Patent Document ID: 9763034
Application ID: 14349903
Patent Status: 1

Claim One:
1. A node positioning method for a wireless network, the network including anchor nodes whose positions are known, and regular nodes whose positions have to be determined, the method comprising: (a) each regular node measuring respective strengths of signals received from neighboring nodes; (b) classifying channels linking any of the neighboring nodes into different channel categories; (c) allocating path loss parameters to each of the channels according to the category the channel is classified into; (d) estimating distances separating said each regular node from each of the neighboring nodes, and respective variances thereof, on the basis of measured strengths of the signals respectively received from the neighboring nodes and the allocated path loss parameters linking said each regular node with each of the neighboring nodes; and (e) estimating the positions of the regular nodes by minimizing a cost function depending upon weighted quadratic differences between distances separating said each regular node from the neighboring nodes and the estimated distances from (d), the weighted quadratic differences being inversely proportional to the respective variances of the estimated distances from (d), wherein said classifying further comprises first classifying all the channels into a line of sight category, and after the first completion of (c), (d), and (e), updating the first classification to the updated classification, in a second attempt, depending upon the estimated positions of the regular nodes step (e), and further comprising calculating, for each channel linking said each regular node and one of the neighboring nodes, an optimization residual indicative of a difference between the estimated distance at (d) and a refined estimated distance calculated from the estimated position of said each regular node at (e), and from the position of the neighboring node, which is a known position if the neighboring node is an anchor node, or is otherwise estimated at (e), wherein if the optimization residual relative to said each channel exceeds a predetermined first threshold, said each channel is classified into a non line of sight category, otherwise said each channel is maintained in the line of sight category, wherein if the optimization residual relative to said each channel exceeds a predetermined second threshold higher than the predetermined first threshold, said each channel is classified into a category of non line of sight with deep attenuation, wherein (b), (c), (d), and (e) are iterated, such that in each iteration after a first completion of (b), (c), (d), and (e): an allocation of path loss parameters in (c) taking into account an updated classification of the channels of (b) in said each iteration, the distances separating each regular node from each of its neighboring nodes and the variances thereof being estimated at (d) in said each iteration on the basis of the path loss parameters allocated at (c) in said each iteration, and the positions of the regular nodes being obtained in said each iteration by minimizing the cost function calculated with the distances and distance variances estimated at (d) in said each iteration.