Performance Analysis of Transmit Diversity Systems with Multiple Antenna Replacement

Ki-Hong PARK
Hong-Chuan YANG
Young-Chai KO

IEICE TRANSACTIONS on Communications   Vol.E91-B    No.10    pp.3281-3287
Publication Date: 2008/10/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.10.3281
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
diversity techniques,  switched diversity,  space-time block coding,  order statistics,  Rayleigh fading channels,  

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Transmit diversity systems based on orthogonal space-time block coding (OSTBC) usually suffer from rate loss and power spreading. Proper antenna selection scheme can help to more effectively utilize the transmit antennas and transmission power in such systems. In this paper, we propose a new antenna selection scheme for such systems based on the idea of antenna switching. In particular, targeting at reducing the number of pilot channels and RF chains, the transmitter now replaces the antennas with the lowest received SNR with unused ones if the output SNR of space time decoder at the receiver is below a certain threshold. With this new scheme, not only the number of pilot channels and RF chains to be implemented is decreased, the average amount of feedback information is also reduced. To analyze the performance of this scheme, we derive the exact integral closed form for the probability density function (PDF) of the received SNR. We show through numerical examples that the proposed scheme offers better performance than traditional OSTBC systems using all available transmitting antennas, with a small amount of feedback information. We also examine the effect of different antenna configuration and feedback delay.