CA2651853C - Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system - Google Patents
Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system Download PDFInfo
- Publication number
- CA2651853C CA2651853C CA2651853A CA2651853A CA2651853C CA 2651853 C CA2651853 C CA 2651853C CA 2651853 A CA2651853 A CA 2651853A CA 2651853 A CA2651853 A CA 2651853A CA 2651853 C CA2651853 C CA 2651853C
- Authority
- CA
- Canada
- Prior art keywords
- access point
- access points
- power
- coverage
- distance
- 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.)
- Active
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO 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
- G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
- G01S11/02—Systems for determining distance or velocity not using reflection or reradiation using radio waves
- G01S11/06—Systems for determining distance or velocity not using reflection or reradiation using radio waves using intensity measurements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO 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
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/02—Position-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
- G01S5/0252—Radio frequency fingerprinting
- G01S5/02521—Radio frequency fingerprinting using a radio-map
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/18—Network planning tools
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/10—Small scale networks; Flat hierarchical networks
- H04W84/12—WLAN [Wireless Local Area Networks]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
Abstract
A method for estimating position using WLAN access point radio propagation characteristics in a WLAN location based service is provided. A location-based services system has a plurality of Wi-Fi access points in a target area. The Wi-Fi access points are positioned at geographic locations and have signal coverage areas. A method of characterizing at least one of the Wi-Fi access points comprises determining the geographic location of the Wi-Fi access point, dividing the signal coverage area of the Wi-Fi access point into at least one section, and determining radio propagation characteristics for each section. The radio propagation characteristics of each section characterize a radio channel of the Wi-Fi access point, and the characterization can be used in a location algorithm.
Description
ESTIMATION OF POSITION USING WLAN ACCESS POINT RADIO
= PROPAGATION CHARACTERISTICS IN A WLAN POSITIONING
SYSTEM
Background Field of the Invention [0001] The invention generally relates to positioning systems and, more specifically, to methods and systems of estimating attributes of user movement (e.g., position, speed, and direction) using WLAN access point radio propagation characteristics in a WLAN positioning system.
Discussion of Related Art
= PROPAGATION CHARACTERISTICS IN A WLAN POSITIONING
SYSTEM
Background Field of the Invention [0001] The invention generally relates to positioning systems and, more specifically, to methods and systems of estimating attributes of user movement (e.g., position, speed, and direction) using WLAN access point radio propagation characteristics in a WLAN positioning system.
Discussion of Related Art
[0002] Position deteimination is the main component of navigation systems and any Location Based Services (LBS). Proliferation of WLAN access points in recent years created a blanket of WLAN radio waves everywhere. Therefore, almost in any place, there is a great possibility of detecting WLAN radio waves, especially in urban areas. The exponential growth of WLAN, and the fact that they can be found almost everywhere, initiated an idea of leveraging them for a metropolitan positioning system for indoor and outdoor areas. In a metropolitan WLAN positioning system, location of WLAN access points are used as reference points, and the Received Signal Strength (RSS) of a WLAN access point is used as an indicator of a distance of an end user from the WLAN access points that the user detects at any time. By knowing the distance of the end user from WLAN
access points, location of the end user can be determined. Translating receiver Receive Signal Strength to distance relies on assuming a specific radio channel model. Ideally, if the radio channel model was exactly known, the exact distance of the end user to WLAN access points could be found.
access points, location of the end user can be determined. Translating receiver Receive Signal Strength to distance relies on assuming a specific radio channel model. Ideally, if the radio channel model was exactly known, the exact distance of the end user to WLAN access points could be found.
[0003] Outdoor and indoor WLAN based positioning systems have been explored by couple of research labs, but none of them included speed and bearing estimation in their system. The most important research efforts in this area have been conducted by PlaceLab (www.placelab.com, a project sponsored by Microsoft and Intel), 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, and it was evaluated through several small projects at Dartmouth college (e.g., M. Kim, J.J. Fielding, and D. Kotz, "Risks of using AP locations discovered through war driving").
[00041 There have been a number of commercial offerings of Wi-Fi location systems targeted at indoor positioning. (See, e.g., Kavitha Muthukrishnan, Maria Lijding, Paul Havinga, Towards Smart Surroundings: Enabling Techniques and Technologies for Localization, Proceedings of the International Workshop on Location and Context-Awareness (LoCA 2005) at Pervasive 2005, May 2005, and Hazas, M., Scott, J., Krumm, J.: Location-Aware Computing Comes of Age.
IEEE Computer, 37(2):95-97, Feb 2004 005, Pa005, Pages 350-362.) These systems are designed to address asset and people tracking within a controlled environment like a corporate campus, a hospital facility or a shipping yard.
The classic example is having a system that can monitor the exact location of the crash cart within the hospital so that when there is a cardiac arrest the hospital staff doesn't waste time locating the device. The accuracy requirements for these use cases are very demanding typically calling for 1-3 meter accuracy.
[00051 These systems use a variety of techniques to fine tune their accuracy including conducting detailed site surveys of every square foot of the campus to measure radio signal propagation. They also require a constant network connection so that the access point and the client radio can exchange synchronization information similar to how A-GPS works. While these systems are becoming more reliable for indoor use cases, they are ineffective in any wide-area deployment. It is impossible to conduct the kind of detailed site survey required across an entire city and there is no way to rely on a constant communication channel with 802.11 access points across an entire metropolitan area to the extent required by these systems. Most importantly outdoor radio propagation is fundamentally different than indoor radio propagation rendering these indoor positioning algorithms almost useless in a wide-area scenario.
The required accuracy of indoor WLAN based positioning systems, makes it hard to use radio channel modeling and it is considered as a research topic in that domain.
In addition, none of the WLAN based positioning systems to date have distinguished between access points, and current methods treat all WLAN access points the same.
[0006] Figure 1 depicts a Wi-Fi positioning system (WPS). The positioning system includes positioning software [103] that resides on a computing device [101]. Throughout a particular coverage area there are fixed wireless access points [102] that broadcast information using control/common channel broadcast signals. The client device monitors the broadcast signal or requests its transmission via a probe request. Each access point contains a unique hardware identifier known as a MAC address. The client positioning software receives signal beacons from the 802.11 access points in range and calculates the geographic location of the computing device using characteristics from the signal beacons. Those characteristics include the unique identifier of the 802.11 access point, known as the MAC address, and the strengths of the signal reaching the client device. The client software compares the observed 802.11 access points with those in its reference database [104] of access points, which may or may not reside on the device as well. The reference database contains the calculated geographic locations and power profile of all the access points the gathering system has collected. The power profile may be generated from a collection of readings that represent the power of the signal from various locations. Using these known locations, the client software calculates the relative position of the user device [101] and determines its geographic coordinates in the form of latitude and longitude readings. Those readings are then fed to location-based applications such as friend finders, local search web sites, fleet management systems and E911 services.
Summary [0007] The invention provides methods and systems for estimating position using WLAN (e.g., Wi-Fi) access point radio propagation characteristics in a WLAN location based service.
[0008] Aspects of the invention classifying WLAN access points based on a radio channel model can use any channel model, and the invention is independent of any specific channel model.
[0009] Under one aspect of the invention, a location-based services system has a plurality of Wi-Fi access points in a target area. The Wi-Fi access points are positioned at geographic locations and have signal coverage areas. A
method of characterizing at least one of the Wi-Fi access points comprises determining the geographic location of the Wi-Fi access point, dividing the signal coverage area of the Wi-Fi access point into at least one section, and detei mining radio propagation characteristics for each section. The radio propagation characteristics of each section characterize a radio channel of the Wi-Fi access point, and the characterization can be used in a location algorithm.
[0010] Under another aspect of the invention, the signal coverage area is characterized as one section.
[0011] Under another aspect of the invention, the signal coverage is divided into more than one section. Under certain embodiments, radials emanating outward from the Wi-Fi access point form the sections. Under further embodiments, sections are formed based on a distance from the Wi-Fi access point. Under yet further embodiments, sections are formed based on both radials and distances from the Wi-Fi access point.
[0012] Under another aspect of the invention, a plurality of received signal power values within the signal coverage area is measured. Each received signal power value is measured at an associated position relative to the Wi-Fi access point. The sections are determined based on the plurality of received signal power values and associated positions.
[0013] Under another aspect of the invention, the radio propagation characteristics include a signal power-distance gradient.
[0014] Under another aspect of the invention, the signal power-distance gradient for each section is determined by measuring a plurality of received signal power values within the signal coverage area, each received signal power value being measured at an associated position relative to the Wi-Fi access point, performing a linear regression on the plurality of received signal power values and associated positions, and using a slope determined by the linear regression to calculate the signal power-distance gradient.
[00041 There have been a number of commercial offerings of Wi-Fi location systems targeted at indoor positioning. (See, e.g., Kavitha Muthukrishnan, Maria Lijding, Paul Havinga, Towards Smart Surroundings: Enabling Techniques and Technologies for Localization, Proceedings of the International Workshop on Location and Context-Awareness (LoCA 2005) at Pervasive 2005, May 2005, and Hazas, M., Scott, J., Krumm, J.: Location-Aware Computing Comes of Age.
IEEE Computer, 37(2):95-97, Feb 2004 005, Pa005, Pages 350-362.) These systems are designed to address asset and people tracking within a controlled environment like a corporate campus, a hospital facility or a shipping yard.
The classic example is having a system that can monitor the exact location of the crash cart within the hospital so that when there is a cardiac arrest the hospital staff doesn't waste time locating the device. The accuracy requirements for these use cases are very demanding typically calling for 1-3 meter accuracy.
[00051 These systems use a variety of techniques to fine tune their accuracy including conducting detailed site surveys of every square foot of the campus to measure radio signal propagation. They also require a constant network connection so that the access point and the client radio can exchange synchronization information similar to how A-GPS works. While these systems are becoming more reliable for indoor use cases, they are ineffective in any wide-area deployment. It is impossible to conduct the kind of detailed site survey required across an entire city and there is no way to rely on a constant communication channel with 802.11 access points across an entire metropolitan area to the extent required by these systems. Most importantly outdoor radio propagation is fundamentally different than indoor radio propagation rendering these indoor positioning algorithms almost useless in a wide-area scenario.
The required accuracy of indoor WLAN based positioning systems, makes it hard to use radio channel modeling and it is considered as a research topic in that domain.
In addition, none of the WLAN based positioning systems to date have distinguished between access points, and current methods treat all WLAN access points the same.
[0006] Figure 1 depicts a Wi-Fi positioning system (WPS). The positioning system includes positioning software [103] that resides on a computing device [101]. Throughout a particular coverage area there are fixed wireless access points [102] that broadcast information using control/common channel broadcast signals. The client device monitors the broadcast signal or requests its transmission via a probe request. Each access point contains a unique hardware identifier known as a MAC address. The client positioning software receives signal beacons from the 802.11 access points in range and calculates the geographic location of the computing device using characteristics from the signal beacons. Those characteristics include the unique identifier of the 802.11 access point, known as the MAC address, and the strengths of the signal reaching the client device. The client software compares the observed 802.11 access points with those in its reference database [104] of access points, which may or may not reside on the device as well. The reference database contains the calculated geographic locations and power profile of all the access points the gathering system has collected. The power profile may be generated from a collection of readings that represent the power of the signal from various locations. Using these known locations, the client software calculates the relative position of the user device [101] and determines its geographic coordinates in the form of latitude and longitude readings. Those readings are then fed to location-based applications such as friend finders, local search web sites, fleet management systems and E911 services.
