Connected autonomous vehicles are considered as mitigators
of issues such as traffic congestion, road safety, inefficient fuel
consumption and pollutant emissions that current road transportation
system suffers from. Connected autonomous vehicles
utilise communication systems to enhance the performance of
autonomous vehicles and consequently improve transportation by
enabling cooperative functionalities, namely, cooperative sensing
and cooperative manoeuvring. The former refers to the ability to
share and fuse information gathered from vehicle sensors and road
infrastructures to create a better understanding of the surrounding
environment while the latter enables groups of vehicles to drive in
a co-ordinated way which ultimately results in a safer and more efficient
driving environment. However, there is a gap in understanding
howand to what extent connectivity can contribute to improving the
efficiency, safety and performance of autonomous vehicles. Therefore,
the aim of this paper is to investigate the potential benefits
that can be achieved from connected autonomous vehicles through
analysing five use-cases: (i) vehicle platooning, (ii) lane changing,
(iii) intersection management, (iv) energy management and (v) road
friction estimation. The current paper highlights that although connectivity
can enhance the performance of autonomous vehicles and
contribute to the improvement of current transportation system performance,
the level of achievable benefits depends on factors such
as the penetration rate of connected vehicles, traffic scenarios and
the way of augmenting off-board information into vehicle control
Environmental problems, such as pollution, become more serious year after year. One of the major causes is high fossil fuel consumption with CO2 emission. In 2009, 23 percent of CO emission globally came from land transportation systems, which is equal to 7000 million tons of CO. This large amount of gas pollution should be reduced to slow down global environmental problems. Reduction of fuel consumption and CO emission in land transportation systems, which will have immediate positive economical and environmental impact, has become an important part of green technologies to alleviate global warming due to human activity. Intelligent transportation systems, which aim to use information and communication technology in the transportation systems, are considered to be a major enabler for the future green ITS. This article aims to provide a survey of the latest published applications based on vehicular communications as well as the envisaged technical challenges in this research area. © 2012 IEEE.
In this paper, we propose two analytical models for per-user throughput of an opportunistic scheduling scheme over a broadcast fading channel. For the first model, we use a piecewise linear approximation of the achievable transmission rates versus the values of Signal to Noise and Interference Ratio (SINR). We obtain the conditional average transmission rate of a mobile station, given the maximum channel quality of the other competing mobile stations. Using the probability distribution function of the maximum channel quality of the competing mobile stations, we obtain a closed form unconditional average transmission rate, i.e., per-user throughput, of a mobile station. For the second model, we use a similar approach, but with a precise model of the achievable rates. Furthermore, statistically nonidentical channels for different mobile stations are considered. Thus, the second model is more general and provides more accurate solution, but it requires more computations. The proposed models are useful for call admission control as well as performance studies of wireless networks. Simulation results are given to demonstrate the accuracy of the proposed analytical models. © 2006 IEEE.
Dianati M, Shen XS, Naik K (2007) Scheduling with base station diversity and fairness analysis for the downlink of CDMA cellular networks, WIRELESS COMMUNICATIONS & MOBILE COMPUTING7(5)pp. 569-579 JOHN WILEY & SONS INC
In this paper, we propose a ¯nite-state Markov model for per-user service of an oppor-
tunistic scheduling scheme over Rayleigh fading channels, where a single base station serves
an arbitrary number of users. By approximating the power gain of Rayleigh fading chan-
nels as ¯nite-state Markov processes, we develop an algorithm to obtain dynamic stochastic
model of the transmission service, received by an individual user for a saturated scenario,
where user data queues are highly loaded. The proposed analytical model is a ¯nite-state
Markov process. We provide a comprehensive comparison between the predicted results by
the proposed analytical model and the simulation results, which demonstrate a high degree
of match between the two sets.
This paper investigates energy efficiency (EE) performance of a virtual multiple-input multiple-output (MIMO) wireless system using the receiver-side cooperation with the compress-and-forward protocol. We derive a linear approximation of EE as a function of spectral efficiency (SE) in the low SE operation regime. In addition, we obtain a closed-form lower bound for EE which is valid for both low and high SE regions. This lower bound can be used for optimizing the power allocation between the transmitter and the relay in order to minimize the overall energy per bit consumption in the system. Both analytical and simulation results demonstrate that the virtual MIMO system using the receiver-side cooperation outperforms the multiple-input single-output (MISO) case in terms of energy efficiency. Finally we show that, with the optimal power allocation, the virtual-MIMO system achieves an EE performance close to that of an ideal MIMO system.
Dianati M, (Sherman) Shen X, Naik K (2007) Cooperative fair scheduling for the downlink of CDMA cellular networks, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY56(4)pp. 1749-1760 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Sabagh MR, Dianati M, Imran MA, Tafazolli R (2013) A heuristic energy efficient scheduling scheme for VoIP in 3GPP LTE networks, 2013 IEEE International Conference on Communications Workshops, ICC 2013pp. 413-418
In this paper, first, energy efficiency of well known and principal scheduling schemes, Round Robin (RR), Best Channel Quality Indicator (BCQI), and Proportional Fair (PF) is evaluated. Then, a novel energy efficient scheme in low load traffic conditions is proposed. The proposed scheme trades off bandwidth for energy whenever possible depending on the load of the network. By applying this approach on the principal schedulers, three relevant energy efficient schedulers for Voice over IP (VoIP) traffic, namely, Energy Efficient Round Robin (EERR), Energy Efficient Best Channel Quality Indicator (EE-BCQI), and Energy Efficient Proportional Fair (EEPF) are introduced. The results of performance analysis, which are based on the specifications of the downlink of 3GPP LTE (Long Term Evolution) demonstrate the superior performance of the proposed scheme in terms of energy consumption of the network, while providing required Quality of Service (QoS) for the users. © 2013 IEEE.
Mehrjoo M, Awad MK, Dianati M, Shen X (2009) Maintaining utility fairness using weighting factors in wireless networks, GLOBECOM - IEEE Global Telecommunications Conference
Psaras I, Dianati M, Tafazolli R (2009) Why rely on blind AIMDs? (work in progress),Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)5550 LNCSpp. 404-415
We are motivated by the fact that fixed Increase rates and Decrease ratios for AIMD cannot adjust TCP's performance to the Internet's diverse networking conditions. Indeed, we find that fixed values for the increase/decrease factors of AIMD restrain flexibility, which is a fundamental property of transport protocols in order to guarantee utilization and fairness in Modern and Future internetworks. We propose a new paradigm for hybrid AIMD designs that has the potential to adjust TCP's behavior according to network conditions. The proposed Multi-Rate AIMD (MR-AIMD) increases additively the Additive Increase factor of AIMD in case of positive feedback and decreases multiplicatively (the AI factor) in case of negative feedback and Explicit Congestion Notifications. In other words, MR-AIMD takes into account ECN signals in order to quantify the level of network contention and adjusts its response accordingly. We show that MR-AIMD reduces retransmission effort significantly, when contention is high, becomes aggressive when contention decreases and tolerates against random, transient errors due to fading channels. © IFIP International Federation for Information Processing 2009.
Mi D, Dianati M, Muhaidat S, Chen Y (2014) A Novel Antenna Selection Scheme for Spatially Correlated Massive MIMO Uplinks with Imperfect Channel Estimation,
We propose a new antenna selection scheme for a massive MIMO system with a
single user terminal and a base station with a large number of antennas. We
consider a practical scenario where there is a realistic correlation among the
antennas and imperfect channel estimation at the receiver side. The proposed
scheme exploits the sparsity of the channel matrix for the effective selection
of a limited number of antennas. To this end, we compute a sparse channel
matrix by minimising the mean squared error. This optimisation problem is then
solved by the well-known orthogonal matching pursuit algorithm. Widely used
models for spatial correlation among the antennas and channel estimation errors
are considered in this work. Simulation results demonstrate that when the
impacts of spatial correlation and imperfect channel estimation introduced, the
proposed scheme in the paper can significantly reduce complexity of the
receiver, without degrading the system performance compared to the maximum
Katsaros K, Dianati M, Tafazolli R, Guo X (2016) End-to-End Delay Bound Analysis for Location-Based Routing in Hybrid Vehicular Networks, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY65(9)pp. 7462-7475 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Haider F, Dianati M, Tafazolli R (2011) A simulation based study of Mobile Femtocell assisted LTE networks, IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conferencepp. 2198-2203
This paper investigates the impacts of deploying Mobile Femtocell (MFemtocell) in LET networks. We investigate access delay, capacity, and feedback signalling overhead required for implementation of opportunistic scheduling in LTE cellular networks. We particularly study the impacts of deploying MFemtocells stations on the signalling overhead for opportunistic scheduling. Our system level simulation results indicate that one potential advantage of deploying MFemtocells can contribute to improve spectral efficiency by reducing the amount of feedback signalling. © 2011 IEEE.
