Enhanced MAC protocol for wireless AD HOC networks using game theory and fuzzy based back off algorithm

Abstract

In ad hoc wireless networks, IEEE 802.11 Distributed Coordinated Function (DCF) determines the idle channel mainly based on the Carrier Sensing Multiple Access mechanism with Collision Avoidance (CSMA-CA) scheme. Contention occurs among the stations willing to transmit at the same time. In order to resolve the contention issues of stations, Backoff (BO) scheme is commonly used in which appropriate waiting time is assigned based on a contention window. In wireless networks, each station executes Binary Exponential Backoff (BEB) retransmission algorithm to resolve the collision and maintain stability of the channel. In BEB algorithm, the size of the Contention Window (CW) is adjusted based on the number of stations. Most of the prior works have modified the BEB algorithm to provide relative priority among two or more traffic classes. However, these works does not address the CW decrement issue explicitly. In IEEE 802.11 back off MAC protocols, the back off interval should be adjusted based on the current traffic load, obtained newlinethroughput, node waiting time, node residual energy and various priorities of traffic classes. However, existing works rarely possess all these parameters. In order to provide solutions to these problems, this thesis proposes a Fuzzy based back off algorithm for multi traffic classes. In this algorithm, the transmitting node uses fuzzy logic technique to compute the back-off interval based on the input variables priority of nodes, queue length, waiting time and residual energy. Based on the outcome of the Fuzzy output, the appropriate back off interval is determined. newline newline