Summary [0007] The invention provides methods and systems for estimating position using WLAN (e.g., Wi-Fi) access point radio propagation characteristics in a WLAN location based service.
[0008] Aspects of the invention classifying WLAN access points based on a radio channel model can use any channel model, and the invention is independent of any specific channel model.
[0009] Under one aspect of the invention, a location-based services system has a plurality of Wi-Fi access points in a target area. The Wi-Fi access points are positioned at geographic locations and have signal coverage areas. A
method of characterizing at least one of the Wi-Fi access points comprises determining the geographic location of the Wi-Fi access point, dividing the signal coverage area of the Wi-Fi access point into at least one section, and detei mining radio propagation characteristics for each section. The radio propagation characteristics of each section characterize a radio channel of the Wi-Fi access point, and the characterization can be used in a location algorithm.
[0010] Under another aspect of the invention, the signal coverage area is characterized as one section.
[0011] Under another aspect of the invention, the signal coverage is divided into more than one section. Under certain embodiments, radials emanating outward from the Wi-Fi access point form the sections. Under further embodiments, sections are formed based on a distance from the Wi-Fi access point. Under yet further embodiments, sections are formed based on both radials and distances from the Wi-Fi access point.
[0012] Under another aspect of the invention, a plurality of received signal power values within the signal coverage area is measured. Each received signal power value is measured at an associated position relative to the Wi-Fi access point. The sections are determined based on the plurality of received signal power values and associated positions.
[0013] Under another aspect of the invention, the radio propagation characteristics include a signal power-distance gradient.
[0014] Under another aspect of the invention, the signal power-distance gradient for each section is determined by measuring a plurality of received signal power values within the signal coverage area, each received signal power value being measured at an associated position relative to the Wi-Fi access point, performing a linear regression on the plurality of received signal power values and associated positions, and using a slope determined by the linear regression to calculate the signal power-distance gradient.
4 [0015] Under another aspect of the invention, the signal power-distance gradient for each section is determined by measuring a plurality of received signal power values within the signal coverage area, each received signal power value being measured at an associated position relative to the Wi-Fi access point. A
distance corresponding to each of the signal power values is calculated, the distances being measured from the associated positions of the signal power values to the geographic loCations of the Wi-Fi access points. An average radius of signal coverage is estimated using the standard deviation of the distances, and the average radius of signal coverage is used to calculate the signal power-distance gradient.
[0016] Under another aspect of the invention, the position of a Wi-Fi enabled device is estimated by the Wi-Fi enabled device communicating with Wi-Fi access points within range of the Wi-Fi enabled device to cause the Wi-Fi access points to transmit signals. The Wi-Fi enabled device receives the signals transmitted by the Wi-Fi access points and identifies the Wi-Fi access points.
Calculated locations and estimated radio propagation characteristics of the Wi-Fi access points are retrieved from a reference database using Wi-Fi access point identifiers. The calculated locations and the estimated radio propagation characteristics are used to estimate the position of the Wi-Fi enabled device.
Brief Description Of Drawings [0017] In the drawings, Figure 1 depicts certain embodiments of a Wi-Fi positioning system;
Figure 2 depicts a line fit to RSS samples, defining an example access point coverage area according to certain embodiments of the invention;
Figure 3 depicts dividing a coverage area of an access point into sectors according to certain embodiments of the invention;
Figure 4 depicts a coverage area of an access point characterized with multiple power distance gradients according to certain embodiments of the invention;
Figure 5 depicts a coverage area of an access point divided into multiple sectors and tiers according to certain embodiments of the invention; and Figure 6 depicts RSS sample statistics in a two dimensional surface identifying the radius of the coverage area according to certain embodiments of the invention.
Detailed Description 100181 Embodiments of the invention provide a methodology to classify WLAN access points based on their radio propagation characteristics in a WLAN
based positioning system and to increase the accuracy of position, velocity and bearing estimations. Under certain embodiments, radio propagation characteristics of WLAN access points are estimated based on RSS samples in their coverage area. For example, radio propagation characteristics can be characterized by finding one or more signal power-distance gradients for at least one of the WLAN access points.
[0019] There are different physical phenomena that impact Received Signal Strength (RSS) variation in the dimensions of space and time. The RSS
variation is categorized as either fast fading or slow fading. The techniques disclosed herein focus on estimating the slow fading characteristics of the RSS and also assess the estimation quality and quantify the estimation.
[0020] Embodiments of the present invention build on techniques, systems and methods disclosed in earlier filed applications, including but not limited to U.S. Patent Application No. 11/261,848, entitled Location Beacon Database,U
U.S.
Patent Application No. 11/261, 898, entitled Server for Updating Location Beacon Database, U.S. Patent Application No. 11/261,987, entitled Method and System for Building a Location Beacon Database, and U.S. Patent Application No. 11/261,988, entitled Location-Based Services that Choose Location Algorithms Based on Number of Detected Access Points Within Range of User Device, all filed on October 28, 2005.
Those applications taught specific ways to gather high quality location data for Wi-Fi access points so that such data may be used in location based services to determine the geographic position of a Wi-Fi-enabled device utilizing such services and techniques of using said location data to estimate the position of a system user. The present techniques, however, are not limited to systems and methods disclosed in the incorporated patent applications. Thus, while reference to such systems and applications may be helpful, it is not believed necessary to understand the present embodiments or inventions.
[0021] Figure 2 depicts an example of embodiments of the invention characterizing radio propagation characteristics of WLAN access points by estimating a signal power-distance gradient for a WLAN access point in a WLAN
based positioning system. The coverage area of a WLAN access point may be used to find a signal power-distance gradient. The minimum RSS [204] is limited by sensitivity of the scanner. Whereas, the maximum RSS [203] may be assumed the same for all of the WLAN access points because the maximum transmit power is defined as part of the Wi-Fi standard. Therefore, the coverage area of a WLAN access point is directly a function of the signal power-distance gradient of the WLAN access point.
[0022] Figure 2 represents RSS samples [201] as points on a graph plotting RSS power (in dB) [205] versus distance of the RSS sample from the access point (in dB) [206]. A signal power-distance gradient a can be determined by fitting a line [202] to the RSS sample points [201], where the slope of the line is equal to the signal power-distance gradient. Because a WLAN based positioning system according to embodiments of the invention use radio waves of public and private WLAN access points in order to continuously estimate position of a user, aspects of the invention increase the accuracy of location estimation by using individual radio propagation characteristics of each WLAN access point, rather than a standard value.
[0023] Under other embodiments of the present invention, the coverage area of a WLAN access point is divided into sectors, and radio propagation characteristics are determined for each sector, e.g., a signal power-distance gradient is found for each sector. For example, in a metropolitan area, the radio propagation characteristics of an access point is not symmetric across its coverage area, i.e., the characteristics vary in different directions. Under embodiments of the invention, the 360 degree coverage area of the WLAN access point is divided into multiple sectors when coverage of the WLAN access point is not symmetric in all of the directions. The sectors may be divided according to radials emanating from the estimated location of the WLAN access point.
[0024] For simplicity, the sectors may be referenced from the same axis, for example, the north direction. Because the radio propagation characteristics of the WLAN access point needs to be found in each direction, there is a need to have enough RSS samples in each sector. Based on the statistics of the number of RSS
power samples and their distribution, a number of sectors can be determined.
Increasing the number of sectors increases the resolution of the radio propagation characteristics because averaging is occurred in a smaller sector. However, this is conditioned on having enough RSS samples to be able to estimate the radio propagation characteristics, e.g., power distance gradient, in each sector accurately.
[0025] Figure 3 depicts an example of a WLAN access point [302] with its coverage area divided into four sectors [301]. The number of sectors varies from one WLAN access point to another, and it is selected for each WLAN access point separately based on the number of RSS samples and the RSS sample distribution in the WLAN access point coverage area. For example, in a metropolitan WLAN based positioning system, if the RSS samples for a given WLAN access point are non-uniform, then a relatively low number of sectors will be used for that WLAN access point. If RSS samples from the coverage area of a WLAN access point indicate different radio propagation characteristics, such as different signal power-distance gradients, in different directions, the coverage area of that WLAN access point is divided into multiple sectors.
[0026] For example, if a WLAN access point is facing an open area from one side and residential area from the other side, the coverage area can be divided into two sectors, and corresponding radio propagation characteristics may be determined for each sector. In at least one embodiment, for the general case of a metropolitan positioning system, a useful maximum number of sectors is in the range of four to six, because distinguishing between sectors for higher numbers of sectors may be of limited value. The minimum number of sectors can be as small as one, which means, for example, that one signal power-distance gradient is used for the whole coverage area.
[0027] After selecting number of sectors, radio propagation characteristics need to be calculated for each sector. Note that if number of RSS samples in one sector is not enough to estimate radio propagation characteristics in that sector, the average of the characteristics of the adjacent sectors may be used.
[0028] Under one embodiment of the invention, the radio propagation characteristics of a WLAN access point can be presented by a piecewise linear estimation. This may be accomplished by dividing the coverage area of the WLAN access point into multiple tiers and finding the radio propagation characteristics for each tier. This method can be used to increase the accuracy of RSS power to distance translation, e.g., when a WLAN access point coverage area consists of indoor and outdoor environments. Thus, this approach may be used to capture indoor and outdoor radio propagation characteristics differently by estimating a signal power-distance gradient for each tier.
[0029] Figure 4 depicts an example of RSS samples for a WLAN access point in which the RSS samples can be presented clearly with two signal power-distance gradient values, one for use in the vicinity of the access point and the other for use at greater distances. Figure 4 present RSS samples plotted as RSS
power [405] versus distance [406] ftom the WLAN access point. The minimum scanner sensitivity [404] and maximum RSS value [403] are also shown. The coverage area of a WLAN access point is divided into multiple tiers when it is necessary. For example, if it is known that the coverage area of a WLAN access point is partly indoor and partly outdoor. Alternatively, the need to use the multi-tier approach to characterize coverage area of a WLAN access point may be detected by observing the RSS samples. A sharp change in the average decay of power values of the RSS samples, as illustrated by the differing slopes of a first cluster of RSS samples [401] and a second cluster of RSS samples [402], may indicate an environment change. A useful number of tiers has been found to be two.
[0030] Figure 5 depicts an embodiment dividing the coverage area into a combination of sectors and tiers. In this case, the coverage area of a WLAN
access point [501] can be divided to multiple sectors [502], and each sector can be further divided into multiple tiers [503], thus forming multiple sections [504].
The number of sectors and tiers, and the corresponding radio propagation characteristics, are considered part of the attributes of each WLAN access point when it is stored in the reference database [104], and these attributes are retrieved by the end user and used to estimate the user location.