This paper investigates and proposes the techniques that reduce the number of required feedback channels for implementation of opportunistic scheduling. It is shown that by implementing effective schemes we can exploit significant multiuser diversity gain using a modest number of feedback channels. Simulation based performance analysis is given to demonstrate effectiveness of the proposed schemes in terms of high spectrum efficiency and low feedback overhead. ©2010 Crown.
Shi Y, Katsaros K, Han C, Dianati M APPARATUS AND METHOD FOR TRANSMITTING COMMUNICATION MESSAGES,
The present invention relates to the field of communication technologies, and in particular, to transmitting communication messages.
Zhu X, Dianati M, Zhu H (2014) Analysis of cooperative and competitive spectrum sharing for heterogeneous networks based on differential dynamics model, International Journal of Communication Systems27(12)pp. 4564-4574
Copyright © 2013 John Wiley & Sons, Ltd.The heterogeneous networks belonging to different service providers form a coalition system for maximizing the profit, where they may either compete or cooperate with each other. In this paper, we introduce the Lokta-Volterra model, a differential dynamics model, to build the competitive and cooperative mechanisms of heterogeneous networks. It considers the natural growth rate of the network itself and competitive and cooperative effects among networks. Then, according to the ordinary differential principle, the stability of the proposed model and its equilibrium points are analyzed. And finally, system performances are evaluated by Vensim that is used for developing, analyzing, and packaging dynamic feedback models. Analysis and simulation results show that the natural growth rate of the network cannot increase its profit, but effective cooperative mechanism among heterogeneous networks can increase the profit of each network.
Dianati M, Tafazolli R, Shen X, Naik K (2009) A markov model for per-user service of opportunistic scheduling, Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009pp. 681-686
Shariat M, Dianati M, Seppänen K, Suihko T, Putkonen J, Frascolla V (2015) Enabling Wireless Backhauling for Next Generation mmWave Networks,
This paper presents some key findings w.r.t. the Radio Resource Management (RRM) in wireless Backhaul (BH) of mmWave networks. First, the envisioned design of mmWave backhaul architecture is outlined highlighting the most important newly needed functional blocks and in what they differ from a non-mmWave architectures. Next, the challenges and functionality of RRM techniques are discussed, focusing on Routing and Link scheduling algorithms in such BH architecture. Furthermore different possible interactions between RRM functions are explored. Finally, preliminary analytical and experimental study on the performance of different link scheduling and routing functions for mmWave backhauling are provided, highlighting in particular the impact of traffic load and dynamic route selection on BH End to End delay.
This paper proposes an analytical model for the throughput of the enhanced distributed channel access (EDCA) mechanism in the IEEE 802.11p medium-access control (MAC) sublayer. Features in EDCA such as different contention windows (CW) and arbitration interframe space (AIFS) for each access category (AC) and internal collisions are taken into account. The analytical model is suitable for both basic access and the request-to-send/clear-to-send (RTS/CTS) access mode. Different from most of existing 3-D or 4-D Markov-chain-based analytical models for IEEE 802.11e EDCA, without computation complexity, the proposed analytical model is explicitly solvable and applies to four access categories of traffic in the IEEE 802.11p. The proposed model can be used for large-scale network analysis and validation of network simulators under saturated traffic conditions. Simulation results are given to demonstrate the accuracy of the analytical model. In addition, we investigate service differentiation capabilities of the IEEE 802.11p MAC sublayer. © 2011 IEEE.
In this paper, we propose a novel position-based routing protocol designed to anticipate the characteristics of an urban VANET environment. The proposed algorithm utilizes the prediction of the node's position and navigation information to improve the efficiency of routing protocol in a vehicular network. In addition, we use the information about link layer quality in terms of SNIR and MAC frame error rate to further improve the efficiency of the proposed routing protocol. This in particular helps to decrease end-to-end delay. Finally, carry-n-forward mechanism is employed as a repair strategy in sparse networks. It is shown that use of this technique increases packet delivery ratio, but increases end-to-end delay as well and is not recommended for QoS constraint services. Our results suggest that compared with GPSR, our proposal demonstrates better performance in the urban environment. © 2011 IEEE.
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 MAGAZINE8(1)pp. 57-69 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Dianati M, Shen X, Naik K (2011) Cooperation Link Level Retransmission in Wireless Networks, In: Obaidat MS, Misra S (eds.), Cooperative Networking10 Wiley
10 Cooperation Link Level Retransmission in Wireless Networks Mehrdad Dianati1,
Xuemin (Sherman) Shen2 and Kshirasagar Naik2 1Centre for Communication ...
Mehrjoo M, Awad MK, Dianati M, Shen XS (2010) Design of Fair Weights for Heterogeneous Traffic Scheduling in Multichannel Wireless Networks, IEEE TRANSACTIONS ON COMMUNICATIONS58(10)pp. 2892-2902 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Waqar O, Imran MA, Dianati M (2013) On the error analysis of fixed-gain relay networks over composite multipath/shadowing channels, IEEE Vehicular Technology Conference
In this paper, the analysis for the average bit error probability (ABEP) of a dual-hop fixed-gain relay network is conducted. To this end, we consider two different scenarios: 1) the second hop (relay-destination link) is subject to composite multipath/shadowing and the first hop (source-relay link) experiences only multipath fading; 2) the first hop is perturbed by the composite multipath/shadowing and the second hop undergoes only multipath fading. We develop new and exact closed-form expressions of the ABEP for the first scenario in terms of the Meijer-G and Lommel functions. Since the exact closed-form expressions for the second scenario are mathematically intractable, we derive a new approximation and bounds. These approximation and bounds are shown to be tight for medium to high average signal-to-noise ratio (SNR) regime. In addition, we also provide new and relatively simpler asymptotic expressions of the ABEP for both the scenarios. It is shown that some physical insights (e.g., diversity order) of the system can readily be obtained by using these asymptotic expressions. All our analytical results are corroborated by the Monte-Carlo simulations. © 2013 IEEE.
Dianati M, Ling XH, Naik K, Shen XS (2006) A node-cooperative ARQ scheme for wireless ad hoc networks, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY55(3)pp. 1032-1044 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
This paper presents a new multi-channel MAC protocol for Vehicular Ad Hoc Networks, namely, Asynchronous Multi-Channel MAC (AMCMAC). The AMCMAC supports simultaneous transmissions on different service channels, as well as, allowing other nodes to make rendezvous with their provider/receiver or broadcast emergency messages on the control channel. We compare the performance of the proposed protocol with that of IEEE 1609.4 and Asynchronous Multichannel Coordination Protocol (AMCP), in terms of throughput on control and service channels, channel utilization, and the penetration rate of successfully broadcast emergency messages. We demonstrate that AMCMAC outperforms IEEE 1609.4 and AMCP in terms of system throughput by increasing the utilization of control channel and service channels. In addition, AMCMAC mitigates both the multi-channel hidden terminal and missing receiver problems which occur in asynchronous multichannel MAC protocols. © 2011 IEEE.
