Cooperative Relaying Using Space-Time Block Coded Non-orthogonal Multiple Access

Abstract

Non-orthogonal multiple access (NOMA) has attracted significant attention in the research community as a potential radio access technology for future wireless networks. In this work, we propose a two-phase cooperative decode-and-forward (DF) relaying scheme based on Alamouti (2 x 1 multiple-input single-output mode) space-time block-coded non-orthogonal multiple access (STBC-NOMA). Closed-form solutions for ergodic sum capacity and outage probability of the proposed scheme are analyzed over independent Rayleigh fading channels. Asymptotic approximations for ergodic sum capacity, outage probability, and outage sum capacity at the high signal-to-noise ratio regime are also provided. It has been pointed out that the proposed cooperative relaying system (CRS) using STBC-NOMA can attain significant performance gains compared to the conventional CRS using NOMA and the traditional DF relaying schemes. It is also demonstrated that the relay position between the transmitter and the receiver has a significant impact on the performance of the proposed protocol. In addition, the proximity between analytical and simulation results confirms the efficiency of the proposed protocol.