Research On Location Services For Geographic Routing In MANET

Mobile Ad Hoc network is a kind of networks, it does not need fixed infrastructure and can be constructed quickly and flexibly in the form of distributution and multi-hop. Routing protocols for mobile ad hoc networks have been the focus of research in recent decades. Owing to geographic information technology and the continuous development of terminal's capacity, location-based routing protocols become a new hotspot in recent years.Location service is the key issue in geographic routing protocols. We can obtain the latest accurate location information of the node by querying its location service. A good location service strategy should satisfy the following constraints: (1) Location service itself must be extensible. (2) The load should be balanced, and any node can not become a bottleneck. (3) The failure of any node should not affect the reachability of other nodes. (4) The query for the locations of near nodes should be able to be met with through local communication. (5) Costs should not only be as small as possible to query and update positions but cannot increase in proportion to the size of the nodes.The major research works in this paper include the following aspects.(1) Discusses the functions of location service and the factors affecting the performance of location services as well as the design methods. According to our proposed location service classification, typical location-based services for various types of geographic routing protocols are introduced, and their updating costs, requesting costs and the time complexity are analysed theoretically.(2) A set of evaluation criteria for node capability and grid region capability are presented. Based on these criteria, a weighted hash function for virtual hierachical location service (WVHLS) is designed to select nodes as location servers fairly with relatively higher probability to nodes of greater capability and less overhead of server's migration.(3) Finally, our improvements are evaluated using OPNET modeler. Experiment results show that, compared with VHLS, WVHLS can greatly reduce the possibility of location server migration and the cost of location updating, and is a more efficient location services.