44 research outputs found

    Cooperative Radio Communications for Green Smart Environments

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    The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: ‱ Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments‱ Measurements, characterization, and modelling of radio channels beyond 4G networks‱ Key issues in Vehicle (V2X) communication‱ Wireless Body Area Networks, including specific Radio Channel Models for WBANs‱ Energy efficiency and resource management enhancements in Radio Access Networks‱ Definitions and models for the virtualised and cloud RAN architectures‱ Advances on feasible indoor localization and tracking techniques‱ Recent findings and innovations in antenna systems for communications‱ Physical Layer Network Coding for next generation wireless systems‱ Methods and techniques for MIMO Over the Air (OTA) testin

    Device-to-Device Communication and Multihop Transmission for Future Cellular Networks

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    The next generation wireless networks i.e. 5G aim to provide multi-Gbps data traffic, in order to satisfy the increasing demand for high-definition video, among other high data rate services, as well as the exponential growth in mobile subscribers. To achieve this dramatic increase in data rates, current research is focused on improving the capacity of current 4G network standards, based on Long Term Evolution (LTE), before radical changes are exploited which could include acquiring additional/new spectrum. The LTE network has a reuse factor of one; hence neighbouring cells/sectors use the same spectrum, therefore making the cell edge users vulnerable to inter-cell interference. In addition, wireless transmission is commonly hindered by fading and pathloss. In this direction, this thesis focuses on improving the performance of cell edge users in LTE and LTE-Advanced (LTE-A) networks by initially implementing a new Coordinated Multi-Point (CoMP) algorithm to mitigate cell edge user interference. Subsequently Device-to-Device (D2D) communication is investigated as the enabling technology for maximising Resource Block (RB) utilisation in current 4G and emerging 5G networks. It is demonstrated that the application, as an extension to the above, of novel power control algorithms, to reduce the required D2D TX power, and multihop transmission for relaying D2D traffic, can further enhance network performance. To be able to develop the aforementioned technologies and evaluate the performance of new algorithms in emerging network scenarios, a beyond-the-state-of-the-art LTE system-level simulator (SLS) was implemented. The new simulator includes Multiple-Input Multiple-Output (MIMO) antenna functionalities, comprehensive channel models (such as Wireless World initiative New Radio II i.e. WINNER II) and adaptive modulation and coding schemes to accurately emulate the LTE and LTE-A network standards. Additionally, a novel interference modelling scheme using the ‘wrap around’ technique was proposed and implemented that maintained the topology of flat surfaced maps, allowing for use with cell planning tools while obtaining accurate and timely results in the SLS compared to the few existing platforms. For the proposed CoMP algorithm, the adaptive beamforming technique was employed to reduce interference on the cell edge UEs by applying Coordinated Scheduling (CoSH) between cooperating cells. Simulation results show up to 2-fold improvement in terms of throughput, and also shows SINR gain for the cell edge UEs in the cooperating cells. Furthermore, D2D communication underlaying the LTE network (and future generation of wireless networks) was investigated. The technology exploits the proximity of users in a network to achieve higher data rates with maximum RB utilisation (as the technology reuses the cellular RB simultaneously), while taking some load off the Evolved Node B (eNB) i.e. by direct communication between User Equipment (UE). Simulation results show that the proximity and transmission power of D2D transmission yields high performance gains for a D2D receiver, which was demonstrated to be better than that of cellular UEs with better channel conditions or in close proximity to the eNB in the network. The impact of interference from the simultaneous transmission however impedes the achievable data rates of cellular UEs in the network, especially at the cell edge. Thus, a power control algorithm was proposed to mitigate the impact of interference in the hybrid network (network consisting of both cellular and D2D UEs). It was implemented by setting a minimum SINR threshold so that the cellular UEs achieve a minimum performance, and equally a maximum SINR threshold to establish fairness for the D2D transmission as well. Simulation results show an increase in the cell edge throughput and notable improvement in the overall SINR distribution of UEs in the hybrid network. Additionally, multihop transmission for D2D UEs was investigated in the hybrid network: traditionally, the scheme is implemented to relay cellular traffic in a homogenous network. Contrary to most current studies where D2D UEs are employed to relay cellular traffic, the use of idle nodes to relay D2D traffic was implemented uniquely in this thesis. Simulation results show improvement in D2D receiver throughput with multihop transmission, which was significantly better than that of the same UEs performance with equivalent distance between the D2D pair when using single hop transmission

    Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

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    With the rapid development of marine activities, there has been an increasing number of maritime mobile terminals, as well as a growing demand for high-speed and ultra-reliable maritime communications to keep them connected. Traditionally, the maritime Internet of Things (IoT) is enabled by maritime satellites. However, satellites are seriously restricted by their high latency and relatively low data rate. As an alternative, shore & island-based base stations (BSs) can be built to extend the coverage of terrestrial networks using fourth-generation (4G), fifth-generation (5G), and beyond 5G services. Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs. Despite of all these approaches, there are still open issues for an efficient maritime communication network (MCN). For example, due to the complicated electromagnetic propagation environment, the limited geometrically available BS sites, and rigorous service demands from mission-critical applications, conventional communication and networking theories and methods should be tailored for maritime scenarios. Towards this end, we provide a survey on the demand for maritime communications, the state-of-the-art MCNs, and key technologies for enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Future challenges in developing an environment-aware, service-driven, and integrated satellite-air-ground MCN to be smart enough to utilize external auxiliary information, e.g., sea state and atmosphere conditions, are also discussed

