Ergodic Rate Analysis of Massive Spatial Modulation MIMO System With NOMA in Cooperative Relay Networks

In this article, by introducing nonorthogonal multiple access (NOMA) scheme into the massive spatial modulation (SM) MIMO in cooperative relay networks, a massive cooperative NOMA-aided SM (NOMA-SM) system is presented. The ergodic rate performance of uplink massive cooperative NOMA-SM with finite alphabet inputs is investigated over Rayleigh fading channels. According to the performance analysis, the mutual information between the SM signals transmitted by users and the signal received at the base station (BS) is derived. Based on this, the theoretical lower bound and tight approximation of the ergodic rates are deduced for performance evaluation. With the aforementioned results, simple expressions of the ergodic rates are derived for the system with single-antenna relay, which can simplify the calculation of theoretical ergodic rate. Besides, when the number of receive antennas at the BS is very large, the asymptotic ergodic rate analysis is presented for massive cooperative NOMA-SM system, and the corresponding asymptotic lower bounds of the ergodic rate are derived. Simulation results indicate that the presented theoretical analysis is valid and can match the corresponding simulation well. Thus, the ergodic rate performance can be well assessed in theory.