[0031] Under one embodiment of the invention, the radio propagation characteristics of a WLAN access point may be estimated using the signal power-distance gradient for each sector, which is found based on RSS samples in the designated area. One possible approach to finding a signal power-distance gradient is by fitting a line to RSS samples with power (in dB) as a function of distance (in dB), as was discussed above in connection with Figure 2. Due to power variation in a metropolitan indoor and outdoor WLAN positioning system, this method may have low accuracy for a typical number of RSS samples in a typical metropolitan environment.
[0032] Under one aspect of the invention, a novel approach to finding a signal power-distance gradient is disclosed, wherein the average radius of the coverage area of a WLAN access point is calculated and used to estimate the signal power-distance gradient. The average radius of coverage area can be used as an indictor of the signal power-distance gradient because the signal power-distance gradient is the ratio of RSS power to distance from the WLAN access point. Referring again to Figure 2, if the points corresponding to the minimum RSS [204] and the maximum RSS [203] are considered, the power difference between the minimum and the maximum power points are the same for all the access points, because the minimum power is bounded by the sensitivity of the scanner and the maximum power is the maximum access point transmit power. The sensitivity of the scanners collecting the RSS samples is nearly identical in the systematic scanning scenario, and the maximum transmit power is limited by, e.g., the FCC, for WLAN access points and can be assumed the same for all the access points.
Therefore, the radius of coverage area is directly dependent on the signal power-distance gradient value.
[0033] In other words, the sensitivity of the scanner receiver limits the minimum RSS [204] which can be detected by the scanner. Therefore, the signal power-distance gradient value directly impacts the radius of coverage area of the WLAN access point. Because the receiver sensitivity is the same for all scanning devices taking RSS samples, the radius of coverage area of the WLAN access point can be used as an indicator of the value of signal power-distance gradient, as was shown in Figure 2.
[0034] In order to find the radius of coverage area of the WLAN access point and avoid the impact of fast fading on the RSS power reading, and subsequently on the coverage, the standard deviation of the radius of coverage area instead of absolute radius of coverage area is used. In other words, absolute value of the radius of coverage area depends on a limited number of readings at the edge of the coverage, but standard deviation is calculated based on the total number of RSS samples and reduces the impact of power variation at the edge of the coverage area, while at the same time indicating the size of the coverage area.
[0035] Figure 6 depicts a coverage area of an access point [601] and power distribution [604] as a function of the latitude [602] and longitude [603] of the power readings. The standard deviation of RSS samples referenced to the location of access point [601] is directly correlated to the average radius of the coverage.
[0036] When the coverage area is not divided into multiple sections, and the whole area is considered as one area, the standard deviation is calculated based on all of the RSS readings around the access point. If the total number of RSS
samples of the access point is denoted by Nand corresponding latitude and longitude of RSS sample i are denoted by (lath long), the standard deviation, cs., of the radius of coverage area is calculated as follows:
cy Vax2 In which I(d xj)2 2 i=1 = N > 1 a x =0,N =1, 1(C 1 02 2 tr.-1 = N > 1 ay =0,N =1, [0037] The variables dxi and dyi are the distances of power sample from the WLAN access point in the X and Y directions in Cartesian coordinates. The standard deviation calculation can be simplified as follows:
= lot _L long In which 1(lat ¨ at)2 1 N >1 a lot =
alai =0,1V =1, E(longi ¨ ong)2 2 1 N >1 a long =
N ¨1 along = 0, N = 1, 100381 In this equation, (lat, long) is the calculated location of the WLAN
access point. The average radius of coverage is calculated based on a Cartesian presentation of location. Calculation of the radius of coverage can also be simplified by considering latitude and longitude without converting them to Cartesian coordinates. If the coverage area is divided into multiple sectors, the standard deviation is calculated based on the distance of RSS samples from the WLAN access point, which can be considered in one dimension. Therefore, the standard deviation is calculated as follows:
i)2 __________________________ ,N>1 = 0,N =1, [0039] In which d, is distance of power sample i from the WLAN access point.
[0040] The standard deviation of a radius of the coverage area is translated to the signal power-distance gradient using following equation:
a = amin, if (cr > o-.) a = an., if (u < min) log(o-) ¨ log(o-min ) = a.õ+(amin a.õ)( _____________________________ ), otherwise.
log(a) ¨ log(o-õõ,, ) [0041] In which amin and a. are minimum and maximum values of the signal power-distance gradient, and anijn and a.ax are the minimum and maximum thresholds of the WLAN access point coverage. The values of a.. and a.ax are dependent on the environment in which the WLAN devices are operating. One example of useful values for the minimum and maximum signal power-distance gradients for a metropolitan WLAN based positioning systems are as follows:
am,õ = 2, aniax = 6.
In this case, the maximum value of a is the typical maximum value for an urban area.
[0042] The minimum and the maximum values of the standard deviation are found based on typical minimum and maximum radii of coverage of WLAN
access points, which may be found empirically. Useful minimum and maximum radii of coverage of WLAN APs are 60 and 700 meters, respectively. If the coverage is considered as five-sigmia value, the minimum and maximum sigma value can be calculated.
[0043] In the case of multi tier approach, after finding the boundary of each tier, the signal power-distance gradient for each tier may be found by fitting a line to RSS samples within each tier using the method discussed in connection with Figure 2 above. The standard deviation approach cannot be used, because the minimum and maximum power values are not known for each tier, as it was known for the whole coverage area. Figure 4 depicts an example of a multi-tier access point and illustrates the exact transition point from the first cluster of RSS
samples [401] and the second cluster of RSS samples is not known, as some of the RSS samples considered to belong to the first cluster [401] may actually belong to the second cluster [402]. Estimating this transition point introduces error using the standard deviation approach.
[0044] According to embodiments of the invention, signal power-distance gradient(s) for each WLAN access point may be used by the user to find its distance to each WLAN access point in range and consequently locate itself.
Signal power-distance gradient can be used in the following equation to find the distance:
d=al _____________ "RSS
[0045] The notation Pos is the received power from a WLAN access point in watts and K is a constant number aggregating all other parameters. The value of d can be normalized to K by assuming K equal to one without sacrificing accuracy.
Assuming K equal to one is the same as changing the scale of the distance measurement, and because it can be made the same for all access points, normalizing K does not impact the accuracy of position estimation.
100461 Under aspects of the invention, the location of access point, (lat ,Iong), may be calculated. If the exact location of an access point is not known, the RSS
samples and their corresponding locations can be used to estimate the location of the access point. For example, location of the access point can be found by finding the center of power readings as follows:
lat = _________ 1=1 Ilong;
long = ________________ Wherein the total number of power samples is equal to N.
[0047] Charactering the unique radio propagation characteristics of each WLAN access point in a location system, instead of using one set of characteristics for all the WLAN access points, increases the accuracy of position, speed of travel, and direction of travel estimations in a WLAN based positioning system. One example of a positioning algorithm is show below, which illustrates the use of signal power-distance gradients estimated according to embodiments of the invention. This example is a triangulation algorithm weighted according to the distance of the user from the access points.
[0048] If a user detects N number of access points with a corresponding RSS
value of Pi, a signal power-distance gradient of ai, a latitude of lati, and a longitude of longi, the distance of the user to the access points is calculated as follows:
\I
P, [0049] Latitude and longitude of the user, U/a, and thong, can be found as follows:
U= __________________ int N 1 IT
long, = _______________ ' 4; d ' "long N 1 ,=I NI
[0050] Under another aspect of the invention, the RSS value reading by the end user can be notmalized, and the RSS power reading can be used to select the correct value of radio propagation characteristics, e.g., a signal power-distance gradient, in the case of multi tier approach. When a coverage area is divided into multiple tiers with piecewise linear estimation of the coverage area, the user must be able to determine in which tier he is located, and use the radio propagation characteristics. In this case, there is a need to normalize the RSS power reading across different hardware and different Wi-Fi receiver implementations. In order to notinalize the RSS power reading, the minimum and the maximum power sensitivity of the user's device are mapped to the dynamic power range of the scanner used to supply data to the reference database [104].
[0051] If the scanners used to supply data to the reference database do not have a standard dynamic power range, the same normalization method may be used to map the individual dynamic ranges of the different scanning devices to a standard dynamic range. Thus, this method can be used in a WLAN positioning system when the hardware differs between scanners. In this case, a standard dynamic range for the power is selected by selecting a minimum and a maximum value for power reading, and all readings from all the different devices are mapped to this range.
[0052] For example, if the standard minimum power and the maximum power values are set to -100 dBm and -40 dBm, respectively, and a user device's minimum and maximum range is between ¨90 dBm and ¨60 dBm, the power readings of the user is nofinalized as follows:
Pnew =[Pold ¨ + (-100) [0053] It will be appreciated that the scope of the present invention is not limited to the above-described embodiments, but rather is defined by the appended claims, and these claims will encompass modifications of and improvements to what has been described.
[0054] What is claimed is:
distance corresponding to each of the signal power values is calculated, the distances being measured from the associated positions of the signal power values to the geographic loCations of the Wi-Fi access points. An average radius of signal coverage is estimated using the standard deviation of the distances, and the average radius of signal coverage is used to calculate the signal power-distance gradient.
[0016] Under another aspect of the invention, the position of a Wi-Fi enabled device is estimated by the Wi-Fi enabled device communicating with Wi-Fi access points within range of the Wi-Fi enabled device to cause the Wi-Fi access points to transmit signals. The Wi-Fi enabled device receives the signals transmitted by the Wi-Fi access points and identifies the Wi-Fi access points.
Calculated locations and estimated radio propagation characteristics of the Wi-Fi access points are retrieved from a reference database using Wi-Fi access point identifiers. The calculated locations and the estimated radio propagation characteristics are used to estimate the position of the Wi-Fi enabled device.
Brief Description Of Drawings [0017] In the drawings, Figure 1 depicts certain embodiments of a Wi-Fi positioning system;
Figure 2 depicts a line fit to RSS samples, defining an example access point coverage area according to certain embodiments of the invention;
Figure 3 depicts dividing a coverage area of an access point into sectors according to certain embodiments of the invention;
Figure 4 depicts a coverage area of an access point characterized with multiple power distance gradients according to certain embodiments of the invention;
Figure 5 depicts a coverage area of an access point divided into multiple sectors and tiers according to certain embodiments of the invention; and Figure 6 depicts RSS sample statistics in a two dimensional surface identifying the radius of the coverage area according to certain embodiments of the invention.
Detailed Description 100181 Embodiments of the invention provide a methodology to classify WLAN access points based on their radio propagation characteristics in a WLAN
based positioning system and to increase the accuracy of position, velocity and bearing estimations. Under certain embodiments, radio propagation characteristics of WLAN access points are estimated based on RSS samples in their coverage area. For example, radio propagation characteristics can be characterized by finding one or more signal power-distance gradients for at least one of the WLAN access points.
[0019] There are different physical phenomena that impact Received Signal Strength (RSS) variation in the dimensions of space and time. The RSS
variation is categorized as either fast fading or slow fading. The techniques disclosed herein focus on estimating the slow fading characteristics of the RSS and also assess the estimation quality and quantify the estimation.
[0020] Embodiments of the present invention build on techniques, systems and methods disclosed in earlier filed applications, including but not limited to U.S. Patent Application No. 11/261,848, entitled Location Beacon Database,U
U.S.
