Quadrature Spatial Modulation for Cooperative MIMO 5G Wireless Networks

In this paper, quadrature spatial modulation (QSM) is used in a cooperative decode-and-forward (DF) diversity systems in order to enhance the overall reliability and energy efficiency. In particular, a multi-antenna source communicates with a single-antenna destination with the help of a multi-antenna DF relay in the presence of a direct link. To study the system performance, we derive a closed-form expression for the average pairwise error probability (P̅E̅P̅) over Rayleigh fading channels. A tight upper bounded average bit error rate is obtained using the P̅E̅P expression. Moreover, simple approximate expressions are obtained to get insights on the system diversity. Numerical results, which match with simulations, show that QSM offers about 3 dB gain over the conventional spatial modulation in DF relaying systems.