Efficient information discovery and retrieval in wireless ad hoc networks.

摘要

Information, in the form of data and services, pervasively resides in the vast number of nodes in wireless ad hoc networks and sensor networks. To obtain these data and services from the hosting nodes, two procedures, peer discovery and data routing, are executed. Nodes that contain desired data/services are first discovered through peer discovery. After revealing the identity of these peers, data routing transports the data/service from these peers to the requesting node. As nodes in ad hoc networks are generally constrained in resources such as energy and processing power, it is essential to improve the efficiency of information discovery and retrieval.; My thesis is that intelligent models of complex networks are needed to provide a better understanding of the factors that contribute to efficiency, and that analyzing these models can lead to the design of much more efficient information discovery and retrieval schemes.; In the first part of the dissertation, we mathematically model ad hoc networks to find the optimal information discovery parameters such as the total number of searching attempts and the searching radius of each attempt. We first study a general scenario where nodes are uniformly distributed and targets are identical. We then study a special scenario where route caches cause nodes to be non-uniformly distributed and create non-identical targets. In the second part of the dissertation, we develop approaches to improve the efficiency of data routing. For mobile ad hoc networks, we propose a scheme that discovers routes with long lifetimes rather than random routes. For sensor networks, we provide a general data routing model to evaluate different sensor deployment strategies from the perspective of network lifetime and monetary cost. Finally, we look at a concrete peer discovery and service retrieval example by designing a smart document system using a peer-to-peer architecture.; By using the techniques developed in this dissertation, information discovery and retrieval will be much more efficient than what is possible today, enabling the realization of ad hoc networks for important applications, such as real-time audio/video, sensor networking, and peer-aware systems of devices.