Dr Seiamak Vahid

Senior Research Fellow
PhD in communications


In the fifth and beyond (5G/B5G) communication, wireless networks are evolved towards offering various services of different use cases and, therefore, need to span a wide range of requirements. While different services will be supported at the same time, radio resource management needs to consider the different requirements. In addition, as wireless systems are capable to support multi-connectivity, radio resource allocation becomes more challenging. In this context, we introduce a many-to-many matching game, and develop a distributed radio resource allocation algorithm supporting multi-connectivity. Simulation results demonstrate that the proposed approach improves the QoS levels of UEs by up to 14.9% considering their service requirements.

Meng Lu, Bastiaan Wissingh, Daan Ravesteijn, Jarno Pinola, Seiamak Vahid (2022)5G Applications in the Transport Vertical

Road transport is an important industry sector in Europe, in terms of jobs, market size and international trade. Moreover, it is vital from economic, social and environmental perspectives, e.g. for safer, greener and more resilient services forpeople and goods, taking into account higher level connected and automated vehicles. The poster targets 5G applications in this vertical industry especially for improving utility, efficient processes, and sustainability. It defines specific vertical use cases and scenarios by using the 5G wireless mobile telecommunications technology. In addition, it investigates the technological validation of the trials of the transport industry and addresses business opportunities for future 5G applications.

A Prakash, F Eichhorn, O Keil, M Emmelmann, J Gutiérrez, N Maletic, M Scheide, M Ehrig, E Grass, Anna Brunström, Mohammad Rajiullah, Jonas Karlsson, Alexander Rabitsch, Karl-Johan Grinnemo, G Caso, C Griwodz, Ö Alay, M Klausen, I Koffmann, P Matzakos, F Kaltenberger, V Koumaras, C Sakkas, G Theodoropoulos, A Papaioannou, V Frascolla, T Metsch, S Vahid, D Triantafyllopoulou, R Yogaratnam, F Carrez, K Moessner, D Tsolkas, P Garrido, E Atxutegi, G Xilouris, M Christopoulou, H Koumaras, T Sarlas, T Anagnostopoulos, A Díaz Zayas, I González, P Merino, I Mesogiti, F Setaki, E Theodoropoulou, A Fornés, G Gardikis, D Lioprasitis, P Ginatzis, I Mertzanis, T Prokopidis, I Etxebarria, I Pretel, E Saiz (2022)Deliverable D6.3, In: G Gardikis (eds.), 5th Generation End-to-end Network, Experimentation, System Integration, and Showcasing (5GENESIS)

This deliverable presents the third and final cycle of trials and experimentation activities executed over 5GENESIS facilities. The document is the continuation of deliverables D6.1 and D6.2, in the sense that it captures tests carried out over the evolved infrastructures hosting 5GENESIS facilities following the methodology defined in the previous editions of this deliverable. The tests reported in this document focus on i) the final 5G infrastructure deployments that includes radio and core elements mostly in Stand-Alone (SA) deployment configurations based on commercial and open implementations, and ii) the various use cases/applications, some of them also involving field trials. Most of the tests described herein, especially the generic/lab ones are performed using the Open5GENESIS experimentation suite. 

Valerio Frascolla, Bismark Okyere, Shahid Mumtaz, Jonathan Rodriguez, Kazi Saidul Huq, Andreas Georgakopoulos, Evangelos Kosmatos, Aspa Skalidi, Panagiotis Demestichas, Thanasis Oikonomou, Dimitrios Kritharidis, Panagiotis Panagiotopoulos, Panteleimon-Konstantinos Chartsias, Benoit Miscopein, Antonio De Domenico, Rida El Chall, Jeremy Estavoyer, Keith Briggs, Seiamak Vahid, Marcin Filo, Klaus Moessner, Uwe Herzog, (2018)Breaking the Access Technologies Silos by Enhancing MAC and RRM in 5G+Networks, In: 2018 EUROPEAN CONFERENCE ON NETWORKS AND COMMUNICATIONS (EUCNC)8442850pp. 65-69 IEEE

The 5G network is on the verge of being deployed, as the first set of 5G features have just been standardized by 3GPP. Never the less several unsolved issues endanger an effective and profitable deployment of 5G systems, to address which this paper proposes some significant enhancements in the backhaul, at MAC, and at RRM layers. Leveraging on a new concept called extended Dynamic Spectrum Access (eDSA), novel algorithms and protocols are proposed, one of which is based on the Filter Bank Multicarrier (FBMC) technology. The results are mainly taken from the work of SPEED-5G, an EU-funded research project.

