Patent ID: 8462663

Claim:
A method of determining the physical position of a movable node in a network, comprising: sending a first message from the movable node to at least a first node; receiving the first message in the first node and sending a second message from the first node in reply; receiving the second message in the movable node and determining in the movable node the distance between the movable node and the first node using the time between sending the first message and receiving the second message; receiving the second message in a second node and sending a third message from the second node in reply; receiving the third message in the movable node and determining in the movable node the distance between the movable node and the second node using the time between sending the first message and receiving the third message; receiving the third message in a third node and sending a fourth message from the third node in reply; receiving the fourth message in the movable node and determining in the movable node the distance between the movable node and the third node using the time between sending the first message and receiving the fourth message; determining the location of the moveable node from the determined distances between the first moveable node and known locations of the first, second and third nodes.