Virtual Continuous CWmin Control Scheme of WLAN

Fumihiro INOUE
Fusao NUNO
Takatoshi SUGIYAMA

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E97-A    No.1    pp.40-48
Publication Date: 2014/01/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E97.A.40
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Wideband Systems)
Category: Foundations
CSMA/CA,  IEEE 802.11 DCF,  CWmin control,  fairness,  performance analysis model,  

Full Text: PDF>>
Buy this Article

In this paper, a priority control problem between uplink and downlink flows in IEEE 802.11 wireless LANs is considered. The minimum contention window size (CWmin) has a nonnegative integer value. CWmin control scheme is one of the solutions for priority control to achieve the fairness between links. However, it has the problem that CWmin control scheme cannot achieve precise priority control when the CWmin values become small. As the solution of this problem, this paper proposes a new CWmin control method called a virtual continuous CWmin control (VCCC) scheme. The key concept of this method is that it involves the use of small and large CWmin values probabilistically. The proposed scheme realizes the expected value of CWmin as a nonnegative real number and solves the precise priority control problem. Moreover, we proposed a theoretical analysis model for the proposed VCCC scheme. Computer simulation results show that the proposed scheme improves the throughput performance and achieves fairness between the uplink and the downlink flows in an infrastructure mode of the IEEE 802.11 based wireless LAN. Throughput of the proposed scheme is 31% higher than that of a conventional scheme when the number of wireless stations is 18. The difference between the theoretical analysis results and computer simulation results of the throughput is within 1% when the number of STAs is less than 10.