US20090303113A1 - Methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system - Google Patents

Methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system Download PDF

Info

Publication number
US20090303113A1
US20090303113A1 US12/479,727 US47972709A US2009303113A1 US 20090303113 A1 US20090303113 A1 US 20090303113A1 US 47972709 A US47972709 A US 47972709A US 2009303113 A1 US2009303113 A1 US 2009303113A1
Authority
US
United States
Prior art keywords
wlan
location
satellite
estimate
measurements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/479,727
Inventor
Farshid Alizadeh-Shabdiz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Skyhook Wireless Inc
Original Assignee
Skyhook Wireless Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=41398570&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=US20090303113(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Skyhook Wireless Inc filed Critical Skyhook Wireless Inc
Priority to US12/479,727 priority Critical patent/US20090303113A1/en
Assigned to SKYHOOK WIRELESS, INC. reassignment SKYHOOK WIRELESS, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ALIZADEH-SHABDIZ, FARSHID
Publication of US20090303113A1 publication Critical patent/US20090303113A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W64/00Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42Determining position
    • G01S19/48Determining position by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42Determining position
    • G01S19/45Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
    • G01S19/46Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being of a radio-wave signal type
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13Receivers
    • G01S19/31Acquisition or tracking of other signals for positioning
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/14Determining absolute distances from a plurality of spaced points of known location
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13Receivers
    • G01S19/34Power consumption

