# US 11,079,484 B2 · Communication device and a method for localization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,484 B2 - Document ID: US11079484B2 - Status: Granted - Kind: B2 - Application number: 16/304,148 - Filed: 2016-06-22 - Published: 2019-11-14 - Granted: 2021-08-03 - Earliest claimed: 2016-06-22 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Mi Sun Park; Lei Yang; Scott Thomas; Jung Woo; Addicam Sanjay - Web page: https://patentgrep.com/patent/US11079484B2 ## CPC - G01S 13/74: Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems - G01S 13/84: for distance determination by phase measurement - G01S 13/82: wherein continuous-type signals are transmitted - G06K 7/10366: {the interrogation device being adapted for miscellaneous applications} - G06K 19/0723: {the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs} - H04B 1/7156: Arrangements for sequence synchronisation - H04W 4/023: {using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds} - H04W 4/80: Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication - H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management - G01S 5/14: Determining absolute distances from a plurality of spaced points of known location - H04B 2001/71563: {Acquisition} - 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 - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A method for localizing a device. The method is performed by a communication device. The method includes measuring a phase of a signal that the communication device has received from the device, the signal having a first frequency; measuring a phase of at least one further signal that the communication device has received from the device; the at least one further signal having a second frequency, determining a phase pattern of a measured phase versus frequency, pattern matching the phase pattern with each reference phase pattern of a plurality of pre-determined reference phase patterns. Each reference phase pattern is associated with a distance between the communication device and the further communication device. The method further includes determining the distance between the further communication device and the communication device based on the pattern matching. ## Claims ### Claim 1 A method for localizing a device, the method performed in a communication device, the method comprising: measuring a phase of a first signal received by the communication device from the device, the first signal having a first frequency; measuring a phase of a second signal received by the communication device from the device; the second signal having a second frequency; determining a phase pattern of the measured phase of the first signal and a measured phase of the second signal versus frequency, including identifying a relationship between the measured phase and frequency by applying extrapolation to estimate phase values for missing frequencies of a series of measure phase versus frequency values before determining a phase difference between consecutive values of a series of measured phase versus frequency values to estimate a fitting curve of the series of measured phase versus frequency values; pattern matching the phase pattern with a reference phase pattern of a plurality of predetermined reference phase patterns, wherein the reference phase pattern is associated with a distance between the device and the communication device; and determining the distance between the communication device and the device based on the pattern matching. ### Claim 2 (depends on 1) The method according to claim 1, wherein pattern matching the phase pattern with the reference phase pattern of the plurality of predetermined reference phase patterns comprises pattern matching with a derivative of the measured phase with respect to frequency representing a pattern matching feature. ### Claim 3 (depends on 2) The method according to claim 2, wherein pattern matching comprises cosine similarity, Euclidian distance or iterative closest point. ### Claim 4 (depends on 1) The method according to claim 1, wherein determining a phase pattern of a measured phase versus frequency further comprises: determining the phase pattern based on the relationship between the measured phase and the frequency. ### Claim 5 (depends on 1) The method according to claim 1, wherein identifying a relationship between the measured phase and frequency further comprises: computing an error between the fitting curve and the series of measured phase versus frequency values; and determining that no relationship exists between the measured phase and frequency if the error exceeds a threshold. ### Claim 6 (depends on 5) The method according to claim 5 further comprising: determining a stationary device if the error is at or below the threshold. ### Claim 7 (depends on 5) The method according to claim 5 further comprising: determining a non-stationary device when the error exceeds the threshold. ### Claim 8 (depends on 1) The method according to claim 1, wherein phase-unwrapping comprises: adding multiples of +/−Pi when a phase difference between consecutive values of the series of measured phase versus frequency points exceeds a threshold. ### Claim 9 (depends on 8) The method according to claim 8, wherein the threshold is 1.3 times Pi. ### Claim 10 (depends on 8) The method according to claim 8, wherein the threshold is Pi. ### Claim 11 (depends on 1) The method according to claim 1, wherein applying extrapolation comprises applying linear extrapolation. ### Claim 12 (depends on 1) The method according to claim 1, wherein applying extrapolation comprises applying