| Summary: | 碩士 === 國立清華大學 === 通訊工程研究所 === 90 === Routing protocols have been widely studied in Ad-hoc networks. However, most of the Ad-hoc network routing protocols are based on shortest path algorithms. In Ad-hoc networks, due to the mobility of the transmitters and/or the receivers, a receiver can easily move outside of the power range of its transmitter and this causes the wireless link between the two mobile nodes to fail. When link failure occurs during a communication session, it costs a lot to detect that the shortest routing path is no longer feasible and to retransmit the lost packets.In this paper, we propose a new routing algorithm called the Maximal Lifetime Routing algorithm (MLR). MLR is a hybrid type of Ad-hoc network routing algorithm. Every mobile node in the Ad-hoc network periodically exchanges position information collected using Global Positioning System (GPS) devices with other nodes.
With the GPS information, the mobile nodes can estimate the velocity and the moving direction of other mobile nodes. Hence, the mobile nodes can estimate the life time of the wireless links. When a new routing path is needed, the source node finds the path that has the longest life time. Furthermore, MLR can predict when the current routing path will fail due to the mobility of the mobile nodes along the path and find an alternative routing path before the path failure. Simulation result shows that MLR can effectively reduce average packet transmission delay and packet lost rate comparing to shortest path routing algorithm.
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