A Stable Opportunistic Routing Scheme for Multi-hop Ad Hoc Networks

The main characteristic of the wireless medium is its broadcast nature, i.e., a unicast packet (destined for one specific node) is actually a one-hop broadcast packet to neighbors. However, the traditional routing transmit packets on the best path which is broken easily in practical dynamic environments and when the traffic rate is high. Thus, it leads to many retransmissions for route discovery and in turn gives a rise to heavy packet losses and long delays. In this paper, we propose a stable opportunistic routing mechanism of network layer for multi-hop ad hoc networks referred to as SOR which takes advantage of broadcast nature of wireless media. In SOR, two forward lists (FL) which contain the candidate forwarders are generated upon the route request and route reply messages to take advantage of path diversity, mitigate the redundant packets in the network and adapt to higher traffic rate. In order to reduce redundant packets in the network, we utilize the repeated packets forwarded by the candidate forwarders as confirmation. With simulations in NS-2 platform of several traffic rates and various channel state conditions, the superiority of SOR is verified over traditional routing protocol (AODV) and extremely opportunistic routing (ExOR) in throughput, end-to-end latency, packet delivery rate and adaption to dynamic radio environment.