EP4348855A1 - Variation d'un débit de déclenchement de transmissions mimo à partir de dispositifs de communication sans fil - Google Patents

Variation d'un débit de déclenchement de transmissions mimo à partir de dispositifs de communication sans fil

Info

Publication number
EP4348855A1
EP4348855A1 EP22809989.1A EP22809989A EP4348855A1 EP 4348855 A1 EP4348855 A1 EP 4348855A1 EP 22809989 A EP22809989 A EP 22809989A EP 4348855 A1 EP4348855 A1 EP 4348855A1
Authority
EP
European Patent Office
Prior art keywords
wireless communication
communication device
network
messages
rate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22809989.1A
Other languages
German (de)
English (en)
Other versions
EP4348855A4 (fr
Inventor
Christopher Beg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cognitive Systems Corp
Original Assignee
Cognitive Systems Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US17/328,479 external-priority patent/US11570712B2/en
Application filed by Cognitive Systems Corp filed Critical Cognitive Systems Corp
Publication of EP4348855A1 publication Critical patent/EP4348855A1/fr
Publication of EP4348855A4 publication Critical patent/EP4348855A4/fr
Pending legal-status Critical Current

Links

Classifications

    • 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
    • H04B7/0413—MIMO systems
    • 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
    • G01S13/003—Bistatic radar systems; Multistatic radar systems
    • 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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/003—Transmission of data between radar, sonar or lidar systems and remote stations
    • G01S7/006—Transmission of data between radar, sonar or lidar systems and remote stations using shared front-end circuitry, e.g. antennas
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0027—Scheduling of signalling, e.g. occurrence thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave using a pre-established activity schedule, e.g. traffic indication frame
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0225—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal
    • H04W52/0229—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal where the received signal is a wanted signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0225—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal
    • H04W52/0235—Power saving arrangements in terminal devices using monitoring of external events, e.g. the presence of a signal where the received signal is a power saving command
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0261—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level
    • H04W52/0274—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level by switching on or off the equipment or parts thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0261—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level
    • H04W52/0274—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level by switching on or off the equipment or parts thereof
    • H04W52/028—Power saving arrangements in terminal devices managing power supply demand, e.g. depending on battery level by switching on or off the equipment or parts thereof switching on or off only a part of the equipment circuit blocks

Definitions

  • MIMO multiple- input/multiple-output
  • Motion detection systems have been used to detect movement, for example, of objects in a room or an outdoor area.
  • infrared or optical sensors are used to detect movement of objects in the sensor’s field of view.
  • Motion detection systems have been used in security systems, automated control systems and other types of systems.
  • FIG. 1 is a diagram showing an example wireless communication system.
  • FIGS. 2A-2B are diagrams showing example wireless signals communicated between wireless communication devices.
  • FIG. 2C is a diagram of an example wireless sensing system operating to detect motion in a space.
  • FIG. 3 is a diagram showing an example PHY frame.
  • FIG. 4 is a diagram showing an example PHY frame.
  • FIG. 6 is a diagram showing example frequency spectra of wireless signals.
  • FIG. 7 is a diagram showing an example representation of the Open System Interconnection (OSI) model.
  • OSI Open System Interconnection
  • FIG. 8 is a diagram showing example message components for three layers of a typical OSI model.
  • FIG. 9 is a flowchart representing an example process that finds an upper layer logical address.
  • FIG. 10 is a state machine diagram representing an example process that elicits MIMO transmissions from wireless communication devices.
  • FIG. 11A shows a flowchart representing an example process to setup an ICMP ping.
  • FIG. 11B shows a flowchart representing an example process to stop an ICMP ping.
  • FIG. llC shows a flowchart representing an example process to conduct an ICMP ping.
  • FIG. 12A shows a flowchart representing an example process to setup a TCP Ping.
  • FIG. 12B shows a flowchart representing an example process to conduct a TCP Ping.
  • FIG. 13 shows a flowchart representing an example process to setup an ARP Ping.
  • FIG. 14 shows a flowchart representing an example method of eliciting MIMO transmissions from wireless communication devices.
  • FIG. 15 is a block diagram showing an example wireless communication device.
  • FIG. 16 shows an example exchange of messages in an association process between a client device and an access point device.
  • FIG. 17 shows an example traffic indication map (TIM) element.
  • FIG. 18 shows an example MAC header having a frame control field.
  • FIG. 19 shows an example format of a power saving poll message.
  • FIG. 20 shows an example control loop that can be used to vary the rate at which transmissions are elicited.
  • FIG. 21 shows a flowchart representing an example method of varying a rate of eliciting MIMO transmissions from wireless communication devices.
  • a wireless sensing system can process wireless signals (e.g., radio frequency signals) transmitted through a space between wireless communication devices for wireless sensing applications.
  • Example wireless sensing applications include detecting motion, which can include one or more of the following: detecting motion of objects in the space, motion tracking, localization of motion in a space, breathing detection, breathing monitoring, presence detection, gesture detection, gesture recognition, human detection (e.g., moving and stationary human detection), human tracking, fall detection, speed estimation, intrusion detection, walking detection, step counting, respiration rate detection, sleep pattern detection, apnea estimation, posture change detection, activity recognition, gait rate classification, gesture decoding, sign language recognition, hand tracking, heart rate estimation, breathing rate estimation, room occupancy detection, human dynamics monitoring, and other types of motion detection applications.
  • detecting motion can include one or more of the following: detecting motion of objects in the space, motion tracking, localization of motion in a space, breathing detection, breathing monitoring, presence detection, gesture detection, gesture recognition, human detection (e.g., moving and stationary human detection),
  • wireless sensing applications include object recognition, speaking recognition, keystroke detection and recognition, tamper detection, touch detection, attack detection, user authentication, driver fatigue detection, traffic monitoring, smoking detection, school violence detection, human counting, metal detection, human recognition, bike localization, human queue estimation, Wi-Fi imaging, and other types of wireless sensing applications.
  • the wireless sensing system may operate as a motion detection system to detect the existence and location of motion based on Wi-Fi signals or other types of wireless signals.
  • home monitoring using the wireless sensing systems described herein may provide several advantages, including full home coverage through walls and in darkness, discreet detection without cameras, higher accuracy and reduced false alerts (e.g., in comparison with sensors that do not use Wi-Fi signals to sense their environments), and adjustable sensitivity.
  • Wi-Fi motion detection capabilities By layering Wi-Fi motion detection capabilities into routers and gateways, a robust motion detection system may be provided.
  • the examples described herein may also be useful for wellness monitoring. Caregivers want to know their loved ones are safe, while seniors and people with special needs want to maintain their independence at home with dignity.
  • wellness monitoring using the wireless sensing systems described herein may provide a solution that uses wireless signals to detect motion without using cameras or infringing on privacy, generates alerts when unusual activity is detected, tracks sleep patterns, and generates preventative health data.
  • caregivers can monitor motion, visits from health care professionals, and unusual behavior such as staying in bed longer than normal.
  • motion is monitored unobtrusively without the need for wearable devices, and the wireless sensing systems described herein offer a more affordable and convenient alternative to assisted living facilities and other security and health monitoring tools.
  • the wireless sensing systems described herein use predictive analytics and artificial intelligence (AI), to learn motion patterns and trigger smart home functions accordingly.
  • smart home functions that may be triggered included adjusting the thermostat when a person walk through the front door, turning other smart devices on or off based on preferences, automatically adjusting lighting, adjusting HVAC systems based on present occupants, etc.
  • aspects of the systems and techniques described here provide technical improvements and advantages over existing approaches.
  • certain wireless communication devices may not automatically send MIMO transmissions in response to certain PHY layer or MAC layer messages.
  • the PHY layer also known as the physical layer, can refer to Layer 1 of the Open System Interconnection (OSI) model
  • the MAC layer also known as the data link layer
  • messages initiated by protocols in higher layers maybe used to elicit MIMO transmissions from wireless communication devices.
  • network layer messages e.g., ICMP Ping, ARP Ping, or modified versions of these and other network layer processes
  • transport layer messages e.g., TCP Ping, or modified versions of this and other transport layer processes
  • the MIMO training field contains signals having a higher frequency resolution, a greater number of subcarrier frequencies, and a higher frequency bandwidth compared to Legacy training fields in the PHY frame.
  • Use of the MIMO training field for motion detection provides more accurate motion detection capabilities. For example, in some instances, motion detection can be performed with higher spatial and temporal resolution, precision, and accuracy with the use of PHY frames, each having a respective MIMO training field. Further, since the MIMO transmissions are elicited using protocols in higher layers, MIMO transmissions may be elicited from a broader range of wireless communication devices, in a more efficient manner, or both.
  • MIMO transmissions may be elicited using existing resources on the responding device, for instance, without having to install any additional hardware, software, or firmware on the responding device (e.g., reducing or eliminating a requirement for specialized motion detection hardware in some cases).
  • the systems and techniques described here may be utilized in wireless motion detection systems or other types of wireless sensing systems.
  • eliciting MIMO transmissions may be useful in a variety of wireless sensing systems that utilize channel state information (CSI) derived from wireless signals (e.g., systems that take a CSI channel response and apply digital-signal-processing, machine learning, or other types of analysis to the CSI channel response).
  • CSI channel state information
  • the technical improvements and advantages achieved in examples where the wireless sensing system is used for motion detection may also be achieved in examples where the wireless sensing system is used for other wireless sensing applications.
  • a wireless sensing system can be implemented using a wireless communication network.
  • Wireless signals received at one or more wireless communication devices in the wireless communication network may be analyzed to determine channel information for the different communication links (between respective pairs of wireless communication devices) in the network.
  • the channel information may be representative of a physical medium that applies a transfer function to wireless signals that traverse a space.
  • the channel information includes a channel response.
  • Channel responses can characterize a physical communication path, representing the combined effect of, for example, scattering, fading, and power decay within the space between the transmitter and receiver.
  • the channel information includes beamforming state information (e.g., a feedback matrix, a steering matrix, channel state information (CSI), etc.) provided by a beamforming system.
  • Beamforming is a signal processing technique often used in multi antenna (MIMO) radio systems for directional signal transmission or reception. Beamforming can be achieved by operating elements in an antenna array in such a way that signals at particular angles experience constructive interference while others experience destructive interference.
  • the channel information for each of the communication links may be analyzed by one or more motion detection algorithms (e.g., running on a hub device, a client device, or other device in the wireless communication network, or on a remote device communicably coupled to the network) to detect, for example, whether motion has occurred in the space, to determine a relative location of the detected motion, or both.
  • the channel information for each of the communication links may be analyzed to detect whether an object is present or absent, e.g., when no motion is detected in the space.
  • a motion detection system returns motion data.
  • motion data is a result that is indicative of a degree of motion in the space, the location of motion in the space, the direction of motion in the space, a time at which the motion occurred, or a combination thereof.
  • the motion data can include a motion score, which may include, or may be, one or more of the following: a scalar quantity indicative of a level of signal perturbation in the environment accessed by the wireless signals; an indication of whether there is motion; an indication of whether there is an object present; or an indication or classification of a gesture performed in the environment accessed by the wireless signals.
  • the motion detection system can be implemented using one or more motion detection algorithms.
  • Example motion detection algorithms that can be used to detect motion based on wireless signals include the techniques described in U.S. Patent No. 9,523,760 entitled “Detecting Motion Based on Repeated Wireless Transmissions,” U.S. Patent No. 9,584,974 entitled “Detecting Motion Based on Reference Signal Transmissions,” U.S. Patent No. 10,051,414 entitled “Detecting Motion Based On Decompositions Of Channel Response Variations,” U.S. Patent No. 10,048,350 entitled “Motion Detection Based on Groupings of Statistical Parameters of Wireless Signals,” U.S. Patent No.
  • U.S. Patent No. 10,506,384 entitled “Determining a Location of Motion Detected from Wireless Signals Based on Prior Probability”
  • FIG. 1 illustrates an example wireless communication system 100.
  • the wireless communication system 100 may perform one or more operations of a motion detection system.
  • the technical improvements and advantages achieved from using the wireless communication system 100 to detect motion are also applicable in examples where the wireless communication system 100 is used for another wireless sensing application.
  • the example wireless communication system 100 includes three wireless communication devices 102A, 102B, 102C.
  • the example wireless communication system 100 may include additional wireless communication devices 102 and/or other components (e.g., one or more network servers, network routers, network switches, cables, or other communication links, etc.).
  • the example wireless communication devices 102A, 102B, 102C can operate in a wireless network, for example, according to a wireless network standard or another type of wireless communication protocol.
  • the wireless network may be configured to operate as a Wireless Local Area Network (WLAN), a Personal Area Network (PAN), a metropolitan area network (MAN), or another type of wireless network.
  • WLANs include networks configured to operate according to one or more of the 802.11 family of standards developed by IEEE (e.g., Wi-Fi networks), and others.
  • PANs include networks that operate according to short-range communication standards (e.g., BLUETOOTH®, Near Field Communication (NFC), ZigBee), millimeter wave communications, and others.
  • the wireless communication devices 102A, 102B, 102C may be configured to communicate in a cellular network, for example, according to a cellular network standard.
  • cellular networks include networks configured according to 2G standards such as Global System for Mobile (GSM) and Enhanced Data rates for GSM Evolution (EDGE) or EGPRS; 3G standards such as Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Universal Mobile Telecommunications System (UMTS), and Time Division Synchronous Code Division Multiple Access (TD-SCDMA); 4G standards such as Long-Term Evolution (LTE) and LTE- Advanced (LTE-A); 5G standards, and others.
  • GSM Global System for Mobile
  • EDGE Enhanced Data rates for GSM Evolution
  • EGPRS EGPRS
  • 3G standards such as Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Universal Mobile Telecommunications System (UMTS), and Time Division Synchronous Code Division Multiple Access (TD-SCDMA)
  • 4G standards such as Long-Term
  • one or more of the wireless communication devices 102 is a Wi-Fi access point or another type of wireless access point (WAP).
  • WAP wireless access point
  • one or more of the wireless communication devices 102 is an access point of a wireless mesh network, such as, for example, a commercially-available mesh network system (e.g., GOOGLE Wi-Fi, EERO mesh, etc.).
  • one or more of the wireless communication devices 102 can be implemented as wireless access points (APs) in a mesh network, while the other wireless communication device(s) 102 are implemented as leaf devices (e.g., mobile devices, smart devices, etc.) that access the mesh network through one of the APs.
  • APs wireless access points
  • leaf devices e.g., mobile devices, smart devices, etc.
  • one or more of the wireless communication devices 102 is a mobile device (e.g., a smartphone, a smart watch, a tablet, a laptop computer, etc.), a wireless-enabled device (e.g., a smart thermostat, a Wi-Fi enabled camera, a smart TV), or another type of device that communicates in a wireless network.
  • a mobile device e.g., a smartphone, a smart watch, a tablet, a laptop computer, etc.
  • a wireless-enabled device e.g., a smart thermostat, a Wi-Fi enabled camera, a smart TV
  • another type of device that communicates in a wireless network.
  • the wireless communication devices transmit wireless signals to each other over wireless communication links (e.g., according to a wireless network standard or a non-standard wireless communication protocol), and the wireless signals communicated between the devices can be used as motion probes to detect motion of objects in the signal paths between the devices.
  • standard signals e.g., channel sounding signals, beacon signals
  • non-standard reference signals e.g., beacon signals
  • other types of wireless signals can be used as motion probes.
  • the wireless communication link between the wireless communication devices 102A, 102C can be used to probe a first motion detection zone 110A
  • the wireless communication link between the wireless communication devices 102B, 102C can be used to probe a second motion detection zone HOB
  • the wireless communication link between the wireless communication device 102A, 102B can be used to probe a third motion detection zone HOC.
  • the motion detection zones 110 can include, for example, air, solid materials, liquids, or another medium through which wireless electromagnetic signals may propagate.
  • the motion detection system may detect the motion based on signals transmitted through the relevant motion detection zone 110.
