# US 11,910,276 B2 · Rapid detection of mobile station locations using Wi-Fi > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,910,276 B2 - Document ID: US11910276B2 - Status: Granted - Kind: B2 - Application number: 17/493,893 - Filed: 2021-10-05 - Published: 2023-04-06 - Granted: 2024-02-20 - Earliest claimed: 2021-10-05 - Assignees: Deeyook Location Technologies Ltd. - Applicants: Deeyook Location Technologies Ltd. - Inventors: Eran Shpak - Web page: https://patentgrep.com/patent/US11910276B2 ## CPC - H04W 4/02: Services making use of location information - H04W 4/029: Location-based management or tracking services - H04L 1/1607: Details of the supervisory signal - H04W 4/80: Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication - H04W 16/28: using beam steering - H04W 64/006: {with additional information processing, e.g. for direction or speed determination} - 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) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method for communication includes identifying a media access control (MAC) address of a mobile station of interest. Independently of receiving any probe request frame from the mobile station, a probe response frame addressed to the identified MAC address is transmitted over a wireless local area network (WLAN). An acknowledgment of the probe response frame is received from the mobile station and is used in ascertaining a location of the mobile station. ## Claims ### Claim 1 A method for communication, comprising: identifying a media access control (MAC) address of a mobile station of interest; independently of receiving any probe request frame from the mobile station, transmitting a probe response frame addressed to the identified MAC address over a wireless local area network (WLAN); receiving an acknowledgment of the probe response frame from the mobile station; and ascertaining a location of the mobile station responsively to the received acknowledgment. ### Claim 2 (depends on 1) The method according to claim 1, wherein transmitting the probe response frame comprises transmitting probe response frames over multiple frequency channels of the WLAN. ### Claim 3 (depends on 2) The method according to claim 2, wherein transmitting the probe response frames comprises scanning sequentially over the channels of the WLAN, and transmitting a respective probe response frame over each of the channels until the acknowledgment is received. ### Claim 4 (depends on 1) The method according to claim 1, wherein the acknowledgment is received within 10 μs of transmitting the probe response frame. ### Claim 5 (depends on 4) The method according to claim 4, wherein ascertaining the location comprises identifying the mobile station as a sender of the acknowledgment responsively to receiving the acknowledgment within 10 μs of transmitting the probe response frame. ### Claim 6 (depends on 1) The method according to claim 1, wherein ascertaining the location comprises identifying that the mobile station is located within a communication range of a receiver that receives the acknowledgment. ### Claim 7 (depends on 1) The method according to claim 1, wherein ascertaining the location comprises estimating an angular direction of arrival from the mobile station based on a radio signal conveying the acknowledgment. ### Claim 8 (depends on 7) The method according to claim 7, wherein transmitting the probe response frame comprises transmitting probe response frames addressed to the identified MAC address from multiple different positions, and wherein estimating the angular direction of arrival from the mobile station comprises finding respective angular arrival directions from the mobile station to the multiple different positions based on acknowledgments received at the multiple different positions, and finding location coordinates of the mobile station by triangulation of the respective angular directions of arrival. ### Claim 9 (depends on 7) The method according to claim 7, wherein the acknowledgment is received by receivers at multiple different positions, and wherein estimating the angular direction of arrival from the mobile station comprises finding respective angular directions from the mobile station to the multiple different positions based on the acknowledgments received at the multiple different positions, and finding location coordinates of the mobile station by triangulation of the respective angular directions of arrival. ### Claim 10 (depends on 1) The method according to claim 1, wherein transmitting the probe response comprises transmitting a first orthogonal frequency-domain multiplexing (OFDM) signal, and wherein receiving the acknowledgment comprises receiving a second OFDM signal in response to the first OFDM signal, and wherein ascertaining the location comprises processing the second OFDM signal in order to find an angle of arrival of the acknowledgment. ### Claim 11 Apparatus for communication, comprising: a wireless transceiver, which is configured to identify a media access control (MAC) address