Towards a collision-free WLAN: dynamic parameter adjustment in CSMA/E2CA

Barceló Vicens, Jaume; Bellalta, Boris; Cano Bastidas, Cristina; Sfairopoulou, Anna; Oliver Riera, Miquel; Verma, Kshitiz

doi:http://dx.doi.org/10.1155/2011/708617

Towards a collision-free WLAN: dynamic parameter adjustment in CSMA/E2CA

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Barcelo J, Bellalta B, Cano C, Sfairopoulou A, Oliver M, Verma K. Towards a collision-free WLAN: dynamic parameter adjustment in CSMA/E2CA. EURASIP Journal on Wireless Communications and Networking. 2011;2011(708617):1-11. DOI: 10.1155/2011/708617.

Abstract

Carrier sense multiple access with enhanced collision avoidance (CSMA/ECA) is a distributed MAC protocol that allows collisionfree/naccess to the medium in WLANs. The only difference between CSMA/ECA and the well-known CSMA/CA is that the former/nuses a deterministic backoff after successful transmissions. Collision-free operation is reached after a transient state during which/nsome collisions may occur. This paper shows that the duration of the transient state can be shortened by appropriately setting the/ncontention parameters. Standard absorbing Markov chain theory is used to describe the behaviour of the system in the transient/nstate and to predict the expected number of slots to reach the collision-free operation. The paper also introduces CSMA/E2CA,/nin which a deterministic backoff is used two consecutive times after a successful transmission. CSMA/E2CA converges quicker to/ncollision-free operation and delivers higher performance than CSMA/ECA, specially in harsh wireless scenarios with high frameerror/nrates. The last part of the paper addresses scenarios with a large number of contenders. We suggest dynamic parameter/nadjustment techniques to accommodate a varying (and potentially high) number of contenders. The effectiveness of these/nadjustments in preventing collisions is validated by means of simulation