User-Oriented QoS Control Method Based on CSMA/CA for IEEE802.11 Wireless LAN System

Akira KISHIDA  Masashi IWABUCHI  Toshiyuki SHINTAKU  Tetsu SAKATA  Takefumi HIRAGURI  Kentaro NISHIMORI  

IEICE TRANSACTIONS on Communications   Vol.E96-B   No.2   pp.419-429
Publication Date: 2013/02/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.419
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Quality of Communication Services Improving Quality of Life)
user-oriented,  QoS,  fixed backoff,  CSMA/CA,  IEEE802.11,  

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The IEEE 802.11 distributed coordinated function (DCF) adopts carrier sense multiple access with collision avoidance (CSMA/CA) as its medium access control (MAC) protocol. CSMA/CA is designed such that the transmission from any one station does not have priority over any other. In a congested environment with many DCF stations, this design makes it difficult to protect channel resources for certain stations such as when products are used for presentation at exhibitions, which should be protected based on priority. On the other hand, The IEEE 802.11 enhanced distributed channel access (EDCA) provides a quality-of-service (QoS) mechanism for DCF. However in EDCA, transmission opportunities are allocated based on not individual stations but on the defined traffic type of applications. This paper proposes a distributed dynamic resource allocation method that enables control of flexible bandwidth allocation to each specific station. The proposed method controls the priority level and can coexist with conventional CSMA/CA. Moreover, the proposed method improves the system throughput. Specifically, under the coexistence environment with DCF stations, the proposed method is able to obtain up to over 300% higher user throughput characteristic compared to the case in which the proposed method is not introduced. In addition, under non-coexistence environment, all the proposed stations achieve 70% higher throughput than DCF stations when the number of stations in a network is 50.