGER-VERLAG BERLIN
Gürgen L, Biswas A-R, Moessner K, Ramparany F (2012) Welcome message from the chairs, Self-IoT'12 - Proceedings of the 2012 International Workshop on Self-Aware Internet of Things, Co-located with ICAC'12
Zhou Y, De S, Wang W, Moessner K (2016) Search Techniques for the Web of Things: A Taxonomy and Survey, SENSORS 16 (5) ARTN 600 MDPI AG
Chih-Lin I, Uusitalo MA, Moessner K (2015) The 5G Huddle, IEEE VEHICULAR TECHNOLOGY MAGAZINE 10 (1) pp. 28-31 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Grandblaise D, Moessner K, Vivier G, Tafazolli R (2005) Extended DCA paradigm for distributed licensed open spectrum coordination, Proc. IEEE 16th Int. Symp. Personal, Indoor and Mobile Radio Communications PIMRC 2005 3 pp. 1974-1978
Guo T, Wang N, Moessner K, Tafazolli R (2011) Shared backup network provision for virtual network embedding, IEEE International Conference on Communications
Network virtualization has been recognized as a promising solution to enable the rapid deployment of customized services by building multiple Virtual Networks (VNs) on a shared substrate network. Whereas various VN embedding schemes have been proposed to allocate the substrate resources to each VN requests, little work has been done to provide backup mechanisms in case of substrate network failures. In a virtualized infrastructure, a single substrate failure will affect all the VNs sharing that resource. Provisioning a dedicated backup network for each VN is not efficient in terms of substrate resource utilization. In this paper, we investigate the problem of shared backup network provision for VN embedding and propose two schemes: shared on-demand and shared pre-allocation backup schemes. Simulation experiments show that both proposed schemes make better utilization of substrate resources than the dedicated backup scheme without sharing, while each of them has its own advantages. © 2011 IEEE.
Dianati M, Tafazolli R, Moessner K (2010) Enabling Tussle-Agile Inter-networking Architectures by Underlay Virtualisation, FUTURE INTERNET - FIS 2009 6152 pp. 81-95 SPRINGER-VERLAG BERLIN
Ibrahim A, Carrez F, Moessner K (2015) Geospatial Ontology-based Mission Assignment in Wireless Sensor Networks, 2015 INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN INTERNET OF THINGS (RIOT) IEEE
Murroni M, Venkatesha Prasad R, Marques P, Bochow B, Noguet D, Sun C, Harada H, Moessner K (2011) IEEE 1900.6: Spectrum Sensing
Interfaces and Data Structures for
Dynamic Spectrum Access and
Other Advanced Radio Communication
Systems Standard:
Technical Aspects and Future Outlook,
IEEE Communications Magazine 49 (12) pp. 118-127 IEEE
Currently, the IEEE Standards Association is very active in the framework of cognitive radio with an aim to provide a bridge between research results, implementation, and widespread deployment of this new communication paradigm. This article reports recent developments within the IEEE Dynamic Spectrum Access Network Standards Committee1 on dynamic spectrum access networks with particular consideration of IEEE 1900.6, ??Spectrum Sensing Interfaces and Data Structures for Dynamic Spectrum Access and Other Advanced Radio Communication Systems.?? It outlines the current structure of the IEEE 1900.6 standard and its relationship with other related standardization activities. We provide application scenarios and topology briefly, and discuss open research issues that raise future challenges to the standardization community.
Moessner K, Luo J, Mohyeldin E, Grandblaise D, Kloeck C, Martoyo I, Sallent O, Demestichas P, Dimitrakopoulos G, Tsagkaris K, Olaziregi N (2006) Functional Architecture of End-to-End Reconfigurable Systems, 2006 IEEE 63RD VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6 pp. 196-200 IEEE
Barnaghi P, Liu X, Moessner K, Liao J (2010) Using Concept and Structure Similarities for Ontology Integration, CEUR Workshop Proceedings: Proceedings of the 5th International Workshop on Ontology Matching 689
We propose a method to align different ontologies in similar
domains and then define correspondence between concepts in two
different ontologies using the SKOS model.
Alnwaimi G, Arshad K, Moessner K (2011) Dynamic spectrum allocation algorithm with interference management in displaced networks, IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference pp. 941-946
Dynamic spectrum allocation (DSA) has been cited as a promising mechanism for managing the radio spectrum for coexisting systems. The goal of the DSA scheme is to increase the performance of networks in the shared spectrum, by providing a more efficient way of utilisation. This work addresses analytically the impact of multi-cell, multi-operator interference on the overall spectrum when multiple operators co-exist and share a common pool of radio resources. We propose a centralised DSA scheme that is able to capture the interference level and interact dynamically to minimise interference and enhance spectrum utilisation while maintaining a satisfactory level of QoS. Furthermore, a concise system model and framework able to describe the interaction among different operators is presented. The DSA algorithm has been investigated for co-located and displaced cellular networks. The simulation results indicate that the proposed DSA algorithm significantly outperforme the fixed spectrum allocation (FSA) ensuring minimum level of interference in the system. The QoS of the overall system has been improved in the DSA compared to traditional FSA. Moreover, the proposed algorithm enhanced the spectrum utilization by 26% guaranteeing that all operators are given fair access to the shared spectrum. © 2011 IEEE.
Wang W, De S, Cassar G, Moessner K (2013) Knowledge Representation in the Internet of Things: Semantic Modelling and its Applications, Automatika ? Journal for Control, Measurement, Electronics, Computing and Communications 54 (4) pp. 388-400 KoREMA
Semantic modelling provides a potential basis for interoperating among different systems and applications in
the Internet of Things (IoT). However, current work has mostly focused on IoT resource management while not
on the access and utilisation of information generated by the ?Things?. We present the design of a comprehensive
and lightweight semantic description model for knowledge representation in the IoT domain. The design follows
the widely recognised best practices in knowledge engineering and ontology modelling. Users are allowed to
extend the model by linking to external ontologies, knowledge bases or existing linked data. Scalable access to IoT
services and resources is achieved through a distributed, semantic storage design. The usefulness of the model is
also illustrated through an IoT service discovery method.
Guo T, Wang N, Tafazolli R, Moessner K (2010) Policy-Aware Virtual relay placement for inter-domain path diversity, Proc. IEEE Symp. Computers and Communications (ISCC) pp. 38-43
Lopez-Benitez M, Moessner K (2013) LTE uplink extension in TV white spaces, 19th European Wireless Conference, EW 2013
Dynamic Spectrum Access (DSA)/Cognitive Radio (CR) represents a promising and versatile concept to improve the efficiency of spectrum exploitation by allowing unlicensed users to opportunistically access underutilised licensed bands, provided that no harmful interference is caused to the legitimate (licensed) users of the spectrum. This revolutionary spectrum access paradigm can be exploited not only to deploy new radio systems and technologies in the already allocated spectrum, but also to increase the capacity of existing systems. A good example of this application is the extension of Long Term Evolution (LTE) cellular systems in Television (TV) white spaces (i.e., TV channels not used in a certain region), which has received significant attention. Most of the existing studies, however, have focused on the extension of the LTE downlink component. By contrast, this work complements previous studies by considering the LTE uplink component in TV white spaces. By means of system-level simulations, this work analyses the conditions under which such coexistence is feasible and the underlying implications. © VDE VERLAG GMBH.
Cassar G, Barnaghi P, Moessner K (2013) Probabilistic Matchmaking Methods for Automated Service Discovery, IEEE Transactions on Service Computing
Automated service discovery enables human users or software agents to form queries and to search and discover the services based on different requirements. This enables implementation of high-level functionalities such as service recommendation, composition, and provisioning. The current service search and discovery on the Web is mainly supported by text and keyword based solutions which offer very limited semantic expressiveness to service developers and consumers. This paper presents a method using probabilistic machine-learning techniques to extract latent factors from semantically enriched service descriptions. The latent factors are used to construct a model to represent different types of service descriptions in a vector form. With this transformation, heterogeneous service descriptions can be represented, discovered, and compared on the same homogeneous plane. The proposed solution is scalable to large service datasets and provides an efficient mechanism that enables publishing and adding new services to the registry and representing them using latent factors after deployment of the system. We have evaluated our solution against logic-based and keyword-based service search and discovery solutions. The results show that the proposed method performs better than other solutions in terms of precision and normalised discounted cumulative gain values.
Akhtar N, Markendahl J, Moessner K (2007) Analysis of complexity and transaction costs for cooperating networks, 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9 pp. 4270-4274 IEEE
Francois F, Wang N, Moessner K, Georgoulas S (2012) Optimization for time-driven link sleeping reconfigurations in ISP backbone networks, Proceedings of the 2012 IEEE Network Operations and Management Symposium, NOMS 2012 pp. 221-228
Backbone network energy efficiency has recently become a primary concern for Internet Service Providers and regulators. The common solutions for energy conservation in such an environment include sleep mode reconfigurations and rate adaptation at network devices when the traffic volume is low. It has been observed that many ISP networks exhibit regular traffic dynamicity patterns which can be exploited for practical time-driven link sleeping configurations. In this work, we propose a joint optimization algorithm to compute the reduced network topology and its actual configuration duration during daily operations. The main idea is first to intelligently remove network links using a greedy heuristic, without causing network congestion during off-peak time. Following that, a robust algorithm is applied to determine the window size of the configuration duration of the reduced topology, making sure that a unified configuration with optimized energy efficiency performance can be enforced exactly at the same time period on a daily basis. Our algorithm was evaluated using on a Point-of-Presence representation of the GÉANT network and its real traffic matrices. According to our simulation results, the reduced network topology obtained is able to achieve 18.6% energy reduction during that period without causing significant network performance deterioration. The contribution from this work is a practical but efficient approach for energy savings in ISP networks, which can be directly deployed on legacy routing platforms without requiring any protocol extension. © 2012 IEEE.
