Opportunistic beamforming and scheduling for OFDMA systems
2007 (English)In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 55, no 5, 941-952 p.Article in journal (Refereed) Published
Orthogonal frequency-division multiple access (OFDMA) is an attractive technique for exploiting multiuser diversity in the downlink of a cellular system. This paper addresses three problems in multiuser diversity for OFDMA systems. First, we propose a way to significantly reduce the amount of channel state information (CSI) feedback without sacrificing performance too much, by selective and adaptive feedback. Second, we propose a way to increase the cell throughput and fairness by appying an opportunistic beamforming scheme to orthogonal frequency-division multiplexing. This beamforming scheme increases the frequency fading rate, which increases the multiuser diversity effect. Thirdly, we deal with the issue of fairness and quality-of-service (QoS) in opportunistic systems by proposing a modified proportional fair (PF) scheduler for OFDMA. Key features in the scheduler are that it incorporates QoS classes into the PF scheduler and that it has a tunable fairness level. Extensive simulation results are presented to evaluate. the performance of the proposed schemes. The opportunistic beamforming scheme performed well in comparison with several other schemes. The modified PF scheduler was able to give users different QoS, based on their requirements, while still exploiting multiuser diversity.
Place, publisher, year, edition, pages
IEEE , 2007. Vol. 55, no 5, 941-952 p.
multiple antennas, multiuser diversity, OFDM, scheduling, wireless system design
IdentifiersURN: urn:nbn:se:kth:diva-34961DOI: 10.1109/TCOMM.2007.896082ISI: 000246634000015ScopusID: 2-s2.0-34249081685OAI: oai:DiVA.org:kth-34961DiVA: diva2:427177
60th IEEE Vehicular Technology Conference Los Angeles, CA, SEP 26-29, 2004
Correction in: IEEE Transactions On Communications, 2007, vol. 55, issue. 6, page. 1266, doi: 10.1109/TCOMM.2007.900972 2011-06-272011-06-172011-12-01Bibliographically approved