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Issue No. 10 - Oct. (2013 vol. 12)
ISSN: 1536-1233
pp: 1907-1919
Alex Leith , Iowa State University, Ames
Mohamed-Slim Alouini , KAUST, Saudi Arabia
Dong In Kim , Sungkyunkwan University, Suwon
Xuemin Shen , University of Waterloo, Waterloo
Zhiqiang Wu , Wright State University, Dayton
In this paper, we study the sum-rate maximization algorithms for downlink and uplink orthogonal frequency division multiple access (OFDMA) systems under proportional-rate constraint (PRC) and minimum-rate constraint. We develop a low-complexity weighted channel signal-to-noise ratio (w-SNR)-based ranking scheme for user selection on each subchannel in OFDMA combined with waterfilling (WF) power allocation. Both offline and online optimization algorithms are developed to optimize the SNR weight vector to maximize the sum rate while satisfying several constraints, such as PRC. The offline weight optimization technique relies on the analytical throughput results developed in this paper, and the online weight adaptation method tracks the user rates and meets the PRC using a subgradient search. Furthermore, we introduce a novel SNR operating region test to enhance the multiuser diversity gain and the sum rate. The proposed schemes have a low complexity, which is linear to the numbers of users and subchannels. Simulation results verify the accuracy of the developed analytical rates and fairness formulas, and show that the proposed w-SNR schemes can achieve higher sum rates than several benchmark schemes that provide the PRC with either short-term or long-term fairness.
Signal to noise ratio, Resource management, Downlink, Vectors, Optimization, Mobile computing, Throughput, throughput maximization, OFDMA, proportional rate constraint (PRC), admission control, multiuser diversity

Z. Wu, X. Shen, D. I. Kim, M. Alouini and A. Leith, "Flexible Proportional-Rate Scheduling for OFDMA System," in IEEE Transactions on Mobile Computing, vol. 12, no. , pp. 1907-1919, 2013.
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