QoS Aware Transmit Beamforming for Secure Backscattering in Symbiotic Radio Systems

TL;DR

This paper proposes a QoS-aware transmit beamforming method to enhance secure backscatter communication in symbiotic radio systems, optimizing secrecy rate while maintaining primary system QoS.

Contribution

It introduces an alternating optimisation algorithm for joint beamforming and power sharing, improving secrecy rate in secure backscatter symbiotic radio networks.

Findings

The proposed algorithm maximizes secrecy rate effectively.

Numerical results confirm the optimality and low complexity of the solution.

Design insights and performance gains over benchmarks are demonstrated.

Abstract

This paper focuses on secure backscatter transmission in the presence of a passive multi-antenna eavesdropper through a symbiotic radio (SR) network. Specifically, a single-antenna backscatter device (BD) aims to transmit confidential information to a primary receiver (PR) by using a multi-antenna primary transmitter's (PT) signal, where the received symbols are jointly decoded at the PR. Our objective is to achieve confidential communications for BD while ensuring that the primary system's quality of service (QoS) requirements are met. We propose an alternating optimisation algorithm that maximises the achievable secrecy rate of BD by jointly optimising primary transmit beamforming and power sharing between information and artificial noise (AN) signals. Numerical results verify our analytical claims on the optimality of the proposed solution and the proposed methodology's underlying low complexity. Additionally, our simulations provide nontrivial design insights into the critical system parameters and quantify the achievable gains over the relevant benchmark schemes.