Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0205—Details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
  • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
  • G01S3/023—Monitoring or calibrating
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
  • G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
  • G01S13/765—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted with exchange of information between interrogator and responder
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0246—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves involving frequency difference of arrival or Doppler measurements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/12—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
  • H04B7/0695—Hybrid systems, i.e. switching and simultaneous transmission using beam selection
  • H04B7/06952—Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping
  • H04B7/06958—Multistage beam selection, e.g. beam refinement
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0091—Signalling for the administration of the divided path, e.g. signalling of configuration information
  • H04L5/0092—Indication of how the channel is divided
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/02—Services making use of location information
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/02—Services making use of location information
  • H04W4/029—Location-based management or tracking services
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
  • H04W64/006—Locating users or terminals or network equipment for network management purposes, e.g. mobility management with additional information processing, e.g. for direction or speed determination
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
  • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
  • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
  • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
  • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
  • H04B7/0636—Feedback format
  • H04B7/0643—Feedback on request
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0001—Arrangements for dividing the transmission path
  • H04L5/0014—Three-dimensional division
  • H04L5/0023—Time-frequency-space
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
  • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
  • H04W16/24—Cell structures
  • H04W16/28—Cell structures using beam steering
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
  • H04W76/14—Direct-mode setup

Definitions

• the subject: matter disclosed herein relates to wireless communication and specifically to unicast, multicast, and/or broadcast protocols for sounding, ranging and/or direction finding in wireless communication systems.
• UE such as a mobile terminal, laptop, wearable, tablet, a cellular phone or other mobile device.
• location and “position” arc synonymous and are used interchangeably herein.
• positioning ma be performed u ing Round Trip Time (TT) measurements between an Access Point (AP) and User E uipment (UE).
• TT Round Trip Time
• multiple antennas at the transmitter and receiver may be used to implement multiple input multiple output (MiMO).
• MiMO facilitates parallel delivery of multiple spatially multiplexed data signals, which are referred to as multiple spatial streams.
• beamforming may be used for directional signal transmission or reception. In beamfomiing, elements in a phased arra antenna are combined so that signals at some angles experience constructive
• Beamforitiiiig can be used to achieve spatial selectivity at the transmi&ma and receiving ends. Techniques to facilitate beaniforming calibration may therefore provide i mproved.
• a method on a first station may comprise: broadcasting a first Null Data Packet Announcement (NDPA) frame, the first NDPA frame comprising an indication of one or more second STAs being polled; broadcasting, subsequent t the first NDPA frame, a Mull Data Packet (HDP) frame i ony a plurality of antennas on the first STA; and receiving, from the one or more second STAs, in response to the NDP frame, one or more corresponding first Fine Timing Measurement (FTM) frames.
• Each corresponding first FTM frame may: he received from a distinct corresponding second STA of the one or more second STAs; and, comprise
• a first STA may comprise: a processor coupled to a memor and a piurality of antennas, wherein the processor is configured to: broadcast a first Null Data Packet Announcement (NDPA) frame, the first NDPA frame comprising an indication of one or more second STAs being poiied; broadcast, subsequent to the first NDPA frame, a Null Data Packet (NDP) frame from the plurality of antennas: and receive, from the one or more second STAs, in response to the NDP frame, one or more corresponding first Fine Timing Measurement (FTM) frames.
• NDPA Null Data Packet Announcement
• FTM Fine Timing Measurement
• Each corresponding first FTM frame may: be received from a disti.net corresponding second STA of the one or more second STAs; and, comprise corresponding first ranging .measurements between the first STA and the corresponding second STA as determined by the corresponding second STA based, in part, on the NDP frame.
• a first station may comprise: means for broadcasting a first Null Data Packet Announcement (NDPA) frame, the first NDPA f ame comprising an indication of one or more second STAs being polled; means for broadcasting, subsequent to the first NDPA frame, a ull Data Packet (NDP) frame from a plurality of antennas on the first STA; means for recei ving, from the one or .more second STAs, in response to the NDP frame, one or more corresponding first Fine Timing Measurement (FTM) frames.
• NDPA Null Data Packet Announcement
• NDP ull Data Packet
• FTM Fine Timing Measurement
• Each coirespoading first FTM frame may: be received from a distinct correspond ing second STA of the one or more second STAs; and, comprise corresponding first ranging measurements between the first STA and the corresponding second STA as determined by the corresponding second STA based, in part, on the NDP frame.
• a non-transitory computer-readable medium may comprise execiitabie instructions to confi ure a processor to; broadcast a first Mull Data Packet Announcement (NDPA) -frame, the first NDPA frame comprising an indication of one or more second STAs being polled; broadcast, subsequent to the first N DPA frame, a Null Data Packet (NDP) frame from the plurality of antennas; and receive, from the one or more second STAs, in response to the NDP frame, one or more corresponding first Fine Timing Measurement (FTM) frames.
• NDPA Mull Data Packet Announcement
• NDP Null Data Packet
• FTM Fine Timing Measurement
• Each corresponding first FTM frame may; be received from a distinct corresponding second STA of the one or more second STAs; and, comprise corresponding first ranging measurements between the first STA and the corresponding second STA as determined by the corresponding second STA based, in part, on the NDP frame.
• the methods disclosed may be performed by one or more of APs, non-
• Embodiments disclosed also relate to software, firmware, and program instructions created, stored, accessed, read or modified by processors using non-transitory computer readable media or computer readable memory.
• FIG. 1 shows a schematic block diagram ilMstrating certain exemplary features of a non-AP STA shown as UE 100 enabled to perform wireless
• Fig, 2 shows a simplified architecture of a wireless communication system 200 irt accordance with certain embodiments presented herein.
• FIG. 3 shows schematic block diagram illustrating an AP STA shown as
• AP 240 enabled to perform wireless communication including unkast, multicast, and/or broadcast, and wireless medium characterization in a wireless environment in
• Fig, 4A shows an exemplary DPA frame 400 with information pertaining to a subsequent NDP frame in accordance with certain embodiments presented herein.
• [001 Sf Fig, B shows the format of the Sounding Dialo Token field 430 including a Reserved Sub-field 432 wife a 2-bit length and Soundin Dialog Token • Number suhfield 434 in accordance with certain embodiments presented herein,
• Fig, 5 A shows au example Fine Timing Measurement (FTM) frame- 500, which ma include AoA, AoD, and/or other information in accordance with certain embodiments presented herein.
• FTM Fine Timing Measurement
• FIGS. 5B and 5C show the formats of example AoA field 530 and AoD field 540, respectively, in accordance with certain embodiments presented herein.
• FIG. 5D shows a portion 550 of an example Fine Timing Measurement
• FTM FTM / FTM No Ack frame 500 indicating that a response may he sent as an FTM Acknowledgement (FTM Ack) frame.
• FIG, SE is an example 3-dintensional coordinate system 580 fo represenfiii the position of a STA using a radius ⁇ ' and angles "theta * " and "phi"
• Fig. 6 shows an exemplary message flow 600 for location determination.
• message flo 600 may occur ' between a first STA I 602 (e.g. an AP) and a plurality of other STAs, shown as STA2 604 . . . STA_A- . . . STAz ' 606, where 2 ⁇ k ⁇ z,
• FIG. 7 shows an exemplars' message flow 700 to facilitate location determination between a first STA1 702. (e.g. an AP) and a plurality of oilier STAs, shown as STA2 70 . . . STAJc , . . ST Ax 707 , , , S Az 706, where 2 ⁇ k ⁇ z in a
• STA1 702. e.g. an AP
• LA environment supporting uplink multiuser capabilities such as Uplink MU- MIMO.
• Fig. 8 shows a timeline 800 of events associated with the message flow sequence in Fig, 7.
• FIG. 9 shows an exemplary flowchart 900 of a method for ranging and/or location determination according to disclosed embodiments
• Embodiments disclosed facilitate wireless communication between devices.
• wireless communication is facilitated through the use of protocols or. modifications to protocols that assist in channel calibration.
• chan el calibration may .include performing measurements related to sounding, ranging, and/or direction finding.
• disclosed techniques may be used in wireless environments to facilitate ranging and direction finding between devices.
• disclosed embodiments may facilitate ranging and/or direction finding between two devices (one-to-one) and/or multicast (from one-to-many) and/or broadcast, (one to all) devices.