De S, Meissner S, Kernchen R, Moessner K (2008) A Semantic Device and Service Description Framework for Ubiquitous Environments, ICT-MobileSummit 2008 Conference Proceedings IIMC International Information Management Corporation
Arshad K, Moessner K (2013) Robust Collaborative Spectrum Sensing in the
Presence of Deleterious Users,
IET Communications 7 (1) pp. 49-56 IET
Collaborative spectrum sensing has attracted significant research attention in the last few years and is widely accepted as a viable approach to improve spectrum sensing reliability. Fusing data from multiple Opportunistic users (OUs) in order to produce reliable sensing results implies a reliance on the OU to provide correct information. In the presence of malfunctioning or selfish users, performance of collaborative spectrum sensing
deteriorates significantly. In this article, we propose mechanisms for the detection and suppression of such deleterious opportunistic users (DOUs) for hard and soft decision fusion. More specifically, a credibility based
mechanism for hard decision fusion using a beta reputation system (HDC-BR) is introduced. Our proposed method does not require knowledge of the total number of deleterious users in advance. In HDC-BR, the fusion center assigns and updates weights to each user?s decisions based on an individual user credibility score which is calculated using the beta reputation system. The presence of DOUs in soft decision based collaborative spectrum sensing has even more adverse effects on system performance. We also propose a scheme for the case of soft
decision fusion to detect and eliminate falsified user observations at the fusion centre using a Modified Grubbs Test; we refer to it as SDC-MG. We compare the performance of the proposed methods with malicious user
detection schemes proposed in the literature as well as with the case where no DOU suppression scheme is implemented, and conclude that SDC-MG performs much better than HDC-BR in a low Signal to Noise Ratio (SNR) regime.
Tarkoma S, Prehofer C, Zhdanova AV, Moessner K, Kovacs E (2007) SPICE: Evolving IMS to next generation service platforms, SAINT - 2007 International Symposium on Applications and the Internet - Workshops, SAINT-W
Today's wireless and mobile services are typically monolithic and often centralized in nature, which limits heterogeneous service access and shared service usage. New sources of revenue for providers are expected to include tailored, personalized, and dynamically composed services that are fast to market, cost efficient, and provide compelling user experience. To meet these market needs, the SPICE service platform extends the IP Multimedia Subsystem (IMS) by supporting added-value services that are composed of more basic services. The platform is presented through the architecture and through scenarios showing the interactions between the platform and its service components. We describe the IMS role and functions in SPICE, and the use of ontology and Semantic Web technologies for integrated knowledge management in such mobile service platforms. © 2007 IEEE.
Jin Y, Wei D, Vural S, Gluhak A, Moessner K (2011) A distributed energy-efficient re-clustering solution for wireless sensor networks, GLOBECOM - IEEE Global Telecommunications Conference
Clustering algorithms are widely used in Wireless Sensor Networks (WSNs), which however incurs significant energy consumption at Cluster Headers(CHs). Therefore, a re-clustering operation is typically used to balance the workload, where different CHs are selected and clusters are reorganized. However, a considerable number of control messages is initiated during this process which inevitably consumes on-board node energy. Hence, the question of how often the network should perform the re-clustering operation needs to be addressed. In this paper, a distributed re-clustering solution is proposed, which provides an energy-efficient re-clustering rate to conserve node energy while also equalizing the node energy consumption across the network. The proposed algorithm calculates the approximate amount of energy required to reorganize the clusters and to deliver the sensory data. By properly predicting the levels of the energy consumptions values, the appropriate frequency of performing the re-clustering operation can be determined, which reduces control message overhead. To the best of our knowledge, this is the first work that analytically analyzes the overhead in re-clustering a WSN, groups re-clustering rounds to reduce this overhead, and simultaneously equalizes node lifetimes. Performance results show that the proposed algorithm outperforms two other popular clustering algorithms in node energy conservation and node lifetime equalization. © 2011 IEEE.
Nati M, Gluhak A, Domaszewicz J, Lalis S, Moessner K (2014) Lessons from SmartCampus: External Experimenting with User-Centric Internet-of-Things Testbed, Wireless Personal Communications
© 2014 Springer Science+Business Media New YorkCreating Internet-of-Things (IoT) solutions that can be deployed at scale requires adequate experimentation environments. In the area of experimentation, two trends can be observed. First, there is a shift from lab-based, controlled experiments to experimenting ?in the wild?: researchers tend to augment the users? natural environments and observe how people integrate a new solution into their everyday lives. Second, when a substantial investment in setting up an experimentation infrastructure has been made, it makes sense to open it to a wide community of researchers; the concept of Experimentation-as-a-Service (EaaS) is emerging along these lines. SmartCampus, an IoT testbed developed at the University of Surrey, fits the both trends very well. It involves real users in a natural setting, as IoT devices are deployed in the users? offices. Further, several user-centric experiments conducted in the SmartCampus were driven by external researchers, i.e., people who do not belong to the team that developed the testbed. In this paper we report on lessons learned from such IoT experiments. After a brief overview of SmartCampus and the experiments themselves, we offer a simple experiment stakeholder model, which identifies key actors and interfaces between them. We then focus on issues related to the external experimenters who take advantage of the experimentation ?service.? That focus is motivated by our realization that EaaS, while attractive in principle, gives rise to a number of non-trivial challenges.
Alnwaimi G, Vahid S, Moessner K (2015) Distributed Learning Game based Spectrum Sharing and Resource Selection for Femtocells, 2015 22ND INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT) pp. 331-337 IEEE
Rai MR, Vahid S, Moessner K (2015) SINR based Topology Control for Multihop Wireless Networks with Fault Tolerance, 2015 IEEE 81ST VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING) IEEE
Baldini G, Prasad RRV, Biswas AR, Moessner K, Etelapera M, Soininen J-P, Nechifor D-C, Stavroulaki V, Vlacheas P (2012) A cognitive management framework to support exploitation of the future internet of things, Scalable Computing 13 (2) pp. 139-147
In this article, a cognitive management framework is proposed for ensuring exploitation of the Future Internet of Things (FIoT). Cognitive systems offer self-x and learning. A cognitive system has the ability to dynamically select its behavior through self-management/awareness functionality, taking into account information and knowledge on the context of the operations as well as policies and including the generation of the context itself. The framework is based on the principle that any real world object and any digital object that is available, accessible, observable or controllable can have a virtual representation in the Future Internet, which is called Virtual Object (VO). Basic VOs can be composed in a more sophisticated way by forming Composite VOs (CVOs), which provide services to high-level applications and end-users. The described paradigm is applied to various applications scenarios: smart home, smart office, smart city and smart business. This paper presents some background in IoT, identifies the requirements and challenges, and sets the directions that should be followed. © 2012 SCPE.
Demestichas P, Dimitrakopoulos G, Mößner K, Dodgson T, Bourse D, Stavroulaki V, Malamateniou F, Katidiotis A, Tsagkaris K, El Khazen K, Grandblaise D, Beaujean C, Buljore S, Roux P, Vivier G, Hope S, Brakensiek J, Lenz D, Lucking U, Steinke B, Aghvami H, Olaziregi N, Holland O, Fan Q, Alonistioti N, Foukalas F, Kafounis K, Kaloxylos A, Stamatelatos M, Boufidis Z, Hoffmeyer J, Dillinger M, Mohyeldin E, Luo J, Schulz E, Falk R, Menzel C, Agusti R, Sallent O, Alvarez M, Garcia-Perez R, Campoy LM, Vila JE, Warzansky W, Bakaimis BA, Berlemann L, Mirkovic J, Bisiaux A, de Baynast A, Joseph MC, Cavallaro R, Radosavljevic P, Delautre A, Goubard JE, Farnham T, Zhong S, Dolwin C, Dornbush P, Fahrmair M, Gultchev S, Halimic M, Patel S, Naveen S, Vogler J, Pfeiffer G, Berzosa F, Wiebke T, Prehofer C, Wei Q, Pulou J, Stuckmann P, Cordier P, Lugara D, Ravasio G (2006) Reconfigurability, 2 pp. 313-421
Jin Y, Jin J, Gluhak A, Moessner K, Palaniswami M (2011) An Intelligent Task Allocation Scheme for Multi-hop Wireless Networks, IEEE Transactions on Parallel and Distributed Systems 23 (3) pp. 444-451 IEEE Computer Society
Emerging applications in Multi-hop Wireless Networks (MHWNs) require considerable processing power which often may be beyond the capability of individual nodes. Parallel processing provides a promising solution, which partitions a program into multiple small tasks and executes each task concurrently on independent nodes. However, multi-hop wireless communication is inevitable in such networks and it could have an adverse effect on distributed processing. In this paper, an adaptive intelligent task mapping together with a scheduling scheme based on a genetic algorithm is proposed to provide real-time guarantees. This solution enables efficient parallel processing in a way that only possible node collaborations with cost-effective communications are considered. Furthermore, in order to alleviate the power scarcity of MHWN, a hybrid fitness function is derived and embedded in the algorithm to extend the overall network lifetime via workload balancing among the collaborative nodes, while still ensuring the arbitrary application deadlines. Simulation results show significant performance improvement in various testing environments over existing mechanisms.