Ioannis Selinis, Konstantinos Katsaros, Seiamak Vahid, Rahim Tafazolli, (2020)An IEEE 802.11ax Interference-Aware MAC Queue, In: 2020 IEEE 31ST ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS (IEEE PIMRC) IEEE

The first wave of IEEE 802.11ax capable devices have already hit the market, aiming at enhancing the Quality of Experience (QoE) for the users in dense deployments, by enabling novel features to improve throughput and spectrum efficiency. One of these features is Spatial Reuse (SR) mechanism, which is introduced for coping with the exposed node problem. Under the SR operation, nodes belonging on different Basic Service Sets (BSSs) are allowed to initiate concurrent transmissions, utilising the spectrum resources and improving throughput. However, the main challenge for this enabling technology is the increased interference level that is introduced by the concurrent transmissions. Even though, there are a few algorithms available in the literature that study this issue for the IEEE 802.11ax, in this article we look into that issue from a different perspective. We propose an Interference-Aware scheduler for the Medium Access Control (MAC) queue based on the interference level observed and other characteristics that can be obtained from the channel and the inter-BSS frames. This paper considers only downlink traffic for the evaluation of the proposed scheme with simulation-based results showing a clear performance improvement of up to 34% against the legacy First-In First-Out (FIFO) MAC queue by introducing new policies and leave room for further exploration and enhancements.

Marcin Filo, Chuan Foh, Seiamak Vahid, Rahim Tafazolli (2020)Performance Analysis of Ultra-Dense Networks with Regularly Deployed Base Stations, In: IEEE Transactions on Wireless Communications Institute of Electrical and Electronics Engineers

The concept of Ultra Dense Networks (UDNs) is often seen as a key enabler of the next generation mobile networks. The massive number of BSs in UDNs represents a challenge in deployment, and there is a need to understand the performance behaviour and benefit of a network when BS locations are carefully selected. This can be of particular importance to the network operators who deploy their networks in large indoor open spaces such as exhibition halls, airports or train stations where locations of BSs often follow a regular pattern. In this paper we study performance of UDNs in downlink for regular network produced by careful BS site selection and compare to the irregular network with random BS placement. We first develop an analytical model to describe the performance of regular networks showing many similar performance behaviour to that of the irregular network widely studied in the literature. We also show the potential performance gain resulting from proper site selection. Our analysis further shows an interesting finding that even for over-densified regular networks, a nonnegligible system performance could be achieved.

V Sucasas, S Althunibat, A Radwan, H Marques, J Rodriguez, S Vahid, R Tafazolli, F Granelli (2015)Lightweight security against combined IE and SSDF attacks in cooperative spectrum sensing for cognitive radio networks, In: SECURITY AND COMMUNICATION NETWORKS8(18)pp. 3978-3994 WILEY-BLACKWELL
G Alnwaimi, S Vahid, K Moessner (2015)Dynamic Heterogeneous Learning Games for Opportunistic Access in LTE-Based Macro/Femtocell Deployments, In: IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS14(4)pp. 2294-2308 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
M Hasanpour, Shahin Shariat, Payam Barnaghi, SA Hoseinitabatabaei, Seiamak Vahid, Rahim Tafazolli (2017)Quantum Load Balancing in Ad Hoc Networks, In: Quantum Information Processing16(148) Springer Verlag

this paper presents a novel approach in targeting load balancing in ad hoc networks utilizing the properties of quantum game theory. This approach benefits from the instantaneous and information-less capability of entangled particles to synchronize the load balancing strategies in ad hoc networks. The Quantum Load Balancing (QLB) algorithm proposed by this work is implemented on top of OLSR as the baseline routing protocol; its performance is analyzed against the baseline OLSR, and considerable gain is reported regarding some of the main QoS metrics such as delay and jitter. Furthermore, it is shown that QLB algorithm supports a solid stability gain in terms of throughput which stands a proof of concept for the load-balancing properties of the proposed theory.