This paper studies the impacts of vehicular communications on efficiency of traffic in urban areas. We consider a Green Light Optimized Speed Advisory application implementation in a typical reference area and present the results of its performance analysis using an integrated cooperative intelligent transportation systems simulation platform. In addition, we study route alternation using vehicle-to-infrastructure and vehicle-to-vehicle communications. Our interest was to monitor the impacts of these applications on fuel and traffic efficiency by introducing metrics for average fuel consumption, average stop time behind a traffic light and average trip time, respectively. For gathering the results, we implemented two traffic scenarios defining routes through an urban area including traffic lights. The simulations are varied for different penetration rates of application-equipped vehicles, driver's compliance to the advised speed and traffic density. Our results indicate that Green Light Optimized Speed Advisory systems could improve fuel consumption, reduce traffic congestion in junctions and the total trip time
Planning and optimization of 3G networks is more than just frequency allocation and coverage planning, due to the nature of WCDMA coding. It usually involves solution of an NP-Hard problem. In this paper we propose an effective method for optimizing the Common Pilot Channel (CPICH) transmit power, along with maximizing the number of served users and minimizing the number of cell sites and compare use of two meta-heuristic methods: Taboo Search (TS) and Genetic Algorithm (GA) in planning and optimization of UMTS radio networks.
Katsaros K, Dianati M, Roscher K (2012) A position-based routing module for simulation of VANETs in ns-3., SimuToolspp. 345-352 ICST/ACM
This paper investigates collaboration among neighboring Base Stations (BSs) in OFDMA based cellular networks in the absence of a centralized control unit, which is a defining characteristic of 4G wireless networks. We propose a novel scheme for collaboration between the base stations. Monte Carlo simulation based performance analysis demonstrates effectiveness of collaborative resource allocation among adjacent base stations for OFDMA systems, particularly for the users in the cell edges. © 2011 IEEE.
The increasing demand for spectral and energy efficient communication
networks has spurred a great interest in energy harvesting (EH) cognitive radio
networks (CRNs). Such a revolutionary technology represents a paradigm shift in
the development of wireless networks, as it can simultaneously enable the
efficient use of the available spectrum and the exploitation of radio frequency
(RF) energy in order to reduce the reliance on traditional energy sources. This
is mainly triggered by the recent advancements in microelectronics that puts
forward RF energy harvesting as a plausible technique in the near future. On
the other hand, it is suggested that the operation of a network relying on
harvested energy needs to be redesigned to allow the network to reliably
function in the long term. To this end, the aim of this survey paper is to
provide a comprehensive overview of the recent development and the challenges
regarding the operation of CRNs powered by RF energy. In addition, the
potential open issues that might be considered for the future research are also
discussed in this paper.
© Copyright 2015 John Wiley & Sons, Ltd.This paper presents a comprehensive study of the performance of routing protocols in distributed vehicular networks. We propose a novel and efficient routing protocol, namely cross-layer, weighted, position-based routing, which considers link quality, mobility and utilisation of nodes in a cross layer manner to make effective position-based forwarding decisions. An analytic hierarchy process approach is utilised to combine multiple decision criteria into a single weighting function and to perform a comparative evaluation of the effects of aforementioned criteria on forwarding decisions. Comprehensive simulations are performed in realistic representative urban scenarios with synthetic and real traffic. Insights on the effect of different communication and mobility parameters are obtained. The results demonstrate that the proposed protocol outperforms existing routing protocols for vehicular ad hoc networks, including European Telecommunications Standards Institute (ETSI's) proposed greedy routing protocol, greedy traffic aware routing protocol and advanced greedy forwarding in terms of combined packet delivery ratio, end-to-end delay and overhead.
Oredope A, Dianati M, Evans BG, Budhiraja R, Ramamurthi B (2010) Deploying IP Multimedia Subsystem (IMS) Services over Next Generation Networks (NGNs): The IU-ATC Integrated Test Bed., TRIDENTCOM46pp. 727-735 Springer
Zhu X, Zhu H, Dianati M (2013) Analysis of cooperative and competitive spectrum sharing for heterogeneous networks based on differential dynamics model, International Journal of Communication Systems Wiley
SUMMARY: The heterogeneous networks belonging to different service providers form a coalition system for maximizing the profit, where they may either compete or cooperate with each other. In this paper, we introduce the Lokta-Volterra model, a differential dynamics model, to build the competitive and cooperative mechanisms of heterogeneous networks. It considers the natural growth rate of the network itself and competitive and cooperative effects among networks. Then, according to the ordinary differential principle, the stability of the proposed model and its equilibrium points are analyzed. And finally, system performances are evaluated by Vensim that is used for developing, analyzing, and packaging dynamic feedback models. Analysis and simulation results show that the natural growth rate of the network cannot increase its profit, but effective cooperative mechanism among heterogeneous networks can increase the profit of each network. © 2013 John Wiley & Sons, Ltd.
Shi Y, Katsaros K, Han C, Dianati M METHOD FOR COMMUNICATION, SERVER, ROADSIDE UNIT AND NODE,
Virtual multiple-input-multiple-output (MIMO) systems using multiple antennas at the transmitter and a single antenna at each of the receivers have recently emerged as an alternative to point-to-point MIMO systems. This paper investigates the relationship between energy efficiency (EE) and spectral efficiency (SE) for a virtual-MIMO system that has one destination and one relay using compress-and-forward (CF) cooperation. To capture the cost of cooperation, the power allocation (between the transmitter and the relay) and the bandwidth allocation (between the data and cooperation channels) are studied. This paper derives a tight upper bound for the overall system EE as a function of SE, which exhibits good accuracy for a wide range of SE values. The EE upper bound is used to formulate an EE optimization problem. Given a target SE, the optimal power and bandwidth allocation can be derived such that the overall EE is maximized. Results indicate that the EE performance of virtual-MIMO is sensitive to many factors, including resource-allocation schemes and channel characteristics. When an out-of-band cooperation channel is considered, the performance of virtual-MIMO is close to that of the MIMO case in terms of EE. Considering a shared-band cooperation channel, virtual-MIMO with optimal power and bandwidth allocation is more energy efficient than the noncooperation case under most SE values.
Payami S, Shariat M, Ghoraishi M, Dianati M (2015) Effective RF Codebook Design and Channel Estimation for Millimeter Wave Communication Systems,
Dianati M, Tafazolli R, Moessner K (2010) Enabling Tussle-Agile Inter-networking Architectures by Underlay Virtualisation, FUTURE INTERNET - FIS 20096152pp. 81-95 SPRINGER-VERLAG BERLIN
Dianati M, Ling XH, Naik S, Shen XM (2005) A node cooperative ARQ scheme for wireless ad-hoc networks, NETWORKING 2005: NETWORKING TECHNOLOGIES, SERVICES, AND PROTOCOLS; PERFORMANCE OF COMPUTER AND COMMUNICATION NETWORKS; MOBILE AND WIRELESS COMMUNICATIONS SYSTEMS3462pp. 1418-1421 SPRINGER-VERLAG BERLIN
In wireless channels, the bursty nature of block errors render immediate packet retransmissions at the link level ineffective. Cooperative communication is a promising technique to combat the negative impacts of channel fading by providing diverse channels between peers in wireless ad-hoc networks. In this paper, an analytical model is proposed for the throughput of the node cooperative automatic repeat request scheme for wireless ad-hoc networks. The model is based on a two-state Markov model for block errors in the wireless fading channels. Simulation results are given to demonstrate effectiveness of the analytical model
Navaratnarajah S, Dianati M, Imran MA (2015) Analysis of Energy Efficiency on the Cell Range Expansion for Cellular-WLAN Heterogeneous Network, 2015 INTERNATIONAL WIRELESS COMMUNICATIONS & MOBILE COMPUTING CONFERENCE (IWCMC)pp. 514-519 IEEE
Katranaras E, Imran MA, Dianati M (2013) Energy-aware clustering for multi-cell joint transmission in LTE networks, 2013 IEEE International Conference on Communications Workshops, ICC 2013pp. 419-424
This paper investigates the energy-aware clustering of cooperating base stations in the downlink of cellular networks. The focus of this work is on static clustering deployments for LTE systems when joint signal precoding is employed at multiple base stations. We demonstrate that properly planned clustering can provide the desired balance between network spectral and energy efficiency. To this end, we compare the overall energy consumption of various clustered cooperation layouts while considering different target performance metrics at user end. Our evaluations for various inter-site distance deployments in a practical macrocell scenario unveil the individual parameters controlling the energy effectiveness of a clustering strategy. In fact, it is shown that the choice of the optimum clustering layout depends on: 1) the specific service demands; 2) the deployment density of the network and; 3) on the ability of the base stations to jointly adjust their transmit power. Ultimately, we provide a general framework for choosing the most appropriate cooperation set of base stations in energy-aware networks. © 2013 IEEE.
