48 research outputs found
Implementation of New Multiple Access Technique Encoder for 5G Wireless Telecomunication Networks
RĂSUMĂ Les exigences de la connectivitĂ© mobile massive de diffĂ©rents appareils et de diverses applications dĂ©terminent les besoins des prochaines gĂ©nĂ©rations de technologies mobiles (5G) afin de surmonter les demandes futures. L'expansion significative de la connectivitĂ© et de la densitĂ© du trafic caractĂ©risent les besoins de la cinquiĂšme gĂ©nĂ©ration de rĂ©seaux mobiles. Par consĂ©quent, pour la 5G, il est nĂ©cessaire d'avoir une densitĂ© de connectivitĂ© beaucoup plus Ă©levĂ©e et une plus grande
portée de mobilité, un débit beaucoup plus élevé et une latence beaucoup plus faible. En raison de l'exigence d'une connectivité massive, de nombreuses nouvelles technologies
doivent ĂȘtre amĂ©liorĂ©es: le codage des canaux, la technique d'accĂšs multiple, la modulation et la diversitĂ©, etc. Par consĂ©quent, compte tenu de l'environnement 5G, surcoĂ»t de signalisation et de la latence devrait ĂȘtre pris en compte [1]. En outre, l'application de la virtualisation des accĂšs sans fil (WAV) devrait Ă©galement ĂȘtre considĂ©rĂ©e et, par consĂ©quent, il est Ă©galement nĂ©cessaire de concevoir la plate-forme matĂ©rielle prenant en charge les nouvelles normes pour la mise en Ćuvre des Ă©metteurs-rĂ©cepteurs virtuels. L'une des nouvelles technologies possibles pour la 5G est l'accĂšs multiple pour amĂ©liorer
le débit. Par conséquent, au lieu d'OFDMA utilisé dans la norme LTE (4G), l'application d'une nouvelle technique d'accÚs multiple appelée Sparse Code Multiple Access (SCMA) est investiguée dans cette dissertation. SCMA est une nouvelle technique d'accÚs multiple non orthogonale du
domaine fréquentiel proposée pour améliorer l'efficacité spectrale de l'accÚs radio sans fil [2]. L'encodage SCMA est l'un des algorithmes les plus simples dans les techniques d'accÚs multiple qui offre l'opportunité d'expérimenter des méthodes génériques de mise en oeuvre. En outre, la nouvelle méthode d'accÚs multiple est supposée fournir un débit plus élevé. Le choix du codage
SCMA avec moins de complexitĂ© pourrait ĂȘtre une approche appropriĂ©e. La cible fixĂ©e pour cette recherche Ă©tait d'atteindre un dĂ©bit dâencodage de plus de 1 Gbps pour le codeur SCMA. Les implĂ©mentations de codage SCMA ont Ă©tĂ© effectuĂ©es Ă la fois en logiciel et en matĂ©riel
pour permettre de les comparer. Les implémentations logicielles ont été développées avec le langage de programmation C. Parmi plusieurs conceptions, la performance a été améliorée en utilisant différentes méthodes pour augmenter le parallélisme, diminuer la complexité de calcul et par conséquent le temps de traitement.----------ABSTRACT The demands of massive mobile connectivity of different devices and diverse applications
at the same time set requirments for next generations of mobile technology (5G). The significant expansion of connectivity and traffic density characterize the requirements of fifth generation mobile. Therefore, in 5G, there is a need to have much higher connectivity density, higher mobility ranges, much higher throughput, and much lower latency. In pursuance of the requirement of massive connectivity, numerous technologies must be
improved: channel coding, multiple access technique, modulation and diversity, etc. For instance,
with 5G, the cost of signaling overhead and latency should be taken into account [1]. Besides, applying wireless access virtualization (WAV) should be considered and there is also a need to have effective implementations supporting novel virtual transceiver. One of the possible new technologies for 5G is exploiting multiple access techniques to improve throughput. Therefore, instead of OFDMA in LTE (4G), applying a new multiple access
technique called Sparse Code Multiple Access (SCMA) is an approach considered in this dissertation. SCMA is a new frequency domain non-orthogonal multiple access technique proposed to improve spectral efficiency of wireless radio access [2]. SCMA encoding is one of the simplest
multiple access technique that offers an opportunity to experiment generic implementation methods. In addition, the new multiple access method is supposed to provide higher throughput, thus choosing SCMA encoding with less complexity could be an appropriate approach. The target
with SCMA was to achieve an encoding throughput of more that 1Gbps. SCMA encoding implementations were done both in software and hardware to allow comparing them. The software implementations were developed with the C programing language. Among several designs, the performance was improved by using different methods to increase