    Cooperative Radio Communications for Green Smart Environments

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    The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: ‱ Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments‱ Measurements, characterization, and modelling of radio channels beyond 4G networks‱ Key issues in Vehicle (V2X) communication‱ Wireless Body Area Networks, including specific Radio Channel Models for WBANs‱ Energy efficiency and resource management enhancements in Radio Access Networks‱ Definitions and models for the virtualised and cloud RAN architectures‱ Advances on feasible indoor localization and tracking techniques‱ Recent findings and innovations in antenna systems for communications‱ Physical Layer Network Coding for next generation wireless systems‱ Methods and techniques for MIMO Over the Air (OTA) testin

    Contribution Ă  l’étude des SystĂšmes Multi-Antennes pour les TĂ©lĂ©communications et les Radars

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    Habilitation Ă  diriger des recherchesEtude des SystĂšmes Multi-Antennes pour les TĂ©lĂ©communications et les RadarsCe mĂ©moire rĂ©sume un peu plus de 10 annĂ©es de recherche, depuis ma thĂšse (soutenue en dĂ©cembre 2002), jusqu’à aujourd’hui au dĂ©partement OSA (Ondes et SystĂšmes AssociĂ©s) du Laboratoire XLIM Ă  l’universitĂ© de Limoges, oĂč je suis maĂźtre de confĂ©rences depuis septembre 2005.Mes activitĂ©s de recherche s’intĂ©graient initialement dans le domaine de l’électromagnĂ©tisme et des antennes (antennes multifonctions intĂ©grĂ©es, rĂ©seaux d’antennes pour la formation de faisceau ou pour des applications de goniomĂ©trie) avec une connotation plus poussĂ©e sur les antennes miniatures. Par la suite, ce dernier axe de recherche s’est naturellement orientĂ© vers l’étude des systĂšmes multi-antennes (MIMO), permettant notamment de lutter contre les Ă©vanouissements du canal radio, qui reprĂ©sentait un challenge important en terme d’intĂ©gration au sein d’un terminal mobile par exemple. Cependant, pour ĂȘtre pleinement couvert, ce domaine d’études nĂ©cessite de prendre en considĂ©ration, non seulement les antennes, mais aussi le canal de propagation multitrajets, la mise en forme et les traitements numĂ©riques des signaux associĂ©s au systĂšme multi-antennes. C’est dans ce sens qu’une nouvelle Ă©quipe de recherche (« rĂ©seaux sans fil ») a Ă©tĂ© crĂ©Ă©e au sein du dĂ©partement OSA d’XLIM, et dont je suis responsable depuis 2006. Les axes de recherche abordĂ©s concernent donc de maniĂšre gĂ©nĂ©rale le vaste domaine des systĂšmes de transmissions multi-antennes pour les communications et les radars, ainsi que le sondage de canal. Ils s’appuient sur une forte partie expĂ©rimentale par la mise en Ɠuvre de bancs de mesures permettant la caractĂ©risation active d’algorithmes liĂ©s aux traitements multi-antennes (codages MIMO, formation de faisceau, imagerie radar, 
), en environnement maĂźtrisĂ© (chambre rĂ©verbĂ©rante Ă  brassage de mode, chambre anĂ©choĂŻde multicapteurs) et en environnement rĂ©el

    Improving Multicast Communications Over Wireless Mesh Networks

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    In wireless mesh networks (WMNs) the traditional approach to shortest path tree based multicasting is to cater for the needs of the poorest performingnode i.e. the maximum permitted multicast line rate is limited to the lowest line rate used by the individual Child nodes on a branch. In general, this meansfixing the line rate to its minimum value and fixing the transmit power to its maximum permitted value. This simplistic approach of applying a single multicast rate for all nodes in the multicast group results in a sub-optimal trade-off between the mean network throughput and coverage area that does not allow for high bandwidth multimedia applications to be supported. By relaxing this constraint and allowing multiple line rates to be used, the mean network throughput can be improved. This thesis presents two methods that aim to increase the mean network throughput through the use of multiple line rates by the forwarding nodes. This is achieved by identifying the Child nodes responsible for reducing the multicast group rate. The first method identifies specific locations for the placement of relay nodes which allows for higher multicast branch line rates to be used. The second method uses a power control algorithm to tune the transmit power to allow for higher multicast branch line rates. The use of power control also helps to reduce the interference caused to neighbouring nodes.Through extensive computer simulation it can be shown that these two methods can lead to a four-fold gain in the mean network throughput undertypical WMN operating conditions compared with the single line rate case
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