A Hierarchical Link Scheme in Multi-Hop VANETs with Delay Analysis for Congestion Scenario

摘要

Vehicular Ad-Hoc Networks (VANETs) as a part of intelligent transportation systems (ITS) are a new perspective to settle the traffic problem. Because of the high velocity, variational topology and such other characters, the link between VANETs and road side unit (RSU) is unstable. Besides, on account of the high cost of RSU, some places can’t be covered completely which make the Internet accessing difficult and accessing delay long. In this paper, we propose a hierarchical link scheme to help vehicles access the Internet based on delay analysis for congestion scenario. We select some moving accessing help points (AHPs) from vehicles in VANETs. Two different hierarchical schemes under the circumstances of whole road covered or not are proposed. When the RSUs are enough to cover the whole road fully, we propose the inward progressive hierarchical method. When the RSUs are not enough to cover the whole road, we propose the outward extend hierarchical method. According to the delay analysis, we can get the optimal hierarchy number. This hierarchical link scheme can decrease delay and make all vehicles access the Internet with delay guarantee. The simulation results indicate that our proposed hierarchical link scheme in VANETs can decrease the link delay effectively.