Mi D, Dianati M, Muhaidat S, Chen Y (2015) A Novel Antenna Selection Scheme for Spatially Correlated Massive MIMO Uplinks with Imperfect Channel Estimation., VTC Springpp. 1-6 IEEE
Waqar O, Imran M, Dianati M, Tafazolli R (2014) Energy Consumption Analysis and Optimization of BER-Constrained Amplify-and-Forward Relay Networks, IEEE Transactions on Vehicular Technology IEEE
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
Jiang J, Dianati M, Imran MA, Tafazolli R (2013) On the Energy Efficiency of MIMO Channels in Correlated Rayleigh Fading Environment., EW VDE-Verlag
Taghipour MM, Han C, Dianati M (2011) Improving reliability of emergency message dissemination in VANETs, IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conferencepp. 1200-1205
This paper proposes a novel MAC sub-layer mechanism in order to improve reliability of emergency message dissemination in Vehicular Ad-hoc Networks. We consider a VANET that uses IEEE 802.11e MAC sub-layer. We propose enhancements in the multi-access policies of the original IEEE 802.11e standard in order to automatically reduce the volume of data traffic for non-safety applications allowing less contention for safety related message dissemination. Comprehensive simulation results in different scenarios demonstrate the effectiveness of the proposed scheme in terms of packet reception rate and medium access delay for safety related applications. © 2011 IEEE.
Saeed A, Katranaras E, Dianati M, Imran MA (2015) Control and Data Channel Resource Allocation in OFDMA Heterogeneous Networks, JOURNAL OF SIGNAL PROCESSING SYSTEMS FOR SIGNAL IMAGE AND VIDEO TECHNOLOGY85(2)pp. 183-199 SPRINGER
Dianati M, Shen XM, Naik S (2005) A new fairness index for radio resource allocation in wireless networks, 2005 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, VOLS 1-4pp. 712-717 IEEE
Peev M, Pacher C, Alleaume R, Barreiro C, Bouda J, Boxleitner W, Debuisschert T, Diamanti E, Dianati M, Dynes JF, Fasel S, Fossier S, Fuerst M, Gautier J-D, Gay O, Gisin N, Grangier P, Happe A, Hasani Y, Hentschel M, Huebel H, Humer G, Laenger T, Legre M, Lieger R, Lodewyck J, Loruenser T, Luetkenhaus N, Marhold A, Matyus T, Maurhart O, Monat L, Nauerth S, Page J-B, Poppe A, Querasser E, Ribordy G, Robyr S, Salvail L, Sharpe AW, Shields AJ, Stucki D, Suda M, Tamas C, Themel T, Thew RT, Thoma Y, Treiber A, Trinkler P, Tualle-Brouri R, Vannel F, Walenta N, Weier H, Weinfurter H, Wimberger I, Yuan ZL, Zbinden H, Zeilinger A (2009) The SECOQC quantum key distribution network in Vienna,NEW JOURNAL OF PHYSICS11ARTN 075001
IOP PUBLISHING LTD
Alléaume R, Branciard C, Bouda J, Debuisschert T, Dianati M, Gisin N, Godfrey M, Grangier P, Länger T, Lütkenhaus N, Monyk C, Painchault P, Peev M, Poppe A, Pornin T, Rarity J, Renner R, Ribordy G, Riguidel M, Salvail L, Shields A, Weinfurter H, Zeilinger A (2014) Using quantum key distribution for cryptographic purposes: A survey.,Theor. Comput. Sci.560pp. 62-81
Katsaros K, Dianati M, Le L (2013) Effective implementation of location services for VANETs in hybrid network infrastructures, 2013 IEEE International Conference on Communications Workshops, ICC 2013pp. 521-525
In this paper we propose and evaluate a heterogeneous architecture for location service in vehicular environments. The proposed Location Service utilizes the infrastructure of cellular networks to offload the Dedicated Short Range Communication (DSRC) systems from the signalling overhead required for the location service. We evaluate the performance of such a hybrid solution in terms of overhead and end-to-end delay. The results suggest that a heterogeneous network with an IEEE 802.11p access network for data delivery and a LTE network for Location Service can provide better system performance in high density and high load scenarios. © 2013 IEEE.
Alleaume R, Bouda J, Branciard C, Debuisschert T, Dianati M, Gisin N, Godfrey M, Grangier P, Langer T, Leverrier A, Lutkenhaus N, Painchault P, Peev M, Poppe A, Pornin T, Rarity J, Renner R, Ribordy G, Riguidel M, Salvail L, Shields A, Weinfurter H, Zeilinger A (2007) SECOQC White Paper on Quantum Key Distribution and Cryptography, ArXiv
The SECOQC White Paper on Quantum Key Distribution and Cryptography is the
outcome on a thorough consultation and discussion among the participants of the
European project SECOQC (www.secoqc.net). This paper is a review article that
attempts to position Quantum Key Distribution (QKD) in terms of cryptographic
applications. A detailed comparison of QKD with the solutions currently in use
to solve the key distribution problem, based on classical cryptography, is
provided. We also detail how the work on QKD networks lead within SECOQC will
allow the deployment of long-distance secure communication infrastructures
based on quantum cryptography. The purpose of the White Paper is finally to
promote closer collaboration between classical and quantum cryptographers. We
believe that very fruitful research, involving both communities, could emerge
in the future years and try to sketch what may be the next challenges in this
In this paper, we introduce the concept of average per-user rate to the multiuser Multiple-Input, Multiple-Output (MIMO) system with the frequency domain packet scheduler (FDPS) at base stations, which provides an estimate of the rate that the system could provide for each admitted user. The proposed admission control is designed by comparing the user's quality of service (QoS) requirements with the transmission rate that the system can offer. The analytical model is based on the generalized 3GPP LTE downlink transmission for which two Spatial Division Multiplexing (SDM) multiuser MIMO schemes are investigated, namely, Single User (SU) and Multi-user (MU) MIMO schemes. The main contribution of this paper is the derivation of the achievable rate for each user in the SDM MIMO systems based on a mathematical model of the Signal to Interference plus Noise Ratio (SINR) distribution with the frequency domain packet scheduler. The achievable rate provides insights into the system's performance from a different perspective. © 2012 IEEE.
Dianati M, Shen XS, Naik K (2005) Efficient Scheduling for the Downlink of CDMA Cellular Networks using Base Station Selection Diversity, 2ND INTERNATIONAL CONFERENCE ON BROADBAND NETWORKS (BROADNETS 2005)pp. 406-411 IEEE
This paper investigates energy efficiency (EE) performance of a virtual multiple-input multiple- output (MIMO) wireless system using the receiver- side cooperation with the compress-and-forward protocol. We derive a linear approximation of EE as a function of spectral efficiency (SE) in the low SE operation regime. In addition, we obtain a closed-form lower bound for EE which is valid for both low and high SE regions. This lower bound can be used for optimizing the power allocation between the transmitter and the relay in order to minimize the overall energy per bit consumption in the system. Both analytical and simulation results demonstrate that the virtual MIMO system using the receiver-side cooperation outperforms the multiple- input single-output (MISO) case in terms of energy efficiency. Finally we show that, with the optimal power allocation, the virtual-MIMO system achieves an EE performance close to that of an ideal MIMO system.