  • the object can be any type of static or moveable object, and can be living or inanimate.
  • the object can be a human (e.g., the person 106 shown in FIG. 1), an animal, an inorganic object, or another device, apparatus, or assembly, an object that defines all or part of the boundary of a space (e.g., a wall, door, window, etc.), or another type of object.
  • the wireless signals may propagate through a structure (e.g., a wall) before or after interacting with a moving object, which may allow the object’s motion to be detected without an optical line-of-sight between the moving object and the transmission or receiving hardware.
  • the motion detection system may communicate the motion detection event to another device or system, such as a security system or a control center.
  • the wireless communication devices 102 themselves are configured to perform one or more operations of the motion detection system, for example, by executing computer-readable instructions (e.g., software or firmware) on the wireless communication devices. For example, each device may process received wireless signals to detect motion based on changes in the communication channel.
  • another device e.g., a remote server, a cloud-based computer system, a network-attached device, etc.
  • each wireless communication device 102 may send channel information to a specified device, system or service that performs operations of the motion detection system.
  • wireless communication devices 102A, 102B may broadcast wireless signals or address wireless signals to the other wireless communication device 102C, and the wireless communication device 102C (and potentially other devices) receives the wireless signals transmitted by the wireless communication devices 102A, 102B.
  • the wireless communication device 102C (or another system or device) then processes the received wireless signals to detect motion of an object in a space accessed by the wireless signals (e.g., in the zones 110A, HOB).
  • the wireless communication device 102C (or another system or device) may perform one or more operations of a motion detection system.
  • FIGS. 2A and 2B are diagrams showing example wireless signals communicated between wireless communication devices 204A, 204B, 204C.
  • the wireless communication devices 204A, 204B, 204C may be, for example, the wireless communication devices 102A, 102B, 102C shown in FIG. 1, or may be other types of wireless communication devices.
  • a combination of one or more of the wireless communication devices 204A, 204B, 204C can be part of, or may be used by, a motion detection system.
  • the example wireless communication devices 204A, 204B, 204C can transmit wireless signals through a space 200.
  • the example space 200 may be completely or partially enclosed or open at one or more boundaries of the space 200.
  • the space 200 may be or may include an interior of a room, multiple rooms, a building, an indoor area, outdoor area, or the like.
  • a first wall 202A, a second wall 202B, and a third wall 202C at least partially enclose the space 200 in the example shown.
  • the first wireless communication device 204A transmits wireless motion probe signals repeatedly (e.g., periodically, intermittently, at scheduled, unscheduled or random intervals, etc.).
  • the second and third wireless communication devices 204B, 204C receive signals based on the motion probe signals transmitted by the wireless communication device 204A.
  • an object is in a first position 214A at an initial time (tO) in FIG. 2A, and the object has moved to a second position 214B at subsequent time (t1) in FIG. 2B.
  • the moving object in the space 200 is represented as a human, but the moving object can be another type of object.
  • the moving object can be an animal, an inorganic object (e.g., a system, device, apparatus, or assembly), an object that defines all or part of the boundary of the space 200 (e.g., a wall, door, window, etc.), or another type of object.
  • an inorganic object e.g., a system, device, apparatus, or assembly
  • an object that defines all or part of the boundary of the space 200 e.g., a wall, door, window, etc.
  • another type of object e.g., a wall, door, window, etc.
  • the wireless communication devices 204A, 204B, 204C are stationary and are, consequently, at the same position at the initial time tO and at the subsequent time t1.
  • one or more of the wireless communication devices 204A, 204B, 204C may be mobile and may move between initial time tO and subsequent time t1.
  • FIGS. 2A and 2B multiple example paths of the wireless signals transmitted from the first wireless communication device 204A are illustrated by dashed lines.
  • first signal path 216 the wireless signal is transmitted from the first wireless communication device 204A and reflected off the first wall 202A toward the second wireless communication device 204B.
  • second signal path 2108 the wireless signal is transmitted from the first wireless communication device 204A and reflected off the second wall 202B and the first wall 202A toward the third wireless communication device 204C.
  • the wireless signal is transmitted from the first wireless communication device 204A and reflected off the second wall 202B toward the third wireless communication device 204C.
  • fourth signal path 222 the wireless signal is transmitted from the first wireless communication device 204A and reflected off the third wall 202C toward the second wireless communication device 204B.
  • the wireless signal is transmitted from the first wireless communication device 204A and reflected off the object at the first position 214A toward the third wireless communication device 204C.
  • the object moves from the first position 214A to a second position 214B in the space 200 (e.g., some distance away from the first position 214A).
  • the wireless signal is transmitted from the first wireless communication device 204A and reflected off the object at the second position 214B toward the third wireless communication device 204C.
  • a signal path can be added, removed, or otherwise modified due to movement of an object in a space.
  • the example wireless signals shown in FIGS. 2A and 2B may experience attenuation, frequency shifts, phase shifts, or other effects through their respective paths and may have portions that propagate in another direction, for example, through the walls 202A, 202B, and 202C.
  • the wireless signals are radio frequency (RF) signals.
  • the wireless signals may include other types of signals.
  • the transmitted signal may have a number of frequency components in a frequency bandwidth, and the transmitted signal may include one or more bands within the frequency bandwidth.
  • the transmitted signal may be transmitted from the first wireless communication device 204A in an omnidirectional manner, in a directional manner or otherwise.
  • the wireless signals traverse multiple respective paths in the space 200, and the signal along each path may become attenuated due to path losses, scattering, reflection, or the like and may have a phase or frequency offset.
  • the signals from various paths 216, 218, 220, 222, 224A, and 224B combine at the third wireless communication device 204C and the second wireless communication device 204B to form received signals.
  • the space 200 may be represented as a transfer function (e.g., a filter) in which the transmitted signal is input and the received signal is output.
  • the output of that transfer function can also change.
  • a change in the received signal can be used to detect motion of an object.
  • the output of the transfer function - the received signal - may not change.
  • FIG. 2C is a diagram showing an example wireless sensing system operating to detect motion in a space 201.
  • the example space 201 shown in FIG. 2C is a home that includes multiple distinct spatial regions or zones.
  • the wireless motion detection system uses a multi-AP home network topology (e.g., mesh network or a Self-Organizing-Network (SON)), which includes three access points (APs): a central access point 226 and two extension access points 228A, 228B.
  • APs access points
  • each AP typically supports multiple bands (2.4G, 5G, 6G), and multiple bands may be enabled at the same time.
  • Each AP may use a different Wi-Fi channel to serve its clients, as this may allow for better spectrum efficiency.
  • the wireless communication network includes a central access point 226.
  • one AP may be denoted as the central AP.
  • This selection which is often managed by manufacturer software running on each AP, is typically the AP that has a wired Internet connection 236.
  • the other APs 228A, 228B connect to the central AP 226 wirelessly, through respective wireless backhaul connections 230A, 230B.
  • the central AP 226 may select a wireless channel different from the extension APs to serve its connected clients.
  • the extension APs 228A, 228B extend the range of the central AP 226, by allowing devices to connect to a potentially closer AP or different channel.
  • the end user need not be aware of which AP the device has connected to, as all services and connectivity would generally be identical.
  • the extension APs 228A, 228B connect to the central AP 226 using the wireless backhaul connections 230A, 230B to move network traffic between other APs and provide a gateway to the Internet.
  • Each extension AP 228A, 228B may select a different channel to serve its connected clients.
  • client devices e.g., Wi-Fi client devices
  • 232A, 232B, 232C, 232D, 232E, 232F, 232G are associated with either the central AP 226 or one of the extension APs 228 using a respective wireless link 234A, 234B, 234C, 234D, 234E, 234F, 234G.
  • the client devices 232 that connect to the multi -AP network may operate as leaf nodes in the multi -AP network.
  • the client devices 232 may include wireless-enabled devices (e.g., mobile devices, a smartphone, a smart watch, a tablet, a laptop computer, a smart thermostat, a wireless-enabled camera, a smart TV, a wireless-enabled speaker, a wireless-enabled power socket, etc.).
  • wireless-enabled devices e.g., mobile devices, a smartphone, a smart watch, a tablet, a laptop computer, a smart thermostat, a wireless-enabled camera, a smart TV, a wireless-enabled speaker, a wireless-enabled power socket, etc.
  • the client devices 232 may go through an authentication and association phase with their respective APs 226, 228.
  • the association phase assigns address information (e.g., an association ID or another type of unique identifier) to each of the client devices 232.
  • address information e.g., an association ID or another type of unique identifier
  • each of the client devices 232 may identify itself using a unique address (e.g., a 48-bit address, an example being the MAC address), although the client devices 232 may be identified using other types of identifiers embedded within one or more fields of a message.
  • the address information (e.g., MAC address or another type of unique identifier) can be either hardcoded and fixed, or randomly generated according to the network address rules at the start of the association process.
  • client devices 232 Once the client devices 232 have associated to their respective APs 226, 228, their respective address information may remain fixed. Subsequently, a transmission by the APs 226, 228 or the client devices 232 typically includes the address information (e.g., MAC address) of the transmitting wireless device and the address information (e.g., MAC address) of the receiving device.
  • the wireless backhaul connections 230A, 230B carry data between the APs and may also be used for motion detection.
  • Each of the wireless backhaul channels (or frequency bands) may be different than the channels (or frequency bands) used for serving the connected Wi-Fi devices.
  • wireless links 234A, 234B, 234C, 234D, 234E, 234F, 234G may include a frequency channel used by the client devices 232A, 232B, 232C, 232D, 232E, 232F, 232G to communicate with their respective APs 226, 228.
  • Each AP may select its own channel independently to serve their respective client devices, and the wireless links 234 may be used for data communications as well as motion detection.
  • the motion detection system which may include one or more motion detection or localization processes running on the one or more of the client devices 232 or on one or more of the APs 226, 228, may collect and process data (e.g., channel information) corresponding to local links that are participating in the operation of the wireless sensing system.
  • the motion detection system may be installed as a software or firmware application on the client devices 232 or on the APs 226, 228, or may be part of the operating systems of the client devices 232 or the APs 226, 228.
  • the APs 226, 228 do not contain motion detection software and are not otherwise configured to perform motion detection in the space 201. Instead, in such implementations, the operations of the motion detection system are executed on one or more of the client devices 232.
  • the channel information may be obtained by the client devices 232 by receiving wireless signals from the APs 226, 228 (or possibly from other client devices 232) and processing the wireless signal to obtain the channel information.
  • the motion detection system running on the client devices 232 may have access to channel information provided by the client device’s radio firmware (e.g., Wi-Fi radio firmware) so that channel information may be collected and processed.
  • radio firmware e.g., Wi-Fi radio firmware
  • the client devices 232 send a request to their corresponding AP 226, 228 to transmit wireless signals that can be used by the client device as motion probes to detect motion of objects in the space 201.
  • the request sent to the corresponding AP 226, 228 may be a null data packet frame, a beamforming request, a ping, standard data traffic, or a combination thereof.
  • the client devices 232 are stationary while performing motion detection in the space 201. In other examples, one or more of the client devices 232 may be mobile and may move within the space 201 while performing motion detection.
  • a signal /(t) transmitted from a wireless communication device e.g., the wireless communication device 204A in FIGS. 2A and 2B or the APs 226, 228 in FIGS. 2C
  • ⁇ n represents the frequency of n th frequency component of the transmitted signal
  • c n represents the complex coefficient of the n th frequency component
  • t represents time.
  • an output signal r k (t) from a path k maybe described according to Equation (2): (2) where a n k represents an attenuation factor (or channel response; e.g., due to scattering, reflection, and path losses) for the n th frequency component along path k, and represents the phase of the signal for n th frequency component along path k.
  • the received signal R at a wireless communication device can be described as the summation of all output signals r k (t) from all paths to the wireless communication device, which is shown in Equation (3): (3)
  • Equation (3) Substituting Equation (2) into Equation (3) renders the following Equation (4): (4)
  • the received signal R at a wireless communication device e.g., the wireless communication devices 204B, 204C in FIGS. 2A and 2B or the client devices 232 in FIGS.
  • the received signal R at a wireless communication device can be transformed to the frequency domain, for example, using a Fast Fourier Transform (FFT) or another type of algorithm.
  • FFT Fast Fourier Transform
  • the transformed signal can represent the received signal R as a series of n complex values, one for each of the respective frequency components (at the n frequencies ⁇ n ).
  • a complex value Y n may be represented as follows in Equation (5): (5)
  • the complex value Y n for a given frequency component ⁇ n indicates a relative magnitude and phase offset of the received signal at that frequency component ⁇ n .
  • the signal /(t) may be repeatedly transmitted within a time period, and the complex value Y n can be obtained for each transmitted signal /(t).
  • the complex value Y n changes over the time period due to the channel response a n k of the space changing. Accordingly, a change detected in the channel response (and thus, the complex value Y n ) can be indicative of motion of an object within the communication channel. Conversely, a stable channel response may indicate lack of motion.
  • the complex values Y n for each of multiple devices in a wireless network can be processed to detect whether motion has occurred in a space traversed by the transmitted signals /(t).
  • the channel response can be expressed in either the time-domain or frequency-domain, and the Fourier-Transform or Inverse-Fourier-Transform can be used to switch between the time-domain expression of the channel response and the frequency-domain expression of the channel response.
  • beamforming state information may be used to detect whether motion has occurred in a space traversed by the transmitted signals /(t). For example, beamforming may be performed between devices based on some knowledge of the communication channel (e.g., through feedback properties generated by a receiver), which can be used to generate one or more steering properties (e.g., a steering matrix) that are applied by a transmitter device to shape the transmitted beam/signal in a particular direction or directions.
  • steering properties e.g., a steering matrix
  • changes to the steering or feedback properties used in the beamforming process indicate changes, which may be caused by moving objects in the space accessed by the wireless signals.
  • motion may be detected by identifying substantial changes in the communication channel, e.g. as indicated by a channel response, or steering or feedback properties, or any combination thereof, over a period of time.
  • a steering matrix may be generated at a transmitter device (beamformer) based on a feedback matrix provided by a receiver device (beamformee) based on channel sounding. Because the steering and feedback matrices are related to propagation characteristics of the channel, these beamforming matrices change as objects move within the channel. Changes in the channel characteristics are accordingly reflected in these matrices, and by analyzing the matrices, motion can be detected, and different characteristics of the detected motion can be determined.
  • a spatial map may be generated based on one or more beamforming matrices. The spatial map may indicate a general direction of an object in a space relative to a wireless communication device. In some cases, "modes” of a beamforming matrix (e.g., a feedback matrix or steering matrix) can be used to generate the spatial map. The spatial map may be used to detect the presence of motion in the space or to detect a location of the detected motion.
  • the output of the motion detection system may be provided as a notification for graphical display on a user interface on a user device.
  • the user device is the device used to detect motion, a user device of a caregiver or emergency contact designated to an individual in the space 200, 201, or any other user device that is communicatively coupled to the motion detection system to receive notifications from the motion detection system.
  • the graphical display includes a plot of motion data indicating a degree of motion detected by the motion detection system for each time point in a series of time points.
  • the graphical display can display the relative degree of motion detected by each node of the motion detection system.
  • the graphical display can help the user determine an appropriate action to take in response to the motion detection event, correlate the motion detection event with the user’s observation or knowledge, determine whether the motion detection event was true or false, etc.
  • the output of the motion detection system may be provided in real-time (e.g., to an end user). Additionally or alternatively, the output of the motion detection system may be stored (e.g., locally on the wireless communication devices 204, client devices 232, the APs 226, 228, or on a cloud-based storage service) and analyzed to reveal statistical information over a time frame (e.g., hours, days, or months). An example where the output of the motion detection system may be stored and analyzed to reveal statistical information over a time frame is in health monitoring, vital sign monitoring, sleep monitoring, etc.
  • an alert e.g., a notification, an audio alert, or a video alert
  • a motion detection event may be communicated to another device or system (e.g., a security system or a control center), a designated caregiver, or a designated emergency contact based on the output of the motion detection system.
