# US 2014/0194142 A1 · Wireless localisation system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0194142 A1 - Document ID: US20140194142A1 - Status: Published application - Kind: A1 - Application number: 14/233,997 - Filed: 2011-07-20 - Published: 2014-07-10 - Earliest claimed: 2011-07-20 - Assignees: Commonwealth Scientfic and Industrial Research Organisation - Inventors: Mark Hedley; Yingjie Jay Guo; Xiaojing Huang - Web page: https://patentgrep.com/patent/US20140194142A1 ## CPC - 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 - G01S 13/878: {Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector (G01S13/874 takes precedence)} - G01S 13/76: wherein pulse-type signals are transmitted - 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 Disclosed is an apparatus for estimating the location of a remote node. The apparatus comprises an antenna array comprising a plurality of elements in a fixed spatial arrangement, at least one element being a transmitting element configured to transmit a first wireless signal to the remote node, and at least two elements being receiving elements configured to receive a second wireless signal transmitted by the remote node in response to the first wireless signal. The apparatus further comprises a signal processing unit connected to the antenna array, the signal processing unit being configured to: estimate a plurality of round trip distances using the wireless signals, each round trip distance being from a transmitting element to the remote node and back to a receiving element; and estimate the location of the remote node using the round trip distance estimates. ## Claims ### Claim 1 An apparatus for estimating the location of a remote node, the apparatus comprising: an antenna array comprising a plurality of elements in a fixed spatial arrangement, at least one element being a transmitting element configured to transmit a first wireless signal to the remote node, and at least two elements being receiving elements configured to receive a second wireless signal transmitted by the remote node in response to the first wireless signal; and a signal processing unit connected to the antenna array, the signal processing unit being configured to: to estimate a plurality of round trip distances using the wireless signals, each round trip distance being from a transmitting element to the remote node and back to a receiving element; and estimate the location of the remote node using the round trip distance estimates. ### Claim 2 (depends on 1) An apparatus according to claim 1, wherein the location estimating comprises solving a linear equation relating the location of the remote node to the round trip distance estimates via an array matrix. ### Claim 3 (depends on 2) An apparatus according to claim 2, wherein the solution is a least squares solution. ### Claim 4 (depends on 1) An apparatus according to claim 1, wherein: each receiving element is configured to measure the time-of-arrival of the second wireless signal relative to a common clock, the remote node is configured to measure the time-of-arrival of the first wireless signal from the transmitting element, and the signal processing unit is configured to estimate the round trip distances using the measured times-of-arrival. ### Claim 5 (depends on 1) An apparatus according to claim 1, wherein each receiving element is configured to measure the phase of the second wireless signal relative to a common reference phase, and the signal processing unit is configured to estimate the location of the remote node using the phase measurements as well as the round trip distance estimates. ### Claim 6 (depends on 1) An apparatus according to claim 1, wherein each receiving element is a transmitting element, and each round trip distance is from an element to the remote node and back to that element. ### Claim 7 (depends on 1) An apparatus according to claim 1, wherein each round trip distance is from a transmitting element to the remote node and back to a receiving element. ### Claim 8 (depends on 5) An apparatus according to claim 5, wherein the location estimating comprises jointly solving a linear equation relating the location of the remote node to the round trip distance estimates via an array matrix, and a linear equation relating the location of the remote node to the phase measurements via a phase array matrix. ### Claim 9 (depends on 8) An apparatus according to claim 8, wherein the solution is a weighted least squares solution, weighted by the variance of the errors in the round trip distance estimates, and the variance of the errors in the phase measurements. ### Claim 10 (depends on 5) An apparatus according to claim 5, wherein the signal processing unit is further configured to resolve the ambiguity in the phase measurements. ### Claim 11 (depends on 10) An apparatus according to claim 10, wherein the ambiguity resolving comprises: estimating a bearing of the remote node using the round trip distance estimates; computing, for each receiving element, an integer that embodies the phase ambiguity using the bearing estimate, wherein the estimating the location of the remote node uses the computed integers to resolve the ambiguity in the respective phase measurements. ### Claim 12 (depends on 10) An apparatus according to claim 10, wherein the ambiguity resolving comprises: estimating a bearing of the remote node using the round trip distance estimates; finding a plurality of peaks in the array pattern around the bearing estimate; computing, for each peak, and for each receiving element, an integer that embodies the phase ambiguity using the bearing estimate; forming, for each peak, an estimate of the location of the remote node using the computed integers to resolve the ambiguity in the respective phase measurements, and a corresponding error; choosing the location estimate yielding the smallest error. ### Claim 13 (depends on 1) An apparatus according to claim 1, wherein the location estimating comprises minimising a cost function of the range and bearing of the remote node, the parameters of the cost function being the round trip distance estimates and the location of each receiving element. ### Claim 14 (depends on 5) An apparatus according to claim 5, wherein the location estimating comprises minimising a cost function of the range and bearing of the remote node, the parameters of the cost function being the round trip distance estimates, the phase measurements, and the location of each receiving element. ### Claim 15 A method of estimating a location of a remote node, the method comprising: estimating a plurality of round trip distances, each round trip distance being from a transmitting element to the remote node and back to one of a plurality of receiving elements based on a first wireless signal transmitted by the transmitting element to the mobile node and a second wireless signal transmitted by the mobile node to the receiving element; and estimating the location of the remote node using the round trip distance estimates.