MAC-layer Acknowledgment as a Tool to Detect Routing Misbehavior

The establishment as well as the survival of mobile ad-hoc networks relies on the cooperation of nodes for performing network operations such as routing and packet forwarding. In these networks, misbehaving nodes can severely degrade network’s performance by not cooperating in networking operations. In this paper, we study the issue of node misbehavior in packet forwarding. To counter this type of misbehavior, we propose a scheme based on the overhearing of MAC-layer acknowledgements. Our main idea centers on the exploitation of the fact that the impartial nodes within the intersection of the transmission zones of the ACK-transmitter and its successor overhear the transmitted acknowledgments by these two nodes. Therefore, if an ACK-transmitter emits an ACK for an in-transit packet, but on a timeout, no ACK is sensed from its successor, acknowledging the receipt of the packet, the misbehavior of the ACK-transmitter will be noticed by the impartial overhearing nodes and reported to the original data packet transmitter, i.e. to the node preceding the ACK-transmitter. We have conducted a series of NS-2 simulation experiments to evaluate the performance of our scheme.