NOMA Versus Massive MIMO in Rayleigh Fading

TL;DR

This paper analytically and empirically compares NOMA and massive MIMO, demonstrating that massive MIMO consistently outperforms NOMA in Rayleigh fading channels with a relatively small number of antennas.

Contribution

It provides a theoretical proof that massive MIMO outperforms NOMA in Rayleigh fading, supported by simulations showing the crossover at 20-30 antennas.

Findings

Massive MIMO outperforms NOMA in Rayleigh fading channels.

The crossover point occurs with 20-30 antennas.

Massive MIMO's advantage is evident with fewer antennas than next-generation requirements.

Abstract

This paper compares the sum rates and rate regions achieved by power-domain NOMA (non-orthogonal multiple access) and standard massive MIMO (multiple-input multiple-output) techniques. We prove analytically that massive MIMO always outperforms NOMA in i.i.d.~Rayleigh fading channels, if a sufficient number of antennas are used at the base stations. The simulation results show that the crossing point occurs already when having 20-30 antennas, which is far less than what is considered for the next generation cellular networks.