Introduction to sensor networks

Sensors have been widely used for many decades. Types of sensors range from thermostats in homes, to control central-heating systems, through to sensors in cars to warn of a lack of engine oil. Over time there has been a tendency towards an ever-increasing amount of sensors as we seek greater control and convenience. For example, many cars now include sensors to check tyre pressure, windscreen-washer fluid, temperature at multiple points within the cabin, the presence of a passenger of sufficient weight to make the airbag active and so on. In urban areas there is a growing number of closed-circuit television (CCTV) cameras, sensors in buildings to detect occupants and sensors on mass-transit systems to identify users for payment purposes.

Some envisage a world in which sensors are much more widespread. They predict the deployment of additional sensors around cities to measure pollution levels, traffic congestion, temperature and more, or sensors scattered around fields of crops providing information on local growing conditions and allowing precisely tailored application of fertilizers, irrigation, etc. Sensors around the home might detect temperature, light and movement to precisely control the home environment. Sensors in industrial buildings might monitor every aspect of the production process, ensuring a higher-quality output and reduced wastage.

Sensors systems to date have mostly been wired – that is, there is a wire from the sensor to the control system.