ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Groupwise generalized selection diversity combining and its applications in wireless communication
MILCOM'09 Proceedings of the 28th IEEE conference on Military communications
MILCOM'09 Proceedings of the 28th IEEE conference on Military communications
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The paper presents two simple closed-form approximated BER expressions for GSC, where m diversity branches with the largest SNR are selected from L (1 ≤ m ≤ 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 m = L, the approximations are the same as the approximated BERs of MRC presented in [4]. The SNR gaps resulting from coherently combining a different number branches are easily derived from these approximations. It is found that not only does the gap increase monotonically with m as expected for a fixed L, but also, when m is fixed the gap, 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 the gap monotonically decreases with both m and L which means the gap saturates as m and L increases. Finally we prove that as L → ∞ (fading channel becomes AWGN), the gap approaches to 10logm which is exactly the gap for the AWGN channel.