• the term “umeasf ' is used to indicate transmission of signals from a STA to a single device, whereas the term “multicast” is used to indicate transmission of signals from a STA to a pluralit of devices.
• the term “broadcast” is used to refer to transmission of signals from a STA to ail devices authorized to and/or capable of receiving the transmitted signal
• multiple antennas at the transmitter and receiver may be used to implement multiple input multiple output (MIMO).
• MIMO facilitates parallel delivery of multiple spatially multiplexed data signals, which are referred to as multiple spatial streams.
• an AP may simultaneously transmit to multiple client !IEs and beamforming may be used for directional signal transmission or reception.
• the tern "multiple transmit chains" may refer to the use of multiple transmit and/or multiple receive antennas,
• a data stream may be divided into multiple data streams, which are termed "transmit, chains.”
• the transmit chains may be spatiall multiplexed (e.g. sent through separate radio transmitters with distinct antennas). For example, each transmitter may include an antenna separated by a short distance from another antenna.
• Spatial multiplexin may facilitate operation of the transmitters on the same frequency.
• spatial multiplexing help distinguish individual transmit chains. For example, each chain may exhibit different multipath and/or other radio characteristics.
• the chains may be combined at the receiver to obtain the transmitted data stream,
• an AP may use a Hull Data Packet Announcement (NDPA), which may be immediately followed by a Null Data Packet (NDP) to determine how to direct a transmission.
• NDPA Hull Data Packet Announcement
• NDP Null Data Packet
• the NDP can be a physical layer (PHY) frame without data but with a known format and may be used to calibrate the channel.
• the UB(s) (receivers) receiving the NDP may respond with a * 3 ⁇ 4eamforaimg matrix", which provides some information about the channel.
• the information can be used by an AP (transmitter) to focus subsequent transmissions.
• Beaniforming matrices may not conventionally include information about Angle of Arrival (AoA), Angle of Departure (AoD), Azimuth, Channel Frequency Response (CFR), Channel Impulse Response (OR), Power Delay Profile (PDF), First Arrival Correction (FAC), and/or othe channel calibration metrics between
• the above information cannot typically be derived from information contained in a conventional beamforming matrix. Therefore, additional ranging/sounding message exchanges are often used to obtain the above information thereby increasing system overhead, and latency, which may adversely affect system performance metrics. Further, some ranging protocols (e.g. FTM) may be power and bandwidth inefficient due to a large number of message exchanges used for
• each device may perform positto ng channel calibration independently, traffic load may be increased substantially when several devices perform positioning/channel calibration,
• Some disclosed embodiments pertain to beamforming calibration techni ues, which facilitate improved UE location determination, and/or channel characterization. Further, disclosed embodi ments also facilitate the use of multiple transmit chains. For example, some disclosed embodiments may exploit the Null Data Packet (NDP) frame structure to facilitate utilization of multiple transmit chains.
• NDP Null Data Packet
• disclosed embodiments provide techniques for exchange of information between two communicating ST As including one or more of: Angle of Arrival (AoA), Angle of Departure (AoD), Azimuth, Channel Frequenc Response (CFR), Channel impulse Response (CIR), Power Delay Profile (PDP), First Arrival Correction (FAC), and/or other channel calibration parameters metrics, which are also referred to herein as "channel calibration parameters", “channel calibration metrics” or "channel
• the above channel calibration parameters me 'ics may be deterrnined and exchanged between eoramuaioating STAs with fewer frame exchanges.
• one or more of: frame structure, and/or information elements in frames, and/or message exchange protocols may be leveraged to determine and/or exchange calibration parameters mettics.
• Disclosed techniques may also be used to facilitate location
• the location determinatio may be based on one or more of the above channel calibration parameters.
• disclosed techniques may be embodied in an application on a U.E, which may direct a user to a shelf containing a desired product in a store.
• disclosed techniques may be used in surveillance cameras and/or drone navigation.
• the example message flows, frame formats, and/or information elements described herein may be compatible, in some respects with specifications, diagrams, and guidelines found in some 802.1 1 standards.
• AoA refers to a direction of propagation of a radio-frequency wave incident on an antenna array relative to orientation of the antenna array.
• AoA may he determined based on the Time Difference of Arrival (TDOA) or phase difference measurements of a radio wave received at individual elements of an antenna array.
• TDOA Time Difference of Arrival
• AoD Angle of Departure
• AoA and AoD may determined by a ST A based on signals exchanged with another STA. For example, a STA, soch as a recei er, may resolve AoA and AoD based on signals exchanged with another STA,
• An suitable technique may be used to estimate AoA mformaiion of frames received by a responder device and/or to estimate AoD infonnation for frames transmitted from a responder device.
• the responder device may use a number of different antenna patterns when estimating the AoA information of frames received from the initiator device. More specifically, when the responder device includes a number M > 2 antennas, the .responder device ma
• MUSIC Multiple Signal Classification
• ESPRIT Estimation of Signal Parameters using Rotational Invariance Techniques ' (ESPRIT); Matrix Pencil, etc.
• the terra CFR for an transmitting (Tx) antenna and a f h receiving Rx) antenna is also denoted by 3 ⁇ 4,(k) tor a tone k.
• the term CIR denoted by h ⁇ ri ⁇ refers to the inverse Fast Fourier Transform of the CFR, for the /* Tx antenna and a /* Rx antenna, in some embodiments, information exchanged between two communicating STAs may include a subset of information in the CIR (CIR ' ), which may capture the first arrival information.
• the length of C R' may be function of the accuracy of the estimation of first arrival information.
• Channel Feedback information CFl
• CFR Channel Feedback information
• Compressed Bearathnning (CBF) frame or another fmme may include a CFl field.
• the CFl field may include one or more of: Channel Frequency Response (CFR) information, or Channel impulse R esponse (CIR.) information, or a subset of the CIR mformarion with first arrival information, or Power Delay Profile (PDP) information, or First Arrival Correction (FAC) information.
• CFR Channel Frequency Response
• CIR. Channel impulse R esponse
• FAC First Arrival Correction
• the PDP is a measure of signal intensity received through a rm iipata channel as a function of tune delay.
• FAC time information facilitates greater .accuracy in the timing of communications between two STAs, which may improve quality in positioning applications.
• the term “downlink” refers to communication, which may occur in parallel from an AP to one or more UEs (transmitted by the AP), while the term “uplink” refers to communication, which may occur simultaneously, from one or more UEs to an AP (received by the AP),
• Disclosed techniques may also be used to facilitate location
• disclosed techniques may be embodied in an application on a UE, which may direct a user to a shelf containing a desired product in a store.
• disclosed techniques may be used hi surveillance cameras and/or drone navigation,
• station or "STA” may refer to a device with a Medium Access
• a STA may be viewed as a logical entity that is a singl addressable instance of a medium access control (MAC) and physical layer (PHY) interface to a wireless medium.
• a STA may take the form of a aon-AP STA, which refers to UE, includitig devices such as a mobile station, cellular phone, or a computing device such as a wearable device, laptop, handheld, tablet etc, or another entity coupled to the wireless network.
• A. STA may also take the form of an Access Point STA (AP STA), which refers to APs that provide wireless connectivity to one or more non-AP STAs.
• AP STA Access Point STA
• An AP S TA may be in communication with one or more non-AP devices and/or with other AP STAs.
• a STA may also be referred to as an "initiator'' or as a "respoiider” tor ease of explanation to distinguish from a STA that: initiates a sequence of events from a STA that responds to the initiated sequence.
• a "STA” may function as both an “initiator” and a "responder”. STAs may be mobile or stationary.
• a STA may also take the form of ''user equipment" (UE) or "mobile station* such as a DCluiar or other wireless communication device, personal
• UE is also intended to include devices which communicate with a personal navigation device (PND), such as by short-range wireless, infrared, wireline connection, or other connection - regardless of whether satellite signal reception, assistance data reception, and/or position-related processin occurs at the device or at the PND. In some instances, UEs may also serve as APs for other devices.
• PND personal navigation device
• UEs may also serve as APs for other devices.