  • a wireless motion detection system can detect motion by analyzing components of wireless signals that are specified by a wireless communication standard.
  • a motion detection system may analyze standard headers of wireless signals exchanged in a wireless communication network.
  • IEEE 802.11ax which is also known as "Wi-Fi 6.”
  • a draft of the IEEE 802.11ax standard is published in a document entitled "P802.11ax/D4.0, IEEE Draft Standard for Information Technology — Telecommunications and Information Exchange Between Systems Local and Metropolitan Area Networks — Specific Requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment Enhancements for High Efficiency WLAN,” March 2019, which is accessible at https://ieeexplore.ieee.org/document/8672643 and hereby incorporated by reference in its entirety.
  • Standard headers specified by other types of wireless communication standards may be used for motion detection in some cases.
  • a motion detection algorithm used by a wireless motion detection system utilizes a channel response (an output of a channel estimation process) computed by a wireless receiver (e.g., a Wi-Fi receiver).
  • a wireless receiver e.g., a Wi-Fi receiver
  • the channel responses computed by a channel estimation process according to a Wi-Fi 6 standard may be received as inputs to the motion detection algorithm.
  • the channel estimation in the Wi Fi 6 standard occurs at the PHY layer, using the PHY Frame (the PHY Frame is also called a PPDU) of the received wireless signal.
  • a motion detection algorithm employed by a wireless motion detection system uses channel responses computed from orthogonal frequency-division multiplexing (OFDM)-based PHY frames (including those produced by the Wi-Fi 6 standard).
  • the OFDM-based PHY frames can, in some instances, be frequency-domain signals having multiple fields, each having a corresponding frequency-domain signal.
  • OFDM-based PHY frames there are typically two types of PPDU fields that allow the Wi-Fi receiver to estimate the channel. The first is the Legacy-Training-Field, and the second are the MIMO-Training-Fields. Either or both fields may be used for motion detection.
  • An example of a MIMO-Training-Field that may be used is the so-called "High- Efficiency Long Training Field” known as HE-PHY (e.g., in the Wi-Fi 6 standard, according to the IEEE 802.11ax standard).
  • FIG. 3 shows an example PHY Frame 300 that includes an HE-LTF.
  • the example PHY Frame 300 shown in FIG. 3 is from the IEEE 802.11ax standard. These and other types of PHY frames that include an HE-LTF may be used for motion detection in some cases.
  • the example PHY Frame 300 includes a number of fields that are defined in the 802.11 standard: L-STF (Legacy Short Training Field), L-LTF (Legacy Long Training Field), L-SIG (Legacy Signal), RL-SIG (Repeated Legacy Signal), HE-SIG-A (High-Efficiency Signal), HE-STF (High-Efficiency Short Training Field), multiple HE-LTFs, Data, PE (Packet Extension).
  • the L-LTF field can be used to estimate channel responses that can be provided as input to a motion detection algorithm.
  • the HE-LTF fields which are provided as MIMO Training Fields, can also be used to estimate channel responses that can be provided as input to a motion detection algorithm.
  • the HE-LTFs can have variable duration and bandwidths, and in some examples the PHY Frame 300 breaks a 20 MHz channel into 256 frequency points (instead of 64 used by previous PHY Frame versions). As such, the example HE-LTFs in the PHY Frame 300 may provide four times better frequency resolution (e.g., compared to earlier PHY frame versions), as each point represents a frequency bandwidth of 78.125 kHz instead of 312.5 kHz. Also, the HE-LTF provides more continuous subcarriers than other fields, and hence a wider continuous bandwidth can be used for motion detection.
  • Table I shows the continuous bandwidths and frequency resolution for the HE-LTF field (labeled "HE” in the table) compared to Legacy PHY fields (L-STF and L-LTF) and other MIMO Training Fields (e.g., High- Throughput (HT) Long Training Field and Very-High-Throughput (VHT) Long Training Field).
  • HE High- Throughput
  • VHT Very-High-Throughput
  • the PHY layer is broken into 2 sub-layers: the PLCP Sublayer (Physical Layer Convergence Procedure), and the PMD Sublayer (PHY Medium Dependant).
  • the PLCP Sublayer Physical Layer Convergence Procedure
  • the format of the PHY frame is also referred to as a PPDU (PLCP Protocol Data Unit).
  • a PPDU may include fields that are used for channel estimation.
  • the PMD Sublayer (PHY Medium Dependant) provides a modulation scheme for the PHY layer.
  • IEEE 802.11 based PHY frame formats There are many different IEEE 802.11 based PHY frame formats defined.
  • a wireless motion detection system uses information derived from OFDM based PHY frames, such as, for example, those described in the following standard documents: IEEE 802.11a-1999: Legacy OFDM PHY; IEEE 802.11n-2009: HT PHY (High-Throughput); IEEE 802.11ac-2013: VHT PHY (Very- High-Throughput); IEEE 802.11ax (Draft 4.0, March 2019): HE PHY (High-Efficiency).
  • each PHY layer specification may provide its own PPDU format.
  • the example PHY frame 300 shown in FIG. 3 is an HE PHY frame provided by an ODFM PHY layer of an example 802.11 standard.
  • the OFDM PHY divides a 20 MHz channel into 64 frequency bins.
  • Modulation and Demodulation is done using 64- point complex inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT).
  • IFFT inverse Fast Fourier Transform
  • FFT Fast Fourier Transform
  • data bits grouped e.g., depending on QAM constellation
  • each group of bits is assigned to one of the subcarriers (or frequency bins); depending on QAM constellation, group of bits mapped to a complex number for each subcarrier; and a 64-point IFFT is performed to generate complex-time-domain I and Q waveforms for transmission.
  • demodulation process complex I and Q time domain signals are received; a 64-point FFT is performed to compute complex number for each subcarrier; depending on QAM constellation, each subcarrier complex number is mapped to bits; and bits from each subcarrier are re-assembled into data.
  • 64-point FFT is performed to compute complex number for each subcarrier; depending on QAM constellation, each subcarrier complex number is mapped to bits; and bits from each subcarrier are re-assembled into data.
  • not all 64 subcarriers are used; for example, only 52 of the subcarriers may be considered valid for data and pilot, and the rest of the subcarriers may be considered NULLED.
  • the PHY layer specifications in more recently-developed IEEE 802.11 standards utilize larger channel bandwidths (e.g., 40 MHz, 80 MHz, and 160 MHz).
  • FIG. 4 shows an example PHY Frame 400 that includes a Very High Throughput Long Training Field (also referred to as "VHT-LTF”).
  • the example PHY Frame 400 shown in FIG. 4 is from the IEEE 802.11ac standard.
  • a draft of the IEEE 802.11ac standard is published in a document entitled "802.11ac-2013 - IEEE Standard for Information technology-Telecommunications and information exchange between systems — Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications-Amendment 4: Enhancements for Very High Throughput for Operation in Bands below 6 GHz,” Dec. 2018, which is accessible at https://ieeexplore.ieee.org/document/7797535 and hereby incorporated by reference in its entirety.
  • These and other types of PHY frames that include a VHT-LTF may be used for motion detection in some cases.
  • the example PHY Frame 400 includes a number of components that are defined in the 802.11 standard: L-STF, L-LTF, L-SIG, VHT-SIG-A (Very- High-Throughput Signal A), VHT-STF (Veiy-High-Throughput Short Training Field), VHT- LTF (Veiy-High-Throughput Long Training Field), VHT-SIG-B (Very-High-Throughput Signal B), Data.
  • the PPDU for Legacy, HT, VHT, and HE PHYs begin with a Legacy Preamble which includes the L-STF and the L-LTF, as shown in the example PHY frame 400 in FIG. 4.
  • the L-LTF can be used for channel estimation in some cases.
  • the VHT-LTF which has a wider bandwidth compared to the L-LTF and contains similar information, can be used for MIMO channel estimation.
  • the HT-LTF and VHT-LTF are very similar, except that the VHT- LTF allows higher order MIMO and allows 80 MHz and 160 MHz channels. These fields are beneficial to use for motion detection because they can provide wider continuous bandwidth and MIMO channel information.
  • MIMO channel estimation there are generally Nr x Nc channel responses computed. This provides more information with benefit to motion detection.
  • FIG. 5 shows an example MIMO device configuration 500 including a transmitter having Nr antennas and a receiver having Nc antennas.
  • Nr x Nc channel responses may be computed based on the HE-LTF or the VHT-LTF or another MIMO training component of a PHY frame.
  • a wireless communication device computes a channel response, for example, by performing a channel estimation process based on a PHY frame. For instance, a wireless communication device may perform channel estimation based on the example PHY frame 300 shown in FIG. 3, the example PHY frame 400 shown in FIG. 4, or another type of PHY frame from a wireless signal.
  • the channel information used for motion detection may include a channel response generated by channel estimation based on the L-LTF in the PHY frame.
  • the L-LTF in the 802-llax standard can be equivalent to the LTF in the IEEE 802.11a - 1999 standard.
  • the L-LTF may be provided in the frequency domain as an input to a 64-point IFFT. Typically, only 52 of the 64 points are considered valid points for channel estimation; and the remaining points (points [-32, -26) and (26, 31]) are zero.
  • the L-LTF may be a long OFDM training symbol including 53 subcarriers (including a zero value at DC), which are modulated by the elements of a sequence L given by the following:
  • L- 26,26 ⁇ 1, 1,-I -1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1,-l 1, -1, 1, 1, 1, 1, 1, 0,
  • the example "L" vector shown above represents the complex frequency-domain representation of the field at baseband (centered around DC) and is described in page 13 of a draft of the IEEE 802.11a - 1999 standard.
  • the draft of the IEEE 802.11a - 1999 standard is published in a document entitled "802.11a- 1999 - IEEE Standard for Telecommunications and Information Exchange Between Systems - LAN/MAN Specific Requirements - Part 11: Wireless Medium Access Control (MAC) and physical layer (PHY) specifications: High Speed Physical Layer in the 5 GHz band” and accessible at https://ieeexplore.ieee.org/document/815305.
  • the example "L” vector is considered “Legacy”, as it was part of the original OFDM PHY specification, and is considered part of the legacy preamble. Hence in later specification versions, it is referred to as the L-LTF (for Legacy-Long Training Field).
  • the channel information used for motion detection may include a channel response generated by channel estimation based on one or more of the MIMO training fields in the PHY frame (e.g., the HE-LTF, HT-LTF, or VHT-LTF fields).
  • the HE-LTF may be provided in the frequency domain as an input to a 256-point IFFT. With a typical HE-LTF, there are 241 valid points (e.g., instead of 52 as in the legacy case). Each point in the HE-LTF represents a frequency range of 78.125 kHz, whereas each Legacy point represents a larger frequency range of 312.5 kHz.
  • the HE-LTF may provide higher frequency resolution, more frequency domain data points, and a larger frequency bandwidth, which can provide more accurate and higher-resolution (e.g., higher temporal and spatial resolution) motion detection.
  • An example HE-LTF is described on page 561 of the draft of the IEEE 802.11ax standard as follows:
  • Equation (27-42) the 4x HE-LTF sequence transmitted on subcamers [-122: 122] is given by Equation (27-42).
  • the 64-Point FFT Bin 600 in the top portion of FIG. 6 shows the resulting spectrum that can be measured (20 MHz and 40 MHz channels) from the L-LTF in an example PHY frame.
  • the 128-Point FFT Bin 650 in the bottom portion of FIG. 6 shows the resulting spectrum that can be measured for the same 20 MHz channels from the HE-LTF in an example PHY frame.
  • the HE-LTF may provide higher frequency resolution (more points in the same frequency bandwidth), a higher number of frequency domain data points (more bins), and a larger frequency bandwidth.
  • messages initiated by protocols in higher layers may be used to elicit MIMO transmissions from wireless communication devices.
  • the MIMO wireless signal can be used for motion detection or another type of wireless sensing application.
  • the MIMO wireless signal includes a MIMO training field that can be used for motion detection.
  • the HT-LTF, VHT-LTF or HE-LTF field in a PHY frame of a wireless transmission according to an IEEE Wi-Fi standard may be used for motion detection.
  • Such wireless signals may be transmitted through a space over a time period, for example, from one wireless communication device to another.
  • a MIMO training field (e.g., the HT-LTF, VHT-LTF or HE-LTF field) may be identified in the PHY frame of each wireless signal, and channel information may be generated based on the respective MIMO training fields. The channel information may then be used for wireless sensing (e.g., to detect motion of an object, to detect breathing, to detect gestures, etc.) of the space during the time period.
  • wireless sensing e.g., to detect motion of an object, to detect breathing, to detect gestures, etc.
  • FIG. 7 is a diagram showing a typical representation of the Open System Interconnection (OSI) model 700.
  • OSI Open System Interconnection
  • the typical OSI networking model defines seven layers: (Layer 1) the physical layer, (Layer 2) the data link layer, (Layer 3) the network layer, (Layer 4) the transport layer, (Layer 5) the session layer, (Layer 6) the presentation layer, (Layer 7) the application layer.
  • a networking model may define additional or different layers in some cases.
  • each of the OSI layers provides specified functionality and defines specified data objects.
  • a user application e.g., operating in Layer 6 and/or Layer 7 operating on a device can communicate using the standard network features represented in the OSI model 700; the user application may initiate such communication by interacting with the operating system (OS) socket library in the session layer.
  • OS operating system
  • the OS socket library exists in Layer 5, and due to standardization has virtually the same API on all modern operating systems (e.g., Linux, Windows, Android, OSX, etc).
  • Each session may be identified by a "socket handle” that is returned to the user application by the operating system, and the user application may use the socket handle when interacting with the Socket API.
  • the transport layer (Layer 4) defines a way for multiple applications to talk to each other.
  • transport layer protocols There are many transport layer protocols used; the most common are: TCP (Transmission Control Protocol), and UDP (User Datagram Protocol).
  • Applications can select, via the socket API, which protocol to use for communication.
  • Transport layer messages and the corresponding contents are identified by a "port number,” which is typically is a 16-bit value.
  • Many standardized applications have dedicated port numbers; for example, a web server typically communicates on port 80, and the OS Socket Library knows to pass data received on port 80 to the socket handle belonging to the web server.
  • the network layer provides Internet Protocol (IP) resources, which primarily allow grouping of multiple devices into a logical network.
  • IP Internet Protocol
  • Network layer services generally allow for identification of both logical network and physical device, as well as providing mechanisms for different networks to communicate with each other (typically referred to as routing).
  • the network layer may include Internet Protocol version 4 (IPv4), Internet Protocol version 6 (IPv6) or another IP version.
  • IP Internet Protocol
  • IP may serve as the communications protocol for relaying data between devices and across network boundaries (e.g., over the Internet).
  • each device is identified by a logical 32-bit address (e.g., in IPv4), or a 128- bit address (e.g., IPv6) in the network layer. Both an IPv4 and IPv6 address contain a network portion, and a device portion, which is determined based on standardized criteria.
  • IPv4 and IPv6 address contain a network portion, and a device portion, which is determined based on standardized criteria.
  • the network layer (Layer 3) is the data link layer (Layer 2) and the physical layer (Layer 1).
  • the data link layer also known as the MAC layer
  • handles coordinating how multiple devices communicate using a shared media e.g., a shared wireless channel for Wi-Fi, or another form of shared media.
  • a shared media e.g., a shared wireless channel for Wi-Fi, or another form of shared media.
  • each device is identified by a 48-bit MAC address.
  • the network layer and the data link layer are defined by the IEEE 802.11 standards.
  • the physical layer generates PHY frames for communication between devices.
  • a motion detection algorithm employed by a wireless motion detection system uses channel responses computed from orthogonal frequency-division multiplexing (OFDM)-based PHY frames (including those defined by IEEE 802.11 standards for Wi-Fi networks).
  • OFDM orthogonal frequency-division multiplexing
  • Wi-Fi signals contain multiple fields that can be used to compute a channel estimation or response.