Definitions

  • the disclosure generally relates to hybrid positioning systems and, more specifically, to methods of integrating wireless local area network (WLAN)-based positioning system (WLAN-PS) and satellite-based positioning system (SPS) to improve accuracy of location estimates, increase availability of the positioning service to more users, reduce power consumption, and also to improve estimation of the expected error in a user's position estimate.
  • WLAN wireless local area network
  • SPS satellite-based positioning system
  • Location-based services are an emerging area of mobile applications that leverage the ability of new devices to calculate their current geographic positions and report them to a user or to a service. Examples of these services range from obtaining local weather, traffic updates, and driving directions to child trackers, buddy finders, and urban concierge services. These new location-sensitive devices rely on a variety of technologies that all use the same general concept. By measuring radio signals originating from known reference points, these devices can mathematically calculate the user's position relative to these reference points. Each of these approaches has its strengths and weaknesses, depending upon the nature of the signals and measurements, and the positioning algorithms employed.
  • GPS Global Positioning System
  • Cellular carriers have used signals originating from and received at cell towers to determine a user's or a mobile device's location.
  • Assisted GPS is another model that combines both GPS and cellular tower techniques to estimate the locations of mobile users who may be indoors and must cope with attenuation of GPS signals on account of sky blockage.
  • the cellular network attempts to help a GPS receiver improve its signal reception by transmitting information about the satellite positions, their clock offsets, a precise estimate of the current time, and a rough location of the user based on the location of cell towers. No distinction is made in what follows between GPS and AGPS.
  • Satellite-based Positioning System SPS
  • GLONASS Globalstar Satellite-based Positioning System
  • Galileo European system
  • SPS Satellite-based Positioning System
  • GPS, GLONASS and Galileo are all based on the same basic idea of trilateration, i.e., estimating a position on the basis of measurements of ranges to the satellites whose positions are known.
  • the satellites transmit the values of certain parameters which allow the receiver to compute the satellite position at a specific instant.
  • the ranges to satellites from a receiver are measured in terms of the transit times of the signals.
  • range measurements can contain a common bias due to the lack of synchronization between the satellite and receiver (user device) clocks, and are referred to as pseudoranges.
  • the lack of synchronization between the satellite clock and the receiver (user device) clock results in a difference between the receiver clock and the satellite clock, which is referred to as internal SPS receiver clock bias or receiver clock bias, here.
  • internal SPS receiver clock bias or receiver clock bias In order to estimate a three dimensional position there is a need for four satellites to estimate receiver clock bias along with three dimensional measurements. Additional measurements from each satellite correspond to pseudorange rates in the form of Doppler frequency. References below to raw SPS measurements are intended generally to mean pseudoranges and Doppler frequency measurements.
  • References to SPS data are intended generally to mean data broadcast by the satellites.
  • References to an SPS equation are intended to mean a mathematical equation relating the measurements and data from a satellite to the position and velocity of an SPS receiver.
  • WLAN-based positioning is a technology which uses WLAN access points to determine the location of mobile users.
  • Metro-wide WLAN-based positioning systems have been explored by a several research labs. The most important research efforts in this area have been conducted by the PlaceLab (www.placelab.com, a project sponsored by Microsoft and Intel); the University of California, San Diego ActiveCampus project (ActiveCampus—Sustaining Educational Communities through Mobile Technology, technical report #CS2002-0714); and the MIT campus-wide location system.
  • PlaceLab www.placelab.com, a project sponsored by Microsoft and Intel
  • ActiveCampus ActiveCampus—Sustaining Educational Communities through Mobile Technology, technical report #CS2002-0714
  • MIT campus-wide location system There is only one commercial metropolitan WLAN-based positioning system in the market at the time of this writing, and it is referred to herein as the WPS (WiFi positioning system) product of Skyhook Wireless, Inc. (www.skyhookwireless.com).
  • FIG. 1 depicts a conventional WLAN-based positioning system based on WiFi signals.
  • the positioning system includes positioning software 103 that resides on a mobile or user device 101 . Throughout a particular target geographical area, there are a plurality of fixed wireless access points 102 that transmit information using control/common channel signals. The device 101 monitors these transmissions. Each access point contains a unique hardware identifier known as a MAC address.
  • the client positioning software 103 receives transmissions from the 802.11 access points in its range and calculates the geographic location of the computing device using the characteristics of the radio signals. Those characteristics include the MAC addresses, the unique identifiers of the 802.11 access points, the Time of Arrival (TOA) of the signals, and the signal strength at the client device 101 .
  • TOA Time of Arrival
  • the client software 103 compares the observed 802.11 access points with those in its reference database 104 of access points.
  • This reference database 104 may or may not reside in the device 101 .
  • the reference database 104 contains the calculated geographic locations and power profiles of all access points the system has collected. A power profile may be generated from a collection of measurements of the signal power or signal TOA at various locations.
  • the client software 103 uses these known locations or power profiles to calculate the position of the user device 101 relative to the known positions of the access points 102 and determines the device's 101 absolute geographic coordinates in the form of latitude and longitude or latitude, longitude, and altitude. These readings then can be fed to location-based applications such as friend finders, local search web sites, fleet management systems, and an E911 service.
  • raw WLAN measurements from an access point are generally intended to mean received signal strength (RSS) and/or times of arrival (TOAs) and/or time differences of arrival (TDOAs).
  • RSS received signal strength
  • TOAs times of arrival
  • TDOAs time differences of arrival
  • References to data are generally intended to mean the MAC address, one or more record(s) of it, one or more power profile(s), and other attributes based on previous measurements of that access point.
  • References to a WLAN-PS equation are intended to mean a mathematical equation relating the WLAN-PS measurements and data to the location of the mobile device.
  • a WLAN-based positioning systems can be used indoor or outdoor. The only requirement is presence of WLAN access points in the vicinity of the user.
  • the WLAN-based position systems can be leveraged using existing off-the-shelf WLAN cards without any modification other than to employ logic to estimate position.
  • FIG. 2 illustrates a conventional way of integrating WLAN-PS and SPS, which consists of a WLAN-PS 201 and a SPS 206 , and a location combining logic 210 .
  • WLAN-PS 201 and SPS 206 are stand-alone systems and each can operate independently of the other system. Thus the result of each system can be calculated independent of the other system.
  • the estimated location along with the expected error estimation of each system can be fed to the location combining logic 210 .
  • the expected error estimation is also referred to as HPE (horizontal positioning error) herein.
  • HPE horizontal positioning error
  • the nominal rate of location update of SPS 206 and WLAN-PS 201 is once a second.
  • the location combining logic 210 combines location estimates calculated in the same second by both systems.
  • WLAN-PS 201 is a conventional system which estimates the location of a mobile device by using WLAN access points.
  • WLAN-PS 201 can include a scanner of WLAN APs 202 , a device to select WLAN APs 203 , a trilateration module 204 , and HPE estimation device 205 .
  • WLAN Scanner 202 detects WLAN APs surrounding the mobile device by detecting the received power (RSS, received signal strength) and/or time of arrival (TOA) of the signal.
  • RSS received power
  • TOA time of arrival
  • Different methods can be used to detect WLAN APs including active scanning, passive scanning, or combination of passive and active scanning.
  • the select WLAN APs device 203 selects the best set of WLAN APs to estimate location of the mobile device. For example, if ten WLAN APs are detected and one AP is located in Chicago and the others are located in Boston, without any other information, the Boston APs are selected. This is an indication that Chicago AP has been moved to Boston. In the conventional system the best set of WLAN APs is selected based on geographical distribution of WLAN APs in addition to corresponding parameters of WLAN APs, including received signal strength, signal to noise ration, and the probability of being moved.
  • Trilateration module 204 uses WLAN APs and corresponding measurements and characteristics to estimate location of the mobile device. Received signal strength or TOA measurements from WLAN AP are used to estimate distance of the mobile device to the WLAN AP. The aggregation of distance estimates from different WLAN APs with known location is used to calculate location of the mobile device. Trilateration 204 also can use a method which is called nearest neighbor, in which a location with a power profile similar or closest to the power reading of the mobile device is reported as the final location of the mobile device. The power profile of each WLAN AP or entire coverage area can be found in the calibration phase of the system by detailed survey of the coverage area.
  • HPE estimation device 205 is the module which estimates the expected error of the position estimate of the mobile device.
  • the HPE, or Horizontal Positioning Error is calculated based on previously scanned APs and their characteristics and also characteristics of the received signal, as it was explained in co-pending Skyhook Wireless application Ser. No. 11/625,450 entitled “System and Method for Estimating Positioning Error Within a WLAN Based Positioning System,” the entire disclosure of which is hereby incorporated by reference.
  • SPS system 206 consists of a satellite signal receiver and measurement device 207 , trilateration device 208 , and the SPS HPE estimation module 209 .
  • the satellite signal receiver and measurement device 207 receives signals from the satellites in view of the device, decodes the received signal, and measures the satellite parameters from each satellite.
  • the measurements can include pseudorange, carrier frequency, and Doppler frequency.
  • the trilateration device 208 uses measurements from at least four satellites and location of the satellites in view to estimate location of the user device, velocity, and direction of travel of the mobile device.
  • HPE estimation device 209 estimates the expected error of the estimated location.
  • the HPE estimation device 209 is conventional and calculates expected error based on geometry of the satellites and signal quality of the received signal from satellites, for example, DOP (dilution of precision), and C/N (carrier to noise ratio).
  • Location combining logic 210 receives location and HPE estimates calculated for almost the same second from WLAN-PS 201 and SPS 206 . In other words, measurements and estimations which are made at the same time are compared and combined. Practically, measurements and estimations within one second can be considered the same time.
  • the location combining logic 210 of the user device reports one estimated location by selecting one of them or linearly combining them. For example, location combining logic might select one of the estimated locations provided by WLAN-PS 201 or SPS 206 based on reported expected error or HPE, or it might report weighted average of estimated locations by both systems according to the HPE.
  • the method of determining an expected error in a location determination of a WLAN and satellite enabled device can include determining a WLAN location estimate and an expected error estimate for the WLAN location estimate, obtaining measurements from at least two satellites, and determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.
  • consistent measurements between the WLAN location estimate and the satellite positioning system measurements can result in a lower expected error in the location determination.
  • inconsistent measurements between the WLAN location estimate and the satellite positioning system measurements can result in a higher expected error in the location determination.
  • consistency of the measurements can include the distance between the WLAN positioning system location estimation and a region of possible solutions provided by the satellite positioning system measurements.
  • the consistency of the internal SPS receiver clock for the WLAN based position estimate can be used as an indication of consistency between the WLAN based position estimate and the satellite measurements.
  • the method can include determining a WLAN based location estimate and an expected error estimate for the WLAN location estimate, determining a satellite based location estimate and an expected error estimate for the satellite based location estimate, determining the expected error of the location determination by evaluating the consistency of the satellite positioning system location estimate to the WLAN positioning system location estimation.
  • the position estimate with the lower expected error can be selected as the location of the WLAN and satellite enabled device.
  • the method can include determining the expected error of the location determination by comparing the WLAN location estimate and the satellite positioning system location estimate.
  • consistent measurements between the WLAN location estimate and the satellite positioning system location estimate can result in a lower expected error in the location determination.
  • inconsistent measurements between the WLAN location estimate and the satellite positioning system location estimate can result in a higher expected error in the location determination.
  • the consistency of the estimates can include the distance between the satellite positioning system location estimate and the WLAN positioning system location estimation.
  • the method can include the internal SPS receiver clock for the WLAN based position estimate is used as an indication of consistency between the WLAN based position estimate and the satellite positioning system location.
  • Some embodiments relate to a system for increasing the accuracy of a WLAN based position estimate using satellite positioning information.
  • the system can include a positioning module including a WLAN module for receiving information from one or more WLAN access points to calculate a WLAN location estimate, a satellite positioning module for obtaining satellite information from at least two different satellites, and logic located in the positioning module for determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.
  • Some embodiments relate to a system for increasing the accuracy of a WLAN based position estimate using satellite positioning information.
  • the system can include a positioning module including a WLAN module for receiving information from one or more WLAN access points and to calculate a WLAN position estimate, a satellite positioning module for obtaining satellite information from at least four different satellites to calculate a satellite position estimate, and logic located in the positioning module for determining the expected error of the location determination by evaluating the consistency of the satellite positioning system location estimate to the WLAN positioning system location estimation.
  • FIG. 1 illustrates a high-level architecture of a WLAN positing system
  • FIG. 2 illustrates a system for a conventional way of integrating WLAN-PS and SPS
  • FIG. 3 illustrates a system for providing a WLAN-PS and SPS integrated solution according to some embodiments of the disclosed subject matter
  • FIG. 4 illustrates an example of selecting a solution between possible WLAN-PS solutions using raw SPS measurements from two satellites according to some embodiments of the disclosed subject matter
  • FIG. 5 illustrates a system for integrating WLAN-PS and SPS in which raw SPS measurements are provided to WLAN-PS to select the best solution according to some embodiments of the disclosed subject matter;
  • FIG. 6 illustrates an example of selecting a solution between possible WLAN-PS solutions based on SPS possible solutions according to some embodiments of the disclosed subject matter
  • FIG. 7 illustrates an example of selecting the best set of WLAN APs based on raw SPS measurements according to some embodiments of the disclosed subject matter
  • FIG. 8 illustrates a system for integrating WLAN-PS and SPS and using raw SPS measurements from two or more satellites to select a set of WLAN APs in WLAN-PS according to some embodiments of the disclosed subject matter
  • FIG. 9 illustrates a system for examining the location estimate and uncertainty provided by WLAN-PS against SPS in order to find the best estimate of the location of a mobile device according to some embodiments of the disclosed subject matter
  • FIG. 10 illustrates a system for examining the location estimate and uncertainty provided by WLAN-PS against SPS in order to find the best estimate of the location of a mobile device by using the grid method according to some embodiments of the disclosed subject matter;
  • FIG. 11 illustrates a system for integrating WLAN-PS and SPS, in which raw SPS measurements are used to refine WLAN-PS location estimate according to some embodiments of the disclosed subject matter
  • FIG. 12 illustrates a system for integrating WLAN-PS and SPS, in which as WLAN-PS location estimate is provided as initial location estimate according to some embodiments of the disclosed subject matter;
  • FIG. 13 illustrates an example for increasing accuracy of the estimation of expected error by using SPS and WLAN-PS information according to some embodiments of the disclosed subject matter
  • FIG. 14 illustrates a system for increasing accuracy of the estimation of expected error by using SPS and WLAN-PS information according to some embodiments of the disclosed subject matter
  • FIG. 15 illustrates a system for stationary user detection based on two or more satellites according to some embodiments of the disclosed subject matter.
  • Embodiments of the disclosed subject matter provide a method of integrating a WLAN-based positioning system (WLAN-PS) and a satellite-based positioning system (SPS) to create a hybrid positioning system.
  • WLAN-PS WLAN-based positioning system
  • SPS satellite-based positioning system
  • An integrated or hybrid system refers to a system which combines the measurements from one or more systems to improve the accuracy of the positioning and velocity and bearing estimates and the accuracy of expected error estimate, and to reduce consumed power as compared to each individual system working independently.
  • the method of integrating a WLAN-PS and SPS to create a hybrid positioning system can add raw SPS measurements as another input to WLAN-PS and WLAN-PS final estimations as another input to SPS.
  • Raw SPS measurements from two or more satellites can assist the WLAN-PS to increase the accuracy of position estimate, HPE, and stationary user detection.
  • WLAN-PS initial position estimate and other estimations also can help SPS to reduce time to first fix (TTFF) and power consumption.
  • a hybrid positioning system also can reduce power consumption compared to WLAN-PS and SPS working independently by deactivating WLAN-PS or SPS when they are not adding value in terms of increasing accuracy or other estimations.
  • FIG. 3 illustrates a block diagram of the hybrid system of a WLAN-PS 301 and a SPS 306 .
  • SPS 306 is an off-the-shelf, conventional satellite positioning device which consists of the same devices as SPS 206 in FIG. 2 , with addition of an output 311 and an input 312 from the WLAN-PS (discussed in more detail herein).
  • Satellite receiver and measurement device 207 is part of every conventional SPS receiver 306 , and raw SPS measurements are an essential part of the SPS measurement. However, here the raw SPS measurements are used outside the SPS 306 , as is shown by output 311 .
  • Not all the commercial SPS receivers expose the raw SPS measurements to devices outside SPS 306 .
  • Star III GPS manufactured by SiRF Technology, Inc. provides raw SPS measurements as part of its standard interface. However there are some other GPS receivers that do not provide such measurements.
  • the SPS receiver 306 is modified to permit access to the raw SPS measurements.
  • the WLAN-PS 301 functions in a similar manner as the WLAN-PS 201 shown in FIG. 2 except that it is configured to receive raw SPS measurements 311 .
  • the integration of the raw SPS measurement with WLAN-PS 301 changes the design of WLAN APs selection device 303 , trilateration device 304 , and HPE estimation device 305 .
  • the WLAN-PS 301 can take advantage of the raw SPS measurements when at least two satellites are acquired, even without any fix or solution from the SPS 306 .
  • the disclosed method integrates a WLAN-based positioning system (WLAN-PS) and a satellite-based positioning system (SPS) in which the WLAN-PS provides a set of possible locations of a mobile device, and among the possible locations, the one which fits the SPS measurements the best is selected as the final position estimate.
  • WLAN-PS WLAN-based positioning system
  • SPS satellite-based positioning system
  • This embodiment also can provide a method to integrate WLAN-based positioning system (WLAN-PS) and satellite-based positioning system (SPS) in which the WLAN-PS provides a set of possible locations for the mobile device, and the possible locations are weighted according to their distance to a plurality of possible SPS device location solutions.
  • WLAN-PS provides a set of possible locations for the mobile device
  • SPS satellite-based positioning system
  • weights are assigned to WLAN-PS possible solutions according how well they correspond to the satellite measurements.
  • various algorithms can be used to combine or select WLAN-PS possible locations. For example, the final reported location can be weighted by an average of all possible locations, low weight locations can be removed from the weighted average, or only the highest weighted location can be reported. Selection can be a special case of weighting, in which the respective weights are zero and one.
  • WLAN-PS can detect tens of WLAN APs in a given location.
  • the detected WLAN APs may form more than one cluster.
  • a cluster is defined as a set of APs in the coverage area of each other. If the coverage of a WLAN AP is not known, a nominal coverage can be considered. Nominal coverage or typical coverage of a WLAN AP is found statistically by measuring coverage for thousands of WLAN APs, and it is reported numbers between 100 m and 250 m at the time of writing this document.
  • the detected WLAN APs can be considered as two clusters with a size of ten and five, respectively.
  • Conventional positioning algorithms would select the cluster with a higher number of APs: the cluster of ten APs. Under the conventional approach, the location would be somewhere in the high-rise building.
  • raw SPS measurements from two or more satellites are considered with the cluster information, even with no location estimate from SPS, the raw SPS measurements can be used to select the appropriate cluster of WLAN APs from the plurality of clusters.
  • the cluster of five WLAN APs might be selected as the closest cluster to the location of the mobile device, because it also satisfies the SPS equations.
  • SPS measurements also can be used to assign a weight to the clusters of five and ten APs according to their estimated distance from possible SPS solutions.
  • logic can be used to combine the estimation results of clusters and report only one location. For example, the weighted average of estimation results of clusters, estimations of the cluster with maximum weight, or average of estimation of clusters with higher weights can be reported as final estimation results.
  • the first step is detecting WLAN access points, which will be used as reference points to locate the user device.
  • WLAN access points are randomly distributed, and they also might move over time. Therefore, the WLAN positioning system applies a clustering algorithm to identify all the clusters of WLAN access points that are detected by the end user.
  • a cluster of WLAN access points is a set of WLAN access points which are in the coverage area of each other. WLAN access points which are farther than a normal coverage of an access point from the cluster are considered as a new cluster.
  • a user detects four access points and three of them are located in Boston and one of them in Seattle. Therefore, they form two clusters: one in Boston with three WLAN access points and one in Seattle with one WLAN access point.
  • Each cluster of WLAN access point can result to a separate location in a WLAN positioning system.
  • the mobile device also acquires signals from two or more satellites, the satellite measurements can be used to select the cluster of WLAN access points or reject clusters of WLAN access points.
  • Two or more satellite measurements provide a set of solutions in a form of a region (volume, surface or a curve).
  • the proximity of possible WPS solutions to SPS possible solutions can be criteria to weight, select, or reject WPS solutions. In other words, the closer the WLAN-PS solution to the SPS solutions, the higher the quality of the WLAN-PS solution.
  • FIG. 4 shows a WLAN-PS 401 , which consists of five WLAN access points 404 .
  • the WLAN access points form two clusters in this example, a first cluster 402 and a second cluster 403 .
  • Each cluster can be used to estimate the location of the user device. If the user device acquires a signal from at least two satellites 405 , the possible solutions of the two or more satellites 406 can be used to select or eliminate some clusters. In this example, possible solution of the two or more satellites is shown as a band 406 .
  • Cluster 402 is closer to the possible satellite solutions band 406 than cluster 403 . Therefore, cluster 402 can be selected and cluster 403 can be rejected.
  • FIG. 5 illustrates block diagram of integrated solution of SPS and WLAN-PS.
  • SPS 506 can be a standard, off-the-shelf device, but it has to be able to provide raw SPS measurements as discussed in FIG. 3 .
  • the raw SPS measurements 311 are directed to WLAN APs 503 and trilateration device 504 .
  • the WLAN APs selection devices 503 receives the data from WLAN scanner 202 as an input.
  • the WLAN APs selection device 503 clusters WLAN APs based on the distance between the access points.
  • the WLAN APs selection device 503 not only identifies clusters, but also selects a different set of WLAN APs for each cluster. Each different cluster may result in a different location estimate. All of the different sets of clusters can be used in the trilateration device 504 and may result in a different location estimate.
  • the location estimates based on clusters can be weighted according to the cluster distance from the SPS possible solutions or can be selected according to their cluster distance from SPS possible solutions. A cluster can be assigned a high weight if it is considered close (at a small distance) from the satellite distance solution.
  • a cluster can be assigned a low weight if it is considered far (at a large distance) from the satellite distance solution, for example, if it is located on the order of 100 or 1,000 meters away from the satellite distance solution.
  • the SPS solutions can be found as follows. In each satellite measurement, there are generally four unknowns coordinates of location of the mobile device, (x,y,z) and internal clock bias of SPS receiver.
  • the raw SPS measurements from two or more satellites can be used to eliminate the internal clock bias of the SPS receiver from the equations. In this case, the result is going to be a function of coordinates of the location of the user device, (x,y,z), which can be written as a general form as follows:
  • This function can represent an area, a surface, or a curve based on number of satellites. Therefore, raw SPS measurements from two or more satellites can result in a set of possible solutions, even without having a final location estimate.
  • the distance between the different solutions of WLAN-PS and possible solutions of SPS can be used as criteria to weigh each WLAN-PS solution. After assigning a weight to each WLAN-PS possible solution, logic can be used to combine the solution or select the solution from the possible solutions.
  • the consistency between the SPS measurements and the locations provided by the WLAN-PS can be used as an indication of distance between the locations provided by the WLAN-PS and location of the mobile device.
  • the location of the user device can be calculated by (1) using the possible WLAN-PS locations as rough estimates of the location of the user device (i.e., using each possible WLAN-PS location as the x,y,z) and (2) calculating the final unknown, internal satellite receiver clock bias, for each WLAN-PS location estimate using the measurements from each satellite.
  • the consistency between the calculated internal satellite receiver clock biases (calculated for each satellite in view) for each WLAN location estimate can be used as an indicator of distance between WLAN-PS's location estimate and the mobile device actual location.
  • WLAN-PS estimates will have consistent receiver clock bias estimates, i.e., when that WLAN-PS estimated location is used as the x,y,z location, for each satellite, the receiver clock bias will be substantially the same, for example, within about 10% of each other. However, if the WLAN-PS location is a poor estimate of the location of the user device, the WLAN-PS location will produce varied satellite receiver clock bias estimates for each satellite, for example, the receiver clock biases will vary by at more than 10%.
  • FIG. 6 shows SPS solution in form of a region 606 and a WLAN positioning system 601 , in which WLAN access points 604 form a first cluster 602 and a second cluster 603 .
  • the mobile device acquisition of two or more satellites 605 also can result in a set of possible satellite device solutions 606 .
  • the consistency between the SPS solutions 606 and WLAN-PS solutions 602 is used to select the best solution, which is the 602 solution of WLAN-PS in this example.
  • the consistency between the SPS and WLAN-PS means both of them report the same location as part of their solutions or that the final estimated position is one of the solutions of both systems.
  • a cluster of APs can be weighted according to their distance to possible solutions of SPS.
  • Another embodiment of the disclosed subject matter provides a method to weigh WLAN access points by using raw SPS measurements. Selecting the best set of WLAN access points to estimate end user's location by using raw SPS measurements can be a specific case of assigning a weight to WLAN APs. In addition to other criteria used to weight or select the best set of WLAN access points to estimate the mobile device location, raw SPS measurements can be used or combined with the other criteria. Other criteria and weights are weight based on received signal strength or weight based on round trip time of received signal.
  • the WLAN-PS uses WLAN APs and their characteristics to estimate the location of a mobile device.
  • the characteristics of a WLAN AP might include, but are not limited to, received signal strength (RSS), location or estimation of location, signal to noise ratio, and time of arrival (TOA).
  • RSS received signal strength
  • TOA time of arrival
  • Raw SPS measurements from two or more satellites are used to calculate an indication of distance between location (or estimated location) of WLAN APs and actual location of the mobile device. This indication of distance can be used to select the best set of WLAN APs to estimate location of the mobile device, or the indicator of distance can be used to weight WLAN APs according to their distance from the device location.
  • the raw SPS measurements from at least two satellites can be used in this process, with or without having a location estimate from SPS.
  • the distance is considered far if the distance is more than an order of magnitude larger than the coverage area of the WLAN AP.
  • a distance is considered close or not far is the distance is within an order of magnitude of the coverage area of the WLAN AP.
  • WLAN APs that are considered far can be eliminated from the positioning calculation.
  • FIG. 7 shows an example of an integrated solution of WLAN-PS and SPS, in which the mobile device detects five WLAN access points 702 and has acquired a signal and raw measurements from two satellites 704 .
  • the WLAN access points are randomly spread around the mobile device, and distance between WLAN access points 702 and possible solutions of two satellites 703 can be used as an indication of distance between WLAN access point and actual location of the mobile device.
  • a region of possible SPS solutions 703 is calculated using measurements from two satellites.
  • the distance between the WLAN access point 702 and SPS possible solution 703 is used as an indicator of distance between WLAN access point and actual location of the mobile device.
  • WLAN access point 702 - 1 all the WLAN access points 702 - 1 are very close to SPS possible solutions 703 , but one WLAN access point 702 - 2 is not. Therefore, the longer distance between WLAN access point 702 - 2 and possible SPS solutions 703 is an indicator of a larger distance between WLAN access point 702 - 2 and the location of the mobile device compared to other detected WLAN access points 702 - 1 .
  • WLAN access point 702 - 2 can be weighted according to its distance to SPS possible solutions, or it can be removed from the set of APs to calculate the mobile device location.
  • FIG. 8 illustrates WLAN-PS 801 and SPS 806 integrated solution, in which all the modules are the same as FIG. 2 , except for selecting WLAN APs 803 .
  • Selecting WLAN APs 803 also receives raw SPS measurements 311 as an input. These raw measurements are used to estimate the distance between the location (or estimated location) of WLAN APs and the location of the mobile device.
  • the consistency between the raw SPS measurements and the WLAN APs can be used as an indication of distance between the location of WLAN APs and the location of the mobile device.
  • the consistency can be calculated by (1) using the WLAN AP's location as an estimation of the location of the mobile device and (2) calculating the receiver clock bias for each WLAN AP location based on the measurements from each satellite.
  • the consistency between calculated receiver clock biases can be used as an indicator of distance between WLAN APs location and the mobile device's actual location.
  • Ci clock bias which is found for each satellite measurement
  • Consistency of Ci can be measured with different mathematical approaches, like standard deviation of Ci, or mean square error of Ci estimation as follows:
  • the value of MSE can be used as an indicator of the consistency of the Ci samples. Therefore, the location of all the detected WLAN APs can be examined with SPS raw measurements, and the consistency of Ci can be used as an indicator of their distance to the mobile device location. This indicator can be used with other AP parameters to weight, select, or remove an AP in the process of calculating the mobile device location.
  • a system and method in which the WLAN-PS provides a region in which a possible location solution resides, and within the provided region, the final location estimate of the mobile device is selected based on SPS measurements from two or more satellites.
  • FIG. 9 shows an integrated WLAN-PS and SPS, in which WLAN-PS 901 provides an estimate of the location of the mobile device with some uncertainty 903 .
  • the uncertainty 903 can be the expected error of WLAN-PS.
  • the mobile device also acquires signal from two or more satellites 902 . Using all the points within the uncertainty area 903 reported by WLAN-PS, the location 904 which fits the satellite measurements the best is selected as the best estimate of location of the mobile device.
  • the best point which fits satellite solutions within that region can be found by dividing the uncertainty area 903 to small grids and evaluating each grid point as is shown in FIG. 10 .
  • the distance between grid lines can be based on the required accuracy of location estimation and the quality of the SPS measurements. The higher the accuracy requirement and the quality of the SPS measurements, the smaller the distance between the grid lines can be and the more accurate the location estimate.
  • the grid lines can be between about 5 meters and about 100 meters apart, preferably at about 10 meters apart.
  • the number of SPS satellites 902 can be two or more. This system or method can be used in cases where the SPS cannot determine the location of the mobile device by itself but where the WLAN-PS possible solution 903 can be examined with the SPS information to select as the best location 904 the one that is most consistent with the SPS pseudorange equations.
  • FIG. 11 shows an integrated solution of WLAN-PS 1101 and SPS 1106 , in which final location estimate provided by WLAN-PS is refined by using SPS measurements 311 from two or more satellites.
  • a new module, refining module 1111 is added to conventional WLAN-PS, which receives WLAN-PS trilateration results, the corresponding uncertainty of those measurements, and SPS measurements from two or more satellites. Using this information, the refining module 1111 reports the location estimate of the mobile device.
  • the WLAN-PS provides a sphere of possible location solutions to refining module 1111 .
  • the size of the sphere corresponds to the uncertainty of the location estimate of WLAN-PS (expected error), which can be calculated for each position estimate in some embodiments, or the nominal value of uncertainty of WLAN-PS can be used.
  • expected error the location estimate of WLAN-PS
  • nominal value of uncertainty of WLAN-PS can be used.
  • median error of Skyhook Wireless WLAN-PS is about 30 m, which can be used as nominal value of WLAN-PS error.
  • SPS measurements from two or more satellites can be used to find a point within the specified region by WLAN-PS, which satisfies the SPS measurements the best.
  • the satellite equation for each satellite is written as follows:
  • (x, y, z) is location of the mobile device
  • b is denoted for the internal clock bias of SPS receiver.
  • Any point within the specified region by WLAN-PS provides an estimate for the location of the mobile device, (x, y, z), and internal clock bias is calculated for each acquired satellite. Because all the measurements are done at almost the same time by the same SPS receiver, the internal clock bias of SPS receiver should be almost the same for all the SPS measurements. Therefore, as discussed previously, the consistency between receiver clock biases of SPS receiver calculated from different acquired satellites can show the distance between location estimate (x,y,z) and actual location of the mobile device. The consistency of the calculated internal clock of SPS receiver can be measured by calculating the standard deviation of the receiver clock bias measurements.
  • the SPS equations are examined at each grid point.
  • the grid point which provides the most consistent receiver clock bias for all the acquired satellites is the best location estimate of the mobile device.
  • Another embodiment of the invention provides a method to reduce acquisition time of SPS by providing a position estimate of WLAN-PS as an initial position to SPS.
  • Providing an initial position by WLAN-PS can reduce the acquisition period of the SPS and therefore reduces time to first fix of SPS.
  • Satellite positioning systems already provide a method to receive an initial position, and how they use the provided initial position inside SPS is generally known.
  • the present system uses a WLAN-PS location estimate as a source of initial position for the satellite positioning system. Because the location of SPS satellites are known at any time, knowledge of a rough location of the mobile device can help the SPS to reduce the set of satellites it searches for to the set of satellites actually visible to the device, instead of all of the satellites, thereby reducing searching time.
  • FIG. 12 illustrates a WLAN-PS 201 and SPS 1203 , in which WLAN-PS provides an initial position 1211 to the SPS system.
  • the estimated location of the mobile device 1211 by the WLAN-PS 201 can be provided as initial position to SPS 1202 . Knowing the initial position of the mobile device can assist SPS 1202 to select the best set of the satellites to search and reduce time to fix a location of the device.
  • the WLAN-PS and the SPS can work independently and provide estimates of attributes of a mobile device, including location estimation, expected error in the location estimation, velocity, and bearing estimation.
  • WLAN-PS has a much shorter time to first fix (TTFF) than SPS, the estimated location by WLAN-PS can be provided to SPS as initial position of the mobile device, reducing the time required to find location.
  • TTFF time to first fix
  • the receipt of an initial position is a standard practice in SPS, and most of the SPS receivers provide a method to receive the initial position.
  • the WLAN-PS is used as the source of providing the initial position to SPS.
  • Another embodiment of the invention provides a method to increase the accuracy of the expected error of location estimate of the integrated location solution of SPS and WLAN-PS and compare the error to the error location result for each individual system.
  • the expected error estimation provides an uncertainty area around the estimated location. If estimated location of WLAN-PS and SPS are within the uncertainty area of each other, the uncertainty area is reduced based on distance between estimated locations from both systems. If estimated locations of WLAN-PS and SPS are not within the uncertainty area of each other, the uncertainty area is increased based on distance between estimated locations from both systems. If only one of the estimated locations of WLAN-PS and SPS falls inside the uncertainty area of the other system, the uncertainty area can be reduced or increased based on quality of estimated error from each system.
  • the estimated error of location estimate normally reports the 95% confidence interval, but it can report any other confidence interval as well.
  • Another embodiment of the invention provides a method to increase the accuracy of the expected error of a location estimate of the integrated location solution of SPS and WLAN-PS.
  • the WLAN-PS provides a location estimate and the SPS acquires at least two satellites.
  • the expected error estimation provides an uncertainty area around the estimated WLAN-PS location.
  • the consistency between the estimated location of WLAN-PS and raw SPS measurements is used as criteria to reduce or increase the expected error estimate. If estimated location estimate of WLAN-PS and raw SPS measurements are consistent, the uncertainty area is reduced based on distance between WLAN-PS estimated location from SPS possible solutions. If the estimated location of WLAN-PS and raw SPS measurements are not consistent, the uncertainty area is increased based on distance between WLAN-PS estimated locations from SPS possible solutions.
  • FIG. 13 illustrates WLAN-PS location estimation 1301 and WLAN-PS expected error of estimation 1303 and also SPS location estimation 1302 and SPS expected error of estimation 1304 .
  • the reported uncertainty by each system is the expected error of position estimate.
  • the SPS and WLAN-PS each provides a location estimate and also an estimate of the expected error in that location estimation.
  • the expected errors of the location estimate provided by both systems are combined in order to provide a better estimate of the error of the location estimation. For example, if each system provides an area around the reported location as an uncertainty of the estimated location ( 1303 and 1304 ), the integrated system considers the overlap of the uncertainty areas 1305 and also the distance between estimated locations 1306 to estimate the uncertainty of the final location estimate. The greater the distance between the estimated locations by SPS and WLAN-PS is, the higher the expected error of location estimation. In another implementation, the system can select the location estimate with the lowest uncertainty as the final location estimate.
  • FIG. 14 illustrates a block diagram of integrated WLAN-PS and SPS system, in which the expected error of each system is calculated using conventional method and the results are provided to integrated error estimation system device 1411 .
  • the integrated error estimation 1411 calculates the final expected error by considering the consistency between the reported locations by WLAN-PS and SPS. The consistency can also be determined by comparing the receiver clock bias, as discussed previously.
  • the SPS can detect that the mobile device is stationary. In general, it takes measurements from four SPS satellites to estimate the velocity or speed of a mobile device. The present method and system can determine if the mobile device is stationary by using the measurements from as few as two satellites by examining the consistency of the Doppler frequency measurements from the two or more satellites. If the device is stationary, the Doppler measurements from SPS must be fully accounted for by satellite motion relative to initial position of the device and the frequency offset of the receiver clock. The receiver clock offset can be estimated, given the Doppler measurements from two or more satellites. The hypothesis that the user is stationary is based on the size of the residuals after the estimated receiver frequency bias is substituted in the SPS Doppler equations.
  • the hybrid system can cause the WLAN-PS to respond differently than when the device is in motion. For example, WLAN-PS can save power by updating the location less often, for example, once a minute.
  • the WLAN-PS can consider all of the detected WLAN access points over the time interval that the mobile device is stationary and use the collective information to estimate an improved location of the mobile device. This is because the WLAN-PS can obtain a better estimate of the received signal strength from an access point and better mitigate power fluctuation due to multi-path when user is stationary.
  • Multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths and causes power to fluctuate, and it is a known phenomena by experts in the radio propagation field.
  • FIG. 15 illustrates stationary user detection based on two or more satellites. If the mobile device 1503 detects two or more satellites, 1501 , 1502 one can determine that the mobile device is stationary or moving from Doppler measurement of the received signal from satellites.
  • the first step is finding a rough location of the mobile device 1503 , which can be calculated by WLAN-PS.
  • This rough estimate of location of the mobile device can be provided by other positioning technologies as well.
  • the rough estimation of the location of the mobile device can have an error of up to about a couple of kilometers although accuracy of rough estimation of location by WLAN-PS is maximum couple of hundred meters.
  • the mobile device can acquire a signal from at least two satellites, which are shown with satellites 1501 and 1502 in FIG. 15 .
  • the mobile device also knows the velocity of the satellites at the exact time of signal acquisition. In other words, if the mobile device 1503 acquires a signal from satellites 1501 and 1502 at time t, the velocity of the satellites at time t also is known by the mobile device.
  • the mobile device 1503 can determine the velocity of the acquired satellites 1501 and 1502 by decoding the messages received from the satellites, as all satellite broadcasts its velocity at any moment of time.
  • the mobile device can also receive satellite velocity from other sources, for example, a cellular network.
  • Velocity is a vector with magnitude and direction, and it was shown with velocity of V 1 and V 2 for satellites 1501 and 1502 , respectively.
  • Doppler frequency due to satellite movement is calculated based on velocity.
  • the simplified equation to find Doppler frequency for each satellite is as follows:
  • the ⁇ is wavelength of SPS radio wave and it is known for any SPS system, and f d is the Doppler frequency.
  • the mobile device measures the frequency of the received signal from each satellite. Since the transmit frequency of each satellite is known, the mobile device can measure the difference between the frequency of the received signal and the transmitted signal. The difference between received and transmitted frequency are denoted by f m1 and f m2 for satellites 1501 and 1502 , respectively.
  • the measured frequency from each satellite is calculated as follows:
  • the angles ⁇ 1 and ⁇ 2 are between the velocity vector of the satellites and the lines connecting the mobile device to the satellites for satellite 1501 and 1502 , respectively.
  • the mobile device can calculate the angles based on the devices location, the location of the satellites, and the velocity vector of the satellites. If the mobile device is stationary, the above equations are rewritten as follows:
  • f 0 The only unknown for the mobile device in these equations is f 0 , and it can be found from each satellite equation independently. If the mobile device is stationary, the values of f 0 from all the acquired satellites are going to be the same. In other words, if the values of f 0 from equations for all the acquired satellites are not the same, the mobile device is not stationary.
  • WLAN APs are stationary radio transceivers with relatively small coverage, which are surveyed for positioning purposes.
  • one of the characteristics associated with the WLAN APs can be characteristics of the environment.
  • the detected WLAN access points by a mobile device are used collectively to determine the environment in which a mobile device is operating.
  • the environmental characteristics can be considered as attributes of WLAN access points, for example, density of buildings near the AP height of buildings near AP, and whether the AP is in an urban canyon, urban, or suburban location.
  • the data on the environmental characteristics of the access points can reside in the reference database of the access points and can be obtained there by the user device.
  • the granularity of the area which is characterized by WLAN access points, can be different, and it can be as small as a building or as big as a neighborhood.
  • Environmental information can be used by SPS, WLAN-PS, and also an integrated solution of both systems to adjust the systems approach to position acquisition and/or for power management. For example, knowledge of the fact that a mobile device is in an urban canyon environment might cause the hybrid system to rely on WLAN-PS alone, while in a suburban environment, SPS might be considered as the primary source of estimation of position and other attributes of the mobile device.
  • Another embodiment of the disclosed subject matter and system provides a method to maintain the stability of the internal clock of a SPS receiver by using the WLAN APs. This can be accomplished by measuring known time intervals of the signal transmitted by a WLAN device equipped with a stable clock. Maintaining the internal clock stability of a SPS receiver is important for position determination. For example, it can help in acquiring satellite signals faster, being able to operate at lower power, and also providing a fix (location estimation) with fewer satellites.
  • a WLAN standard defines constant time intervals, including, but not limited to, some packet headers, some fields in some packets, as in WLAN 802 . 11 standard DIFS (DCF Inter Frame Space), SIFS (Short Inter Frame Space), or slot duration, and a mobile device can use these known time intervals to measure its internal clock bias over time and maintain its stability.
  • WLAN access points with different clock stability.
  • data identifying the access points which are equipped with a stable clock can be considered as part of characteristics of the WLAN AP and/or the characteristics can reside in the access point data base and can be obtained from there.
  • the WLAN positioning system can provide clock updates to the WLAN-enabled SPS receiver. Every SPS receiver is equipped with an internal oscillator in order to maintain its indication of GPS clock information. However, because these oscillators are imperfect at maintaining an exact measurement of time, the clocks internal to the SPS receivers drift. This clock drift can cause position estimation errors.
  • the WLAN-PS providing the correct GPS clock information to the SPS system, the WLAN positioning system facilitates avoiding such position estimation errors.
  • the SPS receivers are able to maintain a highly accurate measure of the GPS clock information, they can operate at relatively lower signal to noise ratio (SNR) values in the position estimation calculations. Maintaining SPS timing by SPS receiver reduces time uncertainty of received signals from satellites. Therefore, it is easier to extract signal from noise, and SPS receiver can detect weaker signal and operate in harsher locations in terms of SPS signal. Thus aspects of the method allow SPS receivers to operate in areas having less that ideal SPS signal conditions.
  • SNR signal to noise ratio
  • WLAN municipal networks are city wide WLAN networks which are installed in city by city officials or under their supervision to provide wireless connection using WLAN technology. Aspects of this method and system of improving SPS receiver position estimation accuracy by using WLAN municipal network data consists of the following items:
  • the municipal WLAN access points should be synchronized with the GPS clock.
  • WLAN access points of a municipal network can be synchronized with the GPS clock by using one of the following methods as examples: (1) use of SPS enabled WLAN APs where each WLAN AP in a municipal network can be equipped with a device which extracts the GPS clock information from GPS radio signals, (2) use of centralized clock distribution entity synchronized where the GPS clock information can be extracted at one place and then distributed to all the WLAN APs in the municipal network, and (3) use of a high quality oscillator in WLAN AP. An oscillator is used to measure time and maintain synchronization with the GPS clock.
  • the single module that extracts the GPS clock information (herein “Clock Distribution Entity”) is the only unit and only place which extracts the GPS clock information and then provides timing to all the WLAN access points in the network.
  • the SPS receiver can use the WLAN receiver to extract timing information from the signals received from WLAN access points of WLAN municipal networks. While the idea of providing initial timing to SPS receiver has been explained for WLAN municipal networks, it can be applied to any WLAN network which is synchronized to a GPS clock.

