Networked sensors-those that coordinate amongst them-selves to achieve a larger sensing task-will revolutionize information gathering and processing both in urban envi-ronments and in inhospitable terrain. The sheer numbers of these sensors and the expected dynamics in these environ-ments present unique challenges in the design of unattended autonomous sensor networks. These challenges lead us to hypothesize that sensor network coordination applications may need to be structured differently from traditional net-work applications. In particular, we believe that localized algorithms (in which simple local node behavior achieves a desired global objective) may be necessary for sensor net-work coordination. In this paper, we describe localized al-gorithms, and then discuss directed diffusion, a simple com-munication model for describing localized algorithms. 1

The development of techniques for autonomous navigation in real-world environments constitutes one of the major trends in the current research on robotics. An important problem in autonomous navigation is the need to cope with the large amount of uncertainty that is inherent of natural environments. Fuzzy logic has features that make it an adequate tool to address this problem. In this paper, we review some of the possible uses of fuzzy logic in the field of autonomous navigation. We focus on four issues: how to design robust behaviorproducing modules; how to coordinate the activity of several such modules; how to use data from the sensors; and how to integrate high-level reasoning and low-level execution. For each issue, we review some of the proposals in the literature, and discuss the pros and cons of fuzzy logic solutions.

Hierarchies have been widely used in computer networks to help systems scale better by reducing or localizing information propagation thereby reducing message and state overhead in the network. However, simple static configuration techniques widely in use today are not robust enough for dynamic environments. In this thesis, we explore the design and evaluation of distributed automatic hierarchy construction techniques for large dynamic networks. We present a taxonomy of approaches and discuss the various components of automatic hierarchy construction techniques. We then present automatic hierarchy construction algorithms for two different environments. Our first algorithm is intended for the Internet while our second application is in the area of networked embedded devices. These two environments differ in the size of the networks, capabilities of the nodes that form the network as well as the type and frequency of network dynamics. Hence the algorithms designed for these two...