A Comprehensive Framework for Quadrature Spatial Modulation in Generalized Fading Scenarios

In this paper, we present a comprehensive framework for quadrature spatial modulation (QSM) in generalized fading channels. In particular, the performance analysis of QSM systems in the presence of imperfect channel knowledge and under correlated fading channels is presented. A simple and closed-form expression for the pairwise error probability (PEP) is provided. Based on the obtained PEP, a closed-form upper bound expression for the average bit error probability (BEP) is obtained. The analysis is unified in the sense that it is applicable for any fading channel once its envelope and phase distributions are available. As such, different generalized fading distribution models, namely, η-μ, κ-μ, and α-μ distributions, are considered. The obtained results clearly show the influence of the fading parameters on the average BEP. In the case of the α-μ fading channels, increasing α has larger negative impact on the average BEP compared with increasing μ. For the κ-μ channels, increasing μ results in increasing the average BEP dramatically when compared with increasing κ. In the same context, in η-μ fading channels, as μ increases the average BEP degrades whereas increasing η slightly improves the average BEP. In addition, it is demonstrated that transmit-antenna correlation significantly deteriorate the average BEP when compared with receive-antenna correlation.