Akbar A, Nati M, Carrez F, Moessner K (2015) Contextual Occupancy Detection for Smart Office by Pattern Recognition of Electricity Consumption Data, 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) pp. 561-566 IEEE
Palaghias N, Hoseinitabatabaei SA, Nati M, Gluhak A, Moessner K (2016) A Survey on Mobile Social Signal Processing, ACM COMPUTING SURVEYS 48 (4) ARTN 57 ASSOC COMPUTING MACHINERY
Poncela J, Vlacheas P, Giaffreda R, De S, Vecchio M, Nechifor S, Barco R, Aguayo-Torres MC, Stavroulaki V, Moessner K, Demestichas P (2014) Smart cities via data aggregation, Wireless Personal Communications 76 (2) pp. 149-168
Cities have an ever increasing wealth of sensing capabilities, recently including also internet of things (IoT) systems. However, to fully exploit such sensing capabilities with the aim of offering effective city-sensing-driven applications still presents certain obstacles. Indeed, at present, the main limitation in this respect consists of the vast majority of data sources being served on a "best effort" basis. To overcome this limitation, we propose a "resilient and adaptive IoT and social sensing platform". Resilience guarantees the accurate, timely and dependable delivery of the complete/related data required by smart-city applications, while adaptability is introduced to ensure optimal handling of the changing requirements during application provision. The associated middleware consists of two main sets of functionalities: (a) formulation of sensing requests: selection and discovery of the appropriate data sources; and (b) establishment and control of the necessary resources (e.g., smart objects, networks, computing/storage points) on the delivery path from sensing devices to the requesting applications. The middleware has the intrinsic feature of producing sensing information at a certain level of detail (geographical scope/timeliness/accuracy/completeness/ dependability) as requested by the applications in a given domain. The middleware is assessed and validated at a proof-of-concept level through innovative, dependable and real-time applications expected to be highly reproducible across different cities. © 2014 Springer Science+Business Media New York.
Leaves P, Moessner K, Tafazolli R, Grandblaise D, Bourse D, Tonjes R, Breveglieri M (2004) Dynamic spectrum allocation in composite reconfigurable wireless networks, IEEE_M_COM 42 5 pp. 72-81
Du Y, Kertichen R, Moessner K, Raeck C, Sawade O, Tarkoma S, Arbanowski S (2007) Context-aware learning for intelligent mobile multimodal user interfaces, 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9 pp. 3672-3676 IEEE
Georgoulas S, Moessner K, Mcaleer B, Tafazolli R (2010) Using formal verification methods and tools for protocol profiling and performance assessment in mobile and wireless environments, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC pp. 2471-2476
The most common use of formal verification methods and tools so far has been in identifying whether livelock and/or deadlock situations can occur during protocol execution, process, or system operation. In this work we aim to show that an additional equally important and useful application of formal verification tools can be in protocol design and protocol selection in terms of performance related metrics. This can be achieved by using the tools in a rather different context compared to their traditional use. That is not only as model checking tools to assess the correctness of a protocol in terms of lack of livelock and deadlock situations but rather as tools capable of building profiles of protocol operations, assessing their performance, and identifying operational patterns and possible bottleneck operations. This process can provide protocol designers with an insight about the protocols' behavior and guide them towards further protocol design optimizations. It can also assist network operators and service providers in selecting the most suitable protocol for specific network and service configurations. We illustrate these principles by showing how formal verification tools can be applied in this protocol profiling and performance assessment context using some existing protocols as case studies. ©2010 IEEE.
Alnwaimi G, Zahir T, Vahid S, Moessner K (2013) Machine learning based knowledge acquisition on spectrum usage for LTE femtocells, IEEE Vehicular Technology Conference
The decentralised and ad hoc nature of femtocell deployments calls for distributed learning strategies to mitigate interference. We propose a distributed spectrum awareness scheme for femtocell networks, based on combined payoff and strategy reinforcement learning (RL) models. We present two different learning strategies, based on modifications to the Bush Mosteller (BM) RL and the Roth-Erev RL algorithms. The simulation results show the convergence behaviour of the learning strategies under a dynamic robust game. As compared to the Bush Mosteller (BM) RL, our modified BM (MBM) converges smoothly to a stable satisfactory solution. Moreover, the MBM significantly reduces the interference collision cost during the learning process. Both the MBM and the modified Roth-Erev (MRE) algorithms are stochastic-based learning strategies which require less computation than the gradient follower (GF) learning strategy and have the capability to escape from suboptimal solution. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.
Marques P, Rodriguez J, Delaere S, Delahaye P, Lecroart B, Gundlach M, Triantafyllopoulou D, Moessner K, Noguet D (2013) Spectrum sharing in the EU and the path towards standardization,
This paper addresses the current regulatory framework, research activities and standardization efforts towards a shared use of radio spectrum in the European Union. Two main research streams are considered: The emerging concept of Licensed Shared Access that ensures a predictable Quality of Service for secondary users of spectrum and the opportunistic Device-to-Device communications that represent a recent and enormous socio-technological trend. The paper presents also research results that support the spectrum sharing standardization path in ETSI and 3GPP.
Foteinos V, Kelaidonis D, Poulios G, Stavroulaki V, Vlacheas P, Demestichas P, Giaffreda R, Biswas AR, Menoret S, Nguengang G, Etelapera M, Septimiu-Cosmin N, Roelands M, Visintainer F, Moessner K (2013) A cognitive management framework for empowering the internet of things, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 7858 LNCS pp. 187-199
This work presents a Cognitive Management framework for empowering the Internet of Things (IoT). This framework has the ability to dynamically adapt its behaviour, through self-management functionality, taking into account information and knowledge (obtained through machine learning) on the situation (e.g., internal status and status of environment), as well as policies (designating objectives, constraints, rules, etc.). Cognitive technologies constitute a unique and efficient approach for addressing the technological heterogeneity of the IoT and obtaining situation awareness, reliability and efficiency. The paper also presents a first indicative implementation of the proposed framework, comprising real sensors and actuators. The preliminary results of this work demonstrate high potential towards self-reconfigurable IoT. © The Author(s).
Yu X, Navaratnam P, Moessner K (2010) Distributed Resource Reservation Mechanism for IEEE 802.11e-Based Networks, Proc. IEEE 72nd Vehicular Technology Conf. Fall (VTC 2010-Fall) pp. 1-5
AlShahwan F, Moessner K, Carrez F (2011) Providing light weight distributed web services from mobile hosts, Proceedings - 2011 IEEE 9th International Conference on Web Services, ICWS 2011 pp. 652-659
Providing non interrupted Web Services from resource limited mobile devices needs to be done in a rather light-weight manner. Processing and communication will drain the battery rapidly; hence, both should be kept at a minimum. This paper describes the outcomes of an investigation into simple offloading mechanisms that facilitate provision of adaptive and distributed RESTful mobile web services from resource constrained mobile devices. Offloading considers the distributed hosts processing as well as communication capabilities. Using queuing theory, the performance gained from distributing mobile web service tasks is explored. In addition, the theoretical boundaries of different flavours of offloading mechanisms are presented. The analytical, as well as the experimental results show the differences in performance between these mechanisms. © 2011 IEEE.
Durowoju O, Arshad K, Moessner K (2011) Distributed power control for cognitive radio networks, based on incumbent outage information, IEEE International Conference on Communications
The interference management problem in cognitive radio networks is in this paper, tackled from the transmitter power control perspective so that transmissions by cognitive radios does not violate the interference level thresholds at incumbent users. We modify cellular distributed power control algorithms to suit the cognitive radio framework by exploiting spectrum use and radio environment knowledge for incumbent user location estimation in worst-case scenario. Most literature employs worst-case analysis to guarantee robustness thereby trading off optimality. We therefore, propose a stochastic approach which allows the cognitive radio network, access the extra capacity based on incumbent user outage information with guarantees on interference protection to the incumbent user at all times. This paper therefore shows that the proposed distributed power control strategy is robust with the benefit of increased spectral efficiency compared to its worst case counterpart. © 2011 IEEE.
