Positioning of passive devices based on differential carrier phase estimation at harmonic frequencies

Abstract

Systems, apparatus, processes, and computer-readable media for wireless communication are disclosed. In some aspects, a network device can receive a signal including a reflected signal reflected from a passive network device and one or more interfering signals. The network device can determine a propagation delay based on a differential carrier phase estimate at a harmonic frequency of a received signal in the frequency domain. The network device can determine a location of the passive network device using the propagation delay. In some cases, the network device can transmit a source signal to the passive network device, in which case the reflected signal can be generated by reflection of the source signal from the passive network device.

Description

Technical Field

[0001] The present disclosure generally relates to processing sensing signals for positioning. For example, aspects of the present disclosure relate to systems and techniques for performing positioning of passive devices (e.g., passive Internet of Things (IoT) devices, radio frequency identification (RFID) devices, etc.) based on differential carrier phase estimation at harmonic frequencies. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, and broadcast. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems (such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems) and fifth generation (5G) systems (which may be referred to as new radio (NR) systems). These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each base station or network access node simultaneously supporting communication for multiple communication devices, which may be further referred to as user equipment (UE). Some wireless communication systems may support communication between UEs, which may involve direct transmission between two or more UEs. Wireless communication systems may also support sensing for positioning to determine or estimate one or more characteristics of a target object, such as its distance, position, angle, and / or velocity. Target objects may include UEs, vehicles, obstacles, users, buildings, or other objects. Interference signals received by the wireless communication system during positioning may reduce positioning accuracy. Improved positioning techniques are needed to mitigate the effects of received interference signals. Summary of the Invention

[0003] The following presents a simplified summary of one or more aspects disclosed herein. Therefore, the following summary should neither be considered an exhaustive overview of all contemplated aspects nor be considered to identify key or critical elements related to all contemplated aspects or to delineate the scope associated with any particular aspect. Therefore, the sole purpose of the following summary is to present certain concepts related to one or more aspects of the mechanisms disclosed herein in a simplified form prior to the detailed description presented below.

[0004] Systems and techniques are described for providing a solution for performing location determination of passive devices based on differential carrier phase estimation at harmonic frequencies. According to at least one illustrative example, a network device for wireless communication is provided. The network device includes: at least one memory; and at least one processor coupled to the at least one memory and configured to: receive a signal including a reflected signal reflected from a passive network device and one or more interfering signals; determine a propagation delay based on differential carrier phase estimation at harmonic frequencies of the received signal in the frequency domain; and determine a location of the passive network device using the propagation delay.

[0005] In another illustrative example, a method for wireless communication at a network device is provided. The method includes: receiving, by the network device, a signal including a reflected signal reflected from a passive network device and one or more interfering signals; determining, by the network device, a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and determining, by the network device, a location of the passive network device using the propagation delay.

[0006] In another illustrative example, a non-transitory computer-readable medium having instructions stored thereon is provided that, when executed by at least one processor, causes the at least one processor to: receive a signal including a reflected signal reflected from a passive network device and one or more interfering signals; determine a propagation delay based on a differential carrier phase estimate at harmonic frequencies of the received signal in a frequency domain; and determine a location of the passive network device using the propagation delay.

[0007] In another illustrative example, a network device for wireless communication is provided. The network device includes: means for receiving a signal including a reflected signal reflected from a passive network device and one or more interfering signals; means for determining a propagation delay based on a differential carrier phase estimate at harmonic frequencies of the received signal in the frequency domain; and means for determining a location of the passive network device using the propagation delay.

[0008] In another illustrative example, a network device for wireless communication is provided. The network device includes at least one memory; and at least one processor coupled to the at least one memory and configured to: send a source signal to a passive network device; receive a signal including a reflected signal and one or more interfering signals, wherein the reflected signal is generated by the source signal reflecting from the passive network device; determine a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and determine a location of the passive network device using the propagation delay.

[0009] In another illustrative example, a method for wireless communication at a network device is provided. The method includes: transmitting, by the network device, a source signal to a passive network device; receiving, by the network device, a signal comprising a reflected signal and one or more interference signals, wherein the reflected signal is generated by reflection of the source signal from the passive network device; determining, by the network device, a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and determining, by the network device, a location of the passive network device using the propagation delay.

[0010] In another illustrative example, a non-transitory computer-readable medium having instructions stored thereon is provided, the instructions, when executed by at least one processor, causing the at least one processor to: send a source signal to a passive network device; receive a signal including a reflected signal and one or more interfering signals, wherein the reflected signal is generated by the source signal being reflected from the passive network device; determine a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in a frequency domain; and determine a location of the passive network device using the propagation delay.

[0011] In another illustrative example, a network device for wireless communication is provided. The network device includes: means for transmitting a source signal to a passive network device; means for receiving a signal including a reflected signal and one or more interfering signals, wherein the reflected signal is generated by reflection of the source signal from the passive network device; means for determining a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and means for determining a location of the passive network device using the propagation delay.

