Symbol Error Rate of Rectangular QAM with Best-Relay Selection in Cooperative Systems over Rayleigh Fading Channels

An analytical expression for a lower bound of average symbol error rate (ASER) for Amplify and Forward cooperative systems with best-relay selection over Rayleigh fading channels is derived for general order rectangular quadrature amplitude modulation (QAM). A comparison of numerical values of the derived lower bound with Monte Carlo simulation results suggests that the obtained bound is suitable for less number of relays. Numerically evaluated ASER results are plotted and the effect of system parameters on the ASER is studied.