Mitigating starvation in wireless ad hoc networks: multi-channel MAC and power control

The IEEE 802.11 DCF (Distributed Coordination Function) is based on CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance). However, the CSMA-based random access protocol can cause serious unfairness or flow starvation. In this paper, we propose a multi-channel MAC with the power control (STPC-MMAC) to mitigate the starvation by exploiting the multiple channels and improving the spatial reuse of wireless channel. The main idea of our proposal is to use the IEEE 802.11 Power Saving Mechanism (PSM) with different transmission power levels used in the Announcement Traffic Indication Message (ATIM) window and the data window. All nodes transmit the ATIM messages with the maximum power while negotiating for the data channel in the ATIM window, and use the minimum required transmission power for their data transmissions in the data window on the negotiated channels. The simulation results show that the proposed STPC-MMAC can improve the network performance: aggregate throughput, average delay, energy efficiency and especially fairness index.