  • MIMO LTF MIMO LTF’s
  • the MIMO fields are typically present for longer transmissions, and they consume airtime and can decrease the efficiency for short transmissions.
  • a client/leaf device needs to transmit a wireless message (e.g., a message addressed to an access point or another device in the Wi-Fi network).
  • a wireless message e.g., a message addressed to an access point or another device in the Wi-Fi network.
  • the IEEE 802.11 MAC layer standard contains a defined mechanism that states: if a device receives a data message, the device acknowledges that it was received correctly. This mechanism may provide a form of "sounding”/”illumination”, as it allows for a 0 payload length MAC frame (a Null Data Frame) to be sent to any Wi-Fi enabled device, knowing that it will return with an ACK message.
  • a limitation of the Null-Data/ACK mechanism is that the standard defines that the ACK must be transmitted using "legacy” mode, as switching to the MIMO mode for a short transmission is not efficient.
  • the wireless messages sent according to IEEE 802.11 standards do not provide a MIMO estimation unless the client/leaf device generates a large enough transmission to cause the radio to make use of the MIMO transmission mode.
  • a motion detection algorithm may also benefit from a MIMO estimation (e.g., relative to a Legacy estimation), as multiple antenna on both transmit and receive side introduce an element of spatial diversity, each illuminating or sensing a slightly different view or perspective of the environment due to the antenna’s physical separation.
  • a mechanism using standard components within higher layers in the OSI model may be utilized to elicit a MIMO channel estimation in some cases.
  • the systems and techniques described here provide solutions for using a higher layer in the OSI model to elicit a MIMO channel estimation, for example, using components in the MAC /PHY layer specifications to elicit a client/leaf node to generate a message containing a MIMO training field.
  • the solutions may exploit the fact that the higher layers encapsulate their messages into the payload of MAC/PHY "Data- Frames”, which can be transmitted containing the MIMO fields.
  • a MIMO training field can be obtained from that device.
  • FIG. 8 is a diagram showing example frame formats for three layers of a typical OSI model.
  • the diagram in FIG. 8 shows frame formats for TCP messages generated by a transport layer, IPv4 messages generated by a network layer, and 802.11 messages generated by a MAC layer.
  • the OSI Model works on the concept of "encapsulation” for transmission of messages, in which data provided from the layer above is “encapsulated” into the payload field of the message. For reception, the opposite occurs.
  • data provided in the Network layer is included in the payload field of the message in the MAC layer
  • the data provided in the Transport layer is included in the payload field of the message in the Network layer.
  • a wireless communication device can use one or more layers above the MAC layer (e.g., transport layer, network layer, or another layer above the data link layer) to elicit a MIMO transmission from another wireless communication device.
  • an access point (AP) in a wireless network e.g., a mesh node or another type of AP
  • FIGS. 9, 10, 11A, 11B, 11C, 12A, 12B, and 13 provide examples of systems and techniques that may be used to initiate or otherwise elicit client data transmission (e.g. MIMO transmission) for motion detection; other systems and techniques may be used in some instances.
  • software-implemented processes can utilize components (in some cases, existing components) in layers above the MAC layer to cause a client/leaf device transmit data. Such process may be used to enable motion detection functionality using the MIMO fields without the need to add or modify or add any software on the client/leaf device.
  • an address discovery process is used to obtain an address for communication with layers above the MAC layer. For example, channel estimation may be defined at the MAC/PHY layers, and the identification of a client/leaf device may be given by its MAC address (e.g., a 48-bit MAC address).
  • knowledge of the device’s upper layer logical address (e.g., IP address) maybe needed, and an address discovery process can be used to obtain the device’s upper layer logical address (e.g., IP address) from its lower layer physical address (e.g., MAC address).
  • an address discovery process can be used to obtain the device’s upper layer logical address (e.g., IP address) from its lower layer physical address (e.g., MAC address).
  • the operation of obtaining the device’s upper layer logical address (e.g., IP address) from its lower layer physical address (e.g., MAC address) requires a different (often more difficult) process than common procedures that obtain the lower layer physical address (e.g., MAC address) given an upper layer logical address (e.g., IP address).
  • FIG. 9 is a flow chart representing an example process 900 that finds an upper layer logical address (e.g., an IPv4 address or IPv6 address) from a lower layer physical address (e.g., a MAC address).
  • the process 900 may include additional or different operations, and the operations shown in FIG. 9 may be performed in the order shown or in another order. In some cases, one or more of the operations shown in FIG. 9 are implemented as processes that include multiple operations, sub-processes for other types of routines. In some cases, operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the process 900 may be performed by the example wireless communication devices 102A, 102B, 102C shown in FIG.
  • the upper layer logical address that is obtained from process 900 may be encapsulated in a payload field of a lower layer message.
  • the network address may be encapsulated in the payload field of a MAC layer message (e.g., as seen in FIG. 8).
  • the transport layer address may be encapsulated in the payload field of a network layer message (e.g., as seen in FIG. 8).
  • a wireless communication device can create a cache of address mappings.
  • the cache is stored on the wireless communication device and shows the mapping between the lower layer physical address (e.g., MAC address) and the upper layer logical address (e.g., network address).
  • the process 900 queries the cache (which may contain an IPv4 neighbor table or an IPv6 neighbor table depending on which protocol operates at the network layer) to determine the network address from the lower layer physical address (e.g., the MAC address).
  • the cache is queried to determine if it contains an IPv4 neighbor table.
  • the IPv4 neighbor table may also be referred to as the IPv4 Address Resolution Protocol (ARP) table.
  • ARP IPv4 Address Resolution Protocol
  • the process 900 determines whether the IPv4 neighbor table is stored in the cache.
  • the network address e.g., the IPv4 address
  • IP internet protocol
  • the fields for the network layer packet shown in FIG. 8 are setup and initialized at 906.
  • the cache is once again queried to determine if it contains an IPv6 neighbor table.
  • the process 900 determines whether the IPv6 neighbor table is stored in the cache.
  • the network address e.g., the IPv6 address
  • the IP variables for the IPv6 address are setup and initialized.
  • the network is scanned.
  • the process 900 iterates through the IPv4 and IPv6 link-local addresses to determine if one or more of the IPv4 and IPv6 link-local addresses elicits a response.
  • the process 900 determines whether an error has occurred. In some instances, an error occurs when the scanning performed at 914 does not elicit any response.
  • a delay for a predetermined time e.g., in a range from about 5 seconds to about 15 seconds
  • the cache is updated at 920 to reflect the mapping between the lower layer physical address (e.g., MAC address) and the IPv4 or IPv6 link-local address that provided the response. From 920, the process 900 is iterated from 902.
  • the lower layer physical address e.g., MAC address
  • ICMP Ping One example technique that can be used to elicit a MIMO transmission from a wireless communication device is commonly referred to as an "ICMP Ping”.
  • an ICMP Ping process is defined in the network layer, and off-the-shelf applications exist to generate such messages (e.g., ping, ping6, fping).
  • the ICMP Ping process may be explicitly defined to provide a response given a request, and may be used for network connectivity troubleshooting or other purposes.
  • the ICMP Ping process may be natively built into the network stack, and may provide a mechanism for causing a client/leaf device produce a data transmission in certain instances.
  • the ICMP Ping may utilize an IPv4, IPv6, or another similar network layer protocol.
  • ICMP integrated circuit
  • a device which has received a ping message may not generate a response, and hence may not elicit a wireless transmission that can produce a channel response measurement.
  • existing ICMP Ping and related processes can be modified to provide advantages for wireless motion detection systems.
  • the ICMP Ping processes shown in FIGS. 11A, 11B, and 11C are tailored for sending periodic requests, may provide a feedback mechanism to ensure received responses, and may provide better data efficiency (e.g., by eliminating padding and unnecessary data inserted by off-the-shelf applications).
  • Another type of ICMP Ping process maybe used.
  • ARP Ping Another example technique that can be used to elicit a MIMO transmission from a wireless communication device is referred to here as "ARP Ping”, which in some implementations may utilize aspects of the standardized ARP Exchange mechanism.
  • Address Resolution Protocol (ARP) is a protocol typically defined in the network layer; off- the-shelf applications for generating repeated standardized ARP Exchanges exist (e.g., arping).
  • ARP Address Resolution Protocol
  • ARP is a protocol typically defined in the network layer; off- the-shelf applications for generating repeated standardized ARP Exchanges exist (e.g., arping).
  • ARP Address Resolution Protocol
  • ARP may be required for all IP networked devices.
  • Devices may use ARP to obtain the data-link layer address of another device (which may be required for communication).
  • the standardized ARP Exchange process is typically used to find the MAC address of the device that holds a given network layer (IP) address.
  • IP network layer
  • Both sender addresses (1 and 2) are known to the requester because they are the local addresses of the device making the request.
  • the standardized ARP Exchange may be used when the target Network-Layer address (3) is known, but the target MAC-Layer address (4) is not known.
  • This exchange can create a request / response that is encapsulated into a MAC/PHY MIMO data transmission from the responding device in some instances. However, in other instances the standardized ARP Exchange does not elicit a MIMO transmission from the responding device. For example, some modern wireless communication devices may respond to the standardized ARP Exchange request using a legacy MAC/PHY data transmission, or can be cached and not actually transmitted.
  • a standardized ARP request is a broadcast layer-2 transmission (identified with the destination MAC address field set to ff:ff:ff:ff:ff:ff), which generally requires all devices belonging to the same logical network to receive the message.
  • This means all layer-2 network devices (such as switches, bridges, wireless access points) are required to transmit the ARP request to all clients and can result in flooding the entire network with the single request.
  • flooding an entire network is not desirable and may introduce negative effects (e.g., power consumption, air-efficiency, or wired network resources). These negative effects may impact the network globally, whether or not specific clients are participating in the motion detection system.
  • the ARP Ping processes described here can be implemented in a manner that is more efficient and avoids the negative effects mentioned above.
  • the ARP Ping process shown in FIG. 13 may send an ARP request with a known destination MAC address (and without a broadcast MAC) to eliminate the broadcast nature of the request.
  • the ARP request may be addressed to the device from which MIMO transmissions are sought.
  • Another type of ARP Ping process may be used.
  • TCP Ping Another example technique that can be used to elicit a MIMO transmission from a wireless communication device is referred to here as "TCP Ping”, which in some implementations may utilize aspects of the standardized TCP Handshake mechanism.
  • a TCP Ping can be used for sounding wireless communication devices to obtain wireless signals that can be used by a motion detection system.
  • the TCP Ping process can be used to elicit MIMO transmissions from client/leaf devices in a variety of contexts, including scenarios where the client/leaf device is configured to not respond to ICMP requests (e.g., devices that do not have ICMP enabled), and scenarios where ARP responses from the client/leaf device result in a Legacy Wi-Fi transmission or a cached response.
  • ICMP requests e.g., devices that do not have ICMP enabled
  • TCP Transmission Control Protocol
  • TCP generally operates as a connection-oriented protocol, meaning that data exchanges generally occur in both directions, which can be leveraged for eliciting MIMO transmissions from a device.
  • Example TCP Ping processes are shown in FIGS. 12A, 12B. Another type of TCP Ping process may be used.
  • a typical execution of the standardized TCP Handshake starts by a client "requesting” to start a connection with a host.
  • the client populates the SRC and DST port fields, and sets the SYN flag.
  • a host can do one of three actions: (1) It can accept the request, by responding with the ACK flag set; (2) It can reject the request, by responding with the RST flag set; or (3) It can do nothing and just drop the frame.
  • the response from action (1) is received if there is an application listening to the given port on the host, and the connection has been accepted.
  • the response from action (2) is typically received if either there is no application on the host listening to the given port, or potentially the port is blocked.
  • action (3) generally occurs if there is a firewall which has explicit instructions to drop any transmissions received by the specific host/port.
  • a result of either action (1) or action (2) may create the ping request/response action that can produce a MIMO transmission.
  • action (1) is less desirable response because an additional message exchange is then required by the client to properly close the connection (and hence consume more air-time and reduce efficiency).
  • the TCP Ping process shown in FIGS. 12A, 12B performs a "port-scan” that identifies a set of ports which responds with a result of action (2).
  • the "port-scan” may be executed, for example, in the same manner as the initial step in the standardized TCP Handshake, or in another manner. After a list of ideal ports have been obtained, one or more of them can be targeted for the TCP Ping process.
  • a delay may be added between requests (with no delay, requests may eventually be dropped); the scan phase of destination ports does not need to be linear (ports 1 to 65535) (e.g., a 16-bit maximum length PR sequence may be used to pick the destination ports); and the TCP Source Port may be randomized (e.g., a 16- bit maximum length PR sequence may be used for this).
  • scanning for and looping through 16 ports which respond to a SYN with an RST may be sufficient. This may be true in cases where the Source Port is randomized in a manner that is difficult to detect. It is also possible to periodically scan for a new set of 16 ports, however this may not be needed in all cases, for example, when pinging at a period of 100 ms.
  • FIG. 10 is a state machine diagram representing an example process 1000 that elicits MIMO transmissions from wireless communication devices.
  • the process 1000 may include additional or different operations, and the operations shown in FIG. 10 may be performed in the order shown or in another order.
  • an ICMP Ping process is followed by a TCP Ping process, which in turn is followed by an ARP Ping process.
  • any sequence or order of Ping processes may be used.
  • one or more of the operations shown in FIG. 10 are implemented as processes that include multiple operations, sub-processes for other types of routines.
  • operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the process 1000 maybe performed by the example wireless communication devices 102A, 102B, 102C shown in FIG. 1, by the example wireless communication devices 204A, 204B, 204C shown in FIGS. 2A and 2B, by any of the example devices (e.g., client devices 232 and AP devices 226, 228) shown in FIG. 2C, or by another type of device.
  • the example wireless communication devices 102A, 102B, 102C shown in FIG. 1 by the example wireless communication devices 204A, 204B, 204C shown in FIGS. 2A and 2B, by any of the example devices (e.g., client devices 232 and AP devices 226, 228) shown in FIG. 2C, or by another type of device.
  • Implementations of the example process 1000 shown in FIG. 10 may utilize ICMP Ping processes, TCP Ping processes, IPv4 ARP Ping processes, IPv6 neighbor discovery protocol, or a combination of multiple types of ping processes.
  • the process 1000 may be modified to utilize additional or different types of ping processes.
  • the example process 1000 shown in FIG. 10 combines multiple different ping mechanisms into a single protocol that can be controlled by a state machine. In some cases, by having each mechanism provide feedback to the state machine, as represented in FIG.
  • the process 1000 may select the best ping mechanism available to produce channel information to be used for motion detection.
  • feedback within each sub process is used to help the state machine determine which mechanism is the best to use and may ensure that a reliable mechanism is selected.
  • each of the three ping mechanisms provides feedback to the motion detection system, so that the motion detection system can select one of the mechanisms based on the feedback (e.g., the mechanism that provides the best data for motion detection may be selected), and the motion detection system may select a different mechanism for each client/leaf node used by the motion detection system.
  • a network layer address of a device is determined.
  • the process 900 shown in FIG. 9 or another type of process may be used to obtain an IP address of a device.
  • the ICMP Ping process includes a Setup ICMP Ping operation at 1010, an ICMP Ping operation at 1012 and a Stop ICMP Ping operation at 1014.
  • the ICMP Ping process may include additional or different operations.
  • the ICMP Ping process elicits a MIMO transmission from the device (e.g., the device corresponding to the IP address found at 1002).
  • the ICMP Ping process does not elicit a MIMO transmission from the device, and the process 1000 proceeds to the TCP Ping process.
  • two types of feedback may be used to make this decision of whether to proceed to the TCP Ping process: (1) the response received delay, and (2) the channel state information (CSI) generation rate. Either or both of these criteria can be used to evaluate the ICMP Ping process, and optionally switch to the TCP Ping process if results are not sufficient.