Abstract

This disclosure describes methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system. In some embodiments, the method of determining an expected error in a location determination of a WLAN and satellite enabled device can include determining a WLAN location estimate and an expected error estimate for the WLAN location estimate, obtaining measurements from at least two satellites, and determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/059,580, filed on Jun. 6, 2008, entitled Integrated WLAN-based and Satellite-based Positioning System, which is herein incorporated by reference in its entirety.
  • This application is related to the following references:
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “Method and System for Determining Location Using a Hybrid Satellite and WLAN Positioning System by Selecting the Best WLAN-PS Solution;”
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “Systems and methods for Using Environmental Information in a Hybrid Positioning System;”
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “Systems and Methods for Maintaining Clock Bias Accuracy in a Hybrid Positioning System;”
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “System and Method for Refining a WLAN-PS Estimated Location Using Satellite Measurements in a Hybrid Positioning System;”
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “Method and System for Determining Position Using a WLAN-PS Estimated Position as an Initial Position in a Hybrid Positioning System;”
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “Methods and Systems for Stationary User Detection in a Hybrid Positioning System;” and
  • U.S. patent application Ser. No. (TBA), filed concurrently herewith and entitled “System and Methodfor Using a Satellite Positioning System to Filter WLAN Access Points in a Hybrid Positioning System.”
  • BACKGROUND
  • 1. Field
  • The disclosure generally relates to hybrid positioning systems and, more specifically, to methods of integrating wireless local area network (WLAN)-based positioning system (WLAN-PS) and satellite-based positioning system (SPS) to improve accuracy of location estimates, increase availability of the positioning service to more users, reduce power consumption, and also to improve estimation of the expected error in a user's position estimate.
  • 2. Description of Related Art
  • In recent years the number of mobile computing devices has increased dramatically, creating the need for more advanced mobile and wireless services. Mobile email, walkie-talkie services, multi-player gaming, and call-following are examples of how new applications are emerging for mobile devices. In addition, users are beginning to demand/seek applications that not only utilize their current location but also share that location information with others. Parents wish to keep track of their children, supervisors need to track the locations of the company's delivery vehicles, and a business traveler looks to find the nearest pharmacy to pick up a prescription. All of these examples require an individual to know his own current location or the location of someone else. To date, we all rely on asking for directions, calling someone to ask their whereabouts or having workers check-in from time to time to report their positions.
  • Location-based services are an emerging area of mobile applications that leverage the ability of new devices to calculate their current geographic positions and report them to a user or to a service. Examples of these services range from obtaining local weather, traffic updates, and driving directions to child trackers, buddy finders, and urban concierge services. These new location-sensitive devices rely on a variety of technologies that all use the same general concept. By measuring radio signals originating from known reference points, these devices can mathematically calculate the user's position relative to these reference points. Each of these approaches has its strengths and weaknesses, depending upon the nature of the signals and measurements, and the positioning algorithms employed.
  • The Navstar Global Positioning System (GPS) operated by the US Government leverages about two-dozen orbiting satellites in medium-earth orbits as reference points. A user equipped with a GPS receiver can estimate his three-dimensional position (latitude, longitude, and altitude) anywhere at any time within several meters of the true location, as long as the receiver can see enough of the sky to have four or more satellites “in view.” Cellular carriers have used signals originating from and received at cell towers to determine a user's or a mobile device's location. Assisted GPS (AGPS) is another model that combines both GPS and cellular tower techniques to estimate the locations of mobile users who may be indoors and must cope with attenuation of GPS signals on account of sky blockage. In this model, the cellular network attempts to help a GPS receiver improve its signal reception by transmitting information about the satellite positions, their clock offsets, a precise estimate of the current time, and a rough location of the user based on the location of cell towers. No distinction is made in what follows between GPS and AGPS.
  • All positioning systems using satellites as reference points are referred to herein as Satellite-based Positioning System (SPS). While GPS is the only operational SPS at this writing, other systems are under development or in planning. A Russian system called GLONASS and a European system called Galileo may become operational in the next few years. All such systems are referred to herein as SPS. GPS, GLONASS and Galileo are all based on the same basic idea of trilateration, i.e., estimating a position on the basis of measurements of ranges to the satellites whose positions are known. In each case, the satellites transmit the values of certain parameters which allow the receiver to compute the satellite position at a specific instant. The ranges to satellites from a receiver are measured in terms of the transit times of the signals. These range measurements can contain a common bias due to the lack of synchronization between the satellite and receiver (user device) clocks, and are referred to as pseudoranges. The lack of synchronization between the satellite clock and the receiver (user device) clock results in a difference between the receiver clock and the satellite clock, which is referred to as internal SPS receiver clock bias or receiver clock bias, here. In order to estimate a three dimensional position there is a need for four satellites to estimate receiver clock bias along with three dimensional measurements. Additional measurements from each satellite correspond to pseudorange rates in the form of Doppler frequency. References below to raw SPS measurements are intended generally to mean pseudoranges and Doppler frequency measurements. References to SPS data are intended generally to mean data broadcast by the satellites. References to an SPS equation are intended to mean a mathematical equation relating the measurements and data from a satellite to the position and velocity of an SPS receiver.
  • WLAN-based positioning is a technology which uses WLAN access points to determine the location of mobile users. Metro-wide WLAN-based positioning systems have been explored by a several research labs. The most important research efforts in this area have been conducted by the PlaceLab (www.placelab.com, a project sponsored by Microsoft and Intel); the University of California, San Diego ActiveCampus project (ActiveCampus—Sustaining Educational Communities through Mobile Technology, technical report #CS2002-0714); and the MIT campus-wide location system. There is only one commercial metropolitan WLAN-based positioning system in the market at the time of this writing, and it is referred to herein as the WPS (WiFi positioning system) product of Skyhook Wireless, Inc. (www.skyhookwireless.com).
  • FIG. 1 depicts a conventional WLAN-based positioning system based on WiFi signals. The positioning system includes positioning software 103 that resides on a mobile or user device 101. Throughout a particular target geographical area, there are a plurality of fixed wireless access points 102 that transmit information using control/common channel signals. The device 101 monitors these transmissions. Each access point contains a unique hardware identifier known as a MAC address. The client positioning software 103 receives transmissions from the 802.11 access points in its range and calculates the geographic location of the computing device using the characteristics of the radio signals. Those characteristics include the MAC addresses, the unique identifiers of the 802.11 access points, the Time of Arrival (TOA) of the signals, and the signal strength at the client device 101. The client software 103 compares the observed 802.11 access points with those in its reference database 104 of access points. This reference database 104 may or may not reside in the device 101. The reference database 104 contains the calculated geographic locations and power profiles of all access points the system has collected. A power profile may be generated from a collection of measurements of the signal power or signal TOA at various locations. Using these known locations or power profiles, the client software 103 calculates the position of the user device 101 relative to the known positions of the access points 102 and determines the device's 101 absolute geographic coordinates in the form of latitude and longitude or latitude, longitude, and altitude. These readings then can be fed to location-based applications such as friend finders, local search web sites, fleet management systems, and an E911 service.
  • In the discussion herein, raw WLAN measurements from an access point are generally intended to mean received signal strength (RSS) and/or times of arrival (TOAs) and/or time differences of arrival (TDOAs). References to data are generally intended to mean the MAC address, one or more record(s) of it, one or more power profile(s), and other attributes based on previous measurements of that access point. References to a WLAN-PS equation are intended to mean a mathematical equation relating the WLAN-PS measurements and data to the location of the mobile device.
  • A WLAN-based positioning systems can be used indoor or outdoor. The only requirement is presence of WLAN access points in the vicinity of the user. The WLAN-based position systems can be leveraged using existing off-the-shelf WLAN cards without any modification other than to employ logic to estimate position.
  • FIG. 2 illustrates a conventional way of integrating WLAN-PS and SPS, which consists of a WLAN-PS 201 and a SPS 206, and a location combining logic 210.
  • WLAN-PS 201 and SPS 206 are stand-alone systems and each can operate independently of the other system. Thus the result of each system can be calculated independent of the other system. The estimated location along with the expected error estimation of each system can be fed to the location combining logic 210. The expected error estimation is also referred to as HPE (horizontal positioning error) herein. The nominal rate of location update of SPS 206 and WLAN-PS 201 is once a second. The location combining logic 210 combines location estimates calculated in the same second by both systems.
  • WLAN-PS 201 is a conventional system which estimates the location of a mobile device by using WLAN access points. WLAN-PS 201 can include a scanner of WLAN APs 202, a device to select WLAN APs 203, a trilateration module 204, and HPE estimation device 205.
  • WLAN Scanner 202 detects WLAN APs surrounding the mobile device by detecting the received power (RSS, received signal strength) and/or time of arrival (TOA) of the signal. Different methods can be used to detect WLAN APs including active scanning, passive scanning, or combination of passive and active scanning.
  • The select WLAN APs device 203 selects the best set of WLAN APs to estimate location of the mobile device. For example, if ten WLAN APs are detected and one AP is located in Chicago and the others are located in Boston, without any other information, the Boston APs are selected. This is an indication that Chicago AP has been moved to Boston. In the conventional system the best set of WLAN APs is selected based on geographical distribution of WLAN APs in addition to corresponding parameters of WLAN APs, including received signal strength, signal to noise ration, and the probability of being moved.
  • Trilateration module 204 uses WLAN APs and corresponding measurements and characteristics to estimate location of the mobile device. Received signal strength or TOA measurements from WLAN AP are used to estimate distance of the mobile device to the WLAN AP. The aggregation of distance estimates from different WLAN APs with known location is used to calculate location of the mobile device. Trilateration 204 also can use a method which is called nearest neighbor, in which a location with a power profile similar or closest to the power reading of the mobile device is reported as the final location of the mobile device. The power profile of each WLAN AP or entire coverage area can be found in the calibration phase of the system by detailed survey of the coverage area.
  • HPE estimation device 205 is the module which estimates the expected error of the position estimate of the mobile device. The HPE, or Horizontal Positioning Error is calculated based on previously scanned APs and their characteristics and also characteristics of the received signal, as it was explained in co-pending Skyhook Wireless application Ser. No. 11/625,450 entitled “System and Method for Estimating Positioning Error Within a WLAN Based Positioning System,” the entire disclosure of which is hereby incorporated by reference.
  • SPS system 206 consists of a satellite signal receiver and measurement device 207, trilateration device 208, and the SPS HPE estimation module 209.
  • The satellite signal receiver and measurement device 207 receives signals from the satellites in view of the device, decodes the received signal, and measures the satellite parameters from each satellite. The measurements can include pseudorange, carrier frequency, and Doppler frequency.
  • The trilateration device 208 uses measurements from at least four satellites and location of the satellites in view to estimate location of the user device, velocity, and direction of travel of the mobile device.
  • HPE estimation device 209 estimates the expected error of the estimated location. The HPE estimation device 209 is conventional and calculates expected error based on geometry of the satellites and signal quality of the received signal from satellites, for example, DOP (dilution of precision), and C/N (carrier to noise ratio).
  • Location combining logic 210 receives location and HPE estimates calculated for almost the same second from WLAN-PS 201 and SPS 206. In other words, measurements and estimations which are made at the same time are compared and combined. Practically, measurements and estimations within one second can be considered the same time. The location combining logic 210 of the user device reports one estimated location by selecting one of them or linearly combining them. For example, location combining logic might select one of the estimated locations provided by WLAN-PS 201 or SPS 206 based on reported expected error or HPE, or it might report weighted average of estimated locations by both systems according to the HPE.
  • SUMMARY
  • This disclosure describes methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system. In some embodiments, the method of determining an expected error in a location determination of a WLAN and satellite enabled device can include determining a WLAN location estimate and an expected error estimate for the WLAN location estimate, obtaining measurements from at least two satellites, and determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.
  • In some embodiments, consistent measurements between the WLAN location estimate and the satellite positioning system measurements can result in a lower expected error in the location determination.
  • In some embodiments, inconsistent measurements between the WLAN location estimate and the satellite positioning system measurements can result in a higher expected error in the location determination.
  • In some embodiments, consistency of the measurements can include the distance between the WLAN positioning system location estimation and a region of possible solutions provided by the satellite positioning system measurements.
  • In some embodiments, the consistency of the internal SPS receiver clock for the WLAN based position estimate can be used as an indication of consistency between the WLAN based position estimate and the satellite measurements.
  • In some embodiments, the method can include determining a WLAN based location estimate and an expected error estimate for the WLAN location estimate, determining a satellite based location estimate and an expected error estimate for the satellite based location estimate, determining the expected error of the location determination by evaluating the consistency of the satellite positioning system location estimate to the WLAN positioning system location estimation.
  • In some embodiments, the position estimate with the lower expected error can be selected as the location of the WLAN and satellite enabled device.
  • In some embodiments, the method can include determining the expected error of the location determination by comparing the WLAN location estimate and the satellite positioning system location estimate.
  • In some embodiments, consistent measurements between the WLAN location estimate and the satellite positioning system location estimate can result in a lower expected error in the location determination.
  • In some embodiments, inconsistent measurements between the WLAN location estimate and the satellite positioning system location estimate can result in a higher expected error in the location determination.
  • In some embodiments, the consistency of the estimates can include the distance between the satellite positioning system location estimate and the WLAN positioning system location estimation.
  • In some embodiments, the method can include the internal SPS receiver clock for the WLAN based position estimate is used as an indication of consistency between the WLAN based position estimate and the satellite positioning system location.
  • Some embodiments relate to a system for increasing the accuracy of a WLAN based position estimate using satellite positioning information. The system can include a positioning module including a WLAN module for receiving information from one or more WLAN access points to calculate a WLAN location estimate, a satellite positioning module for obtaining satellite information from at least two different satellites, and logic located in the positioning module for determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.
  • Some embodiments relate to a system for increasing the accuracy of a WLAN based position estimate using satellite positioning information. The system can include a positioning module including a WLAN module for receiving information from one or more WLAN access points and to calculate a WLAN position estimate, a satellite positioning module for obtaining satellite information from at least four different satellites to calculate a satellite position estimate, and logic located in the positioning module for determining the expected error of the location determination by evaluating the consistency of the satellite positioning system location estimate to the WLAN positioning system location estimation.
  • BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
  • For a more complete understanding of various embodiments of the present invention, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:
  • FIG. 1 illustrates a high-level architecture of a WLAN positing system;
  • FIG. 2 illustrates a system for a conventional way of integrating WLAN-PS and SPS;
  • FIG. 3 illustrates a system for providing a WLAN-PS and SPS integrated solution according to some embodiments of the disclosed subject matter;
  • FIG. 4 illustrates an example of selecting a solution between possible WLAN-PS solutions using raw SPS measurements from two satellites according to some embodiments of the disclosed subject matter;
  • FIG. 5 illustrates a system for integrating WLAN-PS and SPS in which raw SPS measurements are provided to WLAN-PS to select the best solution according to some embodiments of the disclosed subject matter;
  • FIG. 6 illustrates an example of selecting a solution between possible WLAN-PS solutions based on SPS possible solutions according to some embodiments of the disclosed subject matter;
  • FIG. 7 illustrates an example of selecting the best set of WLAN APs based on raw SPS measurements according to some embodiments of the disclosed subject matter;
  • FIG. 8 illustrates a system for integrating WLAN-PS and SPS and using raw SPS measurements from two or more satellites to select a set of WLAN APs in WLAN-PS according to some embodiments of the disclosed subject matter;
  • FIG. 9 illustrates a system for examining the location estimate and uncertainty provided by WLAN-PS against SPS in order to find the best estimate of the location of a mobile device according to some embodiments of the disclosed subject matter;
  • FIG. 10 illustrates a system for examining the location estimate and uncertainty provided by WLAN-PS against SPS in order to find the best estimate of the location of a mobile device by using the grid method according to some embodiments of the disclosed subject matter;
  • FIG. 11 illustrates a system for integrating WLAN-PS and SPS, in which raw SPS measurements are used to refine WLAN-PS location estimate according to some embodiments of the disclosed subject matter;
  • FIG. 12 illustrates a system for integrating WLAN-PS and SPS, in which as WLAN-PS location estimate is provided as initial location estimate according to some embodiments of the disclosed subject matter;
  • FIG. 13 illustrates an example for increasing accuracy of the estimation of expected error by using SPS and WLAN-PS information according to some embodiments of the disclosed subject matter;
  • FIG. 14 illustrates a system for increasing accuracy of the estimation of expected error by using SPS and WLAN-PS information according to some embodiments of the disclosed subject matter;
  • FIG. 15 illustrates a system for stationary user detection based on two or more satellites according to some embodiments of the disclosed subject matter.
  • DETAILED DESCRIPTION
  • Embodiments of the disclosed subject matter provide a method of integrating a WLAN-based positioning system (WLAN-PS) and a satellite-based positioning system (SPS) to create a hybrid positioning system. An integrated or hybrid system refers to a system which combines the measurements from one or more systems to improve the accuracy of the positioning and velocity and bearing estimates and the accuracy of expected error estimate, and to reduce consumed power as compared to each individual system working independently. The method of integrating a WLAN-PS and SPS to create a hybrid positioning system can add raw SPS measurements as another input to WLAN-PS and WLAN-PS final estimations as another input to SPS. Raw SPS measurements from two or more satellites can assist the WLAN-PS to increase the accuracy of position estimate, HPE, and stationary user detection. WLAN-PS initial position estimate and other estimations also can help SPS to reduce time to first fix (TTFF) and power consumption. A hybrid positioning system also can reduce power consumption compared to WLAN-PS and SPS working independently by deactivating WLAN-PS or SPS when they are not adding value in terms of increasing accuracy or other estimations.
  • FIG. 3 illustrates a block diagram of the hybrid system of a WLAN-PS 301 and a SPS 306.
  • SPS 306 is an off-the-shelf, conventional satellite positioning device which consists of the same devices as SPS 206 in FIG. 2, with addition of an output 311 and an input 312 from the WLAN-PS (discussed in more detail herein). Satellite receiver and measurement device 207 is part of every conventional SPS receiver 306, and raw SPS measurements are an essential part of the SPS measurement. However, here the raw SPS measurements are used outside the SPS 306, as is shown by output 311. Not all the commercial SPS receivers expose the raw SPS measurements to devices outside SPS 306. For example, Star III GPS manufactured by SiRF Technology, Inc. (San Jose, Calif.) provides raw SPS measurements as part of its standard interface. However there are some other GPS receivers that do not provide such measurements. For the SPS receivers that do not expose raw SPS measurements as part of their standard interface, the SPS receiver 306 is modified to permit access to the raw SPS measurements.
  • The WLAN-PS 301 functions in a similar manner as the WLAN-PS 201 shown in FIG. 2 except that it is configured to receive raw SPS measurements 311. The integration of the raw SPS measurement with WLAN-PS 301 changes the design of WLAN APs selection device 303, trilateration device 304, and HPE estimation device 305. The WLAN-PS 301 can take advantage of the raw SPS measurements when at least two satellites are acquired, even without any fix or solution from the SPS 306.
  • This design change of WLAN-PS 301 after receiving raw SPS measurements is discussed in more detail herein.
  • Under one embodiment, the disclosed method integrates a WLAN-based positioning system (WLAN-PS) and a satellite-based positioning system (SPS) in which the WLAN-PS provides a set of possible locations of a mobile device, and among the possible locations, the one which fits the SPS measurements the best is selected as the final position estimate.
  • This embodiment also can provide a method to integrate WLAN-based positioning system (WLAN-PS) and satellite-based positioning system (SPS) in which the WLAN-PS provides a set of possible locations for the mobile device, and the possible locations are weighted according to their distance to a plurality of possible SPS device location solutions. In other words, weights are assigned to WLAN-PS possible solutions according how well they correspond to the satellite measurements. After assigning a weight to each possible location, various algorithms can be used to combine or select WLAN-PS possible locations. For example, the final reported location can be weighted by an average of all possible locations, low weight locations can be removed from the weighted average, or only the highest weighted location can be reported. Selection can be a special case of weighting, in which the respective weights are zero and one.
  • For example, because of the high density of WLAN APs in some areas, WLAN-PS can detect tens of WLAN APs in a given location. The detected WLAN APs may form more than one cluster. A cluster is defined as a set of APs in the coverage area of each other. If the coverage of a WLAN AP is not known, a nominal coverage can be considered. Nominal coverage or typical coverage of a WLAN AP is found statistically by measuring coverage for thousands of WLAN APs, and it is reported numbers between 100 m and 250 m at the time of writing this document. For example, if a mobile device detects fifteen WLAN APs, in which ten of them are located in a high-rise building and the other five are located in an office building far from the high-rise building (for example, 500 meters away from the high rise building), the detected WLAN APs can be considered as two clusters with a size of ten and five, respectively. Conventional positioning algorithms would select the cluster with a higher number of APs: the cluster of ten APs. Under the conventional approach, the location would be somewhere in the high-rise building. However, if raw SPS measurements from two or more satellites are considered with the cluster information, even with no location estimate from SPS, the raw SPS measurements can be used to select the appropriate cluster of WLAN APs from the plurality of clusters. In this example, the cluster of five WLAN APs might be selected as the closest cluster to the location of the mobile device, because it also satisfies the SPS equations. SPS measurements also can be used to assign a weight to the clusters of five and ten APs according to their estimated distance from possible SPS solutions. After assigning a weight to clusters, logic can be used to combine the estimation results of clusters and report only one location. For example, the weighted average of estimation results of clusters, estimations of the cluster with maximum weight, or average of estimation of clusters with higher weights can be reported as final estimation results.
  • The first step is detecting WLAN access points, which will be used as reference points to locate the user device. WLAN access points are randomly distributed, and they also might move over time. Therefore, the WLAN positioning system applies a clustering algorithm to identify all the clusters of WLAN access points that are detected by the end user.
  • A cluster of WLAN access points is a set of WLAN access points which are in the coverage area of each other. WLAN access points which are farther than a normal coverage of an access point from the cluster are considered as a new cluster.
  • For example, a user detects four access points and three of them are located in Boston and one of them in Seattle. Therefore, they form two clusters: one in Boston with three WLAN access points and one in Seattle with one WLAN access point. Each cluster of WLAN access point can result to a separate location in a WLAN positioning system. If the mobile device also acquires signals from two or more satellites, the satellite measurements can be used to select the cluster of WLAN access points or reject clusters of WLAN access points. Two or more satellite measurements provide a set of solutions in a form of a region (volume, surface or a curve). The proximity of possible WPS solutions to SPS possible solutions can be criteria to weight, select, or reject WPS solutions. In other words, the closer the WLAN-PS solution to the SPS solutions, the higher the quality of the WLAN-PS solution.
  • For example, FIG. 4 shows a WLAN-PS 401, which consists of five WLAN access points 404. The WLAN access points form two clusters in this example, a first cluster 402 and a second cluster 403. Each cluster can be used to estimate the location of the user device. If the user device acquires a signal from at least two satellites 405, the possible solutions of the two or more satellites 406 can be used to select or eliminate some clusters. In this example, possible solution of the two or more satellites is shown as a band 406. Cluster 402 is closer to the possible satellite solutions band 406 than cluster 403. Therefore, cluster 402 can be selected and cluster 403 can be rejected.
  • FIG. 5 illustrates block diagram of integrated solution of SPS and WLAN-PS. SPS 506 can be a standard, off-the-shelf device, but it has to be able to provide raw SPS measurements as discussed in FIG. 3. The raw SPS measurements 311 are directed to WLAN APs 503 and trilateration device 504.
  • The WLAN APs selection devices 503 receives the data from WLAN scanner 202 as an input. The WLAN APs selection device 503 clusters WLAN APs based on the distance between the access points. The WLAN APs selection device 503 not only identifies clusters, but also selects a different set of WLAN APs for each cluster. Each different cluster may result in a different location estimate. All of the different sets of clusters can be used in the trilateration device 504 and may result in a different location estimate. The location estimates based on clusters can be weighted according to the cluster distance from the SPS possible solutions or can be selected according to their cluster distance from SPS possible solutions. A cluster can be assigned a high weight if it is considered close (at a small distance) from the satellite distance solution. For example, if the cluster is located on the order of 10 meters away from the satellite distance solution. A cluster can be assigned a low weight if it is considered far (at a large distance) from the satellite distance solution, for example, if it is located on the order of 100 or 1,000 meters away from the satellite distance solution.
  • The SPS solutions can be found as follows. In each satellite measurement, there are generally four unknowns coordinates of location of the mobile device, (x,y,z) and internal clock bias of SPS receiver. The raw SPS measurements from two or more satellites can be used to eliminate the internal clock bias of the SPS receiver from the equations. In this case, the result is going to be a function of coordinates of the location of the user device, (x,y,z), which can be written as a general form as follows:

