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

Abstract

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.

Location-based forwarding in vehicular networks

“…The work presented in Chapters 4 and 5 was published, in increasing levels of maturity, at the ERCIM Workshop on eMobility (ERCIM) 2010 [4], the IEEE Vehicular Networking Conference (VNC) 2010 [5], ERCIM 2011 [6], and the International Conference on ITS Telecommunications (ITST) 2011 [7]. The work in [8] served as a basis for all of the modelling work presented in Part III of the thesis and has been published in the proceedings of VNC 2011.…”

“…This comes at the cost of an increased forwarding delay, since nodes have to wait for the next scheduled beacon before being able to forward a message. Piggybacking is therefore mainly used to flood delay-insensitive information [7] [50].…”

“…The RSU generates separate event messages for each approaching merging vehicle and each event message is routed separately. In [7] messages were routed using the simple geocast protocol as a single, aggregated event message, but it was shown that separate routing of event messages is more efficient because in this way event messages only reach those parts of the network where they are needed.…”

“…In [7] messages were routed using the restricted geocast protocol, both separately and aggregated. It was shown that separate routing of event messages gives a higher reliability.…”

“…Using Eq. (5.1) the size of the required merging gap (and thus of the event area), for the parameters chosen here, is always 45 m. The RSU generates and forwards new event messages every 6 seconds; accordingly t lif etime is also set to 6 s. We use this relatively high value for t lif etime to allow upstream travelling nodes to carry the information upstream, based on [7]. All nodes, including the RSU, beacon with a frequency of 1 Hz.…”