Improving Fairness in Ad Hoc Networks Through Collision Rate Control

The 802.11 MAC protocol used in Mobile Ad Hoc Networks is designed to eliminate the hidden node problem through the use of the four way handshake RTS/CTS/DATA/ACK and to reduce packet drops due to collisions by listening to the channel before transmitting data. However, this protocol can lead to unfair channel utilisation among different flows, as some of the nodes may capture the channel for a long period and leave the rest to starve. This paper proposes a collision control algorithm aiming to improve fairness and channel utilisation in wireless networks. The algorithm monitors and polices the rate of MAC collisions among flows in order to distribute available resources across all participants. The evaluation results indicate that the proposed scheme achieve 99% fairness among the competing flows.