# US 12,010,586 B2 · Position estimation method, position estimation system, position estimation server, and position estimation program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,010,586 B2 - Document ID: US12010586B2 - Status: Granted - Kind: B2 - Application number: 17/428,270 - Filed: 2020-01-27 - Published: 2022-04-07 - Granted: 2024-06-11 - Earliest claimed: 2019-02-06 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Masamichi Hosoda; Tadashi Mori; Masaru Miyamoto; Hiroshi Sakamoto; Tomoki Murakami; Tomoaki Ogawa - Web page: https://patentgrep.com/patent/US12010586B2 ## CPC - H04B 17/27: for locating or positioning the transmitter - H04W 4/029: Location-based management or tracking services - G01S 5/02: using radio waves (using satellite radio beacon systems for determining position G01S19/00) - G01S 5/14: Determining absolute distances from a plurality of spaced points of known location - G01S 7/006: {using shared front-end circuitry, e.g. antennas (G01S13/765, G01S13/825 take precedence)} - G01S 13/765: {with exchange of information between interrogator and responder} - G01S 13/876: {Combination of several spaced transponders or reflectors of known location for determining the position of a receiver (G01S13/874 takes precedence)} - H04L 43/0864: Round trip delays - H04B: TRANSMISSION - 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 - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Provided is a position estimation method in which a measurement signal and a response signal are transmitted and received between multiple n wireless stations respectively provided with known antennas installed at known positions different from each other and a wireless terminal station provided with a terminal antenna, RTT, which is a round-trip delay time of the transmission and reception, and RSSI, which is a strength of received radio waves of the signals, are measured, and a position of the wireless terminal station is estimated. The method includes: obtaining, as the position of the wireless terminal station, a solution of simultaneous equations of an RTT evaluation function fti for evaluating the estimate value of the position of the wireless terminal station that is estimated based on the RTT measured between the wireless terminal station and the known antenna i (i=1, 2, . . . , n), and an RSSI evaluation function fri for evaluating the estimate value of the position of the wireless terminal station that is estimated based on the RSSI, or a value obtained by searching for an estimate value so that an error evaluation function ferror obtained by combining the RTT evaluation function and the RSSI evaluation function is minimum. ## Claims ### Claim 1 A position estimation method comprising: transmitting a measurement signal and receiving a response signal between multiple n wireless stations respectively provided with known antennas i (i=1, 2, . . . , n) installed at known positions different from each other and a wireless terminal station provided with a terminal antenna installed at an unknown position; measuring RTT, which is a round-trip delay time of the transmission and the reception; obtaining coordinate information of an estimated position of the wireless terminal station with the terminal antenna in response to the measured RTT by the known antennas i; applying the coordinate information to an RTT evaluation function fti to evaluate the estimated position of the wireless terminal station with the terminal antenna, the RTT evaluation function fti having terms relating to the coordinate information, a value of each of the terms being variable; determine, by using a range evaluation function k, whether the value of each of the terms of the RTT evaluation function fti is within an acceptable range in which the wireless terminal station with the terminal antenna is to be present, the range evaluation function fL having the terms; setting a value of each of the terms of the range evaluation function fL to zero when the value of each of the terms of the RTT evaluation function fti is within the acceptable range; setting the value of each of the terms of the range evaluation function fL to a proportional value when the value of each of the terms of the RTT evaluation function fti deviates from the acceptable range by a deviation amount, the proportional value being larger as the deviation amount becomes larger; and estimating a position of the wireless terminal station with the terminal antenna based on either: a solution of simultaneous equations of the RTT evaluation function fti and the range evaluation function fL; or a value obtained by searching for an estimate value in a case in which an error evaluation function ferror obtained by combining the RTT evaluation function fti and the range evaluation function fL is minimum. ### Claim 2 (depends on 1) A position estimation system for estimating the position of the wireless terminal station by the position estimation method according to claim 1, wherein the RTT measured by each of the multiple n wireless stations is forwarded to a position estimation server, and the position estimation server is configured to calculate the RTT evaluation function fti and obtain the position of the wireless terminal station. ### Claim 3 (depends on 1) A position estimation system for estimating the position of the wireless terminal station by the position