Introduction To Wireless Sensor Networks

Wireless Sensor Networks A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations.

Wireless Sensor Networks The development of wireless sensor networks was originally motivated by military applications such as battlefield surveillance. However, wireless sensor networks are now used in many civilian application areas, including environment and habitat monitoring, healthcare applications, home automation, and traffic control.

Sensor Node Networks of typically small, battery-powered, wireless devices. On-board processing, Communication, and Sensing capabilities. Storage Sensors Processor Radio P O W E R WSN device schematics

Sensor Node In addition to one or more sensors, each node in a sensor network is typically equipped with a radio transceiver or other wireless communications device, a small microcontroller, and an energy source, usually a battery. Storage Sensors Processor Radio WSN device schematics P O W E R

Sensor Node

Sensor Network Antenna Interface electronics, radio and microcontroller Server Soil moisture Communications probe barrier Mote Sensor field Gateway Internet

Computer Revolution Original IBM PC (1981) 4.77 MHz 16-256 KB RAM 160 KB Floppies ~ $6K (today) ~ 64 W 25 lb, 19.5 x 5.5 x 16 inch MICAZ Mote (2005) 4 MHz 128 KB RAM 512 KB Flash ~ $35 ~14 mw 0.5 oz, 2.25 x 1.25 x 0.25 inch

Sensor Network Server Sensor Watershed field Gateway Internet

Network Model for WSN A wireless sensor network consists of hundreds or thousands of low cost nodes which could either have a fixed location or randomly deployed to monitor the environment. The flowing of data ends at special nodes called base stations (sometimes they are also referred to as sinks).

Network Model for WSN A base station links the sensor network to another network (like a gateway) to disseminate the data sensed for further processing. Base stations have enhanced capabilities over simple sensor nodes since they must do complex data processing.

Network Model for WSN This justifies the fact that bases stations have workstation/laptop class processors, and of course enough memory, energy, storage and computational power to perform their tasks well.

Usage of Sensor Networks Environmental Observation: Sensor networks can be used to monitor environmental changes. An example could be water pollution detection in a lake that is located near a factory that uses chemical substances. Sensor nodes could be randomly deployed in unknown and hostile areas and relay the exact origin of a pollutant. Other examples include forest fire detection, air pollution and rainfall observation in agriculture.

Usage of Sensor Networks Military Monitoring: Military uses sensor networks for battlefield surveillance; sensors could monitor vehicular traffic, track the position of the enemy.

Usage of Sensor Networks Building Monitoring: Sensors can also be used in large buildings or factories monitoring climate changes. Thermostats and temperature sensor nodes are deployed all over the building s area. In addition, sensors could be used to monitor vibration that could damage the structure of a building.

Usage of Sensor Networks Healthcare: Sensors can be used in biomedical applications to improve the quality of the provided care. Sensors are implanted in the human body to monitor medical problems like cancer and help patients maintain their health.