Secure V2V Communications via Relays: Resource Allocation and Performance Analysis

In this letter, we will investigate the joint relay selection and subcarrier allocation problem for decode-and-forward relay assisted secure vehicle-to-vehicle (V2V) communications, where the eavesdroppers could be any illegal receivers or non-intending information destinations. The joint relay selection and subcarrier allocation scheme will be proposed to minimize the secure outage probability of each <inline-formula> <tex-math notation="LaTeX">${V_{\text {Tx}}}$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">${V_{\text {Rx}}}$ </tex-math></inline-formula> pair while guaranteeing fairness. Specifically, the joint relay selection and subcarrier allocation problem in secure V2V communications is formulated into a random bipartite graph (RBG) model. The considered problem is then equivalent to generate the maximum matching on every sample of the RBG, thus it can be solved by R²HK algorithm with low complexity. By analyzing the properties of the RBG model-based maximum matching, the closed-form approximation formula of the secure outage probability is then obtained. Simulation results will not only verify the accuracy of theoretical derivations, but also show the performance improvement of the proposed approach.