Geometry-aware Probabilistic Communications for Urban Vehicular Ad Hoc Networks

Safety message exchange embodies a crucial proportion of inter-vehicle communications in Vehicular Ad Hoc Networks. In prior studies, direct single-hop broadcast seems a promising approach for simple transportation networks such as highways. In urban areas the geometry of roads and the placement of obstacles plays an important role in determining the efficient communication strategy. Here, due to the high penetration loss of the 5.9 GHz. wave passing through obstacles, single-hop communications between non-line-of-sight vehicles is not always the best choice. In this study we utilize geometric concepts to deploy appropriate power and hop control schemes for such environments. That is, based on the local geometry observed by the vehicle, it probabilistically decides on a single or multi-hop strategy upon each of its retransmission opportunities. As we shall see, the probabilistic decision on single or multi hop communications is proposed to allow for efficient delay- capacity tradeoffs in such environments.