Research & improvement of AODV supporting networks with unidirectional links

It is only simply assumed that network links are bidirectional in most routing protocols. However unidirectional links may exist in a real network due to the variation of transmission power in different nodes, the affection of noise and other signal propagation. We find that the AODV protocol can not support unidirectional links and the Hello mechanism increases overmuch overhead on traffic. In this paper, we introduce an improved Hello mechanism named Hello2 mechanism which can reduce overhead and overcome the phenomenon of unidirectional links. We present a scalable and efficient way to provide this abstraction by finding and maintaining multi-hop reverse routes to each unidirectional link. We simulate the mechanism based on the modified AODV version that uses Hello2 to route packets in networks with unidirectional links. The simulation results show that the packet delivery is substantially increased and the overhead is distinctly reduced in unidirectional networks.