[0012] In some aspects, one or more of the devices described herein are UEs, are part of UEs, and / or include UEs, such as wearable devices, extended reality (XR) devices (e.g., virtual reality (VR) devices, augmented reality (AR) devices, or mixed reality (MR) devices), head-mounted display (HMD) devices, wireless communication devices, mobile devices (e.g., mobile phones and / or mobile handsets and / or so-called "smart phones" or other mobile devices), cameras, personal computers, laptop computers, server computers, vehicles or computing devices or components of vehicles, another device, or a combination thereof. In some aspects, the device includes one or more cameras for capturing one or more images. In some aspects, the device also includes a display for displaying one or more images, notifications, and / or other displayable data. In some aspects, the devices described above may include one or more sensors (e.g., one or more inertial measurement units (IMUs), such as one or more gyroscopes, one or more gyrometers, one or more accelerometers, any combination thereof, and / or other sensors).

[0013] This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. This subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all of the drawings, and each claim.

[0014] The foregoing and other features and aspects will become more apparent upon reference to the following description, claims and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are presented to aid in describing the various aspects of the present disclosure and are provided solely for illustration and not limitation of the various aspects.

[0016] Figure 1 is a diagram illustrating an example wireless communication system that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimates at harmonic frequencies in accordance with some aspects of the present disclosure.

[0017] Figure 2 is a diagram illustrating an example of a decomposed base station architecture that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimates at harmonic frequencies, in accordance with some aspects of the present disclosure.

[0018] Figure 3 is a diagram illustrating an example of a frame structure that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimates at harmonic frequencies, in accordance with some aspects of the present disclosure.

[0019] Figure 4 is a block diagram illustrating an example of a computing system of an electronic device that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimates at harmonic frequencies in accordance with some aspects of the present disclosure.

[0020] Figure 5 is a diagram illustrating an example of a wireless device utilizing radio frequency (RF) monostatic sensing techniques, according to some aspects of the present disclosure, that may be used by the disclosed systems and techniques described herein to determine one or more characteristics of a target object.

[0021] Figure 6 is a diagram illustrating an example of a receiver utilizing RF bistatic sensing techniques with one transmitter, according to some aspects of the present disclosure, which may be used by the disclosed systems and techniques described herein to determine one or more characteristics of a target object.

[0022] Figure 7is a diagram illustrating an example of a receiver utilizing RF bistatic sensing techniques with multiple transmitters, according to some aspects of the present disclosure, which may be used by the disclosed systems and techniques described herein to determine one or more characteristics of a target object.

[0023] Figure 8 is a diagram illustrating example geometries for bistatic (or monostatic) sensing according to some aspects of the present disclosure.

[0024] Figure 9 is a diagram illustrating bistatic distances for bistatic sensing according to some aspects of the present disclosure.

[0025] Figure 10 is a diagram illustrating an example of a system employing passive devices for communication according to some aspects of the present disclosure.

[0026] Figure 11 is an example of what can be done according to some aspects of the present disclosure Figure 10 Schematic diagram of examples of different signals sent and received within a system.

[0027] Figure 12A is a graph illustrating examples of different signals in the time domain according to some aspects of the present disclosure, which may be represented by Figure 10 The system sends and receives data to different network devices.

[0028] Figure 12B is a graph illustrating examples of different frequency spectra in the frequency domain according to some aspects of the present disclosure, corresponding to Figure 12A The graph of the signal.

[0029] Figure 13A is a diagram illustrating an example of a system for locating a passive device according to some aspects of the present disclosure, where the system is performing monostatic sensing for positioning.

[0030] Figure 13B is a diagram illustrating an example of a system for locating a passive device, wherein the system is performing bistatic sensing for positioning, according to some aspects of the present disclosure.

[0031] Figure 14A is a diagram illustrating examples of different signals that may be sent and received within a system performing monostatic sensing for locating passive devices, in accordance with some aspects of the present disclosure.

[0032] Figure 14B is a diagram illustrating examples of different signals that may be sent and received within a system performing bistatic sensing for locating passive devices, in accordance with some aspects of the present disclosure.

[0033] Figure 15is a diagram illustrating examples of different signals in the time domain that may be sent and received by different network devices of a system for locating passive devices based on differential carrier phase estimation at harmonic frequencies, according to some aspects of the present disclosure.

[0034] Figure 16 is a diagram illustrating examples of different signals in the time domain and corresponding spectra in the frequency domain that may be used to determine propagation delay by a system for locating passive devices based on differential carrier phase estimates at harmonic frequencies, according to some aspects of the present disclosure.

[0035] Figure 17 is a diagram illustrating examples of different signals in the time domain that may be used to determine reflection delay (group delay) by a system for locating passive devices based on differential carrier phase estimation at harmonic frequencies in accordance with aspects of the present disclosure.

[0036] Figure 18 is a flow chart illustrating an example of a process for wireless communication utilizing a method for locating passive devices based on differential carrier phase estimation at harmonic frequencies in accordance with some aspects of the present disclosure.