  • a TCP Ping process is performed. As shown in FIG. 10, the TCP Ping process includes a Setup TCP Ping operation at 1020, a TCP Ping operation at 1022 and a Stop TCP Ping operation at 1024.
  • the TCP Ping process may include additional or different operations.
  • the TCP Ping process elicits a MIMO transmission from the device (e.g., the device corresponding to the IP address found at 1002). In some cases, the TCP Ping process does not elicit a MIMO transmission from the device, and the process 1000 proceeds to the ARP Ping process.
  • two types of feedback may be used to make this decision of whether to proceed to the ARP Ping process: (1) the response received delay, and (2) the channel state information (CSI) generation rate. Either or both of these criteria can be used to evaluate the TCP Ping process, and optionally switch to the ARP Ping process if results are not sufficient.
  • CSI channel state information
  • an ARP Ping process is performed. As shown in FIG. 10, in instances where the IP address is an IPv4 address, the ARP Ping process includes a Setup IPv4 ARP Ping operation at 1030, an IPv4 ARP Ping operation at 1032 and a Stop IPv4 ARP Ping operation at 1034. In instances where the IP address is an IPv6 address, the ARP Ping process includes a Setup IPv6 neighbor discovery protocol operation at 1030, an IPv6 neighbor discovery protocol operation at 1032 and a Stop IPv6 neighbor discovery protocol operation at 1034. The ARP Ping process may include additional or different operations.
  • the ARP Ping process elicits a MIMO transmission from the device (i.e., the device corresponding to the IP address found at 1002). In some cases, the ARP Ping process does not elicit a MIMO transmission from the device, and the process 1000 proceeds to 1040. In some implementations, two types of feedback may be used to make this decision of whether to proceed to operation 1040: (1) the response received delay, and (2) the channel state information (CSI) generation rate. Either or both of these criteria can be used to evaluate the ARP Ping process, and optionally reiterate to another mechanism if results are not sufficient. At 1040, a neighbor cache is flushed, and the process 1000 proceeds to another iteration beginning at 1002.
  • CSI channel state information
  • FIG. 11A shows a flowchart representing an example process 1100 to setup an ICMP ping.
  • FIG. 11B shows a flowchart of an example process 1110 to stop an ICMP ping.
  • FIG. llC shows a flowchart representing an example process 1120 to conduct an ICMP ping.
  • the respective processes 1100, 1110, 1120 may include additional or different operations, and the operations shown in FIGS. 11A, 11B, and 11C may be performed in the order shown or in another order. In some cases, one or more of the operations shown in FIGS. 11A, 11B, and 11C are implemented as processes that include multiple operations, sub-processes for other types of routines.
  • operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the processes 1100, 1110, 1120 may be performed by the example wireless communication devices 102A, 102B, 102C shown in FIG. 1, by the example wireless communication devices 204A, 204B, 204C shown in FIGS. 2A and 2B, by any of the example devices (e.g., client devices 232 and AP devices 226, 228) shown in FIG. 2C, or by another type of device.
  • the example processes 1100, 1110, 1120 shown in FIGS. 11A, 11B, and 11C may be used, for example, to perform operations 1010, 1014, 1012, respectively in the example process 1000 shown in FIG. 10.
  • the example processes 1100, 1110, 1120 shown in FIGS. 11A, 11B, and 11C may be used in another context.
  • the ICMP Ping processes represented in FIGS. 11A, 11B, and 11C can provide advantages, for example, as noted above.
  • the example process 1100 in FIG. 11A illustrates initialization logic for an ICMP ping process.
  • the process 1100 initializes computing resources and message fields that are needed for the ICMP ping process 1110.
  • the example process 1100 includes determining whether a timer has been set up successfully (at 1101).
  • setting up the timer includes initiating an operating system (OS) -level call requesting the OS to set up a timer handle.
  • OS operating system
  • there may not be computing resources to set up the timer handle and the OS may return an error message indicating the absence of such resources, thus indicating that the timer has not been set up successfully.
  • the OS may return a message indicating successful set up of the timer handle.
  • the ICMP Ping mechanism may be terminated (e.g., by performing the process 1110 shown in FIG. 11B).
  • a determination is made (at 1103) as to whether a socket has been opened successfully.
  • setting up the socket includes initiating an OS-level call requesting the OS to set up a socket handle.
  • the OS may return an error message indicating the absence of such resources, thus indicating that the socket has not been set up successfully.
  • the OS may return a message indicating successful set up of the socket handle.
  • the ICMP Ping mechanism may be terminated (e.g., by performing the process 1110 shown in FIG. 11B). Conversely, in response to a determination that the socket has been opened successfully, the process 1100 proceeds to initialize a raw ICMP echo request frame (e.g., at 1105). At 1105, fields that are required for the ICMP ping messages are initialized and placed in the payload of the IPv4 or IPv6 frame.
  • a sequence counter is initialized to zero.
  • the sequence counter tracks the number of ICMP ping messages that are sent, and each ICMP ping message is matched to a respective sequence number (e.g., described in the example of FIG. 11C).
  • CSI rate feedback is initialized.
  • the device from which MIMO transmissions are elicited can provide CSI to the device transmitting the ICMP ping messages.
  • the example process 1110 in FIG. 11B illustrates termination logic for an ICMP ping process.
  • the process 1110 releases the computing resources that were requested in the initialization process 1100.
  • the timer e.g., requested at 1101
  • the socket e.g., requested at 1103
  • the timer is disabled and the socket is closed by an OS-level call that indicates, to the OS, that these resources are no longer needed.
  • the example process 1120 in FIG. 11C illustrates a process of conducting the ICMP ping.
  • the ICMP ping includes sending a predetermined number of consecutive ICMP ping messages (e.g., using the operations at 1121, 1123, 1125, 1127, 1129, 1131).
  • the predetermined number of consecutive ICMP ping messages may be referred to as a block of ICMP ping messages.
  • the number of consecutive ICMP ping messages within the block (referred to as "BLOCKSIZE”) can be an application- specific tuned parameter, for example 64 ICMP ping messages.
  • the "BLOCKSIZE” can also be set based on the period at which the space 200, 201 is sampled for motion.
  • the space 200, 201 is sampled every 100 milliseconds, and a reasonable "BLOCKSIZE” is equal to 64 ICMP ping messages.
  • the process 1120 analyzes the received responses (e.g., using the operations at 1133, 1135, 1137, 1139) to determine whether MIMO transmissions have been successfully elicited by the block of ICMP ping messages or whether a further block of ICMP ping messages needs to be transmitted.
  • an ICMP ping message is updated.
  • an ICMP ping message may be referred to as an echo request frame, and updating the ICMP ping message may include updating fields (e.g., the checksum field) of the ICMP ping message.
  • a timer tick is awaited. The timer tick allows for a predetermined period of time (e.g., about 100 milliseconds) to elapse so that a wireless signal (e.g., a MIMO transmission) can be received in response to a previously transmitted ICMP ping message.
  • the predetermined period of time may be equal to the period at which the space 200, 201 is sampled for motion.
  • the timestamp of the ICMP ping message that was updated at 1121 is determined. In some instances, the timestamp of the ICMP ping message is matched to the current sequence number.
  • the ICMP ping message that was updated at 1121 is sent. In some implementations, the ICMP ping message may be referred to as an ICMP echo request.
  • the sequence counter is incremented (at 1131) and process 1120 is iterated from 1121.
  • a feedback or check mechanism is executed.
  • the feedback or check mechanism (e.g., including operations 1133, 1135, 1137, 1139) is executed after the block of ICMP ping messages has been sent.
  • the timestamps of the received responses are processed to determine a difference between the time a respective ICMP ping message was transmitted (e.g., obtained from the timestamp associated with the ICMP ping message) and the time its corresponding response was received. If the time difference associated with any ICMP ping message within the block of ICMP ping messages is greater than a threshold, then the entire block of ICMP ping messages is deemed to be a failed block. This failure logic may be implemented inside operation 1133 that processes timestamps of received responses.
  • the threshold number of failures is depicted as being 10, but another integer threshold number may be used in other examples.
  • a determination that the number of consecutive failed blocks is greater than the threshold number of failures may indicate that repeated blocks of ICMP ping messages have failed to elicit successful MIMO transmissions from a wireless communication device. Therefore, in response to a determination that the number of consecutive failed blocks is greater than the threshold number of failures, the ICMP Ping mechanism may be terminated in favor of attempting another type of mechanism.
  • a secondary feedback check is performed.
  • the secondary feedback check is referred to in FIG. 11C as CSI rate feedback (CSI Rate FB) (e.g., in operations 1137 and 1139).
  • the checks performed at 1137 and 1139 determine the rate at which MIMO transmissions (including CSI) are being received in response to the block of ICMP ping messages. If the ICMP Ping response is encapsulated by the client/leaf device in a MAC data frame that does not contain a MIMO training field, the response times may pass the check at 1135, but without a MIMO training field, there may be no CSI output from the radio. Accordingly, the secondary check at 1137 and 1139 may be used to ensure the block of ICMP ping messages elicits responses containing a MIMO training field.
  • a determination that the average CSI rate is greater than or equal to twice the period at which the space 200, 201 is sampled may indicate that MIMO transmissions (including CSI) are not being received at a rate that is fast enough to accurately or reliably detect motion in the space 200, 201.
  • the ICMP Ping mechanism may be terminated in favor of attempting another type of mechanism. Conversely, if CSI rate feedback is not enabled or if the average CSI rate is less than twice the period at which the space 200, 201, the sequence counter is incremented (at 1131) and process 1120 is iterated from 1121.
  • FIG. 12A shows a flow chart representing an example process 1200 to setup a TCP Ping.
  • FIG. 12B shows a flow chart representing an example process 1210 to conduct a TCP Ping.
  • the respective processes 1200, 1210 may include additional or different operations, and the operations shown in FIGS. 12A and 12B may be performed in the order shown or in another order.
  • one or more of the operations shown in FIGS. 12A and 12B are implemented as processes that include multiple operations, sub processes for other types of routines.
  • operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the processes 1200 and 1210 may be performed by the example wireless communication devices 102A, 102B, 102C shown in FIG.
  • the example processes 1200, 1210 shown in FIGS. 12A, 12B maybe used, for example, to perform operations 1020, 1022 in the example process 1000 shown in FIG. 10. In some implementations, the example processes 1200, 1210 shown in FIGS. 12A, 12B may be used in another context.
  • the example processes 1200 determines the number of valid TCP ports in the network, obtains a valid local interface IP address, and initializes computing resources and message fields that are needed for the TCP ping process 1210.
  • the example process 1200 includes scanning the network for TCP ports (at 1201).
  • the network is scanned for TCP ports by sending a TCP packet with a set synchronize (SYN) flag to each port identifier.
  • SYN set synchronize
  • FIG. 8 shows a TCP packet having various fields, including a field for various flags.
  • the SYN flag depicted in the example of FIG. 8 may be set in the TCP packet that is sent to each port identifier.
  • a port identifier is a 16-bit identifier
  • the TCP packet with the set SYN flag is sent to each unique 16-bit identifier.
  • a valid TCP port may respond to the TCP packet having the set SYN flag with a TCP packet having a set reset (RST) flag.
  • RST set reset
  • the RST flag depicted in the example of FIG. 8 may be set in the TCP packet that is sent as a response.
  • a determination is made as to whether there is more than one valid TCP port.
  • the number of valid TCP ports is determined by counting the number of received TCP packets having a set RST flag.
  • the TCP ping setup In response to a determination that there is less than or equal to one valid TCP port, the TCP ping setup is terminated (e.g., in favor of attempting another type of mechanism). Conversely, in response to a determination that there is more than one valid TCP port, a determination is made (at 1205) as to whether a timer has been set up successfully. In some implementations, an OS-level call similar to the OS-level call described for operation 1101 may be used to determine whether the timer has been set up successfully. [00143] In response to a determination that the timer has not been set up successfully, the TCP ping setup is terminated (e.g., in favor of attempting another type of mechanism).
  • An OS-level call similar to the OS-level call described for operation 1103 maybe used to determine whether the socket has been set up successfully.
  • a local interface IP address is requested (at 1209).
  • requesting a local interface IP address includes initiating an OS-level call requesting a local interface IP address from the OS.
  • a determination is made as to whether a valid local interface IP address has been obtained.
  • a valid local interface IP address is obtained when there are sufficient computing resources available for the OS to provide the local interface IP address. In some instances, there may not be computing resources to provide a local interface IP address, and the OS may return an error message indicating this. Therefore, a valid local interface IP address is not obtained when there are insufficient computing resources available to provide the local interface IP address.
  • the TCP ping setup In response to a determination that a valid local interface IP address is not obtained, the TCP ping setup is terminated (e.g., in favor of attempting another type of mechanism). Conversely, in response to a determination that a valid local interface IP address has been obtained, variables of a TCP ping message are set up (at 1213). For example, the various fields of the example TCP packet shown in FIG. 8 are set up at 1213. In some instances, a TCP ping message may be referred to as a datagram (indicated in FIG.
  • TCP fields and the contents of the datagram are initialized. For example, the various fields of the TCP packet shown in FIG. 8 are initialized at 1215.
  • file descriptors (indicated in FIG.
  • the select function is configured to inform the OS to generate an alert when an event included in the file descriptors has occurred.
  • the file descriptors can include the reception of a TCP packet having a set RST flag, a timer expiration, or both. Therefore, in such implementations, the OS generates an alert when the timer has expired or when a TCP packet having a set RST flag is received.
  • the timer is set to expire after a predetermined period of time, which may be equal to the period at which the space 200, 201 is sampled for motion (e.g., 100 milliseconds in some instances).
  • CSI rate feedback is initialized.
  • the device from which MIMO transmissions are elicited can provide CSI to the device transmitting the ICMP ping messages.
  • CSI rate feedback can be obtained from the MIMO transmissions that are elicited by the TCP ping messages, and the rate at which the CSI is being received can be determined to ascertain whether CSI is being received at a rate that is fast enough to accurately or reliably detect motion in the space 200, 201.
  • the example process 1210 in FIG. 12B illustrates a process of conducting the TCP ping.
  • the TCP ping includes sending a predetermined number of consecutive TCP ping messages (e.g., using the operations at 1221, 1223, 1225, 1227, 1229, 1231, 1233, 1235, 1237).
  • the predetermined number of consecutive TCP ping messages may be referred to as a block of datagrams.
  • the number of consecutive datagrams within the block (referred to as "BLOCKSIZE”) can be an application-specific tuned parameter, for example 64 datagrams.
  • the "BLOCKSIZE” can depend on the period at which the space 200, 201 is sampled for motion.
  • the space 200, 201 is sampled every 100 milliseconds, and a reasonable "BLOCKSIZE” is equal to 64 datagrams.
  • the process 1210 analyzes the received responses (e.g., using the operations at 1239, 1241, 1243, 1245) to determine whether MIMO transmissions have been successfully elicited by the block of datagrams or whether a further block of datagrams needs to be transmitted.
  • the select function is executed. The select function waits for an event included in the file descriptors to occur.
  • the file descriptors can include the reception of a TCP packet having a set RST flag, expiration of the timer, or both. In essence, at 1221, a period of time is allowed to elapse so that a wireless signal (e.g., a MIMO transmission) can be received in response to a previously transmitted TCP ping message.
  • the determination at 1223 ascertains whether the alert at 1221 can be attributed to the expiration of the timer.
  • a determination is made (at 1225) as to whether a TCP packet having a set RST flag was received.
  • the determination at 1225 ascertains whether the alert at 1221 can be attributed to the reception of a TCP packet having a set RST flag.
  • process 1210 is iterated starting at 1221.
  • the timestamp of the received datagram is obtained and the timestamp is used to indicate the time at which the datagram is received (at 1227).
  • the process 1210 is subsequently iterated starting at 1221.
  • the datagram is updated (at 1229).
