MAC contention distributions for efficient geo-routing in vehicular networks

In this paper we evaluate a MAC-layer contention-based forwarding scheme for vehicular networks that prioritizes access according to node position. In particular, we consider two schemes that use a geometrically-increasing probability distribution for choosing the contention slots but, in the first case, the distribution is appropriately weighted, and in the second case, vehicles select the window size according to their position. We analytically evaluate the total and per-vehicle success probabilities and the average delay bounds. Our results show that a weighted geometric distribution effectively prioritizes the access based on position for a wide range of vehicle densities, while retaining the benefits of geometrical distributions with respect to success probabilities and delay bounds.