RH Tehrani, S Vahid, D Triantafyllopoulou, H Lee, K Moessner (2016)Licensed Spectrum Sharing Schemes for Mobile Operators: A Survey and Outlook, In: IEEE Communications Surveys and Tutorials18(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.

Haeyoung Lee, Y Ko, Seiamak Vahid, Klaus Moessner (2015)Practical Spectrum Aggregation for Secondary Networks with Imperfect Sensing, In: IEEE Transactions on Vehicular Technology65(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.

Ioannis Selinis, Konstantinos Katsaros, Seiamak Vahid, Rahim Tafazolli (2019)Damysus: A Practical IEEE 802.11ax BSS Color Aware Rate Control Algorithm, In: International Journal of Wireless Information Networkspp. 1-23 Springer Verlag

Institute of Electrical and Electronics Engineers (IEEE) 802.11ax Spatial Reuse (SR) is a new feature in the IEEE 802.11 family, aiming at improving the spectrum efficiency and the network performance in dense deployments. The main and perhaps the only SR technique in that amendment is the Basic Service Set (BSS) Color. It aims at increasing the number of concurrent transmissions in a specific area, based on a newly defined Overlapping BSS/Preamble-Detection threshold. In this paper, we overview the latest developments introduced in the IEEE 802.11ax for the SR and propose a rate control algorithm developed to exploit the BSS Color scheme. Our proposed algorithm, Damysus is specifically designed to function in dense environments where other off-the-shelf algorithms show poor performance. Simulation results in various dense scenarios, show a clear performance improvement of up to 113% gain in throughput over the well known MinstrelHT algorithm.

Ioannis Selinis, Konstantinos Katsaros, Marion Allayioti, Seiamak Vahid, Rahim Tafazolli (2018)The Race to 5G Era; LTE and Wi-Fi, In: IEEE Access6pp. 56598-56636 IEEE

We are on the brink of a new era for the wireless telecommunications, an era that will change the way that business is done. The fifth generation (5G) systems will be the first realization in this new digital era where various networks will be interconnected forming a unified system. With support for higher capacity as well as low-delay and machine-type communication services, the 5G networks will significantly improve performance over the current fourth generation (4G) systems and will also offer seamless connectivity to numerous devices by integrating different technologies, intelligence, and flexibility. In addition to ongoing 5G standardization activities and technologies under consideration in the Third Generation Partnership Project (3GPP), the Institute of Electrical and Electronic Engineers (IEEE) based technologies operating on unlicensed bands, will also be an integral part of a 5G eco-system. Along with the 3GPP-based cellular technology, IEEE standards and technologies are also evolving to keep pace with the user demands and new 5G services. In this article, we provide an overview of the evolution of the cellular and Wi-Fi standards over the last decade with particular focus on Medium Access Control (MAC) and Physical (PHY) layers, and highlight the ongoing activities in both camps driven by the 5G requirements and use-cases.

H Lee, S Vahid, K Moessner (2014)A survey of radio resource management for spectrum aggregation in LTE-advanced, In: IEEE Communications Surveys and Tutorials16(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.

Haeyoung Lee, Seiamak Vahid, Klaus Moessner (2019)Machine Learning based RATs Selection supporting Multi-Connectivity for Reliability, In: Proceedings of the 14th EAI International Conference on Cognitive Radio Oriented Wireless Networks (CrownCOM 2019) European Alliance for Innovation / Springer

While ultra-reliable and low latency communication (uRLLC) is expected to cater to emerging services requiring real-time control, such as factory automation and autonomous driving, the design of uRLLC of stringent requirements would be very challenging. Among novel solutions to satisfy uRLLC's requirements, interface diversity is widely regarded as an efficient enabler of ultra-reliable connectivity. When mobile de- vices are connected to multiple base stations (BSs) of different radio access technologies (RATs) and same data is transmitted via multiple links simultaneously, the transmission reliability can be improved. How- ever, duplicate transmission of same data causes an increase in the traffic loads, leading to radio resource shortage. Considering it, efficient config- uration of multi-connectivity (MC) for mobile devices is important. In this paper, the RAT selection scheme including efficient MC configura- tion is proposed. By adopting distributed reinforcement learning (RL), each device could learn the policy for efficient MC configuration and select appropriate RATs. Simulation results show that 20.8% reliabil- ity improvements over the single connectivity scheme is observed. Com- paring to the method to configure MC for devices all the time, 37.6% improvement is achieved at high traffic loads.

