On the diversity enhancement and power balancing of per-subcarrier transmit antenna selection in OFDM systems
KAUST DepartmentElectrical Engineering Program
Physical Sciences and Engineering (PSE) Division
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Communication Theory Lab
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AbstractIn this paper, we consider multicarrier systems with multiple transmit antennas under a power-balancing constraint. Applying transmit antenna selection and discrete rate-adaptive modulation using M-ary quadrature-amplitude modulation (QAM) according to the channel variation per subcarrier, we develop an optimal transmit antenna selection scheme in terms of the maximum spectral efficiency, where all the possible groupings for sending the same information-bearing signals in a group of subcarriers are searched, and the groups of subcarriers for providing the frequency diversity gain are formed. In addition, we propose a suboptimal method for reducing the computational complexity of the optimal method. The suboptimal scheme considers only the subcarriers under outage, and these subcarriers are sequentially combined until the required signal-to-noise ratio (SNR) is met. Numerical results show that the proposed suboptimal method with diversity combining outperforms the optimal antenna selection without diversity combining, as introduced in the work of Sandell and Coon, particularly for low-SNR regions, and offers the spectral efficiency close to the optimal method with diversity combining while maintaining lower complexity. © 2011 IEEE.
SponsorsManuscript received July 19, 2010; revised December 29, 2010 and March 22, 2011; accepted April 16, 2011. Date of publication April 25, 2011; date of current version June 20, 2011. This work was supported in part by the Ministry of Knowledge Economy, Korea, through the Information Technology Research Center Support Program supervised by the National Information Technology Industry Promotion Agency (NIPA) under Contract NIPA-2011-C1090-1011-0007 and by Qatar National Research Fund: a member of the Qatar Foundation for Education, Science, and Community Development. The review of this paper was coordinated by Dr. D. W. Matolak.