A Region-Based Hierarchical Location Service with Road-Adapted Grids for Vehicular Networks

In VANETs, it is very important to communicate between two vehicles, but how to get the correct position of a vehicle is not easy. Due to vehicles are moving fast, topology in VANETs changes rapidly. As a result, location services processed in VANETs are more difficult than in MANETs. In our thesis, we propose a hierarchical location service system, it provides a low cost and rapid service. First, we select the main arteries to divide network into grids because of there are more vehicles than in normal roads, and then design a mechanism that when vehicles need to send update packets. This mechanism can decrease the number of update packets and still gain correct vehicles´ location. Second, we design grids with three levels, the higher the level, the larger the area. Each level stores update packets sent within its area. Vehicles using our system can find the destination vehicle distributedly within a small area; if the target is not within this area, then find within a larger area. Besides, we propose a packets collection method, it can be adjusted with different size of collection area. The simulation results show that our scheme could decrease the number of location update packets effectively, and keep high success rate of location service.