On the Secrecy Design of STAR-RIS assisted Uplink NOMA Networks

TL;DR

This paper explores secure uplink NOMA communication aided by STAR-RIS, proposing algorithms for optimizing secrecy capacity and outage probability under different eavesdropper CSI scenarios, with simulation validation.

Contribution

It introduces joint beamforming algorithms for STAR-RIS assisted NOMA networks considering both full and statistical eavesdropper CSI, enhancing physical layer security.

Findings

Proposed AHB algorithm effectively maximizes secrecy capacity.

Derived exact SOP expression for constant-rate coding.

Simulation results confirm scheme effectiveness and provide deployment guidance.

Abstract

This paper investigates the secure transmission in a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted uplink non-orthogonal multiple access system, where the legitimate users send confidential signals to the base station by exploiting STAR-RIS to reconfigure the electromagnetic propagation environment proactively. Depending on the availability of the eavesdropping channel state information (CSI), both the full CSI and statistical CSI of the eavesdropper are considered. For the full eavesdropping CSI scenario, we adopt the adaptive-rate wiretap code scheme with the aim of maximizing minimum secrecy capacity subject to the successive interference cancellation decoding order constraints. To proceed, we propose an alternating hybrid beamforming (AHB) algorithm to jointly optimize the receive beamforming, transmit power, and reflection/transmission coefficients. While for the statistical eavesdropping CSI scenario, the constant-rate wiretap code scheme is employed to minimize the maximum secrecy outage probability (SOP) subject to the quality-of-service requirements of legitimate users. Then, we derive the exact SOP expression under the constant-rate coding strategy and develop an extended AHB algorithm for the joint secrecy beamforming design. Simulation results demonstrate the effectiveness of the proposed scheme. Moreover, some useful guidance about the quantification of phase shift/amplitude and the deployment of STAR-RIS is provided.