extrapolation when a number of missing frequencies that have been detected in the series of measured phase versus frequency values exceed a threshold. ### Claim 13 (depends on 1) The method according to claim 1, wherein applying extrapolation comprises applying extrapolation when a burst lost block occurs in the series of phase versus frequency values. ### Claim 14 (depends on 1) The method according to claim 1 wherein a range of frequencies bounded by the first frequency and the second frequency comprises a number of skipped frequencies of a pre-arranged hopping sequence at which the communication device operates. ### Claim 15 (depends on 14) The method according to claim 14, wherein a range of frequencies bounded by the first frequency and the second frequency comprises a number of skipped frequencies of a pre-arranged frequency hopping sequence at which the phase is not measured. ### Claim 16 (depends on 14) The method according to claim 14, wherein the pre-arranged frequency hopping sequence is a frequency hopping spread spectrum sequence. ### Claim 17 (depends on 1) The method according to claim 1, wherein frequencies at which the phase is measured are comprised in an Ultra High Frequency (UHF) band. ### Claim 18 (depends on 17) The method according to claim 17, wherein the UHF band is reserved for radio frequency identification (RFID). ### Claim 19 (depends on 18) The method according to claim 18, wherein at least some of subsequent frequencies at which the phase is measured are multiples of 0.5 MHz apart. ### Claim 20 (depends on 1) The method according to claim 1, wherein determining the distance between the communication device and the device based on the pattern matching of the phase pattern against a reference phase pattern comprises determining the distance that corresponds to the reference phase pattern that matches the phase pattern best. ### Claim 21 (depends on 1) The method according to claim 1, wherein the device is an RFID tag and the communication device is an RFID reader. ### Claim 22 An RFID reader comprising a radio frequency (RF) module and a baseband (BB) module, wherein the RF module is configured to: measure a phase of a signal received from an RFID tag, the signal having a first frequency; measure a phase of at least one other signal received from the RFID tag; the at least one other signal having a second frequency; and wherein the BB module is configured to: determine a phase pattern of a measured phase versus frequency based on the measured phase of the signal and the measured phase of the at least one other signal including identifying a relationship between the measured phase and frequency by applying extrapolation to estimate phase values for missing frequencies of a series of measure phase versus frequency values before determining a phase difference between consecutive values of a series of measured phase versus frequency values to estimate a fitting curve of the series of measured phase versus frequency values; pattern matching the phase pattern with a reference phase pattern of a plurality of pre-determined reference phase patterns, wherein the reference phase pattern is associated with a distance between RFID tag and RFID reader; and determine the distance between RFID tag and RFID reader based on the pattern matching. ### Claim 23 A method for localizing a device, the method performed in a communication device, the method comprising: measuring a phase of a first signal received by the communication device from the device, the first signal having a first frequency; measuring a phase of a second signal received by the communication device from the device; the second signal having a second frequency; determining a phase pattern of the measured phase of the first signal and the measured phase of the second signal versus frequency; measuring a phase of a first reference signal received by the communication device from at least one reference device of a known location or distance from the communication device, the first reference signal having a first frequency; measuring a phase of a second reference signal received by the communication device from the at least one reference device; the second reference signal having a second frequency; determining a reference phase pattern of the measured phase of the first reference signal and the measured phase of the second reference signal versus frequency including identifying a relationship between the measured phase and frequency by applying extrapolation to estimate phase values for missing frequencies of a series of measure phase versus frequency values before determining a phase difference between consecutive values of a series of measured phase versus frequency values to estimate a fitting curve of the series of measured phase versus frequency values; and pattern matching the phase pattern with the reference phase pattern, and determining the distance between the communication device and the device or the location of the device based on the pattern matching. ### Claim 24 (depends on 23) The method according to claim 23, wherein determining a phase pattern of a measured phase versus frequency comprises: determining the phase pattern based on the relationship between the measured phase and the frequency. ### Claim 25 (depends on 24) The method according to claim 24, wherein identifying a relationship between the measured phase and frequency comprises: computing an error between the fitting curve and the series of measured phase versus frequency values; and determining that no relationship exists between the measured phase and frequency if the error exceeds a threshold.