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An Adaptive Contention Windows Adjustment Scheme Based on the Access Category for OnBord-Unit in IEEE 802.11p  

Park, Hyun-Moon (Hybrid Signal Processing Research Center of KETI)
Park, Soo-Hyun (School of Business Kookmin University)
Lee, Seung-Joo (Department of Information and Communication Engineering of Seoil University)
Publication Information
Journal of the Institute of Electronics Engineers of Korea CI / v.47, no.6, 2010 , pp. 28-39 More about this Journal
Abstract
The study aims at offering a solution to the problems of transmission delay and data throughput decrease as the number of contending On-Board Units (OBU) increases by applying CSMA medium access control protocol based upon IEEE 802.11p. In a competition-based medium, contention probability becomes high as OBU increases. In order to improve the performance of this medium access layer, the author proposes EDCA which a adaptive adjustment of the Contention Windows (CW) considering traffic density and data type. EDCA applies fixed values of Minimum Contention Window (CWmin) and Maximum Contention Window (CWmax) for each of four kinds of Access Categories (AC) for channel-specific service differentiation. EDCA does not guarantee the channel-specific features and network state whereas it guarantees inter-AC differentiation by classifying into traffic features. Thus it is not possible to actively respond to a contention caused by network congestion occurring in a short moment in channel. As a solution, CWminAS(CWmin Adaptation Scheme) and ACATICT(Adaptive Contention window Adjustment Technique based on Individual Class Traffic) are proposed as active CW control techniques. In previous researches, the contention probabilities for each value of AC were not examined or a single channel based AC value was considered. And the channel-specific demands of IEEE 802.11p and the corresponding contention probabilities were not reflected in the studies. The study considers the collision number of a previous service section and the current network congestion proposes a dynamic control technique ACCW(Adaptive Control of Contention windows in considering the WAVE situation) for CW of the next channel.
Keywords
IEEE 802.11p; EDCA; Contention windows; Access Category;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
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