Multi-hop Connected Probability In VANETs

ABSTRACT:Vehicular Ad hoc NETworks (VANETs) distinguish from traditional Mobile Ad hoc NETworks (MANETs), because VANETs are aimed at constructing wireless connection among highly dynamic vehicles. Vehicles are travelling along with the road and have little freedom to move randomly to all direction. These features makes the study of VANETs distinct from other research. Due to the high mobility and dynamic topology, the direct communication range is limited. Therefore, the multi-hop mode is needed.This article focuses on the multi-hop connectivity issue in VANETs. Most of previous related researches were depended on two premises. One was that the consecutive links were independent and identical distributed. The other one was the connectivity analysis was based on the pure geometrical model, i.e. two nodes had a link if their Euclidean distance is less or equal to the transmission radius. These two assumptions are a little bit too simple and ideal to model the realistic scenario.First, we start to work on the mobility model in VANETs and survey on the existed research works thoroughly. Second, because the simplistic assumption of independent and identical distribution between links in multi-hop networks, we derive the two-hop connected probability with the consideration of correlation between links. Third, improved on pure geometrical model, we use log-normal shadow fading model to incorporate the randomness into the analysis. Last, we conclude the entire article.Combining the theoretical analysis with the simulating validation, we calculate the appearing probability that at least one vehicle shows up in the intermediate area, and then we obtain the two-hop connected probability distribution. Under the condition of varying arrival rate and moving speed, we analyze the impact of these two parameters on the connected probability. Compared the pure geometrical model to the shadow fading model, two-hop connected probability has different expressions in two models. We also discuss the switching point of one-hop and two-hop connected probability in shadow fading model.The major contribution of this work is as follow:1) Replace the link independent assumption with link correlation in multi-hop networks.2) Make use of log-normal shadow fading model instead of pure geometrical model to derive the connected probability.