Abstract
IEEE 802.11 standard backoff mechanism is vulnerable to selfish MAC layer misbehavior. A greedy node cheating on backoff rules can attain higher bandwidth and cause unfairness among nodes. In addition, selfish behavior is severe when honest nodes use longer contention window size. Contention overhead and unshared backoff value makes backoff mechanism vulnerable. Various studies have addressed misbehavior and overhead problems separately. In this paper, we address both of these problems by proposing a frequency-domain backoff mechanism to mitigate both backoff misbehavior and contention overhead. In this mechanism, the non-interfering capability of OFDM based PHY data-subcarriers is exploited and RTS packets are transmitted using single randomly chosen data-subcarrier. Using RTS, transmitters advertise their backoff value which in-turn is used to monitor selfish behavior at the receiver. Performance analysis suggest that the proposed mechanism promises lower overhead and higher efficiency gains over standard protocol in various network scenarios.