Closed form expression for the error performance of noncoherent M-ary orthogonal signals over multi-branch Rayleigh fading channels with arbitrary average fading powers

This letter presents a closed form expression for the average error performance of noncoherent M-ary orthogonal signals over nonidentically distributed Rayleigh fading channels with postdetection equal-gain diversity combining (EGC). The derived expression can be easily evaluated numerically, and is valid for the general case in which the received average fading powers over diversity branches are arbitrary and not required to be distinct. In addition, it reduces to some existing results in the literature as special cases