Performance Analysis of Cooperative Quadrature Spatial Modulation System With Hybrid Decode-Amplify-Forward Relaying Protocol

This paper introduces the cooperative quadrature spatial modulation (CQSM) system with hybrid decode-amplify-forward (HDAF) relaying protocol. Compered with the traditional CQSM system which only uses amplify-and-forward (AF) protocol and decode-and-forward (DF) protocol, the system has enhanced the spectral efficiency and the performance of the average bit error probability (ABEP). In the proposed CQSM system, the information bit selects the relay to forward the information, while the relay index carries the information. At the relay, the amplify-and-forward (AF) protocol and the adaptive decode-and-forward (ADF) protocol are combined. The relay uses the AF protocol instead of remaining silent in the ADF protocol when the relay decodes signal incorrectly. Meanwhile, the closed-form expression of the ABEP for the proposed scheme is derived in detail. Furthermore, Monte Carlo simulation results verify the correctness of the theoretical ABEP derivation and the superiority of the proposed CQSM system with HDAF protocol over other existing schemes in terms of ABEP.