  • F(x,y,z)=0.
  • This function can represent an area, a surface, or a curve based on number of satellites. Therefore, raw SPS measurements from two or more satellites can result in a set of possible solutions, even without having a final location estimate.
  • The distance between the different solutions of WLAN-PS and possible solutions of SPS can be used as criteria to weigh each WLAN-PS solution. After assigning a weight to each WLAN-PS possible solution, logic can be used to combine the solution or select the solution from the possible solutions.
  • Further, the consistency between the SPS measurements and the locations provided by the WLAN-PS can be used as an indication of distance between the locations provided by the WLAN-PS and location of the mobile device. The location of the user device can be calculated by (1) using the possible WLAN-PS locations as rough estimates of the location of the user device (i.e., using each possible WLAN-PS location as the x,y,z) and (2) calculating the final unknown, internal satellite receiver clock bias, for each WLAN-PS location estimate using the measurements from each satellite. The consistency between the calculated internal satellite receiver clock biases (calculated for each satellite in view) for each WLAN location estimate can be used as an indicator of distance between WLAN-PS's location estimate and the mobile device actual location. Good WLAN-PS estimates will have consistent receiver clock bias estimates, i.e., when that WLAN-PS estimated location is used as the x,y,z location, for each satellite, the receiver clock bias will be substantially the same, for example, within about 10% of each other. However, if the WLAN-PS location is a poor estimate of the location of the user device, the WLAN-PS location will produce varied satellite receiver clock bias estimates for each satellite, for example, the receiver clock biases will vary by at more than 10%.
  • If clock bias which is found for each satellite measurement is denoted by Ci, the consistency of Ci can be used as a measure of distance between a given position (in this case, locations determined by the WLAN-PS) and the locations that satisfy the satellite equations. The consistency of Ci can be measured with different mathematical approaches, like standard deviation of Ci, or mean square error of Ci estimation as follows:
  • C _ = i = 1 N C i N M S E = i = 1 N ( C i - C _ ) 2 N
  • The value of MSE can be used as an indicator of the consistency of the Ci samples. Therefore, all possible locations of WLAN-PS can be examined with SPS raw measurements, and the consistency of Ci can be used as an indicator of the solution's distance to the actual mobile device location. This distance can be used with other WLAN AP parameters to weight or select or deselect (remove) an AP in the process of calculating the mobile device location.
  • FIG. 6 shows SPS solution in form of a region 606 and a WLAN positioning system 601, in which WLAN access points 604 form a first cluster 602 and a second cluster 603. The mobile device acquisition of two or more satellites 605 also can result in a set of possible satellite device solutions 606. The consistency between the SPS solutions 606 and WLAN-PS solutions 602 is used to select the best solution, which is the 602 solution of WLAN-PS in this example. The consistency between the SPS and WLAN-PS means both of them report the same location as part of their solutions or that the final estimated position is one of the solutions of both systems. Further, a cluster of APs can be weighted according to their distance to possible solutions of SPS.
  • Another embodiment of the disclosed subject matter provides a method to weigh WLAN access points by using raw SPS measurements. Selecting the best set of WLAN access points to estimate end user's location by using raw SPS measurements can be a specific case of assigning a weight to WLAN APs. In addition to other criteria used to weight or select the best set of WLAN access points to estimate the mobile device location, raw SPS measurements can be used or combined with the other criteria. Other criteria and weights are weight based on received signal strength or weight based on round trip time of received signal. The WLAN-PS uses WLAN APs and their characteristics to estimate the location of a mobile device.
  • The characteristics of a WLAN AP might include, but are not limited to, received signal strength (RSS), location or estimation of location, signal to noise ratio, and time of arrival (TOA). Raw SPS measurements from two or more satellites are used to calculate an indication of distance between location (or estimated location) of WLAN APs and actual location of the mobile device. This indication of distance can be used to select the best set of WLAN APs to estimate location of the mobile device, or the indicator of distance can be used to weight WLAN APs according to their distance from the device location. The raw SPS measurements from at least two satellites can be used in this process, with or without having a location estimate from SPS. The distance is considered far if the distance is more than an order of magnitude larger than the coverage area of the WLAN AP. A distance is considered close or not far is the distance is within an order of magnitude of the coverage area of the WLAN AP. WLAN APs that are considered far can be eliminated from the positioning calculation.
  • FIG. 7 shows an example of an integrated solution of WLAN-PS and SPS, in which the mobile device detects five WLAN access points 702 and has acquired a signal and raw measurements from two satellites 704. In this example, the WLAN access points are randomly spread around the mobile device, and distance between WLAN access points 702 and possible solutions of two satellites 703 can be used as an indication of distance between WLAN access point and actual location of the mobile device. A region of possible SPS solutions 703 is calculated using measurements from two satellites. The distance between the WLAN access point 702 and SPS possible solution 703 is used as an indicator of distance between WLAN access point and actual location of the mobile device. In this example, all the WLAN access points 702-1 are very close to SPS possible solutions 703, but one WLAN access point 702-2 is not. Therefore, the longer distance between WLAN access point 702-2 and possible SPS solutions 703 is an indicator of a larger distance between WLAN access point 702-2 and the location of the mobile device compared to other detected WLAN access points 702-1. Thus, WLAN access point 702-2 can be weighted according to its distance to SPS possible solutions, or it can be removed from the set of APs to calculate the mobile device location.
  • FIG. 8 illustrates WLAN-PS 801 and SPS 806 integrated solution, in which all the modules are the same as FIG. 2, except for selecting WLAN APs 803. Selecting WLAN APs 803 also receives raw SPS measurements 311 as an input. These raw measurements are used to estimate the distance between the location (or estimated location) of WLAN APs and the location of the mobile device.
  • As discussed in the previous embodiment, in this embodiment there is a need to calculate an indication of the distance between WLAN APs location (or estimated location) and actual location of the mobile device using SPS measurements from two or more satellites. The consistency between the raw SPS measurements and the WLAN APs can be used as an indication of distance between the location of WLAN APs and the location of the mobile device. The consistency can be calculated by (1) using the WLAN AP's location as an estimation of the location of the mobile device and (2) calculating the receiver clock bias for each WLAN AP location based on the measurements from each satellite. The consistency between calculated receiver clock biases can be used as an indicator of distance between WLAN APs location and the mobile device's actual location.
  • In other words, after applying the location of a WLAN AP as an initial position in SPS equations using pseudorange measurements, the only remaining unknown is the receiver clock bias, which is the same for all SPS raw measurements. If clock bias which is found for each satellite measurement is denoted by Ci, the consistency of Ci is used as a measure of distance between the given position (in this case, location of WLAN AP) and the location that satisfies the satellite equations. Consistency of Ci can be measured with different mathematical approaches, like standard deviation of Ci, or mean square error of Ci estimation as follows:
  • C _ = i = 1 N C i N M S E = i = 1 N ( C i - C _ ) 2 N
  • The value of MSE can be used as an indicator of the consistency of the Ci samples. Therefore, the location of all the detected WLAN APs can be examined with SPS raw measurements, and the consistency of Ci can be used as an indicator of their distance to the mobile device location. This indicator can be used with other AP parameters to weight, select, or remove an AP in the process of calculating the mobile device location.
  • Under another embodiment of the disclosed subject matter, a system and method is provided in which the WLAN-PS provides a region in which a possible location solution resides, and within the provided region, the final location estimate of the mobile device is selected based on SPS measurements from two or more satellites.
  • FIG. 9 shows an integrated WLAN-PS and SPS, in which WLAN-PS 901 provides an estimate of the location of the mobile device with some uncertainty 903. The uncertainty 903 can be the expected error of WLAN-PS. The mobile device also acquires signal from two or more satellites 902. Using all the points within the uncertainty area 903 reported by WLAN-PS, the location 904 which fits the satellite measurements the best is selected as the best estimate of location of the mobile device.
  • The best point which fits satellite solutions within that region can be found by dividing the uncertainty area 903 to small grids and evaluating each grid point as is shown in FIG. 10. The distance between grid lines can be based on the required accuracy of location estimation and the quality of the SPS measurements. The higher the accuracy requirement and the quality of the SPS measurements, the smaller the distance between the grid lines can be and the more accurate the location estimate. For example, the grid lines can be between about 5 meters and about 100 meters apart, preferably at about 10 meters apart.
  • In this embodiment, the number of SPS satellites 902 can be two or more. This system or method can be used in cases where the SPS cannot determine the location of the mobile device by itself but where the WLAN-PS possible solution 903 can be examined with the SPS information to select as the best location 904 the one that is most consistent with the SPS pseudorange equations.
  • FIG. 11 shows an integrated solution of WLAN-PS 1101 and SPS 1106, in which final location estimate provided by WLAN-PS is refined by using SPS measurements 311 from two or more satellites. A new module, refining module 1111, is added to conventional WLAN-PS, which receives WLAN-PS trilateration results, the corresponding uncertainty of those measurements, and SPS measurements from two or more satellites. Using this information, the refining module 1111 reports the location estimate of the mobile device.
  • For example, if the WLAN-PS provides a sphere of possible location solutions to refining module 1111. The size of the sphere corresponds to the uncertainty of the location estimate of WLAN-PS (expected error), which can be calculated for each position estimate in some embodiments, or the nominal value of uncertainty of WLAN-PS can be used. For example, median error of Skyhook Wireless WLAN-PS is about 30 m, which can be used as nominal value of WLAN-PS error. In the next step, SPS measurements from two or more satellites can be used to find a point within the specified region by WLAN-PS, which satisfies the SPS measurements the best. The satellite equation for each satellite is written as follows:

  • Fi(x,y,z,b)=0
  • In which (x, y, z) is location of the mobile device, and b is denoted for the internal clock bias of SPS receiver. Any point within the specified region by WLAN-PS provides an estimate for the location of the mobile device, (x, y, z), and internal clock bias is calculated for each acquired satellite. Because all the measurements are done at almost the same time by the same SPS receiver, the internal clock bias of SPS receiver should be almost the same for all the SPS measurements. Therefore, as discussed previously, the consistency between receiver clock biases of SPS receiver calculated from different acquired satellites can show the distance between location estimate (x,y,z) and actual location of the mobile device. The consistency of the calculated internal clock of SPS receiver can be measured by calculating the standard deviation of the receiver clock bias measurements.
  • In the case where the specified region by WLAN-PS is divided into a grid, the SPS equations are examined at each grid point. The grid point which provides the most consistent receiver clock bias for all the acquired satellites is the best location estimate of the mobile device.
  • Another embodiment of the invention provides a method to reduce acquisition time of SPS by providing a position estimate of WLAN-PS as an initial position to SPS. Providing an initial position by WLAN-PS can reduce the acquisition period of the SPS and therefore reduces time to first fix of SPS. Satellite positioning systems already provide a method to receive an initial position, and how they use the provided initial position inside SPS is generally known. The present system uses a WLAN-PS location estimate as a source of initial position for the satellite positioning system. Because the location of SPS satellites are known at any time, knowledge of a rough location of the mobile device can help the SPS to reduce the set of satellites it searches for to the set of satellites actually visible to the device, instead of all of the satellites, thereby reducing searching time.
  • FIG. 12 illustrates a WLAN-PS 201 and SPS 1203, in which WLAN-PS provides an initial position 1211 to the SPS system. Thus, the estimated location of the mobile device 1211 by the WLAN-PS 201 can be provided as initial position to SPS 1202. Knowing the initial position of the mobile device can assist SPS 1202 to select the best set of the satellites to search and reduce time to fix a location of the device.
  • The WLAN-PS and the SPS can work independently and provide estimates of attributes of a mobile device, including location estimation, expected error in the location estimation, velocity, and bearing estimation. However, because WLAN-PS has a much shorter time to first fix (TTFF) than SPS, the estimated location by WLAN-PS can be provided to SPS as initial position of the mobile device, reducing the time required to find location.
  • The receipt of an initial position is a standard practice in SPS, and most of the SPS receivers provide a method to receive the initial position. Here the WLAN-PS is used as the source of providing the initial position to SPS.
  • Another embodiment of the invention provides a method to increase the accuracy of the expected error of location estimate of the integrated location solution of SPS and WLAN-PS and compare the error to the error location result for each individual system. The expected error estimation provides an uncertainty area around the estimated location. If estimated location of WLAN-PS and SPS are within the uncertainty area of each other, the uncertainty area is reduced based on distance between estimated locations from both systems. If estimated locations of WLAN-PS and SPS are not within the uncertainty area of each other, the uncertainty area is increased based on distance between estimated locations from both systems. If only one of the estimated locations of WLAN-PS and SPS falls inside the uncertainty area of the other system, the uncertainty area can be reduced or increased based on quality of estimated error from each system. The estimated error of location estimate normally reports the 95% confidence interval, but it can report any other confidence interval as well.
  • Another embodiment of the invention provides a method to increase the accuracy of the expected error of a location estimate of the integrated location solution of SPS and WLAN-PS. The WLAN-PS provides a location estimate and the SPS acquires at least two satellites. The expected error estimation provides an uncertainty area around the estimated WLAN-PS location. The consistency between the estimated location of WLAN-PS and raw SPS measurements is used as criteria to reduce or increase the expected error estimate. If estimated location estimate of WLAN-PS and raw SPS measurements are consistent, the uncertainty area is reduced based on distance between WLAN-PS estimated location from SPS possible solutions. If the estimated location of WLAN-PS and raw SPS measurements are not consistent, the uncertainty area is increased based on distance between WLAN-PS estimated locations from SPS possible solutions.
  • FIG. 13 illustrates WLAN-PS location estimation 1301 and WLAN-PS expected error of estimation 1303 and also SPS location estimation 1302 and SPS expected error of estimation 1304. The reported uncertainty by each system is the expected error of position estimate.
  • In such a system, the SPS and WLAN-PS each provides a location estimate and also an estimate of the expected error in that location estimation. The expected errors of the location estimate provided by both systems are combined in order to provide a better estimate of the error of the location estimation. For example, if each system provides an area around the reported location as an uncertainty of the estimated location (1303 and 1304), the integrated system considers the overlap of the uncertainty areas 1305 and also the distance between estimated locations 1306 to estimate the uncertainty of the final location estimate. The greater the distance between the estimated locations by SPS and WLAN-PS is, the higher the expected error of location estimation. In another implementation, the system can select the location estimate with the lowest uncertainty as the final location estimate.
  • FIG. 14 illustrates a block diagram of integrated WLAN-PS and SPS system, in which the expected error of each system is calculated using conventional method and the results are provided to integrated error estimation system device 1411. The integrated error estimation 1411 calculates the final expected error by considering the consistency between the reported locations by WLAN-PS and SPS. The consistency can also be determined by comparing the receiver clock bias, as discussed previously.
  • In some embodiments, the SPS can detect that the mobile device is stationary. In general, it takes measurements from four SPS satellites to estimate the velocity or speed of a mobile device. The present method and system can determine if the mobile device is stationary by using the measurements from as few as two satellites by examining the consistency of the Doppler frequency measurements from the two or more satellites. If the device is stationary, the Doppler measurements from SPS must be fully accounted for by satellite motion relative to initial position of the device and the frequency offset of the receiver clock. The receiver clock offset can be estimated, given the Doppler measurements from two or more satellites. The hypothesis that the user is stationary is based on the size of the residuals after the estimated receiver frequency bias is substituted in the SPS Doppler equations.
  • By knowing that a mobile device is stationary, the hybrid system can cause the WLAN-PS to respond differently than when the device is in motion. For example, WLAN-PS can save power by updating the location less often, for example, once a minute. In addition, the WLAN-PS can consider all of the detected WLAN access points over the time interval that the mobile device is stationary and use the collective information to estimate an improved location of the mobile device. This is because the WLAN-PS can obtain a better estimate of the received signal strength from an access point and better mitigate power fluctuation due to multi-path when user is stationary. Multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths and causes power to fluctuate, and it is a known phenomena by experts in the radio propagation field.
  • FIG. 15 illustrates stationary user detection based on two or more satellites. If the mobile device 1503 detects two or more satellites, 1501, 1502 one can determine that the mobile device is stationary or moving from Doppler measurement of the received signal from satellites.
  • The first step is finding a rough location of the mobile device 1503, which can be calculated by WLAN-PS. This rough estimate of location of the mobile device can be provided by other positioning technologies as well. The rough estimation of the location of the mobile device can have an error of up to about a couple of kilometers although accuracy of rough estimation of location by WLAN-PS is maximum couple of hundred meters.
  • The mobile device can acquire a signal from at least two satellites, which are shown with satellites 1501 and 1502 in FIG. 15. The mobile device also knows the velocity of the satellites at the exact time of signal acquisition. In other words, if the mobile device 1503 acquires a signal from satellites 1501 and 1502 at time t, the velocity of the satellites at time t also is known by the mobile device. The mobile device 1503 can determine the velocity of the acquired satellites 1501 and 1502 by decoding the messages received from the satellites, as all satellite broadcasts its velocity at any moment of time. The mobile device can also receive satellite velocity from other sources, for example, a cellular network.
  • Velocity is a vector with magnitude and direction, and it was shown with velocity of V1 and V2 for satellites 1501 and 1502, respectively. Doppler frequency due to satellite movement is calculated based on velocity. The simplified equation to find Doppler frequency for each satellite is as follows:
  • f d 1 = v 1 λ f d 2 = v 2 λ ( 1 )
  • The λ is wavelength of SPS radio wave and it is known for any SPS system, and fd is the Doppler frequency.
  • The mobile device measures the frequency of the received signal from each satellite. Since the transmit frequency of each satellite is known, the mobile device can measure the difference between the frequency of the received signal and the transmitted signal. The difference between received and transmitted frequency are denoted by fm1 and fm2 for satellites 1501 and 1502, respectively.
  • If the mobile device frequency offset of the internal clock is fo and the velocity of the mobile device 1503 is vm, the measured frequency from each satellite is calculated as follows:
  • f d 1 cos ( α 1 ) + f o + v m λ cos ( β 1 ) = f m 1 f d 2 cos ( α 2 ) + f o + v m λ cos ( β 2 ) = f m 2 ( 2 )
  • The angles α1 and α2 are between the velocity vector of the satellites and the lines connecting the mobile device to the satellites for satellite 1501 and 1502, respectively. The mobile device can calculate the angles based on the devices location, the location of the satellites, and the velocity vector of the satellites. If the mobile device is stationary, the above equations are rewritten as follows:

