Secrecy Sum Rate Optimization for Downlink MIMO Nonorthogonal Multiple Access Systems

• Published in: IEEE signal processing letters Vol. 24; no. 8; pp. 1113 - 1117
• Main Authors: Tian, Maoxin, Zhang, Qi, Zhao, Sai, Li, Quanzhong, Qin, Jiayin
• Format: Journal Article
• Language: English
• Published: IEEE 01.08.2017
• Subjects: Base stations; Downlink; MIMO; Multiple-input-multiple-output (MIMO); Mutual information; NOMA; nonorthogonal multiple access (NOMA); Optimization; secrecy sum rate; Silicon carbide
• ISSN: 1070-9908; 1558-2361
• DOI: 10.1109/LSP.2017.2711022

Nonorthogonal multiple access (NOMA) is expected to be a promising technique for future wireless networks. In this letter, we investigate the secrecy sum rate optimization problem for a downlink multiple-input-multiple-output NOMA system that consists of a base station, multiple legitimate users, and an eavesdropper. Our objective is to maximize achievable secrecy sum rate subject to successful successive interference cancellation constraints and transmit power constraint. The formulated optimization problem is nonconvex. Motivated by the relationship between mutual information rate and minimum mean square error, we propose to transform the secrecy sum rate optimization problem into a biconvex problem. The biconvex problem is solved by alternating optimization method where in each iteration, we solve a second-order cone programming. Simulation results demonstrate that our proposed NOMA scheme outperforms conventional orthogonal multiple access scheme.