[0037] Figure 19 is a flow chart illustrating an example of a process for wireless communication utilizing a method for locating passive devices based on differential carrier phase estimation at harmonic frequencies in accordance with some aspects of the present disclosure.

[0038] Figure 20 is a block diagram illustrating an example of a computing system that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimates at harmonic frequencies, in accordance with some aspects of the present disclosure. DETAILED DESCRIPTION

[0039] For illustrative purposes, certain aspects of the present disclosure are provided below. Without departing from the scope of the present disclosure, alternative aspects can be designed. Additionally, well-known elements of the present disclosure will not be described in detail or will be omitted to avoid making the relevant details of the present disclosure difficult to understand. Some aspects described herein can be applied independently, and some of them can be applied in combination, which is obvious to those skilled in the art. In the following description, specific details are set forth for explanation purposes to provide a thorough understanding of various aspects of the application. However, it will be apparent that various aspects can be implemented without these specific details. Each drawing and description is not intended to be restrictive.

[0040] The following description provides only exemplary aspects and is not intended to limit the scope, applicability, or configuration of the present disclosure. Instead, the following description of the exemplary aspects will provide those skilled in the art with a description that can be used to implement the exemplary aspects. It should be understood that various changes may be made to the function and arrangement of the elements without departing from the scope of the present application as set forth in the appended claims.

[0041] Radar sensing systems use radio frequency (RF) waveforms to perform RF sensing to determine or estimate one or more characteristics of a target object, such as the distance, angle, and / or velocity of the target object. The target object may include a vehicle, an obstacle, a user, a building, or other objects. A typical radar system includes at least one transmitter, at least one receiver, and at least one processor. When a single receiver is co-located with the transmitter, the radar sensing system can perform single-station sensing. When a single receiver of a first device is positioned away from the transmitter of a second device, the radar system can perform dual-station sensing. Similarly, when multiple receivers of multiple devices are positioned away from at least one transmitter of at least one device, the radar system can perform multi-station sensing.

[0042] During operation of a radar sensing system, a transmitter transmits an electromagnetic (EM) signal in the RF domain toward a target object. The signal reflects from the target object to produce one or more reflected signals that provide information or properties about the target, such as the position and velocity of the target object. At least one receiver receives the one or more reflected signals, and at least one processor, which may be associated with the at least one receiver, utilizes information from the one or more reflected signals to determine information or properties of the target object. The target object may also be referred to herein as a target.

[0043] Generally speaking, RF sensing involves monitoring moving targets with different motions (e.g., moving cars or pedestrians, human body motions such as breathing, and / or other micro-motions associated with the target). Doppler, which measures phase changes in the signal and indicates motion, is an important characteristic for sensing targets.

[0044] In some cases, radar sensing signals, which may be referred to as radar reference signals (RS), such as sensing reference signals (S-RS), may be designed and used for sensing purposes. Radar RSs do not contain any communication information. In contrast, communication RSs, such as demodulation reference signals (DMRSs), are typically designed and used only for communication purposes, such as estimating channel parameters for communication.

[0045] Cellular communication systems are designed to transmit communication signals in designated communication frequency bands (e.g., 23 gigahertz (GHz), 3.5 GHz, etc. for 5G / NR, 2.2 GHz, etc. for LTE). RF sensing systems are designed to transmit RF sensing signals in designated radar RF frequency bands (e.g., 77 GHz for autonomous driving). In future cellular communication systems, it is likely that the spectrum used for communication and sensing will be shared. In this case, communication and sensing should be considered jointly.

[0046] Passive devices have recently been introduced into wireless communication (e.g., 5G and sixth generation (6G) wireless communication) systems to reduce the cost of IoT devices and achieve zero-power green communication. Passive devices (e.g., network devices) may be referred to as passive UEs (pUEs), tags, environmental backscatter devices, or backscatter devices. Passive devices may include passive Internet of Things (IoT) devices, radio frequency identification (RFID) devices, or other devices. Passive devices typically do not have batteries (or have limited batteries) in their terminals and rely on energy harvesting to power them. In order to collect energy, passive devices can accumulate energy from received radio signaling in their terminals, and in some cases, can also accumulate energy from solar energy in their terminals as a supplement. Passive devices typically do not contain radio wave (e.g., RF waveform) transmission circuitry, so passive devices can only output data (e.g., can only send information) by reflecting received radio waves. Key requirements for passive devices may typically include, but are not limited to, a coverage range of thirty meters (e.g., to build viable wireless network coverage in buildings up to 5,000 square meters in size, such as warehouses), power consumption of less than 0.1 milliwatts (mW) to support operation without batteries, a cost of less than $0.02 to meet cost-sensitive applications, and / or ninety percent (90%) positioning accuracy within a distance of three to five meters (e.g., in both horizontal and vertical directions).

