Coding opportunity is critical to the performance of intra-session network coding in ad hoc networks.However

coding opportunity can not be discovered effectively with most distance-vector routing protocols including AODV which only knows one-hop neighbor node information.From the aspect of how much network topology information needs to be known

the condition under which the coding opportunity can be discovered effectively was proposed and the sufficiency and necessity of the condition was analyzed.Also the condition was implemented based on AODV routing protocol and validated with the help of real experiment and simulation.The results show that the proposed condition is correct and can improve the performance of wireless ad hoc networks effectively.