27 research outputs found

    Performance Model for MRC Receivers with Adaptive Modulation and Coding in Rayleigh Fading Correlated Channels with Imperfect CSIT

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    RTUWO Advances in Wireless and Optical Communications 2015 (RTUWO 2015). 5-6 Nov Riga, Latvia.This paper presents a performance model of the packet reception process in a wireless link with one antenna transmitter and a multiple-antenna maximum-ratio combining (MRC) receiver. The objective is to address the performance evaluation of multiple antenna systems enabled with adaptive modulation and coding (AMC). Two main assumptions are used: 1) Rayleigh fading correlated channels, and 2) imperfect (outdated) channel state information at the transmitter side (CSIT). The results presented here suggest that spatial correlation not always affects the performance of the MRC receiver: at low signal-to-noise ratio (SNR), correlation can improve performance rather than degrading it. By contrast, at high SNR, correlation is found to always degrade performance. At high SNR, correlation tends to worse the degrading effects of imperfect CSIT, particularly when the number of antennas increases. Imperfect CSIT causes errors in the assignment of MCSs, thus reducing throughput performance. These errors become more evident at high SNR, particularly when the values of branch correlation and the number of antennas increase

    Joint Beamforming, Terminal Scheduling, and Adaptive Modulation with Imperfect CSIT in Rayleigh Fading Correlated Channels with Co-channel Interference

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    The Second International Conference on Advances in Signal, Image and Video Processing - from Sensing to Applications (SIGNAL 2017). 21 to 25, May, 2017, 5Gsignalwave. Barcelona, Spain.—This paper presents a resource allocation algorithm for multi-user wireless networks affected by co-channel interference. The analysis considers a network with one base station (BS) that uses a multiple antenna transmitter (beamformer) to schedule (in a time-division manner) transmissions towards a set of J one-antenna terminals in the presence of K persistent interferers. The transmitter is assumed to employ MaximumRatio Combining (MRC) beamforming with spatially-correlated branches and channel envelopes modelled as Rayleigh-distributed processes. The BS has access to an imperfect (outdated) copy of the instantaneous Channel State Information (CSI) of each terminal. Based on this CSI at the transmitter side (CSIT), the BS proceeds to select (at each time interval or time-slot) the terminal with the highest channel strength for purposes of transmission. This imperfect CSIT is also used to calculate the coefficients of the beamformer that will be used to transmit information towards the scheduled terminal, as well as for selecting the most appropriate modulation format (threshold-based decision). In addition, the transmission towards each scheduled terminal is assumed to experience persistent co-channel interference that will degrade the quality of the information reception process. The main merits of this work are the following: 1) joint analysis of MRC-based beamforming, terminal scheduling based on maximum channel strength, and modulation assignment, and 2) joint modelling of the effects of spatial correlation, co-channel interference and imperfect CSIT. Results suggest that scheduling helps in rejecting co-channel interference and the degrading effects of imperfect CSIT. Spatial correlation could some times lead to better performance than the uncorrelated case, particularly in the low SNR (Signal-to-Noise Ratio) regime. Conversely, uncorrelated branches always outperform the correlated case in the high SNR regime. The use of higher numbers of antennas also improve performance of the system. However, spatial correlation tends to accumulate over the antenna array thus leading to a more noticeable performance degradation and more allocation errors due to the outdated CSIT assumption.info:eu-repo/semantics/publishedVersio

    5G green cellular networks considering power allocation schemes

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    It is important to assess the effect of transmit power allocation schemes on the energy consumption on random cellular networks. The energy efficiency of 5G green cellular networks with average and water-filling power allocation schemes is studied in this paper. Based on the proposed interference and achievable rate model, an energy efficiency model is proposed for MIMO random cellular networks. Furthermore, the energy efficiency with average and water-filling power allocation schemes are presented, respectively. Numerical results indicate that the maximum limits of energy efficiency are always there for MIMO random cellular networks with different intensity ratios of mobile stations (MSs) to base stations (BSs) and channel conditions. Compared with the average power allocation scheme, the water-filling scheme is shown to improve the energy efficiency of MIMO random cellular networks when channel state information (CSI) is attainable for both transmitters and receivers.Comment: 14 pages, 7 figure

    Performance analysis of diversity wireless systems

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    Ph.DDOCTOR OF PHILOSOPH

    Spatial Modulation for Generalized MIMO:Challenges, Opportunities, and Implementation

