# US 9,521,568 B2 · Wireless LAN device positioning > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,521,568 B2 - Document ID: US9521568B2 - Status: Granted - Kind: B2 - Application number: 14/536,926 - Filed: 2014-11-10 - Published: 2015-05-21 - Granted: 2016-12-13 - Earliest claimed: 2013-11-19 - Assignees: Marvell World Trade Ltd. - Applicants: Marvell World Trade Ltd. - Inventors: BoChih Liu; Zhike Jia; Jing Yu; Jian Chen; Yuan Ren - Web page: https://patentgrep.com/patent/US9521568B2 ## CPC - H04W 24/08: Testing, {supervising or monitoring} using real traffic - G01S 5/02521: {using a radio-map} - G01S 5/02524: {Creating or updating the radio-map} - H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management - H04W 84/12: WLAN [Wireless Local Area Networks] - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - 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 A system and method to determine a location of a device in a wireless local area network (LAN) based on positioning assistance data acquired from a server is disclosed. The host-offload wireless LAN device may determine a location based on the location computations done inside the wireless LAN module. The device includes a storage medium configured to provide a database of positioning assistance data, a wireless LAN module configured to receive beacon signals broadcast from one or more access points, and a processor configured to store the access point identification information and the signal strength detected by the wireless LAN module in a first memory section, access the previously-stored positioning assistance data from the storage medium, assemble positioning assistance data based on a comparison, store the assembled positioning assistance data in a second memory section, and determine a location of wireless LAN device using assembled positioning assistance data. ## Claims ### Claim 1 A system for determining a location of a wireless local area network (LAN) device, the system comprising: a server, comprising: a storage medium configured to provide a database of location data, each location data associating position information of a location with an access point identification information for providing wireless communication at the location and strength of a signal received at the location; and a processor configured to: determine access point location-related parameters using a group of location data; check whether location-related conditions are satisfied for determining positioning assistance data; identify, when the location-related conditions are satisfied, a specific access point using the access point identification information to retrieve the group of location data from the database; determine the positioning assistance data using the group of location data; store the positioning assistance data; transmit the positioning assistance data to one or more wireless LAN devices; a wireless LAN device comprising: a storage medium configured to provide a database of the positioning assistance data, each positioning assistance data associating an access point identification information with an access point location, one or more polynomial coefficients, and a workable range of signal strength; a wireless LAN module configured to receive beacon signals broadcast from one or more access points that receives identifiers and strengths of signals from one or more access points; and a processor configured to: store the access point identification information and the signal strength detected by the wireless LAN module in a first memory section; access the previously-stored positioning assistance data from the storage medium; assemble positioning assistance data based on a comparison; store the assembled positioning assistance data in a second memory section; and determine a location of wireless LAN device using assembled positioning assistance data. ### Claim 2 (depends on 1) The system of claim 1, wherein the processor determines the access point location-related parameters, comprising: determine an estimated location of an access point; determine an estimated uncertainty associated with the estimated location of the access point; and determine a coverage area length for the access point. ### Claim 3 (depends on 2) The system of claim 2, wherein the location-related conditions are satisfied when the number of the group of the location data exceeds a predefined threshold, the estimated uncertainty is less than a predefined threshold, and the coverage area length is less than a predefined threshold. ### Claim 4 (depends on 1) The system of claim 1, wherein the processor determines the positioning assistance data based on strengths of the signals in the group of location data, comprising: determine one or more polynomial coefficients through a least squares fit; in response to determining polynomial coefficients, determine a workable range of the signal strength by analyzing the distribution of strength of the signals to associate a probability 0.95. ### Claim 5 (depends on 1) The system of claim 1, wherein the previously-stored positioning assistance data is stored in association with known geographic regions. ### Claim 6 (depends on 1) The system of claim 1, wherein the processor assemble positioning assistance data by comparing the detected access point identification information to previously-stored access point identification information included in previously-stored positioning assistance data, each assembled positioning assistance data associating an access point identification information with an access point location, one or more polynomial coefficients, a workable range of signal strength, and a detected signal strength. ### Claim 7 (depends on 1) The system of claim 1, wherein the processor determines a location of wireless LAN device, comprising: determine whether the detected signal strength is within the workable range of the signal strength in order to identify each of the assembled positioning assistance data that can be used for location determination; once identified, estimate a distance between wireless LAN device and the identified access point using the determined polynomial coefficients; and determine whether the number of determined distances exceeds a threshold value. ### Claim 8 (depends on 7) The system of claim 7, further comprising: determine a location based on iteratively estimating method using the locations of identified access points and the determined