Cluster-based data transmission protocol in delay-tolerant mobile networks

In this article, we investigate a distributed clustering scheme and a cluster-based routing protocol for delay-tolerant mobile networks. The basic idea is to distributively group mobile nodes that have similar mobility pattern into a cluster, which can then interchangeably share their resources such as buffer space for overhead reduction and load balancing. Due to the lack of continuous communications and possible errors in the estimation of nodal contact probability, convergence and stability become major challenges in such cluster formation. In our algorithm, an exponentially weighted moving average (EWMA) scheme is employed for on-line updating the nodal contact probability, with its mean proven to converge to the true contact probability. Based on the local information, a set of functions including Sync(), Leave(), and Join() is devised for cluster formation and gateway selection. Finally, the gateway nodes exchange network information and perform routing.