Date Added: Nov 2009
Wireless Sensor Networks (WSN) have a wide range of applications, such as environmental monitoring and precision agriculture. In these applications, WSN are usually tasked to monitor the change of environmental phenomena and report useful information. Environmental phenomena have different levels of spatial, temporal and thematic granularities. The ability of the WSN to observe multi-granularity environmental phenomena depends on the number of sensors deployed in the network, their sensing frequency and their sensing resolution. The sensor nodes in a WSN are usually inexpensive, battery-powered, and have limited processing and communication capabilities. Thus, energy efficiency is the key requirement in the system design of a WSN (Gregory and William, 2000).