A station strategy to deter backoff attacks in IEEE 802.11 LANs

The IEEE 802.11 MAC protocol now prevailing in wireless LANs is vulnerable to selfish backoff attacks consisting in selection of short backoff times in the constituent CSMA/CA procedure. Administrative prevention of such attacks fails in ad hoc configurations, where stations' behavior cannot be mandated. In this paper we take an incentive-oriented game-theoretic approach whereby stations are allowed to maximize their payoffs (achieved success rates). Using a fairly accurate performance model we show that a noncooperative CSMA/CA game then arises with a payoff structure characteristic of a Prisoners' Dilemma. For a repeated CSMA/CA game, a novel SPELL strategy is proposed and shown to yield to simple algorithmic design. Assuming that the stations are rational players and wish to maximize a mean-value-type long-term utility, SPELL is further shown to deter a single attacker by providing a disincentive to deviate from SPELL.