[0047] Passive devices may have multiple applicable use cases, which may include but are not limited to being used as industrial sensors where battery replacement is extremely difficult or undesirable (e.g., for safety monitoring or fault detection in smart factories, infrastructure, or environments); being used in smart logistics / warehousing due to their extremely low cost, small size, maintenance-free, durable, and long life (e.g., for automated asset management in factories to replace radio frequency identification (RFID) tags); being used for household item management within smart home networks; being adopted in wearable devices (e.g., wearable devices for medical monitoring of patients where the patients do not need to replace the batteries themselves); and / or being used for environmental monitoring.

[0048] Passive devices can be used for both communication and sensing (e.g., positioning). For example, during communication operations, an RF source (e.g., a base station (such as a gNodeB (gNB)) or a UE) can transmit an RF source waveform (e.g., an energy-harvesting radio wave) to a passive device (e.g., a tag or sensor). After the passive device receives the RF source waveform, the passive device can accumulate energy from the RF source waveform within a terminal of the passive device. After the passive device has accumulated a sufficient amount of energy from the RF source waveform, the passive device can begin reflecting (e.g., radiating) the RF source waveform radiated onto the passive device. The reflection of the RF source waveform by the passive device can follow a specific on / off pattern. The on / off pattern can be based on control information (e.g., information bits) within a synchronization signal (SS) or a control signal previously received by the passive device. A reader (e.g., a UE or gNB) can then detect the reflection pattern of the reflected RF source waveform and obtain backscattered communication data from the reflected RF source waveform.

[0049] Passive devices can be sensed (e.g., located) using monostatic sensing, bistatic sensing, or both. For monostatic sensing, the RF source and reader can be co-located (e.g., both implemented within a network device (such as a UE or gNB)). For example, during monostatic sensing of a passive device (e.g., a pUE), a network device (e.g., a UE or gNB) operating as an RF source (e.g., a transmitter) can transmit an RF source waveform to the passive device. The passive device can reflect the RF source waveform to produce a reflected RF source waveform that can propagate in a direction back toward the network device. The network device operating as a reader (e.g., a receiver) can receive the reflected RF source waveform and then perform positioning processing using the reflected RF source waveform to locate the passive device.

[0050] For bistatic sensing, the RF source (e.g., a gNB or UE) and the reader (e.g., a UE or gNB) can be separated from each other. For example, during bistatic sensing of a passive device (e.g., a pUE), the RF source (e.g., a gNB or UE) can transmit an RF source waveform to the passive device. The passive device can reflect the RF source waveform to generate a reflected RF source waveform, which can propagate toward the reader (e.g., a UE or gNB). The reader can receive the reflected RF source waveform and then perform positioning processing using the reflected RF source waveform to locate the passive device.

[0051] When locating passive devices using monostatic or bistatic sensing, the received signal at the reader (e.g., gNB or UE) may consist not only of the passive device's reflected signal, but also of interfering signals. These interfering signals may include directional (e.g., line-of-sight (LOS)) signals (e.g., for bistatic sensing only) and / or background reflected (e.g., non-line-of-sight (NLOS)) signals. Because the passive device's reflected signal is typically weaker than the combined signal strength of these interfering signals (e.g., the directional signal plus the background reflected signal), it may be difficult for the reader to fully mitigate the effects of these interfering signals in the time domain. Consequently, due to the effects of these interfering signals in the time domain, it may be challenging for the reader to measure the delay of the passive device's reflected signal and the distance between the passive device and the reader.

[0052] In some aspects of the present disclosure, systems, apparatuses, methods (also referred to as processes), and computer-readable media (collectively referred to herein as "systems and techniques") are described herein that provide a solution for locating passive devices (e.g., pUEs) based on differential carrier phase estimates at harmonic frequencies. Specifically, the systems and techniques allow for locating passive devices by using differential carrier phase estimates at harmonic frequencies to completely mitigate interference (e.g., directional propagation signals plus background reflection signals).

[0053] In one or more aspects, for example, during operation of a system and technique for locating a passive device (e.g., a pUE), an RF source (e.g., a gNB or UE) may transmit a synchronization signal (or control channel or signal) and a duration of a narrowband RF source waveform (e.g., a sine wave) to the passive device. The passive device may monitor the synchronization signal (or control channel or signal) and may synchronize itself (e.g., synchronize a reflection switch of the passive device) according to a synchronization schedule within the synchronization signal (or control channel or signal) (e.g., specified within information bits). After the passive device has synchronized itself according to the synchronization schedule, the passive device may periodically turn on and off its reflection of the received RF source waveform according to the synchronization schedule. After a reader receives the reflected signal, the reader may estimate an "RF source to pUE to reader" propagation delay based on a differential carrier phase estimate at a harmonic frequency.

[0054] Additional aspects of the disclosure are described in more detail below.

