# US 10,375,517 B2 · Crowd sourced pathway maps > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,375,517 B2 - Document ID: US10375517B2 - Status: Granted - Kind: B2 - Application number: 13/791,508 - Filed: 2013-03-08 - Published: 2014-09-11 - Granted: 2019-08-06 - Earliest claimed: 2013-03-08 - Assignees: Microsoft Technology Licensing, LLC - Applicants: Microsoft Technology Licensing, LLC - Inventors: Guobin (Jacky) Shen; Yongguang Zhang; Thomas Moscibroda - Web page: https://patentgrep.com/patent/US10375517B2 ## CPC - H04W 4/023: {using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds} - G01C 21/1654: {with electromagnetic compass} - G01C 21/206: {specially adapted for indoor navigation} - G01S 5/0263: {by combining or switching between positions derived from two or more separate positioning systems} - G01S 5/14: Determining absolute distances from a plurality of spaced points of known location - G01S 11/06: using intensity measurements - H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) - 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 ## Abstract Some implementations include identifying a location for a device perceived landmark. The location is identified by monitoring received signal strength of a signal of a wireless access point, detecting the location at which the trend in the received signal strength changes direction, and qualifying the location based on measurements taken form one or more inertial measurement unit sensors. ## Claims ### Claim 1 One or more computer storage media comprising instructions which, when executed by one or more processors, cause the one or more processors to: receive, from a mobile device, data related to a received signal strength of a signal from a wireless access point; receive, from the mobile device, a plurality of inertial measurements; monitor a trend of the received signal strength, wherein the trend of the received signal strength indicates that the received signal strength is increasing or decreasing; determine that the trend of the received signal strength switches either from increasing to decreasing or from decreasing to increasing; identify, based at least in part on the determination that the trend of the received signal strength has switched, a location as a perceivable landmark; and based at least in part on identifying the location, perform a perceivable landmark qualification process by: determining that the location is a qualified landmark based at least in part on the plurality of inertial measurements indicating a stable motion, or determining that the location is not a qualified landmark based at least in part on the plurality of inertial measurements indicating an unstable motion. ### Claim 2 (depends on 1) The one or more computer storage media as recited in claim 1, further comprising instructions which, when executed by one or more processors, cause the one or more processors to: detect a maximum received signal strength based at least in part on the determination that the trend of the received signal strength switches from increasing to decreasing; or detect a minimum received signal strength based at least in part on the determination that the trend of the received signal strength switches from decreasing to increasing. ### Claim 3 (depends on 1) The one or more computer storage media as recited in claim 1, further comprising instructions which when executed by one or more processors, cause the one or more processors to: cluster a plurality of qualified landmarks to generate a landmark set, the landmark set including a displacement measurement between individual pairs of qualified landmarks of the landmark set and a coordinate for individual qualified landmarks of the landmark set; and generate a map based at least in part on the landmark set. ### Claim 4 (depends on 3) The one or more computer storage media as recited in claim 3, further comprising instructions which, when executed by the one or more processors, cause the one or more processors to: receive trajectories from the mobile device; partition the trajectories into segments based on the landmark set, each segment including a plurality of pixels; weight the plurality of pixels of each segment; overlay the plurality of pixels of each segment onto the map; sum the weight of overlapping pixels; and remove pixels from the map if the summed weight is less than a threshold. ### Claim 5 (depends on 3) The one or more computer storage media as recited in claim 3, further comprising instructions which, when executed by the one or more processors, cause the one or more processors to cluster the plurality of qualified landmarks to generate the landmark set by: classifying the individual qualified landmarks of the landmark set into groups based at least in part on a master wireless access point associated with the individual qualified landmarks of the landmark set; classifying the plurality of qualified landmarks of the landmark set into sub-groups based at least in part on a direction of travel determined from the plurality of inertial measurements; calculating a distance between one or more pairs of qualified landmarks within the sub-group; and clustering a pair of qualified landmarks if the distance between the pair of qualified landmarks is less than a threshold. ### Claim 6 (depends on 1) The one or more computer storage media as recited in claim 1, wherein: the stable motion includes at least one of a straight line or a turning of a corner; and the unstable motion includes at least one of a u-turn or a zigzag