Wireless sensor networks has grown rapidly as a key area of research and technical as well as commercial development. For more than a decade, there have been tremendous developments in area of electronics and sensors specially. It resulted the rapid deployment of wireless sensor networks as a key solution in variety of applications. Wireless sensor networks are used to monitor a particular area of interest for changes in the parameters like pressure , velocity, displacement etc. Applications of WSNs. Include health, military, environmental, traffic control and many scientific applications. But these have many limitations like power, deployment, routing, security. WSNs. are supposed to be self organised, self healing, self configured and operated even in critical conditions. Many critical conditions like avalanche, fire, earthquake need these easy configured networks to solve the problem. But deployment of nodes in such application is also very tedious because nodes are to be deployed in very large quantity and to be scattered over a geographic area from a distance. Though WSNs. have many interesting area for researchers and developers but one of the major area among them is coverage. Coverage can be defined as a measure of how comfortably and for how long the sensors are able to observe the physical space. In this paper, we are surveying the existing solutions and their utilization to the coverage in WSNs.
