Finite-SNR Diversity Multiplexing Tradeoff of SIMO Diversity Combining Schemes

Multiple antennas are widely used in modern high speed wireless data communication systems. Though multiple antennas provide diversity as well as multiplexing gain, there is a fundamental tradeoff between the two under slow fading channel conditions, that any coding scheme can achieve. This is captured in the diversity multiplexing tradeoff (DMT) framework at asymptotically high signal to noise ratios (SNR). The framework has been further generalized for the non-asymptotic i.e finite SNR case. In this paper we analyze the DMT for the rate-adaptive SIMO (single input multiple output) receive diversity schemes, namely SIMO-MRC (maximal-ratio combining), SIMO-SC (selection combining) and SIMO-EGC (equal gain combining). We obtain closed form expressions of the DMT at finite SNR. These expressions enable comparison of performance of the above schemes at finite SNR. The results of this comparative study are presented here.