  • the port identifiers e.g., 16-bit port identifiers
  • a valid source port indicated in FIG. 12B as "sport” and shown in FIG. 8 as "Source Port”
  • a valid destination port indicated in FIG. 12B as “dport” and shown in FIG. 8 as “Destination Port”
  • the port identifiers for valid source and destination ports may be obtained, as an example, at 1201 and 1203 when the network is scanned for valid TCP ports.
  • the timestamp of the datagram that was updated at 1229 is determined. In some instances, the timestamp of the datagram is matched to the current sequence number.
  • the datagram that was updated at 1229 is sent (e.g., from the valid source port to the valid destination port). In some implementations, the datagram is sent as a TCP packet having a set SYN flag.
  • a determination is made as to whether the predetermined number of consecutive datagrams (e.g., "BLOCKSIZE”) has been sent.
  • the sequence counter is incremented, a valid source port is pseudo-randomly chosen, and the next valid destination port is selected (at 1237), and process 1210 is iterated from 1221.
  • a feedback or check mechanism is executed.
  • the feedback or check mechanism (e.g., including operations 1239, 1241, 1243, 1245) is executed after the block of datagrams has been sent.
  • the timestamps of the received responses are processed to determine a difference between the time a respective datagram was transmitted (e.g., obtained from the timestamp associated with the datagram) and the time its corresponding response was received. If the time difference associated with any datagram within the block of datagrams is greater than a threshold, then the entire block of datagrams is deemed to be a failed block.
  • This failure logic may be implemented inside operation 1239 that processes timestamps of received responses.
  • the threshold number of failures is depicted as being 10, but another integer threshold number may be used in other examples.
  • a determination that the number of consecutive failed blocks is greater than the threshold number of failures may indicate that repeated blocks of datagrams (or TCP ping messages) have failed to elicit successful MIMO transmissions from a wireless communication device. Therefore, in response to a determination that the number of consecutive failed blocks is greater than the threshold number of failures, the TCP Ping mechanism may be terminated in favor of attempting another type of mechanism.
  • a secondary feedback check is performed.
  • the secondary feedback check is referred to in FIG. 12B as CSI rate feedback (CSI Rate FB) (e.g., in operations 1243 and 1245).
  • the checks performed at 1243 and 1245 determine the rate at which MIMO transmissions (including CSI) are being received in response to the block of datagrams. If the TCP packet having a set SYN flag is encapsulated by the client/leaf device in a MAC data frame that does not contain a MIMO training field, the response times may pass the check at 1241, but without a MIMO training field, there may be no CSI output from the radio. Accordingly, the secondary check at 1243 and 1245 may be used to ensure the block of datagrams elicits responses containing a MIMO training field.
  • a determination that the average CSI rate is greater than or equal to twice the period at which the space 200, 201 is sampled may indicate that MIMO transmissions (including CSI) are not being received at a rate that is fast enough to accurately or reliably detect motion in the space 200, 201. Consequently, in response to a determination that the average CSI rate is greater than or equal to twice the period at which the space 200, 201 is sampled, the TCP Ping mechanism may be terminated in favor of attempting another type of mechanism.
  • FIG. 13 shows a flow chart representing an example process 1300 to setup an ARP ping.
  • the process 1300 may include additional or different operations, and the operations shown in FIG. 13 may be performed in the order shown or in another order.
  • one or more of the operations shown in FIG. 13 are implemented as processes that include multiple operations, sub-processes for other types of routines.
  • operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the process 1400 may be performed by the example wireless communication devices 102A, 102B, 102C shown in FIG. 1, by the example wireless communication devices 204A, 204B, 204C shown in FIGS.
  • the example process 1300 shown in FIG. 13 may be used, for example, to perform operation 1030 in the example process 1000 shown in FIG. 10.
  • the example process 1300 shown in FIG. 13 may be used in another context.
  • the ARP Ping processes represented in FIG. 13 can provide advantages, for example, compared to using standard tools (e.g., arping). For instance, the ARP Ping process represented in FIG. 13 may provide an ARP request without a broadcast MAC, but instead with the desired destination MAC address (which is already known), which can eliminate the broadcast nature of the ARP request.
  • the example process 1300 is used when the IPv4 protocol operates at the network layer, and at 1301, a determination is made as to whether the IPv4 protocol is used.
  • the cache that is queried at 902 in FIG. 9 contains an IPv4 neighbor table when the IPv4 protocol is used, and thus the determination made at 1301 can be made based whether an IPv4 neighbor table exists in the cache queried at 902.
  • the ARP Ping setup may be terminated (e.g., in favor of attempting another type of mechanism).
  • an OS-level call similar to the OS-level call described for operation 1101 may be used to determine whether the timer has been set up successfully.
  • the ARP ping setup is terminated (e.g., in favor of attempting another type of mechanism). Conversely, in response to a determination that the timer has been setup successfully, a determination is made (at 1305) as to whether a socket has been opened successfully.
  • An OS-level call similar to the OS-level call described for operation 1103 maybe used to determine whether the socket has been set up successfully.
  • a local interface IP address and a MAC address are requested (at 1307).
  • requesting a local interface IP address and a MAC address includes initiating an OS-level call requesting a local interface IP address and a MAC address from the OS.
  • a valid local interface IP address is obtained when there are sufficient computing resources available for the OS to provide the local interface IP address. In some instances, there may not be computing resources to provide a local interface IP address, and the OS may return an error message indicating this. Therefore, a valid local interface IP address is not obtained when there are insufficient computing resources available to provide the local interface IP address.
  • the ARP ping setup is terminated (e.g., in favor of attempting another type of mechanism). Conversely, in response to a determination that a valid local interface IP address has been obtained, the process 1300 proceeds to initialize a raw ARP request frame (e.g., at 1311). At 1311, fields that are required for the ARP ping messages are initialized and placed in the payload of the IPv4 frame.
  • CSI rate feedback is initialized.
  • the device from which MIMO transmissions are elicited can provide CSI to the device transmitting the ARP ping messages.
  • CSI rate feedback can be obtained from the MIMO transmissions that are elicited by the ARP ping messages, and the rate at which the CSI is being received can be determined to ascertain whether CSI is being received at a rate that is fast enough to accurately or reliably detect motion in the space 200, 201.
  • FIG. 14 shows a flowchart representing an example process 1400 of eliciting MIMO transmissions from wireless communication devices.
  • the process 1400 may include additional or different operations, and the operations shown in FIG. 14 may be performed in the order shown or in another order. In some cases, one or more of the operations shown in FIG. 14 are implemented as processes that include multiple operations, sub processes for other types of routines. In some cases, operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the process 1400 may be performed by the example wireless communication devices 102A, 102B, 102C shown in FIG. 1, by the example wireless communication devices 204A, 204B, 204C shown in FIGS. 2A and 2B, by any of the example devices (e.g., client devices 232 and AP devices 226, 228) shown in FIG. 2C, or by another type of device.
  • the process 1400 may be performed by a wireless communication device that seeks to elicit MIMO transmissions from another wireless communication device.
  • network or transport layer messages are generated.
  • Network layer messages may be generated when an ICMP ping process (e.g., described in FIGS. 11A, 11B, 11C) or an ARP ping process (e.g., described in FIG. 13) is used to elicit the MIMO transmissions.
  • the network layer messages may be encapsulated into the payload field of respective Media Access Control (MAC) layer messages.
  • Transport layer messages may be generated when a TCP ping process (e.g., described in FIGS. 12A, 12B) is used to elicit the MIMO transmissions.
  • TCP ping process e.g., described in FIGS. 12A, 12B
  • transport layer messages that may be generated may be encapsulated into the payload field of respective network layer messages.
  • the network or transport layer messages may be addressed to the device from which MIMO transmissions are sought.
  • the address of the device from which MIMO transmissions are sought may be an upper layer logical address (e.g., network address) of the device and may be obtained using the process described in FIG. 10.
  • the network or transport layer messages are wirelessly transmitted to the device from which MIMO transmissions are sought.
  • the network layer messages may be wirelessly transmitted according to the ICMP Ping process (e.g., described in FIGS. 11A, 11B, 11C), the ARP Ping process (e.g., described in FIG. 13), or a combination thereof.
  • the transport layer messages may be wirelessly transmitted according to the TCP Ping process (e.g., described in FIGS. 12A, 12B).
  • the device that transmits the network or transport layer messages may detect a failure of the network or transport layer messages to elicit successful MIMO transmissions from the device to which the network or transport layer messages are addressed.
  • the failure of the network or transport layer messages to elicit successful MIMO transmissions may manifest itself as the number of consecutive failed blocks being greater than a threshold number of failures (e.g., at 1135 in FIG. llC or at 1241 in FIG. 12B) or the MIMO transmissions (including CSI) are not being received at a rate that is fast enough to accurately or reliably detect motion in the space (e.g., at 1139 in FIG. 11C or at 1245 in FIG. 12B).
  • the device that transmits the network or transport layer messages may terminate the mechanism used to transmit the network or transport layer messages in favor of attempting another type of mechanism to transmit the network or transport layer messages.
  • an ICMP ping process that transmits network layer messages may fail to elicit successful MIMO transmissions, and the device may instead transmit transport layer messages using a TCP ping process to elicit successful MIMO transmissions.
  • a TCP ping process that transmits transport layer messages may fail to elicit successful MIMO transmissions, and the device may instead transmit network layer messages using an ARP ping process to elicit successful MIMO transmissions.
  • MIMO transmissions are received from the device to which the network or transport layer messages are addressed.
  • the MIMO transmissions can include MIMO training fields.
  • the MIMO training fields contain signals (e.g., CSI) having a higher frequency resolution, a greater number of subcarrier frequencies, and a higher frequency bandwidth compared to Legacy training fields in the PHY frame.
  • Use of the MIMO training field for motion detection provides more accurate motion detection capabilities. Therefore, at 1408, a training field is identified in each MIMO transmission, and channel information is generated based on the training field (at 1410). At 1412, the channel information is used to detect motion that occurred in a space (e.g., the space 200, 201).
  • FIG. 15 is a block diagram showing an example wireless communication device 1500.
  • the example wireless communication device 1500 includes an interface 1530, a processor 1510, a memory 1520, and a power unit 1540.
  • a wireless communication device e.g., any of the wireless communication devices 102A, 102B, 102C in FIG. 1, wireless communication devices 204A, 204B, 204C shown in FIGS. 2A and 2B, client devices 232 and AP devices 226, 228 shown in FIG. 2C
  • the wireless communication device 1500 may be configured to operate as described with respect to the examples above.
  • the interface 1530, processor 1510, memory 1520, and power unit 1540 of a wireless communication device are housed together in a common housing or other assembly.
  • one or more of the components of a wireless communication device can be housed separately, for example, in a separate housing or other assembly.
  • the example interface 1530 can communicate (receive, transmit, or both) wireless signals.
  • the interface 1530 maybe configured to communicate radio frequency (RF) signals formatted according to a wireless communication standard (e.g., Wi Fi, 4G, 5G, Bluetooth, etc.).
  • RF radio frequency
  • the example interface 1530 includes a radio subsystem and a baseband subsystem.
  • the radio subsystem may include, for example, one or more antennas and radio frequency circuitry.
  • the radio subsystem can be configured to communicate radio frequency wireless signals on the wireless communication channels.
  • the radio subsystem may include a radio chip, an RF front end, and one or more antennas.
  • the baseband subsystem may include, for example, digital electronics configured to process digital baseband data.
  • the baseband subsystem may include a digital signal processor (DSP) device or another type of processor device.
  • DSP digital signal processor
  • the baseband system includes digital processing logic to operate the radio subsystem, to communicate wireless network traffic through the radio subsystem or to perform other types of processes.
  • the example processor 1510 can execute instructions, for example, to generate output data based on data inputs.
  • the instructions can include programs, codes, scripts, modules, or other types of data stored in memory 1520. Additionally or alternatively, the instructions can be encoded as pre-programmed or re-programmable logic circuits, logic gates, or other types of hardware or firmware components or modules.
  • the processor 1510 may be or include a general-purpose microprocessor, as a specialized co-processor or another type of data processing apparatus. In some cases, the processor 1510 performs high level operation of the wireless communication device 1500.
  • the processor 1510 may be configured to execute or interpret software, scripts, programs, functions, executables, or other instructions stored in the memory 1520. In some implementations, the processor 1510 be included in the interface 1530 or another component of the wireless communication device 1500.
  • the example memory 1520 may include computer-readable storage media, for example, a volatile memory device, a non-volatile memory device, or both.
  • the memory 1520 may include one or more read-only memory devices, random-access memory devices, buffer memory devices, or a combination of these and other types of memory devices.
  • one or more components of the memory can be integrated or otherwise associated with another component of the wireless communication device 1500.
  • the memory 1520 may store instructions that are executable by the processor 1510.
  • the instructions may include instructions to perform one or more of the operations described above.
  • the example power unit 1540 provides power to the other components of the wireless communication device 1500.
  • the other components may operate based on electrical power provided by the power unit 1540 through a voltage bus or other connection.
  • the power unit 1540 includes a battery or a battery system, for example, a rechargeable battery.
  • the power unit 1540 includes an adapter (e.g., an AC adapter) that receives an external power signal (from an external source) and coverts the external power signal to an internal power signal conditioned for a component of the wireless communication device 1500.
  • the power unit 1540 may include other components or operate in another manner.
  • Wireless signals may be communicated (e.g., transmitted and received) among the respective wireless communication devices shown in the example wireless communication systems of FIGS. 1, 2A, 2B, and 2C.
  • data maybe communicated on one or more wireless links of the example wireless communication systems of FIGS. 1, 2A, 2B, and 2C.
  • the data that is communicated can be unicast data, multicast data, or broadcast data, depending on the wireless communication devices the data is addressed or expected to be delivered to.
  • unicast data is addressed and intended to have a single destination or recipient.
  • AP 228A may transmit unicast data addressed to and intended for client device 232B.
  • the other client devices 232A, 232C, 232D, and 232E are not intended recipients of the unicast data from AP 228A.
  • Multicast data is addressed and intended to have one or more destinations or recipients.
  • AP 228A may transmit multicast data addressed to and intended for client devices 232A, 232B, 232C.
  • the other client devices 232D, 232E are not intended recipients of the multicast data from AP 228A.
  • Broadcast data is intended to be delivered to all devices within a broadcast footprint.
  • the broadcast footprint can be determined by the network portion of the IP address, which can be defined by an IP subnet mask.
  • the client devices 232A, 232B, 232C, 232D, 232E may be within the broadcast footprint of the AP 228A, and the AP 228A may transmit broadcast data intended for all the client devices 232A, 232B, 232C, 232D, 232E.
  • the example wireless communication systems of FIGS. 1, 2A, 2B, and 2C maybe configured to operate according to one or more of the IEEE 802.11 family of standards.
  • the example wireless communication systems may operate as a Wi-Fi network, which can have a built-in power saving feature that allows a wireless communication device (e.g., an AP device or a client device) to power off transmission and reception components for a negotiated amount of time, without any loss of data.
  • a Wi-Fi network can have a built-in power saving feature that allows a wireless communication device to enter a sleep mode for a predetermined duration (e.g., to reduce or conserve power consumption).
  • the Wi-Fi network can have a built-in power saving feature that causes the power unit 1540 shown in FIG. 15 to cause the wireless communication device 1500 to enter a sleep mode for a predetermined duration (e.g., to reduce power consumption of the wireless communication device 1500).
  • Example wireless communication devices that can use the built-in power saving feature of a Wi-Fi network include the example wireless communication devices 102A, 102B, 102C shown in FIG. 1, the example wireless communication devices 204A, 204B, 204C shown in FIGS. 2A and 2B, or the example devices (e.g., client devices 232 or AP devices 226, 228) shown in FIG. 2C, or any other wireless communication device.
  • client devices e.g., Wi-Fi client devices
  • 232A, 232B, 232C, 232D, 232E, 232F, 232G can be associated with either the central AP 226 or one of the extension APs 228 using a respective wireless link 234A, 234B, 234C, 234D, 234E, 234F, 234G.
