Research On Routing Protocols For Wireless Mobile Ad Hoc Network And NS-2 Simulation

Ad hoc network is a dynamic multihop wireless network that is set up with multiple wireless devices without any infrastructure. With the flexibility, robustness and less investment, it has been widely used in military, emergency of natural disaster and mobile conference fields and etc..Routing is one of the key technologies in Ad hoc network, it is also the most important factor influencing the network performance.Much works on Ad hoc routing recently are aimed at finding a path connecting the source node and the destination node, they don't consider the transmission requirement of network traffic, once the data traffic exceed the maximum limit of network, the transmission quality of the data flow can't be guaranteed. With the appearance of the business required strict QoS (such as multimedia technology), it needs higher real-time performance when transmitting files. Thus providing QoS in Ad hoc networt is of great importance.The concept of Ad hoc network is introduced in this paper and the routing protocol of Ad hoc network is introduced in detail. An attempt has been made to compare the performance of four prominent routing protocols (AODV, DSR, DSDV and TORA) for mobile Ad hoc network. By comparing the packet delivery ratio, average end-to-end delay and normalized routing overhead with different node connections for these four routing protocols, the simulation method and results are presented, the dynamic effect can be seen by the"nam". According to the theoretical research and simulation results, we can find that AODV has better performance, it can support QoS and it can be extended easily. But it also has some flaws, such as poor QoS guarantee, long delay and high routing overhead. Therefore, an improved protocol (I-AODV) in mobile Ad hoc network is proposed and implemented in NS-2.The protocol is an expansion of AODV protocol. Taking bandwidth as the parameter for QoS, and decreasing the routing overhead by reducing the times of transmitting control packets, it provides better assurance for QoS in Ad hoc network. The simulation results show that it improves the real-time and normalized routing overhead performance of AODV.