Adaptive DENM Retransmission for Enhancing Reliability of Mixed V2X Traffic

Decentralized Environmental Notification Message (DENM) retransmission schemes have been suggested to increase the Packet Delivery Ratio (PDR) for DENMs, they compromise communication performance due to resource collisions with Cooperative Awareness Messages (CAM) in mixed-traffic environments. To address this issue, this letter proposes the Adaptive DENM Retransmission (ADR) scheme, which adaptively adjusts DENM retransmission resources based on the Channel Busy Ratio (CBR) estimated by the transmitting user equipment. Simulation results show that the ADR scheme improves PDR for both CAMs and DENMs, with greater improvements in congested wireless channels.