International Journal of Computer Applications
In wireless sensor network nodes position estimation in space is known as localization. It plays a critical role in many locations critical applications (like target tracking) where inaccurate location information, can effectively degrade the service performance. The most reliable technique for the localization is GPS but the cost and power requirement makes it's unfeasible for most of the applications. In search of a substitute for GPS, landmark or anchor node (which have perfect information about their positions or coordinates) is used to transmit some reference signal and the other nodes are used some algorithms (trilateration or triangulation etc.) to estimate their position on the basis of reference signal strength (used for distance estimation) and direction (used for angle estimation).