[0055] As used herein, the terms "user equipment" (UE) and "network entity" are not intended to be exclusive to or otherwise limited to any particular radio access technology (RAT), unless otherwise specified. In general, a UE can be any wireless communication device (e.g., a mobile phone, a router, a tablet, a laptop, and / or a tracking device, etc.), a wearable device (e.g., a smart watch, smart glasses, a wearable ring, and / or an extended reality (XR) device (such as a virtual reality (VR) headset, an augmented reality (AR) headset or glasses, or a mixed reality (MR) headset)), a vehicle (e.g., a car, a motorcycle, a bicycle, etc.), and / or an Internet of Things (IoT) device, etc., for a user to communicate on a wireless communication network. A UE can be mobile or can be stationary (e.g., at certain times) and can communicate with a radio access network (RAN). As used herein, the term "UE" may be interchangeably referred to as an "access terminal" or "AT," a "client device," a "wireless device," a "subscriber device," a "subscriber terminal," a "subscriber station," a "user terminal" or "UT," a "mobile device," a "mobile terminal," a "mobile station," or variations thereof. Generally speaking, a UE may communicate with a core network via a RAN, and through the core network, the UE may connect to external networks such as the Internet and to other UEs. Of course, other mechanisms for connecting to the core network and / or the Internet are also possible for the UE, such as through a wired access network, a wireless local area network (WLAN) network (e.g., based on IEEE 802.11 communication standards, etc.), and the like.

[0056] The network entity may be implemented in a converged or monolithic base station architecture, or alternatively, in a disaggregated base station architecture, and may include one or more of a central unit (CU), a distributed unit (DU), a radio unit (RU), a near real-time (near-RT) RAN intelligent controller (RIC), or a non-real-time (non-RT) RIC. A base station (e.g., having a converged / monolithic base station architecture or a disaggregated base station architecture) may operate according to one of several RATs for communicating with UEs (depending on the network in which it is deployed) and may be alternatively referred to as an access point (AP), a network node, a NodeB (NB), an evolved NodeB (eNB), a next-generation eNB (ng-eNB), a new radio (NR) NodeB (also referred to as a gNB or gNodeB), etc. A base station may primarily support radio access for UEs, including supporting data, voice, and / or signaling connections for the supported UEs. In some systems, a base station may provide edge node signaling functionality, while in other systems, a base station may provide additional control and / or network management functionality. The communication link by which a UE can transmit signals to a base station is called an uplink (UL) channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). The communication link by which a base station can transmit signals to a UE is called a downlink (DL) or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, or a forward traffic channel, etc.). As used herein, the term traffic channel (TCH) can refer to an uplink, a reverse or downlink, and / or a forward traffic channel.

[0057] The term "network entity" or "base station" (e.g., having an aggregated / monolithic base station architecture or a disaggregated base station architecture) may refer to a single physical transmit-receive point (TRP) or multiple physical transmit-receive points (TRPs), which may or may not be co-located. For example, where the term "network entity" or "base station" refers to a single physical TRP, the physical TRP may be a base station antenna corresponding to a cell (or several cell sectors) of the base station. Where the term "network entity" or "base station" refers to multiple co-located physical TRPs, these physical TRPs may be antenna arrays of the base station (e.g., as in a multiple-input multiple-output (MIMO) system or where the base station employs beamforming). Where the term "base station" refers to multiple non-co-located physical TRPs, the physical TRPs may be a distributed antenna system (DAS) (a network of spatially separated antennas connected to a common source via a transmission medium) or a remote radio head (RRH) (a remote base station connected to a serving base station). Alternatively, the non-co-located physical TRPs may be the serving base station receiving the measurement report from the UE and the neighbor base station whose reference radio frequency (RF) signal (or simply "reference signal") the UE is measuring. Because, as used herein, a TRP is the point through which a base station transmits and receives wireless signals, references to transmitting from or receiving at a base station should be understood to refer to the specific TRP of a base station.

[0058] In some specific implementations of supporting UE positioning, a network entity or base station may not support wireless access for the UE (e.g., may not support data, voice, and / or signaling connections for the UE), but may instead send a reference signal to the UE to be measured by the UE and / or may receive and measure signals sent by the UE. Such a base station may be referred to as a positioning beacon (e.g., when sending a signal to the UE) and / or as a position measurement unit (e.g., when receiving and measuring a signal from the UE).

[0059] RF signals consist of electromagnetic waves of a given frequency that transmit information through the space between a transmitter and a receiver. As used herein, a transmitter may transmit a single "RF signal" or multiple "RF signals" to a receiver. However, due to the propagation characteristics of RF signals through multipath channels, a receiver may receive multiple "RF signals" corresponding to each transmitted RF signal. The same transmitted RF signal on different paths between the transmitter and receiver may be referred to as a "multipath" RF signal. As used herein, an RF signal may also be referred to as a "wireless signal" or simply as a "signal" when the context clearly indicates that the term "signal" refers to either a wireless signal or an RF signal.

