System framework for mobile device location

Abstract

A method for estimating the location of a beacon from an ensemble of measurements associated with said beacon, where, contained in each measurement, are GPS data from which surfaces of location may be extracted, together with the ID's of beacons detectable at the point of measurement, is disclosed. The method comprises extracting the canonical set of surfaces of location implicit in each of the associated measurements, and determining the estimate of the location of the beacon as the point for which a weighted sum of the squares of the distances to each of the surfaces so extracted is minimized. A system for the compilation of a database of beacon locations from measurements containing a time-stamped recording of the composite GPS signal (which recording is referred to as a datagram), together with the ID's and associated signal strengths of beacons detectable at the point of measurement, is also disclosed. The system comprises GPS signal processing means for extracting, from each time-stamped datagram, the canonic set of surfaces of location, and beacon location estimation means for estimating the location of a beacon from an ensemble of surfaces of location associated with said beacon.

1 . A method for estimating the location of a beacon, said method comprising:
 incorporating into said beacon, means for measuring and recording a time-stamped composite GPS signal,   periodically measuring and recording time-stamped composite GPS signals;   deriving, from each time-stamped composite GPS signal, the start-of-transmission and the time-of-arrival (TOA) from an identified GPS satellite;   constructing, for each of said identified GPS satellites, a spherical surface of location, centered on said GPS satellites's position at the start-of-transmission, with a radius corresponding to the difference between the time-of-arrival (TOA) and the start-of transmission;   storing said spherical surfaces of location, each with the time stamp of the associated composite GPS signal, in a beacon survey database;   estimating the location of said beacon by determining the point for which the sum of the squares of the distances to each of the ten most recent spherical surfaces of location is minimized.   
     
     
         2 . A method for estimating the location of a beacon said method comprising:
 incorporating into said beacon, means for measuring and recording a time-stamped composite GPS signal;   periodically measuring and recording time-stamped composite GPS signals;   deriving, from each time-stamped composite GPS signal, the start-of-transmission from each of two identified GPS satellites and the difference in the times of arrival (TDOA);   constructing, for each pair of identified GPS satellites, a hyperplane of location, comprised of points for which the difference between the distances from each point to the positions of each of said pair of identified satellites at the start-of-transmission is fixed by the difference in the times of arrival (TDOA);   storing said hyperplanes of location, each with the time stamp of the associated composite GPS signal, in a beacon survey database;   estimating the location of said beacon by determining the point for which the sum of the squares of the distances to each of the ten most recent hyperplanes of location is minimized.   
     
     
         3 . A method for estimating the location of a beacon said method comprising:
 incorporating into said beacon, means for measuring and recording a time-stamped composite GPS signal;   periodically measuring and recording time-stamped composite GPS signals;   extracting a canonical set of surfaces of location from each of the time-stamped composite GPS signals;   storing said surfaces of location, each with the time stamp of the associated composite GPS signal, in a beacon survey database;   estimating, from said surfaces of location, the location of said beacon.   
     
     
         4 . The method of  claim 3 , wherein the estimate of the location of said beacon is determined as the point for which the sum of the squares of the distances to each of the ten most recent surfaces of location is minimized. 
     
     
         5 - 7 . (canceled) 
     
     
         8 . A system for building a database of beacon locations, said system comprising:
 two or more beacons, each with a unique beacon ID, each incorporating means for measuring and recording a time-stamped composite GPS signal;   a survey process, whereby each of said beacons periodically measures and records a time-stamped composite GPS signal;   GPS signal processing means for extracting a canonical set of surfaces of location from said time-stamped composite GPS signals;   surface of location database means for storing surfaces of location, each with the time stamp and the Beacon ID associated with the time-stamped composite GPS signal from which said surface of location was extracted;   beacon location estimation means for estimating, from surfaces of location sharing a common beacon ID, the location of the beacon with said common beacon ID; and   beacon location database means for storing beacon IDs, each with its estimated beacon location.   
     
     
         9 . The system of  claim 8 , wherein the estimate of the location of a beacon is determined as the point for which the sum of the squares of the distances to each of the ten most recent surfaces of location is minimized. 
     
     
         10 . The system of  claim 8 , wherein the GPS signal processing means utilizes a local perfect reference. 
     
     
         11 . The system of  claim 8 , wherein the time-stamped composite GPS signals span multiple cycles of GPS' 50 Hz data overlay. 
     
     
         12 . The method of  claim 3 , wherein said beacon is a Wi-Fi access point. 
     
     
         13 . The method of  claim 3 , wherein said beacon is a Femtocell. 
     
     
         14 . The method of  claim 3 , wherein said beacon is a cardless payment terminal utilizing near field communication technology.