Virtual Vertex Routing (VVR) for Course-Based Vehicular Ad Hoc Networks

In vehicular ad hoc networks (VANETs), geographic routing protocols appear to be a fascinating option since they have generally low delay and small routing overhead and GPS devices are becoming affordable. However, we reveal that geographic routing protocols suffer from routing holes when nodes are distributed only on lines such as cars on roads, trains on rails, and ships on courses. To tackle this problem, we propose a novel geographic routing protocol, virtual vertex routing (VVR), which uses the information of the lines. Using graph formulation, we introduce a new concept, the proximity of a vertex (or a virtual vertex). An intermediate node in this proximity performs routing toward the destination by Floyd algorithm. For routing holes, we propose two countermeasures: greedy routing (VVR-GR) and face routing (VVR-FR). The latter can guarantee the packet delivery. Extensive simulations are performed to show that VVR outperforms GPSR and AODV.