  • FIG. 16 shows an example exchange of messages in an association process 1600 between a client device 1602 and an AP device 1604.
  • the client device 1602 can be identified with any of example client device 102A, 102B, 102C, 204A, 204B, 204C, 232 shown in FIGS. 1, 2A, 2B, and 2C, or any other client device.
  • the AP device 1604 can be identified with any example AP device shown in FIGS. 1, 2A, 2B, and 2C, or any other AP device.
  • the client device 1602 and the AP device 1604 are co-located in a space 1606, and after the association process 1600, the devices 1602, 1604 can be nodes in a Wi-Fi network.
  • the client device 1602, the AP device 1604, or both can carry out a search within their respective ranges (e.g., about 10 meters) to find other wireless communication devices that have registered themselves as being visible or discoverable to other wireless communication devices.
  • the AP device 1604 periodically transmits a beacon signal, which can be used by the client device 1602 to discover the AP device 1604.
  • Each beacon signal can be a broadcast message (e.g., for associated and non-associated client devices).
  • the rate at which the beacon signals are transmitted can be programmable by a network operator, and in some instances, a beacon signal is transmitted about every 100 ms (e.g., about every 102.4 ms).
  • Each beacon signal transmitted by the AP device 1604 can contain information about the wireless network.
  • each beacon signal can be used by the AP device 1604 to announce or broadcast the presence of the wireless network, identify the wireless network and its supported capabilities, synchronize the times on all associated client devices, and broadcast a traffic indication map (TIM) element (e.g., discussed in further detail below).
  • TIM traffic indication map
  • Each beacon signal can be used by the AP device 1604 for other purposes, in some implementations.
  • the client device 1602 can transmit an association request message 1608 to the AP device 1604.
  • the association request message 1608 includes multiple fields 1610 related to the capabilities of the client device 1602. With regards to the built-in power saving feature in a Wi-Fi network, the multiple fields 1610 of the association request message 1608 includes a Listen Interval field 1612, which the client device 1602 can use to indicate, to the AP device 1604, the maximum amount of time the client device 1602 may be in sleep mode before retrieving, for example, any buffered data (e.g., unicast, broadcast, or multicast data) from the AP device 1604.
  • any buffered data e.g., unicast, broadcast, or multicast data
  • the value in the Listen Interval field 1612 can be an integer value expressed in 2 octets (e.g., 16 bits).
  • the integer value can indicate the maximum number of beacon signals (and hence the maximum amount of time) that the client device 1602 can be in sleep mode.
  • a value of 20 in the Listen Interval field 1612 indicates to the AP device 1604 that the client device 1602 can be in sleep mode for as many as 20 beacon signals before requesting buffered unicast data to be communicated from the AP device 1604 to the client device 1602.
  • a value of 0 in the Listen Interval field 1612 can indicate to the AP device 1604 that the client device 1602 will not enter sleep mode and is available to receive all beacon signals transmitted by the AP device 1604.
  • the AP device 1604 can determine whether the client device 1602 is permitted to associate with the AP device 1604. In some instances, the AP device 1604 transmits an association response message 1614 to the client device 1602 in response to receiving the association request message 1608. In instances where the client device 1602 is permitted to associate with the AP device 1604, the association response message 1614 includes an association identifier (AID) field, which is used by the AP device 1604 to assign a unique identifier to the now associated client device 1602.
  • the value in the AID field of the association response message 1614 is unique for each associated client device and can be an integer value in the range of 1 to 2007 (both 1 and 2007 being included in the range).
  • the value in the AID field of the association response message 1614 can be used as an index into the TIM element of a beacon signal that is transmitted from the AP device 1604 to the client device 1602 after the client device 1602 is associated with the AP device 1604.
  • each beacon signal can include a TIM element.
  • FIG. 17 shows an example TIM element 1700.
  • the TIM element 1700 can be used by the AP device 1604 to identify the presence of buffered unicast, broadcast, or multicast data for the client device 1602.
  • the TIM element 1700 can be used by the AP device 1604 to indicate to each associated client device that the AP device 1604 has buffered unicast data for the respective client devices, and a beacon signal including a TIM element indicating the presence of buffered unicast data can be referred to as a TIM beacon signal.
  • the TIM element 1700 can be used by the AP device 1604 to indicate to each associated client device that the AP device 1604 has buffered broadcast or multicast data for the respective client devices.
  • a TIM element 1700 that indicates the presence of buffered broadcast or multicast data at the AP device 1604 can be referred to as a delivery traffic indication (DTIM) element, and a beacon signal including a DTIM element can be referred to as a DTIM beacon signal.
  • DTIM delivery traffic indication
  • the example TIM element 1700 includes multiple fields 1702, 1704, 1706, 1708, 1710, 1712.
  • the TIM element 1700 includes an element identification (ID) field 1702.
  • ID element identification
  • the element ID field 1702 is equal to 5.
  • the length field 1704 indicates the number of bytes in the TIM element 1700.
  • the DTIM count field 1706 is a countdown counter value that indicates the count until a DTIM beacon signal is scheduled to be sent.
  • the DTIM count field 1706 is decremented with each successive beacon signal transmitted by the AP device 1604.
  • the beacon signal is a DTIM beacon signal, and broadcast or multicast data may be scheduled to be transmitted by the AP device 1604 following (e.g., immediately following) the DTIM beacon signal.
  • the DTIM period field 1708 indicates the quantity of beacon signals to be transmitted by the AP device 1604 for each DTIM interval of time.
  • the partial virtual bitmap field 1712 is a variable length bit mask array (having a maximum of 251 bytes) indicating the presence of buffered data available from the AP device 1604.
  • the AP device 1604 may indicate the presence of the buffered data by setting to 1 the bit within the bit mask corresponding to the client device 1602. In some implementations, this bit within the bit mask may be described as a TIM value.
  • a bitmap control field 1710 can used to indicate which portion of the full traffic indication map (251 bytes) is sent via the partial virtual bitmap field 1712. In some instances, the bitmap control field 1710 can provide an indication of whether broadcast or multicast data is available for the client device 1602.
  • the AP device 1604 can transmit the broadcast or multicast data after (e.g., immediately after) transmitting the DTIM beacon signal. Consequently, one difference between a TIM beacon signal (e.g., indicating the presence of buffered unicast data for the respective client devices) and a DTIM beacon signal (e.g., indicating the presence of buffered broadcast or multicast data for the respective client devices) is that the AP device 1604 transmits buffered broadcast or multicast data to the respective client devices after (e.g., immediately after) the DTIM beacon signal. Consequently, a DTIM beacon signal can indicate to the client device 1602 that it needs to remain awake to receive the buffered broadcast or multicast data from the AP device 1604.
  • a TIM beacon signal e.g., indicating the presence of buffered unicast data for the respective client devices
  • a DTIM beacon signal e.g., indicating the presence of buffered broadcast or multicast data for the respective client devices
  • Legacy power save is a power save mechanism defined for use in one or more of the IEEE 802.11 family of standards that allows the client device 1602 to inform the AP device 1604 that it expects to enter a sleep mode and may, consequently, be unavailable to receive a given number of subsequent beacon signals from the AP device 1604.
  • the maximum number of beacon signals that the client device 1602 expects to be asleep through can be indicated by the Listen Interval field 1612 negotiated during association process (e.g., the example process 1600 shown in FIG. 16).
  • the client device 1602 may power down, but may be required to maintain a precise clock to ensure it powers up in time to receive a beacon signal from the AP device 1604.
  • the legacy power save mechanism makes use of a power management bit in a frame control field of a MAC header.
  • FIG. 18 shows an example MAC header 1800 having a frame control field 1802.
  • the frame control field 1802 includes a power management bit 1804.
  • the client device 1602 can indicate to the AP device 1604 that it expects to enter a sleep mode by transmitting a MAC layer message to the AP device 1604.
  • the MAC layer message can be a 0 payload length MAC frame (a Null Data Frame) where the power management bit 1804 is set to a first value (e.g., 1).
  • the AP device 1604 can buffer any unicast data for the client device 1602 and set the bit corresponding to the given AID in the TIM element 1700 indicating unicast data is queued.
  • the client device 1602 may sleep through the number of TIM beacon signals indicated in the Listen Interval field 1612, the client device 1602 may need to wake up for all DTIM beacon signals so that it can receive the broadcast or multicast data.
  • the client device 1602 can transmit a MAC layer message to the AP device 1604 with the power management bit 1804 set to a second, different value (e.g., 0), which indicates to the AP device 1604 that it may transmit any buffered data to the client device 1602.
  • a second, different value e.g., 0
  • the client device 1602 may transmit a power save polling (PS-POLL) message to the AP device 1604.
  • FIG. 19 shows an example format of a PS-POLL message 1900.
  • the PS-POLL message 1900 includes a frame control field 1902, a duration or AID field 1904, a basic service set identifier (BSSID) field 1906, a transmitter address (TA) field 1908, and a frame control sequence (FCS) field 1910.
  • BSSID basic service set identifier
  • TA transmitter address
  • FCS frame control sequence
  • the more data field 1806 of the MAC header 1800 may be set to 1. Subsequent data frames are then provided by the AP device 1604 to the client device 1602 one by one in the legacy power save mechanism.
  • an unscheduled automatic power save delivery (U-APSD) mechanism may be used as an enhancement to the legacy power save mechanism.
  • the U- APSD mechanism introduces the notion of Quality of Service (QoS), allowing an application to group messages into different categories depending on quality.
  • QoS Quality of Service
  • mechanisms may be added to allow the client device 1602 to wake up from sleep mode and request more than one message to be delivered (depending on the QoS indication) by the AP device 1604. Longer time windows may be allocated for higher priority data.
  • the U-APSD mechanism may be similar to the legacy power save mechanism, except that efficiency gains are made by the client device 1602 to retrieve buffered data from the AP device 1604.
  • wireless sensing may be based on a wireless communication device transmitting a set of wireless signals, which can be used to detect changes in the communication channel.
  • periodic measurements of the communication channel may be required for many sensing applications to detect changes in the communication channel.
  • a central coordinator e.g., residing on an AP device in some implementations
  • MIMO transmissions e.g., MIMO transmissions
  • the power save functionality present in one or more of the IEEE 802.11 family allow for power reduction for all types of wireless communication devices.
  • the power save functionality poses a challenge since wireless communication devices may suspend or power down wireless communication for an interval of time (typically under control of the device). Referring to FIG. 16. since the client device 1602 may not request data to be delivered for a duration defined by value in the Listen Interval field 1612, different client devices may sleep for different periods of time that is out of the control of the wireless network or AP device 1604.
  • queued data e.g., unicast queued data
  • Broadcast or multicast messages from the AP device 1604 can be used to elicit a transmission from the client device 1602.
  • use of broadcast or multicast messages for eliciting transmissions from the client device 1602 may be appealing since the client device 1602 may need to wake up to receive DTIM beacon signals, which is a network-controlled parameter. From an elicitation viewpoint it may also be more efficient if a single broadcast or multicast message could be used to generate multiple transmissions for the client device 1602.
  • the DTIM Period setting (e.g., in field 1708 in FIG.
  • the DTIM period may be typically set such that a DTIM beacon signal is transmitted every 2 or 3 beacons (e.g., every 204.8 ms or 307.2 ms, respectively), which may not be suitable for wireless sensing applications (which in some cases require periodic measurements with a rate of around 100 ms).
  • the ARP broadcast protocol may be leveraged to elicit periodic transmissions from the client device 1602 at a rate that would be suitable for wireless sensing applications.
  • some intelligent AP devices can implement a caching ARP service which can respond on behalf of a client device without the need for sending a broadcast transmission.
  • some client devices subscribe to multicast services without explicit user action or the install of extra software.
  • these constraints post a challenge for schemes that make use of a deterministic wakeup to receive the DTIM beacon signal and broadcast or multicast messages.
  • There are services such as multicast Domain Name System (mDNS) or DNS service discovery (DNS-SD), which operate using broadcast or multicast messaging, however their usage is just beginning to become more common among common IoT devices. Therefore, a mechanism may be needed to prevent specific client devices from entering sleep mode.
  • mDNS multicast Domain Name System
  • DNS-SD DNS service discovery
  • a decision for a client device to enter power save mode may be made at one or more layers in an OSI model (e.g., shown in FIG. 7).
  • a network implementer can make the decision as to which of the layer(s) in the OSI model may be used to decide whether a client device enters a power save mode.
  • the main criteria used is based on whether the client device has data (e.g., at the given layer) to transmit or the frequency or type of data that is being received by the client device.
  • the processes described above in relation to FIGS. 9, 10, 11A to llC, 12A, 12B, and 13 can utilize existing protocols which are present on off-the-shelf client devices and can operate without any user configuration or the install of extra software. Furthermore, the messages that are communicated in an efficient manner using the existing protocols and have small overhead (e.g., as shown in FIG. 8) in the elicitation of a transmission.
  • the processes shown in FIGS. 9, 10, 11A to 11C, 12A, 12B, and 13 can be used to elicit MIMO transmissions to that PHY preamble training fields in the MIMO transmissions can be used to detect changes in the communication channel. Additionally or alternatively, the processes shown in FIGS. 9, 10, 11A to 11C, 12A, 12B, and 13 can be used to prevent a wireless communication device (e.g., a client device) from entering a sleep mode. Specifically, the rate at which elicitations are requested can be programmable such that a minimum is achieved. A programmable elicitation rate can prevent a wireless communication device from entering a sleep mode and can reduce the load added to the network and device.
  • a wireless communication device e.g., a client device
  • the programmable elicitation rate can be provided as an input to one or more of the processes shown in FIGS. 11A to 11C, 12A, 12B, and 13.
  • the programmable elicitation rate can be used by the timer of the wireless communication device during timer setup in operations 1101, 1205, 1303 in FIGS. 11A, 12A, and 13, respectively (e.g., the timer can be setup so that transmissions are elicited at the programmed elicitation rate).
  • the programmable elicitation rate can be used by the timer of the wireless communication device during the timer tick operation 1123 shown in FIG.
  • each timer tick can be asserted at a rate that is substantially equal to the programmed elicitation rate.
  • the programmable elicitation rate can be used in operations 1221 and 1223 shown in FIG. 12B.
  • FIG. 20 shows an example control loop 2000 that can be used to vary the rate at which transmissions are elicited.
  • the example control loop 2000 can be used to ensure that the rate at which transmissions are elicited is greater than a minimum value, which in turn can prevent a wireless communication device from entering a sleep mode and can reduce the load added to the network and device.
  • the example control loop 2000 includes a first wireless communication device 2002 and a second wireless communication device 2004.
  • the first wireless communication device 2002 transmits a message 2003 (e.g. a network or transport layer message) that is addressed to the second wireless communication device 2004.
  • the message 2003 may be transmitted in response to one or more of elicitation processes 2006A, 2006B.
  • the elicitation process 2006A may be one or more of the processes described above in relation to FIGS. 9, 10, 11A to 11C, 12A, 12B, and 13.
  • the message 2003 may be higher layer data traffic.
  • the elicitation process 2006B can be an optional or additional elicitation process.
  • the elicitation process 2006B can be an asynchronous subsystem or a state machine that is implemented separately from the process 2006A.
  • the elicitation process 2006B may be configured to independently generate messages 2003 (e.g., leveraging a MAC protocol) for transmission to the second wireless communication device 2004.
  • the response from the second wireless communication device 2004 can be used by the first wireless communication device 2002 to generate channel information (e.g., channel state information), which in turn can be used to detect changes in the communication channel.
  • channel information e.g., channel state information
  • An example of the elicitation process 2006B is a state machine implemented within the MAC and/or PHY layers, which does not require the use of higher layer protocols. This state machine could even include components or subsystems defined by the IEEE 802.11 family of standards.
  • the elicitation process 2006B can be an optional or additional elicitation process.
  • the elicitation process 2006B operates independently from the elicitation process 2006A.