Prammanee S, Moessner K, Tafazolli R (2006) Discovering modalities for adaptive multimodal interfaces, Interactions 13 (3) pp. 66-70 ACM
Ibrahim A, Carrez F, Moessner K (2013) Spatio-Temporal Model for Role Assignment in Wireless Sensor Networks., EW VDE-Verlag
AlShahwan F, Moessner K, Carrez F (2010) Evaluation of Distributed SOAP and RESTful MobileWeb Services, International Journal on Advances in Networks and Services 3 (3 & 4) pp. 447-461 IARIA
Even mobile Web Services are still provided using
servers that usually reside in the core networks. Main reason
for not providing large and complex Web Services from
resource limited mobile devices is not only the volatility of
wireless connections and mobility of mobile hosts, but also, the
often limited processing power. Offloading of some of the
processing tasks is one step towards achieving optimal mobile
Web Service provision. This paper presents two frameworks
for providing distributed mobile Web Services: One mobile
service provision framework is built on Simple Object Access
Protocol (SOAP), while the other implements Representational
State Transfer (REST) architecture. Both frameworks have
been extended with offloading functionality and different types
of resource intensive operations, i.e., process intensive and
bandwidth intensive services, have been tested. The results
show that using a REST-based framework leads of a better
performing offloading behaviour, compared to SOAP-based
mobile services. Distributed mobile services based on REST
consume fewer resources and achieve better performance
compared to SOAP based mobile services. The paper describes
the approach, evaluation method and findings.
Moessner K, Vahid S, Tafazolli R (1999) A minimum air interface implementation for software radio based on distributed object technology, Proc. IEEE Int Personal Wireless Communication Conf pp. 369-373
Attou A, Ding J, Laurenson DI, Moessner K (2008) Performance Modelling and Evaluation of An Adaptation Management System, PROCEEDINGS OF THE 2008 INTERNATIONAL SYMPOSIUM ON PERFORMANCE EVALUATION OF COMPUTER AND TELECOMMUNICATION SYSTEMS pp. 369-376 SOC MODELING SIMULATION INT-SCS
Yu X, Navaratnam P, Moessner K, Cruickshank H (2015) Distributed Resource Reservation in Hybrid MAC With Admission Control for Wireless Mesh Networks, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 64 (12) pp. 5891-5903 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Moessner K, Tafazolli R (2000) Terminal reconfigureability-the software download aspect, Proc. First Int 3G Mobile Communication Technologies Conf. (Conf. Publ. No. 471) pp. 326-330
Demestichas P, Moessner K, Smirnov M, Bourse D (2010) Functionality and Collaboration Mechanisms for Cognitive Wireless Networks and Systems, JOURNAL OF NETWORK AND SYSTEMS MANAGEMENT 18 (1) pp. 1-3 SPRINGER
Zhdanova AV, Davies M, Jorns O, Stavroulaki V, Demestichas P, Gonzalez M, Moessner K, Carrez F, Rajasekaran H, Iacono LL (2008) MOSS: Mobile social spaces, CEUR Workshop Proceedings 409
We present an emerging approach of Mobile Social Spaces (MOSS) that intends to improve the ways in which people communicate in the modern world. Pervasive content and service creation and provisioning, in particular for dynamically changing social groups, is a complex task and subject to varying locations of individuals, of the complete group and its context. MOSS tries to remove some of the obstacles in this area and defines a range of functionalities that will support dynamic ubiquitous creation and instantiation of community content and services.
Arshad K, Imran MA, Moessener K (2010) Collaborative Spectrum Sensing Optimisation Algorithms for Cognitive Radio Networks, International Journal of Digital Multimedia Broadcasting 2010 Article ID 424036 Hindawi Publishing Corporation
The main challenge for a cognitive radio is to detect the existence of primary users reliably in order to minimise the interference to licensed communications. Hence, spectrum sensing is a most important requirement of a cognitive radio. However, due to the channel uncertainties, local observations are not reliable and collaboration among users is required. Selection of fusion rule at a common receiver has a direct impact on the overall spectrum sensing performance. In this paper, optimisation of collaborative spectrum sensing in terms of optimum decision fusion is studied for hard and soft decision combining. It is concluded that for optimum fusion, the fusion centre must incorporate signal-to-noise ratio values of cognitive users and the channel conditions. A genetic algorithm-based weighted optimisation strategy is presented for the case of soft decision combining. Numerical results show that the proposed optimised collaborative spectrum sensing schemes give better spectrum sensing performance.
Barnaghi P, Moessner K, Presser M, Meissner S (2009) Smart Sensing and Context, Springer
This volume constitutes the revised papers of the 4th European Conference on Smart Sensing and Context, Euro SSC 2009, held in Guilford, UK, in September 2009.This volume consists of 16 full papers.
El Saddik A, Moessner K, Selçuk Candan K, Liang B, Liu J (2008) ACM/springer mobile networks and applications (MONET): Special issue on "ambient media and systems", Mobile Networks and Applications 13 (6) pp. 543-546
Akbar A, Khan A, Carrez F, Moessner K (2017) Predictive Analytics for Complex IoT Data Streams, IEEE Internet of Things 4 (5) pp. 1571-1582 IEEE
The requirements of analyzing heterogeneous data
streams and detecting complex patterns in near real-time have
raised the prospect of Complex Event Processing (CEP) for many
internet of things (IoT) applications. Although CEP provides
a scalable and distributed solution for analyzing complex data
streams on the fly, it is designed for reactive applications as CEP
acts on near real-time data and does not exploit historical data.
In this regard, we propose a proactive architecture which exploits
historical data using machine learning (ML) for prediction
in conjunction with CEP. We propose an adaptive prediction
algorithm called Adaptive Moving Window Regression (AMWR)
for dynamic IoT data and evaluated it using a real-world use
case with an accuracy of over 96%. It can perform accurate
predictions in near real-time due to reduced complexity and
can work along CEP in our architecture. We implemented our
proposed architecture using open source components which are
optimized for big data applications and validated it on a use-case
from Intelligent Transportation Systems (ITS). Our proposed
architecture is reliable and can be used across different fields
in order to predict complex events.
O?Reilly C, Moessner K, Nati M (2017) Univariate and Multivariate Time Series Manifold Learning, Knowledge-Based Systems 133 pp. 1-16 Elsevier
Time series analysis aims to extract meaningful information from data that has been generated in sequence by a dynamic
process. The modelling of the non-linear dynamics of a signal is often performed using a linear space with a similarity
metric which is either linear or attempts to model the non-linearity of the data in the linear space. In this research, a
different approach is taken where the non-linear dynamics of the time series are represented using a phase space. Training
data is used to construct the phase space in which the data lies on or close to a lower-dimensional manifold. The basis
of the non-linear manifold is derived using the kernel principal components derived using kernel principal component
analysis where fewer components are retained in order to identify the lower-dimensional manifold. Data instances are
projected onto the manifold, and those with a large distance between the original point and the projection are considered
to be derived from a different underlying process. The proposed algorithm is able to perform time series classification
on univariate and multivariate data. Evaluations on a large number of real-world data sets demonstrate the accuracy of
the new algorithm and how it exceeds state-of-the-art performance.
Godarzi DM, Arshad K, Ko Y, Moessner K (2012) Selecting users in energy-efficient collaborative spectrum sensing, IEEE Wireless Communications and Networking Conference, WCNC pp. 1029-1033
Cognitive radio network is defined as an intelligent wireless communication network that should be able to adaptively reconfigure its communication parameters to meet the demands of the transmission network or the user. In this context one possible way to utilize unused licensed spectrum without interfering with incumbent users is through spectrum sensing. Due to channel uncertainties, single cognitive (opportunistic) user cannot make a decision reliably and hence collaboration among multiple users is often required. Here collaboration among large number of users tends to increase power consumption and introduces large communication overheads. In this paper, the number of collaborating users is optimized in order to maximize the probability of detection for any given power budget in a cognitive radio network, while satisfying constraints on the false alarm probability. We show that for the maximum probability of detection, collaboration of only a subset of available opportunistic users is required. The robustness of our proposed spectrum sensing algorithm is also examined under flat Rayleigh fading and AWGN channel conditions. © 2012 IEEE.
Wei D, Jin Y, Vural S, Moessner K, Tafazolli R (2011) An Energy-efficient Clustering Solution for Wireless Sensor Networks, Transactions on Wireless Communications PP (99) pp. 1-11 IEEE
Hot spots in a wireless sensor network emerge
as locations under heavy traffic load. Nodes in such areas quickly deplete energy resources, leading to disruption in network services. This problem is common for data collection scenarios in
which Cluster Heads (CH) have a heavy burden of gathering and relaying information. The relay load on CHs especially intensifies as the distance to the sink decreases. To balance the traffic load and the energy consumption in the network, the CH role should be rotated among all nodes and the cluster sizes should be carefully determined at different parts of the network.
This paper proposes a distributed clustering algorithm, Energy-efficient Clustering (EC), that determines suitable cluster sizes depending on the hop distance to the data sink, while achieving approximate equalization of node lifetimes and reduced energy consumption levels. We additionally propose a simple
energy-efficient multihop data collection protocol to evaluate the effectiveness of EC and calculate the end-to-end energy consumption of this protocol; yet EC is suitable for any data collection protocol that focuses on energy conservation. Performance results demonstrate that EC extends network lifetime and achieves energy equalization more effectively than two well-known clustering algorithms, HEED and UCR.
