Secure Beamforming for MIMO Two-Way Communications With an Untrusted Relay

Abstract

This paper studies the secure beamforming design in a multiple-antenna three-node system where two source nodes exchange messages with the help of an untrusted relay node. The relay acts as both an essential signal forwarder and a potential eavesdropper. Both two-phase and three-phase two-way relay strategies are considered. Our goal is to jointly optimize the source and relay beamformers for maximizing the secrecy sum rate of the two-way communications. We first derive the optimal relay beamformer structures. Then, iterative algorithms are proposed to find source and relay beamformers jointly based on alternating optimization. Furthermore, we conduct asymptotic analysis on the maximum secrecy sum-rate. Our analysis shows that when all transmit powers approach infinity, the two-phase two-way relay scheme achieves the maximum secrecy sum rate if the source beamformers are designed such that the received signals at the relay align in the same direction. This reveals an important advantage of signal alignment technique in against eavesdropping. It is also shown that if the source powers approach zero, the three-phase scheme performs the best while the two-phase scheme is even worse than direct transmission. Simulation results have verified the efficiency of the proposed secure beamforming algorithms as well as the analytical findings.

Erasure channel modelling–based secure bit allocation schemes for multipath routing in wireless sensor networks

“…If some sensor nodes are captured by eavesdroppers, they are thought to be untrusted. The beamforming technique for physical layer security and its performance is discussed with untrusted relays in Mo et al, 13 Wang et al, 14 and Aggarwal and Trivedi, 15 where the relays played as both helpers and potential eavesdroppers. Choi 11 proposed a novel scene of eavesdroppers wiretapping the WSN in which there are four types of nodes: a source node (SN) transmits packets to a destination node (DN) through relay nodes (RNs).…”

Security–reliability tradeoff analysis of untrusted energy harvesting relay networks

“…In addition, cooperative jamming approach was coined to improve the security of cooperative transmission with untrusted relay by degrading the channel conditions of eavesdroppers. 12 In Mo et al, 13 jointly optimal the source and relay beamformers to maximize the secrecy rate was designed for a multiple-input multiple-output (MIMO) two-way untrusted AF relay network 14 demonstrated that the achievable ergodic secrecy rate (ESR) decreases as the number of untrusted relays increases. A constellation-rotation aided scheme was proposed to avoid information leakage to the untrusted relay and enhance the transmission reliability in Xu et al 15 Recently, some works about untrusted energy harvesting relay networks have been considered in the context of physical layer security.…”

Secrecy in Wireless Information and Power Transfer for One-Way and Two-Way Untrusted Relaying with Friendly Jamming

“…In [6], a successive relaying scheme was proposed to secure the AF relaying network with multiple untrusted nodes and it was shown that the scheme could improve the security performance. In addition, secure beamforming with untrusted relay was considered in [7,8].…”