  • the elicitation process 2006B generates elicitation messages 2003 at a rate that is suitable for wireless sensing applications and that prevents the first wireless communication device 2002 from entering sleep mode. For example, in instances where the wireless sensing application operates on channel information that is generated every 100 ms, the elicitation process 2006B can generate the message 2003 every 100 ms.
  • One feature of using the elicitation process 2006B is that the messages 2003 generated by the elicitation process 2006B causes the second wireless communication device 2004 to generate respective responses 2005, which can be used to generate channel information, while the responses to messages generated by the elicitation process 2006A are not used to generate channel information, but rather to prevent the device from entering a power savings mode.
  • the elicitation process 2006B can be an optional or additional elicitation process.
  • the elicitation process 2006A can be used to generate messages 2003 that can be used for both preventing the first wireless communication device 2002 from entering sleep mode and generating channel information (e.g., channel state information) that can be used to detect changes in the communication channel.
  • channel information e.g., channel state information
  • a transmitter of the first wireless communication device 2002 communicates the message 2003 to the second wireless communication device 2004.
  • the second wireless communication device 2004 is a Wi-Fi client device having a Wi-Fi subsystem 2008 (which includes a radio subsystem and a baseband subsystem).
  • the transmitter of the first wireless communication device 2002 may have IEEE 802.11 compliant features.
  • the second wireless communication device 2004 may further include device higher layer logic circuits 2010.
  • the device higher layer logic circuits 2010 execute decision logic to determine whether the second wireless communication device 2004 enter sleep mode.
  • the criteria for entering sleep mode may be implementation specific, and in some instances could be based on the rate of data exchange between the Wi-Fi subsystem 2008 and the device higher layer logic circuits 2010.
  • the second wireless communication device 2004 may not enter sleep mode when there is a high rate of data exchange between the Wi-Fi subsystem 2008 and the device higher layer logic circuits 2010.
  • the second wireless communication device 2004 sends a response transmission (e.g., a MIMO transmission) that traverses a space between the first and second wireless communication devices 2002, 2004.
  • the response transmission is received by a receiver of the first wireless communication device 2002.
  • the receiver of the first wireless communication device 2002 generates channel information (e.g., channel state information) for each response transmission that is received from the second wireless communication device 2004.
  • the channel information can be generated based on one or more training fields in each of the response transmissions received from the second wireless communication device 2004.
  • the channel information is generated for each response transmission that is received from the second wireless communication device 2004, the channel information is generated at some rate, which can be measured using rate measurement circuitry 2012.
  • the rate measurement circuitry 2012 determines an average number of times channel information is generated over a programmable time interval (indicated in FIG. 20 as an integration interval). In some instances, the integration interval is about 10 seconds.
  • the rate at which the channel information is generated is compared against an expected rate (e.g., in difference block 2014).
  • the expected rate can be the minimum rate at which response transmissions need to be elicited to prevent a wireless communication device from entering a sleep mode.
  • the difference block 2014 performs a subtraction between the measured rate (e.g., output of rate measurement circuitry 2012) and the expected rate, and the difference is provided to a rate selection block 2016 that initially selects and subsequently varies the rate at which elicitation messages 2003 are transmitted from the first wireless communication device 2002 to the second wireless communication device 2004 (e.g., based on the difference provided to the rate selection block 2016 by the difference block 2014).
  • the initial rate at which elicitation messages 2003 are transmitted from the first wireless communication device 2002 to the second wireless communication device 2004 may be based on an initial value 2018.
  • the initial value 2018 may be a system-defined value or a user-defined value.
  • the initial value 2018 may be substantially equal to the expected rate (e.g., shown in difference block 2014). If the output produced by the difference block 2014 indicates that channel information is being generated at a rate that is less than the expected rate, the rate selection block increases the rate at which the elicitation messages 2003 are transmitted from the first wireless communication device 2002 to the second wireless communication device 2004, up to a maximum rate 2020.
  • the maximum rate 2020 may be selected based on external factors, such as network load, or device load.
  • the maximum rate 2020 is set to around 40 ms.
  • the output of the rate selection block 2016 (representing the updated rate at which the elicitation messages 2003 are transmitted) may then be provided as an input to one or more of the processes shown in FIGS. 11A to 11C, 12A, 12B, and 13.
  • FIG. 21 shows a flowchart representing an example method 2100 of varying a rate of eliciting MIMO transmissions from wireless communication devices.
  • the method 2100 illustrates a general operation of the control loop 2000 shown in FIG. 20.
  • the process 2100 may include additional or different operations, and the operations shown in FIG. 21 may be performed in the order shown or in another order.
  • one or more of the operations shown in FIG. 21 are implemented as processes that include multiple operations, sub-processes for other types of routines.
  • operations can be combined, performed in another order, performed in parallel, iterated or otherwise repeated or performed in another manner.
  • the process 2100 may be performed by the example wireless communication devices 102A, 102B, 102C shown in FIG.
  • the process 2100 may be performed by a wireless communication device that seeks to elicit MIMO transmissions from another wireless communication device.
  • a first set of messages is wirelessly transmitted at a first transmission rate to the device from which MIMO transmissions are sought.
  • the first set of messages can be first network layer messages, which may be generated and transmitted according to the ICMP ping process (e.g., described in FIGS. 11A, 11B, 11C), the ARP ping process (e.g., described in FIG. 13), or a combination thereof.
  • the first network layer messages may be encapsulated into the payload field of respective Media Access Control (MAC) layer messages.
  • MAC Media Access Control
  • the first set of messages can, additionally or alternatively, be first transport layer messages, which may be generated and transmitted according to the TCP ping process (e.g., described in FIGS. 12A, 12B). As described in FIG. 8, the first transport layer messages that may be generated may be encapsulated into the payload field of respective network layer messages.
  • the network or transport layer messages maybe addressed to the device from which MIMO transmissions are sought.
  • the address of the device from which MIMO transmissions are sought may be an upper layer logical address (e.g., network address) of the device and may be obtained using the process described in FIG. 10.
  • MIMO transmissions are received from the device.
  • the MIMO transmissions can include MIMO training fields.
  • the MIMO training fields contain signals (e.g., CSI) having a higher frequency resolution, a greater number of subcarrier frequencies, and a higher frequency bandwidth compared to Legacy training fields in the PHY frame.
  • a training field is identified in each MIMO transmission, and channel information is generated based on the training field (at 2108).
  • the rate at which the channel information is generated is determined (e.g., using rate measurement circuitry 2012 shown in FIG. 20).
  • the first transmission rate is changed to a second, different transmission rate based on the rate at which the channel information is generated (e.g., using difference block 2014 and rate selection block 2016 shown in FIG. 20).
  • a second set of messages e.g., a second set of network or transport layer messages
  • Some of the subject matter and operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them.
  • Some of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on a computer storage medium for execution by, or to control the operation of, data-processing apparatus.
  • a computer storage medium can be, or can be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them.
  • a computer storage medium is not a propagated signal
  • a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal.
  • the computer storage medium can also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).
  • the term "data-processing apparatus” encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing.
  • the apparatus can include special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).
  • the apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross platform runtime environment, a virtual machine, or a combination of one or more of them.
  • a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment.
  • a computer program may, but need not, correspond to a file in a file system.
  • a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
  • a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
  • Some of the processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output.
  • the processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).
  • a computer having a display device (e.g., a monitor, or another type of display device) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse, a trackball, a tablet, a touch sensitive screen, or another type of pointing device) by which the user can provide input to the computer.
  • a display device e.g., a monitor, or another type of display device
  • a keyboard and a pointing device e.g., a mouse, a trackball, a tablet, a touch sensitive screen, or another type of pointing device
  • Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.
  • a computer can interact with a user by sending documents to and receiving documents from a device that is used
  • MIMO transmissions are elicited from wireless communication devices and for wireless sensing.
  • a wireless sensing system e.g., a motion detection system
  • the message is addressed to, and wirelessly transmitted to, a second wireless communication device.
  • the second wireless communication device sends a MIMO transmission that traverses a space between the first and second wireless communication devices.
  • the first wireless communication device senses the space (e.g., detects motion of an object in the space) based on the MIMO transmissions.
  • a first wireless communication device obtains a network layer address of a second wireless communication device; addresses network layer messages to the network layer address of the second wireless communication device; initiates wireless transmission of the network layer messages; in response to the network layer messages, receives MIMO transmissions from the second wireless communication device, where the MIMO transmissions traverse a space between the first and second wireless communication devices; generates a series of channel responses based on a training field in the MIMO transmissions; and detects motion of an object in the space based on the series of channel responses.
  • Implementations of the first example may include one or more of the following features.
  • the network layer messages can be sent according to an ICMP Ping process, an ARP ping process, or another type of process.
  • the MIMO training field can be an HE-LTF, VHT-LTF or an HT-LTF.
  • the wireless sensing may include detecting motion of an object in the space.
  • a first wireless communication device generates a transport layer message addressed to a second wireless communication device; initiates wireless transmission of the transport layer messages; in response to the transport layer messages, receives MIMO transmissions from the second wireless communication device, where the MIMO transmissions traverse a space between the first and second wireless communication devices; generates a series of channel responses based on a training field in the MIMO transmissions; and performs wireless sensing of the space based on the series of channel responses.
  • Implementations of the second example may include one or more of the following features.
  • the transport layer messages can be sent according to a TCP Ping process, or another type of process.
  • the MIMO training field can be an HE-LTF, VHT-LTF or an HT-LTF.
  • the wireless sensing may include detecting motion of an object in the space.
  • a first wireless communication device initiates a first mechanism to elicit a MIMO transmission from a second wireless communication device, and detects a failure of the first mechanism; initiates a second, different mechanism to elicit a MIMO transmission from the second wireless communication device, and detects a success of the second mechanism; generates a series of channel responses based on MIMO transmissions elicited from the second device using the second mechanism; and performs wireless sensing based on the series of channel responses.
  • Implementations of the third example may include one or more of the following features.
  • the first mechanism and the second mechanism may include an ICMP Ping, a TCP Ping, an ARP Ping, or another type of request/response process.
  • the fist wireless communication device may initiate the first mechanism and the second mechanism (and possibly additional mechanisms) based on a state of a state machine.
  • the wireless sensing may include detecting motion of an object in a space traversed by the MIMO transmissions.
  • a first wireless communication device in a wireless communication network may: generate network or transport layer messages addressed to a second wireless communication device in the wireless communication network; wirelessly transmit the network or transport layer messages to the second wireless communication device to elicit multiple-input-multiple-output (MIMO) transmissions from the second wireless communication device; and receive MIMO transmissions from the second wireless communication device.
  • MIMO transmissions may traverse a space between the first wireless communication device and the second wireless communication device.
  • the first wireless communication device may also identify a training field in each MIMO transmission; generate channel information based on the respective training fields; and detect motion that occurred in the space based on the channel information.
  • Implementations of the fourth example may include one or more of the following features.
  • the network or transport layer messages includes network layer messages encapsulated into a payload field of respective Media Access Control (MAC) layer messages.
  • the network layer messages are wirelessly transmitted according to an Internet Control Message Protocol (ICMP) Ping process.
  • the first wireless communication device may further obtain a network layer address of the second wireless communication device; and encapsulate the network layer address of the second wireless communication device into the payload field of the respective MAC layer messages.
  • ICMP Internet Control Message Protocol
  • the network or transport layer messages include transport layer messages encapsulated into a payload field of respective network layer messages, and the transport layer messages are wirelessly transmitted according to a Transmission Control Protocol (TCP) Ping process, an Address Resolution Protocol (ARP) Ping addressed to the second wireless communication device, or a combination thereof.
  • the first wireless communication device may further detect a failure of the network or transport layer messages to elicit MIMO transmissions from the second wireless communication device; in response to detecting the failure, generate second network or transport layer messages addressed to the second wireless communication device; and wirelessly transmit the second network or transport layer messages to the second wireless communication device to elicit MIMO transmissions from the second wireless communication device.
  • the network or transport layer messages are wirelessly transmitted according to a first type of communication process, and the second network or transport layer messages are wirelessly transmitted according to a second, different type of communication process.
  • the first type of communication process and the second type of communication process are selected from the group consisting of an ICMP Ping, an ARP Ping addressed to the second wireless communication device, and a TCP Ping.
  • Identifying the training field in each MIMO transmission includes identifying the training field in a PHY frame of each MIMO transmission.
  • a non-transitory computer-readable medium stores instructions that are operable when executed by data processing apparatus to perform one or more operations of the first example, the second example, the third example, or the fourth example.
  • a system includes a plurality of wireless communication devices, and a device configured to perform one or more operations of the first example, the second example, the third example, or the fourth example.
  • Implementations of the sixth example may include one or more of the following features.
  • One of the wireless communication devices can be or include the device.
  • the device can be located remote from the wireless communication devices.
  • a rate at which multiple-input/multiple-output (MIMO) transmissions are elicited from wireless communication devices is varied (e.g., to prevent the wireless communication devices from entering a sleep / power-saving mode).
  • a first wireless communication device wirelessly transmits a first set of messages at a first transmission rate to a second wireless communication device to elicit first multiple-input-multiple-output (MIMO) transmissions from the second wireless communication device.
  • the first wireless communication device also receives the first MIMO transmissions from the second wireless communication device, where the first MIMO transmissions traverse a space between the first wireless communication device and the second wireless communication device.
  • the first wireless communication device further generates first channel information based on respective training fields identified in each of the first MIMO transmissions; determines a rate at which the first channel information is generated; and varies the first transmission rate to a second, different transmission rate based on the rate at which the first channel information is generated.
  • the first wireless communication device additionally wirelessly transmits a second set of messages at the second transmission rate to the second wireless communication device to elicit second MIMO transmissions from the second wireless communication device.
  • Implementations of the seventh example may include one or more of the following features. Varying the first transmission rate to the second transmission rate includes: comparing the rate at which the first channel information is generated to a threshold, the threshold being a minimum transmission rate to prevent the second wireless communication device from entering a power saving mode; and increasing the first transmission rate to the second transmission rate in response to the rate at which the first channel information is generated being less than the threshold.
  • the first set of messages includes a first set of network or transport layer messages
  • the second set of messages includes a second set of network or transport layer messages. At least one of the first set of network or transport layer messages or the second set of network or transport layer messages includes network layer messages encapsulated into a payload field of respective Media Access Control (MAC) layer messages.
  • MAC Media Access Control
  • the network layer messages are wirelessly transmitted according to an Internet Control Message Protocol (ICMP) Ping process. At least one of the first set of network or transport layer messages or the second set of network or transport layer messages includes transport layer messages encapsulated into a payload field of respective network layer messages.
  • the transport layer messages are wirelessly transmitted according to a Transmission Control Protocol (TCP) Ping process, an Address Resolution Protocol (ARP) Ping addressed to the second wireless communication device, or a combination thereof.
  • TCP Transmission Control Protocol
  • ARP Address Resolution Protocol

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Abstract

Dans un aspect général, un débit auquel des transmissions MIMO sont déclenchées à partir de dispositifs de communication sans fil est amené à varier. Un premier dispositif de communication sans fil peut être configuré pour transmettre sans fil un premier ensemble de messages à un premier débit de transmission à un second dispositif de communication sans fil. Le premier dispositif de communication sans fil peut en outre être configuré pour recevoir des transmissions MIMO à partir du second dispositif de communication sans fil. Le premier dispositif de communication sans fil peut en outre être configuré pour générer des premières informations de canal sur la base de champs d'apprentissage respectifs dans chacune des premières transmissions MIMO ; déterminer un débit auquel les premières informations de canal sont générées ; faire varier le premier débit de transmission à un second débit de transmission différent sur la base du débit auquel les premières informations de canal sont générées ; et transmettre sans fil un second ensemble de messages au second débit de transmission au second dispositif de communication sans fil.
EP22809989.1A 2021-05-24 2022-05-12 Variation d'un débit de déclenchement de transmissions mimo à partir de dispositifs de communication sans fil Pending EP4348855A4 (fr)

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