[0060] According to various aspects, Figure 1An exemplary wireless communication system 100 that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimation at harmonic frequencies described herein is illustrated. The wireless communication system 100, which may also be referred to as a wireless wide area network (WWAN), may include various base stations 102 and various UEs 104. In some aspects, the base stations 102 may also be referred to as "network entities" or "network nodes." One or more of the base stations 102 may be implemented in a converged or monolithic base station architecture. Additionally or alternatively, one or more of the base stations 102 may be implemented in a disaggregated base station architecture and may include one or more of a central unit (CU), a distributed unit (DU), a radio unit (RU), a near real-time (near-RT) RAN intelligent controller (RIC), or a non-real-time (non-RT) RIC. The base stations 102 may include macrocell base stations (high-power cellular base stations) and / or small cell base stations (low-power cellular base stations). In one aspect, the macro cell base station may include an eNB and / or an ng-eNB (where the wireless communication system 100 corresponds to a long term evolution (LTE) network), or a gNB (where the wireless communication system 100 corresponds to an NR network), or a combination of both, and the small cell base station may include a femto cell, a pico cell, a micro cell, etc.

[0061] The base stations 102 may collectively form a RAN and interface with a core network 170 (e.g., an evolved packet core (EPC) or a 5G core (5GC)) via backhaul links 122, and may interface with one or more location servers 172 (which may be part of the core network 170 or external to the core network 170) via the core network 170. Among other functions, the base stations 102 may perform functions related to one or more of: delivering user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via the EPC or 5GC) via backhaul links 134 (which may be wired and / or wireless).

[0062] Base stations 102 can communicate wirelessly with UEs 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. In one aspect, base stations 102 in each coverage area 110 can support one or more cells. A "cell" is a logical communication entity used to communicate with a base station (e.g., on a certain frequency resource, referred to as a carrier frequency, component carrier, carrier, frequency band, etc.) and can be associated with an identifier (e.g., a physical cell identifier (PCI), a virtual cell identifier (VCI), a cell global identifier (CGI)) to distinguish between cells operating on the same or different carrier frequencies. In some cases, different cells can be configured according to different protocol types (e.g., machine type communication (MTC), narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or other protocol types) that can provide access to different types of UEs. Because a cell is supported by a specific base station, the term "cell" can refer to either or both of the logical communication entity and the base station supporting the logical communication entity, depending on the context. Furthermore, since a TRP is generally the physical transmission point of a cell, the terms "cell" and "TRP" can be used interchangeably. In some cases, the term "cell" may also refer to a geographic coverage area (eg, a sector) of a base station, so long as a carrier frequency can be detected and used for communications within some portion of the geographic coverage area 110.

[0063] Although the geographic coverage areas 110 of adjacent macrocell base stations 102 may partially overlap (e.g., in a handover area), some areas of the geographic coverage areas 110 may substantially overlap with the larger geographic coverage area 110. For example, a small cell base station 102' may have a coverage area 110' that substantially overlaps with the coverage areas 110 of one or more macrocell base stations 102. A network that includes both small cell base stations and macrocell base stations may be referred to as a heterogeneous network. A heterogeneous network may also include a Home eNB (HeNB), which may provide service to a restricted group known as a Closed Subscriber Group (CSG).

[0064] The communication link 120 between the base station 102 and the UE 104 may include uplink (also referred to as a reverse link) transmissions from the UE 104 to the base station 102 and / or downlink (also referred to as a forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may utilize MIMO antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link 120 may be over one or more carrier frequencies. The allocation of carriers may be asymmetric for the downlink and uplink (e.g., more or fewer carriers may be allocated to the downlink than to the uplink).

[0065] The wireless communication system 100 may further include a WLAN AP 150 in communication with a WLAN station (STA) 152 via a communication link 154 in an unlicensed spectrum (e.g., 5 gigahertz (GHz)). When communicating in the unlicensed spectrum, the WLAN STA 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) or a listen-before-talk (LBT) procedure before communicating to determine whether the channel is available. In some examples, the wireless communication system 100 may include devices (e.g., UEs, etc.) that communicate with one or more UEs 104, base stations 102, APs 150, etc. using an ultra-wideband (UWB) spectrum. The UWB spectrum may range from 3.1 GHz to 10.5 GHz.

[0066] The small cell base station 102' can operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell base station 102' can adopt LTE or NR technology and use the same 5 GHz unlicensed spectrum used by the WLAN AP 150. The small cell base station 102' using LTE and / or 5G in the unlicensed spectrum can boost the coverage of the access network and / or increase the capacity of the access network. NR in the unlicensed spectrum can be referred to as NR-U. LTE in the unlicensed spectrum can be referred to as LTE-U, License Assisted Access (LAA), or MulteFire.

[0067] The wireless communication system 100 may also include a millimeter wave (mmW) base station 180 that can operate at mmW frequencies and / or near-mmW frequencies to communicate with the UE 182. The mmW base station 180 can be implemented in a converged or monolithic base station architecture, or alternatively, in a disaggregated base station architecture (e.g., including one or more of a CU, DU, RU, near-RT RIC, or non-RT RIC). Extremely high frequency (EHF) is a portion of the RF band in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz, with wavelengths between 1 mm and 10 mm. Radio waves in this band may be referred to as millimeter waves. Near-mmW can extend down to frequencies of 3 GHz with wavelengths of 100 mm. Super high frequency (SHF) bands extend between 3 GHz and 30 GHz and are also referred to as centimeter waves. Communications using mmW and / or near-mmW radio frequency bands have high path loss and relatively short range. The mmW base station 180 and the UE 182 can utilize beamforming (transmit and / or receive) on the mmW communication link 184 to compensate for the extremely high path loss and short distance. In addition, it should be understood that in alternative configurations, one or more base stations 102 can also use mmW or near-mmW and beamforming for transmission. Therefore, it should be understood that the foregoing illustrations are merely examples and should not be construed as limiting the various aspects disclosed herein.

