An intelligent backoff scheme for IEEE 80211 DCF wireless LANs
Abstract
The wireless MAC Protocol in IEEE 802.11 uses a distributed contention resolution
mechanism for sharing the wireless channel. In this environment, the CSMA/CA scheme
requires nodes contending for access to the channel to wait for a Backoff interval,
randomly selected from a specified range of contention window (CW), before initiating a
transmission. Every time a node packet is involved in a collision, the CW size for that
node is doubled up to a maximum CW, and the new CW is used for the following
transmission attempt. After a successful transmission a node resets its CW to zero. The
random selection of Backoff time and the resetting mechanism causes inefficiency and
unfairness in transmitting nodes. It may also cause unfairness with optimized nodes
obtaining an unfair advantage over well behaved nodes. In this paper, we propose to
replace the random selection of Backoff with an algorithm that will intelligently
determine the Backoff time. The algorithm uses machine learning, Bayesian approach.
We implement our proposed intelligent Backoff algorithm in the Opnet Modular
simulator. Results from simulation experiments reveal that the proposed algorithm
achieves higher throughput than the Binary Exponential Backoff (BEB).
Citation
Masters of science in computer sciencePublisher
University of Nairobi School of Computing and Informatics