  • f d1 cos(α1)+f o =f m1

  • f d2 cos(α2)+f o =f m2   (3)
  • The only unknown for the mobile device in these equations is f0, and it can be found from each satellite equation independently. If the mobile device is stationary, the values of f0 from all the acquired satellites are going to be the same. In other words, if the values of f0 from equations for all the acquired satellites are not the same, the mobile device is not stationary.
  • Another embodiment of the disclosed subject matter relates to a method for providing characteristics of the environment of a mobile device by using WLAN-PS. WLAN APs are stationary radio transceivers with relatively small coverage, which are surveyed for positioning purposes. During the survey process, one of the characteristics associated with the WLAN APs can be characteristics of the environment. Then the detected WLAN access points by a mobile device are used collectively to determine the environment in which a mobile device is operating. The environmental characteristics can be considered as attributes of WLAN access points, for example, density of buildings near the AP height of buildings near AP, and whether the AP is in an urban canyon, urban, or suburban location. The data on the environmental characteristics of the access points can reside in the reference database of the access points and can be obtained there by the user device. The granularity of the area, which is characterized by WLAN access points, can be different, and it can be as small as a building or as big as a neighborhood. Environmental information can be used by SPS, WLAN-PS, and also an integrated solution of both systems to adjust the systems approach to position acquisition and/or for power management. For example, knowledge of the fact that a mobile device is in an urban canyon environment might cause the hybrid system to rely on WLAN-PS alone, while in a suburban environment, SPS might be considered as the primary source of estimation of position and other attributes of the mobile device.
  • Another embodiment of the disclosed subject matter and system provides a method to maintain the stability of the internal clock of a SPS receiver by using the WLAN APs. This can be accomplished by measuring known time intervals of the signal transmitted by a WLAN device equipped with a stable clock. Maintaining the internal clock stability of a SPS receiver is important for position determination. For example, it can help in acquiring satellite signals faster, being able to operate at lower power, and also providing a fix (location estimation) with fewer satellites. A WLAN standard defines constant time intervals, including, but not limited to, some packet headers, some fields in some packets, as in WLAN 802.11 standard DIFS (DCF Inter Frame Space), SIFS (Short Inter Frame Space), or slot duration, and a mobile device can use these known time intervals to measure its internal clock bias over time and maintain its stability.
  • There might be WLAN access points with different clock stability. In this case, data identifying the access points which are equipped with a stable clock can be considered as part of characteristics of the WLAN AP and/or the characteristics can reside in the access point data base and can be obtained from there.
  • In addition to providing initial position and clock information, the WLAN positioning system can provide clock updates to the WLAN-enabled SPS receiver. Every SPS receiver is equipped with an internal oscillator in order to maintain its indication of GPS clock information. However, because these oscillators are imperfect at maintaining an exact measurement of time, the clocks internal to the SPS receivers drift. This clock drift can cause position estimation errors. By the WLAN-PS providing the correct GPS clock information to the SPS system, the WLAN positioning system facilitates avoiding such position estimation errors. Furthermore, because the SPS receivers are able to maintain a highly accurate measure of the GPS clock information, they can operate at relatively lower signal to noise ratio (SNR) values in the position estimation calculations. Maintaining SPS timing by SPS receiver reduces time uncertainty of received signals from satellites. Therefore, it is easier to extract signal from noise, and SPS receiver can detect weaker signal and operate in harsher locations in terms of SPS signal. Thus aspects of the method allow SPS receivers to operate in areas having less that ideal SPS signal conditions.
  • Another embodiment of the present disclosure relates to using WLAN municipal networks to increase the accuracy of SPS receiver estimations by providing initial timing and location information to the SPS receiver. WLAN municipal networks are city wide WLAN networks which are installed in city by city officials or under their supervision to provide wireless connection using WLAN technology. Aspects of this method and system of improving SPS receiver position estimation accuracy by using WLAN municipal network data consists of the following items:
  • In order to assist the SPS position estimation by providing GPS clock information, the municipal WLAN access points should be synchronized with the GPS clock. WLAN access points of a municipal network can be synchronized with the GPS clock by using one of the following methods as examples: (1) use of SPS enabled WLAN APs where each WLAN AP in a municipal network can be equipped with a device which extracts the GPS clock information from GPS radio signals, (2) use of centralized clock distribution entity synchronized where the GPS clock information can be extracted at one place and then distributed to all the WLAN APs in the municipal network, and (3) use of a high quality oscillator in WLAN AP. An oscillator is used to measure time and maintain synchronization with the GPS clock. As long as the quality of the WLAN AP oscillator is higher than the SPS receiver oscillator, the timing provided by the WLAN AP is going to be higher than the SPS receiver. Therefore, the SPS receiver can use WLAN AP to maintain its timing better than using its internal clock. The single module that extracts the GPS clock information (herein “Clock Distribution Entity”) is the only unit and only place which extracts the GPS clock information and then provides timing to all the WLAN access points in the network.
  • Further, when the WLAN receiver is integrated into the SPS receiver the SPS receiver can use the WLAN receiver to extract timing information from the signals received from WLAN access points of WLAN municipal networks. While the idea of providing initial timing to SPS receiver has been explained for WLAN municipal networks, it can be applied to any WLAN network which is synchronized to a GPS clock.
  • Upon review of the description and embodiments of the present invention, those skilled in the art will understand that modifications and equivalent substitutions may be performed in carrying out the invention without department from the essence of the invention. Thus the invention is not meant to be limiting by the embodiments described explicitly above and is limited only by the claims which follow. Further, the features of the disclosed embodiments can be combined, rearranged, etc., within the scope of the invention to produce additional embodiments.

Claims (23)

1. A method of determining an expected error in a location determination of a WLAN and satellite enabled device, the method comprising:
determining a WLAN location estimate and an expected error estimate for the WLAN location estimate;
obtaining measurements from at least two satellites; and
determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.
2. The method of claim 1, wherein consistent measurements between the WLAN location estimate and the satellite positioning system measurements result in a lower expected error in the location determination of the WLAN and satellite enabled device.
3. The method of claim 1, wherein inconsistent measurements between the WLAN location estimate and the satellite positioning system measurements result in a higher expected error in the location determination of the WLAN and satellite enabled device.
4. The method of claim 1, wherein consistency of the measurements comprises the distance between the WLAN positioning system location estimation and a region of possible solutions provided by the satellite positioning system measurements.
5. The method of claim 1, wherein the consistency of the internal SPS receiver clock for the WLAN based location estimate is used as an indication of consistency between the WLAN based location estimate and the satellite positioning system measurements.
6. A method of determining an expected error in a location determination of a WLAN and satellite enabled device, the method comprising:
determining a WLAN based location estimate and an expected error estimate for the WLAN location estimate;
determining a satellite based location estimate and an expected error estimate for the satellite based location estimate; and
determining the expected error of the location determination by evaluating the consistency of the satellite positioning system location estimate to the WLAN positioning system location estimation.
7. The method of claim 6, wherein the location estimate with the lower expected error is selected as the location of the WLAN and satellite enabled device.
8. The method of claim 6, wherein determining the expected error of the location determination comprises comparing the WLAN location estimate and the satellite positioning system location estimate.
9. The method of claim 6, wherein consistent measurements between the WLAN location estimate and the satellite positioning system location estimate result in a lower expected error in the location determination of the WLAN and satellite enabled device.
10. The method of claim 6, wherein inconsistent measurements between the WLAN location estimate and the satellite positioning system location estimate result in a higher expected error in the location determination of the WLAN and satellite enabled device.
11. The method of claim 6, wherein the consistency of the estimates comprises the distance between the satellite positioning system location estimate and the WLAN positioning system location estimation.
12. The method of claim 6, wherein the consistency of the internal SPS receiver clock for the WLAN based location estimate is used as an indication of consistency between the WLAN based location estimate and the satellite positioning system location.
13. A system for increasing the accuracy of a WLAN based position estimate using satellite positioning information, the system comprising:
a positioning module comprising:
a WLAN module for receiving information from one or more WLAN access points to calculate a WLAN location estimate;
a satellite positioning module for obtaining satellite information from at least two different satellites; and
logic located in the positioning module for determining the expected error of the location determination by evaluating the consistency of the satellite positioning system measurements to the WLAN positioning system location estimation.
14. The system of claim 13, wherein consistent measurements between the WLAN location estimate and the satellite positioning measurements result in a lower expected error in the location determination of the WLAN and satellite enabled device.
15. The system of claim 13, wherein inconsistent measurements between the WLAN location estimate and the satellite positioning system measurements result in a higher expected error in the location determination of the WLAN and satellite enabled device.
16. The system of claim 13, wherein consistency of the measurements comprises the distance between the WLAN positioning system location estimation and a region of possible solutions provided by the satellite positioning system measurements.
17. The system of claim 13, wherein the consistency of the internal SPS receiver clock for the WLAN based location estimate is used as an indication of consistency between the WLAN based location estimate and the satellite measurements.
18. A system for increasing the accuracy of a WLAN based position estimate using satellite positioning information, the system comprising:
a positioning module comprising:
a WLAN module for receiving information from one or more WLAN access points and to calculate a WLAN position estimate;
a satellite positioning module for obtaining satellite information from at least four different satellites to calculate a satellite position estimate; and
logic located in the positioning module for determining the expected error of the location determination by evaluating the consistency of the satellite positioning system location estimate to the WLAN positioning system location estimation.
19. The system of claim 18, wherein the consistency of the internal SPS receiver clock for the WLAN based position estimate is used as an indication of consistency between the WLAN based position estimate and the satellite position estimate.
20. The system of claim 18, wherein the position estimate with the lower expected error is selected as the location of the WLAN and satellite enabled device.
21. The system of claim 18, wherein determining the expected error of the location determination comprises comparing the WLAN location estimate and the satellite positioning system location estimate.
22. The system of claim 18, wherein consistent measurements between the WLAN location estimate and the satellite positioning system location estimate result in a lower expected error in the location determination of the WLAN and satellite enabled device.
23. The system of claim 18, wherein inconsistent measurements between the WLAN location estimate and the satellite positioning system location estimate result in a higher expected error in the location determination of the WLAN and satellite enabled device.
US12/479,727 2008-06-06 2009-06-05 Methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system Abandoned US20090303113A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US12/479,727 US20090303113A1 (en) 2008-06-06 2009-06-05 Methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US5958008P 2008-06-06 2008-06-06
US12/479,727 US20090303113A1 (en) 2008-06-06 2009-06-05 Methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system

Publications (1)

Publication Number Publication Date
US20090303113A1 true US20090303113A1 (en) 2009-12-10

Family

ID=41398570

Family Applications (9)

Application Number Title Priority Date Filing Date
US12/479,729 Active 2029-09-03 US8089398B2 (en) 2008-06-06 2009-06-05 Methods and systems for stationary user detection in a hybrid positioning system
US12/479,723 Active 2029-10-27 US8089399B2 (en) 2008-06-06 2009-06-05 System and method for refining a WLAN-PS estimated location using satellite measurements in a hybrid positioning system
US12/479,734 Active 2029-10-31 US7999742B2 (en) 2008-06-06 2009-06-05 System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system
US12/479,724 Active 2029-10-26 US8054219B2 (en) 2008-06-06 2009-06-05 Systems and methods for determining position using a WLAN-PS estimated position as an initial position in a hybrid positioning system
US12/479,718 Abandoned US20090303114A1 (en) 2008-06-06 2009-06-05 Method and system for determining location using a hybrid satellite and wlan positioning system by selecting the best wlan-ps solution
US12/479,722 Abandoned US20100052983A1 (en) 2008-06-06 2009-06-05 Systems and methods for maintaining clock bias accuracy in a hybrid positioning system
US12/479,721 Abandoned US20090303119A1 (en) 2008-06-06 2009-06-05 Systems and methods for using environmental information in a hybrid positioning system
US12/479,727 Abandoned US20090303113A1 (en) 2008-06-06 2009-06-05 Methods and systems for improving the accuracy of expected error estimation in a hybrid positioning system
US13/209,629 Active US8130148B2 (en) 2008-06-06 2011-08-15 System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system

Family Applications Before (7)

Application Number Title Priority Date Filing Date
US12/479,729 Active 2029-09-03 US8089398B2 (en) 2008-06-06 2009-06-05 Methods and systems for stationary user detection in a hybrid positioning system
US12/479,723 Active 2029-10-27 US8089399B2 (en) 2008-06-06 2009-06-05 System and method for refining a WLAN-PS estimated location using satellite measurements in a hybrid positioning system
US12/479,734 Active 2029-10-31 US7999742B2 (en) 2008-06-06 2009-06-05 System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system
US12/479,724 Active 2029-10-26 US8054219B2 (en) 2008-06-06 2009-06-05 Systems and methods for determining position using a WLAN-PS estimated position as an initial position in a hybrid positioning system
US12/479,718 Abandoned US20090303114A1 (en) 2008-06-06 2009-06-05 Method and system for determining location using a hybrid satellite and wlan positioning system by selecting the best wlan-ps solution
US12/479,722 Abandoned US20100052983A1 (en) 2008-06-06 2009-06-05 Systems and methods for maintaining clock bias accuracy in a hybrid positioning system
US12/479,721 Abandoned US20090303119A1 (en) 2008-06-06 2009-06-05 Systems and methods for using environmental information in a hybrid positioning system

Family Applications After (1)

Application Number Title Priority Date Filing Date
US13/209,629 Active US8130148B2 (en) 2008-06-06 2011-08-15 System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system

Country Status (7)

Country Link
US (9) US8089398B2 (en)
EP (1) EP2283641B1 (en)
JP (1) JP5775449B2 (en)
KR (1) KR101603810B1 (en)
CN (1) CN102100058A (en)
CA (1) CA2727038A1 (en)
WO (1) WO2009149417A1 (en)

Cited By (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070258420A1 (en) * 2006-05-08 2007-11-08 Farshid Alizadeh-Shabdiz Estimation of speed of travel using the dynamic signal strength variation of multiple WLAN access points
US20080008121A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of passive and active scanning of wlan-enabled access points to estimate position of a wlan positioning device
US20080108371A1 (en) * 2006-11-07 2008-05-08 Farshid Alizadeh-Shabdiz System and method for estimating positioning error within a wlan-based positioning system
US20080192696A1 (en) * 2005-07-25 2008-08-14 Joachim Sachs Handover Optimisation in a Wlan Radio Access Network
US20080248808A1 (en) * 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Estimation of position, speed and bearing using time difference of arrival and received signal strength in a wlan positioning system
US20080248741A1 (en) * 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Time difference of arrival based estimation of direction of travel in a wlan positioning system
US20090154371A1 (en) * 2006-05-08 2009-06-18 Skyhook Wireless, Inc. Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system
US20090303112A1 (en) * 2008-06-06 2009-12-10 Skyhook Wireless, Inc. System and method for refining a wlan-ps estimated location using satellite measurements in a hybrid positioning system
US20090312036A1 (en) * 2008-06-16 2009-12-17 Skyhook Wireless, Inc. Methods and systems for improving the accuracy of expected error estimation in location determinations using a hybrid cellular and wlan positioning system
US7769396B2 (en) 2004-10-29 2010-08-03 Skyhook Wireless, Inc. Location-based services that choose location algorithms based on number of detected access points within range of user device
US7835754B2 (en) 2006-05-08 2010-11-16 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system
US20110021207A1 (en) * 2009-07-24 2011-01-27 Morgan Edward J System and Method for Estimating Positioning Error Within a WLAN-Based Positioning System
US8022877B2 (en) 2009-07-16 2011-09-20 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US8063820B2 (en) 2009-07-16 2011-11-22 Skyhook Wireless, Inc. Methods and systems for determining location using a hybrid satellite and WLAN positioning system by selecting the best SPS measurements
US8103288B2 (en) 2006-05-08 2012-01-24 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations
US8140094B2 (en) 2005-02-22 2012-03-20 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US20120072110A1 (en) * 2010-09-17 2012-03-22 Atheros Communications, Inc. Indoor positioning using pressure sensors
US8200251B2 (en) 2010-01-15 2012-06-12 Apple Inc. Determining a location of a mobile device using a location database
US8279114B2 (en) 2009-10-02 2012-10-02 Skyhook Wireless, Inc. Method of determining position in a hybrid positioning system using a dilution of precision metric
US20130005356A1 (en) * 2010-01-07 2013-01-03 Nec Corporation Radio communication system, radio terminal, radio network, radio communication method and program
US8369264B2 (en) 2005-10-28 2013-02-05 Skyhook Wireless, Inc. Method and system for selecting and providing a relevant subset of Wi-Fi location information to a mobile client device so the client device may estimate its position with efficient utilization of resources
US8406785B2 (en) 2009-08-18 2013-03-26 Skyhook Wireless, Inc. Method and system for estimating range of mobile device to wireless installation
US8433334B2 (en) 2010-01-15 2013-04-30 Apple Inc. Managing a location database for network-based positioning system
US8504059B2 (en) 2010-01-15 2013-08-06 Apple Inc. Location filtering using mobile country code
US8559974B2 (en) 2010-06-11 2013-10-15 Skyhook Wireless, Inc. Methods of and systems for measuring beacon stability of wireless access points
US8606294B2 (en) 2010-10-05 2013-12-10 Skyhook Wireless, Inc. Method of and system for estimating temporal demographics of mobile users
US8619643B2 (en) 2010-03-24 2013-12-31 Skyhook Wireless, Inc. System and method for estimating the probability of movement of access points in a WLAN-based positioning system
US8620344B2 (en) 2010-04-07 2013-12-31 Apple Inc. Location-based application program management
US8634860B2 (en) 2010-01-15 2014-01-21 Apple Inc. Location determination using cached location area codes
US8638256B2 (en) 2009-09-29 2014-01-28 Skyhook Wireless, Inc. Accuracy and performance of a hybrid positioning system
US8655371B2 (en) 2010-01-15 2014-02-18 Apple Inc. Location determination using cached location area codes
US8660576B2 (en) 2010-01-15 2014-02-25 Apple Inc. Adaptive location determination
US8890746B2 (en) 2010-11-03 2014-11-18 Skyhook Wireless, Inc. Method of and system for increasing the reliability and accuracy of location estimation in a hybrid positioning system
US9008061B2 (en) 2010-05-26 2015-04-14 Ntt Docomo, Inc. Positioning device and positioning method
US9298897B2 (en) 2011-06-22 2016-03-29 Skyhook Wireless, Inc. Method of and systems for privacy preserving mobile demographic measurement of individuals, groups and locations over time and space
US9363785B2 (en) 2006-05-08 2016-06-07 Skyhook Wireless, Inc. Calculation of quality of WLAN access point characterization for use in a WLAN positioning system
CN105988128A (en) * 2015-03-20 2016-10-05 福特全球技术公司 Vehicle location accuracy
US9635510B1 (en) 2016-06-24 2017-04-25 Athentek Innovations, Inc. Database for Wi-Fi position estimation
US9730079B2 (en) 2012-04-16 2017-08-08 Zte Corporation Joint positioning method and device