parallelism, decrease the computational complexity and consequently the processing time. The best achieved results with software implementations offer a 3.59 Gbps throughput, which is 3.5 times more that the target. For hardware implementation, high level synthesis was experimented. In order to do that, the C based functions and testbenches which were developed for software implementations, were
used as inputs to Vivado HLS
Performance evaluation of cross-layer energy-efficient transmit antenna selection for spatial multiplexing systems
Abstract Multiple-input multiple-output (MIMO) and cognitive radio (CR) are key techniques for present and future high-speed wireless technologies. On the other hand, there are rising energy costs and greenhouse emissions associated with the provision of high-speed wireless communications. Consequently, the design of high-speed energy efficient systems is paramount for next-generation wireless systems. This thesis studies energy-efficient antenna selection for spatial multiplexing multiple-antenna systems from a cross-layer perspective, contrary to the norm, where physical-layer energy efficiency metrics are optimized. The enhanced system performance achieved by cross-layer designs in wireless networks motivates this research. The aim of the thesis is to propose and analyze novel cross-layer energy-efficient transmit antenna selection schemes that enhance energy efficiency and system performance - with regard to throughput, transmission latency, packet error rate and receiver buffer requirements. Firstly, this thesis derives the analytical expression for data link throughput for point-to-point spatial multiplexing multiple-antenna systems - which include MIMO and underlay CR MIMO systems - equipped with linear receivers with N-process stop-and-wait (N-SAW) as the automatic repeat request (ARQ) protocol. The performance of cross-layer transmit antenna selection, which maximizes the derived throughput metric, is then analyzed. The impact of packet size, number of SAW processes and the stalling of packets inside the receiver reordering buffer is considered in the investigation. The results show that the cross-layer approach, which takes into account system characteristics at both the data link and physical layers, has superior performance in comparison with the conventional physical-layer approach, which optimizes capacity. Secondly, this thesis proposes a cross-layer energy efficiency metric, based on the derived system throughput. Energy-efficient transmit antenna selection for spatial multiplexing MIMO systems, which maximizes the proposed cross-layer energy efficiency metric, by jointly optimizing the transmit antenna subset and transmit power, subject to spectral efficiency and transmit power constraints, is then introduced and analyzed. Additionally, adaptive modulation is incorporated into the proposed cross-layer scheme to enhance system performance. Cross-layer energyefficient transmit antenna selection for underlay CR MIMO systems, where interference constraints now come into play, is then considered. Lastly, this thesis develops novel reduced complexity versions of the proposed cross-layer energyefficient transmit antenna selection schemes - along with detailed complexity analysis - which shows that the proposed cross-layer approach attains significant energy efficiency and performance gains at affordable computational complexity
Scaling up virtual MIMO systems
Multiple-input multiple-output (MIMO) systems are a mature technology that has been incorporated
into current wireless broadband standards to improve the channel capacity and link
reliability. Nevertheless, due to the continuous increasing demand for wireless data traffic new
strategies are to be adopted. Very large MIMO antenna arrays represents a paradigm shift in
terms of theory and implementation, where the use of tens or hundreds of antennas provides
significant improvements in throughput and radiated energy efficiency compared to single antennas
setups. Since design constraints limit the number of usable antennas, virtual systems can
be seen as a promising technique due to their ability to mimic and exploit the gains of multi-antenna
systems by means of wireless cooperation. Considering these arguments, in this work,
energy efficient coding and network design for large virtual MIMO systems are presented.