motion. ### Claim 7 (depends on 1) The one or more computer storage media as recited in claim 1, wherein: the plurality of inertial measurements include: a first set of inertial measurements received from the mobile device before the switching of the trend; and a second set of inertial measurements received from the mobile device after the switching of the trend; and the perceivable landmark qualification process includes comparing the first set of inertial measurements to the second set of inertial measurements. ### Claim 8 A method comprising: identifying, by a mobile device, a signal of a wireless access point; monitoring a received signal strength of the signal; monitoring a trend of the received signal strength, wherein the trend of the received signal strength indicates that the received signal strength is increasing; detecting a location at which the received signal strength is at a maximum based at least in part on the trend of the received signal strength switching from the increasing in strength to decreasing in strength; identifying the location as a landmark; and performing a landmark qualification process for the landmark based at least in part on inertial measurements received from the mobile device while the signal strength was increasing and inertial measurements received from the mobile device while the signal strength was decreasing. ### Claim 9 (depends on 8) The method as recited in claim 8, wherein the monitoring the received signal strength is performed while the mobile device is in motion. ### Claim 10 (depends on 8) The method as recited in claim 8, further comprising providing, by the mobile device, data related to the landmark to a remote system via one or more communication interfaces. ### Claim 11 (depends on 8) The method as recited in claim 8, wherein performing the perceivable landmark qualification process comprises determining that the landmark is a qualified landmark based at least in part on a comparison of the inertial measurements received while the signal strength was increasing to the inertial measurements received while the signal strength was decreasing indicating a stable motion. ### Claim 12 (depends on 8) The method as recited in claim 8, wherein performing the perceivable landmark qualification process comprises determining that the landmark is not a qualified landmark based at least in part on a comparison of the inertial measurements received while the signal strength was increasing to the inertial measurements received while the signal strength was decreasing indicating an unstable motion. ### Claim 13 A device comprising: one or more communication interfaces for receiving a signal from a wireless access point; one or more inertial measurement unit (IMU) sensors to collect data related to movement of the device; one or more processors; and one or more computer-readable storage media storing instructions which, when executed by the one or more processors, cause the one or more processors to perform operations comprising: monitoring a trend of a received signal strength of the signal to identify a perceivable landmark, the perceivable landmark corresponding to a location at which the trend of the received signal strength changes either from increasing in strength to decreasing in strength or from decreasing in strength to increasing in strength while the data related to the movement of the device indicates the device is in motion; and based at least in part on identifying the perceivable landmark, performing a perceivable landmark qualification process to determine whether the perceivable landmark is a qualified landmark. ### Claim 14 (depends on 13) The device as recited in claim 13, wherein the one or more IMU sensors comprise at least one of an accelerometer, a gyroscope or a magnetometer. ### Claim 15 (depends on 13) The device as recited in claim 13, wherein the operations further comprise providing data related to the qualified landmark to a remote system via the one or more communication interfaces. ### Claim 16 (depends on 15) The device as recited in claim 15, wherein the operations further comprise receiving data related to a location-based service. ### Claim 17 (depends on 13) The device as recited in claim 13, wherein the operations further comprise detecting at least one of: a maximum received signal strength based at least in part on the trend of the received signal strength changing directions from increasing in strength to decreasing in strength; or a minimum received signal strength based at least in part on the trend of the received signal strength changing directions from decreasing in strength to increasing in strength. ### Claim 18 (depends on 13) The device as recited in claim 13, wherein performing the perceivable landmark qualification process includes determining whether the perceivable landmark is a qualified landmark based at least in part on the data related to the movement of the device. ### Claim 19 (depends on 13) The device as recited in claim 13, wherein performing the perceivable landmark qualification process includes determining that the perceivable landmark is a qualified landmark based at least in part on the data related to the movement of the device indicating a stable motion. ### Claim 20 (depends on 13) The device as recited in claim 13, wherein performing the perceivable landmark qualification process includes determining that the perceivable landmark is not a qualified landmark based at least in part on the data related to the movement of the device indicating an unstable motion.