• FIG. 1 shows a schematic block diagram illustrating certain exemplar features of a non-AP STA shown as UE 00 enabled to perform wireless
• UEIOO may take the form of a wearable user device, swell as a ristwatch, spectacles etc, where one or more functional components of UEiOO may be physically separate but operationally coupled to other functional components.
• displa 190 may be physically separate but operationally coupled processors) 150 and/or oilier functional units in UE1 0.
• UE100 (0 3$ ⁇ UE100 may, for example, include one or more processing units or
• UEIOO may also include a wireless network interface 105.
• wireless network interface may include transmitter 112 and receiver .1 14.
• UEIOO may further comprise
• UEI OO may take the form of a chipset, and/or the like. Further, UEIOO may optionally include a screen or display 1 0 capable of rendering images of various types.
• processors 150 may also receive input from transceiver I 10, which may receive wireless signals through one or more antennas 105 which may be used for signal transmission and reception using M1MO / MU-MIMO.
• Transceiver 1 10 may, for example, include a transmitter 112 enabled to transmit one or more wireless signals over one or more types of wireless communication networks and a receiver 114 to receive one or more signals transmitted over one or more types of wireless communication networks.
• transceiver i 10 may be capable of communication with a Wireless Local Area ' Network (WLA.N)., which may be based on IEEE 802.1.1 standards, Wireless Personal Area Network (WPAN), which miry be based on IEEE 802.15 standards and/or a Wide Area Network (WAN) based on-one or more cellular communication standards.
• WLA.N Wireless Local Area ' Network
• WPAN Wireless Personal Area Network
• WAN Wide Area Network
• Prooessor(s) 150 may be implemented using a combination of hardware, firmware, and software.
• processors) 150 may perform position determination and/or location assistance functions based on information deri ved from wireless .measurements by UEI0 either independently, and'or in conjunction with received: data or lneasuremetits from other ST As,
• processors) 150 may include transceiver 1 10, and/or other components as part of a single chip, integrated circuit, or package.
• Processors 1.50 may use some or all of the received signals and/or mformation to determine channel characterization information including Time
• position determination may be performed based, in part, on the channel characterization information and/or a variet of techniques described herein. For example, techniques including RTT measurements, TDOA, Reference Signal Time Difference (RSTD), Advanced Forward Link Trilateralation (AFLT), hybrid techniques. Received Signal Strength Indicator (RSSI) based measurements, and/or some combination of the abo ve may be used for position determination.
• TDOA Difference of Arrival
• RMSi Received Signal Strength Indication
• CFR CIR
• PDP. FAC etc.
• position determination may be performed based, in part, on the channel characterization information and/or a variet of techniques described herein. For example, techniques including RTT measurements, TDOA, Reference Signal Time Difference (RSTD), Advanced Forward Link Trilateralation (AFLT), hybrid techniques. Received Signal Strength Indicator (RSSI) based measurements, and/or some combination of the abo ve may be used for position determination.
• RSSI Received Signal Strength Indicator
• processors 150 may determine, record, and/or receive; tiffiestamps associated with a time of reception/arrival (TO A) and/or
• trarisrnissiori/departiiFe of signals, which may be used to determine RTT and/or a distance between UEIOO and one or more other devices.
• AoA, AoD, and other characteristics and parameters described herein may be used to determine or estimate a location micro-location of devices communicating with UEKK).
• the meastM ements and/or results obtained from measurements may be included in one or more frames exchanged between two ST As, such as between UE 100 and another device in accordance with one or more protocols described herein,
• the elements and methodologies ' described herein may be implemented by various means depending upon the application. For example, these elements and. methodologies may be implemented in .hardware firmware, software, or any combination thereof.
• the processors) 150 may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPCJAS), processors, controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, or a combination thereof.
• ASICs application specific integrated circuits
• DSPs digital signal processors
• DSPDs digital signal processing devices
• PLDs programmable logic devices
• FPCJAS field programmable gate arrays
• processors controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, or a combination thereof.
• the methodologies may be implemented using program code, microcode, procedures, functions, and so on that perform the functions described herein. Any machine-readable medium tangibly embodying instructions may be used in implementing the methodologies described herein.
• program code which may be stored in a non-transitory computer-readable medium 160 and/or memory 130, may be read and executed by processors) 150.
• Memory may be implemented within, processor(s) 150 or external to processor's) 150.
• memo ry refers to any type of long term, short term, volatile, nonvolatile, or other memory and is not to be limited to any particular type of memory or number of memories, or type of media upon which memory is stored.
• Memory 130 ma include, for example, a primary memory and/or a secondary memory .
• Primary memory may include, for example, a random access memory, read only memory, etc. While illustrated in mis example as being separate from rocessors) 150, it should be understood that all or part of a primary memory may be provided within or otherwise co-located/coopled with rocessors) 150, if
• the functions may be stored as one or more instructions or program code on a computer-readable medium, such as med3 ⁇ 4 3 ⁇ 4m .1 0 and/or secondary memory. Examples include computer-readable media encoded with computer programs and date associated with or used by the program.
• Computer-readable medium 0 includes physical computer storage media
• a storage medium may be any available medium that can be accessed by a computer.
• such non-transitory computer- readable media can comprise RAM, ROM, EEPROM, CD-ROM, flash memory, or other optical disk storage, magnetic disk storage or other magnetic storage devices, ot any other medium that can be used to store desired program code in the form of instructions and/or data arid that can be accessed by a computer;
• disk and disc includes compact disc (CD), laser disc, optica! disc, digital versatile disc (DVD), floppy disk and bio-ray disc where disks ' usually reproduce data ' magnetically, while discs reprodisce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
• the computer-readable medium including program code stored thereon may include program code to support wireless communication including unicast, broadcast, and wireless medium / channel characterization in a MU-MIMO environment in accordance with certain embodiments presented herein.
• the program code may further support wireless channel characterization, including sounding, ranging and/ r position determination.
• trie code may support one or more of AFLT / RTT / ' SSl / RSTD / TDOA /AoA / AoD, and other location determination techniques and/or channel characterization.
• instructions and/or data may be provided over a communication channel.
• a communication apparatus may include a transceiver 1 10, which may receive signals -through receiver 1 14 indicative of instructions and data.
• the instructions and data may cause one or more processors to implement wireless communication and/or wireless channel characterization (e.g. in a MU-MIMO environment), including ranging and/or position determination.
• the received instructions and data may also cause one or more processors to implement functions outlined herein.
• Fig, 2 s hows a simpli fied architecture of a wire less communication sysiem 200 in accordance with eertaisi embodiments presented herein.
• System 200 may include noa-AP ST As, which are shown in Fig. 2 as UEs 100-1 through 100-a
• UEs 100 may communicate over WLAN 230
• APs 240-1 through 240-4 may communicate with server 250 over WLAN 230
• system 200 illustrates a few UEs 100 and APs 240, the number of UEs 100 and APs 240 may be varied in accordance with various design parameters and ma include a smaller or larger number of UEs 100 and or APs 240.
• one or more UEs 100 aad/or APs 240 may comprise multiple antennas ami may support ⁇ , including MU- IMO.
• UEs 100 and APs 240 amy communicate over a
• WLAN network which may be based on IEEE 802. I f or compatible ' standards.
• UEs 100 and APs 240 may communicate using variants of the IEEE 802, 1 1 standards.
• UEs 100 an APs 240 may communicate using
• UEs 100 and APs 240 may communicate using some of the above standards, which may further support one or .more of Very High Throughput ( VHT) (as described in the above standards) and High Efficiency WLAN (HEW), and/or beamformihg with standardized sounding and feedback mechanisms.
• VHT Very High Throughput
• HEW High Efficiency WLAN
• UEs 100 and/or APs 240 may additionally support legacy standards for communication with legacy devices.
• UEs 100 and/or APs 240 may be connected with one or more additional -networks, such as a cellular carrier network, a satellite positioning network, WPA access points, and the like (not shown in FIG. 2), in some embodiments, UEs 100 and/or APs 240 ma be coupled to a wireless wide area network (WWA ) (not shown in Fig, 2),
• WWA wireless wide area network
• a WWAN may be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Access (TDMA) network, a Frequency Division Multiple Access iFDMA) network, an. Orthogonal Frequency Division
• CDMA Code Division Multiple Access
• TDMA Time Division Multiple Access
• iFDMA Frequency Division Multiple Access
• a CDMA .network may implement one or more radio access technologies (KATs) such as cdroa2000, Wideband-CDMA (W-CDMA). and so on.
