Research On Energy-efficient Geographic Routing Protocol In Ad Hoc Networks

Because of the advantage of no need of fixed infrastructure, which can rapidly provide temporary networking, Ad Hoc network meets the communication requirement on special occasions. It has been a research hotspot in network area. Ad Hoc network has many features such as highly dynamic topology, multi-hop transmission, unreliable wireless channel, limited energy, which lead to the result that the traditional routing protocols are not suitable for Ad Hoc networks. The design of the applicable routing protocol is a hot issue.For geographic routing protocols, the current node only needs to know its neighbor nodes' location instead of the whole network information. Geographic routing protocols have characteristics of no need to store routing table, avoidance of large-area flooding, small amounts of control overhead and excellent extensibility, which are particularly suitable for Ad Hoc networks. GPSR(Greedy Perimeter Stateless Routing) is a typical geographic routing protocol. In the greedy forwarding mode, the current node chooses the neighbor node nearest to the destination node as its next hop. When a node is in a routing void zone, it forwards packet on the edge of this void zone. Greedy forward is executed until a node closer to the destination node is found.According to the energy model of Ad Hoc network, there is a linear relationship between the energy consumption and the square or even higher power of transmission distance. Even if the transmission distance is not too long, the energy will still be consumed too much. In consideration of the limited energy, EGRP(Energy-efficient Geographic Routing Protocol) is proposed on the basis of GPSR in this thesis. Benefit function is defined taking distance and angle into account. And the neighbor node with biggest benefit function value is chosen as the secondary destination node. Then, an optimal-energy path to the secondary destination node is selected based on local information. The packet is transmitted to the secondary destination node hop by hop according to the selected path. The transmission is repeated as the above steps until the packet reaches its destination. The arrangement of intermediate node and selection of optimal-energy path can effectively reduce the energy consumption, and lower the death probability of nodes. In addition, it can prolong the survival time, and improve the overall performance of network.The simulation with the two protocols is done in NS 2. The network survival time, energy variance and packet delivery rate are compared. The result shows that the proposed EGRP is an efficient and feasible protocol for Ad Hoc networks.