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. 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, health care applications, home automation, and traffic control.
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 micro controller, and an energy source, usually a battery. The
envisaged size of a single sensor node can vary from shoe box-sized nodes down
to devices the size of grain of dust, although functioning ''motes'' of genuine
microscopic dimensions have yet to be created. The cost of sensor nodes is
similarly variable, ranging from hundreds of dollars to a few cents, depending
on the size of the sensor network and the complexity required of individual
sensor nodes. Size and cost constraints on sensor nodes result in corresponding
constraints on resources such as energy, memory, computational speed and
bandwidth.
A sensor network normally constitutes a Wireless ad-hoc network, meaning
that it each sensor supports a multi-hop routing algorithm (several nodes may
forward data packets to the base station).
In computer science and telecommunications, wireless sensor networks are an
active research area with numerous workshops and conferences arranged each
year.
Typical applications of WSNs include monitoring, tracking, and controlling.
Some of the specific applications are habitat monitoring, object tracking,
nuclear reactor controlling, fire detection, traffic monitoring, etc. In a
typical application, a WSN is scattered in a region where it is meant to
collect data through its sensor nodes.