One/Zero Fairness Problem of MAC Protocols in Multi-Hop Ad Hoc Networks and Its Solution

Abstract

In this paper, we investigate the fairness problem of MAC protocols in practical multi-hop ad hoc networks where carrier sensing (CS) range and interference range are much larger than communication range. By using IEEE 802.11 as a study case, we identify that contention based asynchronous MAC protocols can suffer from, a fundamental fairness problem, i.e., some flows seize the whole channel capacity while others virtually get nothing. This problem is known as one/zero fairness problem. To address the problem, we propose a hybrid MAC protocol that operates in a single channel and employs sender-initiated (SI) and receiver-initiated (RI) schemes as well as a power control mechanism. Simulation results show that the hybrid protocol relieves the one/zero fairness problem to a large extent without impairing aggregate throughput significantly, and in some scenarios, it even improves aggregate throughput dramatically.