Mcaleer B, Georgoulas S, Moessner K, Tafazolli R (2011) Evaluating protocol energy use and efficiency through profiling of computational operations, IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference pp. 930-935
With the exponential growth of internet communications and the rise to prominence of environmental concerns, the energy consumption of the Information Communications Technology industry has become an issue of major importance. One area that has not been yet fully explored is the evaluation of the computational loads required in the processing and forwarding of traffic. While significant work has been performed towards optimizations especially of wireless protocols for energy efficiency "outside the devices" through energy-optimizing mechanisms that deal with the characteristics of the transmission medium, the computational loads required by the protocols' operations and mechanisms themselves within the devices have not been yet investigated adequately. Towards this end, in this paper we put forward a method suitable for the measurement and profiling of the processing requirements of the operations, as well as for the traffic loads, generated by both wired and wireless protocols. As we show, this method can be used to determine specific operations, functionality sets and configurations that increase the protocols' and the resulting overall network energy use. It can be used, therefore, to derive recommendations for further protocol optimizations towards energy efficiency as well as practical rules for the selection of specific protocols depending on the higher level applications and the specific deployment environment under which they operate. © 2011 IEEE.
Lee H, Vahid S, Moessner K (2012) Utility-based dynamic spectrum aggregation algorithm in cognitive radio networks, IEEE Vehicular Technology Conference
In this paper, we propose a utility-based spectrum aggregation algorithm to enhance the performance of a cognitive radio network considering multiple objectives: (i) maximization of overall throughput, (ii) reduction of channel switching, (iii) reducing the number of sub-channels comprising the aggregate channel, aimed at opportunistic spectrum use by secondary users (SUs). These three objectives are integrated into a weighted sum utility function. The weight associated with each objective can be set differently (typically done manually) depending on the metric to be optimized. In this article however, we propose and evaluate an automatic mechanism for setting weights. The proposed algorithm including the learning module allows for automated (no manual intervention) adaptable setting of objective- function weights depending on the environment changes and its performance is also shown via the simulation results. © 2012 IEEE.
Tönjes R, Reetz ES, Moessner K, Barnaghi PM (2012) A test-driven approach for life cycle management of internet of things enabled services, 2012 Future Network and Mobile Summit, FutureNetw 2012
To date implementations of Internet of Things (IoT) architectures are confined to particular application areas and tailored to meet only the limited requirements of their narrow applications. To overcome technology and sector boundaries this paper proposes a dynamic service creation environment that employs i) orchestration of business services based on re-usable IoT service components, ii) self-management capable components for automated configuration and testing of services for things, and iii) abstraction of the heterogeneity of underlying technologies to ensure interoperability. To ensure reliability and robustness the presented approach integrates self-testing and self-adaptation in all service life cycle phases. The service life cycle management distinguishes the IoT service creation phase (design-time) and the IoT service provision phase (run-time). For test-friendly service creation (1) semantic service descriptions are employed to derive semi-automatically services and related tests, (2) and testing is systematically integrated into a Service Creation Environment. For reliable and robust service provisioning the presented system (3) forces validation tests in a sandbox environment before deployment and (4) enables run-time monitoring for service adaptation. The system under test is modelled by finite state machines (FSM) that are semi-automatically composed of re-usable test components. Then path searching algorithms are applied to derive automatically tests from the FSM model. The resulting tests are specified in the test control notation TTCN-3 and compiled to run the validation tests. © 2012 IIMC Ltd.
Palaghias N, Hoseinitabatabaei SA, Nati M, Gluhak A, Moessner K (2015) Accurate Detection of Real-world Social Interactions with Smartphones, 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC) pp. 579-585 IEEE
Li N, Moessner K (2007) The MVCE knowledge-based content and service adaptation management framework, 7th International Workshop on Applications and Services in Wireless Networks, ASWN 2007
The range of content and services on the Internet, the diversity of terminals and the heterogeneity of network technologies to access these services make it a necessity to implement some means to adapt both content and services to meet the needs of the communication environment of the service consumer. An adaptation management framework to support content/service adaptation will take away the complexity of the delivery of compound services from the user and content/service provider. This paper introduces such a context-aware content/service adaptation management framework which uses knowledge-based semantic Web and Web service technologies to facilitate the interoperability between the different technologies and domains involved in content/service adaptation, e.g. the user's context, the content/service and the available adaptation tools. This work, being part of Mobile VCE (MVCE) Ubiquitous Services project, advances the knowledge-based approaches by, firstly, proposing a distributed architecture for such a framework to accelerate its real-world deployment, and secondly, providing mechanisms for adaptation decision making and adaptation tools selection. This paper provides an overview of the framework architecture and outlines the functionalities of its constituent components, i.e. Adaptation Manager and Content Adaptor, as well as the communication mechanisms applied.
Ta-Shma P, Akbar A, Gerson-Golan G, Hadash G, Carrez F, Moessner K (2017) An Ingestion and Analytics Architecture for IoT applied to Smart City Use Cases, IEEE Internet of Things 5 (2) pp. 765-774 Institute of Electrical and Electronics Engineers (IEEE)
As sensors are adopted in almost all fields of life,
the Internet of Things (IoT) is triggering a massive influx of data.
We need efficient and scalable methods to process this data to
gain valuable insight and take timely action. Existing approaches
which support both batch processing (suitable for analysis of
large historical data sets) and event processing (suitable for realtime
analysis) are complex. We propose the hut architecture,
a simple but scalable architecture for ingesting and analyzing
IoT data, which uses historical data analysis to provide context
for real-time analysis. We implement our architecture using
open source components optimized for big data applications and
extend them where needed. We demonstrate our solution on two
real-world smart
Chen Y, De S, Kernchen R, Moessner K (2012) Device discovery in future service platforms through SIP, pp. 1-5
This paper proposes an extension to Session Initiation Protocol (SIP) for contextualized service delivery in a service delivery platform (SDP) that enables device specific multimedia delivery. SIP separates between session establishment and description and is thus, amenable to be extended for advanced implementations which make it an ideal platform for service creation. Device specific multimedia delivery needs rich and flexible device descriptions, and our approach proposes advanced device descriptions through semantic technologies. The proposed SIP extensions have been implemented on a SIP Application Server which functions as SDP in IP Multimedia Subsystem (IMS). The validation of the proposed extensions is shown through an Android SIP client application that acts as a device browser and recommender for different multimedia services to users. An example device user agent (UA) application has also been implemented on a laptop.
Huang L, Chew K, Thilakawardana S, Liu Y, Moessner K, Tafazolli R (2006) Efficient group-based multimedia-on-demand service delivery in wireless networks, IEEE TRANSACTIONS ON BROADCASTING 52 (4) pp. 492-504 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Recently, an upsurge of interest has been observed in providing multimedia on-demand (MoD) services to mobile users over wireless networks. Nevertheless, due to the rapidly varying nature of mobile networks and the scarcity of radio resources, the commercial implementation is still limited. This paper presents an efficient group-based multimedia-on-demand (GMoD) service model over multicast-enabled wireless infrastructures, where users requesting the same content are grouped and served simultaneously with a single multicast stream. The grouping is fulfilled through a process named "batching". An analytical model is derived to analyse a timeout-based hatching scheme with respect to the tradeoff between user blocking probability and reneging probability. Based on the deduced analytical model, an optimal timeout-based hatching scheme is proposed to dynamically identify the optimal tradeoff point that maximizes the system satisfaction ratio given a particular system status. The proposed scheme is evaluated by means of simulation and compared with two basic hatching schemes (timeout-based, size-based), and two hybrid ones (combined-for-profit, combined-for-loss). The simulation results demonstrate the proposed approach can ensure significant gains in terms of user satisfaction ratio, with low reneging and blocking probabilities.

Jin J, Palaniswami M, Yuan D, Dong Y, Moessner K (2016) Priority Service Provisioning and Max-Min Fairness: A Utility-based Flow Control Approach, Journal of Network and Systems Management 25 (2) pp. 397-415 Springer
In this paper, a novel priority assignment scheme is proposed for priority service networks, in which each link sets its own priority threshold, namely, the lowest priority the link is willing to support for the incoming packets without causing any congestion. Aiming at a reliable transmission, the source then assigns each originated packet the maximum priority value required along its path, because links may otherwise discard the incoming packets which do not meet the corresponding priority requirements. It is shown that if each source sends the traffic at a rate that is reciprocal to the specified highest priority, a bandwidth max-min fairness is achieved in the network. Furthermore, if each source possesses a utility function of the available bandwidth and sends the traffic at a rate so that the associated utility is reciprocal to the highest link priority, a utility max-min fairness is achieved. For general networks without priority services, the resulting flow control strategy can be treated as a unified framework to achieve either bandwidth max-min fairness or utility max-min fairness through link pricing policy. More importantly, the utility function herein is only assumed to be strictly increasing and does not need to satisfy the strictly concave condition, the new algorithms are thus not only suitable for the traditional data applications with elastic traffic, but are also capable of handling real-time applications in the Future Internet.
