Performance of Cooperative SM-Aided Multiple Access Scheme with DF Relaying Protocol

Spatial modulation (SM) is a promising approach that has been introduced as an alternative to classical multiple-input multiple-output (MIMO) spatial multiplexing techniques with the hardware complexity reduction of those in mind, and is envisioned as a component in future 5G and beyond systems. Cooperative communications, on the other hand, provides additional diversity gains and high data rates while improving coverage. Combining the advantages of SM and cooperative communications would then further improve efficiency, without inducing a significant complexity. In this paper, a novel SM cooperative system with decode-and-forward (DF) protocol is proposed to ensure a viable balance between the system performance metrics: the transmission data rate and average bit error rate (BER). The system architecture and the corresponding signal processing with optimal detector (OD) for the cooperative SM system are presented in the presence of a direct communication link and multiple transmit/receive antennas at both the source (S), and the destination (D). Code division multiple access (CDMA) technique is also incorporated in the proposed solution to address multiple access contexts arising from very high data rate communications and involvement of multiple relays, respectively.