Mobile group based location service management for vehicular ad-hoc networks

Location service can be used to provide location information of vehicles for various applications including the position-based routing protocols in vehicular ad-hoc networks (VANET). The performance and the overhead of location service in VANET largely depends on the mechanisms to assign the vehicles to the location servers. Utilizing hash functions to determine the location server of a vehicle allows the mapping between the server and the vehicle to last long, and also enables even distribution of vehicles to the available servers. However, the geographical proximity of the vehicles and the servers is hard to be taken into account. On the other hand, the region based approaches divide the geographical area into subdivisions and assign local servers to the vehicles. Due to the high mobility of vehicles, though, the mapping between the servers and the vehicles changes frequently. We propose a dynamic mobile group based location service management (MG-LSM) mechanism, which dynamically groups the vehicles running nearby according to their moving direction with one of the vehicles in the group taking the role of location server. Since the location server is moving together with the vehicles receiving the service, geographical proximity between the location server and the vehicles can be maintained while the mapping between the location servers and the vehicles lasts long due to the characteristics of VANET mobility, i.e., majority of the vehicles running on the same road segment move with a similar velocity maintaining the proximity for a while. Through a simulation, the performance of the MG-LSM is compared with an existing approach. The simulation results show that the MG-LSM provides more accurate location discovery service with lower overhead.