Dionysia Triantafyllopoulou, Seiamak Vahid, Klaus Moessner (2018)Co-Primary Spectrum Sharing in Uplink SC-FDMA Networks, In: 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.

Wenjuan Yu, Atta ul Quddus, Seiamak Vahid, Rahim Tafazolli (2018)Opportunistic spectrum access in support of ultra-reliable and low-latency communications, In: Proceedings of 2018 IEEE Global Communications Conference (GLOBECOM) Institute of Electrical and Electronics Engineers (IEEE)

This paper addresses the problem of opportunistic spectrum access in support of mission-critical ultra-reliable and low latency communications (URLLC). Considering the ability of supporting short packet transmissions in URLLC scenarios, a new capacity metric in finite blocklength regime is introduced as the traditional performance metrics such as ergodic capacity and outage capacity are no longer applicable. We focus on an opportunistic spectrum access system in which the secondary user (SU) opportunistically occupies the frequency resources of the primary user (PU) and transmits reliable short packets to its destination. An achievable rate maximization problem is then formulated for the SU in supporting URLLC services, subject to a probabilistic received-power constraint at the PU receiver and imperfect channel knowledge of the SU-PU link. To tackle this problem, an optimal power allocation policy is proposed. Closedform expressions are then derived for the maximum achievable rate in finite blocklength regime, the approximate transmission rate at high signal-to-noise ratios (SNRs) and the optimal average power. Numerical results validate the accuracy of the proposed closed-form expressions and further reveal the impact of channel estimation error, block error probability, finite blocklength and received-power constraint.

Ioannis Selinis, Konstantinos Katsaros, Seiamak Vahid, Rahim Tafazolli (2019)Eliminating the Use of IEEE 802.11 Acknowledgements; A Network Coding Approach, In: Proceedings of the 2019 IEEE Wireless Communications and Networking Conference (WCNC 2019) Institute of Electrical and Electronics Engineers (IEEE)
Haeyoung Lee, Seiamak Vahid, Klaus Moessner (2017)Traffic-aware Carrier Allocation with Aggregation for Load Balancing, In: 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.

Haeyoung Lee, Seiamak Vahid, Klaus Moessner (2018)Traffic-aware Resource allocation with aggregation in Heterogeneous Networks with WLANs, In: 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.

S Vahid (2015)Small Cells for 5G Mobile Networks, In: Fundamentals of 5G Mobile Networks(3) John Wiley & Sons

Jonathan Rodriguez. all data flowing between the targeted end user and the network. This attack exploits the unprotected user traffic in some part of the HeNB . For that reason, unprotected user data should never leave a secure domain inside ...

H Lee, S Vahid, K Moessner (2014)The Study on Spectrum/Channel Fragmentation from Dynamic Spectrum Aggregation in CRNs, In: 2014 EUROPEAN CONFERENCE ON NETWORKS AND COMMUNICATIONS (EUCNC)
Ioannis Selinis, Konstantinos Katsaros, Seiamak Vahid, Rahim Tafazolli (2018)Control OBSS/PD Sensitivity Threshold for IEEE 802.11ax BSS Color, In: 2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)pp. 1-7 Institute of Electrical and Electronics Engineers (IEEE)

