Impact of NLPA and imperfect CSI on ASER performance of QAM schemes for two-way 3P-ANC multiple-relay network

In this study, we examine the performance of higher-order quadrature amplitude modulation (QAM) schemes in a two-way multiple-relay network. This network employs three-phase analog network coding and an opportunistic relay selection algorithm while dealing with imperfect channel state information (CSI) and nonlinear power amplifiers (NLPA). Specifically, we derive lower-bound expressions for general-order rectangular QAM, hexagonal QAM, and cross QAM schemes. We assess performance over Nakagami-m fading channels with integer-valued fading parameters that are independently and non-identically distributed. Our analysis focuses on variable-gain amplify-and-forward relaying combined with maximal ratio combining receivers. To calculate closed-form average symbol error rate (ASER) expressions, we utilize a well-established approach based on cumulative distribution functions. We validate the accuracy of our derived expressions by comparing them to results obtained through Monte Carlo simulations. Furthermore, we investigate how fading parameters, the number of relay nodes, imperfect CSI, and NLPA affect the network’s performance.