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CSMA/CCA: A Modified CSMA/CA Protocol Mitigating the Fairness Problem for IEEE 802.11 DCF


Carrier sense multiple access with collision avoidance (CSMA/CA) has been adopted by the IEEE 802.11 standards for wireless local area networks (WLANs). Using a distributed coordination function (DCF), the CSMA/CA protocol reduces collisions and improves the overall throughput. To mitigate fairness issues arising with CSMA/CA, we develop a modified version that we term CSMA with copying collision avoidance (CSMA/CCA). A station in CSMA/CCA contends for the shared wireless medium by employing a binary exponential backoff similar to CSMA/CA. Different from CSMA/CA, CSMA/CCA copies the contention window (CW) size piggybacked in the MAC header of an overheard data frame within its basic service set (BSS) and updates its backoff counter according to the new CW size. Simulations carried out in several WLAN configurations illustrate that CSMA/CCA improves fairness relative to CSMA/CA and offers considerable advantages for deployment in the 802.11-standard-based WLANs.



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Correspondence to Georgios B Giannakis.

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Open Access This article is distributed under the terms of the Creative Commons Attribution 2.0 International License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Wang, X., Giannakis, G.B. CSMA/CCA: A Modified CSMA/CA Protocol Mitigating the Fairness Problem for IEEE 802.11 DCF. J Wireless Com Network 2006, 039604 (2006).

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