[0068] Transmit beamforming is a technique for focusing an RF signal in a specific direction. Traditionally, when a network node or entity (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omnidirectionally). With transmit beamforming, the network node determines where a given target device (e.g., a UE) is located (relative to the transmitting network node) and projects a stronger downlink RF signal in that specific direction, thereby providing the receiving device with a faster and stronger RF signal (in terms of data rate). To change the directionality of the RF signal when transmitting, the network node can control the phase and relative amplitude of the RF signal at each of the one or more transmitters broadcasting the RF signal. For example, the network node can use an array of antennas (referred to as a "phased array" or "antenna array") that form RF beams that can be "steered" to point in different directions without actually moving the antennas. Specifically, the RF currents from the transmitters are fed to the individual antennas in the correct phase relationship so that the radio waves from the individual antennas add together in the desired direction to increase radiation, and cancel out in undesired directions to suppress radiation.

[0069] The transmit beams can be quasi-colocated, meaning that they have the same parameters for a receiver (e.g., a UE) regardless of whether the network node's transmit antennas themselves are physically co-located. In NR, there are four types of quasi-colocated (QCL) relationships. Specifically, a given type of QCL relationship means that certain parameters about the second reference RF signal on the second beam can be derived based on information about the source reference RF signal on the source beam. Thus, if the source reference RF signal is QCL type A, the receiver can use the source reference RF signal to estimate the Doppler shift, Doppler spread, average delay, and delay spread of the second reference RF signal sent on the same channel. If the source reference RF signal is QCL type B, the receiver can use the source reference RF signal to estimate the Doppler shift and Doppler spread of the second reference RF signal sent on the same channel. If the source reference RF signal is QCL type C, the receiver can use the source reference RF signal to estimate the Doppler shift and average delay of the second reference RF signal sent on the same channel. If the source reference RF signal is QCL type D, the receiver may use the source reference RF signal to estimate spatial reception parameters of a second reference RF signal transmitted on the same channel.

[0070] In receive beamforming, a receiver uses receive beams to amplify RF signals detected on a given channel. For example, a receiver may increase the gain setting of an antenna array in a particular direction and / or adjust the phase setting of an antenna array in a particular direction to amplify (e.g., increase the gain level of) RF signals received from that direction. Thus, when a receiver is said to be beamforming in a certain direction, it means that the beam gain in that direction is high relative to the beam gain in other directions, or that the beam gain in that direction is the highest compared to the beam gains of other beams available to the receiver. This results in a stronger received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal to interference plus noise ratio (SINR), etc.) for RF signals received from that direction.

[0071] The receive beams may be spatially correlated. The spatial relationship means that the parameters for the transmit beam for the second reference signal may be derived based on information about the receive beam for the first reference signal. For example, a UE may receive one or more reference downlink reference signals (e.g., positioning reference signal (PRS), tracking reference signal (TRS), phase tracking reference signal (PTRS), cell-specific reference signal (CRS), channel state information reference signal (CSI-RS), primary synchronization signal (PSS), secondary synchronization signal (SSS), synchronization signal block (SSB), etc.) from a network node or entity (e.g., a base station) using a specific receive beam. The UE may then form a transmit beam based on the parameters of the receive beam for transmitting one or more uplink reference signals (e.g., uplink positioning reference signal (UL-PRS), sounding reference signal (SRS), demodulation reference signal (DMRS), PTRS, etc.) to the network node or entity (e.g., a base station).

[0072] Note that depending on the entity forming the "downlink" beam, the beam can be a transmit beam or a receive beam. For example, if a network node or entity (e.g., a base station) is forming a downlink beam to send a reference signal to a UE, the downlink beam is a transmit beam. However, if the UE is forming a downlink beam, the downlink beam is a receive beam that receives a downlink reference signal. Similarly, depending on the entity forming the "uplink" beam, the beam can be a transmit beam or a receive beam. For example, if a network node or entity (e.g., a base station) is forming an uplink beam, the uplink beam is an uplink receive beam, while if the UE is forming an uplink beam, the uplink beam is an uplink transmit beam.

