Timing-based detection of packet forwarding in MANETs

In mobile ad hoc networks (MANETs), timing information is easily available due to the use of a shared medium, even when the traffic is encrypted. This paper addresses how such timing information can be used for detecting packet forwarding activities in MANETs. Our results depend in part on the previous results on unidirectional flow detection. We first provide further analysis for the unidirectional flow detector proposed in, under the independent Poisson chaff assumption. Regardless of the fraction of chaff, it is shown that flows can be detected consistently, and the false alarm probability decays exponentially fast as the sample size grows. Then, we consider the detection of packet forwarding. Our approach is based on the duality between packet forwarding and unidirectional flows. We propose a threshold-based detector and conclude that its performance characteristic is the same with that of the unidirectional flow detector.