Spectrally Efficient M‐ary QAM Based Multi‐antenna Cooperative System over TWDP Fading Channel

To cater the ever-increasing demand of wireless high-speed data access and mobile users, one of the potential enablers toward the sustainable improved network capacity is the network densification at different layers of the radio access system. In this article, a possible solution to achieve a spectrally efficient, ultradense network (UDN) for cellular communication is analyzed. In particular, the performance of the generalized M-ary quadrature amplitude modulation (M-QAM) scheme for multiantenna cooperative decode-and-forward (DF) system over two-wave with diffuse power (TWDP) fading is presented. The TWDP fading is evaluated using the moment generating function (MGF) based approach on spectral efficient QAM transmission. In this article, novel closed-form expressions for the exact average symbol error rate (ASER) for the generalized rectangular-QAM (R-QAM) and square-QAM (S-QAM) schemes are presented. The obtained expressions are in the form of Appell's and Laureicella's confluent hypergeometric function which can be evaluated mathematically either in the series or the integral-form. Further, the asymptotic analysis is also presented for the considered system to get better insights into the system. The analytical results derived are corroborated by simulations to validate the accuracy of the analysis.