This book focuses on theoretical aspects of wireless sensor networks, aiming at providing signal processing and communication perspectives in the design of large-scale sensor networks. Emphasis will be put on the fundamental properties of large scale sensor networks, distributed signal processing and communication algorithms, and novel cross-layer design paradigms for sensor networking. *describes the fundamental properties (key issues as well as challenges) of large-scale wireless sensor networks (wsns). *approaches the hot topic' of wsns from a new angle: covering distributed signal processing and communication algorithms, and novel cross-layer design paradigms for sensor networking. *applies the ideas and illustrations of classical theories and methods of signal processing to an emerging field of applications. *complements existing texts on wireless sensor networks with the infusion of analytical tools that will play important roles in the design of future application-specific wireless sensor networks. *identifies research directions and provides tutorials and bibliographies to facilitate further investigations. *authored by leading international researchers of the field.