Spatial Multiple Access (SMA): Enhancing performances of MIMO-NOMA systems

TL;DR

This paper introduces Spatial Multiple Access (SMA), a novel technique based on spatial modulation, which outperforms NOMA in error performance, sum rate, and complexity for MIMO systems.

Contribution

The paper proposes SMA as a new multiple access scheme using spatial modulation, providing analytical performance metrics and demonstrating superiority over NOMA.

Findings

SMA achieves lower bit error rate than NOMA.

SMA has higher ergodic sum rate than NOMA.

SMA offers lower implementation complexity.

Abstract

The error performance of the Non-Orthogonal Multiple Access (NOMA) technique suffers from the inter-user interference (IUI) although it is a promising technique for the future wireless systems in terms of the achievable sum rate. Hence, a multiple access technique design with limited IUI and competitive to NOMA in terms of spectral efficiency is essential. In this letter, we consider so-called spatial multiple access (SMA) which is based on applying the principle of spatial modulation (SM) through the different users' data streams, as a strong alternative to MIMO-NOMA systems. The analytical expressions of bit error probability (BEP), ergodic sum rate and outage probability are derived for the SMA. The derivations are validated via computer simulations. In addition, the comparison of the SMA system with NOMA is presented. The results reveal that SMA outperforms to the NOMA in terms of the all performance metrics (i.e., bit error rate (BER), outage probability and ergodic sum rate) besides it provides low implementation complexity.