Weighted Sum-Rate Maximization for Rate-Splitting Multiple Access Based Secure Communication

TL;DR

This paper introduces a novel secure beamforming scheme based on rate-splitting multiple access (RSMA) that enhances weighted sum-rate performance in multi-user secure communications by effectively managing interference and ensuring secrecy.

Contribution

It proposes a new RSMA-based secure beamforming design with a successive convex approximation approach, improving upon traditional multi-user linear precoding methods.

Findings

Outperforms conventional MULP in weighted sum-rate.

Ensures user secrecy rate requirements.

Uses a low-complexity iterative algorithm.

Abstract

As investigations on physical layer security evolve from point-to-point systems to multi-user scenarios, multi-user interference (MUI) is introduced and becomes an unavoidable issue. Different from treating MUI totally as noise in conventional secure communications, in this paper, we propose a rate-splitting multiple access (RSMA)-based secure beamforming design, where user messages are split and encoded into common and private streams. Each user not only decodes the common stream and the intended private stream, but also tries to eavesdrop the private streams of other users. We formulate a weighted sum-rate (WSR) maximization problem subject to the secrecy rate requirements of all users. To tackle the non-convexity of the formulated problem, a successive convex approximation (SCA)-based approach is adopted to convert the original non-convex and intractable problem into a low-complexity suboptimal iterative algorithm. Numerical results demonstrate that the proposed secure beamforming scheme outperforms the conventional multi-user linear precoding (MULP) technique in terms of the WSR performance while ensuring user secrecy rate requirements.