Bouali F, Moessner K, Fitch M (2017) A Context-aware User-driven Strategy to Exploit Offloading and Sharing in Ultra-dense Deployments, 2017 IEEE ICC Conference Proceedings IEEE
This paper proposes a novel context-aware userdriven
strategy to efficiently exploit all available bands and
licensing regimes in ultra-dense deployments without prior
knowledge about each combination. It relies first on fuzzy logic
to estimate the suitability of each radio access technology (RAT)
to support the requirements of various applications. Then, a
fuzzy multiple attribute decision making (MADM) approach is
developed to combine these estimates with the heterogeneous
context components to assess the in-context suitability. Based
on this metric, a spectrum management strategy is proposed to
support interactive video sessions for a set of Bronze and Gold
subscriptions. The results reveal that the proposed approach
always assigns Gold users to the well-regulated licensed band,
while switches Bronze users between licensed and unlicensed
bands depending on the operating conditions. This results in
a significant improvement of the quality-of-experience (QoE)
compared to a baseline that exploits only licensed bands. Then,
a comparative study is conducted between the available options
to exploit unlicensed bands, namely Offloading and Sharing. The
results show that the best option strongly depends on the existing
load on WLAN. Therefore, a combined approach is proposed to
efficiently switch between both options, which achieves the best
QoE for all considered loads.
Lee H, Vahid S, Moessner K (2017) Traffic-aware Carrier Allocation with Aggregation for Load Balancing, EuCNC 2017 Conference Proceedings
We consider the resource allocation with aggregation of multiple bands including unlicensed band for heterogeneous traffic. While the mobile data traffic including high volume of video traffic is expected to increase significantly, an efficient management of radio resources from multiple bands is required to guarantee the quality of service (QoS) of different traffic types. In this context, we formulate an optimal resource allocation by using different utility functions for heterogeneous traffic and the two-step resource allocation algorithm including resource grouping has been proposed. Simulation results demonstrate that the proposed algorithm enhances the connection robustness and shows good performance in terms of higher utility value of inelastic traffic even at high traffic loads by steering elastic traffic to unlicensed band.
Gluhak A, Chew K, Moessner K, Tafazolli R (2005) Multicast bearer selection in heterogeneous wireless networks, Proc. IEEE Int. Conf. Communications ICC 2005 2 pp. 1372-1377
Network scenarios beyond 3G assume the cooperation of operators with wireless access networks of different technologies in order to improve scalability and provide enhanced services to their mobile customers. While the selection of an optimised delivery path in such scenarios with multiple access networks is already a challenging task for unicast delivery, the problem becomes more severe for multicast services, where a potentially large group of heterogeneous receivers has to be served simultaneously via shared resources. In this paper we study the problem of selecting the optimal bearer paths for multicast services with groups of heterogeneous receivers in wireless networks with overlapping coverage. We propose an algorithm for bearer selection with different optimisation goals, demonstrating the existing tradeoff between user preference and resource efficiency.
Francois F, Wang N, Moessner K, Georgoulas S (2012) Optimizing Link Sleeping Reconfigurations in ISP Networks with Off-Peak Time Failure Protection, IEEE Transactions on Network and Service Management 10 (2) pp. 176-188 IEEE
Energy consumption in ISP backbone networks has been rapidly increasing with the advent of increasingly bandwidth-hungry applications. Network resource optimization through sleeping reconfiguration and rate adaptation has been proposed for reducing energy consumption when the traffic demands are at their low levels. It has been observed that many operational backbone networks exhibit regular diurnal traffic patterns, which offers the opportunity to apply simple time-driven link sleeping reconfigurations for energy-saving purposes. In this work, an efficient optimization scheme called Time-driven Link Sleeping (TLS) is proposed for practical energy management which produces an optimized combination of the reduced network topology and its unified off-peak configuration duration in daily operations. Such a scheme significantly eases the operational complexity at the ISP side for energy saving, but without resorting to complicated online network adaptations. The GÉANT network and its real traffic matrices were used to evaluate the proposed TLS scheme. Simulation results show that up to 28.3% energy savings can be achieved during off-peak operation without network performance deterioration. In addition, considering the potential risk of traffic congestion caused by unexpected network failures based on the reduced topology during off-peak time, we further propose a robust TLS scheme with Single Link Failure Protection (TLS-SLFP) which aims to achieve an optimized trade-off between network robustness and energy efficiency performance.
Guo T, Wang N, Tafazolli R, Moessner K (2010) Policy-Aware Virtual Relay Placement for Inter-Domain Path Diversity, IEEE ISCC pp. 38-43
Exploiting path diversity to enhance communication
reliability is a key desired property in Internet. While the existing routing architecture is reluctant to adopt changes, overlay routing has been proposed to circumvent the constraints of native routing by employing intermediary relays. However, the selfish interdomain relay placement may violate local routing policies at intermediary relays and thus affect their economic costs and performances. With the recent advance of the concept of network virtualization, it is envisioned that virtual networks should be provisioned in cooperation with infrastructure providers in a holistic view without compromising their profits. In this paper, the problem of policy-aware virtual relay placement is first studied to investigate the feasibility of provisioning policycompliant multipath routing via virtual relays for inter-domain communication reliability. By evaluation on a real domain-level Internet topology, it is demonstrated that policy-compliant virtual
relaying can achieve a similar protection gain against single link failures compared to its selfish counterpart. It is also shown that the presented heuristic placement strategies perform well to approach the optimal solution.
Wang W, De S, Zhou Y, Huang X, Moessner K (2017) Distributed Sensor Data Computing in Smart City
Applications,
Proceedings of WoWMoM 2017
With technologies developed in the Internet of
Things, embedded devices can be built into every fabric of urban
environments and connected to each other; and data continuously
produced by these devices can be processed, integrated at different
levels, and made available in standard formats through open
services. The data, obviously f a form of ?big data?, is now seen as
the most valuable asset in developing intelligent applications. As
the sizes of the IoT data continue to grow, it becomes inefficient
to transfer all the raw data to a centralised, cloud-based data
centre and to perform efficient analytics even with the state-ofthe-
art big data processing technologies. To address the problem,
this article demonstrates the idea of ?distributed intelligence? for
sensor data computing, which disperses intelligent computation
to the much smaller while autonomous units, e.g., sensor network
gateways, smart phones or edge clouds in order to reduce
data sizes and to provide high quality data for data centres.
As these autonomous units are usually in close proximity to
data consumers, they also provide potential for reduced latency
and improved quality of services. We present our research on
designing methods and apparatus for distributed computing on
sensor data, e.g., acquisition, discovery, and estimation, and
provide a case study on urban air pollution monitoring and
visualisation.
Understanding human behaviour in an automatic but also non-intrusive manner, constitutes an important and emerging area for various fields. This requires collaboration of information technology with humanitarian sciences in order to transfer existing knowl- edge of human behaviour into self-acting tools to eliminate the human error. This work strives to shed some light in the area of Mobile Social Signal Processing by trying to understand if today?s mobile devices, given their advanced sensing and computational capabilities, are able to extract various aspects of human behaviour. Although one of the core aspects of human behaviour are social interactions, current tools do not pro- vide an accurate, reliable and real-time solution for social interaction detection, which constitutes a significant barrier in automatic human behaviour understanding.
Towards filling the aforementioned gap in order to enable human behaviour under- standing through mobile devices, particular contributions were made. Firstly, an interpersonal distance estimation technique is developed based upon a non-intrusive opportunistic mechanism that solely relies on sensors and communication capabilities of off-the-shelf smartphones. Secondly, based on user?s interpersonal distance and relative orientation, a pervasive and opportunistic approach based on off-the-shelf smartphones for social interaction detection system is presented. Leveraging information provided by psychology, analytical and error models are proposed to estimate the probability of people having social interactions. Then, to showcase the ability of mobile devices to infer human behaviour, a trust relationship quantification mechanism is developed based on users? behavioural traits and psychological models. Finally, a prediction and compensation mechanism for the device displacement error that leverages human loco- motion patterns to refine the device orientation is introduced.
The above contributions were evaluated through experimentation and hard data collected from real-world environments to prove their accuracy and reliability as well as showing the applicability of the proposed approaches in daily situations. This work showed that mobile devices are able to accurately detect social interactions and further social and trust relationships among people, despite the noise induced in real-world situations. Close collaboration between informatics and social sciences is imperative, to overcome the significant barrier in the d
Wang W, Yao F, De S, Moessner K, Sun Z (2015) A Ranking Method for Sensor Services based on Estimation of Service Access Cost, Information Sciences 319 pp. 1-17 Elsevier
The concept of sensing-as-a-service is proposed to enable a unified way of accessing and controlling sensing devices for many Internet of Things based applications. Existing techniques for Web service computing are not sufficient for this class of services that are exposed by resource-constrained devices. The vast number of distributed and redundantly deployed sensors necessitate specialised techniques for their discovery and ranking. Current research in this line mostly focuses on discovery, e.g., designing efficient searching methods by exploiting the geographical properties of sensing devices. The problem of ranking, which aims to prioritise semantically equivalent sensor services returned by the discovery process, has not been adequately studied. Existing methods mostly leverage the information directly associated with sensor services, such as detailed service descriptions or quality of service information. However, assuming the availability of such information for sensor services is often unrealistic. We propose a ranking strategy by estimating the cost of accessing sensor services. The computation is based on properties of the sensor nodes as well as the relevant contextual information extracted from the service access process. The evaluation results demonstrate not only the superior performance of the proposed method in terms of ranking quality measure, but also the potential for preserving the energy of the sensor nodes.
