# US 10,873,947 B2 · Internet of things (IoT) device location tracking using midambles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,947 B2 - Document ID: US10873947B2 - Status: Granted - Kind: B2 - Application number: 16/287,388 - Filed: 2019-02-27 - Published: 2020-08-27 - Granted: 2020-12-22 - Earliest claimed: 2019-02-27 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Matthew Silverman; Paul J. Stager; Xu Zhang - Web page: https://patentgrep.com/patent/US10873947B2 ## CPC - H04W 72/51: based on terminal or device properties - H04B 7/0404: the mobile station comprising multiple antennas, e.g. to provide uplink diversity - H04L 5/0023: {Time-frequency-space} - H04L 5/0044: {Allocation of payload; Allocation of data channels, e.g. PDSCH or PUSCH} - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04B 7/0802: {using antenna selection (H04B7/0868 takes precedence; antenna beam directivity switching H01Q3/24)} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 5/0057: {Physical resource allocation for CQI} - H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In one embodiment, a technique for Internet of Things (IoT) device location tracking using midambles is provided. A first wireless device in connection with an antenna array may receive one or more first data symbols of a data payload from a second wireless device using a first antenna state that assigns a radio path, used for location estimation, to a first antenna of the antenna array. Subsequent to identifying a first midamble of the data payload, the first wireless device may change the first antenna state to a second antenna state that assigns the radio path to a second antenna of the antenna array. The first wireless device may receive one or more second data symbols of the data payload using the second antenna state. The first wireless device may determine a location of the second wireless device based on location information determined using the radio path. ## Claims ### Claim 1 A method, comprising: receiving, by a first wireless device in connection with an antenna array, one or more first data symbols of a data payload from a second wireless device using a first antenna state, the first antenna state assigning a radio path that is used for location estimation to a first antenna of the antenna array; changing, by the first wireless device, the first antenna state to a second antenna state subsequent to identifying a first midamble of the data payload, the second antenna state assigning the radio path to a second antenna of the antenna array; receiving, by the first wireless device, one or more second data symbols of the data payload from the second wireless device using the second antenna state; and determining, by the first wireless device, a location of the second wireless device based on location information determined using the radio path. ### Claim 2 (depends on 1) The method of claim 1, further comprising: sending, by the first wireless device, a trigger frame to the second wireless device, the trigger frame configuring a frequency of insertion of midambles into the data payload. ### Claim 3 (depends on 2) The method of claim 2, wherein the frequency of insertion is based on a number of spatial streams supported by the first wireless device. ### Claim 4 (depends on 1) The method of claim 1, wherein the first antenna state and the second antenna state assign a different radio path to an antenna different than the first antenna and the second antenna, the different radio path used for sounding with the second wireless device. ### Claim 5 (depends on 1) The method of claim 1, wherein changing, by the first wireless device, the first antenna state to the second antenna state comprises: using, by the first wireless device, a radio frequency (RF) switch connected to the antenna array to switch the radio path from the first antenna to the second antenna, the RF switch including general purpose input/output (GPIO). ### Claim 6 (depends on 1) The method of claim 1, wherein determining, by the first wireless device, the location of the second wireless device based on location information determined using the radio path comprises: implementing a location estimation technique, the location estimation technique selected from the group consisting of: angle of arrival (AoA) location estimation, time of flight (ToF) location estimation, and received signal strength indicator (RSSI) location estimation. ### Claim 7 (depends on 1) The method of claim 1, further comprising: changing, by the first wireless device, the second antenna state to a third antenna state subsequent to identifying a second midamble of the data payload, the third antenna state assigning the radio path to a third antenna of the antenna array; and receiving, by the first wireless device, one or more third data symbols of the data payload from the second wireless device using the third antenna state. ### Claim 8 (depends on 1) The method of claim 1, wherein the data payload comprises a high efficiency (HE) physical layer (PHY) protocol data unit (PPDU). ### Claim 9 (depends on 1) The method of claim 1, wherein the first wireless device comprises an access point (AP) and the second wireless device comprises an Internet of Things (IoT) device associated with the AP. ### Claim 10 (depends on 1) The method of claim 1, wherein the first wireless device comprises an Internet of Things (IoT) device associated with an access point (AP) and the second wireless device comprises the AP. ### Claim 11 An apparatus, comprising: one or more network interfaces to communicate with a network, the one or more network interfaces including an antenna array; a processor coupled to the network interfaces and configured to execute one or more processes; and a memory configured to store a process executable by the processor, the process, when executed, is configured to: receive one or more first data symbols of a data payload from a wireless device using a first antenna state, the first antenna state assigning a radio path that is used for location estimation to a first antenna of the antenna array; change the first antenna state to a second antenna state subsequent to identifying a first midamble of the data payload, the second antenna state assigning the radio path to a second antenna of the antenna array; receive one or more second data symbols of the data payload from the wireless device using the second antenna state; and determine a location of the wireless device based on location information determined using the radio path. ### Claim 12 (depends on 11) The apparatus as in claim 11, wherein the process, when executed, is further configured to: send a trigger frame to the wireless device, the trigger frame configuring a frequency of insertion of midambles into the data payload. ### Claim 13 (depends on 12) The apparatus as in claim 12, wherein the frequency of insertion is based on a number of spatial streams supported by the first wireless device. ### Claim 14 (depends on 11) The apparatus as in claim 11, wherein the first antenna state and the second antenna state assign a different radio path to an antenna different than the first antenna and the second antenna, the different radio path used for sounding with the wireless device. ### Claim 15 (depends on 11) The apparatus as in claim 11, wherein the process, when executed to change the first antenna state to the second antenna state, is further configured to: use a radio frequency (RF) switch connected to the antenna array to switch the radio path from the first antenna to the second antenna, the RF switch including general purpose input/output (GPIO). ### Claim 16 (depends on 11) The apparatus as in claim 11, wherein the process, when executed to determine the location of the wireless device based on location information determined using the radio path, is further configured to: implement a location estimation technique, the location estimation technique selected from the group consisting of: angle of arrival (AoA) location estimation, time of flight (ToF) location estimation, and received signal strength indicator (RSSI) location estimation. ### Claim 17 (depends on 11) The apparatus as in claim 11, wherein the data payload comprises a high efficiency (HE) physical layer (PHY) protocol data unit (PPDU). ### Claim 18 (depends on 11) The apparatus as in claim 11, wherein the apparatus comprises an access point (AP) and the wireless device comprises an Internet of Things (IoT) device associated with the AP. ### Claim 19 (depends on 11) The apparatus as in claim 11, wherein the apparatus comprises an Internet of Things (IoT) device associated with an access point (AP) and the wireless device comprises the AP. ### Claim 20 A tangible, non-transitory, computer-readable medium storing program instructions executable by a processor, wherein the program instructions cause a first wireless device in connection with an antenna array to execute a process comprising: receiving one or more first data symbols of a data payload front a second wireless device using a first antenna state, the first antenna state assigning a radio path that is used for location estimation to a first antenna of the antenna array; changing the first antenna state to a second antenna state subsequent to identifying a first midamble of the data payload, the second antenna state assigning the radio path to a second antenna of the antenna array; receiving one or more second data symbols of the data payload from the second wireless device using the second antenna state; and determining a location of the second wireless device based on location information determined using the radio path.