Opportunistic Access Schemes for Multiuser OFDM Wireless Networks

International audienc

Comparison Study of Resource Allocation Strategies for OFDM Multimedia Networks

Advanced MAC scheduling schemes provide efficient support of multimedia services in multiuser OFDM wireless networks. Designed in a cross layer approach, they opportunistically consider the channel state and are well adapted to the wireless multipath fading environment. These schedulers take advantage of time, frequency, and multiuser diversity. Thereby they maximize the global system throughput while ensuring the highest possible level of fairness. However their performances heavily depend on the bandwidth granularity (i.e., the number of elementary resource units) that is used in the resource allocation process. This paper presents and compares the main OFDM scheduling techniques. In particular it studies the influence of bandwidth granularity on the resource allocation strategies performances. The paper reveals that though bandwidth granularity has never been considered in former studies, it is of major importance for determining the application range of advanced OFDM scheduling techniques

Compensated Proportional Fair Scheduling in Multiuser OFDM Wireless Networks

International audienceIn wireless networks, providing a fair bandwidth allocation without too much reducing the system throughput is very challenging. Path loss attenuations induce unequal spectral efficiencies and in terms unequal throughtput for mobiles with different geographical positions. In the litterature, Proportional Fair (PF) is acknowledged as the reference scheduler in multiuser OFDM wireless networks. Opportunistically considering the channel state, PF is adapted to the wireless environment fighting the multipath fading negative effects. PF takes advantage of multiuser diversity and globally maximizes the throughput. Additionally, PF scheduling currently makes the best tradeoff between fairness and throughput maximization. However, severe fairness deficiencies appear when the mobiles experience unequal path loss. In this paper, we propose to solve this fairness issue with a modified PF scheme that introduces distance compensation factors. Simulation results show that this well-balanced resource allocation outperforms other existing scheduling schemes and jointly provides both high system throughput and high fairness

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 modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field 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