To appear in Smart Environments: Technologies, Protocols, and Applications ed. D.J. Cook and S.K. Das, John Wiley, New York, 2004. Wireless Sensor Networks 1 F. L. LEWIS Associate Director for Research Head, Advanced Controls, Sensors, and MEMS Group Automation and Robotics Research Institute The University of Texas at Arlington 7300 Jack Newell Blvd. S Ft. Worth, Texas 76118-7115 email lewis@uta.edu, http://arri.uta.edu/acs 2.1. INTRODUCTION Smart environments represent the next evolutionary development step in building, utilities, industrial, home, shipboard, and transportation systems automation. Like any sentient organism, the smart environment relies first and foremost on sensory data from the real world. Sensory data comes from multiple sensors of different modalities in distributed locations. The smart environment needs information about its surroundings as well as about its internal workings; this is captured in biological systems by the distinction between exteroceptors and proprioceptors. PDA BSC (Base Station Controller, Preprocessing) BST Wireless Sensor Machine Monitoring Medical Monitoring Wireless Sensor Wireless Data Collection Networks Wireless (Wi-Fi 802.11 2.4GHz BlueTooth Cellular Network, - CDMA, GSM) Printer Wireland (Ethernet WLAN, Optical) Animal Monitoring Vehicle Monitoring Online monitoring Server transmitter Any where, any time to access Notebook Cellular Phone PC Ship Monitoring Wireless Sensor Networks Roving Human monitor Data Distribution Network Management Center (Database large storage, analysis) Data Acquisition Network The challenges in the hierarchy of: detecting the relevant quantities, monitoring and collecting the data, assessing and evaluating the information, formulating meaningful user displays, and performing decision-making and alarm functions are enormous. The information needed by smart environments is provided by Distributed Wireless Sensor Networks, which are responsible for sensing as well as for the first stages of the processing hierarchy. The importance of sensor networks is highlighted by the number of recent funding initiatives, including the DARPA SENSIT program, military programs, and NSF Program Announcements. The figure shows the complexity of wireless sensor networks, which generally consist of a data acquisition network and a data distribution network, monitored and controlled by a management center. The plethora of available technologies makes even the selection of 1 This research was supported by ARO Research Grant DAAD 19-02-1-0366 1