Unveiling the Importance of SIC in NOMA Systems—Part 1: State of the Art and Recent Findings

Zhiguo Ding,H Vincent Poor,Robert Schober

doi:10.1109/lcomm.2020.3012604

Abstract

The key idea of non-orthogonal multiple access (NOMA) is to serve multiple users simultaneously at the same time and frequency, which can result in excessive multiple-access interference. As a crucial component of NOMA systems, successive interference cancelation (SIC) is key to combating this multiple-access interference, and is the focus of this letter, where an overview of SIC decoding order selection schemes is provided. In particular, selecting the SIC decoding order based on the users' channel state information (CSI) and the users' quality of service (QoS), respectively, is discussed. The limitations of these two approaches are illustrated, and then a recently proposed scheme, termed hybrid SIC, which dynamically adapts the SIC decoding order is presented and shown to achieve a surprising performance improvement that cannot be realized by the conventional SIC decoding order selection schemes individually.

Highlights

A S A paradigm shift for the design of multiple access techniques, non-orthogonal multiple access (NOMA) encourages spectrum sharing among multiple users, instead of forcing them to individually occupy orthogonal resource blocks as in conventional orthogonal multiple access (OMA) [1]
As one of the most promising multiple access techniques, NOMA has been extensively studied under the 3rd Generation Partnership Project (3GPP) framework, from Release 14 in 2015 to Release 16 in 2019, where NOMA was formally adopted for downlink transmission in Release 15, termed Evolved Universal Terrestrial Radio Access (E-UTRA) [2]–[4]
Numerical Studies: In Fig. 2, the performance of NOMA with hybrid successive interference cancelation (SIC) is demonstrated by using computer simulations, where quality of service (QoS)- and channel state information (CSI)-based SIC are used as benchmark schemes

Summary

INTRODUCTION

A S A paradigm shift for the design of multiple access techniques, non-orthogonal multiple access (NOMA) encourages spectrum sharing among multiple users, instead of forcing them to individually occupy orthogonal resource blocks as in conventional orthogonal multiple access (OMA) [1]. Selecting the SIC decoding order based on the users’ channel state information (CSI) is considered first, since this is a straightforward choice and has been used since the invention of NOMA [6], [8]. Dynamically switching the SIC decoding order can achieve a surprising performance improvement that cannot be realized by the two conventional schemes. This improvement is illustrated in this paper, and the underlying reasons are explained in detail

NOMA USING CSI-BASED SIC DECODING ORDER

NOMA USING QOS-BASED SIC DECODING ORDER

NOMA USING HYBRID SIC WITH ADAPTIVE DECODING ORDER

NOMA With Hybrid SIC

The Performance of Hybrid SIC

CONCLUSION