estimation method according to claim 1, wherein the multiple n known antennas are distributed antennas that are disposed while being distributed from a wireless base station via cables having known lengths, the RTT measured for each distributed antenna by the wireless base station is forwarded to a position estimation server, and the position estimation server is configured to calculate the RTT evaluation function fti and obtain the position of the wireless terminal station. ### Claim 4 (depends on 1) A position estimation server for estimating the position of the wireless terminal station by the position estimation method according to claim 1, wherein the RTT measured by each of the multiple n wireless stations is forwarded to the position estimation server, and the position estimation server is configured to calculate the RTT evaluation function fti and obtain the position of the wireless terminal station. ### Claim 5 (depends on 4) A non-transitory computer-readable medium having computer-executable instructions that, upon execution of the computer-executable instructions by a processor of a computer, cause the position estimation server according to claim 4 to function, so as to calculate the RTT evaluation function fti and obtain the position of the wireless terminal station. ### Claim 6 (depends on 1) The position estimation method according to claim 1, further comprising: calculating reliability w of the measured RTT by the known antennas i based on a number of the measurements and standard deviation; and giving a weight wti corresponding to the reliability w to the RTT evaluation function fti. ### Claim 7 A position estimation method comprising: transmitting a measurement signal and receiving a response signal between multiple n wireless stations respectively provided with known antennas i (i=1, 2, . . . , n) installed at known positions different from each other and a wireless terminal station provided with a terminal antenna installed at an unknown position; measuring RTT, which is a round-trip delay time of the transmission and the reception; measuring RSSI, which is a strength of received radio waves of the signals; obtaining coordinate information of an estimated position of the wireless terminal station with the terminal antenna in response to the measured RTT and the measured RSSI by the known antennas i; applying the coordinate information to an RTT evaluation function fti and an RSSI evaluation function fri to evaluate the estimated position of the wireless terminal station with the terminal antenna, each of the RTT evaluation function fti and the RSSI evaluation function fri having terms relating to the coordinate information, a value of each of the terms being variable; determine, by using a range evaluation function k, whether the value of each of the terms of the RTT evaluation function fti and the RSSI evaluation function fri is within an acceptable range in which the wireless terminal station with the terminal antenna is to be present, the range evaluation function fL having the terms; setting a value of each of the terms of the range evaluation function fL to zero when the value of each of the terms of the RTT evaluation function fti and the RSSI evaluation function fri is within the acceptable range; setting the value of each of the terms of the range evaluation function fL to a proportional value when the value of each of the terms of the RTT evaluation function fti and the RSSI evaluation function fri deviates from the acceptable range by a deviation amount, the proportional value being larger as the deviation amount becomes larger; and estimating a position of the wireless terminal station with the terminal antenna based on either: a solution of simultaneous equations of the RTT evaluation function fti, the RSSI evaluation function fri, and the range evaluation function fL; or a value obtained by searching for an estimate value in a case in which an error evaluation function ferror obtained by combining the RTT evaluation function fti, the RSSI evaluation function fri, and the range evaluation function fL is minimum. ### Claim 8 (depends on 7) A position estimation system for estimating the position of the wireless terminal station by the position estimation method according to claim 7, wherein the RTT and the RSSI measured by each of the multiple n wireless stations are forwarded to a position estimation server, and the position estimation server is configured to calculate the RTT evaluation function fti and the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 9 (depends on 7) A position estimation system for estimating the position of the wireless terminal station by the position estimation method according to claim 7, wherein the multiple n known antennas are distributed antennas that are disposed while being distributed from a wireless base station via cables having known lengths, the RTT and the RSSI measured for each distributed antenna by the wireless base station are forwarded to a position estimation server, and the position estimation server is configured to calculate the RTT evaluation function fti and the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 10 (depends on 7) A position estimation server for estimating the position of the wireless terminal station by the position estimation method according to claim 7, wherein the RTT and the RSSI measured by each of