Many applications in vehicular ad hoc networks (VANETs) need to have the knowledge of vehicles' location information, such as location-aware routing, vehicle management, and emergency notifications. Therefore, how to provide efficient location services has become an important issue in VANETs. Three mechanisms must be considered when designing a location service protocol: namely the delegation of location servers, the location update and query mechanisms. Existing location service protocols for VANETs may either incur high location update cost or cause long location query latency. To improve existing works, we propose a cost-based location service protocol for VANETs. A set of cost functions are defined to evaluate the performance of the location service protocol. According to the evaluation results of these cost functions, we can delegate proper number of location servers at proper locations so as to reduce the cost of location update and query. Simulation results justify the efficiency of the proposed protocol.
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