Prevention of denial of service attacks and performance enhancement in Mobile Adhoc networks

A mobile ad hoc network is a network without any infrastructure or service access points. In wireless ad hoc networks, the performance of the media access control (MAC) protocol has significant impact on the overall network performance. In contention-based MAC protocols, nodes´ access to the shared channel is not synchronized, and they contend for the channel whenever there are packets in their buffers ready to be sent. To reduce self-contention, Fast-forward mechanism and quick exchange mechanism are being used. But these mechanisms aggravate the fairness problem, because the node that succeeds in the last transmission period will gain access to the shared channel again with much higher probability while other nodes are denied access almost completely. Thus it will lead to denial of service attacks because the last winner is always favored among local contending nodes, a continuously transmitting node can always capture the channel and cause other nodes to back off endlessly. Simulation results also reveal the fairness problem in ad hoc networks refers to the severe degradation in throughput. Here, a DoSP-MAC protocol is proposed to improve the fairness of the network thereby enhance its performance. This can drastically improve the medium utilization.