Maintaining Probabilistic Consistency for Frequently Offline Devices in Mobile Ad Hoc Networks

Maintaining cache consistency in mobile environment is an important issue which is extensively studied in the last decade. In mobile ad hoc networks (MANETs), a large number of nonstationary mobile terminals connect with each other through multi-hop unreliable communication channels, coupling with the fact that disconnections from the network are very frequent. Most existing cache consistency strategies assume reliable communication between mobile terminals, which cannot handle frequently offline devices adequately. In this paper, we introduce the probabilistic cache consistency model for applications not requiring strong consistency. Based on this model, a probability consistency strategy (ProP) for frequently offline devices in MANETs is studied. ProP is a randomized pull-based Strategy. It is demostrated to guarantee cache consistency with a high probability. A theoretical model is developed to investigate the performance of the proposed cache consistency strategies, and design guidelines are provided for ProP to choose proper system parameters to achieve probabilistic cache consistency.