A reliable membership service for vehicular safety applications

Vehicular networks enable the development of driver assistance and automated driving applications that need to coordinate the behaviour of multiple vehicles. Safe coordination requires a level of communication reliability, determinism and timeliness that current systems do not offer. In particular, the challenge of reliably establishing membership in vehicular group communication systems has only partly been addressed. In this context, a group is often defined as the set of vehicles that are present in a given area. Existing membership protocols allow false negatives to occur - vehicles that are in the area may not be seen as members. Applications that use these protocols may critically be unaware of some nearby vehicles. We introduce a novel membership protocol that eliminates false negatives by integrating communication as a reliable means of detecting the physical presence of a vehicle, with (distance) sensing as a reliable means of detecting the absence of other vehicles. We compare an implementation of the membership protocol against a more traditional protocol in terms of error rate and overhead. We show our protocol delivers stronger guarantees with lower overhead, at the cost of requiring more sophisticated sensors.