Tracking Message Spread in Mobile Delay Tolerant Networks
Delay Tolerant Network is considered under two message forwarding schemes ÃƒÂ¢Ã¢â€šÂ¬Ã¢â‚¬Å“ a non-replicative direct delivery scheme and a replicative epidemic routing scheme. The objective is to track the degree of spread of a message in the network. Such estimation can be used for on-line control of message dissemination. With a homogeneous mobility model with pairwise i.i.d. exponential intermeeting times, we rigorously derive the system dynamic and measurement equations for optimal tracking by a Kalman filter. Moreover, we provide a framework for tracking a large class of processes that can be modeled as density-dependent Markov chains. The same filter is applied with a heterogeneous mobility, where the aggregate inter-meeting times exhibit a power law with exponential tail as in real-world mobility traces, and show that the performance of the filter is comparable to that with homogeneous mobility.