Patent Application No. 11/261, 898, entitled Server for Updating Location Beacon Database, U.S. Patent Application No. 11/261,987, entitled Method and System for Building a Location Beacon Database, and U.S. Patent Application No. 11/261,988, entitled Location-Based Services that Choose Location Algorithms Based on Number of Detected Access Points Within Range of User Device, all filed on October 28, 2005.
Those applications taught specific ways to gather high quality location data for Wi-Fi access points so that such data may be used in location based services to determine the geographic position of a Wi-Fi-enabled device utilizing such services and techniques of using said location data to estimate the position of a system user. The present techniques, however, are not limited to systems and methods disclosed in the incorporated patent applications. Thus, while reference to such systems and applications may be helpful, it is not believed necessary to understand the present embodiments or inventions.
[0021] Figure 2 depicts an example of embodiments of the invention characterizing radio propagation characteristics of WLAN access points by estimating a signal power-distance gradient for a WLAN access point in a WLAN
based positioning system. The coverage area of a WLAN access point may be used to find a signal power-distance gradient. The minimum RSS [204] is limited by sensitivity of the scanner. Whereas, the maximum RSS [203] may be assumed the same for all of the WLAN access points because the maximum transmit power is defined as part of the Wi-Fi standard. Therefore, the coverage area of a WLAN access point is directly a function of the signal power-distance gradient of the WLAN access point.
[0022] Figure 2 represents RSS samples [201] as points on a graph plotting RSS power (in dB) [205] versus distance of the RSS sample from the access point (in dB) [206]. A signal power-distance gradient a can be determined by fitting a line [202] to the RSS sample points [201], where the slope of the line is equal to the signal power-distance gradient. Because a WLAN based positioning system according to embodiments of the invention use radio waves of public and private WLAN access points in order to continuously estimate position of a user, aspects of the invention increase the accuracy of location estimation by using individual radio propagation characteristics of each WLAN access point, rather than a standard value.
[0023] Under other embodiments of the present invention, the coverage area of a WLAN access point is divided into sectors, and radio propagation characteristics are determined for each sector, e.g., a signal power-distance gradient is found for each sector. For example, in a metropolitan area, the radio propagation characteristics of an access point is not symmetric across its coverage area, i.e., the characteristics vary in different directions. Under embodiments of the invention, the 360 degree coverage area of the WLAN access point is divided into multiple sectors when coverage of the WLAN access point is not symmetric in all of the directions. The sectors may be divided according to radials emanating from the estimated location of the WLAN access point.
[0024] For simplicity, the sectors may be referenced from the same axis, for example, the north direction. Because the radio propagation characteristics of the WLAN access point needs to be found in each direction, there is a need to have enough RSS samples in each sector. Based on the statistics of the number of RSS
power samples and their distribution, a number of sectors can be determined.
Increasing the number of sectors increases the resolution of the radio propagation characteristics because averaging is occurred in a smaller sector. However, this is conditioned on having enough RSS samples to be able to estimate the radio propagation characteristics, e.g., power distance gradient, in each sector accurately.
[0025] Figure 3 depicts an example of a WLAN access point [302] with its coverage area divided into four sectors [301]. The number of sectors varies from one WLAN access point to another, and it is selected for each WLAN access point separately based on the number of RSS samples and the RSS sample distribution in the WLAN access point coverage area. For example, in a metropolitan WLAN based positioning system, if the RSS samples for a given WLAN access point are non-uniform, then a relatively low number of sectors will be used for that WLAN access point. If RSS samples from the coverage area of a WLAN access point indicate different radio propagation characteristics, such as different signal power-distance gradients, in different directions, the coverage area of that WLAN access point is divided into multiple sectors.
[0026] For example, if a WLAN access point is facing an open area from one side and residential area from the other side, the coverage area can be divided into two sectors, and corresponding radio propagation characteristics may be determined for each sector. In at least one embodiment, for the general case of a metropolitan positioning system, a useful maximum number of sectors is in the range of four to six, because distinguishing between sectors for higher numbers of sectors may be of limited value. The minimum number of sectors can be as small as one, which means, for example, that one signal power-distance gradient is used for the whole coverage area.
[0027] After selecting number of sectors, radio propagation characteristics need to be calculated for each sector. Note that if number of RSS samples in one sector is not enough to estimate radio propagation characteristics in that sector, the average of the characteristics of the adjacent sectors may be used.
[0028] Under one embodiment of the invention, the radio propagation characteristics of a WLAN access point can be presented by a piecewise linear estimation. This may be accomplished by dividing the coverage area of the WLAN access point into multiple tiers and finding the radio propagation characteristics for each tier. This method can be used to increase the accuracy of RSS power to distance translation, e.g., when a WLAN access point coverage area consists of indoor and outdoor environments. Thus, this approach may be used to capture indoor and outdoor radio propagation characteristics differently by estimating a signal power-distance gradient for each tier.
[0029] Figure 4 depicts an example of RSS samples for a WLAN access point in which the RSS samples can be presented clearly with two signal power-distance gradient values, one for use in the vicinity of the access point and the other for use at greater distances. Figure 4 present RSS samples plotted as RSS
power [405] versus distance [406] ftom the WLAN access point. The minimum scanner sensitivity [404] and maximum RSS value [403] are also shown. The coverage area of a WLAN access point is divided into multiple tiers when it is necessary. For example, if it is known that the coverage area of a WLAN access point is partly indoor and partly outdoor. Alternatively, the need to use the multi-tier approach to characterize coverage area of a WLAN access point may be detected by observing the RSS samples. A sharp change in the average decay of power values of the RSS samples, as illustrated by the differing slopes of a first cluster of RSS samples [401] and a second cluster of RSS samples [402], may indicate an environment change. A useful number of tiers has been found to be two.
[0030] Figure 5 depicts an embodiment dividing the coverage area into a combination of sectors and tiers. In this case, the coverage area of a WLAN
access point [501] can be divided to multiple sectors [502], and each sector can be further divided into multiple tiers [503], thus forming multiple sections [504].
The number of sectors and tiers, and the corresponding radio propagation characteristics, are considered part of the attributes of each WLAN access point when it is stored in the reference database [104], and these attributes are retrieved by the end user and used to estimate the user location.
[0031] Under one embodiment of the invention, the radio propagation characteristics of a WLAN access point may be estimated using the signal power-distance gradient for each sector, which is found based on RSS samples in the designated area. One possible approach to finding a signal power-distance gradient is by fitting a line to RSS samples with power (in dB) as a function of distance (in dB), as was discussed above in connection with Figure 2. Due to power variation in a metropolitan indoor and outdoor WLAN positioning system, this method may have low accuracy for a typical number of RSS samples in a typical metropolitan environment.
[0032] Under one aspect of the invention, a novel approach to finding a signal power-distance gradient is disclosed, wherein the average radius of the coverage area of a WLAN access point is calculated and used to estimate the signal power-distance gradient. The average radius of coverage area can be used as an indictor of the signal power-distance gradient because the signal power-distance gradient is the ratio of RSS power to distance from the WLAN access point. Referring again to Figure 2, if the points corresponding to the minimum RSS [204] and the maximum RSS [203] are considered, the power difference between the minimum and the maximum power points are the same for all the access points, because the minimum power is bounded by the sensitivity of the scanner and the maximum power is the maximum access point transmit power. The sensitivity of the scanners collecting the RSS samples is nearly identical in the systematic scanning scenario, and the maximum transmit power is limited by, e.g., the FCC, for WLAN access points and can be assumed the same for all the access points.
Therefore, the radius of coverage area is directly dependent on the signal power-distance gradient value.
[0033] In other words, the sensitivity of the scanner receiver limits the minimum RSS [204] which can be detected by the scanner. Therefore, the signal power-distance gradient value directly impacts the radius of coverage area of the WLAN access point. Because the receiver sensitivity is the same for all scanning devices taking RSS samples, the radius of coverage area of the WLAN access point can be used as an indicator of the value of signal power-distance gradient, as was shown in Figure 2.
[0034] In order to find the radius of coverage area of the WLAN access point and avoid the impact of fast fading on the RSS power reading, and subsequently on the coverage, the standard deviation of the radius of coverage area instead of absolute radius of coverage area is used. In other words, absolute value of the radius of coverage area depends on a limited number of readings at the edge of the coverage, but standard deviation is calculated based on the total number of RSS samples and reduces the impact of power variation at the edge of the coverage area, while at the same time indicating the size of the coverage area.
[0035] Figure 6 depicts a coverage area of an access point [601] and power distribution [604] as a function of the latitude [602] and longitude [603] of the power readings. The standard deviation of RSS samples referenced to the location of access point [601] is directly correlated to the average radius of the coverage.
[0036] When the coverage area is not divided into multiple sections, and the whole area is considered as one area, the standard deviation is calculated based on all of the RSS readings around the access point. If the total number of RSS
samples of the access point is denoted by Nand corresponding latitude and longitude of RSS sample i are denoted by (lath long), the standard deviation, cs., of the radius of coverage area is calculated as follows:
cy Vax2 In which I(d xj)2 2 i=1 = N > 1 a x =0,N =1, 1(C 1 02 2 tr.-1 = N > 1 ay =0,N =1, [0037] The variables dxi and dyi are the distances of power sample from the WLAN access point in the X and Y directions in Cartesian coordinates. The standard deviation calculation can be simplified as follows:
= lot _L long In which 1(lat ¨ at)2 1 N >1 a lot =
alai =0,1V =1, E(longi ¨ ong)2 2 1 N >1 a long =
N ¨1 along = 0, N = 1, 100381 In this equation, (lat, long) is the calculated location of the WLAN
access point. The average radius of coverage is calculated based on a Cartesian presentation of location. Calculation of the radius of coverage can also be simplified by considering latitude and longitude without converting them to Cartesian coordinates. If the coverage area is divided into multiple sectors, the standard deviation is calculated based on the distance of RSS samples from the WLAN access point, which can be considered in one dimension. Therefore, the standard deviation is calculated as follows:
i)2 __________________________ ,N>1 = 0,N =1, [0039] In which d, is distance of power sample i from the WLAN access point.
[0040] The standard deviation of a radius of the coverage area is translated to the signal power-distance gradient using following equation:
a = amin, if (cr > o-.) a = an., if (u < min) log(o-) ¨ log(o-min ) = a.õ+(amin a.õ)( _____________________________ ), otherwise.
log(a) ¨ log(o-õõ,, ) [0041] In which amin and a. are minimum and maximum values of the signal power-distance gradient, and anijn and a.ax are the minimum and maximum thresholds of the WLAN access point coverage. The values of a.. and a.ax are dependent on the environment in which the WLAN devices are operating. One example of useful values for the minimum and maximum signal power-distance gradients for a metropolitan WLAN based positioning systems are as follows:
am,õ = 2, aniax = 6.
In this case, the maximum value of a is the typical maximum value for an urban area.
[0042] The minimum and the maximum values of the standard deviation are found based on typical minimum and maximum radii of coverage of WLAN
access points, which may be found empirically. Useful minimum and maximum radii of coverage of WLAN APs are 60 and 700 meters, respectively. If the coverage is considered as five-sigmia value, the minimum and maximum sigma value can be calculated.
