Opportunistic Routing in Presence of Selfish Nodes for MANET

Opportunistic Routing protocols use broadcast nature of wireless communication to improve packet delivery from source to destination in mobile ad hoc network (MANET). In traditional routing protocols for MANET, each node uses the best neighbor for forwarding packet to destination. In opportunistic routing, a node selects and prioritizes multiple nodes which can act as potential packet forwarders. Similar to traditional routing protocols, opportunistic routing assumes that all nodes participating in the network are honest and cooperative. However, this is practically difficult in an open MANET. Few nodes participating in the network may behave selfishly; these nodes drop packets and do not offer service to other nodes. Such behavior exhibited by the nodes may cause a collapse of MANET communication. The selfish behavior attack is addressed by researchers for many existing MANET routing protocols. There are just a few works, which address selfish nodes attack for opportunistic routing protocols. The paper proposes an opportunistic routing protocol which can overcome the presence of selfish nodes. The proposed protocol discovers reliable candidate nodes for packet forwarding using a new metric called ‘path goodness’. The path goodness metric takes into account trustworthiness of the nodes on a path to the destination. The protocol decides trustworthiness of the nodes using packet forwarding behavior of the nodes. The work is a trust based extension of CORMAN opportunistic routing protocol. Simulation results show that, the proposed opportunistic routing protocol improves the packet delivery ratio by approximately 10 % in the presence of selfish nodes.