A rate separation mechanism for performance improvements of multi-rate WLANs

Abstract

The fundamental access mode of the IEEE 802.11 MAC protocol is contention based. If the traffic load is heavy or the number of contending station is large, the number of collisions is increased and it leads to the performance degradation. In this paper, we propose a mechanism that tries to reduce the number of collisions by separating and grouping the contending stations and distributing those groups over time in multi-rate WLANs. For this, we issue the trade-off relationship between the throughput fairness and temporal fairness in multi-rate WLANs. Considering the trade-off relationship, we propose a Rate Separation (RS) mechanism in which the grouping is done based on the current transmission rates of contending stations. From our simulation study, we show that the proposed mechanism reduces the number of collisions and achieves improved performance over the IEEE 802.11b WLANs.