Patent ID: 8886210
Filing Date: 2014-11-11
Classification: G01S,H04W

Abstract:
1. A method comprising: estimating a number of different wireless transmitters in a vicinity of a plurality of known locations based on radio frequency (RF) energy received at the plurality of known locations from the wireless transmitters, wherein the wireless transmitters are at locations which are unknown but which are to be determined; building a received signal strength (RSS) observation vector for each wireless transmitter whose location is to be determined, wherein elements of the RSS observation vector comprise RSS measurements for two or more of the wireless transmitters made at each of the plurality of known locations; and determining permutations of elements of each of the RSS observation vectors that represent RSS measurements from a corresponding wireless transmitter and the corresponding location for each wireless transmitter that together minimize a cost function between the RSS observation vectors and corresponding modeled RSS vectors that are based on a path loss model, wherein the modeled RSS vectors are an estimate of the RSS measurements that would be received at the known locations from a transmitter that transmits with a transmit power according to the path loss model, wherein the permutations of elements of the RSS observation vectors that minimize a mean square error cost function between the RSS observation vectors and the corresponding modeled RSS vectors; and wherein the determining comprises determining permutations of elements of an RSS observation vector r such that: wherein mmse(r) is the minimum mean square error between the RSS observation vectors and modeled RSS vectors over all candidate transmit powers of a given wireless transmitter and candidate locations of the wireless transmitter, u mmse (r) is the wireless transmitter location that minimizes that mean square error, r1 m and r2 m , m=0 . . . , M−1 represent each of M possible permutations of the elements in RSS observation vectors r1 and r2, and m is a permutation index.