[0043] In the case of multi tier approach, after finding the boundary of each tier, the signal power-distance gradient for each tier may be found by fitting a line to RSS samples within each tier using the method discussed in connection with Figure 2 above. The standard deviation approach cannot be used, because the minimum and maximum power values are not known for each tier, as it was known for the whole coverage area. Figure 4 depicts an example of a multi-tier access point and illustrates the exact transition point from the first cluster of RSS
samples [401] and the second cluster of RSS samples is not known, as some of the RSS samples considered to belong to the first cluster [401] may actually belong to the second cluster [402]. Estimating this transition point introduces error using the standard deviation approach.
[0044] According to embodiments of the invention, signal power-distance gradient(s) for each WLAN access point may be used by the user to find its distance to each WLAN access point in range and consequently locate itself.
Signal power-distance gradient can be used in the following equation to find the distance:
d=al _____________ "RSS
[0045] The notation Pos is the received power from a WLAN access point in watts and K is a constant number aggregating all other parameters. The value of d can be normalized to K by assuming K equal to one without sacrificing accuracy.
Assuming K equal to one is the same as changing the scale of the distance measurement, and because it can be made the same for all access points, normalizing K does not impact the accuracy of position estimation.
100461 Under aspects of the invention, the location of access point, (lat ,Iong), may be calculated. If the exact location of an access point is not known, the RSS
samples and their corresponding locations can be used to estimate the location of the access point. For example, location of the access point can be found by finding the center of power readings as follows:
lat = _________ 1=1 Ilong;
long = ________________ Wherein the total number of power samples is equal to N.
[0047] Charactering the unique radio propagation characteristics of each WLAN access point in a location system, instead of using one set of characteristics for all the WLAN access points, increases the accuracy of position, speed of travel, and direction of travel estimations in a WLAN based positioning system. One example of a positioning algorithm is show below, which illustrates the use of signal power-distance gradients estimated according to embodiments of the invention. This example is a triangulation algorithm weighted according to the distance of the user from the access points.
[0048] If a user detects N number of access points with a corresponding RSS
value of Pi, a signal power-distance gradient of ai, a latitude of lati, and a longitude of longi, the distance of the user to the access points is calculated as follows:
\I
P, [0049] Latitude and longitude of the user, U/a, and thong, can be found as follows:
U= __________________ int N 1 IT
long, = _______________ ' 4; d ' "long N 1 ,=I NI
[0050] Under another aspect of the invention, the RSS value reading by the end user can be notmalized, and the RSS power reading can be used to select the correct value of radio propagation characteristics, e.g., a signal power-distance gradient, in the case of multi tier approach. When a coverage area is divided into multiple tiers with piecewise linear estimation of the coverage area, the user must be able to determine in which tier he is located, and use the radio propagation characteristics. In this case, there is a need to normalize the RSS power reading across different hardware and different Wi-Fi receiver implementations. In order to notinalize the RSS power reading, the minimum and the maximum power sensitivity of the user's device are mapped to the dynamic power range of the scanner used to supply data to the reference database [104].
[0051] If the scanners used to supply data to the reference database do not have a standard dynamic power range, the same normalization method may be used to map the individual dynamic ranges of the different scanning devices to a standard dynamic range. Thus, this method can be used in a WLAN positioning system when the hardware differs between scanners. In this case, a standard dynamic range for the power is selected by selecting a minimum and a maximum value for power reading, and all readings from all the different devices are mapped to this range.
[0052] For example, if the standard minimum power and the maximum power values are set to -100 dBm and -40 dBm, respectively, and a user device's minimum and maximum range is between ¨90 dBm and ¨60 dBm, the power readings of the user is nofinalized as follows:
Pnew =[Pold ¨ + (-100) [0053] It will be appreciated that the scope of the present invention is not limited to the above-described embodiments, but rather is defined by the appended claims, and these claims will encompass modifications of and improvements to what has been described.
[0054] What is claimed is:
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of characterizing at least one of Wi-Fi access points, using the coverage area of the Wi-Fi access point, so that the characterization may be used later to effectively weigh signals transmitted by said Wi-Fi access point when performing a location estimation, the method of characterization comprising:
determining the geographic location of the Wi-Fi access points; for each Wi-Fi access point, measuring a plurality of power values for signals transmitted by a corresponding Wi-Fi access point, each power value being measured at position relative to each corresponding Wi-Fi access point;
determining a signal coverage area of each Wi-Fi access point based on said measured plurality of power values;
dividing the signal coverage area of the Wi-Fi access point into at least two sections, wherein the coverage area is divided according to at least two radials and at least one distance from the Wi-Fi access point;
determining radio propagation characteristics for each section; and assigning a weight to each section based on the coverage areas of the Wi-Fi access points, where sections having relatively small coverage areas are assigned a higher effective weight than sections having relatively large coverage areas, wherein the location estimation will bias its estimate of position to rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.
determining the geographic location of the Wi-Fi access points; for each Wi-Fi access point, measuring a plurality of power values for signals transmitted by a corresponding Wi-Fi access point, each power value being measured at position relative to each corresponding Wi-Fi access point;
determining a signal coverage area of each Wi-Fi access point based on said measured plurality of power values;
dividing the signal coverage area of the Wi-Fi access point into at least two sections, wherein the coverage area is divided according to at least two radials and at least one distance from the Wi-Fi access point;
determining radio propagation characteristics for each section; and assigning a weight to each section based on the coverage areas of the Wi-Fi access points, where sections having relatively small coverage areas are assigned a higher effective weight than sections having relatively large coverage areas, wherein the location estimation will bias its estimate of position to rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.
2. The method of claim 1, wherein the sections are divided according to at least two radials from the Wi-Fi access point.
3. The method of claim 2, wherein the number of radials is six or less.
4. The method of claim 1, wherein the sections are divided according to at least one distance from the Wi-Fi access point.
5. The method of claim 4, wherein the number of distances is one.
6. The method of claim 1, wherein the radio propagation characteristics include a signal power-distance gradient.
7. The method of claim 6, wherein the signal power-distance gradient for each section is determined by a method comprising:
performing a linear regression on the plurality of power values and associated positions;
and using a slope determined by the linear regression to calculate the signal power-distance gradient.
performing a linear regression on the plurality of power values and associated positions;
and using a slope determined by the linear regression to calculate the signal power-distance gradient.
8. The method of claim 6, wherein the signal power-distance gradient for each section is determined by the method comprising:
calculating a distance corresponding to each of the power values, the distances being measured from the associated positions of the power values to the geographic locations of the Wi-Fi access points;
estimating a radius of signal coverage using the standard deviation of the distances; and using the radius of signal coverage to calculate the signal power-distance gradient.
calculating a distance corresponding to each of the power values, the distances being measured from the associated positions of the power values to the geographic locations of the Wi-Fi access points;
estimating a radius of signal coverage using the standard deviation of the distances; and using the radius of signal coverage to calculate the signal power-distance gradient.
9. The method of claim 8, wherein the standard deviation of the distances, a., is calculated according to equations having the feu in wherein:
d i is the distance of the associated position of received power value i from the location of the Wi-Fi access point; and N is the number of power values.
d i is the distance of the associated position of received power value i from the location of the Wi-Fi access point; and N is the number of power values.
10. The method of claim 8, wherein the signal power-distance gradient, a, is calculated using equations having the form wherein .sigma. min is a minimum signal coverage threshold;
.sigma. max is a maximum signal coverage threshold;
.sigma. is the average radius of signal coverage;
.alpha. min is a minimum signal power-distance gradient; and .alpha. max is a maximum signal power-distance gradient.
.sigma. max is a maximum signal coverage threshold;
.sigma. is the average radius of signal coverage;
.alpha. min is a minimum signal power-distance gradient; and .alpha. max is a maximum signal power-distance gradient.
11. The method of claim 10, wherein:
a five-sigma value of .sigma. min is about 60 meters;
a five-sigma value of .sigma. max is about 700 meters;
.alpha. min is 2 dBWatts / dBMeters; and .alpha. max is 6 dBWatts / dBMeters.
a five-sigma value of .sigma. min is about 60 meters;
a five-sigma value of .sigma. max is about 700 meters;
.alpha. min is 2 dBWatts / dBMeters; and .alpha. max is 6 dBWatts / dBMeters.
12. A method for estimating the position of a Wi-Fi enabled device using qualitative data related to one or more characteristics of a Wi-Fi access point's signal coverage area, the method comprising:
receiving one or more signals transmitted by the Wi-Fi access points;
identifying the Wi-Fi access points;
retrieving previously calculated locations of the Wi-Fi access points and previously calculated weights assigned to the Wi-Fi access points from a reference database, where the weights correspond to characteristics of each Wi-Fi access point's coverage area, including a plurality of measured power values for each access point, wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point and using the calculated locations and the calculated weights to estimate the position of the Wi-Fi enabled device, wherein Wi-Fi access points having relatively small coverage areas are assigned a higher effective weight than Wi-Fi access points having relatively large coverage areas and the position estimate of the Wi-Fi enabled device will be biased to rely more heavily rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.
receiving one or more signals transmitted by the Wi-Fi access points;
identifying the Wi-Fi access points;
retrieving previously calculated locations of the Wi-Fi access points and previously calculated weights assigned to the Wi-Fi access points from a reference database, where the weights correspond to characteristics of each Wi-Fi access point's coverage area, including a plurality of measured power values for each access point, wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point and using the calculated locations and the calculated weights to estimate the position of the Wi-Fi enabled device, wherein Wi-Fi access points having relatively small coverage areas are assigned a higher effective weight than Wi-Fi access points having relatively large coverage areas and the position estimate of the Wi-Fi enabled device will be biased to rely more heavily rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.
13. The method of claim 12, wherein at least one of the Wi-Fi access points has a radius of coverage, the radius of coverage having at least one section, each section having corresponding weights, where the weights correspond to characteristics of the Wi-Fi access point's coverage area.
14. A method of characterizing Wi-Fi access points in order to increase the accuracy of position, velocity and bearing estimation techniques based on signals received from those access points by classifying the Wi-Fi access points based on coverage areas of the Wi-Fi signals emitted by the Wi-Fi access points, the method of characterizing comprising:
measuring a series of Wi-Fi signals of each Wi-Fi access point;
determining a coverage area of each Wi-Fi access point based on its corresponding series of signals; wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point; and assigning a weight to each Wi-Fi access point based on the coverage areas in which Wi-Fi access points having relatively small coverage areas are assigned a higher effective weight than Wi-Fi access points having relatively large coverage areas, wherein position, velocity, and bearing estimation techniques will bias their estimates of position, velocity, and bearing to more heavily rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.
measuring a series of Wi-Fi signals of each Wi-Fi access point;
determining a coverage area of each Wi-Fi access point based on its corresponding series of signals; wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point; and assigning a weight to each Wi-Fi access point based on the coverage areas in which Wi-Fi access points having relatively small coverage areas are assigned a higher effective weight than Wi-Fi access points having relatively large coverage areas, wherein position, velocity, and bearing estimation techniques will bias their estimates of position, velocity, and bearing to more heavily rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.
