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Overhead And Load Balance Of Routing Protocols In Mobile Ad Hoc Network

Posted on:2010-09-29Degree:MasterType:Thesis
Country:ChinaCandidate:F F ZouFull Text:PDF
GTID:2178360302959860Subject:Computer applications
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In MANET (Mobile Ad hoc Network), mobile nodes operate using batteries and can move freely. Each mobile node is equipped with wireless antennas and communicates with each other over wireless links. Due to the transmission limit of radio, data packets are forwarded by intermediate nodes from source node to corresponding destination node. Compared with conventional wired network, the mobile nodes'capacities are relatively small and the network topology of MANET has high dynamic nature, and thus it is a critical challenge for the development of routing protocols. First, the control overhead, which includes route discovery procedure overhead, route maintenance procedure overhead etc., to maintain route information is a great burden for MANET. Second, the problem of load balance is more important in MANET, because some nodes may die of exhausting energy and the contention and collision between wireless channels will be very serious if there is hot-spot problem. So it is very necessary to decrease the control overhead of routing protocols and balance the load of nodes.The main contributions of this dissertation are given as following.Firstly, that original DSR (Dynamic Source Routing) uses flooding route request blindly for route discovery procedure will cause significant routing overhead and result in serious contention and collision between wireless channels which are known as broadcast storm. And thus, this dissertation proposes a localization routing discovery mechanism. By combining the route cache mechanism and TTL mechanism of route request in DSR, it uses the obsolete route in route cache to predict the location of destination node and then modifies the TTL value to limit the route request into a smaller area effectively based on the prediction.Secondly, this dissertation proposes a route stability algorithm based on the lifetime prediction of routes. It evaluates the node stability and link stability utilizing the dynamic nature, such as energy drain rate and relative mobility estimation rate of nodes. Integrating these two metrics by using a route lifetime prediction algorithm, it selects the least dynamic route with the longest lifetime for persistent data forwarding and reduces the times of route discovery procedure significantly.Thirdly, that DSR select the route with the least hops ignoring the state of node such as load, mobility etc may result in two tendencies. First, the traffic follow may be centralized into nodes located in central area. Second, some unstable nodes may be selected for data forwarding. This dissertation proposes a load balance routing protocol based on node capacity. It uses the MAC information of node in cross-layer manner and defines the node capacity as the transmitting success rate in MAC level,then it selects a relative stable route for data forwarding and balances the load of node in MANET based on the node capacity metric.
Keywords/Search Tags:mobile ad hoc network, routing protocol, routing overhead, load balance, localization routing discovery, routing stability, cross-layer design
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