Towards efficient opportunistic communications: A hybrid approach

Wireless mesh networks are well-recognised by their self-organising properties. End-to-end routing protocols are primarily responsible for achieving these advanced features. However, wireless link failures can cause a route to be invalidated and subsequently removed from the routing table in nodes along the path to destination. Once the route is not available, packets addressed for that destination will be dropped. To improve the packet delivery ratio of those end-to-end protocols, we propose a hybrid approach that integrates features of opportunistic protocols into traditional end-to-end routing protocols in mesh networks. The idea is to buffer packets for which there is no path to the destination and attempt to deliver these buffered packets when an alternative route is found or to pass them to neighbours who might eventually be able to establish a route to the destination. To demonstrate the concept, we present the AODV-OPP - an extension of the AODV protocol that uses opportunistic communication. AODVOPP always prefers end-to-end route before attempting to send opportunistically to neighbours. Based on a number of systematic simulation scenarios, we observe that AODV-OPP consistently outperforms the original AODV, with a PDR gain greater than 8% most times and up to 45%.