15. The method of claim 14, wherein determining the coverage area comprises:
calculating a plurality of distances corresponding to each received signal within the coverage area of the Wi-Fi access point, the distances being measured from the associated position relative to the Wi-Fi access point; and determining an average radius of coverage of the Wi-Fi access point based on the plurality of distances from the access point.
calculating a plurality of distances corresponding to each received signal within the coverage area of the Wi-Fi access point, the distances being measured from the associated position relative to the Wi-Fi access point; and determining an average radius of coverage of the Wi-Fi access point based on the plurality of distances from the access point.
16. The method of claim 15, wherein determining the coverage area comprises:
determining the standard deviation of the coverage area in the Wi-Fi access point based on the plurality of distances.
determining the standard deviation of the coverage area in the Wi-Fi access point based on the plurality of distances.
17. The method of claim 15 further comprising:
determining a differential of a power value in dB of the received signal and the distance in dB from the Wi-Fi access point at each of the plurality of distances.
determining a differential of a power value in dB of the received signal and the distance in dB from the Wi-Fi access point at each of the plurality of distances.
18. The method of claim 14, wherein the weight of the Wi-Fi access point is assigned using a power-distance gradient of the Wi-Fi access point, wherein a larger power-distance gradient corresponds to a higher weight and a smaller power-distance gradient corresponds to a smaller weight.
19. The method of claim 14, further comprising:
dividing the coverage area into a plurality of sections based on the series of signals and assigning a weight to each of the plurality of sections, wherein the weight is used as a characteristic of the section in the position, velocity, and bearing estimation techniques.
dividing the coverage area into a plurality of sections based on the series of signals and assigning a weight to each of the plurality of sections, wherein the weight is used as a characteristic of the section in the position, velocity, and bearing estimation techniques.
20.
A method of characterizing Wi-Fi access points in order to increase the accuracy of position, velocity and bearing estimation techniques based on signals received from those access points by classifying the Wi-Fi access points based on coverage areas of the Wi-Fi signals emitted by the Wi-Fi access points, the method of characterizing comprising:
measuring a series of power values of the Wi-Fi signal of the Wi-Fi access point at a plurality of distances from the Wi-Fi access point;
determining a coverage area of the Wi-Fi access point based on the series of power values at the plurality of distances; and assigning a weight to the Wi-Fi access point based on the coverage area, wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point, wherein the weight of the Wi-Fi access point is assigned using the differential of the power in dB and the distance in dB from the Wi-Fi access point, wherein a larger differential corresponds to a higher weight and a smaller differential corresponds to a smaller weight, so that position, velocity, and bearing estimation techniques will bias their estimates position, velocity, and bearing to move heavily rely on signals detected from the Wi-Fi access points with a relatively larger differential.
A method of characterizing Wi-Fi access points in order to increase the accuracy of position, velocity and bearing estimation techniques based on signals received from those access points by classifying the Wi-Fi access points based on coverage areas of the Wi-Fi signals emitted by the Wi-Fi access points, the method of characterizing comprising:
measuring a series of power values of the Wi-Fi signal of the Wi-Fi access point at a plurality of distances from the Wi-Fi access point;
determining a coverage area of the Wi-Fi access point based on the series of power values at the plurality of distances; and assigning a weight to the Wi-Fi access point based on the coverage area, wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point, wherein the weight of the Wi-Fi access point is assigned using the differential of the power in dB and the distance in dB from the Wi-Fi access point, wherein a larger differential corresponds to a higher weight and a smaller differential corresponds to a smaller weight, so that position, velocity, and bearing estimation techniques will bias their estimates position, velocity, and bearing to move heavily rely on signals detected from the Wi-Fi access points with a relatively larger differential.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/430,222 | 2006-05-08 | ||
US11/430,222 US7515578B2 (en) | 2006-05-08 | 2006-05-08 | Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system |
PCT/US2007/068248 WO2007133967A2 (en) | 2006-05-08 | 2007-05-04 | Estimation of position using wlan access radio propagation characteristics in a wlan positioning system |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2651853A1 CA2651853A1 (en) | 2007-11-22 |
CA2651853C true CA2651853C (en) | 2015-06-23 |
Family
ID=38661106
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA2651853A Active CA2651853C (en) | 2006-05-08 | 2007-05-04 | Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system |
Country Status (7)
Country | Link |
---|---|
US (4) | US7515578B2 (en) |
EP (1) | EP2022278B1 (en) |
JP (1) | JP2009536808A (en) |
KR (1) | KR20090008465A (en) |
CA (1) | CA2651853C (en) |
ES (1) | ES2471127T3 (en) |
WO (1) | WO2007133967A2 (en) |
Families Citing this family (156)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
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 |
US8601606B2 (en) | 2002-11-25 | 2013-12-03 | Carolyn W. Hafeman | Computer recovery or return |
US7123928B2 (en) | 2003-07-21 | 2006-10-17 | Qualcomm Incorporated | Method and apparatus for creating and using a base station almanac for position determination |
US9137771B2 (en) | 2004-04-02 | 2015-09-15 | Qualcomm Incorporated | Methods and apparatuses for beacon assisted position determination systems |
US7403762B2 (en) * | 2004-10-29 | 2008-07-22 | Skyhook Wireless, Inc. | Method and system for building a location beacon database |
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 |
US7502620B2 (en) * | 2005-03-04 | 2009-03-10 | Shyhook Wireless, Inc. | Encoding and compression of a location beacon database |
KR101249178B1 (en) | 2005-02-22 | 2013-04-03 | 스카이후크 와이어리스, 인크. | Continuous data optimization in positioning system |
EP1911312B8 (en) * | 2005-07-25 | 2016-07-13 | Telefonaktiebolaget LM Ericsson (publ) | Means and methods for improving the handover characteristics of radio access networks |
US20070139199A1 (en) * | 2005-11-29 | 2007-06-21 | Pango Networks, Inc. | Method and apparatus for an active radio frequency identification tag |
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 |
US7835754B2 (en) | 2006-05-08 | 2010-11-16 | Skyhook Wireless, Inc. | Estimation of speed and direction of travel 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 |
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 |
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 |
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 |
WO2007146346A2 (en) * | 2006-06-13 | 2007-12-21 | Wms Gaming Inc. | Location detection for portable wagering game machines |
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 |
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 |
US7706811B2 (en) | 2006-09-19 | 2010-04-27 | Broadphone Llc | Signal comparison-based location determining method |
US7856234B2 (en) * | 2006-11-07 | 2010-12-21 | Skyhook Wireless, Inc. | System and method for estimating positioning error within a WLAN-based positioning system |
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 |
US8838477B2 (en) | 2011-06-09 | 2014-09-16 | Golba Llc | Method and system for communicating location of a mobile device for hands-free payment |
US8838481B2 (en) | 2011-07-26 | 2014-09-16 | Golba Llc | Method and system for location based hands-free payment |
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 |
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 |
GB0724063D0 (en) * | 2007-12-10 | 2008-01-23 | Vodafone Group Services Ltd | Femtocell location |
US9829560B2 (en) | 2008-03-31 | 2017-11-28 | Golba Llc | Determining the position of a mobile device using the characteristics of received signals and a reference database |
US7800541B2 (en) | 2008-03-31 | 2010-09-21 | Golba Llc | Methods and systems for determining the location of an electronic device |
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 |
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 |
US8212723B2 (en) * | 2008-08-27 | 2012-07-03 | Qualcomm Incorporated | Method and apparatus for determining at a predetermined granularity the direction and range of a transmitting mobile device |
KR101015648B1 (en) | 2008-10-15 | 2011-02-22 | 배세훈 | Geographic Information System based Wi-Fi WarDriving Hacking Protection System |
US8478228B2 (en) | 2008-10-20 | 2013-07-02 | Qualcomm Incorporated | Mobile receiver with location services capability |
US8108933B2 (en) | 2008-10-21 | 2012-01-31 | Lookout, Inc. | System and method for attack and malware prevention |
US9043919B2 (en) | 2008-10-21 | 2015-05-26 | Lookout, Inc. | Crawling multiple markets and correlating |
US8533844B2 (en) | 2008-10-21 | 2013-09-10 | Lookout, Inc. | System and method for security data collection and analysis |
US9235704B2 (en) | 2008-10-21 | 2016-01-12 | Lookout, Inc. | System and method for a scanning API |
US8087067B2 (en) | 2008-10-21 | 2011-12-27 | Lookout, Inc. | Secure mobile platform system |
US9781148B2 (en) | 2008-10-21 | 2017-10-03 | Lookout, Inc. | Methods and systems for sharing risk responses between collections of mobile communications devices |
US8060936B2 (en) | 2008-10-21 | 2011-11-15 | Lookout, Inc. | Security status and information display system |
US8984628B2 (en) | 2008-10-21 | 2015-03-17 | Lookout, Inc. | System and method for adverse mobile application identification |
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 |
US8051480B2 (en) | 2008-10-21 | 2011-11-01 | Lookout, Inc. | System and method for monitoring and analyzing multiple interfaces and multiple protocols |
US9042876B2 (en) | 2009-02-17 | 2015-05-26 | Lookout, Inc. | System and method for uploading location information based on device movement |
US8855601B2 (en) | 2009-02-17 | 2014-10-07 | Lookout, Inc. | System and method for remotely-initiated audio communication |
US8467768B2 (en) | 2009-02-17 | 2013-06-18 | Lookout, Inc. | System and method for remotely securing or recovering a mobile device |
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 |
US8538815B2 (en) | 2009-02-17 | 2013-09-17 | Lookout, Inc. | System and method for mobile device replacement |
