Patent ID: 7835333

Claim:
A method of refining a node position information in a wireless sensor network, comprising: setting, by a first node, an initial position based on a first anchor node; receiving a position refining message from the first anchor node; refining the initial position by measuring a distance to neighboring nodes based on the first anchor node; and notifying the refined position, by switching into a pseudo anchor node based on the refined position information, and broadcasting the refined position information and a pseudo anchor information to the neighboring nodes to notify that the first node is acting as a pseudo anchor node, wherein in the setting of the initial position, the initial position is refined using three other anchor nodes, including anchor nodes within a two-hop distance, or more than the two-hop distance, when the three other anchor nodes do not exist among the neighboring nodes within a 1-hop distance, and wherein the first anchor node obtains a distance function by learning, using the three other anchor nodes and the pseudo anchor node, and the anchor node provides a newly-entering node with the distance function.