IEEE 802.11ax Spatial Reuse (SR) is a new category in the IEEE 802.11 family, aiming at improving the spectrum efficiency and the network performance in dense deployments. The main and perhaps the only SR technique in that amendment is the Basic Service Set (BSS) Color. It aims at increasing the number of concurrent transmissions in a specific area, based on a newly defined Overlapping BSS/Preamble-Detection (OBSS/PD) threshold and the Received Signal Strength Indication (RSSI) from Overlapping BSSs (OBSSs). In this paper, we propose a Control OBSS/PD Sensitivity Threshold (COST) algorithm for adjusting OBSS/PD threshold based on the interference level and RSSI from the associated recipient(s). In contrast to the Dynamic Sensitivity Control (DSC) algorithm that was proposed for setting OBSS/PD, COST is fully aware of any changes in OBSSs and can be applied to any IEEE 802.11ax node. Simulation results in various scenarios, show a clear performance improvement of up to 57% gain in throughput over a conservative fixed OBSS/PD for the legacy BSS Color and DSC.

V Sucasas, A Radwan, H Marques, J Rodriguez, S Vahid, R Tafazolli (2015)Can We Apply Clustering in Fast Moving Objects?, In: S Mumtaz, J Rodriguez, M Katz, C Wang, A Nascimento (eds.), WIRELESS INTERNET (WICON 2014)146pp. 76-84
R Bassoli, VN Talooki, H Marques, J Rodriguez, S Vahid, R Tafazolli (2014)LT codes for video streaming in burst erasure channels: An energy analysis., In: ISCCpp. 1-4
H Lee, S Vahid, K Moessner (2012)Utility-based Dynamic Spectrum Aggregation algorithm in Cognitive Radio Networks, In: 2012 IEEE VEHICULAR TECHNOLOGY CONFERENCE (VTC FALL)
Ioannis Selinis, Konstantinos Katsaros, Seiamak Vahid, Rahim Tafazolli (2017)Exploiting the Capture Effect on DSC and BSS Color in Dense IEEE 802.11ax Deployments, In: Proceedings of the Workshop on ns-3 - 2017 WNS3pp. 47-54 Association for Computing Machinery (ACM)

Future wireless local area networks (WLANs) are expected to serve thousands of users in diverse environments. To address the new challenges that WLANs will face, and to overcome the limitations that previous IEEE standards introduced, a new IEEE 802.11 amendment is under development. IEEE 802.11ax aims to enhance spectrum efficiency in a dense deployment; hence system throughput improves. Dynamic Sensitivity Control (DSC) and BSS Color are the main schemes under consideration in IEEE 802.11ax for improving spectrum efficiency In this paper, we evaluate DSC and BSS Color schemes when physical layer capture (PLC) is modelled. PLC refers to the case that a receiver successfully decodes the stronger frame when collision occurs. It is shown, that PLC could potentially lead to fairness issues and higher throughput in specific cases. We study PLC in a small and large scale scenario, and show that PLC could also improve fairness in specific scenarios.

S Vahid (2015)SON Evolution for 5G Mobile Networks, In: Fundamentals of 5G Mobile Networks(10) John Wiley & Sons

Jonathan Rodriguez. all data flowing between the targeted end user and the network. This attack exploits the unprotected user traffic in some part of the HeNB . For that reason, unprotected user data should never leave a secure domain inside ...

K Moessner, S Vahid, R Tafazolli (2001)Terminal reconfigureability-the OPTiMA framework, In: Proc. Second Int 3G Mobile Communication Technologies Conf. (Conf. Publ. No. 477)pp. 241-246
H Lee, S Vahid, K Moessner (2014)A Sub-Optimal Channel Switching-Aware Spectrum Aggregation Approach for CRNs, In: 2014 9TH INTERNATIONAL CONFERENCE ON COGNITIVE RADIO ORIENTED WIRELESS NETWORKS AND COMMUNICATIONS (CROWNCOM)pp. 114-119
J Pérez-Romero, O Sallent, F Bouali, H Sarvanko, M Mustonen, M Matinmikko, H Lee, S Vahid, K Moessner (2012)A spectrum selection framework for Opportunistic Networks, In: 2012 Future Network and Mobile Summit, FutureNetw 2012pp. 1-9

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.

