| Simple BER Approximations for Generalized Selection Combining (GSC) over Rayleigh Fading Channels and its SNR Gap Properties
Ning Kong, Broadcom Corporation, San Diego CA 92128
Abstract
The paper presents two simple closed-form approximated BER expressions for GSC, where m diversity branches with the largest SNR are selected from L total available branches, over both iid and non-iid Rayleigh fading channels. They contain only inverse SNR raised to the diversity order and asymptotically accurate as SNR increases. When , the approximations are the same as the approximated BERs of MRC presented in [4]. The SNR gaps resulting from coherently combining different number branches can be easily derived from these approximations. It is found in this paper that not only does these SNR gaps increase monotonically with m as expected for a fixed L, but also when m is fixed it increases monotonically with L. In other words, a larger L provides not only a greater diversity gain but also a greater SNR gain. It is also found that the increasing rate of these gaps monotonically decreases with both m and L which means the gap saturates as m and L increases.
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