US9119166B1 (en) | 2009-02-20 | 2015-08-25 | Babak Sheikh | Interpersonal communication and interactive information system |
US8639270B2 (en) | 2010-08-06 | 2014-01-28 | Golba Llc | Method and system for device positioning utilizing distributed transceivers with array processing |
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 |
US20110021207A1 (en) * | 2009-07-24 | 2011-01-27 | Morgan Edward J | System and Method for Estimating Positioning Error Within a WLAN-Based Positioning System |
US8600297B2 (en) | 2009-07-28 | 2013-12-03 | Qualcomm Incorporated | Method and system for femto cell self-timing and self-locating |
US8330605B2 (en) * | 2009-08-14 | 2012-12-11 | Accenture Global Services Limited | System for providing real time locating and gas exposure monitoring |
US8451120B2 (en) | 2009-08-14 | 2013-05-28 | Accenture Global Services Limited | System for relative positioning of access points in a real time locating system |
US8406785B2 (en) | 2009-08-18 | 2013-03-26 | 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 |
US20110080318A1 (en) * | 2009-10-02 | 2011-04-07 | Skyhook Wireless, Inc. | Determining A Dilution of Precision Metric Using Two or Three GPS Satellites |
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 |
US9165304B2 (en) | 2009-10-23 | 2015-10-20 | Service Management Group, Inc. | Analyzing consumer behavior using electronically-captured consumer location data |
JP5258865B2 (en) * | 2009-11-05 | 2013-08-07 | サムソン エスディーエス カンパニー リミテッド | Wireless device location tracking system and method using wireless LANAP |
US8397301B2 (en) | 2009-11-18 | 2013-03-12 | Lookout, Inc. | System and method for identifying and assessing vulnerabilities on a mobile communication device |
FR2954884B1 (en) * | 2009-12-24 | 2012-07-13 | Univ Compiegne Tech | METHOD, COMPUTER PROGRAM, AND DEVICE FOR RELATIVE ORIENTATION OF WIRELESS MOBILE TERMINALS |
NL2004070C2 (en) | 2010-01-07 | 2011-07-11 | Ambient Holding B V | Method for determining the location of a mobile device, mobile device and system for such method. |
US8433334B2 (en) | 2010-01-15 | 2013-04-30 | Apple Inc. | Managing a location database for network-based positioning system |
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 |
US8504059B2 (en) * | 2010-01-15 | 2013-08-06 | Apple Inc. | Location filtering using mobile country code |
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 |
US9131459B2 (en) * | 2010-02-01 | 2015-09-08 | Qualcomm Incorporated | Mobile station positioning assistance with local mapping data |
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 |
US8620344B2 (en) | 2010-04-07 | 2013-12-31 | Apple Inc. | Location-based application program management |
JP5249991B2 (en) | 2010-05-26 | 2013-07-31 | 株式会社エヌ・ティ・ティ・ドコモ | Positioning apparatus and method |
EP2580605B1 (en) | 2010-06-11 | 2016-05-04 | Skyhook Wireless, Inc. | Methods of and systems for measuring beacon stability of wireless access points |
US8816848B2 (en) | 2010-06-22 | 2014-08-26 | Sling Media, Inc. | Systems and methods for determining location from wireless signals |
WO2012011624A1 (en) * | 2010-07-21 | 2012-01-26 | (주)브이아이소프트 | System and method for indoor navigation based on a wi-fi radio map and utilizing user mobility in location estimation |
CN103119470B (en) * | 2010-07-21 | 2015-09-16 | 韩国贸易信息通信株式会社 | Carry out the system and method for the position-based service of indoor navigation |
US9638786B2 (en) | 2010-07-22 | 2017-05-02 | Mobixity, Inc. | System and method for locating a mobile terminal in a finite location |
DE102010032711A1 (en) | 2010-07-29 | 2012-02-02 | T-Mobile Austria Ges. M.B.H. | Method for determining location of mobile terminal, involves receiving radio signal from radio network by receiving component, and receiving another radio signal from another radio network by receiving component |
US8630640B2 (en) * | 2010-09-16 | 2014-01-14 | Qualcomm Incororated | Refining femtocell coverage information with beacon transmitters |
CN103120000B (en) * | 2010-09-23 | 2017-03-08 | 诺基亚技术有限公司 | The generation of overlay area model and use |
US8606294B2 (en) | 2010-10-05 | 2013-12-10 | Skyhook Wireless, Inc. | Method of and system for estimating temporal demographics of mobile users |
US8174931B2 (en) | 2010-10-08 | 2012-05-08 | HJ Laboratories, LLC | Apparatus and method for providing indoor location, position, or tracking of a mobile computer using building information |
EP2635915B1 (en) | 2010-11-03 | 2016-05-18 | Skyhook Wireless, Inc. | Method of system for increasing the reliability and accuracy of location estimation in a hybrid positioning system |
WO2012069686A1 (en) | 2010-11-24 | 2012-05-31 | Crambo, S.A. | Communication system and method involving the creation of virtual spaces |
US8553617B1 (en) | 2010-12-01 | 2013-10-08 | Google Inc. | Channel scanning |
US8594003B2 (en) * | 2011-01-05 | 2013-11-26 | Visoft Ltd. | Method of estimating location of mobile device in transportation using WiFi |
US8326260B1 (en) | 2011-05-18 | 2012-12-04 | Radius Networks, Inc. | System and method for managing communications over a wireless network during an emergency |
US8738765B2 (en) | 2011-06-14 | 2014-05-27 | Lookout, Inc. | Mobile device DNS optimization |
US20120331561A1 (en) | 2011-06-22 | 2012-12-27 | Broadstone Andrew J | Method of and Systems for Privacy Preserving Mobile Demographic Measurement of Individuals, Groups and Locations Over Time and Space |
WO2013003468A2 (en) | 2011-06-27 | 2013-01-03 | Cadio, Inc. | Triggering collection of information based on location data |
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 |
GB201116524D0 (en) * | 2011-09-23 | 2011-11-09 | Sensewhere Ltd | Method of estimating the position of a user device |
EP2584371B1 (en) | 2011-10-17 | 2016-12-21 | Commissariat à l'Énergie Atomique et aux Énergies Alternatives | Range estimation method based on RSS measurement with limited sensitivity receiver |
WO2013067526A1 (en) | 2011-11-04 | 2013-05-10 | Remote TelePointer, LLC | Method and system for user interface for interactive devices using a mobile device |
US8644852B2 (en) | 2011-11-10 | 2014-02-04 | Skyhook Wireless, Inc. | Method and system for capturing and providing typological and contextual information about a location based on wireless beacons |
US20130131972A1 (en) * | 2011-11-18 | 2013-05-23 | Microsoft Corporation | Computing-device localization based on inertial sensors |
WO2013084032A1 (en) * | 2011-12-09 | 2013-06-13 | Nokia Corporation | Positioning based on coverage area position information locally stored in a terminal |
US8611247B2 (en) * | 2012-01-24 | 2013-12-17 | Qualcomm Incorporated | Dynamic data retrieval in a WLAN positioning system |
CN102610000A (en) * | 2012-03-14 | 2012-07-25 | 江苏钱旺网络科技有限公司 | Employee attendance location method based on Wi-Fi (wireless fidelity) technology |
US9539164B2 (en) | 2012-03-20 | 2017-01-10 | Xerox Corporation | System for indoor guidance with mobility assistance |
US9279878B2 (en) | 2012-03-27 | 2016-03-08 | Microsoft Technology Licensing, Llc | Locating a mobile device |
US8862067B2 (en) * | 2012-03-27 | 2014-10-14 | Microsoft Corporation | Proximate beacon identification |
US8812023B2 (en) * | 2012-05-18 | 2014-08-19 | Qualcomm Incorporated | Outdoor position estimation of a mobile device within a vicinity of one or more indoor environments |
US9589129B2 (en) | 2012-06-05 | 2017-03-07 | Lookout, Inc. | Determining source of side-loaded software |
US9407443B2 (en) | 2012-06-05 | 2016-08-02 | Lookout, Inc. | Component analysis of software applications on computing devices |
EP2873293B1 (en) * | 2012-07-11 | 2016-09-21 | Empire Technology Development LLC | Schemes for providing private wireless network |
US9064265B1 (en) | 2012-08-29 | 2015-06-23 | Babak Sheikh | System and method for locating items in a facility |
CN102841047B (en) * | 2012-08-31 | 2015-07-01 | 深圳市华星光电技术有限公司 | Cleanness monitoring system and cassette |
US9448298B2 (en) * | 2012-09-28 | 2016-09-20 | Qualcomm Incorporated | Techniques for faster time-to-first-fix |
GB201506927D0 (en) | 2012-10-01 | 2015-06-10 | Service Man Group Inc | Consumer analytics system that determines, offers, and monitors use of rewards incentivizing consumers to perform tasks |
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 |
US9612121B2 (en) | 2012-12-06 | 2017-04-04 | Microsoft Technology Licensing, Llc | Locating position within enclosure |
US9208215B2 (en) | 2012-12-27 | 2015-12-08 | Lookout, Inc. | User classification based on data gathered from a computing device |
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 |
CN103079269A (en) * | 2013-01-25 | 2013-05-01 | 哈尔滨工业大学 | LDE (Linear Discriminant Analysis) algorithm-based WiFi (Wireless Fidelity) indoor locating method |
CN103200670B (en) * | 2013-02-25 | 2015-08-05 | 北京科技大学 | The cognitive radio primary user localization method of convex set projection is checked based on backtracking |
KR20140118667A (en) | 2013-03-29 | 2014-10-08 | 삼성전자주식회사 | Display apparatus and control method thereof |
US20140355465A1 (en) * | 2013-05-31 | 2014-12-04 | Broadcom Corporation | Device Locationing Using Wireless Communication |
GB2516848B8 (en) * | 2013-08-01 | 2020-11-18 | Here Global Bv | Assigning location information to wireless local area network access points |
US9277483B2 (en) * | 2013-09-27 | 2016-03-01 | Verizon Patent And Licensing Inc. | User geo-location pattern analysis |
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 |
US9521568B2 (en) * | 2013-11-19 | 2016-12-13 | Marvell World Trade Ltd. | Wireless LAN device positioning |
US10122747B2 (en) | 2013-12-06 | 2018-11-06 | Lookout, Inc. | Response generation after distributed monitoring and evaluation of multiple devices |
US9753796B2 (en) | 2013-12-06 | 2017-09-05 | Lookout, Inc. | Distributed monitoring, evaluation, and response for multiple devices |
US9661465B2 (en) | 2013-12-27 | 2017-05-23 | Empire Technology Development Llc | Location determining scheme |
US10057717B2 (en) | 2013-12-27 | 2018-08-21 | Empire Technology Development Llc | Location determining scheme |
CN105850081B (en) | 2013-12-31 | 2019-10-08 | 红点定位公司 | Estimate the method and system of the position of the sending device in (asynchronous) wireless network |
CN103648106B (en) * | 2013-12-31 | 2017-03-22 | 哈尔滨工业大学 | WiFi indoor positioning method of semi-supervised manifold learning based on category matching |
US9674656B2 (en) * | 2014-02-20 | 2017-06-06 | Microsoft Technology Licensing, Llc | Wireless-based localization using a zonal framework |
KR101867745B1 (en) * | 2014-03-28 | 2018-06-14 | 인텔 아이피 코포레이션 | 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 |
JP6326646B2 (en) * | 2014-08-28 | 2018-05-23 | 株式会社国際電気通信基礎技術研究所 | Attenuation characteristic function estimation device, attenuation characteristic function estimation method, and program |
FR3025641B1 (en) * | 2014-09-08 | 2016-12-23 | Valeo Comfort & Driving Assistance | METHOD FOR DETECTING AN IDENTIFIER FOR STARTING A MOTOR VEHICLE |
EP3289510B1 (en) | 2015-05-01 | 2020-06-17 | Lookout Inc. | Determining source of side-loaded software |
CN105227361B (en) * | 2015-09-30 | 2018-11-02 | 百度在线网络技术(北京)有限公司 | Information acquisition method and device |
