COFFEE: A Context-Free Protocol for Stimulating Data Forwarding in Wireless Ad Hoc Networks

Reputation based and credit-exchange based approaches have been studied extensively to enforce cooperation among non-cooperative nodes in wireless ad hoc networks. Most of the existing solutions are fundamentally context-based ones, which need to accurately identify selfish behaviors, securely maintain the context, and appropriately punish the selfish nodes. These requirements are extremely difficult to satisfy if not impossible. From a completely new angle, this paper proposes a context-free protocol, COFFEE, to enforce cooperation among selfish nodes, which has the ability to transmit a packet over the path successfully without the dependency on the information of other packets' transmission. Considering that every node in the network is rational, during the packet forwarding stage, if the intermediate nodes can not clearly tell whether the packet is destined to them or not, they can not simply drop the packet. Thus, in our proposed COFFEE protocol, through introducing several techniques, for any packet received by any node, the node thinks the packet could be destined to it and forwards the packet to find out the answer. Detailed analysis and performance evaluation have been conducted to demonstrate the effectiveness of the proposed protocol.