Robust beamforming and cooperative jamming for secure transmission in DF relay systems

Bin Li,Zesong Fei

doi:10.1186/s13638-016-0560-1

Abstract

In this paper, we study robust joint beamforming and cooperative jamming (CJ) in a secure decode-and-forward (DF) relay system in the presence of multiple eavesdroppers, in which a multi-antenna DF relay employs transmit beamforming to help the source deliver information to the destination and simultaneously generates Gaussian artificial noise to confuse these eavesdroppers. We assume that all the channel state information (CSI) is imperfectly known at the relay subject to norm-bounded CSI errors. Our objective is to maximize the achievable secrecy rate at the destination by jointly optimizing the transmit beamforming vector of information signals and the covariance matrix of jamming signals at the relay subject to its total transmit power constraint. Although this problem is non-convex and in general difficult to be solved, we obtain its optimal solution via the technique of semi-definite relaxation (SDR) together with a one-dimensional (1-D) search. Specifically, we prove that the SDR is tight for the problem of our interest. Finally, numerical results are provided to validate our proposed scheme.

Highlights

Secure wireless transmissions have drawn significant attention due to the broadcast nature of radio propagation and the inherent openness of the transmission medium
We focus on the robust joint beamforming and cooperative jamming (CJ) design for a DF-based relay system in the presence of multiple eavesdroppers, in which a single-antenna source sends confidential information to a single-antenna destination with the assistance of a multi-antenna relay, and a jamming signal is embedded in the transmitted signal of relay to improve secure communication
4 Numerical results we present simulation results to show the performance of the proposed robust joint beamforming and CJ design in DF relay system under channel uncertainty

Summary

Introduction

Secure wireless transmissions have drawn significant attention due to the broadcast nature of radio propagation and the inherent openness of the transmission medium. We focus on the robust joint beamforming and CJ design for a DF-based relay system in the presence of multiple eavesdroppers, in which a single-antenna source sends confidential information to a single-antenna destination with the assistance of a multi-antenna relay, and a jamming signal is embedded in the transmitted signal of relay to improve secure communication. 2) By jointly optimizing the transmit beamforming vector of information signals and the covariance matrix of jamming signals at the relay to maximize the achievable secrecy rate at the destination while guaranteeing the total transmit power constraint This problem is non-convex and in general difficult to be solved, we obtain its optimal solution via the techniques of semi-definite relaxation (SDR) together with a one-dimensional (1-D) search. The distribution of a circularly symmetric complex Gaussian (CSCG) random vector with mean vector x and covariance matrix is denoted by CN (x, ); and ∼ stands for “distributed as.”

System model and problem formulation

Problem formulation

Optimal solution

Conclusions