JP2016145836A (en) * | 2016-03-23 | 2016-08-12 | インテル コーポレイション | Mechanism for employing and realizing geodetic triangulation for determining global positioning of computing devices |
US10454599B2 (en) * | 2016-04-05 | 2019-10-22 | Bit Lion, LLC | System for visualization of electromagnetic wave distribution and collaborative web-based design for optimal distribution of emitters |
EP3465273A4 (en) | 2016-05-24 | 2020-01-15 | Topcon Positioning Systems, Inc. | Position determination of a mobile station using modified wi-fi signals |
US9635510B1 (en) | 2016-06-24 | 2017-04-25 | Athentek Innovations, Inc. | Database for Wi-Fi position estimation |
CN106443649A (en) * | 2016-08-31 | 2017-02-22 | 成都中星世通电子科技有限公司 | Single directional detection station location method |
US10218697B2 (en) | 2017-06-09 | 2019-02-26 | Lookout, Inc. | Use of device risk evaluation to manage access to services |
JP6810673B2 (en) * | 2017-11-02 | 2021-01-06 | 日本電信電話株式会社 | Equipment and programs for positioning |
US11622234B2 (en) | 2019-09-13 | 2023-04-04 | Troverlo, Inc. | Passive asset tracking using observations of Wi-Fi access points |
US11589187B2 (en) | 2019-09-13 | 2023-02-21 | Troverlo, Inc. | Passive sensor 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 |
US11265677B2 (en) * | 2019-12-24 | 2022-03-01 | Gunitech Corp. | Power positioning method and power positioning device thereof |
US11805389B2 (en) * | 2020-10-27 | 2023-10-31 | International Business Machines Corporation | Evaluation of device placement |
US20220283258A1 (en) * | 2021-03-04 | 2022-09-08 | Cisco Technology, Inc. | Hybrid ranging |
Family Cites Families (70)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0974585A (en) * | 1995-09-06 | 1997-03-18 | Nippon Motorola Ltd | Location detector for mobile station |
KR100272431B1 (en) * | 1998-09-03 | 2000-11-15 | 김영환 | Device for expanding coverage of cdma mobile communication system and method thereof |
US7164725B2 (en) * | 2000-03-10 | 2007-01-16 | Motorola, Inc. | Method and apparatus for antenna array beamforming |
US6711404B1 (en) * | 2000-07-21 | 2004-03-23 | Scoreboard, Inc. | Apparatus and method for geostatistical analysis of wireless signal propagation |
US6748742B2 (en) * | 2000-11-07 | 2004-06-15 | Capstone Turbine Corporation | Microturbine combination systems |
US7076225B2 (en) * | 2001-02-16 | 2006-07-11 | Qualcomm Incorporated | Variable gain selection in direct conversion receiver |
JP4349758B2 (en) * | 2001-03-27 | 2009-10-21 | パイオニア株式会社 | Positioning device |
US6888811B2 (en) * | 2001-09-24 | 2005-05-03 | Motorola, Inc. | Communication system for location sensitive information and method therefor |
US20030118015A1 (en) * | 2001-12-20 | 2003-06-26 | Magnus Gunnarsson | Location based notification of wlan availability via wireless communication network |
US6664925B1 (en) * | 2002-05-02 | 2003-12-16 | Microsoft Corporation | Method and system for determining the location of a mobile computer |
JP2003329757A (en) | 2002-05-13 | 2003-11-19 | Hitachi Ltd | Radio method and apparatus for measuring position |
FI113092B (en) | 2002-05-31 | 2004-02-27 | Ekahau Oy | Measures of position differences and applications |
US6865395B2 (en) * | 2002-08-08 | 2005-03-08 | Qualcomm Inc. | Area based position determination for terminals in a wireless network |
US20040057408A1 (en) * | 2002-09-19 | 2004-03-25 | Gray William H. | Method and system of providing bandwidth on demand to WAN user from WLAN access point |
JP3829784B2 (en) * | 2002-09-19 | 2006-10-04 | 日本電信電話株式会社 | POSITION DETECTION METHOD AND SYSTEM AND RADIO COMMUNICATION DEVICE |
US8116285B1 (en) * | 2002-09-19 | 2012-02-14 | Hewlett-Packard Development Company, L.P. | Intelligent wireless access point selection |
US7660588B2 (en) * | 2002-10-17 | 2010-02-09 | Qualcomm Incorporated | Method and apparatus for improving radio location accuracy with measurements |
US7369859B2 (en) * | 2003-10-17 | 2008-05-06 | Kineto Wireless, Inc. | Method and system for determining the location of an unlicensed mobile access subscriber |
US7136655B2 (en) * | 2002-11-21 | 2006-11-14 | Bandspeed, Inc. | Method and apparatus for coverage and throughput enhancement in a wireless communication system |
US7257411B2 (en) * | 2002-12-27 | 2007-08-14 | Ntt Docomo, Inc. | Selective fusion location estimation (SELFLOC) for wireless access technologies |
WO2004073243A2 (en) * | 2003-02-13 | 2004-08-26 | Wavelink Corporation | Channel, coding and power management for wireless local area networks |
US8971913B2 (en) * | 2003-06-27 | 2015-03-03 | Qualcomm Incorporated | Method and apparatus for wireless network hybrid 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 |
GB2405276B (en) * | 2003-08-21 | 2005-10-12 | Motorola Inc | Measuring distance using wireless communication |
US20050073980A1 (en) * | 2003-09-17 | 2005-04-07 | Trapeze Networks, Inc. | Wireless LAN management |
US7904244B2 (en) * | 2003-11-18 | 2011-03-08 | Sarimo Technologies, LLC | Determining a location or position using information from multiple location and positioning technologies and applications using such a determined location or position |
US7433696B2 (en) * | 2004-05-18 | 2008-10-07 | Cisco Systems, Inc. | Wireless node location mechanism featuring definition of search region to optimize location computation |
EP1759222A1 (en) | 2004-06-09 | 2007-03-07 | Philips Intellectual Property & Standards GmbH | Automatic generation of signal strength map for location determination of mobile devices |
US7319878B2 (en) * | 2004-06-18 | 2008-01-15 | Qualcomm Incorporated | Method and apparatus for determining location of a base station using a plurality of mobile stations in a wireless mobile network |
US7509131B2 (en) | 2004-06-29 | 2009-03-24 | Microsoft Corporation | Proximity detection using wireless signal strengths |
WO2006026679A1 (en) * | 2004-08-31 | 2006-03-09 | At & T Corp. | Method and system for assigning channels in a wireless lan |
US7403762B2 (en) * | 2004-10-29 | 2008-07-22 | Skyhook Wireless, Inc. | Method and system for building a location beacon database |
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 |
JP4302617B2 (en) * | 2004-12-13 | 2009-07-29 | インターナショナル・ビジネス・マシーンズ・コーポレーション | Wireless station |
EP1832138A1 (en) | 2004-12-27 | 2007-09-12 | MYTILINAIOS, A. Stylianos | Position location via geometric loci construction |
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 |
US7696923B2 (en) * | 2005-02-03 | 2010-04-13 | Mexens Intellectual Property Holding Llc | System and method for determining geographic location of wireless computing devices |
US7502620B2 (en) * | 2005-03-04 | 2009-03-10 | Shyhook Wireless, Inc. | Encoding and compression of a location beacon database |
KR101249178B1 (en) * | 2005-02-22 | 2013-04-03 | 스카이후크 와이어리스, 인크. | Continuous data optimization in positioning system |
US20060229088A1 (en) * | 2005-04-12 | 2006-10-12 | Sbc Knowledge Ventures L.P. | Voice broadcast location system |
CN101208974B (en) | 2005-05-04 | 2012-09-12 | 意大利电信股份公司 | Method for optimizing channel scanning function in telecommunication network of mobile terminal |
JP4568641B2 (en) * | 2005-05-27 | 2010-10-27 | 株式会社日立製作所 | Wireless communication system, node position calculation method, and node |
US7271764B2 (en) * | 2005-06-30 | 2007-09-18 | Intel Corporation | Time of arrival estimation mechanism |
RU2390791C2 (en) * | 2005-11-07 | 2010-05-27 | Квэлкомм Инкорпорейтед | Positioning for wlan and other wireless networks |
US20070150516A1 (en) * | 2005-11-23 | 2007-06-28 | Morgan Edward J | Location toolbar for internet search and communication |
US20070151516A1 (en) * | 2006-01-03 | 2007-07-05 | Law Kam S | Chemical vapor deposition apparatus and electrode plate thereof |
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 |
US7835754B2 (en) | 2006-05-08 | 2010-11-16 | Skyhook Wireless, Inc. | Estimation of speed and direction of travel in a WLAN positioning system |
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 |
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 |
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 |
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 |
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 |
US7856234B2 (en) | 2006-11-07 | 2010-12-21 | Skyhook Wireless, Inc. | System and method for estimating positioning error within a WLAN-based 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 |
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 |
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 |
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 |
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 |
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 |
US8638256B2 (en) * | 2009-09-29 | 2014-01-28 | Skyhook Wireless, Inc. | Accuracy and performance of a hybrid positioning system |
US20110080318A1 (en) * | 2009-10-02 | 2011-04-07 | Skyhook Wireless, Inc. | Determining A Dilution of Precision Metric Using Two or Three GPS Satellites |
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 |
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 |
EP2580605B1 (en) * | 2010-06-11 | 2016-05-04 | 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 |
EP2635915B1 (en) | 2010-11-03 | 2016-05-18 | Skyhook Wireless, Inc. | Method of system for increasing the reliability and accuracy of location estimation in a hybrid positioning system |
-
2006
- 2006-05-08 US US11/430,222 patent/US7515578B2/en active Active
-
2007
- 2007-05-04 EP EP07783288.9A patent/EP2022278B1/en active Active
- 2007-05-04 ES ES07783288.9T patent/ES2471127T3/en active Active
- 2007-05-04 JP JP2009510097A patent/JP2009536808A/en active Pending
- 2007-05-04 WO PCT/US2007/068248 patent/WO2007133967A2/en active Application Filing
- 2007-05-04 KR KR1020087029897A patent/KR20090008465A/en not_active Application Discontinuation
- 2007-05-04 CA CA2651853A patent/CA2651853C/en active Active
-
2009
- 2009-02-25 US US12/392,621 patent/US7916661B2/en active Active
-
2011
- 2011-03-14 US US13/047,253 patent/US8155673B2/en active Active
-
2012
- 2012-04-10 US US13/443,482 patent/US9052378B2/en active Active
Also Published As
Publication number | Publication date |
---|---|
US7515578B2 (en) | 2009-04-07 |
US8155673B2 (en) | 2012-04-10 |
WO2007133967A2 (en) | 2007-11-22 |
JP2009536808A (en) | 2009-10-15 |
EP2022278A4 (en) | 2010-07-14 |
WO2007133967A3 (en) | 2008-11-06 |
ES2471127T3 (en) | 2014-06-25 |
US20070258421A1 (en) | 2007-11-08 |
KR20090008465A (en) | 2009-01-21 |
US9052378B2 (en) | 2015-06-09 |
EP2022278B1 (en) | 2014-05-07 |
CA2651853A1 (en) | 2007-11-22 |
US20090154371A1 (en) | 2009-06-18 |
US20120196621A1 (en) | 2012-08-02 |
US20110164522A1 (en) | 2011-07-07 |
US7916661B2 (en) | 2011-03-29 |
EP2022278A2 (en) | 2009-02-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2651853C (en) | Estimation of position using wlan access point radio propagation characteristics in a wlan positioning system | |
US9955358B2 (en) | Determining quality metrics utilized in building a reference database | |
US10284997B2 (en) | System and method for estimating positioning error within a WLAN-based positioning system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request |