Wireless Sensor Networks Smart Environments: Technologies, Protocols, and Applications ed. D.J. Cook and S.K. Das, John Wiley, New York, B.Devi

Introduction Communication Networks Network Topology Communication Protocols and Routing Power Management Network Structure Historical Development and Standards Wireless sensor networks IEEE 1451 and Smart Sensors Transducers and Physical Transduction Principles Sensors for Smart Environments Commercially Available Wireless Sensor Systems Signal processing and decision making Building and Home Automation Conclusion Synopsis

INTRODUCTION

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 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 study of wireless sensor networks is challenging in that it requires an enormous breadth of knowledge from an enormous variety of disciplines. In this we outline communication networks, wireless sensor networks and smart sensors, physical transduction principles, commercially available wireless sensor systems, signal processing and decision-making, and finally some concepts for home automation.

COMMUNICATION NETWORKS Network Topology

Communication Protocols and Routing The topics of communication protocols and routing are complex and require much study. Some basics useful for understanding sensor nets are presented here. Headers Switching Multiple Access Protocols Flow Control Routing Fixed routing schemes Adaptive routing schemes Deadlock and Livelock Open Systems Interconnection Reference Model (OSI/RM)

Open Systems Interconnection Reference Model (OSI/RM)

Power Management MEMS power generatorMEMS fabrication layout of power generator

Multicast Systems Multicast routing improves efficiency and reduces message path length Network Structure

Historical Development and Standards  Ethernet  Token Ring  Gigabit Ethernet  Client-Server networks  Peer-to-Peer networking  Peer-to-Peer Computing  Wireless Local Area Network  Bluetooth  Home RF

WIRELESS SENSOR NETWORKS Desirable functions for sensor nodes include: Ease of installation Self-identification Self-diagnosis Reliability Time awareness for coordination with other nodes Some software functions and DSP Standard control protocols Network interfaces

Basic architecture of IEEE 1451

A general model of a smart sensor [IEEE 1451 Expo, Oct. 2001]

Transducers and Physical Transduction Principles A transducer is a device that converts energy from one domain to another. In our application, it converts the quantity to be sensed into a useful signal that can be directly measured and processed. Sensory Transducer Sensory transduction may be carried out using physical principles, some of here

Mechanical Sensors include : The Piezoresistive Effect The Piezoelectric Effect Tunneling Sensing Capacitive Sensors

Magnetic and Electromagnetic Sensors include: Magnetic Field Sensors Eddy-Current Sensors Thermal Sensors Thermo-Mechanical Transduction Thermocouples Resonant Temperature Sensors

Sensors for Smart Environments

Commercially Available Wireless Sensor Systems Berkeley Crossbow Motes

Microstrain Wireless Sensors

SIGNAL PROCESSING AND DECISION-MAKING The IEEE 1451 Smart Sensor includes basic blocks for signal conditioning (SC), digital signal processing (DSP). Signal conditioning (SC): SC is performed using electronic circuitry, which may conveniently be built using standard VLSI fabrication techniques in situ with MEMS sensors. Digital signal processing (DSP): Sensor fusion is important in a network of sensors of different modalities. A distributed vehicle/personnel surveillance network might include seismic, acoustic, infrared motion, temperature, and magnetic sensors. The standard DSP tool for combining the information from many sensors

Building and Home Automation Smart Home Networks

CONCLUSION A wireless sensor network (WSN) consists of spatially distributed autonomous sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants. The development of wireless sensor networks was motivated by military applications such as battlefield surveillance. They are now used in many industrial and civilian application areas, including industrial process monitoring and control, machine health monitoring, environment and habitat monitoring, healthcare applications, home automation, and traffic control.