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    A key challenge of future mobile communication research is to strike an attractive compromise between wireless network's area spectral efficiency and energy efficiency. This necessitates a clean-slate approach to wireless system design, embracing the rich body of existing knowledge, especially on multiple-input-multiple-output (MIMO) technologies. This motivates the proposal of an emerging wireless communications concept conceived for single-radio-frequency (RF) large-scale MIMO communications, which is termed as SM. The concept of SM has established itself as a beneficial transmission paradigm, subsuming numerous members of the MIMO system family. The research of SM has reached sufficient maturity to motivate its comparison to state-of-the-art MIMO communications, as well as to inspire its application to other emerging wireless systems such as relay-aided, cooperative, small-cell, optical wireless, and power-efficient communications. Furthermore, it has received sufficient research attention to be implemented in testbeds, and it holds the promise of stimulating further vigorous interdisciplinary research in the years to come. This tutorial paper is intended to offer a comprehensive state-of-the-art survey on SM-MIMO research, to provide a critical appraisal of its potential advantages, and to promote the discussion of its beneficial application areas and their research challenges leading to the analysis of the technological issues associated with the implementation of SM-MIMO. The paper is concluded with the description of the world's first experimental activities in this vibrant research field

    MIMO Systems

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    In recent years, it was realized that the MIMO communication systems seems to be inevitable in accelerated evolution of high data rates applications due to their potential to dramatically increase the spectral efficiency and simultaneously sending individual information to the corresponding users in wireless systems. This book, intends to provide highlights of the current research topics in the field of MIMO system, to offer a snapshot of the recent advances and major issues faced today by the researchers in the MIMO related areas. The book is written by specialists working in universities and research centers all over the world to cover the fundamental principles and main advanced topics on high data rates wireless communications systems over MIMO channels. Moreover, the book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity

    Outage probability formulas for cellular networks (contributions for MIMO, CoMP and time reversal features)

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    L étude de dimensionnement d un réseau cellulaire est une phase de conception qui doit permettre de déterminer les performances d un système dans une configuration donnée. Elle inclut l étude de couverture et l analyse de trafic. De complexes simulations sont possibles pour connaître les paramètres de performances d un réseau mais seules les études analytiques fournissent des résultats rapides. Par ailleurs, pour faire face à la demande de hauts débits, à la rareté du spectre fréquentiel et à l impossibilité d émettre à de plus fortes puissances, de nouvelles techniques de transmissions sont apparues. Nous sommes ainsi passés d un système classique à une seule antenne à des systèmes à multiple antennes et même à des scénarios de coopération entre stations de base. Dans cette thèse, nous proposons des modèles analytiques pour l étude des performances, notamment en termes de probabilités de coupure, de ces évolutions des réseaux cellulaires. Dans une première phase, nous considérons des systèmes multicellulaires à une antenne émettrice et une antenne réceptrice (SISO). Nous proposons deux méthodes d étude de l impact conjoint de l affaiblissement de parcours, de l effet de masque et des évanouissements rapides. Nous étudions, par la suite, un système à large bande utilisant le retournement temporel comme technique de transmission. Dans une deuxième phase, nous considérons des systèmes multicellulaires à antennes multiple à l émission ou à la réception (MISO/MIMO) implémentant les schémas de diversité Alamouti et de combinaison par rapport maximal (MRC). Ensuite, nous considérons un système multicellulaire multi-utilisateurs à précodage de forçage à zéro (ZFBF).The implementation of cellular systems have aroused issues related to the design of cellular networks termed to as network dimensioning. It includes the coverage estimation and thetraffic analysis. Simple models and methods are required to reduce the time consumption of these two analysis. At the same time, the growing demand for higher data rates constrained by the scarcity of frequency spectrum, and the requirements in terms of power consumption reduction make the telecommunication community think about new transmission techniques moving from the classical single antenna systems to multiple antenna systems and even the newly envisaged cooperative systems. In this thesis, we provide analytical models to assess the performance of these different cellular network evolutions in terms of outage probabilities. In a first study, we consider multicellular single input single output (SISO) systems. First, we propose two accurate methods to study the joint impact of path-loss, shadowing and fast fading. This system has so far been studied either considering the only impact of path-loss and Rayleigh fading, or considering the same channel model as in our case but providing very complex outage probability expressions. Then, we provide an outage probability expression in a wideband communication context implementing the Time Reversal (TR) transmission technique considering the impact of fast fading. In a second study, we focus on multiple antenna systems. We study the performance of a Multiple Input Multiple Output (MIMO) system implementing a transmit and a receivediversity schemes namely the Alamouti code and the Maximum Ratio Combining (MRC).PARIS-Télécom ParisTech (751132302) / SudocSudocFranceF
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