Saeed A, Katranaras E, Dianati M, Imran MA (2016) Dynamic femtocell resource allocation for managing inter-tier interference in downlink of heterogeneous networks, IET COMMUNICATIONS10(6)pp. 641-650 INST ENGINEERING TECHNOLOGY-IET
Ling X, Dianati M, Mark JW, Shen X (2006) A link performance model for multi-user wireless fading channels, ACM International Conference Proceeding Series191
The two-state Markov chain has been widely used to model fading channels in the performance study of upper-layer communication protocols in wireless networks. It can be used to model transmission success/failure based on the physical characteristics of the transmission channel. However, for shared wireless links, packet transmission depends on both the status of the link and the scheduling strategy used. In this poster, we propose a novel four-state Markov model, which takes into consideration the impacts of channel fading and scheduling on packet transmission over shared wireless links. It is further abstracted to an effective two-state Markov chain to facilitate analytical performance evaluation. To demonstrate the efficacy of the proposed model, we apply it to study the throughput, delay and delay jitter of a saturated traffic source, and the packet dropping probability at the network layer for data traffic under a buffer overflow dropping policy. Simulation results to demonstrate the reasonableness of the proposed model are also presented. © 2006 ACM.
In this paper, we propose a novel scheduling scheme for the downlink of IEEE 802.16 networks. A scheduler at the Base Station (BS) decides the order of downlink bursts to be transmitted. The decision is made based on the quality of the channel and the history of transmissions of each Subscriber Station (SS). The scheduler takes advantage of temporal channel fluctuations to increase the BS's throughput and maintain fairness by balancing the long term average throughput of SSs. Simulation results are given to demonstrate the performance of the proposed scheduling scheme. © 2006 ACM.
© 2014 IEEE.This paper examines the uplink of cellular systems employing base station cooperation for joint signal processing. We consider clustered cooperation and investigate effective techniques for managing inter-cluster interference to improve users' performance in terms of both spectral and energy efficiency. We use information theoretic analysis to establish general closed form expressions for the system achievable sum rate and the users' Bit-per-Joule capacity while adopting a realistic user device power consumption model. Two main inter-cluster interference management approaches are identified and studied, i.e., through: 1) spectrum re-use; and 2) users' power control. For the former case, we show that isolating clusters by orthogonal resource allocation is the best strategy. For the latter case, we introduce a mathematically tractable user power control scheme and observe that a green opportunistic transmission strategy can significantly reduce the adverse effects of inter-cluster interference while exploiting the benefits from cooperation. To compare the different approaches in the context of real-world systems and evaluate the effect of key design parameters on the users' energy-spectral efficiency relationship, we fit the analytical expressions into a practical macrocell scenario. Our results demonstrate that significant improvement in terms of both energy and spectral efficiency can be achieved by energy-aware interference management.
Han C, Dianati M, Tafazolli R, Kernchen R (2010) Throughput Analysis of the IEEE 802.11p Enhanced Distributed Channel Access Function in Vehicular Environment, pp. 1-5
This paper proposes an analytical model for the throughput of the Enhanced Distributed Channel Access (EDCA)mechanism in IEEE 802.11p MAC sub-layer. Features in EDCA such as different Contention Windows (CW) and Arbitration Interframe Space (AIFS) for each Access Category (AC), and internal collisions are taken into account. The analytical model is suitable for both basic access and the Request-To-Send/Clear-To-Send (RTS/CTS) access mode. The proposed analytical model is validated against simulation results to demonstrate its accuracy
Saeed A, Akbari A, Dianati M, Imran MA (2013) Energy Efficiency Analysis for LTE Macro-Femto HetNets., EW VDE-Verlag
Akbari A, Imran MA, Dianati M, Tafazolli R (2013) Weighted average energy efficiency contours for uplink channels, IEEE Vehicular Technology Conference
The continuous increase in the energy consumption of wireless networks has led to extensive research and development into energy-efficient communications. Towards this objective, this paper employs a novel technique for maximizing the energy efficiency (EE) of wireless networks, using weighted average EE contours with multiple decoding policies (DPs), where users are prioritized based on different criteria such as channel condition. Moreover, our EE based resource allocation method is extended such that other system targets such as rate-fairness and quality of service (QoS) are satisfied. Results indicate that our EE-based resource allocation scheme achieves the highest EE when DP 2 is employed, i.e. the user with the best channel gain achieves its single user bound, whilst other users experience residual interference. Moreover, both the fairness and QoS constraints increase user satisfaction, in terms of achievable data rate, which comes at the cost of a higher transmit power, and therefore lower EE. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.
Alléaume R, Lütkenhaus N, Renner R, Grangier P, Debuisschert T, Ribordy G, Gisin N, Painchault P, Pornin T, Salvail L, Riguidel M, Shields A, Länger T, Peev M, Dianati M, Leverrier A, Poppe A, Bouda J, Branciard C, Godfrey M, Rarity J, Weinfurter H, Zeilinger A, Monyk C (2009) Quantum key distribution and cryptography: a survey., Classical and Quantum Information Assurance Foundations and Practice09311 Schloss Dagstuhl - Leibniz-Zentrum für Informatik, Germany
Dianati M, Alleaume R, Gagnaire M, Shen XS (2008) Architecture and protocols of the future European quantum key distribution network, SECURITY AND COMMUNICATION NETWORKS1(1)pp. 57-74 JOHN WILEY & SONS LTD
Saeed A, Katranaras E, Dianati M, Imran MA (2015) Control and Data Channel Resource Allocation in Macro-Femto Heterogeneous Networks, 2015 INTERNATIONAL WIRELESS COMMUNICATIONS & MOBILE COMPUTING CONFERENCE (IWCMC)pp. 1272-1276 IEEE
This paper proposes a novel distributed asynchronous multichannel medium access control (MAC) scheme for large-scale vehicular ad hoc networks (VANETs), i.e., asynchronous multichannel medium access control with a distributed time-division multiple-access mechanism (AMCMAC-D). The proposed scheme supports simultaneous transmissions on different service channels while allowing rendezvous and broadcast of emergency messages on the control channel. The scheme is distributed, because it handles access to the shared control channel for different access categories without relying on the beacon frames from roadside units. This condition eliminates the overhead that is associated with channel allocation, making the proposed scheme suitable for large-scale networks in terms of the number of active nodes. Service differentiation in the proposed scheme is enhanced by allocating different numbers of time slots for different access categories. We compare the performance of the proposed scheme with the IEEE 1609.4 standard and the asynchronous multichannel Coordination Protocol (AMCP) in terms of throughput, packet delivery rate, collision rate, utilization of service channels, service differentiation, and the penetration rate of noncollided emergency messages. The results show that AMCMAC-D outperforms the IEEE 1609.4 standard and AMCP in terms of system throughput by increasing the utilization of the control channel and service channels. The proposed scheme also demonstrates better performance in terms of packet delivery rate, collision rate on a service channel, load balancing, and service differentiation. Finally, AMCMAC-D mitigates the multichannel hidden terminal and missing receiver problems, which occur in asynchronous multichannel MAC schemes. © 1967-2012 IEEE.
Navaratnarajah S, Saeed A, Dianati M, Imran ML (2013) Energy efficiency in heterogeneous wireless access networks, IEEE Wireless Communications20(5)pp. 37-43
In this article, we bring forward the important aspect of energy savings in wireless access networks. We specifically focus on the energy saving opportunities in the recently evolving heterogeneous networks (HetNets), both Single-RAT and Multi-RAT. Issues such as sleep/wakeup cycles and interference management are discussed for co-channel Single-RAT HetNets. In addition to that, a simulation based study for LTE macro-femto HetNets is presented, indicating the need for dynamic energy efficient resource management schemes. Multi-RAT HetNets also come with challenges such as network integration, combined resource management and network selection. Along with a discussion on these challenges, we also investigate the performance of the conventional WLAN-first network selection mechanism in terms of energy efficiency (EE) and suggest that EE can be improved by the application of intelligent call admission control policies. © 2013 IEEE.
Quantum Key Distribution (QKD) is an alternative key distribution technique that, unlike the classical approaches, can provide unconditionally secure keys for data communications over public communication networks. The European projet Secoqc (Secure Communication based on Quantum Cryptography) aims at developing a global network for unconditionally secure key distribution. This paper specifies the major elements of the transport layer protocols of the Secoqc QKD network. © 2007 IEEE.
