Error probability for M-ary modulation using hybrid selection/maximal-ratio combining in Rayleigh fading

In this paper, we derive exact expressions for the symbol error probability (SEP) of hybrid selection/maximal-ratio combining wireless systems in multipath fading environments. We consider coherent detection of several types of M-ary modulation for the case of independent Rayleigh fading on each diversity branch with equal signal-to-noise ratio averaged over the fading. We use a virtual branch technique which transforms the ordered physical branches, which are necessarily dependent, into independent and identically distributed virtual branches thereby permitting the derivation of exact SEP expressions.