SER of M-QAM decode-and-forward multi-relay systems under generalized fading conditions

The present paper evaluates the performance of regenerative multi-relay dual-hop cooperative network systems over non-homogeneous scattering conditions, which characterize realistic radio propagation scenarios in both conventional and emerging wireless communication systems. The considered analysis assumes maximum-ratio-combining reception at the destination node which improves the overall system performance in both severe and moderate fading conditions. In this context, an exact closed-form analytic expression is derived for the end-to-end symbol-error-rate of M-ary quadrature amplitude modulation over independently and non-identically distributed η - μ fading channels. The derived analytic results are based on the moment-generating-function approach and are subsequently employed in developing useful insights on the corresponding system performance. To this end, it is shown that the performance of the considered system is affected substantially by the number of employed relays as well as by the values of the fading parameters η and μ, since the difference in both cases is even over an order of magnitude compared to conventional transmission.