Families Citing this family (130)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080234558A1 (en) * 2007-03-20 2008-09-25 Cogito Health Inc. Methods and systems for performing a clinical assessment
US20080291086A1 (en) * 2007-05-25 2008-11-27 Broadcom Corporation Position determination using available positioning techniques
US20090189810A1 (en) * 2008-01-24 2009-07-30 Broadcom Corporation Weighted aiding for positioning systems
US8645053B2 (en) * 2008-07-16 2014-02-04 Autotalks Ltd. Relative vehicular positioning using vehicular communications
US9781148B2 (en) 2008-10-21 2017-10-03 Lookout, Inc. Methods and systems for sharing risk responses between collections of mobile communications devices
US9235704B2 (en) 2008-10-21 2016-01-12 Lookout, Inc. System and method for a scanning API
US8108933B2 (en) 2008-10-21 2012-01-31 Lookout, Inc. System and method for attack and malware prevention
US8051480B2 (en) 2008-10-21 2011-11-01 Lookout, Inc. System and method for monitoring and analyzing multiple interfaces and multiple protocols
US9367680B2 (en) 2008-10-21 2016-06-14 Lookout, Inc. System and method for mobile communication device application advisement
US8347386B2 (en) 2008-10-21 2013-01-01 Lookout, Inc. System and method for server-coupled malware prevention
US8060936B2 (en) 2008-10-21 2011-11-15 Lookout, Inc. Security status and information display system
US8087067B2 (en) 2008-10-21 2011-12-27 Lookout, Inc. Secure mobile platform system
US8533844B2 (en) 2008-10-21 2013-09-10 Lookout, Inc. System and method for security data collection and analysis
US9043919B2 (en) 2008-10-21 2015-05-26 Lookout, Inc. Crawling multiple markets and correlating
US8984628B2 (en) 2008-10-21 2015-03-17 Lookout, Inc. System and method for adverse mobile application identification
FR2942097A1 (en) * 2009-02-06 2010-08-13 Thomson Licensing TRANSMITTING METHOD IN A WIRELESS NETWORK AND CORRESPONDING RECEIVING METHOD
US8855601B2 (en) 2009-02-17 2014-10-07 Lookout, Inc. System and method for remotely-initiated audio communication
US9955352B2 (en) 2009-02-17 2018-04-24 Lookout, Inc. Methods and systems for addressing mobile communications devices that are lost or stolen but not yet reported as such
US9042876B2 (en) 2009-02-17 2015-05-26 Lookout, Inc. System and method for uploading location information based on device movement
US8467768B2 (en) 2009-02-17 2013-06-18 Lookout, Inc. System and method for remotely securing or recovering a mobile device
US8538815B2 (en) 2009-02-17 2013-09-17 Lookout, Inc. System and method for mobile device replacement
FR2945176B1 (en) * 2009-04-30 2012-07-20 Pole Star Sa METHOD OF POSITIONING BY WI-FI SIGNALS
US8427977B2 (en) 2009-06-23 2013-04-23 CSC Holdings, LLC Wireless network polling and data warehousing
US20110080318A1 (en) * 2009-10-02 2011-04-07 Skyhook Wireless, Inc. Determining A Dilution of Precision Metric Using Two or Three GPS Satellites
CA2776890C (en) * 2009-10-06 2018-04-10 Rfid Mexico S.A. De C.V. Geographical localization system
US8397301B2 (en) 2009-11-18 2013-03-12 Lookout, Inc. System and method for identifying and assessing vulnerabilities on a mobile communication device
US8199051B2 (en) 2009-12-18 2012-06-12 Trueposition, Inc. Satellite positioning receiver and proxy location system
US8634359B2 (en) 2009-12-23 2014-01-21 Sensewhere Limited Locating electromagnetic signal sources
US20110207472A1 (en) * 2010-02-19 2011-08-25 Charles Abraham Method and system for cellular clock-assisted wireless access point locating
US8531332B2 (en) * 2010-03-22 2013-09-10 Qualcomm Incorporated Anti-spoofing detection system
WO2011128722A1 (en) * 2010-04-12 2011-10-20 Nokia Corporation Selection of a relative positioning method
JP5081274B2 (en) * 2010-05-25 2012-11-28 株式会社エヌ・ティ・ティ・ドコモ Mobile communication terminal and positioning method selection method
KR101440836B1 (en) * 2010-07-08 2014-11-04 에스케이텔레콤 주식회사 Method And Apparatus for Detecting Positioning Error by Using WLAN Signal
US8339316B1 (en) 2010-08-13 2012-12-25 Google Inc. Smart GPS use
US8924155B2 (en) * 2010-09-13 2014-12-30 Texas Instruments Incorporated System and method for access point based positioning
WO2012055026A1 (en) 2010-10-26 2012-05-03 Rx Networks Inc. Method and apparatus for determining a position of a gnss receiver
WO2012069686A1 (en) 2010-11-24 2012-05-31 Crambo, S.A. Communication system and method involving the creation of virtual spaces
US20120172054A1 (en) * 2011-01-05 2012-07-05 Texas Instruments Incorporated System and method for cooperative positioning
US9081080B2 (en) 2011-03-04 2015-07-14 Qualcomm Incorporated RSSI-based indoor positioning in the presence of dynamic transmission power control access points
US8391889B2 (en) 2011-06-03 2013-03-05 Apple Inc. Altitude estimation using a probability density function
CN102821461A (en) * 2011-06-07 2012-12-12 深圳市嘀咕网科技有限公司 Method and system for position judgment and corresponding mobile terminals
US8738765B2 (en) 2011-06-14 2014-05-27 Lookout, Inc. Mobile device DNS optimization
CA2840250C (en) * 2011-06-30 2019-05-21 Trusted Positioning Inc. An improved system and method for wireless positioning in wireless network-enabled environments
US8788881B2 (en) 2011-08-17 2014-07-22 Lookout, Inc. System and method for mobile device push communications
US9535154B2 (en) * 2011-09-12 2017-01-03 Microsoft Technology Licensing, Llc Cache-based location determination
JP2013101085A (en) * 2011-11-10 2013-05-23 Hitachi Kokusai Electric Inc Mobile station device
US8675535B2 (en) * 2012-01-11 2014-03-18 Qualcomm Incorporated Reducing power consumption in a mobile communication device in response to motion detection
US8700057B2 (en) * 2012-01-13 2014-04-15 Qualcomm Incorporated Method and apparatus for multi-resolution adaptive positioning
GB201200831D0 (en) 2012-01-18 2012-02-29 Sensewhere Ltd Improved positioning system
US8611247B2 (en) * 2012-01-24 2013-12-17 Qualcomm Incorporated Dynamic data retrieval in a WLAN positioning system
US9973884B2 (en) 2012-03-07 2018-05-15 Intel Corporation Device, system and method of controlling access to location sources
WO2013142946A1 (en) 2012-03-29 2013-10-03 Rx Networks Inc. Method and apparatus for determining a position of a gnss receiver
KR101642213B1 (en) * 2012-03-29 2016-07-22 인텔 코포레이션 Device, system and method of location estimation of a mobile device
US9645242B2 (en) 2012-04-10 2017-05-09 Intel Corporation Device, system and method of collaborative location error correction
US9103916B2 (en) * 2012-05-02 2015-08-11 Texas Instruments Incorporated Apparatus and method for indoor positioning
CN103428629B (en) * 2012-05-18 2016-12-14 中国电信股份有限公司 Mixed positioning realization method and system
US9407443B2 (en) 2012-06-05 2016-08-02 Lookout, Inc. Component analysis of software applications on computing devices
US9589129B2 (en) 2012-06-05 2017-03-07 Lookout, Inc. Determining source of side-loaded software
WO2013188597A2 (en) 2012-06-12 2013-12-19 Amrit Bandyopadhyay Irregular feature mapping
US8655307B1 (en) 2012-10-26 2014-02-18 Lookout, Inc. System and method for developing, updating, and using user device behavioral context models to modify user, device, and application state, settings and behavior for enhanced user security
US9208215B2 (en) 2012-12-27 2015-12-08 Lookout, Inc. User classification based on data gathered from a computing device
US8738035B1 (en) * 2012-12-27 2014-05-27 Texas Instruments Incorporated System and method for hybrid positioning using Wi-Fi and GNSS blending
US9374369B2 (en) 2012-12-28 2016-06-21 Lookout, Inc. Multi-factor authentication and comprehensive login system for client-server networks
US8855599B2 (en) 2012-12-31 2014-10-07 Lookout, Inc. Method and apparatus for auxiliary communications with mobile communications device
US9424409B2 (en) 2013-01-10 2016-08-23 Lookout, Inc. Method and system for protecting privacy and enhancing security on an electronic device
US20140199959A1 (en) * 2013-01-14 2014-07-17 Microsoft Corporation Location determination for emergency services in wireless networks
US9179265B2 (en) 2013-01-31 2015-11-03 Apple Inc. Reducing location search space
US9198003B2 (en) 2013-01-31 2015-11-24 Apple Inc. Survey techniques for generating location fingerprint data
US9191908B2 (en) * 2013-03-05 2015-11-17 Qualcomm Incorporated Reducing impact of clock drift in wireless devices
US9933526B2 (en) 2013-03-15 2018-04-03 Nextnav, Llc Techniques to improve the performance of a fixed, timing-based radio positioning network using external assistance information
US9976860B2 (en) 2013-04-16 2018-05-22 Apple Inc. Seamless transition from outdoor to indoor mapping
US9460388B2 (en) 2013-05-30 2016-10-04 Apple Inc. Range class estimation for radio frequency devices
US20150045022A1 (en) * 2013-08-06 2015-02-12 Gaby Prechner Access points and methods for access point selection using an information data structure
US9642008B2 (en) 2013-10-25 2017-05-02 Lookout, Inc. System and method for creating and assigning a policy for a mobile communications device based on personal data
US9753796B2 (en) 2013-12-06 2017-09-05 Lookout, Inc. Distributed monitoring, evaluation, and response for multiple devices
US10122747B2 (en) 2013-12-06 2018-11-06 Lookout, Inc. Response generation after distributed monitoring and evaluation of multiple devices
US9820093B2 (en) 2013-12-20 2017-11-14 Apple Inc. Programmable beacon payloads
EP3123793B1 (en) * 2014-03-28 2020-05-20 Intel IP Corporation Method and apparatus for wi-fi location determination
KR102280610B1 (en) 2014-04-24 2021-07-23 삼성전자주식회사 Method and apparatus for location estimation of electronic device
US9863773B2 (en) 2014-04-29 2018-01-09 Samsung Electronics Co., Ltd. Indoor global positioning system
US20150330795A1 (en) * 2014-05-15 2015-11-19 Qualcomm Incorporated Method to Dynamically Adjust Assistance Data for Improved Indoor Positioning Performance
US9439043B2 (en) * 2014-05-16 2016-09-06 Google Inc. Running location provider processes
US11310367B2 (en) * 2014-05-20 2022-04-19 Time Warner Cable Enterprises Llc Wireless network installation analyzer and reporting
US10664856B2 (en) 2014-05-21 2020-05-26 Apple Inc. Beacon-triggered code redemption for mobile devices
US9949200B2 (en) 2014-05-27 2018-04-17 Apple Inc. Centralized beacon management service
US10108748B2 (en) 2014-05-30 2018-10-23 Apple Inc. Most relevant application recommendation based on crowd-sourced application usage data
US9769622B2 (en) 2014-05-30 2017-09-19 Apple Inc. Indoor location survey assisted by a motion path on a venue map
US9913100B2 (en) 2014-05-30 2018-03-06 Apple Inc. Techniques for generating maps of venues including buildings and floors
US9304185B2 (en) 2014-05-31 2016-04-05 Apple Inc. Deduplicating location fingerprint data
US9491585B2 (en) 2014-05-31 2016-11-08 Apple Inc. Location determination using dual statistical filters
US9720091B2 (en) 2014-06-30 2017-08-01 Honeywell International Inc. Adaptive satellite search succession
CN105282698B (en) * 2014-07-10 2020-11-03 中兴通讯股份有限公司 Method and system for acquiring GPS signal
US9998867B2 (en) 2014-09-29 2018-06-12 Apple Inc. Content discovery using beacons
US10111030B2 (en) 2014-09-29 2018-10-23 Apple Inc. Beacon applications for content discovery and interaction
US9456416B2 (en) 2014-09-30 2016-09-27 Apple Inc. Scoring beacon messages for mobile device wake-up
US9426615B2 (en) 2014-09-30 2016-08-23 Apple Inc. Prioritizing beacon messages for mobile devices
US10210561B2 (en) 2014-09-30 2019-02-19 Apple Inc. Beacon triggered device to device content transfer
US10296950B2 (en) 2014-09-30 2019-05-21 Apple Inc. Beacon triggered processes
CN105807700B (en) * 2014-12-30 2020-07-17 芯讯通无线科技(上海)有限公司 Vehicle-mounted monitoring equipment
WO2016139615A1 (en) * 2015-03-04 2016-09-09 Universita' Degli Studi Di Genova Method and system for real-time location
WO2016144298A1 (en) * 2015-03-06 2016-09-15 Hewlett Packard Enterprise Development Lp Location update scheduling
US9781569B2 (en) * 2015-03-12 2017-10-03 GM Global Technology Operations LLC Systems and methods for resolving positional ambiguities using access point information
WO2016178816A1 (en) 2015-05-01 2016-11-10 Lookout, Inc. Determining source of side-loaded software
US9838848B2 (en) 2015-06-05 2017-12-05 Apple Inc. Venue data prefetch
US9918203B2 (en) 2015-06-05 2018-03-13 Apple Inc. Correcting in-venue location estimation using structural information
US9936342B2 (en) 2015-06-05 2018-04-03 Apple Inc. Floor level determination
US9578459B2 (en) 2015-06-05 2017-02-21 Qualcomm Incorporated Hybrid positioning techniques based on RTT and TOA/TDOA
US9681267B2 (en) 2015-06-24 2017-06-13 Apple Inc. Positioning techniques for narrowband wireless signals under dense multipath conditions
US9823079B2 (en) 2015-09-29 2017-11-21 Apple Inc. Polygonal routing
JP6593879B2 (en) 2016-03-24 2019-10-23 日本電気株式会社 Satellite positioning system, positioning terminal, positioning method, and program
WO2018148004A1 (en) * 2017-02-08 2018-08-16 Nextnav, Llc Systems and methods for estimating a position of a receiver
US10794986B2 (en) 2017-06-02 2020-10-06 Apple Inc. Extending a radio map
US10979854B2 (en) 2017-06-02 2021-04-13 Apple Inc. Extending a radio map
US10477609B2 (en) 2017-06-02 2019-11-12 Apple Inc. Healing a radio map
US10218697B2 (en) 2017-06-09 2019-02-26 Lookout, Inc. Use of device risk evaluation to manage access to services
US11582576B2 (en) 2018-06-01 2023-02-14 Apple Inc. Feature-based slam
US11122441B2 (en) 2018-06-08 2021-09-14 Microsoft Technology Licensing, Llc Anomalous access point detection
CN108966127B (en) * 2018-07-18 2021-03-30 广东小天才科技有限公司 Positioning deviation rectifying method and positioning server combining Wi-Fi fingerprint and satellite positioning
JP7211040B2 (en) 2018-11-29 2023-01-24 富士通株式会社 POSITION DETECTION SYSTEM, POSITION DETECTION DEVICE, POSITION DETECTION METHOD, AND SENSOR TERMINAL
JP2021001833A (en) * 2019-06-24 2021-01-07 アライドテレシスホールディングス株式会社 Position estimating device and method
US11622234B2 (en) 2019-09-13 2023-04-04 Troverlo, Inc. Passive asset tracking using observations of Wi-Fi access points
US11917488B2 (en) 2019-09-13 2024-02-27 Troverlo, Inc. Passive asset tracking using observations of pseudo Wi-Fi access points
US11589187B2 (en) 2019-09-13 2023-02-21 Troverlo, Inc. Passive sensor tracking using observations of Wi-Fi access points
CN112578334A (en) 2019-09-27 2021-03-30 中光电智能机器人股份有限公司 Unmanned aerial vehicle and positioning method thereof, unmanned aerial vehicle communication system and operation method thereof
CN110823176A (en) * 2019-11-14 2020-02-21 广西电网有限责任公司电力科学研究院 Method, equipment and medium for monitoring inclined settlement of transformer substation enclosure wall
CN111239777B (en) * 2020-01-07 2023-07-25 哈尔滨工业大学 Satellite cluster hierarchical positioning method based on position fingerprint
FR3108398B1 (en) * 2020-03-19 2022-02-25 Psa Automobiles Sa Method and system for determining the location of a motor vehicle
CN111510409B (en) * 2020-04-16 2020-12-29 清华大学 Method and system for estimating space-based opportunistic signal doppler using BPSK data
FI20206326A1 (en) * 2020-12-17 2022-06-18 Nokia Technologies Oy Estimating positioning integrity
US20230143872A1 (en) * 2021-11-09 2023-05-11 Msrs Llc Method, apparatus, and computer readable medium for a multi-source reckoning system

Citations (79)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5420592A (en) * 1993-04-05 1995-05-30 Radix Technologies, Inc. Separated GPS sensor and processing system for remote GPS sensing and centralized ground station processing for remote mobile position and velocity determinations
US6185427B1 (en) * 1996-09-06 2001-02-06 Snaptrack, Inc. Distributed satellite position system processing and application network
US6262741B1 (en) * 1998-03-17 2001-07-17 Prc Public Sector, Inc. Tiling of object-based geographic information system (GIS)
US20020055956A1 (en) * 2000-09-08 2002-05-09 Krasnoiarov Boris Andreyevich Method and system for assembling concurrently-generated content
US6420999B1 (en) * 2000-10-26 2002-07-16 Qualcomm, Inc. Method and apparatus for determining an error estimate in a hybrid position determination system
US20030011511A1 (en) * 1999-11-12 2003-01-16 King Thomas M. Method and apparatus for assisted GPS
US20030043073A1 (en) * 2001-09-05 2003-03-06 Gray Matthew K. Position detection and location tracking in a wireless network
US6574557B2 (en) * 2001-04-27 2003-06-03 Pioneer Corporation Positioning error range setting apparatus, method, and navigation apparatus
US6587692B1 (en) * 2000-03-30 2003-07-01 Lucent Technologies Inc. Location determination using weighted ridge regression
US20030125045A1 (en) * 2001-12-27 2003-07-03 Riley Wyatt Thomas Creating and using base station almanac information in a wireless communication system having a position location capability
US6678611B2 (en) * 1998-03-25 2004-01-13 Navigation Technologies Corp. Method and system for route calculation in a navigation application
US20040019679A1 (en) * 2002-07-24 2004-01-29 Sandhya E First thread lock management for distributed data systems
US20040023669A1 (en) * 2002-07-31 2004-02-05 Interdigital Technology Corporation Handover between a cellular system and a wireless local area network
US6707422B2 (en) * 1998-07-02 2004-03-16 Snaptrack Incorporated Method and apparatus for measurement processing of satellite positioning system (SPS) signals
US6725158B1 (en) * 1999-07-12 2004-04-20 Skybitz, Inc. System and method for fast acquisition reporting using communication satellite range measurement
US20040081133A1 (en) * 2002-10-25 2004-04-29 Nattavut Smavatkul Method of communication device initiated frame exchange
US20040087317A1 (en) * 2002-10-30 2004-05-06 Lockheed Martin Corporation Cooperative element location system
US6741188B1 (en) * 1999-10-22 2004-05-25 John M. Miller System for dynamically pushing information to a user utilizing global positioning system
US20050020266A1 (en) * 2003-02-24 2005-01-27 Floyd Backes Distance determination apparatus for use by devices in a wireless network
US20050017898A1 (en) * 2003-06-03 2005-01-27 Koichiro Teranishi Positional information determining apparatus
US20050037775A1 (en) * 2003-06-27 2005-02-17 Mark Moeglein Method and apparatus for wireless network hybrid positioning
US20050090266A1 (en) * 2003-06-27 2005-04-28 Leonid Sheynblat Local area network assisted positioning
US6888811B2 (en) * 2001-09-24 2005-05-03 Motorola, Inc. Communication system for location sensitive information and method therefor
US6894645B1 (en) * 2003-12-11 2005-05-17 Nokia Corporation Position estimation
US20060009235A1 (en) * 2004-06-18 2006-01-12 Leonid Sheynblat Method and apparatus for determining location of a base station using a plurality of mobile stations in a wireless mobile network
US20060040640A1 (en) * 2004-04-05 2006-02-23 Demetrius Thompson Cellular telephone safety system
US20060046709A1 (en) * 2004-06-29 2006-03-02 Microsoft Corporation Proximity detection using wireless signal strengths
US20060078122A1 (en) * 2003-03-25 2006-04-13 Dacosta Behram M Location-based wireless messaging for wireless devices
US20060089157A1 (en) * 2004-10-27 2006-04-27 Qwest Communications International Inc. Mobile caching and data relay vectoring systems and methods
US20060089160A1 (en) * 2003-08-11 2006-04-27 Core Mobility, Inc. Systems and methods for displaying location-based maps on communication devices
US20060095348A1 (en) * 2004-10-29 2006-05-04 Skyhook Wireless, Inc. Server for updating location beacon database
US20070004427A1 (en) * 2005-02-22 2007-01-04 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US7167715B2 (en) * 2002-05-17 2007-01-23 Meshnetworks, Inc. System and method for determining relative positioning in AD-HOC networks
US7167716B2 (en) * 2002-02-08 2007-01-23 Curitel Communications, Inc. Synchronous demodulation apparatus of base transceiver station in interim standard-2000 system
US20070052583A1 (en) * 2005-09-08 2007-03-08 Topcon Gps, Llc Position determination using carrier phase measurements of satellite signals
US20070100955A1 (en) * 2005-10-29 2007-05-03 Bodner Oran J System and method for using known geographic locations of Internet users to present local content to web pages
US20070097511A1 (en) * 2005-10-28 2007-05-03 Cymer, Inc. Systems and methods for generating laser light shaped as a line beam
US20070109184A1 (en) * 2005-11-15 2007-05-17 Shyr You-Yuh J Novas hybrid positioning technology using terrestrial digital broadcasting signal (DBS) and global positioning system (GPS) satellite signal
US7221928B2 (en) * 2003-10-01 2007-05-22 Laird Mark D Mobile emergency notification system
US20070121560A1 (en) * 2005-11-07 2007-05-31 Edge Stephen W Positioning for wlans and other wireless networks
US20070126635A1 (en) * 2005-02-03 2007-06-07 Cyril Houri System and Method for Determining Geographic Location of Wireless Computing Devices
US7236126B2 (en) * 2004-12-13 2007-06-26 Samsung Electronics Co., Ltd. AGPS system using NTP server and method for determining the location of a terminal using a NTP server
US20070150516A1 (en) * 2005-11-23 2007-06-28 Morgan Edward J Location toolbar for internet search and communication
US20070167174A1 (en) * 2006-01-19 2007-07-19 Halcrow Michael A On-device mapping of WIFI hotspots via direct connection of WIFI-enabled and GPS-enabled mobile devices
US7250907B2 (en) * 2003-06-30 2007-07-31 Microsoft Corporation System and methods for determining the location dynamics of a portable computing device
US20080004888A1 (en) * 2006-06-29 2008-01-03 Microsoft Corporation Wireless, location-based e-commerce for mobile communication devices
US20080008120A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of improving sampling of wlan packet information to improve estimates of doppler frequency of a wlan positioning device
US20080033646A1 (en) * 2006-08-04 2008-02-07 Morgan Edward J Systems and Methods of Automated Retrieval of Location Information from a User Device for use with Server Systems
US20080032706A1 (en) * 2006-08-01 2008-02-07 Leonid Sheynblat System And/Or Method For Providing Information Updates To A Location Server
US20080079633A1 (en) * 2006-08-23 2008-04-03 Qualcomm Incorporated System and/or method for reducing ambiguities in received sps signals
US20080108371A1 (en) * 2006-11-07 2008-05-08 Farshid Alizadeh-Shabdiz System and method for estimating positioning error within a wlan-based positioning system
US20080111737A1 (en) * 2006-11-15 2008-05-15 Motorola Inc. Method and system for hybrid location aiding for multi-mode devices
US20080133336A1 (en) * 2006-06-01 2008-06-05 Altman Samuel H Location-Based Advertising Message Serving For Mobile Communication Devices
US20080158053A1 (en) * 2006-12-05 2008-07-03 Alpine Electronics, Inc. GPS Position Measuring Device
US7397424B2 (en) * 2005-02-03 2008-07-08 Mexens Intellectual Property Holding, Llc System and method for enabling continuous geographic location estimation for wireless computing devices
US20080176583A1 (en) * 2005-10-28 2008-07-24 Skyhook Wireless, Inc. Method and system for selecting and providing a relevant subset of wi-fi location information to a mobile client device so the client device may estimate its position with efficient utilization of resources
US20090002237A1 (en) * 2007-06-27 2009-01-01 Motorola, Inc. Method and device for determining a position of a portable electronic device
US20090042557A1 (en) * 2007-02-05 2009-02-12 Wefi, Inc. System and Method For Mapping Wireless Access Points
US7502620B2 (en) * 2005-03-04 2009-03-10 Shyhook Wireless, Inc. Encoding and compression of a location beacon database
US7515578B2 (en) * 2006-05-08 2009-04-07 Skyhook Wireless, Inc. Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system
US20090121927A1 (en) * 2007-11-14 2009-05-14 Radiofy Llc Systems and Methods of Assisted GPS
US7545894B2 (en) * 2004-03-19 2009-06-09 Purdue Research Foundation Method and apparatus for detecting and processing global positioning system (GPS) signals
US7551929B2 (en) * 2006-05-08 2009-06-23 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations
US7551579B2 (en) * 2006-05-08 2009-06-23 Skyhook Wireless, Inc. Calculation of quality of wlan access point characterization for use in a wlan positioning system
US20090161806A1 (en) * 2007-12-19 2009-06-25 Apple Inc. Microcontroller clock calibration using data transmission from an accurate third party
US20090168843A1 (en) * 2007-10-03 2009-07-02 Texas Instruments Incorporated Power-saving receiver circuits, systems and processes
US20090181695A1 (en) * 2008-01-14 2009-07-16 Nokia Corporation Use of movement information about a wireless client
US7664511B2 (en) * 2005-12-12 2010-02-16 Nokia Corporation Mobile location method for WLAN-type systems
US20100039323A1 (en) * 2008-08-12 2010-02-18 Andrei Kosolobov Method and system for global position reference map (gprm) for agps
US20100052983A1 (en) * 2008-06-06 2010-03-04 Skyhook Wireless, Inc. Systems and methods for maintaining clock bias accuracy in a hybrid positioning system
US7724612B2 (en) * 2007-04-20 2010-05-25 Sirf Technology, Inc. System and method for providing aiding information to a satellite positioning system receiver over short-range wireless connections
US20110012784A1 (en) * 2009-07-16 2011-01-20 Skyhook Wireless, Inc. Methods and systems for determining location using a hybrid satellite and wlan positioning system by selecting the best sps measurements
US20110012780A1 (en) * 2009-07-16 2011-01-20 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved wlan access points
US20110021207A1 (en) * 2009-07-24 2011-01-27 Morgan Edward J System and Method for Estimating Positioning Error Within a WLAN-Based Positioning System
US20110045840A1 (en) * 2009-08-18 2011-02-24 Skyhook Wireless, Inc. Method and system for estimating range of mobile device to wireless installation
US20110058495A1 (en) * 2006-05-08 2011-03-10 Skyhook Wireless, Inc. Estimation of Speed and Direction of Travel in a WLAN Positioning System
US20110074626A1 (en) * 2009-09-29 2011-03-31 Skyhook Wireless, Inc. Improvement of the accuracy and performance of a hybrid positioning system
US20110080317A1 (en) * 2009-10-02 2011-04-07 Skyhook Wireless, Inc. Method of determining position in a hybrid positioning system using a dilution of precision metric
US20110080318A1 (en) * 2009-10-02 2011-04-07 Skyhook Wireless, Inc. Determining A Dilution of Precision Metric Using Two or Three GPS Satellites

