Date Added: Nov 2011
Wireless sensor networks have become a hot research area due to their numerous applications in monitoring inaccessible areas, which are difficult to be monitored by conventional methods. A large number of wireless sensor network based applications are location dependent, where the sensed data is meaningless without accurate location of its origin. Some of these applications require highly accurate location information of sensor nodes. However, in many applications, knowledge of coarse accuracy of sensor node localization is sufficient. In such applications, range-free localization techniques are being used as low cost alternative to the range based localization techniques.