• KATs radio access technologies
• Cdma200 includes IS-95, IS-20 0, and IS-856 standards.
• a TDMA network may implement Global System for Mobile Communications (GSM), Digital Advanced Mobile .Phone System (D-AMPS), or some other RAT.
• GSM, W-CDMA, and LTE are described in documents from 3GPP.
• Cdma20O0 is described i documents from a consortium named "3rd Generation Partnership Project 2" (3GPP2). 3GPP and 3GPP2 documents are publicly available.
• UEIOO may also communicate with server 250-1 through network 230 and.
• APs 240 which may be associated with network 230.
• UEIOO may receive and measure signals from APs 240, which may be used for position determination, la s nic embodiments, APs 240 ma form part of a wireless communication network 230, which may be a wireless local area network (WLAN).
• WLAN wireless local area network
• a WLAN may be an IEEE 802,1 lax network.
• AP 240 may be enabled to perform wireless communication (including unicasf, multicast, and broadcast) and wireless medium characterization.
• wireless communication and/or wireless medium characterization may be performed in a MU-MJMO environment in accordance with certain embodiments presented herein.
• UEI OO may serve as an AP 100.
• AP 240 may include, fo example, one o more processors) 350, memory 330, coupled storage 360, and transceiver 390, which may ' be operatlvely coupled with one or more connections 320 (e.g. , buses, lines, fibers, links, etc.).
• Transceiver 390 may be capa ble of communication with a Wirel ess Local Area Network (WLAN), which may be based on. the IEEE 802.11 standard (or variants thereof), Wireless Personal Area Network ( WPAN), which may be based o IEEE 802.15 and/or a Wide Area Network (WAN) based on one or more cellular
• WLAN Wirel ess Local Area Network
• WPAN Wireless Personal Area Network
• WPAN Wide Area Network
• transcei ver 390 may be coupled to one or more antennas 305, which ma be used for signal transmission and/or reception using M1MO / MU-M1MO. [ ⁇ 05?
• AP 240 may also interface with wired. networks through communications interface 380 to obtain a variety of network configuration related information, such as service set identifiers (SSlDs), basic service set
• Processor(s) 350 may use some or ail of the received information to generate CH, TDOA, RTF, RSSI, CFR, OR, PDF, Range, AOA, AOD, Azimuth, and oilier channel characterization information in accordance with certain with disclosed embodiments.
• f 00581 Proeessor s) 350 ma be implemented using ⁇ .-combin tion -o hardware, firmware, and software, or any combination thereof.
• the processing unit 950 may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable iogic devices (PLDs), field programmable gate arrays ' (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described, herein, or a combination thereof.
• ASICs application specific integrated circuits
• DSPs digital signal processors
• DSPDs digital signal processing devices
• PLDs programmable iogic devices
• FPGAs field programmable gate arrays '
• Any machine-readable medium tangibly embodying instructions may be used in implementing the methodologies described herein
• software may be stored in remo vable media drive 370, which may support the use of non-transitory computer-readable media 378, including removable media
• Program code may be resident on non-transitory computer readable media 378 and or memory 330 and may be read and executed by processors 350.
• the computer-readable medium including program code stored thereon may include program code to support wireless communication (including unicast, multicast, and broadcast), and or wireless medium characterization (including in a ⁇ / MU-MIMQ) environment in accordance with certain embodiments presented herein.
• Memory 330 ma be implemented within processors 350 or external to the processors 350.
• secondary memor may be operativety receptive of, or otherwise configurable to couple to.
• non-transitory computer-readable medium 378 As such, in certain, example implementations, the methods and or apparatuses presented herein may take the form in whole or part of a removable media drive 370 that may inc ude non-transitory computer readable medium 378 with computer implementabie instructions stored thereon, which if executed by at least one processing unit 350 may be operatively enabled to portions of the example operations including message flows and protocols described herein.
• Fig, 4 A shows an exemplary NDPA frame 400 with information pertaining to a subsequent NOP frame in accordance with certain embodiments presented herein, in some embodiments, NDPA frame 400 may take the form of an 802.1 !ac HDPA frame as defined in "Part 1 .1 : Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications " IEEE P802J l- EVmcTM/D5.0, Jan. 2016, Draft Standard for Information technology ⁇ Telecommunications and
• MAC Wireless LAN Medium Access Control
• PHY Physical Layer
• NDPA frame may include .Duration field 415, RA
• the NDPA frame contains at least one STA info field.
• NDP Announcement frame e.g. VHT
• NDPA includes more than one STA Info field 435, the RA field 420 of the NDP
• Announcement frame can be set to the broadcast address.
• Announcement frame includes a single STA Info field 435, the RA field 420 of the ' VHT ' NDP Announcement frame can be set to the M AC address of the VHT beamformee.
• the TA field may, for example, be set to the address of a STA
• the format of the Sounding Dialog Token field 430 is shown in Fig. 4B and includes Reserved subfieid 432 with a 2-bit length and Sounding Dialog token number subfieid.434,
• the Sounding Dialog Token Number subfieid in the Sounding Dialog Token field contains a value selected by the AP (heaofibrmer) to identify NDPA. frame 400.
• a first bit in Reserved subfield 432 may be used by the initiator to indicate to the respoiider ' tbat the immediately subsequent NDP is to be used for ranging
• a second bit in the Reserv ed subfiel 432 may be used to indicate symmetric ranging, to indicate that one side (e,.g. the initiator) is willing to share information, such as ranging information (e.g. captured and/or detemiined by the initiator).
• ranging information e.g. captured and/or detemiined by the initiator.
• portions of other information elements in NDPA frame 400 may be used to indicate: (i) that a subsequent NDP frame is to be used for ranging; and or (ii) that the initiator is willing to share ranging and/or other measured /determined channel characterization information.
• NDP frames which may be transmitted from multiple antennas, may be leveraged to determine AoA, AoD, and other parameters, in some embodiments, the AoA, AoD and other determined information may be included in an FTM frame thereb facilitating location determination, in some embodiments, by determining AoA, AoD, and RTT, a device may be able to determine its 3D location based on an exchange of FT frames with one other device with a known location thereby decreasing network traffic, lowering overhead, and/or facilitating quicker position determination.
• a STA requesting a specific raoging/soundiog or other operation may be termed an "initiator" of the operation.
• a STA responding to the ragging/sounding or other request may be termed a "Responder" of the operation.
• Figs. SA and 8 show an example Fine Timing Measurement (FTM) frame 500, which may include AoA, AoD, and/or other information in accordance with certain embodiments presented herein.
• FTM No Ack frame and FTM Ack i ames may take the form of FTM frame 500 with appropriate values of bits or fields in FTM frame 500. Accordingly, FTM frame 500 may be used in conjunction with the FTM, Ack, FTM No Ack, and FTM Ack message sequences / exchanges described herein,
• FTM .frame 500 may optionally include one or more of: FTM Synchronization information 5.18, LCI Report 520 field, Location SMS Report field 522. and Fine Timing Measurement parameters field 524, which may be of variable length. The above fields are defined in the WLAN MAC & PHY Specifications,
• Public Action 504 differentiates various Public Action frame formats, provides a mechanism for specifying various extended management actions.
• a value of 32 indicates an FTM Request while a value of 33 indicates an FT frame.
• Category 502 may specify a category of Public Action 504.
• a Category val ue of 2 ! may indicate VET,
• Dialog Token 506 may be a nonzero value chosen by a responding STA. to identify an FTM No Ack / FTM frame as the first of a pair, with a second or follow-up FTM frame to be sent later.
• the Dialog Token field may be set to 0 to indicate rise cod of the FTM session, fOO70
• the second or Mlow-up: FTM frame of the pair may use the nonzero value of Dialog Token 506 in the last transmitted FTM frame in Follow Up Dialog Token 508 to indicate that: (i) the current (second) FT / FTM Ack frame (of the pair) is a follow up FTM, and, (ii) TOD 510, TOA 512, TOD Error 514, and TOA Error 518 fields contain the values associated with timestamps captured with the first FT / FTM. No Ack frame of the pair.
