Secure robust relay beamforming: a convex conic approximation approach

In this study, the problem of secure robust relay beamforming for peer‐to‐peer networks in the presence of eavesdroppers has been optimised and relaxed by assuming the imperfect knowledge of eavesdroppers’ channel state information (CSI). Since the wiretap CSI is imperfect at its legitimate transmitter and receiver, it is a critical issue to make the optimisation problem robust against the channel uncertainty. The authors’ optimisation problem aims to maximise the probabilistic secrecy rate that is subject to keeping the probability of the transmission power of the relays below a specific threshold. The problem is shown to be non‐convex in its original form since the outage probability constraint does not admit a closed‐form expression and it is a non‐deterministic polynomial complete problem. They have presented three novel stochastic methods to handle the outage probability constraint. It has been shown that after some relaxation and randomisation, the problem can be represented as a convex optimisation problem which can be efficiently solved using interior point methods. Simulation results have been presented to verify the advantages of their methods.