Dissemination protocols to support cooperative adaptive cruise control (CACC) merging

Cooperative adaptive cruise control (CACC) is a form of cruise control in which vehicles cooperatively control their speed using wireless communication. Previously we have implemented CACC using beaconing: the regular broadcasting of status information using 802.11p. Currently we are concerned with extending both our beaconing mechanism and our CACC system to support automatic CACC merging. In this paper we focus on extending the beaconing mechanism to disseminate the required merging. We propose three beacon-based dissemination protocols and evaluate how well they are able to support automatic CACC merging. All protocols piggyback merging information on the CACC beacons, without changing the timing of the beacons. Our main goal is to identify which protocol can disseminate merging information during a CACC merging manoeuvre most efficiently. We show that all three protocols have low loss rates but that the impact on the network load differs per protocol.