the multiple n wireless stations are forwarded to the position estimation server, and the position estimation server is configured to calculate the RTT evaluation function fti and the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 11 (depends on 10) A non-transitory computer-readable medium having computer-executable instructions that, upon execution of the computer-executable instructions by a processor of a computer, cause the position estimation server according to claim 10 to function, so as to calculate the RTT evaluation function fti and the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 12 (depends on 7) The position estimation method according to claim 7, further comprising: calculating first reliability w1 of the measured RTT by the known antennas i based on a number of the measurements and standard deviation; calculating second reliability w2 of the measured RSSI by the known antennas i based on a number of the measurements and standard deviation; giving a weight wti corresponding to the first reliability w1 to the RTT evaluation function fti; and giving a weight wri corresponding to the second reliability w2 to the RSSI evaluation function fri. ### Claim 13 A position estimation method comprising: transmitting a measurement signal and receiving a response signal between multiple n wireless stations respectively provided with known antennas i (i=1, 2, . . . , n) installed at known positions different from each other and a wireless terminal station provided with a terminal antenna installed at an unknown position; measuring RSSI, which is a strength of received radio waves of the signals; obtaining coordinate information of an estimated position of the wireless terminal station with the terminal antenna in response to the measured RSSI by the known antennas i; applying the coordinate information to an RSSI evaluation function fri to evaluate the estimated position of the wireless terminal station with the terminal antenna, the RSSI evaluation function fri having terms relating to the coordinate information, a value of each of the terms being variable; determine, by using a range evaluation function fL, whether the value of each of the terms of the RSSI evaluation function fri is within an acceptable range in which the wireless terminal station with the terminal antenna is to be present, the range evaluation function fL having the terms; setting a value of each of the terms of the range evaluation function fL to zero when the value of each of the terms of the RSSI evaluation function fri is within the acceptable range; setting the value of each of the terms of the range evaluation function fL to a proportional value when the value of each of the terms of the RSSI evaluation function fri deviates from the acceptable range by a deviation amount, the proportional value being larger as the deviation amount becomes larger; and estimating a position of the wireless terminal station with the terminal antenna based on either: a solution of simultaneous equations of the RSSI evaluation function fri and the range evaluation function fL; or a value obtained by searching for an estimate value in a case in which an error evaluation function ferror obtained by combining the RSSI evaluation function fri and the range evaluation function fL is minimum. ### Claim 14 (depends on 13) A position estimation system for estimating the position of the wireless terminal station by the position estimation method according to claim 13, wherein the RSSI measured by each of the multiple n wireless stations is forwarded to a position estimation server, and the position estimation server is configured to calculate the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 15 (depends on 13) A position estimation system for estimating the position of the wireless terminal station by the position estimation method according to claim 13, wherein the multiple n known antennas are distributed antennas that are disposed while being distributed from a wireless base station via cables having known lengths, the RSSI measured for each distributed antenna by the wireless base station is forwarded to a position estimation server, and the position estimation server is configured to calculate the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 16 (depends on 13) A position estimation server for estimating the position of the wireless terminal station by the position estimation method according to claim 13, wherein the RSSI measured by each of the multiple n wireless stations is forwarded to the position estimation server, and the position estimation server is configured to calculate the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 17 (depends on 16) A non-transitory computer-readable medium having computer-executable instructions that, upon execution of the computer-executable instructions by a processor of a computer, cause the position estimation server according to claim 16 to function, so as to calculate the RSSI evaluation function fri and obtain the position of the wireless terminal station. ### Claim 18 (depends on 13) The position estimation method according to claim 13, further comprising: calculating reliability w of the measured RSSI by the known antennas i based on a number of the measurements and standard deviation; and giving a weight wri corresponding to the reliability w to the RSSI evaluation function fri.