Power efficient Opportunistic p-persistent CSMA for Wireless Networks

This paper proposes a power efficient p-persistent Carrier Sense Multiple Access (CSMA) employing multiuser diversity, called Opportunistic p-persistent CSMA (OpCSMA). At each idle time slot, an MT sends a packet if the corresponding channel gain is above the threshold which is determined such that the probability of accessing the medium is p for any idle slots. Also, the transmit power is controlled to maintain the constant signal-to-noise-ratio when the channel gain exceeds the cut-off fade depth. The analysis under the infinite user model shows that as traffic load grows, the transmit power consumption of the conventional p-persistent CSMA increases, whereas that of the OpCSMA decreases owing to multiuser diversity effect. Simulation results corroborate these findings in slow fading channels.