V2X Communications for Maneuver Coordination in Connected Automated Driving: Message Generation Rules

Connected automated vehicles (CAVs) can use vehicle-to-everything (V2X) communications to exchange their driving intentions and coordinate their maneuvers. Message generation rules are necessary to decide when and how maneuver coordination messages (MCMs) should be generated. The design of these generation rules must consider the critical nature of maneuver coordination and the limited bandwidth available for V2X communications. This study proposes the first two sets of V2X message generation rules for maneuver coordination between CAVs. The Risk proposal increases the rate at which vehicles generate MCMs when vehicles detect a potential safety risk. With the Tracking Trajectories proposal, vehicles generate a new maneuver coordination message when they significantly modify their planned trajectory. For both proposals, the messages include the planned and possible desired trajectories of the ego vehicle. The evaluation shows that the proposed generation rules efficiently support maneuver coordination and offer a balance between more frequent updates of the driving intentions of CAVs and lower coordination time and better control of the V2X communications channel load. This study also reveals that congestion control protocols can significantly impact maneuver coordination.