Fair Packet Forwarding in MANETs with Anonymous Stations: A Game-Theoretic Approach

A station of a mobile ad-hoc network (MANET) may selfishly refuse to forward transit packets as it shortens the battery life and takes up a portion of the bandwidth that could be used for source packets. Due to a high degree of station anonymity, selfishness meets with little punishment. The well-known watchdog mechanism can be used to check if an adjacent station forwards packets. We point out that a watchdog may be unable to tell source from transit packets, which enables undetectable manipulation of local congestion controls in selfish stations. We allow each station to set its source packet admission threshold so as to maximise a throughputand reputation-related payoff. The nature of possible Nash equilibria of the resulting noncooperative game are examined for a generic model of packet forwarding and symmetric traffic flows. A novel packet forwarding protocol called FT is proposed and the payoffs it yields are approximately analysed.