Space-free localization for wireless sensor networks based on neighbor topology

The localization of sensor nodes is one of the key issues for sensor network systems. Therefore, to obtain precise location information, several localization systems have been researched. However, they require an arranged space using a large number of anchor nodes whose locations are well known, or they need advance information such as radio conditions in the space. Otherwise, the systems cannot be used for a space that cannot be arranged in advance with suitable conditions for these systems operation. Furthermore, some localizations assume the use of advanced distance measurements, such as TOA and TDOA, to achieve high accuracy in estimating locations, but these advanced distance measurement schemes cannot be used for ordinary sensor node systems. To resolve these problems, we propose Space-Free Localization for wireless sensor networks. Space- Free Localization requires no distance measurement scheme and no advance information on a space; even then it reproduces a geometry nearly similar to the network¿s original geometry without anchor nodes, and it reproduces a geometry with two anchor nodes that is nearly congruent with the original. Furthermore, using just three anchor nodes, it estimates node absolute localization with high accuracy. Therefore, it can be applied to any space and any sensor node. In this paper, the algorithm of Space-Free Localization is described, and its accuracy based on simulation evaluation is shown.