For fault-tolerant wireless ad-hoc networks, detection and notification of failure of intermediate wireless nodes are critical. Until now, various failure detection and notification methods for recovery such as timeout and watchdog have been proposed for stop failure and Byzantine failure restricted to different data message transmissions. In order to avoid desperate cases such that correctly working wireless intermediate nodes are inappropriately taken away from the wireless multihop transmission routes due to malicious failure notification, this paper proposes a novel cooperative watchdog method. Here, not only the previous-hop intermediate wireless nodes as in the conventional watchdog method but also another neighbor wireless node observe transmissions of both data messages and control messages such as failure notification to detect failure of an intermediate wireless node. This paper also proposes an ad-hoc routing protocol to determine both a sequence of intermediate wireless nodes and additional observing wireless nodes for the cooperative watchdog. Simulation experiments show that the route detection ratio by the proposed routing protocol is a little lower than the well-know ad-hoc routing protocol AODV; however, performance of data message transmissions is never reduced since no additional control messages are usually transmitted in the proposed cooperative watchdog method.
['Norihiro Sota', 'Hiroaki Higaki']
Cooperative Watchdog for Malicious Failure Notification in Wireless Ad-Hoc Networks