Exploiting Multiple-Antenna Techniques for Non-Orthogonal Multiple Access

TL;DR

This paper develops a comprehensive framework for multiple-antenna NOMA systems, including design, analysis, and optimization, demonstrating significant performance improvements over traditional OMA in multiuser downlink scenarios.

Contribution

It introduces a new multi-antenna NOMA framework with joint optimization of key parameters and provides analytical expressions and guidelines for system design.

Findings

Closed-form expressions for average transmission rates.

Performance gains over traditional OMA.

Effective joint optimization scheme for system parameters.

Abstract

This paper aims to provide a comprehensive solution for the design, analysis, and optimization of a multiple-antenna non-orthogonal multiple access (NOMA) system for multiuser downlink communication with both time duplex division (TDD) and frequency duplex division (FDD) modes. First, we design a new framework for multiple-antenna NOMA, including user clustering, channel state information (CSI) acquisition, superposition coding, transmit beamforming, and successive interference cancellation (SIC). Then, we analyze the performance of the considered system, and derive exact closed-form expressions for average transmission rates in terms of transmit power, CSI accuracy, transmission mode, and channel conditions. For further enhancing the system performance, we optimize three key parameters, i.e., transmit power, feedback bits, and transmission mode. Especially, we propose a low-complexity joint optimization scheme, so as to fully exploit the potential of multiple-antenna techniques in NOMA. Moreover, through asymptotic analysis, we reveal the impact of system parameters on average transmission rates, and hence present some guidelines on the design of multiple-antenna NOMA. Finally, simulation results validate our theoretical analysis, and show that a substantial performance gain can be obtained over traditional orthogonal multiple access (OMA) technology under practical conditions.