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International Journal of Antennas and Propagation
Volume 2012, Article ID 717494, 9 pages
http://dx.doi.org/10.1155/2012/717494
Research Article

General Switch-and-Stay Combing for Space Diversity over Rayleigh Fading Channels

1Department of Communications Engineering, Yuan Ze University, Chungli 320, Taiwan
2Information and Communications Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan

Received 26 December 2011; Accepted 17 February 2012

Academic Editor: Tat Yeo

Copyright © 2012 Yawgeng A. Chau and Yao-Hua Chen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Three multibranch switch-and-stay combining (MSSC) schemes are analyzed for Rayleigh fading channels, where different decision statistics for antenna switching (i.e., switch statistic) are used. Let and denote the fading factor and the received baseband signal of a diversity branch, respectively. In contrast to the traditional MSSC that uses the faded signal-to-noise ratio (SNR) of diversity branches as the corresponding switch statistic, to enhance the receiver performance, , , and a new linear combination of a and are used as switch statistics of the three MSSC schemes, respectively. For performance evaluation, the bit error rate (BER) of BPSK is derived for the three MSSC schemes over both independent-and-identical distributed (i.i.d.) and independent-and-nonidentical distributed (i.n.d.) Rayleigh fading channels. To pursue optimal performance, the locally optimal switch threshold (ST) of each MSSC scheme is obtained for general i.n.d. fading channels. In addition, the locally optimal ST becomes the globally optimal ST for i.i.d. channels. Numerical results based on the analysis and simulations are presented. In contrast to the MSSC over i.i.d. fading channels, we will show that the performance of MSSC schemes can be improved by increasing the number of branches, if i.n.d. channels are considered.