Family Cites Families (62)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5936572A (en) * 1994-02-04 1999-08-10 Trimble Navigation Limited Portable hybrid location determination system
US5943606A (en) * 1996-09-30 1999-08-24 Qualcomm Incorporated Determination of frequency offsets in communication systems
US6006260A (en) * 1997-06-03 1999-12-21 Keynote Systems, Inc. Method and apparatus for evalutating service to a user over the internet
US5999124A (en) 1998-04-22 1999-12-07 Snaptrack, Inc, Satellite positioning system augmentation with wireless communication signals
JP2000029521A (en) * 1998-07-08 2000-01-28 Fuji Heavy Ind Ltd Autonomous traveling method and autonomously traveling vehicle
US6321090B1 (en) 1998-11-06 2001-11-20 Samir S. Soliman Mobile communication system with position detection to facilitate hard handoff
JP3571962B2 (en) * 1999-05-28 2004-09-29 日本電信電話株式会社 Position detection method
FI19992236A (en) 1999-10-15 2001-04-16 Nokia Networks Oy Location determination in a telecommunications network
US6665658B1 (en) 2000-01-13 2003-12-16 International Business Machines Corporation System and method for automatically gathering dynamic content and resources on the world wide web by stimulating user interaction and managing session information
JP2001235337A (en) * 2000-02-22 2001-08-31 Japan Aviation Electronics Industry Ltd Mobile station positioning device using mobile communication and mobile station positioning device using both mobile communication and gps satellite navigation
US7917390B2 (en) 2000-06-09 2011-03-29 Sony Corporation System and method for providing customized advertisements over a network
US7373425B2 (en) 2000-08-22 2008-05-13 Conexant Systems, Inc. High-speed MAC address search engine
JP2002281540A (en) 2001-03-19 2002-09-27 Hitachi Ltd Mobile terminal equipment for measuring position
US6594483B2 (en) * 2001-05-15 2003-07-15 Nokia Corporation System and method for location based web services
US6771211B2 (en) 2001-11-13 2004-08-03 Nokia Corporation Method, system and devices for positioning a receiver
US7606938B2 (en) 2002-03-01 2009-10-20 Enterasys Networks, Inc. Verified device locations in a data network
US20040203847A1 (en) 2002-03-28 2004-10-14 Knauerhase Robert C. Location-based task notification
JP4093792B2 (en) 2002-04-18 2008-06-04 富士通株式会社 Positioning system, program and position determining method for determining position of mobile radio station
US7532895B2 (en) * 2002-05-20 2009-05-12 Air Defense, Inc. Systems and methods for adaptive location tracking
US7660588B2 (en) * 2002-10-17 2010-02-09 Qualcomm Incorporated Method and apparatus for improving radio location accuracy with measurements
US7130646B2 (en) 2003-02-14 2006-10-31 Atheros Communications, Inc. Positioning with wireless local area networks and WLAN-aided global positioning systems
JP2004251714A (en) * 2003-02-19 2004-09-09 Mitsubishi Electric Corp Positioning device
US7313402B1 (en) 2003-06-24 2007-12-25 Verizon Corporate Services Group Inc. System and method for evaluating accuracy of an automatic location identification system
BRPI0411911B1 (en) 2003-06-27 2020-11-03 Qualcomm Incorporated method and equipment for hybrid wireless network positioning
US7123928B2 (en) 2003-07-21 2006-10-17 Qualcomm Incorporated Method and apparatus for creating and using a base station almanac for position determination
JPWO2005012939A1 (en) * 2003-07-31 2007-09-27 日本電気株式会社 Terminal positioning method and system
GB2405276B (en) 2003-08-21 2005-10-12 Motorola Inc Measuring distance using wireless communication
US6965576B1 (en) * 2004-04-21 2005-11-15 Telcordia Technologies, Inc. Automatic configuration of WLAN for mobile users
US7209077B2 (en) 2004-06-29 2007-04-24 Andrew Corporation Global positioning system signal acquisition assistance
US7881905B2 (en) * 2004-11-17 2011-02-01 Qualcomm Incorporated Method for ambiguity resolution in location determination
US7254405B2 (en) 2004-11-22 2007-08-07 Motorola, Inc. System and method for providing location information to applications
US7479922B2 (en) 2005-03-31 2009-01-20 Deere & Company Method and system for determining the location of a vehicle
US20060221918A1 (en) 2005-04-01 2006-10-05 Hitachi, Ltd. System, method and computer program product for providing content to a remote device
US7587081B2 (en) 2005-09-28 2009-09-08 Deere & Company Method for processing stereo vision data using image density
US7471954B2 (en) 2006-02-24 2008-12-30 Skyhook Wireless, Inc. Methods and systems for estimating a user position in a WLAN positioning system based on user assigned access point locations
JP4768494B2 (en) 2006-03-31 2011-09-07 テルモ株式会社 Diagnostic imaging apparatus and processing method thereof
US8014788B2 (en) * 2006-05-08 2011-09-06 Skyhook Wireless, Inc. Estimation of speed of travel using the dynamic signal strength variation of multiple WLAN access points
US7656348B2 (en) * 2006-05-19 2010-02-02 Qualcomm Incorporated System and/or method for determining sufficiency of pseudorange measurements
FI118394B (en) * 2006-05-26 2007-10-31 Savcor One Oy A system and method for locating a GPS device
US7925278B2 (en) 2006-06-27 2011-04-12 Motorola Mobility, Inc. Method and system for locating a wireless device in a wireless communication network
JP2008020926A (en) * 2006-07-11 2008-01-31 Magna Internatl Inc Light pipe with minimized thermal expansion effect
US7683835B2 (en) 2006-08-15 2010-03-23 Computer Associates Think, Inc. System and method for locating wireless devices
US7822427B1 (en) 2006-10-06 2010-10-26 Sprint Spectrum L.P. Method and system for using a wireless signal received via a repeater for location determination
US8314736B2 (en) 2008-03-31 2012-11-20 Golba Llc Determining the position of a mobile device using the characteristics of received signals and a reference database
US7848733B2 (en) 2006-12-28 2010-12-07 Trueposition, Inc. Emergency wireless location system including a location determining receiver
US20080234533A1 (en) * 2007-03-21 2008-09-25 Precision Innovations Llc System for evaluating an environment
US20080248808A1 (en) * 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Estimation of position, speed and bearing using time difference of arrival and received signal strength in a wlan positioning system
US20080248741A1 (en) 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Time difference of arrival based estimation of direction of travel in a wlan positioning system
US8103285B2 (en) 2007-04-19 2012-01-24 Kyocera Corporation Apparatus, system and method for determining a geographical location of a portable communication device
US20080291086A1 (en) * 2007-05-25 2008-11-27 Broadcom Corporation Position determination using available positioning techniques
US8307414B2 (en) * 2007-09-07 2012-11-06 Deutsche Telekom Ag Method and system for distributed, localized authentication in the framework of 802.11
US7595754B2 (en) 2007-12-24 2009-09-29 Qualcomm Incorporated Methods, systems and apparatus for integrated wireless device location determination
US20090189810A1 (en) 2008-01-24 2009-07-30 Broadcom Corporation Weighted aiding for positioning systems
WO2009099773A2 (en) 2008-02-01 2009-08-13 Walker Jonathan B Systems and methods for providing location based services (lbs) utilizing wlan and/or gps signals for seamless indoor and outdoor tracking
US8018950B2 (en) * 2008-03-17 2011-09-13 Wi-Lan, Inc. Systems and methods for distributing GPS clock to communications devices
US7602334B1 (en) 2008-04-03 2009-10-13 Beceem Communications Inc. Method and system of a mobile subscriber estimating position
WO2010005731A1 (en) 2008-06-16 2010-01-14 Skyhook Wireless, Inc. Methods and systems for determining location using a cellular and wlan positioning system by selecting the best wlan ps solution
US9155017B2 (en) 2009-02-03 2015-10-06 Kyocera Corporation Access point detection for wireless networking
WO2011008613A1 (en) 2009-07-16 2011-01-20 Skyhook Wireless, Inc. Systems and methods for using a hybrid satellite and wlan positioning system
WO2011041430A1 (en) 2009-10-02 2011-04-07 Skyhook Wireless, Inc. Determining position in a hybrid positioning system using a dilution of precision metric
US8619643B2 (en) 2010-03-24 2013-12-31 Skyhook Wireless, Inc. System and method for estimating the probability of movement of access points in a WLAN-based positioning system
US8559974B2 (en) 2010-06-11 2013-10-15 Skyhook Wireless, Inc. Methods of and systems for measuring beacon stability of wireless access points

Patent Citations (99)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5420592A (en) * 1993-04-05 1995-05-30 Radix Technologies, Inc. Separated GPS sensor and processing system for remote GPS sensing and centralized ground station processing for remote mobile position and velocity determinations
US6185427B1 (en) * 1996-09-06 2001-02-06 Snaptrack, Inc. Distributed satellite position system processing and application network
US6262741B1 (en) * 1998-03-17 2001-07-17 Prc Public Sector, Inc. Tiling of object-based geographic information system (GIS)
US6678611B2 (en) * 1998-03-25 2004-01-13 Navigation Technologies Corp. Method and system for route calculation in a navigation application
US20040039520A1 (en) * 1998-03-25 2004-02-26 Asta Khavakh Method and system for route calculation in a navigation application
US6707422B2 (en) * 1998-07-02 2004-03-16 Snaptrack Incorporated Method and apparatus for measurement processing of satellite positioning system (SPS) signals
US6725158B1 (en) * 1999-07-12 2004-04-20 Skybitz, Inc. System and method for fast acquisition reporting using communication satellite range measurement
US6741188B1 (en) * 1999-10-22 2004-05-25 John M. Miller System for dynamically pushing information to a user utilizing global positioning system
US20030011511A1 (en) * 1999-11-12 2003-01-16 King Thomas M. Method and apparatus for assisted GPS
US6587692B1 (en) * 2000-03-30 2003-07-01 Lucent Technologies Inc. Location determination using weighted ridge regression
US20020055956A1 (en) * 2000-09-08 2002-05-09 Krasnoiarov Boris Andreyevich Method and system for assembling concurrently-generated content
US6420999B1 (en) * 2000-10-26 2002-07-16 Qualcomm, Inc. Method and apparatus for determining an error estimate in a hybrid position determination system
US6574557B2 (en) * 2001-04-27 2003-06-03 Pioneer Corporation Positioning error range setting apparatus, method, and navigation apparatus
US20030043073A1 (en) * 2001-09-05 2003-03-06 Gray Matthew K. Position detection and location tracking in a wireless network
US6888811B2 (en) * 2001-09-24 2005-05-03 Motorola, Inc. Communication system for location sensitive information and method therefor
US20030125045A1 (en) * 2001-12-27 2003-07-03 Riley Wyatt Thomas Creating and using base station almanac information in a wireless communication system having a position location capability
US7167716B2 (en) * 2002-02-08 2007-01-23 Curitel Communications, Inc. Synchronous demodulation apparatus of base transceiver station in interim standard-2000 system
US7167715B2 (en) * 2002-05-17 2007-01-23 Meshnetworks, Inc. System and method for determining relative positioning in AD-HOC networks
US20040019679A1 (en) * 2002-07-24 2004-01-29 Sandhya E First thread lock management for distributed data systems
US20040023669A1 (en) * 2002-07-31 2004-02-05 Interdigital Technology Corporation Handover between a cellular system and a wireless local area network
US20040081133A1 (en) * 2002-10-25 2004-04-29 Nattavut Smavatkul Method of communication device initiated frame exchange
US20040087317A1 (en) * 2002-10-30 2004-05-06 Lockheed Martin Corporation Cooperative element location system
US20050020266A1 (en) * 2003-02-24 2005-01-27 Floyd Backes Distance determination apparatus for use by devices in a wireless network
US20060078122A1 (en) * 2003-03-25 2006-04-13 Dacosta Behram M Location-based wireless messaging for wireless devices
US20050017898A1 (en) * 2003-06-03 2005-01-27 Koichiro Teranishi Positional information determining apparatus
US20050037775A1 (en) * 2003-06-27 2005-02-17 Mark Moeglein Method and apparatus for wireless network hybrid positioning
US20050090266A1 (en) * 2003-06-27 2005-04-28 Leonid Sheynblat Local area network assisted positioning
US7250907B2 (en) * 2003-06-30 2007-07-31 Microsoft Corporation System and methods for determining the location dynamics of a portable computing device
US20060089160A1 (en) * 2003-08-11 2006-04-27 Core Mobility, Inc. Systems and methods for displaying location-based maps on communication devices
US7221928B2 (en) * 2003-10-01 2007-05-22 Laird Mark D Mobile emergency notification system
US6894645B1 (en) * 2003-12-11 2005-05-17 Nokia Corporation Position estimation
US7545894B2 (en) * 2004-03-19 2009-06-09 Purdue Research Foundation Method and apparatus for detecting and processing global positioning system (GPS) signals
US20060040640A1 (en) * 2004-04-05 2006-02-23 Demetrius Thompson Cellular telephone safety system
US20060009235A1 (en) * 2004-06-18 2006-01-12 Leonid Sheynblat Method and apparatus for determining location of a base station using a plurality of mobile stations in a wireless mobile network
US20060046709A1 (en) * 2004-06-29 2006-03-02 Microsoft Corporation Proximity detection using wireless signal strengths
US20060089157A1 (en) * 2004-10-27 2006-04-27 Qwest Communications International Inc. Mobile caching and data relay vectoring systems and methods
US20110035420A1 (en) * 2004-10-29 2011-02-10 Farshid Alizadeh-Shabdiz Location Beacon Database
US20080132170A1 (en) * 2004-10-29 2008-06-05 Skyhook Wireless, Inc. Location-based services that choose location algorithms based on number of detected access points within range of user device
US20080139217A1 (en) * 2004-10-29 2008-06-12 Skyhook Wireless, Inc. Location-based services that choose location algorithms based on number of detected wireless signal stations within range of user device
US20060095348A1 (en) * 2004-10-29 2006-05-04 Skyhook Wireless, Inc. Server for updating location beacon database
US20090075672A1 (en) * 2004-10-29 2009-03-19 Skyhook Wireless, Inc. Server for updating location beacon database
US20060106850A1 (en) * 2004-10-29 2006-05-18 Skyhook Wireless, Inc. Location beacon database
US20060095349A1 (en) * 2004-10-29 2006-05-04 Skyhook Wireless, Inc. Method and system for building a location beacon database
US7403762B2 (en) * 2004-10-29 2008-07-22 Skyhook Wireless, Inc. Method and system for building a location beacon database
US7236126B2 (en) * 2004-12-13 2007-06-26 Samsung Electronics Co., Ltd. AGPS system using NTP server and method for determining the location of a terminal using a NTP server
US7397424B2 (en) * 2005-02-03 2008-07-08 Mexens Intellectual Property Holding, Llc System and method for enabling continuous geographic location estimation for wireless computing devices
US20070126635A1 (en) * 2005-02-03 2007-06-07 Cyril Houri System and Method for Determining Geographic Location of Wireless Computing Devices
US20070004428A1 (en) * 2005-02-22 2007-01-04 Skyhook Wireless, Inc. Continuous data optimization of moved access points in positioning systems
US7474897B2 (en) * 2005-02-22 2009-01-06 Skyhook Wireless, Inc. Continuous data optimization by filtering and positioning systems
US7493127B2 (en) * 2005-02-22 2009-02-17 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US20090149197A1 (en) * 2005-02-22 2009-06-11 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US20070004427A1 (en) * 2005-02-22 2007-01-04 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US7502620B2 (en) * 2005-03-04 2009-03-10 Shyhook Wireless, Inc. Encoding and compression of a location beacon database
US20070052583A1 (en) * 2005-09-08 2007-03-08 Topcon Gps, Llc Position determination using carrier phase measurements of satellite signals
US20080176583A1 (en) * 2005-10-28 2008-07-24 Skyhook Wireless, Inc. Method and system for selecting and providing a relevant subset of wi-fi location information to a mobile client device so the client device may estimate its position with efficient utilization of resources
US20070097511A1 (en) * 2005-10-28 2007-05-03 Cymer, Inc. Systems and methods for generating laser light shaped as a line beam
US20070100955A1 (en) * 2005-10-29 2007-05-03 Bodner Oran J System and method for using known geographic locations of Internet users to present local content to web pages
US20070121560A1 (en) * 2005-11-07 2007-05-31 Edge Stephen W Positioning for wlans and other wireless networks
US20070109184A1 (en) * 2005-11-15 2007-05-17 Shyr You-Yuh J Novas hybrid positioning technology using terrestrial digital broadcasting signal (DBS) and global positioning system (GPS) satellite signal
US20070150516A1 (en) * 2005-11-23 2007-06-28 Morgan Edward J Location toolbar for internet search and communication
US7664511B2 (en) * 2005-12-12 2010-02-16 Nokia Corporation Mobile location method for WLAN-type systems
US20070167174A1 (en) * 2006-01-19 2007-07-19 Halcrow Michael A On-device mapping of WIFI hotspots via direct connection of WIFI-enabled and GPS-enabled mobile devices
US7551929B2 (en) * 2006-05-08 2009-06-23 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations
US20090154371A1 (en) * 2006-05-08 2009-06-18 Skyhook Wireless, Inc. Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system
US7551579B2 (en) * 2006-05-08 2009-06-23 Skyhook Wireless, Inc. Calculation of quality of wlan access point characterization for use in a wlan positioning system
US7515578B2 (en) * 2006-05-08 2009-04-07 Skyhook Wireless, Inc. Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system
US20090175189A1 (en) * 2006-05-08 2009-07-09 Skyhook Wireless, Inc. Calculation of quality of wlan access point characterization for use in a wlan positioning system
US20110058495A1 (en) * 2006-05-08 2011-03-10 Skyhook Wireless, Inc. Estimation of Speed and Direction of Travel in a WLAN Positioning System
US7916661B2 (en) * 2006-05-08 2011-03-29 Skyhook Wireless, Inc. Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system
US20080133336A1 (en) * 2006-06-01 2008-06-05 Altman Samuel H Location-Based Advertising Message Serving For Mobile Communication Devices
US20080004888A1 (en) * 2006-06-29 2008-01-03 Microsoft Corporation Wireless, location-based e-commerce for mobile communication devices
US20080008120A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of improving sampling of wlan packet information to improve estimates of doppler frequency of a wlan positioning device
US20080008118A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of gathering wlan packet samples to improve position estimates of wlan positioning device
US20080008119A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of gathering and caching wlan packet information to improve position estimates of a wlan positioning device
US20080008117A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. Method and system for employing a dedicated device for position estimation by a wlan positioning system
US20080008121A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of passive and active scanning of wlan-enabled access points to estimate position of a wlan positioning device
US20080032706A1 (en) * 2006-08-01 2008-02-07 Leonid Sheynblat System And/Or Method For Providing Information Updates To A Location Server
US20080033646A1 (en) * 2006-08-04 2008-02-07 Morgan Edward J Systems and Methods of Automated Retrieval of Location Information from a User Device for use with Server Systems
US20080079633A1 (en) * 2006-08-23 2008-04-03 Qualcomm Incorporated System and/or method for reducing ambiguities in received sps signals
US20110080841A1 (en) * 2006-11-07 2011-04-07 Skyhook Wireless, Inc. System and Method for Estimating Positioning Error within a WLAN-Based Positioning System
US20080108371A1 (en) * 2006-11-07 2008-05-08 Farshid Alizadeh-Shabdiz System and method for estimating positioning error within a wlan-based positioning system
US20080111737A1 (en) * 2006-11-15 2008-05-15 Motorola Inc. Method and system for hybrid location aiding for multi-mode devices
US20080158053A1 (en) * 2006-12-05 2008-07-03 Alpine Electronics, Inc. GPS Position Measuring Device
US20090042557A1 (en) * 2007-02-05 2009-02-12 Wefi, Inc. System and Method For Mapping Wireless Access Points
US7724612B2 (en) * 2007-04-20 2010-05-25 Sirf Technology, Inc. System and method for providing aiding information to a satellite positioning system receiver over short-range wireless connections
US20090002237A1 (en) * 2007-06-27 2009-01-01 Motorola, Inc. Method and device for determining a position of a portable electronic device
US20090168843A1 (en) * 2007-10-03 2009-07-02 Texas Instruments Incorporated Power-saving receiver circuits, systems and processes
US20090121927A1 (en) * 2007-11-14 2009-05-14 Radiofy Llc Systems and Methods of Assisted GPS
US20090161806A1 (en) * 2007-12-19 2009-06-25 Apple Inc. Microcontroller clock calibration using data transmission from an accurate third party
US20090181695A1 (en) * 2008-01-14 2009-07-16 Nokia Corporation Use of movement information about a wireless client
US20100052983A1 (en) * 2008-06-06 2010-03-04 Skyhook Wireless, Inc. Systems and methods for maintaining clock bias accuracy in a hybrid positioning system
US20100039323A1 (en) * 2008-08-12 2010-02-18 Andrei Kosolobov Method and system for global position reference map (gprm) for agps
US20110012784A1 (en) * 2009-07-16 2011-01-20 Skyhook Wireless, Inc. Methods and systems for determining location using a hybrid satellite and wlan positioning system by selecting the best sps measurements
US20110012780A1 (en) * 2009-07-16 2011-01-20 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved wlan access points
US20110021207A1 (en) * 2009-07-24 2011-01-27 Morgan Edward J System and Method for Estimating Positioning Error Within a WLAN-Based Positioning System
US20110045840A1 (en) * 2009-08-18 2011-02-24 Skyhook Wireless, Inc. Method and system for estimating range of mobile device to wireless installation
US20110074626A1 (en) * 2009-09-29 2011-03-31 Skyhook Wireless, Inc. Improvement of the accuracy and performance of a hybrid positioning system
US20110080317A1 (en) * 2009-10-02 2011-04-07 Skyhook Wireless, Inc. Method of determining position in a hybrid positioning system using a dilution of precision metric
US20110080318A1 (en) * 2009-10-02 2011-04-07 Skyhook Wireless, Inc. Determining A Dilution of Precision Metric Using Two or Three GPS Satellites

