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- 저자 : Nurullah Shahin (검색결과 1 건)
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Cognitive Backoff Mechanism for IEEE802.11ax High-Efficiency WLANs
Nurullah Shahin,Rashid Ali,김성원,김영탁 한국통신학회 2019 Journal of communications and networks Vol.21 No.2
Carrier sense multiple access with collision avoidance(CSMA/CA) in current IEEE 802.11 wireless local area networks(WLANs) uses a uniformly distributed binary exponentialbackoff (BEB) mechanism that is mainly based upon exponentialincreases of the contention window (CW) to avoid repeated collisions. After each consecutive collision, the CW is doubled untilit reaches the maximum value. Under dense conditions, however,the blind selection of the CW greatly reduces throughput, whereasunder sparse conditions with smaller number of contending stations,the blind exponential increase of the CW for collision avoidancecauses unnecessarily long delays. Therefore, it fails to achievehigh efficiency in both dense and sparse environments with the currentBEB mechanism. In this paper, we propose a cognitive backoff(CB) mechanism that adaptively determines the CW to provide efficientcollision avoidance with high throughput and low delay underboth dense and sparse conditions. In the proposed CB mechanism,the measured conditional collision probability and the numberof backoff stages determine the CW. A performance analysiswith an event-driven simulator, NS3, reveals that the proposed CBcan achieve higher throughput and lower delay than the BEB, withoutmuch implementation complexity while preserving fairness.
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