Security-Reliability Tradeoff for Hybrid Automatic Repeat Request-Assisted NR V2X Communication

Hybrid Automatic Repeat reQuest (HARQ) feedback is one of the key technologies for enhancing the performance of New Radio (NR) Vehicle-to-Everything (V2X) communication. However, for NR V2X messages, HARQ-based retransmission not only improves its delivery performance, but also poses a significant threat to its confidentiality. This paper investigates the Security-Reliability Tradeoff (SRT) of HARQ-assisted NR V2X. To accurately describe the SRT behavior in the V2X scenario, a theoretical framework based on stochastic geometry is developed, carefully considering the random device distributions and physical layer settings of NR V2X. Numerical results prove that this theoretical framework can effectively capture the success probability and secrecy probability of V2X communications under different configurations, including transmission rounds, resource selection, and power control. Furthermore, our analysis shows that the SRT of HARQ-assisted NR V2X can be adjusted by finely tuning the considered configurations.