K Moessner, S Vahid, R Tafazolli (1999)Extension of the PNNI to support mobility management and handoffs in WATM networks based on CORBA, In: Proc. IEEE 49th Vehicular Technology Conf3pp. 2515-2519
V Sucasas, A Radwan, H Marques, J Rodriguez, S Vahid, R Tafazolli (2014)On the Efficiency of Merging Procedures in Hierarchical Mobile Cooperative Networks, In: A Jamalipour, DJ Deng (eds.), 2014 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)pp. 30-35
V Sucasas, A Radwan, H Marques, J Rodriguez, S Vahid, R Tafazolli (2014)How much overhead is required for stable group formation in VANETs?, In: 2014 IEEE 19TH INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD)pp. 21-25
Ioannis Selinis, Marcin Filo, Seiamak Vahid, Jonathan Rodriguez, Rahim Tafazolli (2017)Evaluation of the DSC algorithm and the BSS color scheme in dense cellular-like IEEE 802.11ax deployments, In: 2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)pp. 1641-1647 Institute of Electrical and Electronics Engineers (IEEE)

Coping with the extreme growth of the number of users is one of the main challenges for the future IEEE 802.11 networks. The high interference level, along with the conventional standardized carrier sensing approaches, will degrade the network performance. To tackle these challenges, the Dynamic Sensitivity Control (DSC) and the BSS Color scheme are considered in IEEE 802.11ax and IEEE 802.11ah, respectively. The main purpose of these schemes is to enhance the network throughput and improve the spectrum efficiency in dense networks. In this paper, we evaluate the DSC and the BSS Color scheme along with the PARTIAL-AID (PAID) feature introduced in IEEE 802.11ac, in terms of throughput and fairness. We also, exploit the performance when the aforementioned techniques are combined. The simulations show a significant gain in total throughput when these techniques are applied.

V Sucasas, A Radwan, H Marques, J Rodriguez, S Vahid, R Tafazolli (2014)A Cognitive Approach for Stable Cooperative Group formation in Mobile Environments, In: A Jamalipour, DJ Deng (eds.), 2014 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)pp. 3241-3245
H Lee, Y Ko, S Vahid, K Moessner (2014)Opportunistic Spectrum Aggregation for Cognitive Communications Under Collision Constraints, In: 2014 9TH INTERNATIONAL CONFERENCE ON COGNITIVE RADIO ORIENTED WIRELESS NETWORKS AND COMMUNICATIONS (CROWNCOM)pp. 7-12
R Bassoli, H Marques, J Rodriguez, S Vahid, R Tafazolli (2013)Network Coding for Vertical Handoffs Between LTE and IEEE 802.11n: An Energy Perspective., In: EW
G Alnwaimi, S Vahid, K Moessner (2015)Distributed Learning Game based Spectrum Sharing and Resource Selection for Femtocells, In: 2015 22ND INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT)pp. 331-337
R Bassoli, H Marques, A Radwan, J Rodriguez, S Vahid, R Tafazolli (2013)Energy analysis of network coding in hard vertical handovers, In: 2013 3rd International Conference on Communications and Information Technology, ICCIT 2013pp. 304-308

In future mobile networks different technologies will coexist and wireless devices with multiple interfaces will move in a heterogeneous scenario. The capability to connect to different access radio technologies opens the way to vertical handover mechanisms. Then, allowing vertical handovers with low losses and costs will be a main requirement of future mobile networks. In this paper, we apply batched sparse (BATS) codes on hard vertical handovers to avoid packet losses due to erasures. The theoretical analysis shows that energy consumption per bit increases while BATS codes are used. In particular, the energy consumption per bit inversely grows with the size of the finite field of the code. © 2013 IEEE.

MR Rai, S Vahid, K Moessner (2015)SINR based Topology Control for Multihop Wireless Networks with Fault Tolerance, In: 2015 IEEE 81ST VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING)
G Alnwaimi, T Zahir, S Vahid, K Moessner (2013)Machine Learning based Knowledge Acquisition on Spectrum Usage for LTE Femtocells, In: 2013 IEEE 78TH VEHICULAR TECHNOLOGY CONFERENCE (VTC FALL)
V Sucasas, A Radwan, H Marques, J Rodriguez, S Vahid, R Tafazolli (2013)On the energy efficiency of low-mobility subsystems in hierarchical ad hoc networks., In: CAMADpp. 48-52