Wireless Sensor Networks is a fast growing and exciting research area thathas attracted considerable research attention in the recent past. This has beenfueled by the recent tremendous technological advances in the developmentof low-cost sensor devices equipped with wireless network interfaces. Thecreation of large-scale sensor networks interconnecting several hundred to afew thousand sensor nodes opens up several technical challenges and immenseapplication possibilities. Sensor networks find applications spanning severaldomains including military, medical, industrial, and home networks. Wirelesssensor networks have moved from the research domain into the real world withthe commercial availability of sensors with networking capabilities. Companiessuch as Crossbow (www.xbow.com) and Sensoria (www.sensoria.com)have emerged as suppliers of the necessary hardware and software buildingblocks.Some of the key challenges deal with the scalability of network protocolsto large number of nodes, design of simple and efficient protocols for differentnetwork operations, design of power-conserving protocols, design of datahandling techniques including data querying, data mining, data fusion and datadissemination, localization techniques, time synchronization and developmentof exciting new applications that exploit the potential of wireless sensor networks.The purpose of this book is to present a collection of excellent chapters fromleading researchers on various aspects of wireless sensor networks. The submittedarticles were closely reviewed by the editors and their graduate students.The published articles are the revised versions based on these comments. Werealize that technology is so rapidly changing that it is nearly impossible tokeep up with the changes. However, we have endeavored to capture a substantialsubset of the key problems and known solutions to these problems. Someof the chapters present a survey of past research on important problems whileothers deal with specific problems and solutions.The potential audience for this book includes practitioners who are interestedin recent research work that has not appeared in textbooks; those whoare interested in survey articles on specific topics without having to pore overlarger textbooks; and graduate students and others who are starting research inthis field. Our hope is that the reader gains valuable insight into the mainstreamideas behind the technology and is inspired to go forth and innovate new ideasand technologies.