De S, Zhou Y, Abad I, Moessner K (2017) Cyber?Physical?Social Frameworks for Urban Big Data Systems: A Survey, MDPI Applied Sciences 7 (10) 101017 MDPI AG
The integration of things? data on the Web and Web linking for things? description and discovery is leading the way towards smart Cyber?Physical Systems (CPS). The data generated in CPS represents observations gathered by sensor devices about the ambient environment that can be manipulated by computational processes of the cyber world. Alongside this, the growing use of social networks offers near real-time citizen sensing capabilities as a complementary information source. The resulting Cyber?Physical?Social System (CPSS) can help to understand the real world and provide proactive services to users. The nature of CPSS data brings new requirements and challenges to different stages of data manipulation, including identification of data sources, processing and fusion of different types and scales of data. To gain an understanding of the existing methods and techniques which can be useful for a data-oriented CPSS implementation, this paper presents a survey of the existing research and commercial solutions. We define a conceptual framework for a data-oriented CPSS and detail the various solutions for building human?machine intelligence.
The increasing demand for context awareness makes WS&ANs (Wireless Sensor and Actuator Network) a rather popular topic. In recent years, a wide range of commercial applications based on WS&ANs have been released, such as smart home solutions, Smart City solutions, e-Healthcare. In these applications, a large number of different sensor network protocols are applied to fulfil various functionalities and purposes of WS&ANs. Additionally, heterogeneous sensor nodes from multi-vendor are deployed.
Although the importance of interconnection between heterogeneous sensor platforms is commonly acknowledged in order to provide better quality and more quantity of the services, it is still a big challenge due to the heterogeneity such as specific administrative control, various protocols, different purpose and the economic interests of WS&ANs vendors.
With the focus on the network level, this research aims to provide a solution for realising interconnection between heterogeneous sensor platforms and WS&ANs, which enables the possibility of sharing and utilising resources across sensor nodes and networks without the obstacle brought by their heterogeneity. Instead of following the main research direction, network virtualisation, to design and standardize a one-fits-all protocol and middleware that should cater for the requirements of the different types of WS&ANs, a new approach called Progressive Protocol Stack Reconfiguration (PPSR) is proposed. With the reconfigurability of protocol stacks, this approach enables communication management between heterogeneous networks by adapting the protocol stacks to one another at lower cost and delay.
PPSR was simulated and implemented in this research to prove the success of the concept. Being applied in gateways between the sensor networks and the access networks, the PPSR approach increases the flexibility and facilitates connectivity for networks when a sensor network roams between heterogeneous networks.
Bouali F, Moessner K, Fitch M (2017) A Context-aware QoE-driven Strategy for Adaptive Video Streaming in 5G multi-RAT Environments, Proceedings of the 20th International Symposium on Wireless Personal Multimedia Communications (WPMC 17)
This paper extends traditional dynamic adaptive
streaming over HTTP (DASH) to efficiently exploit all available
bands and licensing regimes in a given context. A novel objective
quality-of-experience (QoE) metric is proposed to capture
the most relevant factors that impact user perception during
streaming sessions. Based on it, a QoE-driven adaptation strategy
is devised to jointly select the best radio access technology
(RAT) and quality for each video segment depending on the
various components of the context. It relies first on fuzzy
logic to estimate the QoE provided by each available RAT
subject to the uncertainty level associated with DASH clients.
Then, a fuzzy multiple attribute decision making (MADM)
methodology is developed to combine the QoE estimates with the
heterogeneous components of the context to assess the in-context
suitability levels. The proposed approach is applied to adapt
video streaming across available RATs in dense deployments for
a set of Bronze and Gold subscriptions. The results reveal that
the proposed strategy always assigns Gold clients to the wellregulated
licensed band, while switches Bronze clients between
licensed and unlicensed bands depending on the operating
conditions. It strikes a balance between maximising video quality
and reducing playback stalling, which significantly improves the
perceived QoE compared to the traditional DASH approach.
Jiang J, Pozza R, Gunnarsdottir K, Gilbert G, Moessner K (2017) Using Sensors to Study Home Activities, Journal of Sensor and Actuator Networks 6 (4) MDPI
Understanding home activities is important in social research to study aspects of home life, e.g., energy-related practices and assisted living arrangements. Common approaches to identifying which activities are being carried out in the home rely on self-reporting, either retrospectively (e.g., interviews, questionnaires, and surveys) or at the time of the activity (e.g., time use diaries). The use of digital sensors may provide an alternative means of observing activities in the home. For example, temperature, humidity and light sensors can report on the physical environment where activities occur, while energy monitors can report information on the electrical devices that are used to assist the activities. One may then be able to infer from the sensor data which activities are taking place. However, it is first necessary to calibrate the sensor data by matching it to activities identified from self-reports. The calibration involves identifying the features in the sensor data that correlate best with the self-reported activities. This in turn requires a good measure of the agreement between the activities detected from sensor-generated data and those recorded in self-reported data. To illustrate how this can be done, we conducted a trial in three single-occupancy households from which we collected data from a suite of sensors and from time use diaries completed by the occupants. For sensor-based activity recognition, we demonstrate the application of Hidden Markov Models with features extracted from mean-shift clustering and change points analysis. A correlation-based feature selection is also applied to reduce the computational cost. A method based on Levenshtein distance for measuring the agreement between the activities detected in the sensor data and that reported by the participants is demonstrated. We then discuss how the features derived from sensor data can be used in activity recognition and how they relate to activities recorded in time use diaries.
Bermudez-Edo M, Barnaghi P, Moessner K (2018) Analysing real world data streams with spatio-temporal correlations: Entropy vs. Pearson correlation, Automation in Construction 88 pp. 87-100 Elsevier
Smart Cities use different Internet of Things (IoT) data sources and rely on big data analytics to obtain information or extract actionable knowledge crucial for urban planners for efficiently use and plan the construction infrastructures. Big data analytics algorithms often consider the correlation of different patterns and various data types. However, the use of different techniques to measure the correlation with smart cities data and the exploitation of correlations to infer new knowledge are still open questions. This paper proposes a methodology to analyse data streams, based on spatio-temporal correlations using different correlation algorithms and provides a discussion on co-occurrence vs. causation. The proposed method is evaluated using traffic data collected from the road sensors in the city of Aarhus in Denmark.
Akbar A, Kousiouris G, Pervaiz H, Sancho J, Ta-Shma P, Carrez F, Moessner K (2018) Real-time Probabilistic Data Fusion for Large-scale IoT Applications, IEEE Access 6 pp. 10015-10027 Institute of Electrical and Electronics Engineers (IEEE)
IoT data analytics is underpinning numerous applications,
however the task is still challenging predominantly due
to heterogeneous IoT data streams, unreliable networks and ever
increasing size of the data. In this context, we propose a two layer
architecture for analyzing IoT data. The first layer provides a
generic interface using a service oriented gateway to ingest data
from multiple interfaces and IoT systems, store it in a scalable
manner and analyze it in real-time to extract high-level events
whereas second layer is responsible for probabilistic fusion of
these high-level events. In the second layer, we extend state-ofthe-
art event processing using Bayesian networks (BNs) in order
to take uncertainty into account while detecting complex events.
We implement our proposed solution using open source components
optimized for large-scale applications. We demonstrate
our solution on real-world use-case in the domain of intelligent
transportation system (ITS) where we analysed traffic, weather
and social media data streams from Madrid city in order to
predict probability of congestion in real-time. The performance
of the system is evaluated qualitatively using a web-interface
where traffic administrators can provide the feedback about the
quality of predictions and quantitatively using F-measure with
an accuracy of over 80%.
Mikusz M, Houben S, Davies N, Moessner K, Langheinrich M (2018) Raising Awareness of IoT Sensor Deployments, Proceedings of Living in the Internet of Things: Cybersecurity of the IoT Institute of Engineering and Technology
The IoT is increasingly being used to support smart spaces and
physical analytics and yet much of this smartness is made deliberately
invisible to the user?echoingWeiser?s vision of calm
computing and technology that fades into the background.
However, this means that users may not be aware or may not
understand how the IoT is being deployed in their area. In
other domains we know that a lack of awareness and a lack
of understanding can lead to poor user experience/frustration,
mistrust, suspicion, inability to capitalise on benefits and, security
vulnerabilities. In this paper we present preliminary work
that explores the issue of user awareness of IoT-based data collection.
Bouali F, Moessner K, Fitch M (2018) Spectrum Utility: a Novel Metric for Efficient Spectrum Usage in Next-generation Networks, VTC 2018 Conference Proceedings IEEE
This paper proposes a novel spectrum utility (SU)
metric that assesses the efficiency of spectrum usage by a set
of heterogeneous applications. Unlike the traditional spectrum
efficiency (SE), the proposed metric does not blindly consider the
achievable bit-rate, but captures the most relevant performance
metrics for each of the considered applications. Specifically, it is
formulated as an aggregated utility that combines the satisfaction
level with respect to the various requirements with an innovative
pricing model based on it to derive the total revenue generated
for the spectrum owner. To get insight into the usefulness of the
proposed metric, the proposed methodology is instantiated for
an illustrative use case, where a mixture of delay-sensitive (i.e.,
interactive video) and -tolerant (i.e., file transfer) applications are
established in dense indoor deployments. The obtained results
reveal that the proposed SU significantly outperforms the legacy
SE in assessing how efficiently a limited frequency spectrum is
utilised from the perspective of the total revenue, particularly
when the quality-of-experience (QoE) perceived during video
sessions is degraded. This calls for a novel SU-aware ecosystem,
where the spectrum sharing models, billing policies and resource
allocation mechanisms (e.g., medium access control (MAC) and
radio resource management (RRM)) are jointly revisited to
maximise the overall SU.
