Based On The Backup Paths To Improve AODV Routing Protocol

Ad hoc on demand distance vector routing protocol AODV is a classic on-demand routing protocol, and it has been widely used. In the implementation of AODV, the network nodes establish the reverse route and forward route according to the first received RREQ messages, and directly discard the duplicate RREQ messages. Obviously, this method can not ensure excellent performence. When interruption happens, the AODV needs the upstream node or source node to find a new route to the destination node, which will result in large delay.This thesis describes the whole process of AODV routing protocol in detail. For the defects of AODV like imbalance of overhead and slow velocity of link-fix, we propose a modified routing protocol named BCOAODV to improve the AODV routing protocol. This protocol considers the value of backup paths and the value of routing overhead as important performance index, it can effectively balance the network overhead and fix the link by backup paths when interruption happens.In order to achieve quick link-fix and optimize the repair strategy of AODV, the format of RREQ, RREP messages and routing table have been modified on BCOAODV routing protocol. Then this thesis makes a detailed analysis and designs on BCOAODV s whole working process in route discovery and route maintenance. We implement BCOAODV routing protocol algorithm in NS2 simulation platform, and then compare the traditional AODV routing protocol and AODV-BR routing protocol with BCOAODV routing protocol in data distribution rate, average delay and control overhead. Simulation results show that BCOAODV is higher than the AODV and AODV-BR in packet delivery fraction, less than in control overhead. When the nodes move fast, BCOAODV gets lower average delay than ADOV and AODV-BR.