A Packet Collision Avoidance Resource Selection Scheme for Reliable Intra-Platoon Message Delivery in a C-V2X Network

Reliable intra-platoon communication is critical for safety-related message delivery within a platoon of connected and automated vehicles. However, the intra-platoon communication is challenged by packet collisions due to hidden nodes and merging collisions due to vehicle mobility. To address these challenges, this paper proposes a packet collision avoidance resource selection (PCA-RS) scheme to enhance the standardized SPS scheme. The proposed PCA-RS scheme introduces three enhancement mechanisms, which aims to alleviate merging collisions and hidden-node collisions in intra-platoon message delivery. A resource partition mechanism is introduced to divide frequency-time resources in a selection window into two sets in order for vehicles (both platoon and non-platoon vehicles) moving in opposite directions to select different frequency-time resources and thus avoid potential merging collisions; an intra-platoon cooperative mechanism is introduced to enable the leader of a platoon to know the resource occupation status on the hidden nodes of the platoon according to the messages received from the last platoon member of the same platoon and thus avoid potential hidden-node collisions; and a merging collision detection mechanism is introduced to enable a non-platoon vehicle to detect the status of the frequency-time resources it currently occupies after the non-platoon vehicle changes a lane and thus avoids potential merging collisions among non-platoon vehicles due to lane-change maneuvers. Simulation results demonstrate that compared with the standardized SPS scheme, the proposed PCA-RS scheme can improve the reliability of intra-platoon message delivery in terms of the intra-platoon packet delivery ratio.