• Follow Up Dialo Token 508 may be set to 0 to indicate that: (i) the current FTM /FTM No Ack frame is not a follow up; and (ii) TOD 510, TOA 512, TOD Error 51 , and TOA Error 518 fields are reserved.
• TOD and TOA fields may be expressed i units of picoseconds.
• jOOTlj in some embodiments.
• TOD 510 may include a timestarnp that represen ts the time, with respect to a time base, at which the start of the preamble of the last transmitted..FTM No Ack / FTM frame appeared at a transmit antenna connector of a transmitting STA.
• TO A 512 field may include a timestarnp that represents (he time, with respect to a time base, at which the start of the preamble of an FTM Ack / Ack frame to the last transmitted FTM. No Ack FTM. frame arrived at the receive antenna connector of a receiving STA.
• FTM Synchronization information 518 is present in the initial FTM. frame and in any retransmissions.
• Fig, SB shows the format of example AoA field 530
• Fig. 5C shows the- format of -example AoD field 540 accordmg to certain embodiments disclosed herein, la some embodiments, AoA field 530 may include Element ID 532, Letigth 534, and AoA information 548.
• AoD field may include Element ID 542,. Length 544, AoD information 548.
• die AoA Information may store values for Theia ...AoA and Phi AoA,, as described below, in Fig. 5E to indicate angle of arrival information of a specified frame, hi some
• the AoD field may store values for Th.eta_.AoD and Phi_AoD to indicate angle of departure information of the specified frame,
• die TQD field 510 may include 6 bytes
• the TOA field 512 may include 6 bytes
• the AoA field e.g. as a separate optional AoA field 530, or as part of FTM Parameters 524 ⁇ may include 5 bytes
• the AoD field 613 e.g. as a separate optional AoD field 540, or as part of FTM Parameters 524) may include 5 bytes ⁇ although for other embodiments, other field lengths ma be used).
• AoA field 530 may include AoA information 538 for frames exchanged during a ranging operation
• the AoD field 540 may include AoD information 548 for frames exchanged during the ranging operation.
• a responder may embed AoA information 538 into AoA field. 530 (or another
• FTM No Ack frame serving as an AoA field of FTM frame 500, and may embed AoD information 548 of the FTM frame into AoD field 540 (or another information element serving as an AoD field of FTM frame 500).
• the responder device may also embed TOA information into the TOA field 512 of FTM frame 500, and may embed TOD information of into the TOD field 510 of FTM frame 500.
• the responder STA may then use the FTM frame 500 as an FTM No Ack frame .ranging operations to transmit angle information (e.g., AoD and/or AoA) and time values to the initiator device.
• FTM No Ack frame may be compliant with existing
• FTM FTM No Ack
• FTM Ack FTM No Ack
• Element: ID field 542 may store a element ID value indicating that AoA field 530 includes AoA. information for a specified frame, while Length field.534 may store a value indicating- -a length (in bytes) of AoA field 530.
• Element ID field.542 may store an element ID value indicating that AoD fiekl 540 includes Ao ' D information tor a specified frame, while Length field 544 may store a value indicating a length (in bytes) of AoD field 540.
• FTM FTM No Ack frame 500 indicating that, a response may be sent as an FTM Acknowledgement (FTM Ack) frame
• FTM Ack FTM Acknowledgement
• a reserved bit in the FTM FTM N Ack frame 500 may be set to indicate to- a responder that a response with an FTM Ack frame is desired
• bit B15 570 of the Max TOA Error Field 56 may be used to indicate to a responder that a response with an FTM Ack frame is desired.
• the reserved bit e.g.
• bit B15 570 of the Max TOA Error Field 560) in an FTM No Ack frame 5(H), which, is used to indicate to a responder that a response with an FTM Ack frame is desired, is also referred to as an acknowledgment response bit herein.
• FIG, 5E is an example 3-dimensionai coordinate system 580 for representing the position of a STA using a. radius "r" and angles "theta ⁇ and "phi” ⁇ .
• ⁇ may be an angle with respect to the horizontal ( -y) plane, while 0 may be an angle with respect to the vertical (z) axis, ⁇ may range from 0° to 360*, while ⁇ may range from (V 3 to 180°.
• the radius r is the distance between the origin and a point coordinate (r, ⁇ , and tp) representing the location of a wireless device relative to the origin
• the AoA field may store values for 0_AoA and ⁇ __ ⁇ to indicate angle of arrival information of a specified frame.
• die AoD field may store values for 0_AoD and. ⁇ _AoD to indicate angle of departure information of the specified frame.
• FTM frame 500 which, in some embodiments, may take the form of a conventional FTM frame, in some embodiments, FTM frame 500 may include AoA, AoD and other information.
• FTM Measurement parameter 524, additional optional AOA and/or AoD fields, may comprise AoA, AoD, and/or other parameters.
• FTM Measurement Parameters 524 may be used to carry information pertaining to AoA, AoD, arid/or other parameters.
• FTM frame 500 is also referred to herein as an FTM No- Ack .frame/ [00811
• separate optional AoA and/or AoD fields m be provided in FTM frame 500.
• the AoA and/or AoD fields may carry AoA and/or Ao ' D information.
• FTM frame 500 may include other bits, fields etc to indicate when FTM frame 500 includes additioiiai information.
• the AoA, AoD, FT Ack and other information may be included in a manner so that legacy devices may continue to function normally.
• the responder device may be an access point STA
• the responder device may embed, into a beacon or other frame, information indicating whether the responder device is capable of including AoA and/or AoD information in one or more frames exchanged between the initiator device and the responder de vice.
• this information may be embedded within an information element (IE) or a vendor-specific infbnnatioo element (VSIE) of the beacon frame or other frame.
• IE information element
• VSIE vendor-specific infbnnatioo element
• FTM frame 500 may (alternatively or additionally) take the form of an FTM. No Ack or FTM Ack frame.
• FTM No Ack frame 500 may be set to indicate to a responder that a response with an FTM Ack frame is desired.
• the first 12. bits .of the AoA information field 538 may be used to indicate a value for 0_AoA
• the second 12 bits of the AoA information field may be used to indicate a value for ⁇ .. AoA
• the first 12 bits of the AoD information field 548 may be used to indicate a value for ⁇ AoD
• the second 12 bits of the A oD information field 548 may be used to indicate a value for ⁇ _ ⁇ .
• the 12-bit values tor ⁇ _ ⁇ . ⁇ . and 0 AoD may provide a resolution of approximately 0.044° (180° divided by (23.2 - 1 ) ⁇
• AoA and ⁇ ...AoD may provide a resolution of
• FTM frames formatted according to current FT protocols include a 6-byte TOD field 510 and a 6- byte TO A field 512 to store TOD and TO A information, respectively - e.g. to embed tiraestam values tt TOD and l3 ⁇ 4 TOA.
• t is the time of departure of a first frame
• 1 ⁇ 2 TOA is the- time of arrival of a corresponding response frame, where the first frame and corresponding response frame are used to measure RTT.
• RTT may be determined as (t? ⁇ - ⁇ TOD), where tj TOD is die time of departure of a first, frame, and t ? TO A is the time of arrival of a corresponding response/acknowledgment frame, where the first frame and corresponding response frame are used for ranging, including measuring .RTT.
• FIG. 6 shows an exemplary message flow 600 between a first STA ST I
• message flow 600 may be used for location determination and/or channel characterization. Fen- example, parameters related t a communication channel between first STA 1602 and one or more second STA2s 605 may be measured and/or determined using message flow 600. In some embodiments, message flow 600 may occur between a first STA I 602 (e.g. an AP) and a one or more second STAs STA2s 605, which are shown as STA2 1 604 . , , STA2J 608 . . . STA2J- 60? . . . STA2_z 606, where I ⁇ k ⁇ z and 1 ⁇ JC ⁇ z,
• one or more of STA2s 605 may use subscription message flow 60S (and/or a subscription protocol 608) to subscribe to be polled by first STA 1 602.
• the polling may be related to location determination, and/or FTM, and/or for othe channel characterization purposes.
• T STAl 602 may be configured (e.g. through subscription and or another mechanism) with subscription or polling list that includes one or more of STA2s 605.
• the polling list in STA 1 602 may specify an order to poll one or more subscribing STA2s 605 that form a subscription group relative to STA I 602.