This paper proposes a Green Light Optimized Speed Advisory (GLOSA) application implementation in a typical reference area, and presents the results of its performance analysis using an integrated cooperative ITS simulation platform. Our interest was to monitor the impacts of GLOSA on fuel and traffic efficiency by introducing metrics for average fuel consumption and average stop time behind a traffic light, respectively. For gathering the results we implemented a traffic scenario defining a single route through an urban area including two traffic lights. The simulations are varied for different penetration rates of GLOSA-equipped vehicles and traffic density. Our results indicate that GLOSA systems could improve fuel consumption and reduce traffic congestion in junctions. © 2011 IEEE.
Shi Y, Katsaros K, Han C, Dianati M METHOD FOR TRANSMITTING TRAFFIC, TERMINAL DEVICE AND NETWORK NODE,
Suthaputchakun C, Sun Z, Dianati M (2013) Trinary Partition Black-Burst based Broadcast Protocol for Emergency Message dissemination in VANET, IEEE Wireless Communications and Networking Conference, WCNCpp. 2244-2249
In this paper, we analyze the current binary partition multi-hop broadcast protocol and propose an enhanced solution, namely, Trinary Partition Black-Burst based Broadcast Protocol (3P3B) for Emergency Message (EM) dissemination. 3P3B provides low and constant latency regardless density and size of networks compared to existing solutions. It also enhances message dissemination speed and message progress distance. The main technique in the 3P3B is that 3P3B uses mini-slot DIFS to give a preemptive priority to very urgent EMs and deploys a trinary partition mechanism to select the furthest forwarder of the next communication hop. We prove that 3P3B recues the delay, increases dissemination speed, message progress distance, and outperforms the well-known existing broadcast protocols for EM dissemination in VANET. © 2013 IEEE.
The present invention relates to the field of communication technologies, and in particular, to transmitting communication messages.
The present invention generally relates to the field of communications technologies, and more particularly to a method for communication, a server, a
roadside unit and a node.
CARMA (Cloud-Assisted Real-time Methods for Autonomy) is a highly innovative and challenging project which aims to develop and test cooperative automated driving technology, based on a distributed control system. The approach is enabled by an ultra-low latency and highly reliable cloud-based infrastructure accessed through 5G. This paper describes the 3-tier distributed computing architecture used in the project comprising the Vehicle, the Edge cloud and the Core. It describes a methodology to test a set of use cases representative of both urban and highway driving and explores the key challenges in such an approach. The ?rst technical challenge is the design of a mobile edge cloud infrastructure that is able to support real-time and safety critical applications. Another non-trivial problem is that of cyber-security for such a real-time cyber physical system. Progress during the first year of this five year project is described.
Multi-user (MU) massive multiple-input-multiple-output (MIMO) is one of the promising technologies for the 5th Generation of wireless communication systems. However, as an emerging technology, various technical challenges that hinder practical use of massive MIMO need to be addressed, e.g., imperfections on channel estimation and channel reciprocity. The overall objective of the proposed research is to investigate some of the key practical challenges of implementation of the massive MIMO system and propose effective solutions for those problems.
First, in order to realise promised benefits of massive MIMO, there is a need for a highly accurate technique for provisioning of channel state information (CSI). However, the acquisition of CSI can be considerably influenced by imperfect channel estimation in practice. We therefore analyse the impact of channel estimation error on the performance of massive MIMO uplinks with the considerations of the channel correlation over space. We then propose a novel antenna selection scheme by exploiting the sparsity of the channel gain matrix at the received end, which significantly reduces implementation overhead and complexity compared to the well-adopted scheme, without degrading the system performance.
Second, it is known that channel reciprocity in time-division duplexing (TDD) massive MIMO systems can be exploited to reduce the overhead required for the acquisition of CSI. However, perfect reciprocity is unrealistic in practical systems due to random radio-frequency (RF) circuit mismatches in uplink and downlink channels. We model and analyse the impact of the RF mismatches by taking into account the channel estimation error. We derive closed-form expressions of the output signal-to-interference-plus- noise ratio for typical linear precoding schemes, and further investigate the asymptotic performance of the considered precoding schemes to provide insights into the practical system designs, including guidelines for the selection of the effective precoding schemes.
Third, our theoretical model for analysing the effect of channel reciprocity error on massive MIMO systems reveals that the imperfections in channel reciprocity might become a performance limiting factor. In order to compensate for these imperfections, we present and investigate two calibration schemes for TDD-based MU massive MIMO systems, namely, relative calibration and inverse calibration. In particular, the design of the proposed inverse calibration takes into account a compound effect of channel reciprocity error and channel estimation error. To compare two calibration schemes, we derive closed-form expressions for the ergodic sum-rate and the receive mean-square error for downlinks. We demonstrate that the proposed inverse calibration outperforms the relative calibration, thanks to its greater robustness to the compound effect of both errors.
This letter proposes a novel graph-based multi-cell scheduling framework to efficiently mitigate downlink inter-cell interference in small cell OFDMA networks. This framework incorporates dynamic clustering combined with channel-aware resource allocation to provide tunable quality of service measures at different levels. Our extensive evaluation study shows that a significant improvement in user's spectral efficiency is achievable, while also maintaining relatively high cell spectral efficiency via empirical tuning of re-use factor across the cells according to the required QoS constraints.
Channel reciprocity in time-division duplexing (TDD) massive MIMO (multiple-input multiple-output) systems can be exploited to reduce the overhead required for the acquisition of channel state information (CSI). However, perfect reciprocity is unrealistic in practical systems due to random radio-frequency (RF) circuit mismatches in uplink and downlink channels. This can result in a significant degradation in the performance of linear precoding schemes which are sensitive to the accuracy of the CSI. In this paper, we model and analyse the impact of RF mismatches on the performance of linear precoding in a TDD multi-user massive MIMO system, by taking the channel estimation error into considerations. We use the truncated Gaussian distribution to model the RF mismatch, and derive closed-form expressions of the output SINR (signal-to-interference-plus-noise ratio) for maximum ratio transmission and zero forcing precoders. We further investigate the asymptotic performance of the derived expressions, to provide valuable insights into the practical system designs, including useful guidelines for the selection of the effective precoding schemes. Simulation results are presented to demonstrate the validity and accuracy of the proposed analytical results.
A novel approach for implementation of opportunistic scheduling without explicit feedback channels is proposed in this paper, which exploits the existing, ARQ signals instead of feedback channels to reduce the complexity of implementation. Monte Carlo simulation results demonstrate the efficacy of the proposed approach in harvesting multiuser diversity gain. The proposed approach enables implementation of opportunistic scheduling, in a variety of wireless networks, such as the IEEE 802.11, without feedback facilities for collecting partial channel state information from users.
Motivated by increased interests in energy efficient
communication systems, the relation between energy efficiency
(EE) and spectral efficiency (SE) for multiple-input multipleoutput
(MIMO) systems is investigated in this paper. To provide
insight into the design of practical MIMO systems, we adopt
a realistic power model, as well as consider both independent
Rayleigh fading and semicorrelated fading channels. We derive
a novel and closed-form upper bound for the system EE as a
function of SE. This upper bound exhibits a great accuracy
for a wide range of SE values, and thus can be utilized for
explicitly assessing the influence of SE on EE, and analytically
addressing the EE optimization problems. Using this tight EE
upper bound, our analysis unfolds two EE optimization issues:
Given the number of transmit and receive antennas, an optimum
value of SE is derived such that the overall EE can be maximized;
Given a specific value of SE, the optimal number of antennas is
derived for maximizing the system EE.
There has recently been a real demand to design and deploy mobile communication networks
that consume significantly less energy compared to the existing s ystems. The main thrust of
this research focuses on investigation of the impacts of radio resource allocation schemes in the
current state-of-the-art Orthogonal Frequency Division Multiple Access (OFDMA) systems
on energy efficiency (EE) o f modern Radio Access Networks ( RANs), a s well a s design of
effective solutions to reduce RAN energy consumption in such networks.
Due to data traffic fluctuation of communication networks, there are often many unused radio
resource blocks in OFDMA systems. Efficient allocation of these surplus resource blocks can
lead to considerable energy savings. One of the key objectives of this thesis is to exploit
this opportunity by designing practical and effective radio resource allocation techniques that
exploit fundamental trade-off between energy consumption and bandwidth by reducing energy
consumption of the RAN while providing the required quality of service (QoS) for the network
users. The basic concept here is to exploit fluctuations of data traffic in the network.
