Distributed Fair Auto Rate Medium Access Control for IEEE 802.11 Based WLANs

Yanfeng ZHU  Zhisheng NIU  

Publication
IEICE TRANSACTIONS on Communications   Vol.E91-B   No.3   pp.854-861
Publication Date: 2008/03/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.3.854
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
Keyword: 
auto rate,  wireless LANs,  medium access control,  time-varying channel,  

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Summary: 
Much research has shown that a carefully designed auto rate medium access control can utilize the underlying physical multi-rate capability to exploit the time-variation of the channel. In this paper, we develop a simple analytical model to elucidate the rule that maximizes the throughput of RTS/CTS based multi-rate wireless local area networks. Based on the discovered rule, we propose two distributed fair auto rate medium access control schemes called FARM and FARM+ from the viewpoint of throughput fairness and time-share fairness, respectively. With the proposed schemes, after receiving a RTS frame, the receiver selectively returns the CTS frame to inform the transmitter the maximum feasible rate probed by the signal-to-noise ratio of the received RTS frame. The key feature of the proposed schemes is that they are capable of maintaining throughput/time-share fairness in asymmetric situation where the distribution of SNR varies with stations. Extensive simulation results show that the proposed schemes outperform the existing throughput/time-share fair auto rate schemes in time-varying channel conditions.