• STA2_I 604 and STA2j? 606 may form part of a subscription group.
• STA2J 604 and STA2_ 606 may subscribe to be polled by an AP (e.g. STA 1 602) for ranging, location determination, channel characterization, and/or compu iation offloading. j3 ⁇ 4687
• STA ! 602 may poll one or more subscribing
• a TXOP enables a ST A to transmit multiple frames consecutively in a burst after acquisition of a commun cation channel.
• STAI 602 may perform ranging with a group of one or .more. subscribing STA2s 605 in a single TXQP thereby limiting overhead.
• Sounding TXOP 610 may be used to perform ranging with STA2_! 604, STA2_z 606 and any other subscribing STA2s.
• STAi 602 may group one or more subscribing STA2s 605 by a delivery traffic indication map (DTIM) or using Target Wake Times (T Ts) etc. thereby decreasing the overhead per unit time imposed by ranging,
• DTIM delivery traffic indication map
• T Ts Target Wake Times
• ST A 1 602 may broadcast an
• NDPA frame 61.4 may indicate that STA2J
• NDPA frames may identify one or more STA2s 705 to listen to a subsequent NDP frame. NDPA frames may also include information about the subsequent NDP frame, including the size of the NDP frame, which may depend on the number of antennas and spatial streams itsed. fay the transmitting STA (e.g. STA I 602),
• ⁇ 0090 NDPA frame 14 may be received fay STA2 J 604 at time T2_l 6 i 6, and by other STA2s at various respective local reception times.
• the time TI 612 of transmission of NDPA frame 614 may be recorded by STAI 602.
• the times of reception T2 x of NDPA frame 614 may be recorded by respective receiving STA2 x 607 (1 ⁇ A * ⁇ z).
• S TA2 I 604 may record the time of reception T2J 616 of NDPA frame 614.
• NDP frame 620 may broadcast an NDP frame 620.
• the time of transmission TI ' 618 of NDP frame 620 may be recorded by STAI 602.
• NDP frame 620 may be received by STA2__ 1 604 at time T2' J 622, The time In general, NDP frame 620 may be received by stations STA2jt 607 at respective local reception times T2'_x 627. The times of reception T2'_x 6.27 of NDP frame 620 may be .recorded by respective receiving STA2_.* 60? (I ⁇ x ⁇ z). For example, for 1, STA I 604 ma record the time of reception T2' __ 1 622 of N DP frame 620.
• NDPA, frame 614 and/or NDP frame 620 may be broadcast by STAI 602 using multiple antennas, la some embodiments, one or more non-subscribing STA2s 605, (e.g. some non-subscribing STA2_& 608) may be able to leverage a broadcast NDP for independent one-sided computation of location and/or determination of other channel calibration metrics, in some embodiments, STA2s 705 receiving the NDP frame 720 may compute channel chameterization.
• AoA Angle of Arrival
• AoD Angle of Departure
• FTM No Ack _1 frame 626 may be transmitted by FTM No Ack _1 frame 626.
• FTM No Aek _ frame 626 may be received by STA 1 602 at time T4 ⁇ J 624.
• the time T3' 1 628 of transmission of FTM No Ack 1 frame 626 may be recorded by STA2_1 604,
• No Ack J frame 626 at STA 1 602 may be recorded by STA 1 602.
• FTM No Ack 1 frame 626 may include information pertaining to one or more times T2J 616 (reception of NDPA frame 614 at STA2..1 6(34), T2' 622 (reception of NDP frame 620 at. STA2_i 604), and/or T3 628 (time of transmission of FTM No Ack_.l frame 626 by STA2J. 604).
• FTM No Ack_. « frame, 1 ⁇ x ⁇ z may be an FTM frame, which may include CF1 and/or AoA and/or AoD, and/or other channel characterization information, as measured by STA2 604.
• F M No Ack J frame 626 (and/or FTM No Ack_x frame 632 ) may further have acknowledgment response bit set. to indicate to STA i 60 that a conventional "Ack" frame response to FT No Ack .1 irame 626 (and/or FTM No Ack frame 632) is not desired or requested.
• FTM No AckJ On receiving FTM No AckJ.
• STA 1 602 may have sufficient information to perform channel characterizatio including ranging and/or determining a location ofSTA2 604,
• STAI 602 may unicast, multicast, or broadcast .Po!lje frame 630, Polijs frame 630 may meinde an indication that some subscribing STA2jr is being polled, where ⁇ x ⁇ z.
• Po Vx frame 630 may include channel cha cterization im3 ⁇ 4rmatioa, including the range and/or AoA and/or AoD information of the immediately preceding polled STA2 (.r- 1), For example, for x ;;: 2, Poll (.v ::: 2/ frame may include channel characterization information for STA2Jx-l) ⁇ STA2_1 604as measured or determined by S f A l 602.
• Poll je frame 630 when Poll je frame 630 is broadcast or multicast, information pertaining to STA2_(x -!.), which may be included in PoUje frame 630 may be rendered inaccessible or ' unintelligible to some other STA2& 605 that may receive Poll A- frame 630, For example, encryption and/or other privacy/security mechanisms may be used to prevent unauthorized access to information intended for some specific
• STA2jr may respond to Pol v frame 630 with
• FTM No Ack jr frame 632 may have
• FTM No Aekjc frame 632 may be received by STA.l 602 at rime T4'jt 634. The time of reception of FTM No Ack J frame 634 may be recorded by STA1 602, As outlined above, FTM No Ack_x frame 634 may include timing information such as reception times of NDPA. frame 14, NDP frame 620 at STA2_x 607, as well as CFI and/or AoA and/or AoD, as measured / determined by STA2_x 607. On receiving FTM No Ack / frame 632 STAI 602 ma have sufficient information to perform ranging and/or determine a location, for STAjc 607.
• PoH * 630 and FTM No Ackjr. 632 sequence may continue for plurality of APs in the subscription group, where x may be appropriately incremented if there are other subscribing STA2s.
• Poll 630 and FTM No Ack x 632 sequence may iterate until subscribing STA2s have been polled. For example, in Fig. 6, the sequence may continue until STAI 602 transmits Poll_-T frame 635 to S A2_2 606 at time T4'_j?
• FTM No Ack _z frame 637 which may include timing information such as reception times of NDPA frame 614, NDP frame 620 at STA2 ignore z 606, as well as CFI and/or AoA and/or AoD, as measured. / determined by STA2_z 606.
• a "dummy" Poll ' frame 636 may be used to indicate he end of sounding TXOP 610. 1» so me embodiments, .PoU_y frame may be used to indicate the end of a Poll x 630 and FTM " No Ack x 632 sequence and or TXOP 610.
• Foil v frame 636 may additionally or alternatively include information determined by STA 1 602 from an immediately preceding FTM No Ack frame received prior to transmission of Poll j' frame 636,For example, if the immediately preceding FTM No Ack frame prior to termination of TXOP 61 was FTM No Ack_2 frame 63? transmitted by ST.A2 z 606, then, Pol! v frame 63 may include channel characterization information pertaining to STA2 z 606 measured/determined from FTM No Ackjr frame 637.
• STA1 602 may compute AoA/AoD and/or channel characterization information based on as immediately preceding FTM No Ackjfx- ⁇ /F M No Ack z frame received from a subscribing STA2 / STA2 z 606 and share this via the next Poll..* 630 / Poll v 636 frame transmitted by STA! 602 during the same TXOP (e.g. TXOP 610).
• TXOP e.g. TXOP 610
• STA2 ! 604 and'or STA . z 606 may separately contend for new TXOP2 64 and request STA! 602 for last measured / determined channel characterization information from a corresponding FTM No Ack_l frame 626 and/or FTM No Ackj? frame 637, respectively.
• STA2 1 604 may contend for TXOP2 640 and request, infommtion measured from and/or determined, based on frame 626.
• STA_2606 may contend for TXOP2 640 and request information measured from and/or determined based on FTM No Ack j: frame 637.
• message flow 600 may include multiple TX ' OPs following sounding TXOP 610.
• the NDPA frame 614 may specify a dialog token for the transaction, which may be referenced by STA2 x 607 (1 ⁇ x ⁇ z,) when requesting a new TXOP2 640 using Requesiinfo frame 642 transmitted at time T3" 644.