Specifically, a novel e nergy e fficient re source al location te chnique, fo r low lo ad tr affic conditions
is proposed. This technique is then applied to three bespoke scheduling schemes,
namely Round Robin (RR), Best Channel Quality Indicator (BCQI), and Proportional Fair (PF)
for performance assessment. Comprehensive evaluation of the proposed scheduling schemes
demonstrates that adopting the proposed resource allocation technique significantly enhances
the performance of RAN in terms of energy consumption in comparison with the conventional
schemes such as the three aforementioned schedulers.
Finding an optimal method for surplus resource allocation is firstly modelled as an optimisation
problem which is subsequently solved using dynamic programming. In this context, a
Knapsack Problem (KP) is adopted to find an optimal solution for a single-cell s cenario. The
proposed heuristic method is simulated using Equal Power (EP) and Water Filling (WF) algorithms
for surplus resource allocation. It is shown that the optimal solution is achieved using
the WF algorithm leading to an EE saving of 60% compared to the greedy KP solution, whilst
significantly lower computational complexity.
The optimality of the proposed algorithm is evaluated in a multi-cell scenario to take into
Connected vehicles are promoted with the use of different communication technologies for diverse applications and services. There is an ongoing debate in the research and industry communities whether short range communications based on IEEE 802.11p or cellular based on 3GPP LTE should be used for vehicular communications. In this paper, we propose a mechanism to utilise both short range and cellular communications simultaneously in a cost efficient way while providing the required quality of service to the users. A host connected to multiple networks is referred to as a multi-homed node and Stream Control Transmission Protocol (SCTP) is an IETF standard which supports multi-homing. We propose an extension to SCTP that takes into account not only path quality but also the cost of using each network. It is shown that the combination of QoS and cost information increases economic benefits for provider and end-users, while providing increased packet throughput.
In this paper, we investigate the impacts of different radio propagation environments on the performance of emergency message dissemination Vehicular Ad hoc Networks (VANETs). We compared the performances of the benchmark existing broadcast protocols for Emergency Message Dissemination in VANETs. We consider three different propagation models, namely, Log-Normal Shadowing, Longley-Rice, and Nakagami to model six different simulation scenarios of both highway and urban areas. The objective is to provide a qualitative assessment of the protocols applicability in different vehicular scenarios. It is demonstrated that Trinary Partition Black-Burst based Broadcast Protocol (3P3B) reduces the communication delay, increases dissemination speed, increase reliability, and outperforms the well-known existing broadcast protocols for emergency message dissemination in VANETs in all propagation environments. The benchmark protocols achieve high performance in various vehicular scenarios both in highway and urban areas. However, there is still some reliability issue needed to be addressed by all existing protocols, such as communications in a very crowded city where the received communication signal is strongly distorted.
In this paper, we propose a multihop broadcast protocol for dissemination of time-critical emergency messages (EMs) in vehicular ad hoc networks (VANETs), where the IEEE 802.11p technology is used for communication among the nodes. The proposed trinary partitioned black-burst-based broadcast protocol (3P3B) consists of two primary mechanisms. First, a mini distributed interframe space (DIFS) in a medium access control (MAC) sublayer is introduced to give the time-critical EMs a higher access priority to the communication channel compared with other messages. Second, a trinary partitioning is designed to iteratively partition the communication range into small sectors. The trinary partitioning mechanism allows the farthest possible vehicle in the farthest sector from the sender node to perform forwarding to increase the dissemination speed by reducing the number of forwarding hops. In addition, 3P3B reduces the contention period jitter, which is independent of the density of vehicles, resulting in a more stable contention period. Analytical models are proposed for performance evaluation in conjunction with simulation-based performance analysis. The results demonstrate that 3P3B outperforms benchmarks of the existing broadcast protocols in VANETs in terms of the average message dissemination speed, message progress, communication delay, and packet delivery ratio.
Massive multiple-input multiple-output (MIMO) technology is considered as one of the enabling technologies to scale up the data rates for the future communication systems. Traditional MIMO systems employ digital beamforming where each antenna element is equipped with one radio frequency (RF) chain. When the number of the antennas are scaled up, the cost and power consumption of massive MIMO systems also increase significantly. Recently, hybrid analog-and-digital beamformers have attracted a lot of attention as a cost effective approach to benefit from the advantages of massive MIMO. In hybrid structure, a small number of RF chains are connected to a large number of antennas through a network of phase shifters. The optimal hybrid beamforming problem is a complex nonconvex optimization due to the nonconvex constraint imposed by phase shifters. The overall objective of this thesis is to provide simple and effective hybrid beamforming solutions for narrowband point-to-point and multiuser massive MIMO scenarios.
Firstly, hybrid beamforming problem for a point-to-point communication system with perfect channel state information (CSI) is investigated, and an effective codebook based hybrid beamforming with low resolution phase shifters is proposed which is suitable for sparse scattering channels. Then, by leveraging the properties of massive MIMO, an asymptotically optimal hybrid beamforming solution as well as its closed-form formula will be presented. It will be shown that the proposed method is effective in both sparse and rich scattering propagation environments. In addition, the closed-form expression and lower-bounds for the achievable rates are derived when analog and digital phase shifters are employed.
Secondly, hybrid beamforming problem to maximise the total sum-rate for the downlink of multiuser MIMO is investigated, and an effective solution as well as its closed-form expression for this system is proposed. The presented solutions for the single-antenna and multiantenna scenarios are shown to be effective as they can achieve a similar sum-rate as digital beamforming can reach. In addition, it is shown that the proposed technique with low-cost low resolution phase shifters at the RF beamformer demonstrates a comparable performance to that of a hybrid beamformer with an expensive analog beamformer.
Finally, two novel hybrid beamforming techniques are proposed to reduce the power consumption at the RF beamformer. Defining a threshold level, it is s
For an autonomous vehicle to operate safely and effectively, an accurate and robust localisation system is essential. While there are a variety of vehicle localisation techniques in literature, there is a lack of effort in comparing these techniques and identifying their potentials and limitations for autonomous vehicle applications. Hence, this paper evaluates the state-of-the-art vehicle localisation techniques and investigates their applicability on autonomous vehicles. The analysis starts with discussing the techniques which merely use the information obtained from on-board vehicle sensors. It is shown that although some techniques can achieve the accuracy required for autonomous driving but suffer from the high cost of the sensors and also sensor performance limitations in different driving scenarios (e.g. cornering, intersections) and different environmental conditions (e.g. darkness, snow). The paper continues the analysis with considering the techniques which benefit from off-board information obtained from V2X communication channels, in addition to vehicle sensory information. The analysis shows that augmenting off-board information to sensory information has potential to design low-cost localisation systems with high accuracy and robustness however their performance depends on penetration rate of nearby connected vehicles or infrastructure and the quality of network service.
Intelligent Transportation Systems (ITS) apply Information and Communication Technologies (ICT) to improve safety and efficiency as well as the passenger experience in modern transport systems. It is envisaged that dynamic vehicular networks, particularly, Vehicular Ad-hoc Networks (VANETs) based on dedicated short-range communications (DSRC) and cellular networks, will be important parts of the future ITS. Unlike traditional communication networks, VANETs are highly dynamic systems resulting in significant reliability issues for the communication protocols. In addition, cellular networks incur notable usage cost. Motivated by this, we investigate efficient and reliable geo-routing and transport protocols aimed at VANETs and VANET/cellular hybrid architectures.
Specifically, first we develop an innovative, unicast, cross-layer, weighted, position-based routing protocol (CLWPR) that takes into account mobility and cross layer information about neighbour nodes. A heuristic algorithm based on analytic hierarchy process (AHP) is employed to combine multiple decision criteria into a unique weight parameter used to select the node to which the packet is forwarded. Comprehensive simulations are performed in realistic representative urban scenarios with synthetic and real traffic. Insights on the effect of different communication and environment parameters are obtained. The results demonstrate that the proposed protocol outperforms existing routing protocols for VANETs, including ETSI's proposed greedy routing protocol, GyTAR, and AGF in terms of combined packet delivery ratio, end-to-end delay, and overhead.
