Comments on Downlink Non-Orthogonal Multiple Access: Relative Gain Subject to Near Sum-Rate Optimality

TL;DR

This paper analyzes the relative performance gain of non-orthogonal multiple access in a two-user downlink scenario near sum-rate optimality, providing explicit insights into when non-orthogonal methods outperform traditional orthogonal techniques.

Contribution

It offers a simple, explicit characterization of the relative gain of non-orthogonal over orthogonal transmission near sum-rate optimality in the two-user broadcast channel.

Findings

Explicit gain characterization under sum-rate near-optimality

Non-orthogonal access can significantly outperform orthogonal methods in certain conditions

Insights applicable to next-generation wireless network design

Abstract

Non-orthogonal access techniques have recently gained renewed interest in the context of next generation wireless networks. As the relative gain, with respect to traditionally employed orthogonal-access techniques depends on many factors, it is of interest to obtain insights by considering the simplest scenario, the two-user downlink (broadcast) channel where all nodes are equipped with a single antenna. Further, we focus on rate pairs that are in the vicinity of sum-rate optimalilty with respect to the capacity region of the broadcast channel. A simple and explicit characterization of the relative gain of non-orthogonal transmission with respect to orthogonal transmission is obtained under these conditions as an immediate consequence of the capacity regions of the two.