On Impact of Imperfect CSI Over Hexagonal QAM for TAS/MRC-MIMO Cooperative Relay Network

In this letter, we investigate the effect of imperfect channel state information (CSI) on quadrature amplitude modulation (QAM) schemes for a multi-input and multi-output (MIMO) variable gain non-regenerative cooperative network over the generalized Nakagami-m fading channel. Energy-efficient and standardized transmit antenna selection strategy is employed, to evaluate the system performance by considering the antenna link, which maximizes the received signal power. Framework for the upper-bound outage probability (OP), asymptotic OP and the average symbol error rate for hexagonal QAM, rectangular QAM, and 32-cross QAM are provided. Useful insights are drawn from comparative ASER analysis of various QAM schemes by considering the impact of both the fading parameter and the imperfect CSI for MIMO channels. Finally, the derived analytical results are validated through Monte-Carlo simulations.