Symbol Error Rate of Decode-and-Forward Relaying in Two-Wave with Diffuse Power Fading Channels

We analyze the symbol error rate (SER) of selective decode-and-forward (DF) relaying for the practical case of independent but not necessarily identically distributed two-wave with diffuse power (TWDP) fading. We first derive new exact SER expressions with M-ary phase-shift keying and M-ary quadrature amplitude modulation. We then derive tight upper bounds on the exact SER in closed form to avoid the numerical integration involved in the exact results. Furthermore, we derive concise yet valuable expressions for the asymptotic SER, which characterizes the system behavior in the high signal-to-noise ratio (SNR) regime in terms of the diversity order and the coding gain. Based on the asymptotic SER, we confirm that TWDP fading parameters have no impact on the diversity order, but affect the coding gain. We also demonstrate that the contribution of the source-destination link to the SER is higher than that of the source-relay link or the relay-destination link. Our analytical results are valid for general operating scenarios with arbitrary average SNRs and distinct TWDP fading parameters in each hop.