Robust mitigation of selfish misbehavior in wireless networks

Medium access standards rely on complete cooperation of network nodes to provide fair access to common medium. But a selfish user can manipulate its network adapter to gain more access to valuable network resources. Existence of a selfish node in a network can severely degrade performance of well-behaved nodes. As a result, these well-behaved nodes experience drastic throughput drop and large amount of delay. In this paper, a modification to IEEE 802.11 MAC layer is proposed, which reduces the cheating possibility of the selfish node. In the proposed method, next transmitter is selected by current receiver and announced to neighbor nodes. This selection is based on channel usage ratio of neighbor nodes. The specified transmitter starts its transmission immediately after current transmission regardless of its backoff value. Main advantages of the proposed method over existing ones are its capability to mitigate various selfish misbehaviors, robustness against adaptive selfish strategies (a selfish node with ability to change its strategy to deceive security system), and high resiliency against aggressive selfish node (a node with high intention to do selfish behavior). Also, in absence of any selfish node, proposed method does not disturb normal operation of the network. If the proposed method is employed, performance of the network (in terms of throughput of well-behaved nodes and fairness) is approximately not affected in presence of selfish node. This improvement in performance metrics is illustrated by simulating various strategies for selfish node and comparing the results with similar approaches. Copyright (c) 2014 John Wiley & Sons, Ltd.