Contention resolution in wireless LANs using frequency-domain backoff

Recent advancements in PHY data rates of communication technologies require efficient MAC mechanisms. IEEE 802.11 MAC compels nodes to defer transmissions to avoid collisions and maintain random and fair channel access. Contention time degrades network performance in terms of bandwidth and delays; this problem exaggerates at higher data rates. In this paper, we propose a frequency-domain backoff scheme, where each OFDM data subcarrier is assigned an integer and then RTS is transmitted using a randomly chosen data subcarrier. In parallel using an additional listening antenna, each node listens on whole band for all active subcarriers. Node that transmits on smallest subcarrier wins channel access and is replied with CTS. Unlike IEEE 802.11 backoff, this handshaking frequency-domain backoff mechanism has lesser and fixed contention overhead. We also compute goodput efficiency of proposed mechanism using an analytical model. Our analysis suggests that proposed mechanism has higher efficiency gains in various network scenarios.