Increasing Performance in IEEE 802.11 for High Traffic by MIDD Backoff Algorithm

Abstract

The main mechanism in IEEE 802.11 to access the medium is distributed coordination function (DCF) as a random access scheme based on carrier sense multiple access with collision avoidance. DCF describes two access techniques for packet transmission, namely basic access mechanism and request to send/clear to send mechanism. A new backoff algorithm has been proposed here for high load traffic in IEEE 802.11. The proposed algorithm is called maximum increment double decrement (MIDD) which gradually reduces the size of windows in a successful transmission and maximizes it in an unsuccessful one. Meanwhile, a mathematical analysis has been developed for MIDD algorithm based on studying Markov chain and performance analysis of the suggested algorithm. Results from this analytical model of MIDD algorithm are compared with those of IEEE 802.11 and double increase, double decrease algorithm, while the results of the throughput analysis have been examined on these three algorithms. The obtained results demonstrate that a great increase of windows size in the unsuccessful transmission as well as a small decrease of windows size in the successful transmission are beneficial for the high traffic conditions. However, a small increase of the windows size in the unsuccessful transmission and a large decrease of it in the successful transmission are ideal for the low traffic case.