A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond

TL;DR

This tutorial introduces Nonorthogonal Multiple Access (NOMA) as a promising solution to enhance spectral efficiency and connectivity in 5G networks, comparing it with traditional OMA and discussing implementation challenges.

Contribution

It provides a unified model for NOMA in various scenarios, including extensions to MIMO and cooperative communications, along with performance comparisons and open issues.

Findings

NOMA outperforms OMA in spectral efficiency and connectivity.

Numerical examples demonstrate NOMA's advantages over traditional methods.

Implementation challenges and open research issues are discussed.

Abstract

Today's wireless networks allocate radio resources to users based on the orthogonal multiple access (OMA) principle. However, as the number of users increases, OMA based approaches may not meet the stringent emerging requirements including very high spectral efficiency, very low latency, and massive device connectivity. Nonorthogonal multiple access (NOMA) principle emerges as a solution to improve the spectral efficiency while allowing some degree of multiple access interference at receivers. In this tutorial style paper, we target providing a unified model for NOMA, including uplink and downlink transmissions, along with the extensions tomultiple inputmultiple output and cooperative communication scenarios. Through numerical examples, we compare the performances of OMA and NOMA networks. Implementation aspects and open issues are also detailed.