To efficiently distribute location information, required for the proper functionality of geo-routing, we develop a centralised Location Service. Exploiting the availability of two interfaces (DSRC and LTE) in a hybrid system, we propose separation of signalling and data traffic. The former is transferred over a cellular network and the later over a short range ad-hoc network. For the evaluation of the proposed scheme, we develop an analytical model of the upper bound delay based on stochastic network calculus (SNC) theory. We compare the upper-bounds of three networks, namely a pure short-range ad-hoc network, a pure cellular based on 3GPP LTE and the proposed hybrid with signalling on cellular and data on ad-hoc network. The results of our investigation suggest that hybrid networks can significantly improve performance of vehicular networks in terms of end-to-end delay both for data and signalling traffic.
In the light of these findings, we investigate transport protocols for hybrid networks benefiting from multi-homing support. As Stream Control Transmission Protocol (SCTP) is one IETF standard that supports multi-homing, we develop an analytical model for throughput calculation of a round-trip time (RTT)-aware SCTP variant.Finally, we propose a novel SCTP scheme that takes into account not only path quality but also the cost of using each network. We show that the combination of QoS and cost information increases economic benefits for provider and end-users, while providing increased packet throughput.
Exploiting channel reciprocity, time-divisionduplexing
(TDD) operated massive multiple-input multipleoutput
(MIMO) systems are able to acquire the channel state
information with a reasonable overhead of channel estimation.
However, in practical scenarios, the imperfections in channel
reciprocity can significantly degrade the system performance.
In this work, we propose a novel self calibration scheme for the
maximum ratio transmission in TDD multi-user massive MIMO
systems to compensate for the imperfect channel reciprocity,
with considerations of imperfect channel estimation. The
proposed scheme shows the greater robustness to a compound
effect of channel reciprocity error and channel estimation error,
compared with the traditional self calibration scheme that is
widely used in massive MIMO systems.
Vehicle platooning is a promising cooperative driving
vision to mitigate issues in road transportation and it leverages
on the use of distributed control systems to precisely control
each vehicle in the fleet. This paper investigates a fully adaptive
platoon control solution made possible by the advent of more
reliable communication channels and off-board cloud computing
systems. The components of the platoon control system, i.e.,
the platoon network topology and the distributed controllers,
adapt based on the relative motion of the vehicles in the
fleet, thus allowing the platoon to self-organise the interactions
among the platoon members and the control gains to create
and maintain the cooperative platoon motion. Furthermore, the
adaptive mechanism to adjust the control gains is equipped with a
Ã-modification strategy to keep the control gains bounded in any
working condition. Numerical results show the effectiveness of
control method to make a heterogeneous platoon a self-organising
network of intelligent vehicles, while also reducing the number
of the communication links required to establish the cooperative
This paper presents a functional architecture for
controlling and managing platoons of vehicles assisted by a
cloud computing platform for passenger vehicles in mixed
traffic scenarios. The architecture modules are distributed in
the three separate logical layers suggested by the on-going
CARMA (Cloud-Assisted Real-time Methods for Autonomy)
research project which aims to develop and test cooperative
automated driving technologies and distributed control systems.
The architecture also exploits the potential of the CARMA
platform both in terms of computing and data sharing.
With self-driving vehicles being pushed towards
the main-stream, there is an increasing motivation towards
development of systems that autonomously perform manoeuvres
involving combined lateral-longitudinal motion (e.g., lanechange,
merge, overtake, etc.). This paper presents a situational
awareness and trajectory planning framework for performing
autonomous overtaking manoeuvres. A combination of a potential
field-like function and reachability sets of a vehicle are used
to identify safe zones on a road that the vehicle can navigate
towards. These safe zones are provided to a model predictive
controller as reference to generate feasible trajectories for a
vehicle. The strengths of the proposed framework are: (i) it
is free from non-convex collision avoidance constraints, (ii)
it ensures feasibility of trajectory, and (iii) it is real-time
implementable. A proof of concept simulation is shown to
demonstrate the ability to plan trajectories for high-speed
In time-division-duplexing (TDD) massive multipleinput
multiple-output (MIMO) systems, channel reciprocity is
exploited to overcome the overwhelming pilot training and
the feedback overhead. However, in practical scenarios, the
imperfections in channel reciprocity, mainly caused by radiofrequency
mismatches among the antennas at the base station
side, can significantly degrade the system performance and might
become a performance limiting factor. In order to compensate
for these imperfections, we present and investigate two new
calibration schemes for TDD-based massive multi-user MIMO
systems, namely, relative calibration and inverse calibration.
In particular, the design of the proposed inverse calibration
takes into account a compound effect of channel reciprocity
error and channel estimation error. We further derive closedform
expressions for the ergodic sum rate, assuming maximum
ratio transmissions with the compound effect of both errors. We
demonstrate that the inverse calibration scheme outperforms the
traditional relative calibration scheme. The proposed analytical
results are also verified by simulated illustrations.
Energy harvesting (EH), which refers to replenishing energy from the environment, is demonstrated to be a promising approach in reducing the operational expenses (OPEX) and increasing the network lifetime of emerging wireless communication technologies by eliminating the need for frequent battery replacing or recharging of wireless devices. Among various ambient energy sources, the focus of this dissertation is on wireless power transfer (WPT) considering the unique characteristic of radio frequency (RF) signals; that is, they inherently carry both information and energy. A particularly interesting scenario arises when sources support simultaneous wireless information and power transfer (SWIPT) to provide a remote, controllable, and on-demand energy source. In this context, one of the promising deployment approaches is SWIPT-enabled cognitive radio networks (CRNs), which offer significant gains in terms of spectral and energy efficiencies. One of the practical scenarios of RF-powered CRN is deploying a number of distributed cognitive sensor nodes, equipped with RF EH modules, to sense a specific area and send the sensed data to an access point while coexisting with a primary licensed network. However, exploiting the full potentials of SWIPT-enabled CRNs is subject to carefully aligning the requirements of the EH unlicensed secondary receivers (SRs) with those of the legitimate primary receivers (PRs). In light of this, the first contribution of this thesis focuses on investigating the problem of beamforming for the downlink of multi-user multiple-input single-output (MU-MISO) CRNs. With the objective of minimising the transmission power of the secondary base station (SBS), optimal and suboptimal solutions for the formulated optimisation problem are provided by jointly optimising the transmit beamforming vector at the SBS and adjusting the parameters of the energy harvesters at the SRs. It is shown that the obtained solutions are efficient in meeting the EH and quality-of-service (QoS) requirements of the SRs and the levels of interference accepted by the PRs.
Apart from SWIPT-enabled CRNs, relay-assisted SWIPT networks are envisioned to be a promising framework offering extended coverage, diversity gains, and enhanced energy efficiency. In this case, the relay network itself can benefit from the relayed transmissions in terms of saving energy, and the harvested energy can be used to charge relay nodes and extend their lifetime as compensation for their role of data forwarding. Nonetheless, a concrete performance analysis on the impact of the involved system parameters such as, the energy conversion efficiency and the location of the EH relay terminal, on the trade-off between the achievable information transfer efficiency and the harvested energy level is crucial for the successful implementation of SWIPT in this context. This inspired the research work in the next two contributions with the main focus on developing novel comprehensive analytical frameworks for the investigation and evaluation of SWIPT relaying systems. Specifically, the second contribution is dedicated to examining the application of noncoherent modulation, which is recognised as an energy efficient modulation scheme for SWIPT, due to its ability to eliminate the need of instantaneous channel state information (CSI) estimation/tracking. Through adopting a moments-based approach, novel expressions are derived for the outage probability, achievable throughput, and average symbol error rate (ASER) of dual-hop SWIPT relaying systems. Furthermore, new asymptotic analytical results are derived for the high SNR regime and are then utilised to analytically quantify the achievable diversity order. The proposed mathematical tools are demonstrated to be an accurate and efficient means by which one can conduct a thorough analysis on the system performance without the burden of Monte Carlo simulations. Finally, the third contribution focuses on SWIPT relaying systems oper