Research On The Multipath Routing Protocol For Mobile Ad Hoc Networks

Mobile Ad Hoc Network (Mobile Ad Hoc. a MANET) is a kind of self-organizing Network without a center, which consists of a group of Mobile terminal nodes with wireless communication transceivers. With multiple hops forwarding technology to quickly spread Network system, Network nodes can dynamically, optionally, frequently enter or leave the Network. As an important branch of wireless communication network, Mobile Ad Hoc network has following features:flexible agiligy, easy support and rapid mobility, overall system anti-damage ability, and low system cost. Because the mobile node computing power and storage capacity is low. and energy is limited. which has increased the difficulty of network integral design, network routing protocol research has especially become the current Ad hoc network research hotspot.This paper first introduces the mobile Ad Hoc network routing protocols. Routing protocols are classified, and the performances of different routing protocols are compared. Then some common single multipath routing protocols (DSR. DSDV. AODV. TORA) are emphatically analyzed. Single path routing protocol is very prone to local congestion, reduces the whole network throughput, increases end-to-end transport delay. In communication process.nodes'fast moving leads to links broken, therefore the rerouting is needed,which has a big impact on quality of service. This paper introduces multipath routing protocols and analyzes some typical multipath routing protocols (SMR. CHAMP. AODV-BR, AOMDV). Multipath routing establishes and maintains multiple paths. which have higher performance in routing delay, fault tolerance and reliability, etc. Multipath routing protocols in future mobile Ad Hoc network development will draw much attetion.This paper is based on the AOMDV multipath routing protocol research. We studied the routing table, RREQ and RREP packets, routing updating mechanism, routing maintenance and reliability in AOMDV protocol. In NS2 simulation experiments, by changing movement speed and pause time we analyze two protocols with respect to delivery rate, routing overhead and the end-to-end delay. Simulation results show that some shortcomings still exist in AOMDV. For example, during links'failure, the routing discovery process need be relaunched, which increases the average end-to-end delay. There is only one path for communication, the rest being in the standby mode. AOMDV does not make use of the multiple paths obtained within a routing process. Aiming at the shortcomings in AOMDV protocol, we proposed E_AOMDV protocol, by introducing early warning mechanism into AOMDV protocol to monitor the communication link. Once the links very prone to failure are found.they are replaced by backup links with higest priority. The communication continues. Simulation results indicate that E-AOMDV protocol has better performance.