of a mobile station of interest and, independently of receiving any probe request frame from the mobile station, to transmit a probe response frame addressed to the identified MAC address over a wireless local area network (WLAN), and to receive an acknowledgment from the mobile station of the probe response frame; and a processor, which is configured to ascertain a location of the mobile station responsively to the received acknowledgment. ### Claim 12 (depends on 11) The apparatus according to claim 11, wherein the wireless transceiver is configured to transmit probe response frames and to receive acknowledgments over multiple frequency channels of the WLAN. ### Claim 13 (depends on 12) The apparatus according to claim 12, wherein the wireless transceiver is configured to scan sequentially over the channels of the WLAN, and to transmit a respective probe response frame over each of the channels until the acknowledgment is received. ### Claim 14 (depends on 11) The apparatus according to claim 11, wherein the acknowledgment is received within 10 μs of transmitting the probe response frame. ### Claim 15 (depends on 14) The apparatus according to claim 14, wherein the processor is configured to identify the mobile station as a sender of the acknowledgment responsively to receiving the acknowledgment within 10 μs of transmitting the probe response frame. ### Claim 16 (depends on 11) The apparatus according to claim 11, wherein the processor is configured to identify, responsively to the received acknowledgment, that the mobile station is located within a communication range of the wireless transceiver that received the acknowledgment. ### Claim 17 (depends on 11) The apparatus according to claim 11, wherein the processor is configured to estimate an angular direction of arrival from the mobile station based on a radio signal conveying the received acknowledgment. ### Claim 18 (depends on 17) The apparatus according to claim 17, wherein the probe response frames addressed to the identified MAC address are transmitted from multiple different positions, and wherein the processor is configured to find respective angular directions of arrival from the mobile station to the multiple different positions based on acknowledgments received at the multiple different positions, and to find location coordinates of the mobile station by triangulation of the respective angular directions of arrival. ### Claim 19 (depends on 11) The apparatus according to claim 11, wherein the acknowledgment is received by receivers at multiple positions, and wherein the processor is configured to find respective angular directions of arrival from the mobile station to the multiple different positions based on the acknowledgments received at the multiple different positions, and to find location coordinates of the mobile station by triangulation of the respective angular directions. ### Claim 20 (depends on 11) The apparatus according to claim 11, wherein the wireless transceiver is configured to transmit the probe response as a first orthogonal frequency-domain multiplexing (OFDM) signal, which causes the mobile station to transmit the acknowledgment as a second OFDM signal in response to the first OFDM signal, and wherein the processor is configured to process the second OFDM signal in order to find an angle of arrival of the acknowledgment. ### Claim 21 A communication system, comprising: a plurality of wireless tags, which are configured to be fixed to respective items, each tag having a respective media access control (MAC) address that is defined for communication over a wireless local area network (WLAN); a wireless transceiver, which is configured to identify the respective MAC address of a tag that is fixed to an item of interest and, independently of receiving any probe request frame from the transceiver, to transmit a probe response frame addressed to the identified MAC address over the WLAN, and to receive an acknowledgment of the probe response frame from the tag; and a processor, which is configured to ascertain a location of the item of interest responsively to the received acknowledgment. ### Claim 22 (depends on 21) The system according to claim 21, wherein the acknowledgment is received within 10 μs of transmitting the probe response frame. ### Claim 23 (depends on 22) The apparatus according to claim 22, wherein the processor is configured to identify the tag as a sender of the acknowledgment responsively to receiving the acknowledgment within 10 μs of transmitting the probe response frame. ### Claim 24 (depends on 21) The apparatus according to claim 21, wherein the processor is configured to identify, responsively to the received acknowledgment, that the tag is located within a communication range of the wireless transceiver that received the acknowledgment. ### Claim 25 (depends on 21) The apparatus according to claim 21, wherein the processor is configured to estimate an angular direction of arrival from the mobile station based on a radio signal conveying the received acknowledgment.