阅读说明：本技术 基于双向信道探测的运动检测和定位 (Motion detection and localization based on bi-directional channel sounding ) 是由 O·克拉维茨 T·曼库 于 2018-12-03 设计创作，主要内容包括：在所描述的示例的一般方面中,基于双向信道探测来检测运动。在示例中,从第一装置获得第一信道信息集。第一信道信息集是基于在某个时间帧中的第一时间从第二装置发送通过空间的第一无线信号集。从第二装置获得第二信道信息集。第二信道信息集是基于在该时间帧中的第二时间从第一装置发送通过空间的第二无线信号集。分析第一信道信息集和第二信道信息集以在该时间帧期间在空间中检测运动的类别或所检测到的运动的位置。(In a general aspect of the described examples, motion is detected based on bi-directional channel sounding. In an example, a first set of channel information is obtained from a first apparatus. The first set of channel information is a first set of wireless signals transmitted through space from a second apparatus based on a first time in a certain time frame. A second set of channel information is obtained from a second apparatus. The second set of channel information is a second set of wireless signals transmitted through the space from the first apparatus based on a second time in the time frame. The first set of channel information and the second set of channel information are analyzed to detect a category of motion or a location of the detected motion in space during the time frame.)

1. A method for motion detection, comprising:

obtaining, from a first apparatus, a first set of channel information, the first set of channel information being based on a first set of wireless signals transmitted through space from a second apparatus at a first time in a certain time frame;

obtaining a second set of channel information from the second apparatus, the second set of channel information being a second set of wireless signals transmitted through the space from the first apparatus based on a second time in the time frame; and

analyzing the first set of channel information and the second set of channel information to detect a category of motion or a location of the detected motion in the space during the time frame.

2. The method of claim 1, wherein the first set of channel information and the second set of channel information are based on wireless signals transmitted bi-directionally between the first apparatus and the second apparatus through the space.

3. The method of claim 1, wherein the wireless signal comprises a reference signal or a beacon signal.

4. The method of claim 1, wherein the first set of wireless signals is transmitted from the first apparatus to the second apparatus in a first direction, and the second set of wireless signals is transmitted from the second apparatus to the first apparatus in a second direction.

5. The method of any of claims 1-4, wherein analyzing the first set of channel information and the second set of channel information comprises: comparing the first set of channel information with the second set of channel information to determine whether an object is moving in an area proximate to the first apparatus or the second apparatus.

6. The method of claim 5, wherein determining whether an object is moving in an area proximate to the first device or the second device comprises:

determining that an object is moving in an area near the first apparatus if the first set of channel information indicates more channel variation over time than the second set of channel information; or

Determining that an object is moving in an area near the second apparatus when the second set of channel information indicates more channel variation over time than the first set of channel information.

7. The method of any of claims 1-4, wherein analyzing the first set of channel information and the second set of channel information comprises: determining that an object is moving in an area between the first apparatus and the second apparatus when the first set of channel information indicates similar channel variations over time as compared to the second set of channel information.

8. The method of any of claims 1-4, wherein analyzing the first set of channel information and the second set of channel information comprises determining a category of motion.

9. The method of claim 8, wherein determining a category of motion comprises identifying a type of moving object.

10. The method of any of claims 1-4, wherein analyzing the first set of channel information and the second set of channel information comprises:

determining that a small object is moving closer to the first apparatus than to the second apparatus if the first set of channel information indicates less channel disturbances over time than a second set of channel disturbances; or

Determining that a large object is moving closer to the second apparatus than to the first apparatus if the first set of channel information indicates greater channel disturbances over time than the second set of channel disturbances.

11. A motion detection apparatus comprising one or more processors and memory, the memory comprising instructions that when executed by the one or more processors cause wireless communication to:

obtaining, from a first apparatus, a first set of channel information, the first set of channel information being based on a first set of wireless signals transmitted through space from a second apparatus at a first time in a certain time frame;

obtaining a second set of channel information from the second apparatus, the second set of channel information being a second set of wireless signals transmitted through the space from the first apparatus based on a second time in the time frame; and

analyzing the first set of channel information and the second set of channel information to detect a category of motion or a location of the detected motion in the space during the time frame.

12. The apparatus of claim 11, wherein the first set of channel information and the second set of channel information are based on wireless signals transmitted bi-directionally between the first apparatus and the second apparatus through the space.

13. The apparatus of claim 11, wherein the wireless signal comprises a reference signal or a beacon signal.

14. The apparatus of claim 11, wherein the first set of wireless signals is transmitted from the first apparatus to the second apparatus in a first direction, and the second set of wireless signals is transmitted from the second apparatus to the first apparatus in a second direction.

15. The apparatus of any of claims 11-14, wherein analyzing the first set of channel information and the second set of channel information comprises: comparing the first set of channel information with the second set of channel information to determine whether an object is moving in an area proximate to the first apparatus or the second apparatus.

16. The apparatus of claim 15, wherein determining whether an object is moving in an area proximate to the first apparatus or the second apparatus comprises:

determining that an object is moving in an area near the first apparatus if the first set of channel information indicates more channel variation over time than the second set of channel information; or

Determining that an object is moving in an area near the second apparatus when the second set of channel information indicates more channel variation over time than the first set of channel information.

17. The apparatus of any of claims 11-14, wherein analyzing the first set of channel information and the second set of channel information comprises: determining that an object is moving in an area between the first apparatus and the second apparatus when the first set of channel information indicates similar channel variations over time as compared to the second set of channel information.

18. The apparatus of any of claims 11-14, wherein analyzing the first set of channel information and the second set of channel information comprises determining a category of motion.

19. The apparatus of claim 18, wherein determining a category of motion comprises identifying a type of moving object.

20. The apparatus of any of claims 11-14, wherein analyzing the first set of channel information and the second set of channel information comprises:

determining that a small object is moving closer to the first apparatus than to the second apparatus if the first set of channel information indicates less channel disturbances over time than a second set of channel disturbances;

determining that a large object is moving closer to the second apparatus than to the first apparatus if the first set of channel information indicates greater channel disturbances over time than the second set of channel disturbances.

21. A computing system for motion detection, comprising:

a data processing device;

a memory for storing instructions that are executable when executed by the data processing apparatus to:

obtaining a first set of channel information from a first wireless communication device, the first set of channel information being a first set of wireless signals transmitted through space from a second wireless communication device based on a first time in a certain time frame;

obtaining a second set of channel information from the second wireless communication device, the second set of channel information being based on a second set of wireless signals transmitted through the space from the first wireless communication device at a second time in the time frame; and

analyzing the first set of channel information and the second set of channel information to detect a category of motion or a location of the detected motion in the space during the time frame.

22. The system of claim 21, wherein the first set of channel information and the second set of channel information are based on wireless signals transmitted bi-directionally through the space between the first wireless communication device and the second wireless communication device.

23. The system of claim 21, wherein the wireless signal comprises a reference signal or a beacon signal.

24. The system of claim 21, wherein the first set of wireless signals is transmitted from the first wireless communication device to the second wireless communication device in a first direction, and the second set of wireless signals is transmitted from the second wireless communication device to the first wireless communication device in a second direction.

25. The system of any of claims 21 to 24, wherein analyzing the first set of channel information and the second set of channel information comprises: comparing the first set of channel information with the second set of channel information to determine whether an object is moving in an area proximate the first wireless communication device or the second wireless communication device.

26. The system of claim 25, wherein determining whether an object is moving in an area proximate to the first wireless communication device or the second wireless communication device comprises:

determining that an object is moving in an area near the first wireless communication apparatus when the first set of channel information indicates more channel variation over time than the second set of channel information; or

Determining that an object is moving in an area near the second wireless communication apparatus when the second channel information set indicates more channel variation with the passage of time than the first channel information set.

27. The system of any of claims 21 to 24, wherein analyzing the first set of channel information and the second set of channel information comprises: when the first channel information set indicates similar channel changes over time as compared to the second channel information set, it is determined that an object is moving in an area between the first wireless communication apparatus and the second wireless communication apparatus.

28. The system of any of claims 21 to 24, wherein analyzing the first set of channel information and the second set of channel information comprises determining a category of motion.

29. The system of claim 28, wherein determining a category of motion comprises identifying a type of moving object.

30. The system of any of claims 21 to 24, wherein analyzing the first set of channel information and the second set of channel information comprises:

determining that a small object is moving closer to the first wireless communication device than to the second wireless communication device if the first set of channel information indicates less channel disturbances over time than a second set of channel disturbances;

determining that a large object is moving closer to a second wireless communication device than to the first wireless communication device if the first set of channel information indicates greater channel disturbances over time than the second set of channel disturbances.

Background

The following description relates to motion detection.

Motion detection systems have been used to detect movement of objects in, for example, a room or outdoor area. In some exemplary motion detection systems, infrared or optical sensors are used to detect movement of objects in the field of view of the sensor. Motion detection systems have been used in security systems, automated control systems, and other types of systems.

Drawings

Fig. 1 is a diagram illustrating an exemplary wireless communication system.

Fig. 2A and 2B are diagrams illustrating exemplary wireless signals communicated between wireless communication devices.

Fig. 3A and 3B are diagrams of an exemplary motion detection system.

Fig. 4A and 4B are diagrams of an exemplary motion detection system based on bi-directional channel sounding.

Fig. 5A and 5B are diagrams illustrating exemplary motion localization areas in a motion detection system.

FIG. 6 is a flow diagram illustrating an exemplary process for detecting motion of an object in space based on bi-directional channel sounding.

Detailed Description

In some aspects described herein, motion in space may be detected based on bi-directional channel sounding. Channel sounding may refer to evaluating a radio environment and monitoring wireless channel state information over time where a first wireless device transmits a wireless signal (e.g., a reference signal) having known characteristics and a second wireless device receives the transmitted signal and analyzes the effect of the channel on the transmitted signal (since the characteristics of the transmitted signal are known). Bidirectional channel sounding may refer to channel sounding by a wireless communication device in both directions (e.g., sequentially). For example, in some implementations, a channel is probed from a first wireless device (TX) towards a second wireless device (RX), and thereafter the channel is probed from the second wireless device (TX) towards the first wireless device (RX). The two-way channel sounding may be performed in a time frame that is small to be negligible from a human kinematics point of view, e.g. on the order of milliseconds (ms), so that measurements performed in each direction may be compared to each other.

The channel information from the two wireless devices may then be communicated to a designated device (e.g., a wireless device designated as a hub, a master wireless device, a server communicatively coupled to the wireless device (e.g., in the cloud), or other device). The channel information may include measured Channel State Information (CSI), such as channel responses, etc., or may include beamforming steering state information, such as steering or feedback matrices generated according to the IEEE802.11ac-2013 standard, which is incorporated herein by reference. CSI may refer to known channel characteristics of a communication link and may describe how a wireless signal propagates from a transmitter to a receiver, representing, for example, the combined effects of scattering, fading, and power attenuation in the space between the transmitter and the receiver. Beamforming (or spatial filtering) may refer to signal processing techniques used in multi-antenna (multiple-input/multiple-output (MIMO)) radio systems for directional signal transmission or reception. Beamforming may be achieved by combining elements in an antenna array in such a way that signals at a particular angle undergo constructive interference, while other signals undergo destructive interference. Beamforming may be used at both the transmitting and receiving ends to achieve spatial selectivity. In some cases (e.g., IEEE802.11ac standard), the transmitter uses a beamforming steering matrix. The beamforming matrix may include a mathematical description of how the antenna array should use its individual antenna elements to select spatial paths for transmission. Although certain aspects are described herein with respect to channel state information, beamforming state information or beamforming steering matrix states may also be used in the described aspects.

Then, the specifying device analyzes the information transmitted from these devices to detect whether or not a motion occurs in the space through which the wireless signal passes. For example, a given device may analyze channel state information or beamforming state information provided by two or more wireless devices to detect whether a channel change has occurred, which may be due to motion of an object in space. In some cases, the designated device may analyze whether there is a substantial difference between the measurement information from the wireless devices. The analysis may be used to determine the location of the detected motion. For example, if the first wireless device reports a much larger detected channel change than the second wireless device, the designated device may determine that the object is moving closer to the second wireless device. Similarly, if the first wireless device reports a much smaller detected channel change than the second wireless device, the designation device may determine that the object is moving closer to the first wireless device. It is also possible to determine the state between these two states (close to one sensor and close to the other). For example, if the detected channel variations are approximately the same for two wireless devices, the designated device may determine that the detected motion occurred in the "middle zone" between the two devices.

Bidirectional channel sounding may also be used to provide a confidence level for motion sounding, and may allow false positive detection to be more effectively suppressed (e.g., where one of the wireless devices erroneously "detects" motion due to non-environmental changes such as radio interference, noise, or system-induced measurement impairments). In this case, if one wireless device is reporting motion and another wireless device is not (for a certain period of time; a particular temporal signature or other metric may apply), the designated device may provide a determination that no motion has occurred in the space.

In some instances, aspects of the present disclosure may provide one or more advantages. For example, motion may be detected based on wireless signals without line of sight between devices and with fewer false positives. Motion may be detected using existing wireless communication devices and networks. Additionally, the location of the detected motion may be determined.

Fig. 1 illustrates an exemplary wireless communication system 100. The exemplary wireless communication system 100 includes three wireless communication devices-a first wireless communication device 102A, a second wireless communication device 102B, and a third wireless communication device 102C. The exemplary wireless communication system 100 may include additional wireless communication devices and other components (e.g., additional wireless communication devices, one or more network servers, network routers, network switches, cables or other communication links, etc.).

Examples of wireless communication devices 102A, 102B, 102C may operate in a wireless network, e.g., according to a wireless network standard or other type of wireless communication protocol, for example, a wireless network may be configured to operate as a wireless local area network (W L AN), a Personal Area Network (PAN), a Metropolitan Area Network (MAN), or other type of wireless network, examples of W L AN include networks configured to operate according to one or more standards of the 802.11 family of standards developed by IEEE, etc. (e.g., Wi-Fi networks), etc.Near Field Communication (NFC), ZigBee), millimeter wave communication, and the like.

Examples of 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 (L TE) and advanced L TE (L TE-A), and so forth.

In the example shown in fig. 1, the wireless communication devices 102A, 102B, 102C may be or may include standard wireless network components, for example, the wireless communication devices 102A, 102B, 102C may be commercially available Wi-Fi access points or other types of Wireless Access Points (WAPs) that perform one or more operations as described herein embedded as instructions (e.g., software or firmware) on a modem of the WAP.

As shown in fig. 1, exemplary wireless communication device 102C includes a modem 112, a processor 114, a memory 116, and a power supply unit 118; any of the wireless communication devices 102A, 102B, 102C in the wireless communication system 100 may include the same, additional, or different components, and these components may be configured to operate as shown in fig. 1 or otherwise. In some implementations, the modem 112, processor 114, memory 116, and power supply unit 118 of the wireless communication device are housed together in a common housing or other assembly. In some implementations, one or more components of the wireless communication device may be housed separately, e.g., in a separate housing or other assembly.

The exemplary modem 112 may communicate (receive, transmit, or both) wireless signals. For example, modem 112 may be configured to communicate Radio Frequency (RF) signals formatted according to a wireless communication standard (e.g., Wi-Fi or bluetooth). The modem 112 may be implemented as the exemplary wireless network modem 112 shown in fig. 1, or may be implemented in other ways (e.g., with other types of components or subsystems). In some implementations, the example modem 112 includes a radio subsystem and a baseband subsystem. In some cases, the baseband subsystem and the radio subsystem may be implemented on a common chip or chipset, or they may be implemented in a card or other type of assembly device. The baseband subsystem may be coupled to the radio subsystem, for example, by wires, pins, wiring, or other types of connections.

In some cases, the radio subsystem in modem 112 may include radio frequency circuitry and one or more antennas. The radio frequency circuitry may include, for example, circuitry for filtering, amplifying, or otherwise conditioning an analog signal, circuitry for up-converting a baseband signal to an RF signal, circuitry for down-converting an RF signal to a baseband signal, etc. Such circuitry may include, for example, filters, amplifiers, mixers, local oscillators, and so forth. The radio subsystem may be configured to communicate radio frequency wireless signals over a wireless communication channel. By way of example, the radio subsystem may include a radio chip, an RF front end, and one or more antennas. The radio subsystem may include additional or different components. In some implementations, the radio subsystem may be or include radio electronics (e.g., an RF front end, a radio chip, or similar component) from a conventional modem (e.g., from a Wi-Fi modem, a pico base station modem, etc.). In some implementations, the antenna includes a plurality of antennas.

In some cases, the baseband subsystem in modem 112 may, for example, include digital electronics configured to process digital baseband data. As an example, the baseband subsystem may include a baseband chip. The baseband subsystem may include additional or different components. In some cases, the baseband subsystem may include a Digital Signal Processor (DSP) device or other type of processor device. In some cases, the baseband system includes digital processing logic to operate the radio subsystem, to communicate wireless network traffic through the radio subsystem, to detect motion based on motion detection signals received through the radio subsystem, or to perform other types of processing. For example, the baseband subsystem may include one or more chips, chipsets, or other types of devices configured to encode signals and communicate the encoded signals to the radio subsystem for transmission, or to identify and analyze data encoded in the signals from the radio subsystem (e.g., by decoding the signals according to a wireless communication standard, by processing the signals according to a motion detection process, or otherwise).

In some examples, the radio subsystem in the example modem 112 receives baseband signals from the baseband subsystem, upconverts the baseband signals to Radio Frequency (RF) signals, and wirelessly transmits the RF signals (e.g., via an antenna). In some examples, the radio subsystem in the example modem 112 wirelessly receives radio frequency signals (e.g., through an antenna), down-converts the radio frequency signals to baseband signals, and sends the baseband signals to the baseband subsystem. The signals exchanged between the radio subsystem and the baseband subsystem may be digital signals or analog signals. In some examples, the baseband subsystem includes conversion circuitry (e.g., digital-to-analog converters, analog-to-digital converters) and exchanges analog signals with the radio subsystem. In some examples, the radio subsystem includes conversion circuitry (e.g., digital-to-analog converters, analog-to-digital converters) and exchanges digital signals with the baseband subsystem.

In some cases, the baseband subsystem of the example modem 112 may communicate wireless network traffic (e.g., data packets) in a wireless communication network via the radio subsystem on one or more network traffic channels. The baseband subsystem of modem 112 may also send or receive (or both) signals (e.g., motion detection signals or motion detection signals) over the dedicated wireless communication channel through the radio subsystem. In some instances, the baseband subsystem, for example, generates motion detection signals for transmission to detect the space used for motion. In some implementations, the motion-sounding signal includes standard signaling or communication frames that include standard pilot signals used in channel sounding (e.g., channel sounding for beamforming according to the IEEE802.11ac-2013 standard, which is incorporated herein by reference). In some cases, the motion detection signal includes a reference signal known to all devices in the network. In some instances, the baseband subsystem processes received motion detection signals (based on signals that transmit motion detection signals through the space), for example, to detect motion of objects in the space. For example, the baseband subsystem may analyze aspects of a standard signaling protocol (e.g., channel sounding for beamforming in accordance with the ieee802.11ac-2013 standard (such as based on generated steering or other matrices, etc.) to detect channel variations as a result of motion in space.

The example processor 114 may, for example, execute instructions to generate output data based on data inputs. The instructions may include programs, code, scripts, or other types of data stored in memory. Additionally or alternatively, the instructions may be encoded as pre-programmed or re-programmable logic circuits, logic gates, or other types of hardware or firmware components. The processor 114 may be or include a general purpose microprocessor, as a special purpose coprocessor or other type of data processing device. In some cases, the processor 114 performs high-level operations for the wireless communication device 102C. For example, the processor 114 may be configured to execute or interpret software, scripts, programs, functions, executable instructions, or other instructions stored in the memory 116. In some implementations, the processor 114 may be included in the modem 112.

The example memory 116 may include computer-readable storage media, such as volatile memory devices, non-volatile memory devices, or both. The memory 116 may include one or more read only memory devices, random access memory devices, cache memory devices, or a combination of these and other types of memory devices. In some examples, one or more components of the memory may be integrated or otherwise associated with other components of wireless communication device 102C. The memory 116 may store instructions executable by the processor 114. For example, the instructions may include instructions for analyzing channel state information, beamforming steering matrix state information, or other information based on bi-directional channel sounding, such as by one or more operations in the exemplary process 600 of fig. 6, to detect motion of an object in space.

The exemplary power supply unit 118 provides power to the other components of the wireless communication device 102C. For example, other components may operate based on power provided by the power supply unit 118 through a voltage bus or other connection. In some implementations, the power supply unit 118 includes a battery or a battery system, such as a rechargeable battery. In some implementations, the power supply unit 118 includes an adapter (e.g., an AC adapter) that receives an external power signal (from an external source) and converts the external power signal to an internal power signal that is conditioned for components of the wireless communication device 102C. The power supply unit 118 may include other components or operate in other manners.

In the example shown in fig. 1, the wireless communication devices 102A, 102B transmit wireless signals (e.g., according to a wireless network standard, a motion detection protocol, or otherwise). For example, the wireless communication devices 102A, 102B may broadcast wireless motion detection signals (e.g., as described above), or the wireless communication devices 102A, 102B may transmit wireless signals addressed to other devices (e.g., user equipment, client devices, servers, etc.), and the other devices (not shown) as well as the wireless communication device 102C may receive the wireless signals transmitted by the wireless communication devices 102A, 102B. In some cases, the wireless signals transmitted by the wireless communication devices 102A, 102B are repeated periodically, such as according to a wireless communication standard or otherwise.

In the example shown, the wireless communication device 102C processes wireless signals from the wireless communication devices 102A, 102B to detect motion of an object in the space to which the wireless signals access, to determine the location of the detected motion, or both. For example, the wireless communication device 102C may perform one or more of the following exemplary processes described with respect to FIGS. 3-4, or other types of processes for detecting motion or determining a location of detected motion. The space to which the wireless signal is accessed may be an indoor or outdoor space, which may include, for example, one or more areas that are fully or partially enclosed, open areas that are not enclosed, and the like. The space may be or may include the interior of a room, a plurality of rooms or buildings, etc. In some cases, for example, the wireless communication system 100 may be modified such that the wireless communication device 102C may transmit wireless signals, and the wireless communication devices 102A, 102B may process the wireless signals from the wireless communication device 102C to detect motion or determine the location of the detected motion.

The wireless signals used for motion detection may include, for example, beacon signals (e.g., bluetooth beacons, Wi-Fi beacons, other wireless beacon signals), pilot signals (e.g., pilot signals used for channel sounding, such as pilot signals used in beamforming applications) or other standard signals generated for other purposes according to wireless network standards, or non-standard signals generated for motion detection or other purposes (e.g., random signals, reference signals, etc.). In some examples, the wireless signal propagates through an object (e.g., a wall) before or after interacting with the moving object, which may enable detection of movement of the moving object without an optical line of sight between the moving object and the transmitting or receiving hardware. Based on the received signal, the third wireless communication device 102C may generate motion detection data. In some instances, the third wireless communication device 102C may communicate the motion detection data to other devices or systems (such as security systems, etc.), which may include a control center for monitoring movement within a space such as a room, building, outdoor area, etc.

In some implementations, the wireless communication devices 102A, 102B may be modified to transmit motion-sounding signals on separate wireless communication channels (e.g., frequency channels or code channels) in accordance with wireless network traffic signals (e.g., as described above). For example, the third wireless communication device 102C may know the modulation applied to the payload of the motion detection signal and the type or data structure of the data in the payload, which may reduce the amount of processing by the third wireless communication device 102C for motion sensing. The header may include, for example, additional information such as an indication of whether motion was detected by other devices in the communication system 100, an indication of the type of modulation, an identification of the device sending the signal, and so forth.

In the example shown in fig. 1, the wireless communication system 100 is a wireless mesh network having wireless communication links between respective wireless communication devices 102. In the example shown, the wireless communication link between the third wireless communication device 102C and the first wireless communication device 102A may be used to probe the first motion detection field 110A, the wireless communication link between the third wireless communication device 102C and the second wireless communication device 102B may be used to probe the second motion detection field 110B, and the wireless communication link between the first wireless communication device 102A and the second wireless communication device 102B may be used to probe the third motion detection field 110C. In some examples, each wireless communication device 102 detects motion in the motion detection field 110 by processing received signals based on wireless signals transmitted by the wireless communication device 102 through the motion detection field 110 to which the device is attached. For example, as the person 106 shown in fig. 1 moves through the first and third motion detection fields 110A, 110C, the wireless communication device 102 may detect motion from signals it receives based on wireless signals transmitted through the respective motion detection fields 110. For example, a first wireless communication device 102A may detect motion of a person in the two motion detection fields 110A, 110C, a second wireless communication device 102B may detect motion of the person 106 in the motion detection field 110C, and a third wireless communication device 102C may detect motion of the person 106 in the motion detection field 110A.

In some examples, the motion detection field 110 may include, for example, air, solid materials, liquids, or other media through which wireless electromagnetic signals may propagate. In the example shown in fig. 1, the first motion detection field 110A provides a wireless communication channel between the first wireless communication device 102A and the third wireless communication device 102C, the second motion detection field 110B provides a wireless communication channel between the second wireless communication device 102B and the third wireless communication device 102C, and the third motion detection field 110C provides a wireless communication channel between the first wireless communication device 102A and the second wireless communication device 102B. In some aspects of operation, movement of objects in a space is detected using wireless signals transmitted over a wireless communication channel (separate from or shared with a wireless communication channel used by network traffic). The objects may be any type of static or movable object, and may be animate or inanimate. For example, the object may be a human (e.g., human 106 shown in fig. 1), an animal, an inorganic object, or other apparatus, device, or assembly, an object (e.g., a wall, door, window, etc.) that defines all or part of a boundary of a space, or other type of object. In some implementations, motion information from the wireless communication device may be analyzed to determine a location of the detected motion. For example, as described further below, one of the wireless communication devices 102 (or other device communicatively coupled to the device 102) may determine that the detected motion is in the vicinity of the particular wireless communication device. In some examples, the wireless communication device 102 may perform bidirectional channel sounding as described below to detect motion of the object 106.

Fig. 2A and 2B are diagrams illustrating exemplary 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 other types of wireless communication devices. The example wireless communication devices 204A, 204B, 204C transmit wireless signals through the space 200. The exemplary space 200 may be completely or partially closed or open at one or more boundaries of the space 200. The space 200 may be or may include an interior of a room, a plurality of rooms, a building, an indoor area or an outdoor area, and so forth. In the example shown, the first, second, and third walls 202A, 202B, 202C at least partially enclose the space 200.

In the example shown in fig. 2A and 2B, the first wireless communication device 204A is operable to repeatedly (e.g., periodically, intermittently, at predetermined, non-predetermined, or random intervals, etc.) transmit wireless motion probing signals. The second wireless communication device 204B and the third wireless communication device 204C are operable to receive signals based on the motion detection signals transmitted by the wireless communication device 204A. The motion detection signal may be formatted as described above. For example, in some implementations, the motion detection signals include standard signaling or communication frames including standard pilot signals used in channel sounding (e.g., channel sounding for beamforming according to the IEEE802.11ac-2013 standard, which is incorporated herein by reference). The wireless communication devices 204B, 204C each have a modem, processor, or other component configured to process the received motion detection signals to detect motion of objects in the space 200.

As shown, the object is in a first position 214A in fig. 2A, and the object has moved to a second position 214B in fig. 2B. In fig. 2A and 2B, the moving object in the space 200 is represented as a person, but the moving object may be other types of objects. For example, the moving object may be an animal, an inorganic object (e.g., a system, apparatus, device, or assembly), an object used to define all or part of a boundary of the space 200 (e.g., a wall, door, window, etc.), or other type of object.

As shown in fig. 2A and 2B, a plurality of exemplary paths of wireless signals transmitted from the first wireless communication device 204A are shown with dashed lines. Along the first signal path 216, wireless signals are transmitted from the first wireless communication device 204A and reflected by the first wall 202A toward the second wireless communication device 204B. Along the second signal path 218, wireless signals are transmitted from the first wireless communication device 204A and reflected by the second wall 202B and the first wall 202A toward the third wireless communication device 204C. Along the third signal path 220, the wireless signal is transmitted from the first wireless communication device 204A and reflected by the second wall 202B toward the third wireless communication device 204C. Along a fourth signal path 222, wireless signals are transmitted from the first wireless communication device 204A and reflected by the third wall 202C toward the second wireless communication device 204B.

In fig. 2A, along a fifth signal path 224A, a wireless signal is transmitted from the first wireless communication device 204A and reflected by an object at the first location 214A toward the third wireless communication device 204C. Between fig. 2A and 2B, the surface of the object moves from a first position 214A to a second position 214B in the space 200 (e.g., a distance away from the first position 214A). In fig. 2B, along a sixth signal path 224B, the wireless signal is transmitted from the first wireless communication device 204A and reflected by the object at the second location 214B toward the third wireless communication device 204C. As the object moves from the first position 214A to the second position 214B, the sixth signal path 224B depicted in fig. 2B is longer than the fifth signal path 224A depicted in fig. 2A. In some examples, signal paths may be added, removed, or otherwise modified due to movement of objects in space.

The exemplary wireless signals shown in fig. 2A and 2B may undergo attenuation, frequency shift, phase shift, or other effects through their respective paths and may have portions that propagate in other directions, e.g., through walls 202A, 202B, and 202C. In some examples, the wireless signal is a Radio Frequency (RF) signal. The wireless signals may include other types of signals.

In the example shown in fig. 2A and 2B, the first wireless communication apparatus 204A may repeatedly transmit wireless signals. In particular, fig. 2A shows a wireless signal being transmitted from a first wireless communication device 204A at a first time, and fig. 2B shows the same wireless signal being transmitted from the first wireless communication device 204A at a second, later time. The transmission signal may be transmitted continuously, periodically, at random or intermittent times, etc., or by a combination thereof. The transmit signal may have multiple frequency components in a frequency bandwidth. The transmission signal may be transmitted from the first wireless communication device 204A in an omnidirectional manner, in a directional manner, or in other manners. In the example shown, the wireless signals traverse multiple respective paths in space 200, and the signals along each path may become attenuated due to path loss, scattering, or reflection, etc., and may have a phase or frequency offset.

As shown in fig. 2A and 2B, the signals from the 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 a received signal. Due to the effect of multiple paths in space 200 on the transmit signal, space 200 may be represented as a transfer function (e.g., a filter) that inputs the transmit signal and outputs the receive signal. As an object moves in space 200, the attenuation or phase shift affecting the signal in the signal path may change and thus the transfer function of space 200 may change. In the case where it is assumed that the same wireless signal is transmitted from the first wireless communication apparatus 204A, if the transfer function of the space 200 is changed, the output of the transfer function (i.e., the reception signal) will also be changed. The change in the received signal can be used to detect movement of the object.

Mathematically, the transmission signal f (t) transmitted from the first wireless communication apparatus 204A can be described according to equation (1):

wherein, ω is_nRepresenting the frequency of the nth frequency component of the transmitted signal, c_nA complex coefficient representing the nth frequency component, and t represents time. When the transmission signal f (t) is transmitted from the first wireless communication apparatus 204A, the output signal r from the path k can be described by equation (2)_k(t)：

Wherein, α_n,kRepresenting the attenuation factor (or channel response; e.g., due to scattering, reflection, and path loss) for the nth frequency component along path k, and_n,krepresenting the phase of the signal for the nth frequency component along path k. The received signal R at the wireless communication device can then be described as all output signals R from all paths to the wireless communication device_k(t) sum ofFormula (3):

substituting formula (2) for formula (3) to obtain formula (4):

the received signal R at the wireless communication device may then be analyzed. The received signal R at the wireless communication device may be transformed to the frequency domain, for example, using a Fast Fourier Transform (FFT) or other type of algorithm. The transformed signal may represent the received signal R as a series of n complex values, where (n frequencies ω_nOf) each corresponding one of the frequency components corresponds to a complex value. For frequency omega_nFrequency component of (2), complex value H_nCan be represented by the following formula (5):

for a given frequency component ω_nComplex value of (H)_nIndicating the frequency component omega_nThe relative magnitude and phase offset of the received signal. Complex value H when an object moves in space_nChannel response α due to space_n,kIs changed. Thus, a detected change in channel response may be indicative of movement of an object within the communication channel. In some instances, noise, interference, or other phenomena may affect the channel response detected by the receiver, and the motion detection system may reduce or isolate such effects to improve the accuracy and quality of the motion detection capability. In some implementations, the overall channel response may be expressed as:

in some instances, the channel response h for the space may be determined, for example, based on mathematical estimation theory_ch. For example, canUsing candidate channel response (h)_ch) To modify the reference signal R_efThe maximum likelihood method can then be used to select the given and received signal (R)_cvd) The best matching candidate channel. In some cases, from the reference signal (R)_ef) And candidate channel response (h)_ch) Obtaining an estimated received signalThen changes the channel response (h)_ch) So as to estimate the received signalThe squared error of (c) is minimized. This may be done, for example, with optimization criteria

Shown mathematically as:

the minimization or optimization process may utilize adaptive filtering techniques such as least mean square (L MS), recursive least squares (R L S), batch least squares (B L S), etc. the channel response may be a Finite Impulse Response (FIR) filter or an Infinite Impulse Response (IIR) filter, etc. As shown in the above equation, the received signal may be considered as a convolution of the reference signal and the channel response.

Fig. 3A and 3B are diagrams of an exemplary motion detection system 300. The exemplary motion detection system 300 includes a transmitter 302 and a receiver 304, the transmitter 302 and the receiver 304 communicating with each other via a wireless signal 306. The transmitter 302 and receiver 304 may be implemented similarly to the wireless communication device 102 of fig. 1. As shown, the wireless signal 306 travels through space in a number of different directions, being reflected by walls or other physical boundaries. Thus, the wireless signals 306 each arrive at the receiver 306 at a different time, as shown in the time domain plot 312. The time domain plot 312 may be used to calculate or otherwise obtain channel state information, such as channel response, beamforming state information, beamforming steering matrix state information, or other information representing an effective transfer function of the space.

In the example shown, an object moving close to transmitter 302 (as shown in FIG. 3A) intersects a larger surface of a wireless RF signal represented as a three-dimensional sphere that transmits RF energy because the larger the contact surface between the RF signal and the moving object, the larger solid angle (α)310 between transmitter 302 and moving object 308. As a result, the larger the solid angle (α)310 between the object 302 and the moving object may be, as compared to the same sized object moving at a greater distance from transmitter 302 (as shown in FIG. 3B), the moving object reflects more RF energy in different directions.

Fig. 4A and 4B are diagrams of an exemplary motion detection system 400 based on bi-directional channel sounding. The exemplary motion detection system 400 includes a pairing of wireless devices 402 in communication with each other. The wireless device 402 may be implemented similarly to the wireless communication device 102 of fig. 1. Wireless devices 402 may communicate with each other using Radio Frequency (RF) signals (e.g., signals formatted according to the 802.11 standard) or other types of wireless signals. In the example shown, wireless device 402A transmits signal 404A for channel sounding in one direction, and wireless device 402B transmits signal 404B for channel sounding in the opposite direction. Based on the transmitted signal 404, each wireless device 402 may determine channel state information for the space traversed by the signal 404. In some cases, signal 404B is transmitted after (e.g., sequentially) signal 404A. Device 402 may send the determined channel state information (e.g., channel response) to a designated device as described above, which may analyze the channel state information from both devices 402 to detect motion of object 406 (dog 406A and person 406B). Although described below with respect to analyzing channel state information, beamforming steering matrix state information, or other information representing an effective transfer function of a space may be analyzed in addition to or in place of channel state information.

In the example shown, in both scenarios of fig. 4A, 4B, the unidirectional channel sounding technique may provide similar motion conclusions, since object 406 produces a similar solid angle for wireless device 402A. For example, in the example shown, when dog 406A (shown in fig. 4A) moves in the vicinity of wireless device 402A, it causes very much interference to signal 404A, which may be similar to the interference caused by a larger person 406B (shown in fig. 4B) that is further away from wireless device 402A, resulting in a similar solid angle. The solid angles may be similar in the case where the difference between the solid angles generated by wireless devices 402A and 402A is below a certain threshold (e.g., within 0-10 degrees of difference). In some cases, the threshold may be other values representing an angular difference greater than a 10 degree difference. In some cases, channel variations associated with the wireless devices 402A, 402B may be indicated by measurements outside the solid angle. In this case, the channel variation associated with wireless device 402A may be similar to the channel variation associated with wireless device 402B if the channel variation associated with wireless device 402A is within the threshold of the channel variation associated with wireless device 402B. Thus, with unidirectional channel sounding, it may be determined that there is motion of a large object (e.g., a person) in the space traversed by signal 404A in both scenarios, which may or may not be accurate. However, by using bi-directional channel sounding, the category of motion can be determined (e.g., whether an object in space is a large (human) object or a small (dog) object). Additionally, the relative position of the detected motion may be determined.

For example, in the example shown in fig. 4A, channel state information may be obtained based on the two signals 404A, 404B. The channel state information determined at wireless device 402A (based on signal 404B) may show relatively small channel disturbances due to a relatively small object moving in space (dog 406A), while the channel state information determined at wireless device 402B (based on signal 404A) may show relatively large channel disturbances. The two sets of channel state information may be compared or otherwise analyzed to determine that the moving object is a small object and that the small object is moving closer to device 402A than to device 402B.

Similarly, in the example shown in fig. 4B, the channel state information determined at wireless device 402A (based on signal 404B) may show relatively large channel disturbances due to the relatively large object moving in space (person 406B) (and close to the source of signal 404B), while the channel state information determined at wireless device 402B (based on signal 404A) may show more moderate channel disturbances. The two sets of channel state information may be compared or otherwise analyzed to determine that the moving object is a larger object and that the object is moving closer to the device 402B than to the device 402A.

In some implementations, bi-directional channel sounding may be performed between multiple devices in a wireless communication network. For example, referring to the example shown in fig. 1, bi-directional channel sounding may be performed between wireless communication devices 102A, 102B, between wireless communication devices 102A, 102C, and between wireless communication devices 102B, 102C. Channel state information may be determined based on the bi-directional analysis described above for each respective pair of devices 102, and the set of channel state information may be analyzed to determine that object 106 is within first motion detection field 110A and relatively equidistant between devices 102A, 102C.

Fig. 5A and 5B are diagrams illustrating an exemplary motion-localized area 502 in a motion detection system 500. In the example shown, the motion detection system 500 includes a wireless communication device 502, and the wireless communication device 502 may be implemented similarly to the wireless communication device 102 of fig. 1. The system 500 may operate similarly to the system 400 of fig. 4A-4B (e.g., motion of an object in space may be detected based on bi-directional channel sounding). In the example shown, the wireless communication device 502 iterates the roles of the transmitter and receiver between changing roles at a minimum interval (e.g., milliseconds apart) to capture a very similar physical environment.

In the exemplary system 500A of fig. 5A, the system 500A may determine that an object is moving in the motion detection region 508 ("proximity sensor 2") if the wireless communication device 502A (in receiver mode) reports a greater strength of detected wireless channel variation over time than the same report from the wireless communication device 502B (in receiver mode). Likewise, the system 500A may determine that an object is moving in the motion detection region 504 ("near sensor 1") if the wireless communication device 502B (in receiver mode) reports a greater strength of detected wireless channel variation over time than the same report from the wireless communication device 502A (in receiver mode). If the two wireless communication devices 502 report similar amounts of channel change over time, the system 500A may determine that the object is moving in the motion detection region 506 ("middle region").

The exemplary system 500B shown in fig. 5B is the same as the exemplary system 500A shown in fig. 5A, except that it has three wireless communication devices 502. With more wireless communication devices 502, the system 500B of fig. 5B includes more motion detection areas than the system 500A. For example, system 500A includes three motion detection regions 504, 506, 508, while system 500B includes nine motion detection regions 510, 512, 514, 516, 518, 520, 522, 524, 526. In the example shown, system 500B may determine, based on bi-directional channel sounding, that object 530 is moving within the intersection of motion detection region 514 ("middle region of sensors 1 and 3") and motion detection region 516 ("middle region of sensors 1 and 2").

Fig. 6 is a flow diagram illustrating an exemplary process 600 for detecting motion of an object in space based on bi-directional channel sounding. The operations of process 600 may be performed by one or more processors of a device coupled to a wireless network serving a space. For example, operations in the example process 600 may be performed by the processor subsystem 114 of the example wireless communication device 102 of fig. 1 to analyze channel state information, beamforming steering matrix state information, or other information representing an effective transfer function of a space based on bi-directional channel sounding between two devices 102 and detect whether motion has occurred in the space. The exemplary process 600 may be performed by other types of devices. The exemplary process 600 may include additional or different operations, and these operations may be performed in the order shown or in other orders. In some cases, one or more of the operations illustrated in fig. 6 are implemented as a process comprising multiple operations, sub-processes, or other types of routines. In some cases, the operations may be combined, performed in other orders, performed in parallel, iterated or otherwise repeated, or performed in other ways.

In the example process 600, operations 602A, 604A, and 606A may be performed by a first wireless communication device, while operations 602B, 604B, and 606B may be performed by a second wireless communication device. For example, referring to the example shown in fig. 4A-4B, operations 602A, 604A, and 606A may be performed by wireless device 402A, while operations 602B, 604B, and 606B may be performed by wireless device 402B. As another example, operations 602A, 604A, and 606A may be performed by wireless communication device 502A of fig. 5A, while operations 602B, 604B, and 606B may be performed by wireless communication device 502B of fig. 5A.

At 602, wireless signals are transmitted through a space between wireless communication devices. For example, referring to the examples shown in fig. 4A-4B, wireless signals 404A, 404B are transmitted by wireless devices 402A, 402B, respectively. The wireless signals may be Radio Frequency (RF) signals and may include reference signals or beacon signals for determining whether motion has occurred in the space. In some cases, the wireless signals are formatted according to a standard (e.g., the 802.11Wi-Fi standard). The wireless signals may be formatted in other ways. In some implementations, signals are transmitted bi-directionally between the wireless devices 402A, 402B. In some cases, the first set of wireless signals is transmitted in a first direction from the first wireless communication device 402A to the second wireless communication device 402B, and the second set of wireless signals is transmitted in a second direction from the second wireless communication device 402B to the first wireless communication device 402A.

At 604, a signal transmitted by another apparatus at 602 is received, and at 606, the received signal is analyzed to obtain channel information. In an example, a first set of channel information may be received from a first wireless communication apparatus 402A and a second set of channel information may be received from a second wireless communication apparatus 402B. In some implementations, the channel information includes CSI (e.g., channel response), and the analysis may be based on mathematical estimation theory as described above. In some implementations, the channel information includes beamforming state information or beamforming steering matrix information. The channel information may include other information representing the effective transfer function of the space.

At 608, the set of channel information obtained at 606A, 606B is analyzed to detect whether an object is moving in the space traversed by the wireless signal. The analysis at 608 may be performed by any device communicatively coupled to the wireless device for transmission/reception. In some implementations, the analysis is performed by one of the devices (e.g., where the device is designated as a hub device). In some implementations, the analysis is performed by a remote server communicatively coupled to the wireless device (e.g., in the cloud). In some implementations, an action or programmed response may be taken after motion is detected. For example, a computing device (e.g., the device that analyzes at 608) may activate a security alert (e.g., send an alert to security personnel, the house owner's mobile phone, or other device), activate lighting or HVAC at the location where motion is detected (e.g., in a room, hallway, or outdoors), or perform a combination of these or other types of programmed responses.

In some implementations, a category of motion may be detected at 608. For example, it may be determined whether the moving object is relatively large (e.g., a person) or relatively small (e.g., a dog or cat). Additionally, in some implementations, the relative position of the detected motion may be determined. For example, the detected motion may be localized to a motion detection region, as described above with respect to fig. 5A-5B. In some cases, the category or relative location of motion may be determined based on a comparison of the respective sets of channel information or based on other analysis of the sets of channel information. In an example, as shown in fig. 5A, in a case where the first channel information set indicates more channel variation with the passage of time than the second channel information set, it may be determined that the object is moving in the area near the first wireless communication apparatus 402A, and in a case where the second channel information set indicates more channel variation with the passage of time than the first channel information set, it may be determined that the object is moving in the area near the second wireless communication apparatus 402B. In another example, as illustrated in fig. 5B, in a case where the first channel information set indicates similar channel variations with the passage of time as compared to the second channel information set, it may be determined that the object is moving in the area between the first wireless communication apparatus 402A and the second wireless communication apparatus 402B.

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-readable storage medium for execution by, or to control the operation of, data processing apparatus. The computer readable storage medium may be or 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. Further, although the computer-readable storage medium is not a propagated signal, the computer-readable storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer-readable storage medium may also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices). The computer-readable storage medium may include a plurality of computer-readable storage devices. The computer-readable storage devices may be co-located (with the instructions stored in a single storage device) or located in different locations (e.g., with the instructions stored in distributed locations).

Some of the operations described in this specification may be implemented as operations by a data processing apparatus on data stored in a memory (e.g., on one or more computer-readable storage devices) or received from other sources. 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. An apparatus can comprise special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). The apparatus can 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. In some examples, a data processing apparatus includes a set of processors. The set of processors may be co-located (e.g., multiple processors in the same computing device) or in different locations from one another (e.g., multiple processors in a distributed computing device). The memory for storing data executed by the data processing apparatus may be co-located with the data processing apparatus (e.g., the computing device executing instructions stored in the memory of the same computing device) or located in a different location than the data processing apparatus (e.g., the client device executing instructions stored on the server device).

A computer program (also known as a program, 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. The 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 file) 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).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and the processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include a processor for acting in accordance with instructions and one or more memory devices for storing instructions and data. A computer can also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., a non-magnetic drive (e.g., a solid state drive), a magnetic disk, a magneto-optical disk, or an optical disk. However, the computer need not have such a device. Further, the computer may be embedded in other devices, such as a phone, a tablet, an appliance, a mobile audio or video player, a game player, a Global Positioning System (GPS) receiver, an internet of things (IoT) device, a machine-to-machine (M2M) sensor or actuator, or a portable storage device (e.g., a Universal Serial Bus (USB) flash drive). Suitable means for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices (e.g., EPROM, EEPROM, flash memory devices, etc.), magnetic disks (e.g., internal hard disk, removable disk, etc.), magneto-optical disks, and CD-ROM and DVD-ROM disks. In some cases, the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, the operations may be implemented on a computer having a display device (e.g., a monitor or other type of display device) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse, trackball, stylus, touch-sensitive screen, or other type of pointing device) by which the user may provide input to the computer. Other kinds of devices may also be used to provide for interaction with the user; for example, feedback provided to the user can be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, the computer may interact with the user by sending and receiving documents with respect to the device used by the user (e.g., by sending web pages to a web browser in response to requests received from the web browser on the user's client device).

A communication network may include one or more of a local area network ("L AN") and a wide area network ("WAN"), the Internet (e.g., the Internet), a network including satellite links, and a peer-to-peer network (e.g., AN ad hoc peer-to-peer network).

In a general aspect of the examples described herein, motion is detected based on bi-directional channel sounding.

In a first example, a first set of channel information from a first apparatus is obtained. The first set of channel information is a first set of wireless signals transmitted through space from a second apparatus based on a first time in a certain time frame. A second set of channel information is obtained from a second apparatus. The second set of channel information is a second set of wireless signals transmitted through the space from the first apparatus based on a second time in the time frame. The first set of channel information and the second set of channel information are analyzed to detect a category of motion or a location of the detected motion in space during the time frame.

Implementations of the first example may include one or more of the following features. The first set of channel information and the second set of channel information are based on wireless signals transmitted bi-directionally through the space between the first device and the second device. The wireless signals include reference signals or beacon signals. The first set of wireless signals is transmitted from the first apparatus to the second apparatus in a first direction, and the second set of wireless signals is transmitted from the second apparatus to the first apparatus in a second direction. The first set of channel information is compared to the second set of channel information to determine whether the object is moving in an area proximate to the first device or the second device.

Implementations of the first example may include one or more of the following features. Determining that the object is moving in an area near the first apparatus if the first set of channel information indicates more channel variation over time than the second set of channel information; or in the case where the second channel information set indicates more channel variation with the passage of time than the first channel information set, it is determined that the object is moving in the area near the second apparatus. In a case where the first channel information set indicates similar channel variations with the passage of time as compared with the second channel information set, it is determined that the object is moving in the area between the first device and the second device. A category of motion is determined. The type of the moving object is identified. Determining that the small object is moving closer to the first apparatus than to the second apparatus if the first set of channel information indicates less channel disturbances over time than the second set of channel disturbances; or in the case where the first set of channel information indicates greater channel disturbances over time than the second set of channel disturbances, determining that the large object is moving closer to the second apparatus than to the first apparatus.

In some implementations, a computing system (e.g., a wireless communication device, a computer system, or other type of system communicatively coupled to a wireless communication device) includes a data processing apparatus and a memory storing instructions operable, when executed by the data processing apparatus, to perform one or more operations of the first example. In some implementations, the motion detection apparatus includes one or more processors and memory including instructions that, when executed by the one or more processors, cause the motion detection apparatus to perform one or more operations of the first example. In some implementations, the computer-readable medium stores instructions operable, when executed by the data processing apparatus, to perform one or more of the operations of the first example.

While this specification contains many specifics, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features specific to particular examples. Certain features that are described in this specification in the context of separate implementations can also be combined. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple embodiments separately or in any suitable subcombination.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other embodiments are within the scope of the following claims.