Firstly, a cooperative virtual MIMO (V-MIMO) system that uses a large multi-antenna transmitter
and implements compress-and-forward (CF) relay cooperation is investigated. Since
constructing a reliable codebook is the most computationally complex task performed by the
relay nodes in CF cooperation, reduced complexity quantisation techniques are introduced. The
analysis is focused on the block error probability (BLER) and the computational complexity for
the uniform scalar quantiser (U-SQ) and the Lloyd-Max algorithm (LM-SQ). Numerical results
show that the LM-SQ is simpler to design and can achieve a BLER performance comparable to
the optimal vector quantiser. Furthermore, due to its low complexity, U-SQ could be consider
particularly suitable for very large wireless systems.
Even though very large MIMO systems enhance the spectral efficiency of wireless networks,
this comes at the expense of linearly increasing the power consumption due to the use of multiple
radio frequency chains to support the antennas. Thus, the energy efficiency and throughput
of the cooperative V-MIMO system are analysed and the impact of the imperfect channel state
information (CSI) on the systemâs performance is studied. Finally, a power allocation algorithm
is implemented to reduce the total power consumption. Simulation results show that
wireless cooperation between users is more energy efficient than using a high modulation order
transmission and that the larger the number of transmit antennas the lower the impact of the
imperfect CSI on the systemâs performance.
Finally, the application of cooperative systems is extended to wireless self-backhauling heterogeneous
networks, where the decode-and-forward (DF) protocol is employed to provide a
cost-effective and reliable backhaul. The associated trade-offs for a heterogeneous network
with inhomogeneous user distributions are investigated through the use of sleeping strategies.
Three different policies for switching-off base stations are considered: random, load-based and
greedy algorithms. The probability of coverage for the random and load-based sleeping policies
is derived. Moreover, an energy efficient base station deployment and operation approach
is presented. Numerical results show that the average number of base stations required to support
the traffic load at peak-time can be reduced by using the greedy algorithm for base station
deployment and that highly clustered networks exhibit a smaller average serving distance and
thus, a better probability of coverage
A Survey on Applications of Cache-Aided NOMA
Contrary to orthogonal multiple-access (OMA), non-orthogonal multiple-access (NOMA) schemes can serve a pool of users without exploiting the scarce frequency or time domain resources. This is useful in meeting the future network requirements (5G and beyond systems), such as, low latency, massive connectivity, users' fairness, and high spectral efficiency. On the other hand, content caching restricts duplicate data transmission by storing popular contents in advance at the network edge which reduces data traffic. In this survey, we focus on cache-aided NOMA-based wireless networks which can reap the benefits of both cache and NOMA; switching to NOMA from OMA enables cache-aided networks to push additional files to content servers in parallel and improve the cache hit probability. Beginning with fundamentals of the cache-aided NOMA technology, we summarize the performance goals of cache-aided NOMA systems, present the associated design challenges, and categorize the recent related literature based on their application verticals. Concomitant standardization activities and open research challenges are highlighted as well
Cooperative Radio Communications for Green Smart Environments
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: âą Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environmentsâą Measurements, characterization, and modelling of radio channels beyond 4G networksâą Key issues in Vehicle (V2X) communicationâą Wireless Body Area Networks, including specific Radio Channel Models for WBANsâą Energy efficiency and resource management enhancements in Radio Access Networksâą Definitions and models for the virtualised and cloud RAN architecturesâą Advances on feasible indoor localization and tracking techniquesâą Recent findings and innovations in antenna systems for communicationsâą Physical Layer Network Coding for next generation wireless systemsâą Methods and techniques for MIMO Over the Air (OTA) testin
D3.2 First performance results for multi -node/multi -antenna transmission technologies
This deliverable describes the current results of the multi-node/multi-antenna technologies
investigated within METIS and analyses the interactions within and outside Work Package 3.
Furthermore, it identifies the most promising technologies based on the current state of
obtained results. This document provides a brief overview of the results in its first part. The second part, namely the Appendix, further details the results, describes the simulation
alignment efforts conducted in the Work Package and the interaction of the Test Cases. The
results described here show that the investigations conducted in Work Package 3
are maturing resulting in valuable innovative solutions for future 5G systems.Fantini. R.; Santos, A.; De Carvalho, E.; Rajatheva, N.; Popovski, P.; Baracca, P.; Aziz, D.... (2014). D3.2 First performance results for multi -node/multi -antenna transmission technologies. http://hdl.handle.net/10251/7675
Radio Communications
In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modiïŹed our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the ïŹeld of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks