Geocast in vehicular environments: caching and transmission range control for improved efficiency

Geocast in vehicular ad hoc networks allows to realize applications like virtual warning signs for improved road safety, which address a geographical area rather than an individual vehicle. In this paper we propose to include caching in the geocast forwarding scheme and improved neighborhood selection to address in particular the high velocities of vehicles. High velocities of vehicular networks are a major difference to usual mobile ad hoc networks which assume only moderate node movement. We show that a cache for presently unforwardable messages caused by network partitioning or unfavorable neighbors can significantly improve the geocast delivery success ratio. The improved neighborhood selection taking frequent neighborhood changes into account significantly decreases network load and decreased end-to-end delivery delay.