distances when the number of determined distances exceeds a threshold value. ### Claim 9 (depends on 7) The system of claim 7, further comprising: determine a location based on average method using the locations of identified access points when the number of determined distances does not exceed a threshold value. ### Claim 10 A method for determining a location of a wireless LAN device, the method comprising: providing, by a storage medium coupled to a server, a database of location data, each location data associating position information of a location with an access point identification information for providing wireless communication at the location and strength of a signal received at the location; determining access point location-related parameters using a group of location data; checking whether location-related conditions are satisfied for determining positioning assistance data; identifying, when the location-related conditions are satisfied, a specific access point using the access point identification information to retrieve the group of location data from the database; determining the positioning assistance data using the group of location data; storing the positioning assistance data; transmitting the positioning assistance data to one or more wireless LAN devices; providing, a storage medium coupled to a wireless LAN device, a database of the positioning assistance data, each positioning assistance data associating an access point identification information with an access point location, one or more polynomial coefficients, and a workable range of signal strength; receiving, by a wireless LAN module coupled to a wireless LAN device, beacon signals broadcast from one or more access points that receives identifiers and strengths of the signals from one or more access points; storing the access point identification information and the signal strength detected by the wireless LAN module in a first memory section; accessing the previously-stored positioning assistance data from the storage medium; assembling positioning assistance data based on a comparison; storing the assembled positioning assistance data in a second memory section; and determining a location of wireless LAN device using assembled positioning assistance data. ### Claim 11 (depends on 10) The method of claim 10, wherein determining the access point location-related parameters, comprising: determining an estimated location of an access point; determining an estimated uncertainty associated with the estimated location of the access point; and determining a coverage area length for the access point. ### Claim 12 (depends on 11) The method of claim 11, wherein the location-related conditions are satisfied when the number of the group of the location data exceeds a predefined threshold, the estimated uncertainty is less than a predefined threshold, and the coverage area length is less than a predefined threshold. ### Claim 13 (depends on 10) The method of claim 10, wherein determining the positioning assistance data based on the strengths of the signals in the group of location data, comprising: determining one or more polynomial coefficients through a least squares fit; in response to determining polynomial coefficients, determining a workable range of the signal strength by analyzing the distribution of strength of the signals to associate a probability 0.95. ### Claim 14 (depends on 10) The method of claim 10, wherein the previously-stored positioning assistance data is stored in association with known geographic regions. ### Claim 15 (depends on 10) The method of claim 10, wherein assembling positioning assistance data by comparing the detected access point identification information to previously-stored access point identification information included in previously-stored positioning assistance data, each assembled positioning assistance data associating an access point identification information with an access point location, one or more polynomial coefficients, a workable range of signal strength, and a detected signal strength. ### Claim 16 (depends on 10) The method of claim 10, wherein determining a location of wireless LAN device, comprising: determining whether the detected signal strength is within the workable range of the signal strength in order to identify each of the assembled positioning assistance data that can be used for location determination; once identified, estimating a distance between wireless LAN device and the identified access point using the determined polynomial coefficients; and determining whether the number of determined distances exceeds a threshold value. ### Claim 17 (depends on 16) The method of claim 16, further comprising: determining a location based on iteratively estimating method using the locations of identified access points and the determined distances when the number of determined distances exceeds a threshold value. ### Claim 18 (depends on 16) The method of claim 16, further comprising: determining a location based on average method using the locations of identified access points when the number of determined distances does not exceed a threshold value. ### Claim 19 A method performed by a positioning server for use with access points through which mobile devices wirelessly communicate with a network, the method comprising: receiving data sets from the mobile devices, each data set including (i) a location of a respective one of the wireless devices, (ii) an identification of an access point from which the respective wireless device receives a signal, and (iii) a signal strength of the received signal; estimating, from the data sets, a location for each access point; determining, from the data sets, for each access point, a coefficient for an equation for calculating distance from the access point's estimated location as a function of signal strength; selecting access points from among the access points; transmitting, to a mobile device from among the mobile devices, the coefficient for each selected access point, for the mobile device to use the coefficient, along with the equation and received signal strengths from the selected access points, to estimate a location of the mobile device. ### Claim 20 (depends on 19) The method of claim 19, wherein the location in each data set is determined by the respective mobile device through satellite positioning, and the use of the coefficients by the mobile device includes triangulation.