• STA1 602 may respond to Requesiinfo frame 642 using ' Resplttfo frame 646 to send measured /determined, information from correspondin FT Ho Ackje 632 frame to requesting STA2_ 607.
• Respinfo frame 646 may also- include the dialog token referenced in corresponding Requesiinfo frame 642.
• STA2_ 60? may record the time of transmission T3" x. of Requesiinfo frame 642 by STA2 x 607.
• STA l 601 may record the time of reception T4"_x of Requestinfo frame 642 at STAl 602.
• one OF more imassoeiated/unafiliiated STA2s 605 (such as some ST A2 J 608) which may not be subscribed to a STAl 602 subscription group may be able to leverage new TXOP2 640 using the Requestinfo frame 642.
• STA2 Jc 60S may use Requestinfo frame 642 to request measured / determined channel characterization information, to some embodiments, legacy STA2s, ⁇ which may not support soundin .protocol 610 may also leverage T.XOP2 640 to obtain measurements and or complete a message exchange with STAl 602.
• Requestinfo frame 642 transmitted by an unaffiliated and/or legacy STA2_£ 608 during TXOP2 640 with the dialog token may be received by STAl 602 at time T4" 645.
• the time of transmission T3"Jk 644 of Requestinfo frame 642 may be recorded by S A2 Jc 608.
• Requestinfo frame 642 may include a time T2'Jc at which NDP frame 620 may have been received.
• the time of reception T4" k 645 of Reqaest o frame 642 may be recorded by STAl 602.
• ST l 602 may respond to STA2_£ 608 and Requestinfo frame 642 with Respl ' nfo frame 646, Respinfo frame 646 may include the time of reception T4" Jk 645 of Requestinfo frame 642 In some embodiments, Resplnfo frame 646 may also include the dialog token referenced in Requestinfo frame 642.
• both STAl 602 and one or more STA2s 605 may have information sufficient for ranging and/or location determination.
• Fig, 7 shows an exemplary message flow 700 to facilitate location determination between a first STAl 702 (e.g. an AP) and a plurality of other ST As, shown as STA2 704 , . . STAjfc . , . ST Ax 707 . . . STAz 706, where 2 ⁇ k ⁇ z in a WLAN environment supporting uplink multiuser capabilities such as Uplink MU- ⁇ , in some embodiments, message flow 700 may be used for location
• message flow 700 may occur between a first STA 1.702 (e.g. an AP) and one or more other second STA2s 705, which are shown as S A2J 704 , . . STA2Jfc 708 . . , STA2jc 707 . . . STA2_z 706, where 1 ⁇ k ⁇ z and 1 x ⁇ z.
• message flow 700 may use
• Orthogonal Frequency Division Multiple Access OFDMA
• UL MU-MIMO uplink multi-user MJMO
• one o more of ST A2s 705 may use subscription message flow 70S (and/or a. subscription protocol 708 ⁇ to subscribe to be polled by first STA ! 702.
• STAl 702 may be configured (e.g. through a subscription protocol and/or another mechanism) with a subscription or polling list including one or more of STA2s 705.
• STA2_ 2 706 may form part of a subscription group, hi one embodiment, STA2_1 704 and STA2_z 706 may subscribe to be polled by an STA1 702, which may be an AP STA, for ranging, location determination, channel eharaeterization, and/or computation offloading.
• STA1 702 may be an AP STA, for ranging, location determination, channel eharaeterization, and/or computation offloading.
• Subscribing STA2s 705 may be polled in a single TXOP,- or in multiple
• STA I 702 may perform ranging with a group of STAs in a single TXOP thereby limiting overhead. For example. Sounding TXOP 7 i 0 may be used to perform, rangin with STA2 1 704, STA2_ 706 and other STAs. In some embodiments, STA! may group STAs by DT! and/or TWTs etc. thereby decreasing the overhead per unit time imposed by ranging,
• STAi 702 may broadcast NDPA frame 714.
• NDPA frame 714 may indicate that one or more subscribed STA2s 705 and/or a group ofSTA2s are being polled.
• the time of transmission of NDPA frame 7.14 may be recorded by STA.l 702,
• the times of reception of NDPA feme 714 may he recorded by the respective receiving STA2s 705.
• jOOltOj At time T! 712, following the broadcast of NDPA frame 714, STA 1 702 may broadcast NDP frame 720.
• the time of transmission Tl 712 of NDP frame 720 may be recorded by STAI 702, NDP frame- 720 may be received by STA 2_ I 704 a time ⁇ 2_1 716.
• NOP frame 720 may be received by stations S.TA2 x 707 at respective local reception times 12 7,1 , where 1 ⁇ x ⁇ z.
• the times of reception of NDP frame 720 may be recorded by respecti ve receiving stations S A2 .v 707,
• STA2_1 704 may record the time of reception T2 _1 716 ofNDPA frame 7.14.
• NDPA frame 614 and/or NOP ftams 620 may be broadcast by STAi 602 using multiple antennas.
• STA2s 705 receiving the NDP frame 720 may compute channel characterization metrics including Angle of Arrival (AoA) and/or Angle of Departure (AoD) following reception of the NDP. Computation of AoA / AoD are one-sided computations and may be performed locally at each STA2 705 receiving
• AoA Angle of Arrival
• AoD Angle of Departure
• non subscribing STAs may be able to leverage a broadcast ND for independent one-sided computation of location/ channel characterization metrics (e.g.: AoA),
• a t time Tl * 718, following the transmission of NDP frame 720, ST A I 602 may broadcast trigger frame 726.
• the time of transmission Tl * 7.18 of trigger frame 726 may be recorded by STAI 702.
• Trigger frame 726 may be received by STA2_1 704 at time T2'_ l 728.
• STA2_,v 707 receiving trigger frame 726 may determine 2'jr on receiving trigger frame 726.1n general, trigger frame 726 may be received by stations STA2_x 707 at respective local reception times T2'_x 727, where 1 ⁇ x ⁇ 2.
• STA2 1 704 may transmit FTM No Ack J frame 730, which may be received by STA I 702 at time T4*_J . 724, FTM No AckJ frame 730 may include channel characterization, information for the communication channel between. STAI 602 and STA2 J 704. in some embodiments, FTM No Ack 1 frame 730may have acknowledgment response bi t set,
• the SIFS interval is a range of time duration values for which are provided by relevant IEEE 802,.1 1 standards.
• the SIPS interval may, for example, specify a time to transition from a receive mode (e.g., to receive a request or other frame) to a transmit mode (e.g., to transmit an acknowledgment or other frame) or vice versa, jOOltSj In genera!, FTM No Ack frame 734 may be transmitted from STA r 707 at a time T3' perennial . « after a SIFS time interval following the end of reception (at STA2_ 707) of trigger frame 726, The titties of transmission T3'jr 737 of the FTM No Ack frame by respective stations STA2 x 707 may be recorded by STA2_x 707.
• FTM No Ackjc frame 734 may include channel characterization informatiori for the
• FTM No Ack A " frame 734 may have acknowledgment response bit set. jOOl 16] The time of reception T4' A" 736 (at STAI 702) of a respective
• STAI 704. For example, forx -l , at STAI 702, the time of reception T4'_l 724 ofFTM-ACKJ frame 730 from STA2J. 704 may be recorded.
• the FTM No_Ack_x frames 734 may be multiplexed, using Orthogonal Frequency Division Multiple Access (OFDMA) or uplink multi-user MIMO (lit MU-MIMQ).
• ST A 1 702 may receive FTM No Ack frames from all responding STA2s 705 either: (a) simultaneously, or (b) within a SIFS interval from the end of transmission of trigger frame 726, or (c) in ciose temporal proximity (i.e. by some designated or requested time) . and/or (d) within some time interval of transmission of trigger frame 726, Upon recei ving the FTM- ACK. frames, STAI 602 may have timing information to perform ranging, location determination, and/or channel characterization,
• FTM-INFO or FTM Ack frame 738 may include timing, ranging and/or channel characterization measurements for all responding STA2s 705 that may be part of a subscription group, hi some embodiments, FTM-INFO /FTM Ack frame 738 may include measurements for one or more STA2s in a subscription group.
