定位机制研究(Localization Distance Measurements The distances from an unknown node to several references constrain the presence of this node,which is the basic idea of the so called multilateration. -A to-be located node (node 0)measures the distances from itself to three references (nodes 1,2,3).Obviously,node 0 should locate at the intersection of three circles centered at each reference position.The result of trilateration is unique as long as three references are non-linear. (a) (b) Fig.3.Trilateration.(a)Measuring distance to 3 reference nodes. (b)Ranging circles.定位机制研究（Localization） • Distance Measurements – The distances from an unknown node to several references constrain the presence of this node, which is the basic idea of the so called multilateration. – A to-be located node (node 0) measures the distances from itself to three references (nodes 1, 2, 3). Obviously, node 0 should locate at the intersection of three circles centered at each reference position. The result of trilateration is unique as long as three references are non-linear