Adaptive RTS/CTS-Exchange and Rate Prediction in IEEE 802.11 WLANs

Wonbae PARK  Taejoon KIM  

Publication
IEICE TRANSACTIONS on Communications   Vol.E101-B   No.6   pp.1485-1493
Publication Date: 2018/06/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2017EBP3269
Type of Manuscript: PAPER
Category: Terrestrial Wireless Communication/Broadcasting Technologies
Keyword: 
rate adaptation,  coherence time,  RTS/CTS frame,  IEEE 802.11 WLANs,  

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Summary: 
Regarding IEEE 802.11 wireless local area networks (WLANs), many researchers are focusing on signal-to-noise ratio (SNR)-based rate adaptation schemes, because these schemes have the advantage of accurately selecting transmission rates that suit the channel. However, even SNR-based rate adaptation schemes work poorly in a rapidly varying channel environment. If a transmitter cannot receive accurate rate information due to fast channel fading, it encounters continuous channel errors, because the cycle of rate adaptation and rate information feedback breaks. A well-designed request-to-send/clear-to-send (RTS/CTS) frame exchange policy that accurately reflects the network situation is an indispensable element for enhancing the performance of SNR-based rate adaptation schemes. In this paper, a novel rate adaptation scheme called adaptive RTS/CTS-exchange and rate prediction (ARRP) is proposed, which adapts the transmission rate efficiently for variable network situations, including rapidly varying channels. ARRP selects a transmission rate by predicting the SNR of the data frame to transmit when the channel condition becomes worse. Accordingly, ARRP prevents continuous channel errors through a pre-emptive transmission rate adjustment. Moreover, ARRP utilizes an efficient RTS/CTS frame exchange algorithm that considers the number of contending stations and the current transmission rate of data frames, which drastically reduces both frame collisions and RTS/CTS-exchange overhead simultaneously. Simulation results show that ARRP achieves better performance than other rate adaptation schemes.