Investigation of the state-of-the-art in Cyber-Physical-Social System (CPSS) reveals that significant work has been done in interpreting data from different sources in isolation, performing correlations for numerical observations across one or two domains, or to provide simple textual explanations from social networks content for analysed physical world data. Existing works also work with ideal sets or already cleaned data that does not provide the same real-world insight into working with big data in cities. Thus, there is a need for integrated solutions that address the complete data flow; from data acquisition to processing and knowledge representation.
This thesis presents a data-centric framework for CPSS that contains management and processing capabilities for knowledge discovery from mobile sensing data and social networks content, by mainly addressing challenges from mobile sensing scenarios in CPSS, including: 1) interoperability issues caused by the vast amount of heterogeneous data sources; 2) thematic-spatial-temporal information retrieval of opportunistic mobile sensing; 3) incomplete datasets generated from noisy data sources of mobile sensing techniques; 4) different scales/types of data and information, which cannot be correlated directly.
The contributions of the thesis include 1) a data retrieval method that addresses the issue of searching for both current and historical sensor measurement values from the heterogeneous data sources; 2) a novel spatio-temporal model for regression analysis that can perform missing data estimation in the incomplete datasets; 3) a knowledge discovery mechanism that merges and correlates physical and social sensing data, enabling links between different scales/types of data: numeric values of sensor observation data and textual content of social networks? messages.
The above contributions were evaluated through experimentation on real smart city datasets and data collected from the Twitter social network to prove their accuracy and reliability, as well as to show the applicability of the proposed approaches to existing smart cities.
Lee H, Vahid S, Moessner K (2018) Traffic-aware Resource allocation with aggregation in Heterogeneous Networks with WLANs, Proceedings of the 27th European Conference on Networks and Communications 2018 (EUCNC 2018) Institute of Electrical and Electronics Engineers (IEEE)
We consider resource allocation with aggregation for
different types of traffic in heterogeneous networks, including
WLANs. While mobile data traffic is expected to increase, efficient
management of multiple bands including unlicensed band
becomes increasingly important. In this context, we formulate a
resource allocation problem using utility functions for heterogeneous
traffic and propose a novel algorithm that considers the
estimated UE speed, traffic types and channel quality. Simulation
results illustrate performance of the proposed algorithm in
terms of higher utility value and fairness, even at high traffic
loads. Additional improvements in resource utilization through
estimating UE speed and allocating low-mobility UEs to Wi-Fi
are shown.
Lee H, Ko Y, Vahid S, Moessner K (2015) Practical Spectrum Aggregation for Secondary Networks with Imperfect Sensing, IEEE Transactions on Vehicular Technology 65 (7) pp. 5474-5484 Institute of Electrical and Electronics Engineers (IEEE)
We investigate a collision-sensitive secondary network that intends to opportunistically aggregate and utilize spectrum of a primary network to achieve higher data rates. In opportunistic spectrum access with imperfect sensing of idle primary spectrum, secondary transmission can collide with primary transmission. When the secondary network aggregates more channels in the presence of the imperfect sensing, collisions could occur more often, limiting the performance obtained by spectrum aggregation. In this context, we aim to address a fundamental query, that is, how much spectrum aggregation is worthy with imperfect sensing. For collision occurrence, we focus on two different types of collision: one is imposed by asynchronous transmission; and the other by imperfect spectrum sensing. The collision probability expression has been derived in closed-form with various secondary network parameters: primary traffic load, secondary user transmission parameters, spectrum sensing errors, and the number of aggregated sub-channels. In addition, the impact of spectrum aggregation on data rate is analysed under the constraint of collision probability. Then, we solve an optimal spectrum aggregation problem and propose the dynamic spectrum aggregation approach to increase the data rate subject to practical collision constraints. Our simulation results show clearly that the proposed approach outperforms the benchmark that passively aggregates sub-channels with lack of collision awareness.
Li J, Jin J, Yuan D, Palaniswami M, Moessner K (2017) A Data-centered Fog
Platform for Smart Living,
In: Sun H, Wang C, Ahmad B (eds.), From Internet of Things to Smart Cities: Enabling Technologies pp. 357-377 CRC Press, Taylor & Francis Group
Nowadays, smart environments (e.g., smart home, smart city) are built heavily
relying on Cloud computing for the coordination and collaboration among
smart objects. The Cloud is typically centralized but smart objects are ubiquitously
distributed; thus, data transmission latency (i.e., end-to-end delay or response time)
between Cloud and smart objects is a critical issue especially to the applications
that have strict delay requirements. To address this concern, a new Fog computing
paradigm has been recently proposed by the industry. The key idea is to bring the
computing power from the remote Cloud closer to the users, which further enables
real-time interaction and location-based services. In particular, the local processing
capability of Fog computing significantly scales down the data volume towards
the Cloud, and it in turn has great impacts on the entire Internet. In this chapter,
smart living as one of the primary elements of smart cities has been conceptualized
to EHOPES, namely smart Energy, smart Health, smart Office, smart Protection,
smart Entertainment and smart Surroundings. And then the data flow analysis has
been investigated to disclose a variety of data flow characteristics. Based on these
studies, a data-centered Fog platform has been developed to support smart living.
Case studies are also conducted to validate and evaluate the proposed platform.
So far, the Internet of Things (IoT) has been concerned with the objective of connecting every-thing, or any object to the Internet world. By collaborating towards the creation of new services, the IoT has introduced the opportunity to add smartness to our cities, homes, buildings and healthcare systems, as well as businesses and products. In many scenarios, objects or IoT devices are not always statically deployed, but they may be free to move around being carried by people or vehicles, while still interacting with static IoT infrastructure. The Opportunistic Networking paradigm states that, exploiting opportunistic interactions between static and mobile IoT devices, provides for increased network capacity, additional connectivity, reduced deployment costs, improved reliability and overall network lifetime improvements.

IoT scenarios do illustrate the increased need to identify and exploit opportunistic interactions between IoT devices in order to recognize when an opportunity for communication is possible. For example, statically deployed devices (i.e. road side sensors) may need to find mobile devices (this may be sensors or actuators) (i.e. connected cars) for exploiting them for collecting and relaying data towards destinations without relying on a static infrastructure. This means that discovery in IoT scenarios needs to determine the availability of other devices in scenarios in which devices' presence is uncertain or may change over time. This directly leads to a contradicting objective where resource wastage in device discovery is to be kept at a minimum.

This thesis presents two contributions that provide solutions to overcome the clash between these contradicting objectives. Firstly, a Context Aware Resource Discovery mechanism is introduced, capable of providing optimized discovery and adapting available resources based on learned mobility patterns. Secondly, an Arrival and Departure Time Prediction and Discovery framework is defined and investigated; this framework aims to predict future arrival and departure times and helps to plan the use of devices' resources in advance based on the foreseen resource demand patterns.

Cassar G, Barnaghi P, Wang W, De S, Moessner K (2013) Composition of Services in Pervasive Environments: A Divide and Conquer Approach, IEEE Symposium on Computers and Communications
In pervasive environments, availability and reliability of a service cannot always be guaranteed. In such environments, automatic and dynamic mechanisms are required to compose services or compensate for a service that becomes unavailable during the runtime. Most of the existing works on services composition do not provide sufficient support for automatic service provisioning in pervasive environments. We propose a Divide and Conquer algorithm that can be used at the service runtime to repeatedly divide a service composition request into several simpler sub-requests. The algorithm repeats until for each sub-request we find at least one atomic service that meets the requirements of that sub-request. The identified atomic services can then be used to create a composite service. We discuss the technical details of our approach and show evaluation results based on a set of composite service requests. The results show that our proposed method performs effectively in decomposing a composite service requests to a number of sub-requests and finding and matching service components that can fulfill the service composition request.
Triantafyllopoulou Dionysia, Vahid Seiamak, Moessner Klaus (2018) Co-Primary Spectrum Sharing in Uplink
SC-FDMA Networks,
IEEE PIMRC 2018 Proceedings IEEE
In this paper we present a co-primary spectrum
sharing algorithm for the Quality of Service (QoS)
enhancement of uplink Single-Carrier Frequency Division
Multiple Access (SC-FDMA) systems. We consider the
limitations that are resulting from the fact that each
user can only be provided with only contiguous sets of
resource blocks (following the constraints of the localized
SC-FDMA physical layer), and the effect of the limited, or
even lack of, knowledge of each user?s buffer status and
packet delays in the uplink. The sharing of available resources
is based on the operator spectrum access priority,
an estimation of the packet delays in the uplink direction,
the average delay and data rate of earlier allocations, and
the power per resource block. Simulation results show
that the proposed algorithm considerably improves the
performance in terms of packet loss rate, goodput, and
fairness.