Improved backoff algorithm for IEEE 802.11 networks

A mobile ad hoc network (MANET) is a collection of mobile nodes interconnected by wireless media. Several protocols have been proposed to manage multiple access to the shared wireless medium in MANETs, with the IEEE 802.11 being the most implemented protocol. Several approaches have been suggested to improve QoS in the famous IEEE 802.11 MANETs through modifying some of the IEEE 802.11 medium access control (MAC) algorithms, such as the backoff algorithm that is used to control the packets collision aftermath. In this work, an adaptive IEEE 802.11 history based adaptive backoff (HBAB) algorithm to improve QoS is developed and tested in simulations. The protocol modifies the IEEE 80211 backoff algorithm, which is used to control the contention window in the case of collisions, in order to provide a better QoS performance according to the network status and condition. The new algorithm has been tested against the legacy IEEE 802.11 through simulations using QualNet. The tests have shown significant improvements in performance, with up to 33.51% improvement in delay and 7.36% improvement in packet delivery fraction compared to the original IEEE 802.11.