Date Added: Aug 2012
Wireless Sensor Networks (WSNs) are composed of many homogeneous or heterogeneous sensor nodes with limited resources. A sensor node is comprised of three components: a sensor, a processor and a wireless communication device. These sensor nodes dispersed throughout it to monitor, collect, and transmit data. The sensors are inexpensive, simple, and their power source is irreplaceable. Knowing the sensors power levels cannot be restored, many protocols have been developed to make collecting, receiving and transferring data more energy efficient.