• informatiori pertaming to one or more STA2s may be rendered inaccessible or unintelligible to other STAs that may receive FTM-INFO frame 738 hot are not
• encryption and/or other privacy/securit mechanisms may be used to prevent unauthorized acces to information intended for a first STA by a second STA,
• STA2_£ 708 (and/or another STA2_ x 707) may separately contend for anew TXOP2 740 and request STAI 702 for measured / determined channel characterization information, in some embodiments, the measured / determined, channel characterization information may be requested using Requestlnfo frame 742.
• Requestlnfo frame 742 may be transmitted STA2 J. 708 (and/or another STA2.
• X 707 ⁇ at time T3" 744, Time T3" 744 may be recorded by STA2_& 708,
• STA2_£ 708 may be one of STA2s 705 that may not be part of the subscription list on STAI 602 and/or a legacy STA2 that ma not support toe protocol outlined in sounding TXOP 710.
• STAI 702 may record the time of reception T4"745 of Requestlnfo frame 742, in some embodiments.
• Requesting frame 742 may include time T2 _k at which NOP frame 720 may hav been received by STA2_ - 70S.
• the NDPA .frame 714 may specify a dialog token for (be transaction, which may be referenced by STA2je 707 or STA2 k 708 when requesting a new TXOP2 740 using Requestlnfo frame 742.
• a subscribing STAlje 707 may contend for TX0P2 740 and request information measured from and/or determined based on FTM No Ackjc frame 734 using Requestlnfo frame 742, which may include a dialog token specified in NDPA frame 714,
• a subscribing STA ' 2 x 707. may contend for TXOP2 740 and request information measured by STAI 702 in relation to Requestlnfo frame 742 transmitted by STA2jc " 07.
• STA 1 702 may respond to Requestln.ro frame 742 in TXOP2 740 using Resplnfo frame 746, which may also include the dialog token referenced in corresponding Requestlnfo • frame ' 742.
• Resplnfo frame 74 may include measured /determined, information related to a corresponding Requestlnfo frame 742 such as the time of reception T4" 745 of corresponding Requestlnfo frame 742 and/or other channel characterization information measured/determined by STA.l 702.
• Resplnfo frame 746 may include time T4" 745 and/or other measured /determined information related to a corresponding Requestinfo frame 742 for an uuaffiiiated/legacy STA2Jt 708 or another STA2_x 707.
• Resplnfo frame 746 may include measured /determined information related to FTM No Ack A: 734, which may have been requested by STA2 x 704 using a Requestinfo frame 742 that referenced a dialog token.
• Resplnfo frame 746 may also mclude the dialog token referenced in a corresponding Requestinfo frame 742.
• legacy STA3 ⁇ 4 which, may not support sounding protocol 10 may also leverage TXOP2 640 to obtain measurements and/or complete a message exchange with STA i 602 using the
• Requestinfo 742 and Resplnfo 746 message sequence in TX0P2 740.
• both STA 1 702 and one or more STA2s 705 may have information sufficient for ranging and/or location determination
• Fig. $ shows a timeline 800 of events associated with the message flow sequence in Fig. 7.
• DPA frame 714 may be broadcast at time 805, followed by broadcast of NDP frame 720 at time Tl 7.12.
• Trigger frame is broadcast at time TV 718 and a following a SIFS time interval after reception of trigger frame 726, STA2 704 (beamformee 1), STAz 706 (beamibrmee 706), and STAx 707 (beamionnee x) send out FTM-ACK frames 730, 810, and 734, respectively,
• STA i,STA2.,S Ax or some subset of the STAs may be additionally be APs or other wall powered devices that ma periodically perform message exchanges, such as those outlined above in relation to Figs. 6-8, to facilitate passive positioning / channel characterization by other STAs in the vicinity to determine their respective locations.
• Fig. 9 shows an exemplary flo wchart 90 of a method for ranging, and/or direction finding, and/or location determination according to disclosed embodiments.
• method 900 may be performed by an STA (e.g. STA 602 or STA 702).
• the STA may take she form of AP STA (e.g. AP 240), or a non-AP STA (e.g. IJE .1 0).
• method 900 may be embodied as instreetions on computer-readable medium,, which, may be executed by a processor coupled to STA.
• NDPA Announcement Announcement
• STA.i first STA
• STA2- second STAs
• i ⁇ / ⁇ /Vand /V> i.
• the first STA STA ' i may broadcast, subsequent to the first NDPA f ame, a Null Data Packet (NDP) frame from a plurality of antennas on the first STA STAL
• NDP Null Data Packet
• the first STA STA ' I may receive, is response to the NDP frame,, or a Trigger frame broadcast subsequent to the NDP .frame, one or more corresponding first Fine Timing Measurement (FTM) frames FTM-A': from the one or more second STAs STA2-;, where i ⁇ k ⁇ j.
• FTM Fine Timing Measurement
• each corresponding first FTM frame FTM-A (a) may be received from a distinct corresponding second STA $TA2'k of the one or more second STAs STA.2-/; and, (b) may comprise corresponding first ranging measurements between the first STA STA 1 and the corresponding second STA STA2 - as determined by the corresponding second STA STA24" based, in part, on the NDP frame.
• the first STA STA land the one or more second ST As S A2- may form part of a subscription gro up.
• each corresponding first ranging measurement comprise at least one of: Angle of Arrival (A A) information of wireless signals from the first STA STA " !
• the one or more corresponding first FTM frames FTM-A may be received (e.g. in block 930) in response to a previously transmitted trigger frame, and encoded using Orthogonal Frequency Division Multiple Access, (OF.OMA).
• the trigger frame may be broadcast by the first STA STA 1 to the one or more second STA2-; subsequent to the broadcast of the NDP frame.
• the one or mote corresponding first FTM frames FTM-& may be received within a Short Inter Frame Spacing fSIFS) time interval from the end of transmission of the trigger frame.
• a set of second ranging measurements may be determined based in part, on the one or more corresponding first FTM frames FTM - received by the .first STA STA I; and the first STA STA ! may broadcast, in response t the one or more corresponding first FTM frames FTM-&, at least one additional frame.
• the at least one additional frame may comprise a subset of the second ranging measurements.
• the communication above including broadcast of the DPA frame, broadcast of the NDP frame, reception of first FTM frames FTM- ⁇ , and broadcast of the at least one additional frame
• TxOP single transmission opportunity
• the first STA STA i may receive, at least one request for a subset of the second ranging measurements, the request referencing a dialog toketi associated with the NDP frame; and may transmit a response to the at least one request comprising the requested subset of ranging measurements, wherein the response references the dialog token.
• the at least one request for the subset: of second ranging measurements may be recei ved subsequent to the TxOP above during which the communication occurs.
• jOO 135 in some ' embodiments., receiving the one or more .corresponding first Fine Timing Measurement (FTM) frames FTM-& (e.g.
• hi block 930) may comprise; receivin an initial corresponding first FTM frame F ' TM-1 (k-l) from a corresponding initial STA STA2-1 (k ⁇ .) in the one or more second STAs STA2 " transmitting, upon, reception of the initial corresponding first FTM frame FTM- 1 , one or more poll frames Poll Jc, each of the one or more poll frames identifying a distinct subsequent second STA STA2-&, in the one or more second STAs STA2-A', k > 2, ; and recei ving, in response to each poll frame Po!i_.i, a corresponding subsequent .first FTM frame FTM-A", k > 2.
• each of the one or more poll frames Pol l k > 2 may farther comprise: a corresponding second ranging measurement based, in part, on an immediately preceding corresponding first FTM frame FTM-(/;- ⁇ ) received by the first STA STA ⁇ 100-1 prior to transmission of the poll frame Poll J;,
• the communication above including broadcast of the NDPA frame, broadcast of the NDP frame, reception of one or more first FT frames FT -A', and transmission of poll frames Poll may be performed during a single transmission opportunity (TxOP).
• a set of second ranging measurements may be determined based, in part, on the one or more corresponding first FTM frames FTM-A ; received by the first STA STAi 100-1. Further, at least one request for a subset of the second ranging measur me ts may be received by the first STA STA 5 100- 1 , where the request references a dialog token associated with the NDP frame; and in response to the at least one request, the first STA STAj 100-1. may transmit the requested subset of ranging measurements, wherein die response references the dialog token,

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