Enhanced Collision Resolution and Throughput Analysis for the 802.11 Distributed Coordination Function

Abstract

The IEEE 802 standards rely on the distributed coordination function (DCF) as the fundamental medium access control method. DCF uses the binary exponential backoff (BEB) algorithm to regulate channel access. The backoff time determined by BEB depends on a contention window (CW) whose size is doubled if a station suffers a collision and reset to its minimum value after a successful transmission. Doubling the size of CW reduces channel access time, which decreases the throughput.Resetting it to its minimum value harms fairness since the station will have a better chance of accessing the channel compared to stations that suffered a collision. We propose an algorithm that addresses collisions without instantly increasing the CW size. Our algorithm aims to reduce the collision probability without affecting the channel access time and delay. We present extensive simulations for fixed and mobile scenarios. The results show that, on average, our algorithm outperforms BEB in terms of throughput and fairness. Compared to exponential increase exponential decrease (EIED), our algorithm improves, on average, throughput and delay performance. We also propose analytical models for BEB, EIED, and our algorithm. Our models extend Bianchi’s popular Markov chain-based model by using a collision probability that is dependent on the station transmission history. Our models provide a better estimation of the probability that a station transmits in a random slot time, which allows a more accurate throughput analysis. Using our models, we show that both the saturation throughput and maximum throughput of our algorithm are higher than those of BEB and EIED.

Description

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

Keywords

Distributed coordination function, IEEE 802.11, Medium access control, Collision resolution, Delay, Throughput, Fairness, Binary exponential backoff.

Citation

Kobbaey, T., Hamzaoui, R., Ahmad, S., Al-Fayoumi, M. and Thomos, N. (2021) Enhanced collision resolution and throughput analysis for the 802.11 distributed coordination function. International Journal of Communication Systems,

Rights

Research Institute