Patent Document ID: 20180132064
Application ID: 15696506
Patent Flag: 0

Claim One:
1. A method of determining a position of at least one transceiver node with respect to an at least two-dimensional coordinate space, the method comprising: providing, at respective known spatial positions, at least four anchor nodes; in performing a positioning sequence, anchor node by anchor node transmitting respective positioning frames suitable for reception by the at least one transceiver node and by at least one other of the anchor nodes, wherein the positioning sequence comprises a given anchor node transmitting a respective positioning frame for reception by at least that anchor node, which is the next anchor node in the positioning sequence, and by the at least one transceiver node, the next anchor node in the positioning sequence receiving the positioning frame from that anchor node, which is the preceding anchor node in the positioning sequence, and ascertaining a time of reception of the positioning frame, and the next anchor node ascertaining, after transmitting its respective positioning frame, a respective forwarding time span (T Fi ) between the time of reception of the positioning frame from the preceding anchor node and the time of transmitting the its respective positioning frame; the at least one transceiver node receiving the positioning frames transmitted by the anchor nodes and ascertaining respective times of reception for each of the received positioning frames; providing to a solver stage for numerically solving a non-linear system of equations the following parameters: sets of coordinates of the known positions of the anchor nodes performing the positioning sequence, a set of times of flight (t tof(i-1)i ) between pairs of respective anchor nodes of neighboring ranks ((i−1) and i) in the positioning sequence, using their known positions and a known propagation speed of the positioning frames, the respective times of reception of the respective positioning frames at the respective anchor nodes performing the positioning sequence, the respective forwarding time spans (T Fi ) ascertained by the respective anchor nodes performing the positioning sequence, and the respective times of reception of the respective positioning frames from the anchor nodes at the at least one transceiver node; performing the solver stage, using the provided parameters, for determining the coordinates (x s , y s , z s ) of the respective transceiver node and the time t s of transmission of the first positioning frame by the anchor node of first rank in the positioning sequence by numerically solving a non-linear system of at least five equations, at least four equations of the nonlinear system using the relation t n = t s + 1 c ( x n - x s ) 2 + ( y n - y s ) 2 + ( z n - z s ) 2 + t sn , wherein t n is a time of reception of the respective positioning frame from a given anchor node of rank n in the positioning sequence at the at least one transceiver node, x n , y n , z n are the coordinates of the position of anchor node of rank n in the positioning sequence, 
 t sn =Σ i=2 n ( t tof(i-1)i +T Fi ), t s , to be determined by the solver engine, is a time of transmission of the positioning frame by the anchor node having the first rank in the positioning sequence, and x s , y s , z s , to be determined by the solver engine, are the coordinates of the transceiver node; performing a positioning extension sequence including: providing the determined time t s of transmission of the first positioning frame by the anchor node of first rank in the positioning sequence to the anchor nodes involved in the positioning sequence; after the positioning sequence has been performed by the anchor nodes, the at least one transceiver node broadcasting a broadcast positioning frame for reception by all anchor nodes; the anchor nodes receiving the broadcast positioning frame from the transceiver node and ascertaining a respective time of its reception, using the time t s of transmission of the first positioning frame by the anchor node of first rank in the positioning sequence as a common reference point in time; providing to a second solver stage for numerically solving a non-linear system of equations using the following parameters: the sets of coordinates of the known positions of the anchor nodes performing the positioning sequence, the respective times of reception of the broadcast positioning frame at the respective anchor nodes, and performing a second solver stage using the provided parameters, for determining the coordinates (x s , y s , z s ) of the transceiver node and the time t ST of transmission of the broadcast positioning frame by the at least one transceiver node, by numerically solving a second non-linear system of at least five equations, at least four equations of the nonlinear system using the relation t rn = t ST + 1 c ( x n - x s ) 2 + ( y n - y s ) 2 + ( z n - z s ) 2 , wherein t rn is a time of reception of the broadcast positioning frame at a given anchor node n, x n , y n , z n are the coordinates of the position of anchor node n, t ST , to be determined by the second solver engine, is a time of transmission of the broadcast positioning frame by the transceiver node, and x s , y s , z s , to be determined by the second solver engine, are the coordinates of the transceiver node.