Distributed Channel Access for QoS Control in Link Adaptive Wireless LANs

Ryoichi SHINKUMA  Junpei MAEDA  Tatsuro TAKAHASHI  

IEICE TRANSACTIONS on Communications   Vol.E89-B   No.6   pp.1846-1855
Publication Date: 2006/06/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.6.1846
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
wireless LAN,  IEEE802.11e,  QoS control,  distributed channel access,  link adaptation,  fairness,  

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In wireless local area networks (WLANs), the necessity of quality-of-service (QoS) control for uplink flows is increasing because interactive applications are becoming more popular. Fairness between flows transmitted by stations with different physical transmission rates must be ensured in QoS control for link-adaptive WLANs, which are widely used nowadays. We propose a novel distributed access scheme called QC-DCA to satisfy these requirements. QC-DCA adaptively controls the parameters of carrier sense multiple access with collision avoidance (CSMA/CA). QC-DCA has two QoS control functions: guarantee and classification. QC-DCA guarantees target throughputs and packet delays by quickly adjusting CSMA/CA parameters. In QoS classification, the difference of throughputs and packet delays between different QoS classes is maintained. These two functions allow QC-DCA to suppress the unfairness caused by differences of transmission rates in the physical layer. We evaluated the throughput and delay performances of our scheme using computer simulations. The results show the viability of our scheme.