Cited By (103)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10080208B2 (en) 2004-10-29 2018-09-18 Skyhook Wireless, Inc. Techniques for setting quality attributes of access points in a positioning system
US8478297B2 (en) 2004-10-29 2013-07-02 Skyhook Wireless, Inc. Continuous data optimization of moved access points in positioning systems
US8538457B2 (en) 2004-10-29 2013-09-17 Skyhook Wireless, Inc. Continuous data optimization of moved access points in positioning systems
US8983493B2 (en) 2004-10-29 2015-03-17 Skyhook Wireless, Inc. Method and system for selecting and providing a relevant subset of Wi-Fi location information to a mobile client device so the client device may estimate its position with efficient utilization of resources
US8031657B2 (en) 2004-10-29 2011-10-04 Skyhook Wireless, Inc. Server for updating location beacon database
US9398558B2 (en) 2004-10-29 2016-07-19 Skyhook Wireless, Inc. Continuous data optimization of moved access points in positioning systems
US7818017B2 (en) 2004-10-29 2010-10-19 Skyhook Wireless, Inc. Location-based services that choose location algorithms based on number of detected wireless signal stations within range of user device
US7769396B2 (en) 2004-10-29 2010-08-03 Skyhook Wireless, Inc. Location-based services that choose location algorithms based on number of detected access points within range of user device
US8140094B2 (en) 2005-02-22 2012-03-20 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US8244272B2 (en) 2005-02-22 2012-08-14 Skyhook Wireless, Inc. Continuous data optimization of moved access points in positioning systems
US9037162B2 (en) 2005-02-22 2015-05-19 Skyhook Wireless, Inc. Continuous data optimization of new access points in positioning systems
US20080192696A1 (en) * 2005-07-25 2008-08-14 Joachim Sachs Handover Optimisation in a Wlan Radio Access Network
US8369264B2 (en) 2005-10-28 2013-02-05 Skyhook Wireless, Inc. Method and system for selecting and providing a relevant subset of Wi-Fi location information to a mobile client device so the client device may estimate its position with efficient utilization of resources
US9363785B2 (en) 2006-05-08 2016-06-07 Skyhook Wireless, Inc. Calculation of quality of WLAN access point characterization for use in a WLAN positioning system
US8155673B2 (en) 2006-05-08 2012-04-10 Skyhook Wireless, Inc. Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system
US20090154371A1 (en) * 2006-05-08 2009-06-18 Skyhook Wireless, Inc. Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system
US9955358B2 (en) 2006-05-08 2018-04-24 Skyhook Wireless, Inc. Determining quality metrics utilized in building a reference database
US20110058495A1 (en) * 2006-05-08 2011-03-10 Skyhook Wireless, Inc. Estimation of Speed and Direction of Travel in a WLAN Positioning System
US7916661B2 (en) 2006-05-08 2011-03-29 Skyhook Wireless, Inc. Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system
US8526967B2 (en) 2006-05-08 2013-09-03 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system
US20110164522A1 (en) * 2006-05-08 2011-07-07 Skyhook Wireless, Inc. Estimation of Position Using WLAN Access Point Radio Propagation Characteristics in a WLAN Positioning System
US7835754B2 (en) 2006-05-08 2010-11-16 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system
US8014788B2 (en) 2006-05-08 2011-09-06 Skyhook Wireless, Inc. Estimation of speed of travel using the dynamic signal strength variation of multiple WLAN access points
US9008690B2 (en) 2006-05-08 2015-04-14 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system
US8103288B2 (en) 2006-05-08 2012-01-24 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations
US8090386B2 (en) 2006-05-08 2012-01-03 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system
US20070258420A1 (en) * 2006-05-08 2007-11-08 Farshid Alizadeh-Shabdiz Estimation of speed of travel using the dynamic signal strength variation of multiple WLAN access points
US9052378B2 (en) 2006-05-08 2015-06-09 Skyhook Wireless, Inc. Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system
US8706140B2 (en) 2006-07-07 2014-04-22 Skyhook Wireless, Inc. System and method of passive and active scanning of WLAN-enabled access points to estimate position of a WLAN positioning device
US20080008121A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of passive and active scanning of wlan-enabled access points to estimate position of a wlan positioning device
US7768963B2 (en) 2006-07-07 2010-08-03 Skyhook Wireless, Inc. System and method of improving sampling of WLAN packet information to improve estimates of Doppler frequency of a WLAN positioning device
US8229455B2 (en) 2006-07-07 2012-07-24 Skyhook Wireless, Inc. System and method of gathering and caching WLAN packet information to improve position estimates of a WLAN positioning device
US20080008120A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of improving sampling of wlan packet information to improve estimates of doppler frequency of a wlan positioning device
US8315233B2 (en) 2006-07-07 2012-11-20 Skyhook Wireless, Inc. System and method of gathering WLAN packet samples to improve position estimates of WLAN positioning device
US20080008118A1 (en) * 2006-07-07 2008-01-10 Skyhook Wireless, Inc. System and method of gathering wlan packet samples to improve position estimates of wlan positioning device
US8144673B2 (en) 2006-07-07 2012-03-27 Skyhook Wireless, Inc. Method and system for employing a dedicated device for position estimation by a WLAN positioning system
US8185129B2 (en) 2006-07-07 2012-05-22 Skyhook Wireless, Inc. System and method of passive and active scanning of WLAN-enabled access points to estimate position of a WLAN positioning device
US8019357B2 (en) 2006-11-07 2011-09-13 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
US9426613B2 (en) 2006-11-07 2016-08-23 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
US8909245B2 (en) 2006-11-07 2014-12-09 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
US10284997B2 (en) 2006-11-07 2019-05-07 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
US20110080841A1 (en) * 2006-11-07 2011-04-07 Skyhook Wireless, Inc. System and Method for Estimating Positioning Error within a WLAN-Based Positioning System
US20080108371A1 (en) * 2006-11-07 2008-05-08 Farshid Alizadeh-Shabdiz System and method for estimating positioning error within a wlan-based positioning system
US7856234B2 (en) 2006-11-07 2010-12-21 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
US20080248808A1 (en) * 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Estimation of position, speed and bearing using time difference of arrival and received signal strength in a wlan positioning system
US20080248741A1 (en) * 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Time difference of arrival based estimation of direction of travel in a wlan positioning system
US8054219B2 (en) 2008-06-06 2011-11-08 Skyhook Wireless, Inc. Systems and methods for determining position using a WLAN-PS estimated position as an initial position in a hybrid positioning system
US20090303112A1 (en) * 2008-06-06 2009-12-10 Skyhook Wireless, Inc. System and method for refining a wlan-ps estimated location using satellite measurements in a hybrid positioning system
US8089399B2 (en) 2008-06-06 2012-01-03 Skyhook Wireless, Inc. System and method for refining a WLAN-PS estimated location using satellite measurements in a hybrid positioning system
US8089398B2 (en) 2008-06-06 2012-01-03 Skyhook Wireless, Inc. Methods and systems for stationary user detection in a hybrid positioning system
US8130148B2 (en) 2008-06-06 2012-03-06 Skyhook Wireless, Inc. System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system
US7999742B2 (en) 2008-06-06 2011-08-16 Skyhook Wireless, Inc. System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system
US8462745B2 (en) 2008-06-16 2013-06-11 Skyhook Wireless, Inc. Methods and systems for determining location using a cellular and WLAN positioning system by selecting the best WLAN PS solution
US8155666B2 (en) 2008-06-16 2012-04-10 Skyhook Wireless, Inc. Methods and systems for determining location using a cellular and WLAN positioning system by selecting the best cellular positioning system solution
US8638725B2 (en) 2008-06-16 2014-01-28 Skyhook Wireless, Inc. Methods and systems for determining location using a cellular and WLAN positioning system by selecting the best WLAN PS solution
US20090312036A1 (en) * 2008-06-16 2009-12-17 Skyhook Wireless, Inc. Methods and systems for improving the accuracy of expected error estimation in location determinations using a hybrid cellular and wlan positioning system
US8154454B2 (en) 2009-07-16 2012-04-10 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US8564481B2 (en) 2009-07-16 2013-10-22 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US8223074B2 (en) 2009-07-16 2012-07-17 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US9013350B2 (en) 2009-07-16 2015-04-21 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US8284103B2 (en) 2009-07-16 2012-10-09 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US10031237B2 (en) 2009-07-16 2018-07-24 Skyhook Wireless, Inc. Techniques for selecting SPS measurements to use in determining a final location estimate based on a WLAN-based location estimate
US8063820B2 (en) 2009-07-16 2011-11-22 Skyhook Wireless, Inc. Methods and systems for determining location using a hybrid satellite and WLAN positioning system by selecting the best SPS measurements
US8022877B2 (en) 2009-07-16 2011-09-20 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US8242960B2 (en) 2009-07-16 2012-08-14 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US20110021207A1 (en) * 2009-07-24 2011-01-27 Morgan Edward J System and Method for Estimating Positioning Error Within a WLAN-Based Positioning System
US8406785B2 (en) 2009-08-18 2013-03-26 Skyhook Wireless, Inc. Method and system for estimating range of mobile device to wireless installation
US9237415B2 (en) 2009-08-18 2016-01-12 Skyhook Wireless, Inc. Method and system for estimating range of mobile device to wireless installation
US8638256B2 (en) 2009-09-29 2014-01-28 Skyhook Wireless, Inc. Accuracy and performance of a hybrid positioning system
US8279114B2 (en) 2009-10-02 2012-10-02 Skyhook Wireless, Inc. Method of determining position in a hybrid positioning system using a dilution of precision metric
US20130005356A1 (en) * 2010-01-07 2013-01-03 Nec Corporation Radio communication system, radio terminal, radio network, radio communication method and program
US9544868B2 (en) * 2010-01-07 2017-01-10 Nec Corporation Radio communication system, radio terminal, radio network, radio communication method and program
US8433334B2 (en) 2010-01-15 2013-04-30 Apple Inc. Managing a location database for network-based positioning system
US8660576B2 (en) 2010-01-15 2014-02-25 Apple Inc. Adaptive location determination
US8504059B2 (en) 2010-01-15 2013-08-06 Apple Inc. Location filtering using mobile country code
US8200251B2 (en) 2010-01-15 2012-06-12 Apple Inc. Determining a location of a mobile device using a location database
US8634860B2 (en) 2010-01-15 2014-01-21 Apple Inc. Location determination using cached location area codes
US9119168B2 (en) 2010-01-15 2015-08-25 Apple Inc. Managing a location database for network-based positioning system
US8655371B2 (en) 2010-01-15 2014-02-18 Apple Inc. Location determination using cached location area codes
US8619643B2 (en) 2010-03-24 2013-12-31 Skyhook Wireless, Inc. System and method for estimating the probability of movement of access points in a WLAN-based positioning system
US9253605B2 (en) 2010-03-24 2016-02-02 Skyhook Wireless, Inc. System and method for resolving multiple location estimate conflicts in a WLAN-positioning system
US9516471B2 (en) 2010-03-24 2016-12-06 Skyhook Wireless, Inc. System and method for estimating the probability of movement of access points in a WLAN-based positioning system
US8620344B2 (en) 2010-04-07 2013-12-31 Apple Inc. Location-based application program management
US9210529B2 (en) 2010-04-07 2015-12-08 Apple Inc. Location-based application program management
US9008061B2 (en) 2010-05-26 2015-04-14 Ntt Docomo, Inc. Positioning device and positioning method
US8971915B2 (en) 2010-06-11 2015-03-03 Skyhook Wireless, Inc. Systems for and methods of determining likelihood of mobility of reference points in a positioning system
US9521512B2 (en) 2010-06-11 2016-12-13 Skyhook Wireless, Inc. Determining a designated wireless device lacks a fixed geographic location and using the determination to improve location estimates
US8559974B2 (en) 2010-06-11 2013-10-15 Skyhook Wireless, Inc. Methods of and systems for measuring beacon stability of wireless access points
US8630657B2 (en) 2010-06-11 2014-01-14 Skyhook Wireless, Inc. Systems for and methods of determining likelihood of reference point identity duplication in a positioning system
US8700053B2 (en) 2010-06-11 2014-04-15 Skyhook Wireless, Inc. Systems for and methods of determining likelihood of relocation of reference points in a positioning system
US8971923B2 (en) 2010-06-11 2015-03-03 Skyhook Wireless, Inc. Methods of and systems for measuring beacon stability of wireless access points
US9014715B2 (en) 2010-06-11 2015-04-21 Skyhook Wireless, Inc. Systems for and methods of determining likelihood of atypical transmission characteristics of reference points in a positioning system
US20120072110A1 (en) * 2010-09-17 2012-03-22 Atheros Communications, Inc. Indoor positioning using pressure sensors
US9234965B2 (en) * 2010-09-17 2016-01-12 Qualcomm Incorporated Indoor positioning using pressure sensors
US9467807B2 (en) 2010-10-05 2016-10-11 Skyhook Wireless, Inc. Estimating demographics associated with a selected geographic area
US9031580B2 (en) 2010-10-05 2015-05-12 Skyhook Wireless, Inc. Method of and system for estimating temporal demographics of mobile users
US8606294B2 (en) 2010-10-05 2013-12-10 Skyhook Wireless, Inc. Method of and system for estimating temporal demographics of mobile users
US8890746B2 (en) 2010-11-03 2014-11-18 Skyhook Wireless, Inc. Method of and system for increasing the reliability and accuracy of location estimation in a hybrid positioning system
US9298897B2 (en) 2011-06-22 2016-03-29 Skyhook Wireless, Inc. Method of and systems for privacy preserving mobile demographic measurement of individuals, groups and locations over time and space
US10304086B2 (en) 2011-06-22 2019-05-28 Skyhook Wireless, Inc. Techniques for estimating demographic information
US9730079B2 (en) 2012-04-16 2017-08-08 Zte Corporation Joint positioning method and device
CN105988128A (en) * 2015-03-20 2016-10-05 福特全球技术公司 Vehicle location accuracy
US9635510B1 (en) 2016-06-24 2017-04-25 Athentek Innovations, Inc. Database for Wi-Fi position estimation

Also Published As

Publication number Publication date
US8054219B2 (en) 2011-11-08
WO2009149417A1 (en) 2009-12-10
AU2009255955A1 (en) 2009-12-10
US8089398B2 (en) 2012-01-03
CN102100058A (en) 2011-06-15
KR20110016473A (en) 2011-02-17
US7999742B2 (en) 2011-08-16
JP2011523062A (en) 2011-08-04
US20110298659A1 (en) 2011-12-08
US20100052983A1 (en) 2010-03-04
US8130148B2 (en) 2012-03-06
CA2727038A1 (en) 2009-12-10
JP5775449B2 (en) 2015-09-09
US20090303120A1 (en) 2009-12-10
US20090303119A1 (en) 2009-12-10
US8089399B2 (en) 2012-01-03
US20090303121A1 (en) 2009-12-10
US20090303112A1 (en) 2009-12-10
KR101603810B1 (en) 2016-03-16
US20090303115A1 (en) 2009-12-10
EP2283641B1 (en) 2020-08-12
US20090303114A1 (en) 2009-12-10
EP2283641A1 (en) 2011-02-16
EP2283641A4 (en) 2012-12-19

Similar Documents

Publication Publication Date Title
US7999742B2 (en) System and method for using a satellite positioning system to filter WLAN access points in a hybrid positioning system
US10031237B2 (en) Techniques for selecting SPS measurements to use in determining a final location estimate based on a WLAN-based location estimate
US8063820B2 (en) Methods and systems for determining location using a hybrid satellite and WLAN positioning system by selecting the best SPS measurements
US20090312036A1 (en) Methods and systems for improving the accuracy of expected error estimation in location determinations using a hybrid cellular and wlan positioning system
WO2011008613A1 (en) Systems and methods for using a hybrid satellite and wlan positioning system
AU2009255955B2 (en) Method and system for determining location using a hybrid satellite and WLAN positioning system by selecting the best WLAN-PS solution
AU2012200417B2 (en) Method and system for determining location using a hybrid satellite and WLAN positioning system by selecting the best WLAN-PS solution

Legal Events

Date Code Title Description
AS Assignment

Owner name: SKYHOOK WIRELESS, INC., MASSACHUSETTS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ALIZADEH-SHABDIZ, FARSHID;REEL/FRAME:023495/0472

Effective date: 20091020

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION