Radio Frequency Sensing Using a Single Device Based on Simultaneous Transmission and Reception

Abstract

Techniques are provided for radio frequency (RF) sensing using a single wireless device. An exemplary method for determining a distance to an object using radio frequency sensing includes transmitting a radio frequency signal using a transmit channel on the wireless device, receiving a leakage signal using a receive channel on the wireless device at a first time such that the leakage signal is based on the radio frequency signal, receiving a reflected signal using a receive channel on the wireless device at a second time such that the reflected signal is based on the radio frequency signal reflecting from the object, and determining a distance to the object based at least in part on a difference between the first time and the second time.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. patent application Ser. No. 17 / 242,589, entitled “RADIO FREQUENCY SENSING USING A SINGLE DEVICE BASED ON CONCURRENT TRANSMIT AND RECEIVE,” filed April 28, 2021, which is assigned to the assignee of the present application and is expressly incorporated by reference in its entirety herein. [Background technology]

[0002] A wireless local area network (WLAN) may be formed by one or more access points (APs) that provide a shared wireless medium for use by several client devices. Each AP, which may correspond to a basic service set (BSS), periodically broadcasts a beacon frame to enable compatible client devices within wireless range of the AP to establish and maintain a communication link with the WLAN. WLANs that operate according to the IEEE 802.11 family of standards are commonly referred to as Wi-Fi networks, and client devices that communicate with APs in a Wi-Fi network may be referred to as wireless stations (STAs).

[0003] Some wireless devices may be configured to communicate with other wireless devices using radio frequency signals. For example, a network may include several Internet of Things (IoT) objects and devices configured to wirelessly communicate with each other. Many IoT devices, such as smart appliances, smart TVs, and smart thermostats, may be configured to support wireless protocols such as Wi-Fi and / or Bluetooth. The wireless channel between the wireless device and the AP may be used for radio frequency (RF) sensing applications. The devices may listen and capture channel parameters for transmissions between the devices. Objects may be detected based on changes in channel conditions between the wireless devices. Summary of the Invention [Means for solving the problem]

[0004] An exemplary method for determining a distance to an object using radio frequency sensing according to the present disclosure includes transmitting a radio frequency signal using a transmit channel on the wireless device; receiving the leakage signal using a receive channel on the wireless device at a first time, such that the leakage signal is based on the radio frequency signal; receiving a reflected signal using a receive channel on the wireless device at a second time, such that the reflected signal is based on the radio frequency signal reflecting from the object; and determining a distance to the object based at least in part on a difference between the first time and the second time.

[0005] Implementations of such methods may include one or more of the following features: The radio frequency signal may be a pre-designated sequence. The pre-designated sequence may be a single carrier Zadoff-Chu sequence. The pre-designated sequence may include orthogonal frequency division multiplexing symbols. The pre-designated sequence may include one or more Wi-Fi packets. A plurality of radio frequency signals may be transmitted and receiving one or more of the plurality of radio frequency signals. The method may include transmitting a plurality of radio frequency signals using a plurality of transmission channels. Receiving the radio frequency signals may include receiving the radio frequency signals using a plurality of receive chains. Angle of arrival and angle of departure of the received and transmitted radio frequency signals may be determined. The steps of transmitting the radio frequency signal and receiving the radio frequency signal may be performed using a single chain transmit and receive operation.

[0006] An example apparatus according to the present disclosure includes a memory, at least one transceiver including at least one transmit chain and at least one receive chain, and at least one processor communicatively coupled to the memory and the at least one transceiver, where the at least one processor is configured to: transmit a radio frequency signal using the at least one transmit chain; receive a leakage signal using the at least one receive chain at a first time such that the leakage signal is based on the radio frequency signal; receive a reflected signal using the at least one receive chain at a second time such that the reflected signal is based on the radio frequency signal reflecting from the object; and determine a distance to the object based at least in part on a difference between the first time and the second time.

[0007] Implementations of such an apparatus may include one or more of the following features: The radio frequency signal may be a pre-designated sequence. The pre-designated sequence may be a single carrier Zadoff-Chu sequence, may include orthogonal frequency division multiplexing symbols, and / or may include one or more Wi-Fi packets. The at least one processor may be further configured to transmit the multiple radio frequency signals and receive one or more of the multiple radio frequency signals. The at least one processor may be further configured to transmit the multiple radio frequency signals using multiple transmit chains. The at least one processor may be further configured to receive the radio frequency signals using multiple receive chains. The at least one processor may be further configured to determine an angle of arrival of the received radio frequency signals. The at least one processor may be further configured to determine an angle of departure of the radio frequency signals. The at least one processor may be configured to transmit the radio frequency signals and receive the radio frequency signals using single chain transmit and receive operations.

[0008] An exemplary apparatus for determining a distance to an object using radio frequency sensing according to the present disclosure includes means for transmitting a radio frequency signal using a transmit channel on the wireless device, means for receiving a leakage signal using a receive channel on the wireless device at a first time such that the leakage signal is based on the radio frequency signal, means for receiving a reflected signal using a receive channel on the wireless device at a second time such that the reflected signal is based on the radio frequency signal reflecting from the object, and means for determining a distance to the object based at least in part on a difference between the first time and the second time.

[0009] A non-transitory processor-readable storage medium including processor-readable instructions that cause one or more processors to determine a distance to an object using radio frequency sensing according to the present disclosure includes code for transmitting a radio frequency signal using a transmit channel on the wireless device, code for receiving a leakage signal using a receive channel on the wireless device at a first time, such that the leakage signal is based on the radio frequency signal, code for receiving a reflected signal using a receive channel on the wireless device at a second time, such that the reflected signal is based on the radio frequency signal reflecting from the object, and code for determining a distance to the object based at least in part on a difference between the first time and the second time.

[0010] An exemplary method for determining a distance to an object using radio frequency sensing according to the present disclosure includes setting a receive gain on a wireless device to a first level, transmitting a radio frequency signal at a first time at the wireless device such that a leakage signal is received by the wireless device at the first level of receive gain, setting the receive gain on the wireless device to a second level, receiving a reflection of the radio frequency signal at the wireless device at a second time such that the receive gain is at the second level, and determining a distance to the object based at least in part on a difference between the first time and the second time.

[0011] An example apparatus according to the present disclosure includes a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, where the at least one processor is configured to: set a receive gain on a wireless device to a first level; transmit a radio frequency signal at a first time at the wireless device such that a leakage signal is received by the wireless device at the first level of receive gain; set a receive gain on the wireless device to a second level; receive a reflection of the radio frequency signal at the wireless device at a second time such that the receive gain is at the second level; and determine a distance to the object based at least in part on a difference between the first time and the second time.

[0012] An example method for setting a transmit gain for radio frequency sensing according to the present disclosure includes setting a first transmit gain to avoid receiver saturation, transmitting a first signal using the first transmit gain, receiving a reflection of the first signal, and estimating a transmit gain adjustment value, transmitting a second signal using the transmit gain adjustment value, receiving a reflection of the second signal, and estimating the transmit gain adjustment value.

[0013] An exemplary method for controlling a receiver in a wireless device for radio frequency sensing according to the present disclosure includes setting a receive gain on the wireless device to a first level, transmitting a radio frequency signal at the wireless device at a first time, where the leakage signal is received by the wireless device at the first level of receive gain, setting a receive gain on the wireless device to a second level, receiving a reflection of the radio frequency signal at the wireless device at a second time, where the receive gain is at the second level, and determining a distance to an object based at least in part on a difference between the first time and the second time.

[0014] Items and / or techniques described herein may provide one or more of the following capabilities, as well as other capabilities not mentioned: A wireless device is configured to transmit a radio frequency (RF) sensing signal. The gain of one or more receive chains in the wireless device may be increased after the RF sensing signal is transmitted. The RF sensing signal may be reflected by an object and detected by the receive chain. A distance and an orientation to the object may be determined. A single wireless device may be used for indoor mapping. The RF sensing signal may be a WiFi signal. The bandwidth of the RF sensing signal may be varied. User gestures may be detected. Other capabilities may be provided, and not every implementation according to the present disclosure must provide any, much less all, of the described capabilities. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram of an example of a wide local area network (WLAN). [Diagram 2] 1 is a block diagram of components of an example wireless device. [Diagram 3] FIG. 2 is a block diagram of components of an exemplary access point. [Figure 4] FIG. 1 is a conceptual diagram of radio frequency sensing by simultaneous transmission and reception by a wireless device. [Diagram 5] 5 is a graph of an example received signal at the wireless device of FIG. 4. [Figure 6] FIG. 1 is a conceptual diagram of intra-chain transmission and reception by wireless devices. [Figure 7] 1 is an exemplary process flow for a method for setting a transmit gain for radio frequency sensing. [Figure 8] 1 is an exemplary process flow for a method for setting a receiver gain for radio frequency sensing. [Figure 9]1 is an exemplary process flow of a method for controlling a receiver in a wireless device for radio frequency sensing. [Figure 10] 1 is an exemplary process flow for a method for determining distance to an object using radio frequency sensing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Described herein are techniques for RF sensing using a single wireless device. Channel capture techniques and RF sensing have become important features in many wireless networks. For example, some IEEE 802.11ac and 802.11ax compatible Wi-Fi access points support channel capture-based RF sensing, which may have enabled RF sensing applications. However, these conventional solutions have limitations and are not suitable for many applications. In general, conventional channel capture techniques require a second wireless device within range to transmit a wireless signal (e.g., a Wi-Fi packet) so that the first wireless device can listen to the signal and capture the channel. The requirement of two wireless devices precludes the use of RF sensing in scenarios where there is only one wireless device or where there is no wireless traffic to listen to and capture the channel (e.g., in a car or at night when device communication traffic is low). In addition, the second wireless device may have certain transmission behaviors that cause changes in channel capture even when there is no motion, such as switching of transmit chains, random phase between transmit chains, etc., which may degrade RF sensing performance. The use of two devices also presents challenges in determining the exact location of the motion (i.e., determining whether the motion is near the first device or near the second device).

[0017] The techniques provided herein provide an RF sensing system that uses only a single wireless device. The single wireless system can be configured to utilize simultaneous transmission and reception to determine channel capture without requiring another wireless device or additional wireless traffic. Because the techniques use a single wireless device, they reduce or eliminate interoperability issues faced by current channel capture methods of the previous two devices. Furthermore, the use of a single wireless system eliminates ambiguity in determining location. The single wireless device described herein can be used for mapping applications, sensing the presence of a user, detecting user gestures, and other RF sensing applications. These techniques and configurations are examples, and other techniques and configurations may be used.

[0018] The following description provides examples and does not limit the scope, applicability, or examples described in the claims. Changes may be made in the function and arrangement of the elements described without departing from the scope of the present disclosure. Various examples may omit, substitute, or add various procedures or components, as appropriate. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in other examples.

[0019] Referring initially to FIG. 1, a block diagram illustrates an example of a WLAN network 100, such as, for example, a network implementing at least one of the IEEE 802.11 family of standards. The WLAN network 100 may include an access point (AP) 105 and one or more wireless devices 110 or stations (STAs), such as mobile stations, personal digital assistants (PDAs), other handheld devices, netbooks, notebook computers, tablet computers, laptops, display devices (e.g., TVs, computer monitors, etc.), printers, IoT devices, etc. Although only one AP 105 is shown, the WLAN network 100 may have multiple APs 105. Each of the wireless devices 110, which may also be referred to as a mobile station (MS), mobile device, access terminal (AT), user equipment (UE), subscriber station (SS), or subscriber unit, may associate and communicate with the AP 105 via a communication link 115. Each AP 105 has a geographic coverage area 125 such that the wireless devices 110 within that area may typically communicate with the AP 105. The wireless devices 110 may be distributed throughout the geographic coverage area 125. Each wireless device 110 may be fixed or mobile. The principles of the present disclosure are described in the context of wireless systems for purposes of illustration. Nevertheless, it will be understood that these principles are not necessarily limited to wireless systems and may also be implemented in devices and systems configured to communicate via wired connections.

[0020] A wireless device 110 may be covered by more than one AP 105 and may therefore be associated with one or more APs 105 at different times. A single AP 105 and an associated set of stations may be referred to as a Basic Service Set (BSS). An Extended Service Set (ESS) is a set of connected BSSs. A Distribution System (DS) is used to connect APs 105 in an Extended Service Set. A geographic coverage area 125 of an access point 105 may be divided into sectors that make up only a portion of the coverage area. A WLAN network 100 may include access points 105 of different types (e.g., metropolitan area, home network, etc.), with overlapping coverage areas of various sizes and different technologies. In other examples, other wireless devices may communicate with the AP 105.

[0021] The wireless devices 110 may communicate with each other via the AP 105 using the communication links 115, but each wireless device 110 may also communicate directly with one or more other wireless devices 110 via a direct wireless link 120. Two or more wireless devices 110 may communicate via the direct wireless link 120 when both wireless devices 110 are in an AP geographic coverage area 125 or when one or none of the wireless devices 110 are within an AP geographic coverage area 125. Examples of the direct wireless link 120 may include a Wi-Fi direct connection, a Wi-Fi tunneled direct link setup (TDLS) link, a 5G-NR sidelink, a connection established by using PC5, and other P2P group connections. The wireless devices 110 in these examples may communicate according to WLAN radio and baseband protocols, including physical and MAC layers from IEEE 802.11 and its various versions including, but not limited to, 802.11b, 802.11g, 802.11a, 802.11n, 802.11ac, 802.11ad, 802.11ah, 802.11ax, etc. In other implementations, other peer-to-peer connections and / or ad-hoc networks may be implemented within the WLAN network 100.

[0022] 2, UE 200 is an example of a wireless device 110 and comprises a computing platform including a processor 210, a memory 211 including software (SW) 212, one or more sensors 213, a transceiver interface 214 for a transceiver 215, a user interface 216, a satellite positioning system (SPS) receiver 217, a camera 218, and a positioning (motion) device 219. The processor 210, memory 211, sensors 213, transceiver interface 214, user interface 216, SPS receiver 217, camera 218, and positioning (motion) device 219 may be communicatively coupled to each other by a bus 220 (e.g., may be configured for optical and / or electrical communication). One or more of the depicted devices (e.g., one or more of camera 218, positioning (motion) device 219, and / or sensor 213, etc.) may be omitted from UE 200. The processor 210 may include one or more intelligent hardware devices, e.g., a central processing unit (CPU), a microcontroller, an application specific integrated circuit (ASIC), etc. The processor 210 may comprise multiple processors, including a general purpose / application processor 230, a digital signal processor (DSP) 231, a modem processor 232, a video processor 233, and / or a sensor processor 234. One or more of the processors 230-234 may comprise multiple devices (e.g., multiple processors). For example, the sensor processor 234 may comprise, for example, a processor for radio frequency (RF) sensing and ultrasound, etc. The modem processor 232 may support dual SIM / dual connectivity (and even more SIMs). For example, one SIM (Subscriber Identity Module or Subscriber Identity Module) may be used by an original equipment manufacturer (OEM) and another SIM may be used by an end user of the UE 200 for connectivity. The memory 211 is a non-transitory storage medium that may include random access memory (RAM), flash memory, disk memory, and / or read-only memory (ROM), etc.The memory 211 stores the software 212, which may be processor-readable, processor-executable software code including instructions that, when executed, are configured to cause the processor 210 to perform various functions described herein. Alternatively, the software 212 may not be directly executable by the processor 210, but may be configured, for example, when compiled and executed, to cause the processor 210 to perform a function. The description may refer only to the processor 210 performing a function, but includes other implementations, such as the processor 210 executing software and / or firmware. The description may refer to the processor 210 performing a function as a shorthand for one or more of the processors 230-234 performing a function. The description may refer to the UE 200 performing a function as a shorthand for one or more of the appropriate components of the UE 200 performing a function. The processor 210 may include a memory with instructions stored therein in addition to and / or instead of the memory 211. The functionality of processor 210 is discussed more fully below.

[0023] The configuration of UE 200 shown in FIG. 2 is an example of the present invention including the claims, and is not a limitation, and other configurations may be used. For example, an exemplary configuration of a UE includes one or more of processors 230-234 of processor 210, memory 211, and wireless transceiver 240. Other exemplary configurations include processors 230-234 of processor 210, memory 211, one or more of wireless transceiver 240, one or more of sensors 213, user interface 216, SPS receiver 217, camera 218, PMD 219, and / or wired transceiver 250. Other configurations may not include all of the components of UE 200. For example, an IoT device may include one or more wireless transceivers 240, memory 211, and processor 230.

[0024] The UE 200 may include a modem processor 232 that may be capable of performing baseband processing of signals received and downconverted by the transceiver 215 and / or the SPS receiver 217. The modem processor 232 may perform baseband processing of signals to be upconverted for transmission by the transceiver 215. Also or alternatively, the baseband processing may be performed by the processor 230 and / or the DSP 231. However, other configurations may be used to perform the baseband processing.

[0025] The UE 200 may include sensors 213, which may include, for example, an inertial measurement unit (IMU) 270, one or more magnetometers 271, and / or one or more environmental sensors 272. The IMU 270 may comprise one or more inertial sensors, for example, one or more accelerometers 273 (e.g., collectively responsive to acceleration of the UE 200 in three dimensions) and / or one or more gyroscopes 274. The magnetometers may provide measurements for determining an orientation (e.g., relative to magnetic north and / or true north), which may be used for any of a variety of purposes, for example, to support one or more compass applications. The environmental sensors 272 may comprise, for example, one or more temperature sensors, one or more barometric pressure sensors, one or more ambient light sensors, one or more camera imagers, and / or one or more microphones, etc. The sensors 213 may generate analog and / or digital signals, and indications of the signals may be stored in memory 211 and processed by DSP 231 and / or processor 230 in support of one or more applications, such as, for example, applications directed to positioning and / or navigation operations.

[0026] The sensors 213 may be used in relative position measurement, relative position determination, motion determination, etc. Information detected by the sensors 213 may be used for motion detection, relative displacement, autonomous navigation, sensor-based position determination, and / or sensor-assisted position determination. The sensors 213 may be useful for determining whether the UE 200 is fixed (stationary) or mobile. In another example, for relative positioning information, the sensors / IMU may be used to determine the angle and / or orientation of other devices relative to the UE 200, etc.

[0027] The IMU 270 may be configured to provide measurements on the direction of motion and / or the speed of motion of the UE 200, which may be used in relative position determination. For example, one or more accelerometers 273 and / or one or more gyroscopes 274 of the IMU 270 may detect the linear acceleration and rotational velocity of the UE 200, respectively. The linear acceleration and rotational velocity measurements of the UE 200 may be integrated over time to determine an instantaneous direction of motion as well as a displacement of the UE 200. The instantaneous direction and displacement of motion may be integrated to track the position of the UE 200. For example, a reference position of the UE 200 may be determined for a certain instant, for example, using the SPS receiver 217 (and / or by some other means), and measurements from the accelerometers 273 and gyroscopes 274 obtained after this instant may be used in autonomous navigation to determine a current position of the UE 200 based on the movement (direction and distance) of the UE 200 compared to the reference position.

[0028] The magnetometer 271 may determine magnetic field strength in different directions, which may be used to determine an orientation of the UE 200. For example, the orientation may be used to provide the UE 200 with a digital compass. The magnetometer 271 may include a two-dimensional magnetometer configured to detect and provide an indication of the magnetic field strength in two orthogonal dimensions. Also or alternatively, the magnetometer 271 may include a three-dimensional magnetometer configured to detect and provide an indication of the magnetic field strength in three orthogonal dimensions. The magnetometer 271 may provide a means for sensing the magnetic field and providing an indication of the magnetic field, for example, to the processor 210.

[0029] The transceiver 215 may include a wireless transceiver 240 and a wired transceiver 250 configured to communicate with other devices over wireless and wired connections, respectively. For example, the wireless transceiver 240 may include a transmitter 242 and a receiver 244 coupled to one or more antennas 246 to transmit and / or receive wireless signals 248 and convert signals from the wireless signals 248 to wired (e.g., electrical and / or optical) signals and from the wired (e.g., electrical and / or optical) signals to the wireless signals 248. Thus, the transmitter 242 may include multiple transmitters, which may be separate components or combined / integrated components, and / or the receiver 244 may include multiple receivers, which may be separate components or combined / integrated components. The wireless transceiver 240 may be configured to communicate signals (e.g., with an access point and / or one or more other devices) according to various radio access technologies (RATs), such as IEEE 802.11 (including IEEE 802.11ax), WiFi, WiFi Direct (WiFi-D), Bluetooth, Zigbee, etc. The wired transceiver 250 may include a transmitter 252 and a receiver 254 configured for wired communication. The transmitter 252 may include multiple transmitters, which may be separate components or combined / integrated components, and / or the receiver 254 may include multiple receivers, which may be separate components or combined / integrated components. The wired transceiver 250 may be configured for optical and / or electrical communication, for example. The transceiver 215 may be communicatively coupled to the transceiver interface 214, for example, by an optical and / or electrical connection. The transceiver interface 214 may be at least partially integrated with the transceiver 215.

[0030] The user interface 216 may comprise one or more of several devices, such as, for example, a speaker, a microphone, a display device, a vibrating device, a keyboard, a touch screen, etc. The user interface 216 may include two or more of any of these devices. The user interface 216 may be configured to allow a user to interact with one or more applications hosted by the UE 200. For example, the user interface 216 may store in the memory 211 an indication of analog and / or digital signals to be processed by the DSP 231 and / or the general purpose processor 230 in response to an action from the user. Similarly, the applications hosted on the UE 200 may store in the memory 211 an indication of analog and / or digital signals to present output signals to the user. The user interface 216 may include audio input / output (I / O) devices, including, for example, a speaker, a microphone, digital-to-analog circuitry, analog-to-digital circuitry, amplifiers, and / or gain control circuits (including any two or more of these devices). Other configurations of audio I / O devices may be used. Also or alternatively, the user interface 216 may include one or more touch sensors that respond to contact and / or pressure, for example, on a keyboard and / or a touch screen of the user interface 216 .

[0031] The SPS receiver 217 (e.g., a Global Positioning System (GPS) receiver) may be capable of receiving and acquiring the SPS signals 260 via the SPS antenna 262. The antenna 262 is configured to convert the wireless signals 260 into wired signals, e.g., electrical or optical signals, and may be integrated with the antenna 246. The SPS receiver 217 may be configured to process the acquired SPS signals 260, in whole or in part, to estimate the location of the UE 200. For example, the SPS receiver 217 may be configured to use the SPS signals 260 to determine the location of the UE 200 by trilateration. The general-purpose processor 230, the memory 211, the DSP 231, and / or one or more specialized processors (not shown), together with the SPS receiver 217, may be used to process the acquired SPS signals, in whole or in part, and / or to calculate the estimated location of the UE 200. The memory 211 may store indications (e.g., measurements) of the SPS signals 260 and / or other signals (e.g., signals acquired from the wireless transceiver 240) for use in performing positioning operations. The general purpose processor 230, the DSP 231, and / or one or more specialized processors, and / or the memory 211 may provide or support a location engine for use in processing the measurements to estimate the location of the UE 200.

[0032] The UE 200 may include a camera 218 for capturing still or moving images. The camera 218 may comprise, for example, an imaging sensor (e.g., a charge-coupled device or CMOS imager), a lens, analog-to-digital circuitry, a frame buffer, etc. Additional processing, conditioning, encoding, and / or compression of signals representing the captured images may be performed by the general-purpose processor 230 and / or the DSP 231. Also or alternatively, a video processor 233 may perform conditioning, encoding, compression, and / or manipulation of signals representing the captured images. The video processor 233 may decode / decompress stored image data, for example, for presentation on a display device (not shown) of the user interface 216.

[0033] A positioning (motion) device (PMD) 219 may be configured to determine the location and possibly the movement of UE 200. For example, PMD 219 may be in communication with and / or include part or all of SPS receiver 217. PMD 219 may also or alternatively be configured to determine the location of UE 200 using terrestrial-based signals (e.g., at least some of signals 248) to assist in acquiring and using SPS signals 260 for trilateration, or both. PMD 219 may be configured to use one or more other techniques for determining the location of UE 200 (e.g., relying on the UE's self-reported location (e.g., part of the UE's location beacon)) and may use a combination of techniques (e.g., SPS signals and terrestrial positioning signals) to determine the location of UE 200. The PMD 219 may include one or more of the sensors 213 (e.g., gyroscopes, accelerometers, magnetometers, etc.) that may sense the orientation and / or movement of the UE 200 and provide an indication that the processor 210 (e.g., processor 230 and / or DSP 231) may be configured to use to determine the movement (e.g., velocity vector and / or acceleration vector) of the UE 200. The PMD 219 may be configured to provide an indication of uncertainty and / or error in the determined position and / or movement.

[0034] 3, an example of an access point (AP) 300, such as the AP 105, comprises a computing platform including a processor 310, a memory 311 including software (SW) 312, a transceiver 315, and (optionally) an SPS receiver 317. The processor 310, memory 311, transceiver 315, and SPS receiver 317 may be communicatively coupled to one another by a bus 320 (e.g., which may be configured for optical and / or electrical communications). One or more of the depicted devices (e.g., the wireless interface and / or the SPS receiver 317) may be omitted from the AP 300. The SPS receiver 317 may be configured similarly to the SPS receiver 217 to be capable of receiving and acquiring an SPS signal 360 via an SPS antenna 362. The processor 310 may include one or more intelligent hardware devices, e.g., a central processing unit (CPU), a microcontroller, an application specific integrated circuit (ASIC), or the like. The processor 310 may comprise multiple processors (e.g., including a general-purpose / application processor, a DSP, a modem processor, a video processor, and / or a sensor processor, as shown in FIG. 2). The memory 311 is a non-transitory storage medium and may include random access memory (RAM), flash memory, disk memory, and / or read-only memory (ROM), etc. The memory 311 stores the software 312, which may be processor-readable processor-executable software code including instructions that, when executed, are configured to cause the processor 310 to perform various functions described herein. Alternatively, the software 312 may not be directly executable by the processor 310, but may be configured, for example, when compiled and executed, to cause the processor 310 to perform functions. Although the description may only refer to the processor 310 performing functions, other implementations, such as the processor 310 executing software and / or firmware, are also included.The description may refer to the processor 310 performing a function as a shorthand for one or more of the processors included in the processor 310 performing the function. The processor 310 may include memory in addition to and / or in place of the memory 311 in which instructions are stored. The functionality of the processor 310 is described more fully below.

[0035] The transceiver 315 may include a wireless transceiver 340 and a wired transceiver 350 configured to communicate with other devices over wireless and wired connections, respectively. For example, the wireless transceiver 340 may include a transmitter 342 and a receiver 344 coupled to one or more antennas 346 to transmit (e.g., on one or more uplink channels) and / or receive (e.g., on one or more downlink channels) wireless signals 348 and convert signals from the wireless signals 348 to wired (e.g., electrical and / or optical) signals and from the wired (e.g., electrical and / or optical) signals to the wireless signals 348. Thus, the transmitter 342 may include multiple transmitters, which may be separate components or combined / integrated components, and / or the receiver 344 may include multiple receivers, which may be separate components or combined / integrated components. The wireless transceiver 340 may be configured to communicate signals (e.g., with the UE 200, one or more other UEs, and / or one or more other devices) according to various radio access technologies (RATs), such as IEEE 802.11 (including IEEE 802.11ax), WiFi, WiFi Direct (WiFi-D), Bluetooth, Zigbee, etc. The wired transceiver 350 may include a transmitter 352 and a receiver 354 configured for wired communication. The transmitter 352 may include multiple transmitters, which may be separate components or combined / integrated components, and / or the receiver 354 may include multiple receivers, which may be separate components or combined / integrated components. The wired transceiver 350 may be configured for optical and / or electrical communication, for example.

[0036] Referring to FIG. 4, a conceptual diagram 400 of radio frequency sensing with simultaneous transmission and reception by a wireless device is shown. A wireless device, such as a UE 200 or an AP 300, includes a transceiver 240, 340 having multiple transmit and receive chains configured for simultaneous transmission and reception of RF signals. The number of transmit and receive chains in FIG. 4 is exemplary and not limiting, as other transceiver and antenna configurations may be used. For example, the transceiver 240 may be configured for multiple-input multiple-output (MIMO) with two transmit chains and two receive chains. Other array sizes and configurations may be used. In one example, the transceiver 240 may include a transmit chain including a transmit antenna 402 operably coupled to a transmit RF module 408. The transmit RF module 408 is configured to receive a signal from a digital-to-analog converter (DAC) 406 and transmit a corresponding RF signal via the transmit antenna 402. The signal may be generated by a processor, such as the modem processor 232 and / or the application processor 230. The transceiver 240 may include one or more receive chains including a receive antenna 404, a receive RF module 416, and an analog-to-digital converter (ADC) 414. Additional receive modules, such as a second receive chain 420 and a third receive chain 422, may also be used.

[0037] In operation, the wireless device may transmit a radio frequency signal 412a towards a target 418. The reflected signal 412b is the portion of the RF signal 412a that is reflected by the target 418 and received by one or more receive antennas, such as the receive antenna 404. The additional receive chain may enable beamforming / direction finding to allow the wireless device to calculate the angle of arrival (AoA) of the received signal. The receive chain may also receive a transmit leakage signal 410 simultaneously with the transmission of the RF signal 412a. The transmit leakage 410 may be conductive and / or radiated interference, depending on the configuration of the wireless device. For example, physical shielding may be used to reduce radiated interference between the transmit and receive antennas. In one embodiment, the radio frequency signal 412a may be a pre-designed sequence having a length "L". The pre-designed sequence may be designed to have cyclic autocorrelation properties, such as a single carrier Zadoff-Chu sequence, or an orthogonal frequency division multiplexing (OFDM)-like symbol. The sequence may be transmitted repeatedly and continuously for "n" times such that the receive chain of the wireless device may begin listening at a time after length "L" to receive the sequence without losing signal information. This relaxed time requirement on the receive chain means that the receive chain does not have to start at the same time as the transmitter.

[0038] The receive RF module 416 (and additional receive chains 420, 422) may listen and receive “m” sequences instead of one sequence. For example, the receive RF module 416 may listen to a length of m*L, where “m” is the number of sequences captured by the receive RF module 416, and m<=n. The UE 200 may combine the received “m” sequences to improve the signal-to-noise ratio (SNR). The received sequences may be used for RF sensing. For example, a known transmit sequence may be utilized to obtain a channel estimate based on a signal correlation technique. The channel estimate may be processed via an iterative cancellation algorithm to detect leakage and reflections. The time difference between the leakage and reflections may be used to estimate the distance to the target 418. Multiple Rx antennas, such as additional receive chains 420, 422, may be utilized to receive the sequence of the reflected signal 412b, determine a channel estimate, and obtain an angle estimate for the reflected signal 412b. The changes in the channel estimation may be utilized to detect movement of the target 418. Classification algorithms and / or machine learning on the channel estimation results may be used to identify the type and / or size of movement of the target 418. In one example, the channel estimation may be used to detect changes in the pose of the target 418.

[0039] The number of transmit and receive chains of the wireless device of Figure 4 is by way of example only and is not limiting. Other wireless devices may have multiple arrays, each consisting of a different number and pattern of antenna elements. For example, an antenna array may include a matrix of elements at 1x2, 1x4, 1x5, 1x8, 2x2, 2x4, 2x5, 2x8, 3x4, 3x5, 3x8, etc. Other antenna array matrix dimensions may also be used.

[0040] In one embodiment, a wireless device having one or more multi-element antenna arrays may be configured to beamform the transmit and receive RF signals. For example, the transceiver 240 may include a radio frequency integrated circuit (RFIC) including a phase shifter to modify the transmit beam gain and the receive beam gain. The wireless device may be configured to vary the angle of departure (AoD) of the RF signal 412a. In one example, the RF signal 412a may be swept through different AoDs and the gain of the corresponding reflected signal may be determined. Varying the AoD of the RF signal 412a may be used to determine a direct path to the target 418 (e.g., based on the highest reflected gain). In one example, the beam sweep may be used to determine the changing attitude of the object (e.g., based on a series of reflected signals over time). In one embodiment, the transmit RF signal 412a may be a polarized signal and the polarization of the receive signal 412b may be detected. The change in polarization between the transmit and receive signals may be used to determine the characteristics and / or classification of the target 418.

[0041] With reference to FIG. 5 and further with reference to FIG. 4, a graph 500 of an exemplary received signal is shown. The graph 500 includes a relative power axis 502, a time axis 504, and a signal response function 506. The signal response function 506 represents a signal detected by the receive antenna 404. A first peak 508 is based on the transmit leakage 410, and a second peak 510 is based on the reflected signal 412b. The RF receiver 416 (and other receive chains 420, 422) may be configured to reduce the receive gain for the duration of the transmission of the RF signal 412a. For example, one or more amplifier components (e.g., low noise amplifiers (LNAs)) in the receiver may be configured to have an adjustable gain function. The receive gain may be reduced to reduce the effect of the leakage on the receive chain. Other iterative cancellation algorithms may be used to reduce the effect of the first peak 508 and improve detection of the second peak 510. The transmit gain of the RF transmit module 408 may be increased to improve detection of the reflected signal 412b. For example, the transmit gain may be iteratively increased for each of the sequences based on the value of the peak associated with the reflected signal 412b.

[0042] In operation, the signal response function 506 includes the transmitted sequence and the corresponding ADC capture in the ADC module 414 is equivalent to the channel capture and can be utilized to enable channel capture based RF sensing use cases. The time difference between the first peak 508 (i.e., the transmission time) and the second peak 510 (i.e., the reflected signal 412b) can be utilized to estimate the distance to the target 418. The AoA of the reflected signal 412b can be obtained based on the ADC capture from multiple antennas (e.g., additional receive chains 420, 422). The measured distance and direction information to the target 418 can be used in indoor mapping applications. The bandwidth of the transmitted RF signal 412a can vary and is not limited to the Wi-Fi packet bandwidth. For example, the wide bandwidth can be based on the DAC and ADC rates and analog filter bandwidth that may be larger than the Wi-Fi packet bandwidth. The transmission and reception of the RF signal 412a can be performed within hundreds of microseconds, and therefore the impact on the Wi-Fi communication can be minimal. Thus, the RF sensing techniques described herein may be used simultaneously with Wi-Fi data exchange functions. Referring to FIG. 6, a conceptual diagram 600 of intra-chain transmission and reception by a wireless device is shown. A wireless device, such as a UE 200 or an AP 300, includes a transceiver 602 having one or more transmit and receive chains. The number of transmit and receive chains in FIG. 6 is exemplary and not limiting, as other transceiver and antenna configurations may be used. For example, the transceiver 602 may be configured for multiple-input multiple-output (MIMO) with two transmit chains and two receive chains. Other array sizes and configurations may be used. In general, transmit and receive chains are conceptual terms that refer to the hardware required for transmit / receive signal processing. A MIMO radio may be configured to add signal components from multiple antennas. Single-chain transmit and receive operations may utilize a single antenna for transmit and receive functions. In one example, a first transceiver chain 604 is configured for single-chain Tx and Rx operation. The transceiver 602 may include additional transceiver chains 606a, 606b configured for single-chain or independent Tx and Rx operation. The first transceiver chain 604 is configured to transmit an RF signal 608a toward a target 610 and then receive a reflected RF signal 608b. For example, the first transceiver chain 604 may be configured to switch between ports of a directional coupler to enable intra-chain Tx and Rx operations. In an embodiment, the additional transceiver chains 606a, 606b may also receive respective reflected signals 608c, 608d. The RF signal 608a may be a single carrier Zadoff-Chu sequence or orthogonal frequency division multiplexing symbols (OFDM), as described in FIG. 4, or other orthogonal resources configured to optimize synchronization and channel estimation performance. In an example, a wireless device may utilize multiple Tx and multiple Rx using MIMO for improved channel information capture, such as through the use of existing MIMO preamble long training field (LTF) sequences. Other sequences and signals may also be used.

[0043] With reference to FIG. 7 and with further reference to FIGS. 1-6, a method 700 for setting a transmit gain for radio frequency sensing includes the steps shown. In general, the method 700 may be used to set a transmit gain for an RF signal to increase a received signal strength indication (RSSI) while reducing receiver saturation. However, the method 700 is exemplary only and not limiting. The method 700 may be modified, for example, by adding, deleting, reordering, combining, performing simultaneously steps, and / or splitting a single step into multiple steps.

[0044] In stage 702, the method includes setting a first transmit gain to avoid receiver saturation. The transmit RF module 408 is a means for setting the first transmit gain. A transceiver in a wireless device such as the UE 200 and the AP 300 may be configured to modify (e.g., adjust Tx power) the output gain of one or more transmitter chains such as the transmit RF module 408. The RF module 408 may transmit a first RF signal at a low transmit gain (e.g., Tx Gain_1) that is safe enough to avoid receiver saturation. The receiver saturation may be determined based on an amount of signal clipping observed in the received signal. The value of Tx Gain_1 may be selected such that the received signal is not distorted due to clipping or other attenuation due to signal saturation. In one example, the value of Tx Gain_1 may be stored in a memory and used for initial transmission in an RF sensing application.

[0045] In stage 704, the method includes transmitting a first signal using a first transmit gain. The transmit RF module 408 is a means for transmitting the first signal using the first transmit gain. For example, referring to FIG. 4, the first signal may be the RF signal 412a. The first signal may be a first Wi-Fi RF sensing packet, or a single carrier Zadoff-Chu sequence, or other RF signal such as an OFDM LTF-like symbol.

[0046] In stage 706, the method includes receiving a reflection of the first signal and estimating a transmit gain adjustment value. The receive RF module 416 is a means for receiving a reflection of the first signal, and the processor 230 may be a means for estimating a transmit gain adjustment value. With reference to FIG. 4, the reflected signal may be the reflected signal 412b. In one example, the processor 230, or another processor in the wireless device, may be configured to determine a remaining headroom in the ADC 414 based on the first signal. The headroom may be based on the amplitude of a time-varying signal (e.g., a peak of a sine wave) or a level of clipping in an orthogonal signal (e.g., an OFDM-like symbol). The increase in transmit gain may be based on the available remaining headroom. The transmit gain adjustment may be a value Tx Gain_delta representing an estimate of a transmit gain increase to improve the RSSI without saturating the receiver.

[0047] At stage 708, the method includes transmitting a second signal using the transmit gain adjustment value. The transmit RF module 408 is a means for transmitting the second signal. The transmit RF module 408 may transmit another Wi-Fi RF sensing packet, or other RF signal, with a transmitter gain equal to the first transmit gain (i.e., Tx Gain _1) plus the transmit gain adjustment value (i.e., TX Gain_delta). Thus, the signal may have a transmit gain value TX Gain_2=Tx Gain _1+TX Gain_delta.

[0048] At stage 710, the method includes receiving a reflection of the second signal and estimating a transmit gain adjustment value. The receive RF module 416 may be a means for receiving the second signal, and the processor 230 may be a means for estimating the transmit gain adjustment value. In one example, the processor 230, or another processor in the wireless device, may be configured to determine the remaining headroom in the ADC 414 based on the signal transmitted at stage 708 (e.g., at a transmit gain of Tx Gain_2). The processor 230 may be configured to adjust the transmit gain adjustment value based on the amplitude of a time-varying signal (e.g., a peak of a sine wave) or a level of clipping in an orthogonal signal (e.g., an OFDM-like symbol), as previously described. The transmit gain value may be adjusted, and the process may repeat back to stage 708 based on the adjusted transmit gain value on the additional signal.

[0049] Method 700 may be used to set a transmit gain value when a wireless device is initialized and Wi-Fi RF sensing functionality is activated. Method 700 may also be executed periodically or based on a trigger condition, such as a change in location, a change in the surrounding environment, or a change in hardware or software is detected. Other trigger conditions, such as when an abnormal RSSI value or ADC clipping is detected, may also be used to initialize method 700.

[0050] With reference to FIG. 8 and with further reference to FIGS. 1-6, a method 800 for setting a receiver gain for radio frequency sensing includes the stages shown. In general, the method 800 may be used to set a receiver gain for an RF signal to improve ADC range, reduce quantization noise and clipping, and improve detection of weak signals. However, the method 800 is exemplary only and not limiting. The method 800 may be modified, for example, by adding, deleting, reordering, combining, performing simultaneously stages, and / or splitting a single stage into multiple stages.

[0051] In stage 802, the method includes setting a first receiver gain and receiving a first signal. The receive RF module 416 is a means for setting the first receiver gain and receiving the first signal. The first receiver gain value (i.e., Rx Gain_1) may be a pre-established value stored in memory and set when the receive RF module 416 is initialized. The first signal may be a reflected signal 412b comprising a first Wi-Fi RF sensing packet, or other RF signal such as a single carrier Zadoff-Chu sequence, or an OFDM LTF-like symbol.

[0052] At stage 804, the method includes estimating a reduced receiver gain value. The processor 230 may be a means for estimating the reduced receiver gain value. In one example, the processor 230, or another processor in the wireless device, may be configured to determine the degree of received signal clipping occurring at the ADC 414. The clipping may be based on the expected amplitude of a time-varying signal (e.g., a peak of a sine wave) or the level of clipping of resources in an orthogonal signal (e.g., an OFDM-like symbol). The receiver gain may be reduced by a value Rx Gain_delta, which represents a proportional reduction in receiver gain based on the ADC range and the level of clipping in the received signal. The first receiver gain is reduced by the estimated value (i.e., Rx Gain_2=Rx Gain_1-Rx Gain_delta).

[0053] In stage 806, the method includes receiving a second signal using the reduced receiver gain. The receive RF module 416 is a means for receiving the second signal. The second signal may be another reflected signal 412b including a second Wi-Fi RF sensing packet, or another RF signal as described above. The method 800 may repeat back to stage 804 and determine whether the receive gain value requires additional adjustment based on the quality of the signal at the ADC 414. The method 800 may be used to set the receiver gain value when the wireless device is initialized and the Wi-Fi RF sensing function is activated. The method 800 may also be executed periodically or based on a trigger condition, such as a change in location, a change in the surrounding environment, or a change in hardware or software is detected. Other trigger conditions, such as when an abnormal RSSI value or ADC clipping is detected, may also be used to initialize the method 800.

[0054] In operation, the wireless device may be configured to clear the channel before transmitting the RF sensing signal to avoid collisions with other Wi-Fi frames. In one example, the device may transmit a Clear-to-Send (CTS) to itself in the same bandwidth as the RF sensing signal to clear the channel. In another example, the device may transmit an existing Wi-Fi legacy preamble format to ensure that other devices have priority for the RF sensing signal. In another example, the device is configured to transmit the RF sensing signal within a short interframe space (SIFS) after a transmit or end of a receive packet. Other methods may also be used to verify that the channel is clear.

[0055] 9, and with further reference to FIGS. 1-8, a method 900 for controlling a receiver in a wireless device for radio frequency sensing includes the steps shown. However, the method 900 is by way of example only and not by way of limitation. The method 900 may be modified, for example, by adding, deleting, reordering, combining, performing simultaneously steps, and / or splitting a single step into multiple steps.

[0056] At stage 902, the method includes setting a receive gain on a wireless device to a first level. The receive RF module 416 is a means for setting the receive gain to a first level. In one example, a wireless device such as the UE 200 or the AP 300 is configured to reduce the gain on one or more receive chains during a period in which the RF sensing signal is transmitted. For example, the RF receiver 416 (and other receive chains 420, 422) may be configured to reduce the receive gain for the duration of the transmission of the RF signal 412a. In one embodiment, one or more amplifier components (e.g., LNAs) in the receiver may be configured to have an adjustable gain function, and the receive gain may be reduced to reduce the effect of leakage on the receive chain.

[0057] At stage 904, the method includes transmitting a radio frequency signal at a wireless device at a first time, where a leakage signal is received by the wireless device at a first level of receive gain. The transmit RF module 408 is a means for transmitting a radio frequency signal. With reference to FIG. 4, the leakage signal may be a leakage signal 410 received simultaneously with the transmission of the RF signal. In one example, the RF signal may be a pre-designed sequence designed to have cyclic autocorrelation properties, such as a single carrier Zadoff-Chu sequence, or an OFDM LTF-like symbol. The first time may be based on the time at which one RF signal in the sequence is transmitted. The sequence may be repeatedly and continuously transmitted for "n" times such that a receive chain of the UE 200 or AP 300 may start listening at a time after the length "L" to receive the sequence without losing signal information. In one embodiment, the method 700 may be used to set a transmitter gain of the RF signal.

[0058] In stage 906, the method includes setting a receive gain on the wireless device to a second level. The receive RF module 416 is a means for setting the receive gain to the second level. The second level may be an increase in receiver gain compared to the first level. That is, an LNA in the receive gain may be configured to increase sensitivity to detect the reflected signal 412b. The increase in receiver gain occurs after the transmission in stage 904. In one embodiment, the method 800 may be used to set a value of the second receive gain level.

[0059] At stage 908, the method includes receiving a reflection of the radio frequency signal at a second time at the wireless device, where the receive gain is at a second level. The receive RF module 416 is a means for receiving the reflected radio frequency signal. The reflected radio frequency signal received at the second time may be a reflected RF signal 412b and may be received by one or more receive chains (e.g., additional receive chains 420, 422). In an example, the receive RF module 416 may listen using an increased Rx gain value of the second peak 510 received at the second time. The receive RF module 416 may also listen and receive "m" sequences instead of one sequence. For example, the receive RF module 416 may listen for a length of m*L, where "m" is the number of sequences captured by the receive RF module 416, and m<=n. The wireless device may combine the received "m" sequences to improve a signal-to-noise ratio (SNR) of the reflected signal.

[0060] At stage 910, the method includes determining a distance to the object based at least in part on the difference between the first time and the second time. The processor 230 of the UE 200 and the processor 310 of the AP 300 are means for determining the distance. The difference between the transmission time (i.e., the first time) and the reception time (i.e., the second time) represents the round-trip flight time of the transmitted signal 412a and the reflected signal 412b. In one example, the distance may be calculated as half the time difference multiplied by the speed of light. Other error correction and bias values ​​may also be used in the distance calculation. For example, additional values ​​such as RSSI and AoA may be used to determine the range, azimuth, and orientation of the target.

[0061] With reference to Figure 10 and with further reference to Figures 1-8, a method 1000 for determining distance to an object using radio frequency sensing includes the steps shown. However, method 1000 is by way of example only and not by way of limitation. Method 1000 may be modified, for example, by adding, removing, reordering, combining, performing simultaneously steps, and / or splitting a single step into multiple steps.

[0062] In stage 1002, the method includes transmitting a radio frequency signal using a transmission channel on the wireless device. The transmit RF module 408 is a means for transmitting the radio frequency signal. The radio frequency signal may be one or more Wi-Fi packets or other RF signals transmitted from one or more transmit antennas 402. In general, a Wi-Fi packet is a term for electronic transmission of data in a Wi-Fi network. In one embodiment, the wireless device may be configured to transmit multiple RF signals from one or more transmitters and transmit antennas. In one example, the RF signals may be pre-designed sequences designed to have cyclic autocorrelation properties, such as single carrier Zadoff-Chu sequences, or OFDM LTF-like symbols. The first time may be based on the time at which one RF signal in the sequence is transmitted. The sequence may be repeatedly and continuously transmitted for "n" times such that the receive chain of the UE 200 or AP 300 may start listening at a time after the length "L" to receive the sequence without losing signal information. In one embodiment, the transmitter gain of the RF signal may be determined based on the method 700 and stored in memory for use when the RF sensing application is launched.

[0063] At step 1004, the method includes receiving a leakage signal using a receive channel on the device at a first time, where the leakage signal is based on a radio frequency signal. The receive RF module 416 is a means for receiving the leakage signal. In one example, one or more receive chains in the wireless device may receive a transmit leakage signal 410 simultaneously with the transmission of the RF signal at step 1002. The transmit leakage 410 may be conductive and / or radiated interference, depending on the configuration of the wireless device. The wireless device is configured to determine a time at which one or more RF leakage signals are received. The leakage signal may be received at two or more receive chains at a timing of a TX leakage peak (e.g., the first peak 508).

[0064] In stage 1006, the method includes receiving a reflected signal using a receive channel on the device at a second time, the reflected signal being based on a radio frequency signal reflecting from the object. The receive RF module 416 is a means for receiving the reflected signal. The radio frequency signal received at the second time may be a reflected RF signal 412b and may be received by one or more receive chains (e.g., additional receive chains 420, 422). In one example, the receive RF module 416 may listen and receive "m" sequences instead of one sequence. For example, the receive RF module 416 may listen for a length of m*L, where "m" is the number of sequences captured by the receive RF module 416, and m<=n. The wireless device may combine the received "m" sequences to improve the signal-to-noise ratio (SNR) of the reflected signal. In one embodiment, a receiver gain for receiving the RF signal may be determined based on the method 800 and stored in memory for use when the RF sensing application is launched.

[0065] In stage 1008, the method includes determining a distance to the object based at least in part on the difference between the first time and the second time. The processor 230 of the UE 200 and the processor 310 of the AP 300 are means for determining the distance. The difference between the time the leaking signal is received (i.e., the first time) and the time of reception (i.e., the second time) represents the round-trip flight time of the transmitted signal 412a and the reflected signal 412b. In one example, the distance may be calculated as half the time difference multiplied by the speed of light. Other error correction and bias values ​​may also be used in the distance calculation. For example, additional values ​​such as RSSI and AoA may be used to determine the range, azimuth, and orientation of the target.

[0066] In an embodiment, the method 1000 may include one or more additional features. For example, the radio frequency signal may be a pre-specified sequence. A single carrier Zadoff-Chu sequence, an orthogonal frequency division multiplexing symbol, one or more Wi-Fi packets are examples of pre-specified sequences. Multiple radio frequency signals may be transmitted and received. Multiple radio frequency signals may be transmitted using multiple transmission channels. Radio frequency signals may be received using multiple receive chains. Angle of Arrival (AoA) of the received RF signal and Angle of Departure (AoD) of the transmitted signal may be determined. Transmitting the radio frequency signal and receiving the radio frequency signal may be performed using single chain transmit and receive operations.

[0067] Other examples and implementations are within the scope and spirit of the present disclosure and the appended claims. For example, due to the nature of software and computers, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination of these. Features implementing the functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented in various physical locations.

[0068] As used herein, the singular forms "a," "an," and "the" include the plural unless the context clearly indicates otherwise. For example, "a processor" may include one processor or multiple processors. As used herein, the terms "comprises," "comprising," "including," and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0069] Also, as used herein, "or" used in a list of items beginning with "at least one of" or "one or more of" indicates a disjunctive list, such as a list of "at least one of A, B, or C" or a list of "one or more of A, B, or C" meaning A, or B, or C, or AB, or AC, or BC, or ABC (i.e., A and B and C), or a combination of two or more features (e.g., AA, AAB, ABBC, etc.).

[0070] Substantial variations may be made according to particular requirements. For example, customized hardware may also be used and / or particular elements may be implemented in hardware, software executed by a processor (including portable software such as applets), or both. Furthermore, connection to other computing devices, such as network input / output devices, may be employed.

[0071] The systems and devices described above are examples. Various configurations may omit, substitute, or add various procedures or components, as appropriate. For example, features described with respect to some configurations may be combined in various other configurations. Different aspects and elements of the configurations may be combined in a similar manner. Also, technology evolves, and thus many of the elements are examples and do not limit the scope of the disclosure or claims.

[0072] A wireless communication system is a communication system in which communications are conveyed wirelessly, i.e., by electromagnetic and / or sound waves propagating through atmospheric space rather than through wires or other physical connections. A wireless communication network is configured to cause at least some, but not all, communications to be transmitted wirelessly. Furthermore, the term "wireless communication device" or similar terms does not require that the function of the device be exclusively or even primarily for communication or that the device be a mobile device, but indicates that the device includes wireless communication capabilities (unidirectional or bidirectional), e.g., at least one radio for wireless communication (each radio being part of a transmitter, receiver, or transceiver).

[0073] Specific details are given in the description to provide a thorough understanding of the example configurations (including implementations). However, the configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques are shown without unnecessary details to avoid obscuring the configurations. This description only provides an example configuration and does not limit the scope, applicability, or configuration of the claims. Rather, the preceding description of the configurations provides a description for implementing the described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the present disclosure.

[0074] As used herein, the terms "processor-readable medium," "machine-readable medium," and "computer-readable medium" refer to any medium that participates in providing data that causes a machine to operate in a specific manner. When using a computing platform, various processor-readable media may be involved in providing instructions / code to the processor for execution and / or may be used to store and / or carry such instructions / code (e.g., signals). In many implementations, the processor-readable medium is a physical and / or tangible storage medium. Such media may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media include, for example, optical and / or magnetic disks. Volatile media include, but are not limited to, dynamic memory.

[0075] A statement that a value exceeds (i.e., is greater than or exceeds) a first threshold is equivalent to a statement that the value meets or exceeds a second threshold that is slightly greater than the first threshold, e.g., the second threshold is a value that is higher than the first threshold at the resolution of the computing system. A statement that a value is less than (i.e., is within or below) a first threshold is equivalent to a statement that the value is less than or equal to a second threshold that is slightly lower than the first threshold, e.g., the second threshold is a value that is lower than the first threshold at the resolution of the computing system.

[0076] Example implementations are described in the following numbered clauses.

[0077] Clause 1. A method for determining a distance to an object using radio frequency sensing, the method including: transmitting a radio frequency signal using a transmit channel on a wireless device; receiving a leakage signal using a receive channel on the wireless device at a first time, where the leakage signal is based on the radio frequency signal; receiving a reflected signal using a receive channel on the wireless device at a second time, where the reflected signal is based on the radio frequency signal reflecting from the object; and determining a distance to the object based at least in part on a difference between the first time and the second time.

[0078] Clause 2. The method of clause 1, wherein the radio frequency signal is a pre-specified sequence.

[0079] Clause 3. The method of clause 2, wherein the pre-specified sequence is a single-carrier Zadoff-Chu sequence.

[0080] Clause 4. The method of clause 2, wherein the pre-specified sequence includes orthogonal frequency division multiplexing symbols.

[0081] Clause 5. The method of clause 2, wherein the pre-specified sequence includes one or more Wi-Fi packets.

[0082] Clause 6. The method of clause 1, further comprising transmitting a plurality of radio frequency signals and receiving one or more of the plurality of radio frequency signals.

[0083] Clause 7. The method of clause 1, further comprising transmitting a plurality of radio frequency signals using a plurality of transmission channels.

[0084] Clause 8. The method of clause 1, wherein receiving a radio frequency signal includes receiving a radio frequency signal using a plurality of receive chains.

[0085] Clause 9. The method of clause 8, further comprising determining an angle of arrival of the received radio frequency signal.

[0086] Clause 10. The method of clause 1, further comprising determining an angle of departure of the radio frequency signal.

[0087] Clause 11. The method of clause 1, wherein the steps of transmitting a radio frequency signal and receiving a radio frequency signal are performed using single chain transmit and receive operations.

[0088] Clause 12. An apparatus, comprising: a memory; at least one transceiver including at least one transmit chain and at least one receive chain; and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: transmit a radio frequency signal with the at least one transmit chain; receive a leakage signal with the at least one receive chain at a first time, where the leakage signal is based on the radio frequency signal; receive a reflected signal with the at least one receive chain at a second time, where the reflected signal is based on the radio frequency signal reflecting from the object; and determine a distance to the object based at least in part on a difference between the first time and the second time.

[0089] Clause 13. The apparatus of clause 12, wherein the radio frequency signal is a pre-specified sequence.

[0090] Clause 14. The apparatus of clause 13, wherein the pre-specified sequence is a single-carrier Zadoff-Chu sequence.

[0091] Clause 15. The apparatus of clause 13, wherein the pre-specified sequence includes orthogonal frequency division multiplexing symbols.

[0092] Clause 16. The apparatus of clause 13, wherein the pre-specified sequence includes one or more Wi-Fi packets.

[0093] Clause 17. The apparatus of clause 12, wherein the at least one processor is further configured to transmit the plurality of radio frequency signals and receive one or more of the plurality of radio frequency signals.

[0094] Clause 18. The apparatus of clause 12, wherein the at least one processor is further configured to transmit a plurality of radio frequency signals using a plurality of transmit chains.

[0095] Clause 19. The apparatus of clause 12, wherein the at least one processor is further configured to receive radio frequency signals using multiple receive chains.

[0096] Clause 20. The apparatus of clause 19, wherein the at least one processor is further configured to determine an angle of arrival of the received radio frequency signal.

[0097] Clause 21. The apparatus of clause 12, wherein the at least one processor is further configured to determine an angle of departure of the radio frequency signal.

[0098] Clause 22. The apparatus of clause 12, wherein the at least one processor is configured to transmit radio frequency signals and receive radio frequency signals using single chain transmit and receive operations.

[0099] Clause 23. An apparatus for determining distance to an object using radio frequency sensing, the apparatus including: means for transmitting a radio frequency signal using a transmit channel on a wireless device; means for receiving a leakage signal using a receive channel on the wireless device at a first time, where the leakage signal is based on the radio frequency signal; means for receiving a reflected signal using a receive channel on the wireless device at a second time, where the reflected signal is based on the radio frequency signal reflecting off the object; and means for determining a distance to the object based at least in part on a difference between the first time and the second time.

[0100] Clause 24. The apparatus of clause 23, wherein the radio frequency signal is a pre-specified sequence.

[0101] Clause 25. The apparatus of clause 24, wherein the pre-specified sequence is a single-carrier Zadoff-Chu sequence.

[0102] Clause 26. The apparatus of clause 24, wherein the prespecified sequence includes orthogonal frequency division multiplexing symbols.

[0103] Clause 27. The apparatus of clause 24, wherein the pre-specified sequence includes one or more Wi-Fi packets.

[0104] Clause 28. The apparatus of clause 23, further comprising means for transmitting the plurality of radio frequency signals and means for receiving one or more of the plurality of radio frequency signals.

[0105] Clause 29. The apparatus of clause 23, further comprising means for transmitting a plurality of radio frequency signals using a plurality of transmission channels.

[0106] Clause 30. The apparatus of clause 23, wherein the means for receiving radio frequency signals includes means for receiving radio frequency signals with a plurality of receive chains.

[0107] Clause 31. The apparatus of clause 30, further comprising means for determining an angle of arrival of a received radio frequency signal.

[0108] Clause 32. The apparatus of clause 23, further comprising means for determining an angle of departure of the radio frequency signal.

[0109] Clause 33. The apparatus of clause 23, wherein the means for transmitting radio frequency signals and the means for receiving radio frequency signals are performed using single chain transmit and receive operations.

[0110] Clause 34. A non-transitory processor-readable storage medium containing processor-readable instructions to cause one or more processors to determine a distance to an object using radio frequency sensing, the non-transitory processor-readable storage medium including: code for transmitting a radio frequency signal using a transmit channel on a wireless device; code for receiving a leakage signal using a receive channel on the wireless device at a first time, where the leakage signal is based on the radio frequency signal; code for receiving a reflected signal using a receive channel on the wireless device at a second time, where the reflected signal is based on the radio frequency signal reflecting from the object; and code for determining a distance to the object based at least in part on a difference between the first time and the second time.

[0111] Clause 35. The non-transitory processor-readable storage medium of clause 34, wherein the radio frequency signals are a pre-specified sequence.

[0112] Clause 36. The non-transitory processor-readable storage medium of clause 35, wherein the pre-specified sequence is a single-carrier Zadoff-Chu sequence.

[0113] Clause 37. The non-transitory processor-readable storage medium of clause 35, wherein the pre-specified sequence includes orthogonal frequency division multiplexing symbols.

[0114] Clause 38. The non-transitory processor-readable storage medium of clause 35, wherein the pre-specified sequence includes one or more Wi-Fi packets.

[0115] Clause 39. The non-transitory processor-readable storage medium of clause 34, further comprising code for transmitting the plurality of radio frequency signals and code for receiving one or more of the plurality of radio frequency signals.

[0116] Clause 40. The non-transitory processor-readable storage medium of clause 34, further comprising code for transmitting a plurality of radio frequency signals using a plurality of transmission channels.

[0117] Clause 41. The non-transitory processor-readable storage medium of clause 34, wherein the code for receiving radio frequency signals includes code for receiving radio frequency signals with a plurality of receive chains.

[0118] Clause 42. The non-transitory processor-readable storage medium of clause 41, further comprising code for determining an angle of arrival of a received radio frequency signal.

[0119] Clause 43. The non-transitory processor-readable storage medium of clause 34, further comprising code for determining an angle of departure of the radio frequency signal.

[0120] Clause 44. A method of setting a transmit gain for radio frequency sensing, the method comprising: setting a first transmit gain to avoid receiver saturation, transmitting a first signal using the first transmit gain, receiving a reflection of the first signal and estimating a transmit gain adjustment value, transmitting a second signal using the transmit gain adjustment value, receiving a reflection of the second signal and estimating a transmit gain adjustment value.

[0121] Clause 45. An apparatus, comprising: a memory; at least one transceiver including at least one transmit chain and at least one receive chain; and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: set a first transmit gain to avoid receiver saturation, transmit a first signal using the first transmit gain, receive a reflection of the first signal and estimate a transmit gain adjustment value, transmit a second signal using the transmit gain adjustment value, receive a reflection of the second signal and estimate the transmit gain adjustment value.

[0122] Clause 46. An apparatus for setting a transmit gain for radio frequency sensing, the apparatus including: means for setting a first transmit gain to avoid receiver saturation; means for transmitting a first signal using the first transmit gain; means for receiving a reflection of the first signal and estimating a transmit gain adjustment value; means for transmitting a second signal using the transmit gain adjustment value; and means for receiving a reflection of the second signal and estimating the transmit gain adjustment value.

[0123] Clause 47. A non-transitory processor-readable storage medium including processor-readable instructions to cause one or more processors to set a transmit gain for radio frequency sensing to avoid saturation of a receiver, the non-transitory processor-readable storage medium including code for setting a first transmit gain, code for transmitting a first signal using the first transmit gain, code for receiving a reflection of the first signal and estimating a transmit gain adjustment value, code for transmitting a second signal using the transmit gain adjustment value, and code for receiving a reflection of the second signal and estimating the transmit gain adjustment value.

[0124] Clause 48. A method for controlling a receiver in a wireless device for radio frequency sensing, the method including the steps of: setting a receive gain on the wireless device to a first level; transmitting a radio frequency signal at the wireless device at a first time, where the leakage signal is received by the wireless device at the first level of receive gain; setting a receive gain on the wireless device to a second level; receiving a reflection of the radio frequency signal at the wireless device at a second time, where the receive gain is at the second level; and determining a distance to an object based at least in part on a difference between the first time and the second time.

[0125] Clause 49. An apparatus, comprising: a memory; at least one transceiver including at least one transmit chain and at least one receive chain; and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: set a receive gain on a wireless device to a first level; transmit a radio frequency signal at the wireless device at a first time, where a leakage signal is received by the wireless device at the first level of receive gain; set a receive gain on the wireless device to a second level; receive a reflection of the radio frequency signal at the wireless device at a second time, where the receive gain is at the second level; and determine a distance to the object based at least in part on a difference between the first time and the second time.

[0126] Clause 50. An apparatus for controlling a receiver in a wireless device for radio frequency sensing, the apparatus including: means for setting a receive gain on the wireless device to a first level; means for transmitting a radio frequency signal at the wireless device at a first time, where the leakage signal is received by the wireless device at the first level of receive gain; means for setting a receive gain on the wireless device to a second level; means for receiving a reflection of the radio frequency signal at the wireless device at a second time, where the receive gain is at the second level; and means for determining a distance to an object based at least in part on a difference between the first time and the second time.

[0127] Clause 51. A non-transitory processor-readable storage medium containing processor-readable instructions to cause one or more processors to control a receiver in a wireless device for radio frequency sensing, the non-transitory processor-readable storage medium including: code for setting a receive gain on the wireless device to a first level; code for transmitting a radio frequency signal at the wireless device at a first time, where the leakage signal is received by the wireless device at the first level of receive gain; code for setting a receive gain on the wireless device to a second level; code for receiving a reflection of the radio frequency signal at the wireless device at a second time, where the receive gain is at the second level; and code for determining a distance to an object based at least in part on a difference between the first time and the second time. [Explanation of symbols]

[0128] 100 WLAN networks 105 Access Points 110 Wireless Devices 125 Geographic Coverage Areas 200UE 210 Processor 211 Memory 212 Software (SW) 213 Sensor 214 Transceiver Interface 215 Transceiver 216 User Interface 217 Satellite Positioning System (SPS) Receiver 218 Camera 219 Positioning (Motion) Devices 220 Bus 230 General Purpose / Application Processor 231 Digital Signal Processor (DSP) 232 Modem Processor 233 Video Processor 234 Sensor Processor 240 Wireless Transceiver 242 Transmitter 244 Receiver 246 Antenna 248 Wireless Signal 250 Wired Transceiver 252 Transmitter 254 Receiver 260 SPS signal 262 SPS Antenna 270 Inertial Measurement Unit (IMU) 271 Magnetometer 272 Environmental Sensor 273 Accelerometer 274 Gyroscope 300 Access Points (AP) 310 Processor 311 Memory 312 Software (SW) 315 Transceiver 317 SPS Receiver 320 Bus 340 Wireless Transceiver 342 Transmitter 344 Receiver 346 Antenna 348 Wireless Signal 350 Wired Transceiver 352 Transmitter 354 Receiver 360 SPS signal 362 SPS Antenna 402 Transmitting Antenna 404 Receiving Antenna 406 Digital to Analog Converter (DAC) 408 Transmitting RF Module 410 Transmission Leakage Signal 412a RF signal 412b reflected signal 414 Analog-to-Digital Converter (ADC) 416 Receiver RF Module 418 Target 420 Receive Chain 422 receive chain 502 Relative Power Axis 504 Timeline 506 Signal Response Function 508 First Peak 510 Second Peak 602 Transceiver 604 1st Transceiver Chain 606a Transceiver Chain 606b Transceiver Chain 608a RF signal 608b RF signal 608c reflected signal 608d reflected signal 610 Target 700 methods 800 ways 900 ways 1000 ways

Claims

1. 1. A method for determining distance to an object using radio frequency sensing, comprising: transmitting a radio frequency signal using a transmission channel on a wireless device, the radio frequency signal being a pre-designated sequence transmitted n times; receiving a leakage signal using a receive channel on the wireless device at a first time, the leakage signal being based on the radio frequency signal; receiving, at a second time, a reflected signal using the receive channel on the wireless device, the reflected signal being based on the radio frequency signal reflecting off the object, the reflected signal being of at least one pre-specified sequence; determining the distance to the object based at least in part on a difference between the first time and the second time; The method includes:

2. The method of claim 1, wherein n is greater than 1, the reflected signal is a received sequence of m, and m is less than or equal to n.

3. The method of claim 2 , wherein the pre-designated sequence is a single-carrier Zadoff-Chu sequence.

4. The method of claim 2 , wherein the pre-designated sequence includes orthogonal frequency division multiplexing symbols.

5. The method of claim 2 , wherein the pre-specified sequence comprises one or more Wi-Fi packets.

6. The method of claim 1 , further comprising the steps of transmitting a plurality of radio frequency signals and receiving one or more of the plurality of radio frequency signals.

7. The method of claim 1 , further comprising transmitting a plurality of radio frequency signals using a plurality of transmission channels.

8. The method of claim 1 , wherein receiving the radio frequency signal comprises receiving the radio frequency signal with multiple receive chains.

9. The method of claim 8 further comprising determining an angle of arrival of the received radio frequency signal.

10. The method of claim 1 , further comprising determining an angle of departure of the radio frequency signal.

11. The method of claim 1 , wherein the steps of transmitting the radio frequency signal and receiving the radio frequency signal are performed using single-chain transmit and receive operations.

12. The method of claim 2, further comprising the step of combining the m received sequences to increase a signal-to-noise ratio (SNR) of the reflected signal.

13. 1. An apparatus comprising: Memory, at least one transceiver including at least one transmit chain and at least one receive chain; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor comprising: transmitting a radio frequency signal using the at least one transmit chain, the radio frequency signal being a pre-designated sequence transmitted n times; receiving a leakage signal with the at least one receive chain at a first time, the leakage signal being based on the radio frequency signal; receiving a reflected signal with the at least one receive chain at a second time, the reflected signal being based on the radio frequency signal reflecting off an object, the reflected signal being of at least one pre-designated sequence; determining a distance to the object based at least in part on a difference between the first time and the second time; and configured to: Device.

14. The apparatus of claim 13, wherein the processor is further configured to perform the method of any one of claims 2 to 12.

15. A non-transitory processor-readable storage medium comprising processor-readable instructions for causing one or more processors to perform the method of any one of claims 1 to 12.

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