A Watchdog extension scheme considering packet loss for a reputation system in wireless mesh network

Abstract

Most trust and reputation systems in wireless mesh networks are based on the intrusion detection system (IDS) Watchdog. This IDS enables nodes to detect whether their next node on a path flow forwards correctly packets or not by overhearing its transmissions. However, as Watchdog does not consider the packet loss ratio, it can lead to false positives. Indeed, a node can accuse another node of misbehaving whereas in reality it suffers from link loss. In order to overcome this issue, we propose an extension scheme to the Watchdog IDS which enables a node to determine whether it does not overhear its next node due to packet loss issue or due to misbehavior. To reach this goal, we assume that malicious nodes drop both acknowledgements and forwarded packets with different frequencies. Thus, our scheme compares the distribution of a node's acknowledgment with its distribution of forwarded packets of data to detect misbehaving nodes. Furthermore, we extend our scheme so that it enables a node to monitor both its next node and its previous node on a flow path.