Analysis of Adaptive Control Scheme in IEEE 802.11 and IEEE 802.11e Wireless LANs

Bih-Hwang LEE  Hui-Cheng LAI  

IEICE TRANSACTIONS on Communications   Vol.E91-B   No.3   pp.862-870
Publication Date: 2008/03/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.3.862
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
IEEE 802.11e,  EDCAF,  HCF,  quality of service,  contention window,  

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In order to achieve the prioritized quality of service (QoS) guarantee, the IEEE 802.11e EDCAF (the enhanced distributed channel access function) provides the distinguished services by configuring the different QoS parameters to different access categories (ACs). An admission control scheme is needed to maximize the utilization of wireless channel. Most of papers study throughput improvement by solving the complicated multidimensional Markov-chain model. In this paper, we introduce a backoff model to study the transmission probability of the different arbitration interframe space number (AIFSN) and the minimum contention window size (CWmin). We propose an adaptive control scheme (ACS) to dynamically update AIFSN and CWmin based on the periodical monitoring of current channel status and QoS requirements to achieve the specific service differentiation at access points (AP). This paper provides an effective tuning mechanism for improving QoS in WLAN. Analytical and simulation results show that the proposed scheme outperforms the basic EDCAF in terms of throughput and service differentiation especially at high collision rate.