[0073] In 5G, the spectrum in which wireless network nodes or entities (e.g., base stations 102 / 180, UEs 104 / 182) operate is divided into multiple frequency ranges: FR1 (from 450 megahertz (MHz) to 6000 MHz), FR2 (from 24250 MHz to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). In multi-carrier systems such as 5G, one of the carrier frequencies is referred to as the "primary carrier" or "anchor carrier" or "primary serving cell" or "PCell," and the remaining carrier frequencies are referred to as "secondary carriers" or "secondary serving cells" or "SCells." In carrier aggregation, the anchor carrier is a carrier operating on the primary frequency (e.g., FR1) used by the UE 104 / 182 and the cell in which the UE 104 / 182 performs an initial radio resource control (RRC) connection establishment procedure or initiates an RRC connection reestablishment procedure. The primary carrier carries all common and UE-specific control channels and can be a carrier in a licensed frequency (however, this is not always the case). A secondary carrier is a carrier operating on a second frequency (e.g., FR2) that can be configured and used to provide additional radio resources once an RRC connection is established between the UE 104 and the anchor carrier. In some cases, the secondary carrier can be a carrier in an unlicensed frequency. The secondary carrier can contain only necessary signaling information and signals. For example, since the primary uplink carrier and the primary downlink carrier are typically UE-specific, those UE-specific signaling information and signals may not be present in the secondary carrier. This means that different UEs 104 / 182 in a cell can have different downlink primary carriers. The same is true for the uplink primary carrier. The network can change the primary carrier for any UE 104 / 182 at any time. This is done, for example, to balance the load on different carriers. Since a "serving cell" (whether a PCell or SCell) corresponds to the carrier frequency or component carrier that some base station is using to communicate, the terms "cell," "serving cell," "component carrier," "carrier frequency," etc. may be used interchangeably.

[0074] For example, still referring to Figure 1, one of the frequencies used by the macrocell base station 102 may be an anchor carrier (or "PCell"), and the other frequencies used by the macrocell base station 102 and / or the mmW base station 180 may be secondary carriers ("SCells"). In carrier aggregation, the base station 102 and / or the UE 104 may use spectrum with a bandwidth of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz) per carrier, with up to a total of Yx MHz (x component carriers) in each direction for transmission. The component carriers may or may not be spectrally adjacent to each other. The allocation of carriers may be asymmetric with respect to the downlink and uplink (e.g., more or fewer carriers may be allocated to the downlink than to the uplink). Simultaneous transmission and / or reception of multiple carriers enables the UE 104 / 182 to significantly increase its data transmission and / or reception rate. For example, two 20 MHz aggregated carriers in a multi-carrier system would theoretically result in a doubled data rate (i.e., 40 MHz) compared to the data rate achieved with a single 20 MHz carrier.

[0075] In order to operate on multiple carrier frequencies, the base station 102 and / or the UE 104 are equipped with multiple receivers and / or transmitters. For example, the UE 104 may have two receivers, namely "receiver 1" and "receiver 2," where "receiver 1" is a multi-band receiver that can be tuned to either frequency band (i.e., carrier frequency) "X" or frequency band "Y," while "receiver 2" is a single-band receiver that can be tuned to only frequency band "Z." In this example, if the UE 104 is being served in frequency band "X," frequency band "X" will be referred to as the PCell or active carrier frequency, and "receiver 1" will need to tune from frequency band "X" to frequency band "Y" (SCell) to measure frequency band "Y" (and vice versa). In contrast, regardless of whether the UE 104 is being served in frequency band "X" or frequency band "Y," due to the separate "receiver 2," the UE 104 can measure frequency band "Z" without interrupting service on frequency band "X" or frequency band "Y."

[0076] The wireless communication system 100 may further include a UE 164 that may communicate with the macrocell base station 102 over a communication link 120 and / or with the mmW base station 180 over a mmW communication link 184. For example, the macrocell base station 102 may support a PCell and one or more SCells for the UE 164, and the mmW base station 180 may support one or more SCells for the UE 164.

[0077] The wireless communication system 100 may also include one or more UEs, such as UE 190, that are indirectly connected to one or more communication networks via one or more device-to-device (D2D) or peer-to-peer (P2P) links (referred to as “side links”). Figure 1 In the example of FIG1 , UE 190 has a D2D P2P link 192 with one of UEs 104 connected to one of base stations 102 (e.g., UE 190 can indirectly obtain cellular connectivity through the D2D P2P link), and has a D2D P2P link 194 with WLAN STA 152 connected to WLAN AP 150 (UE 190 can indirectly obtain WLAN-based Internet connectivity through the D2D P2P link). In one example, D2D P2P links 192 and 194 can use any well-known D2D RAT (such as LTE Direct (LTE-D), Wi-Fi Direct (Wi-Fi-D), As mentioned above, UE 104 and UE 190 can be configured to communicate using sidelink communications. In some cases, the sidelink transmission may include a request for feedback from the receiving UE (e.g., hybrid automatic repeat request (HARQ)).

[0078] Figure 2 is a diagram illustrating an example of a disaggregated base station architecture that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimation at harmonic frequencies. A deployment of a communication system, such as a 5G NR system, may be arranged with various components or parts in a variety of ways. In a 5G NR system or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element, or network equipment, such as a base station (BS), or one or more units (or one or more components) that perform base station functions may be implemented in a converged or disaggregated architecture. For example, a BS, such as a NodeB (NB), an evolved NB (eNB), an NR BS, a 5G NB, an AP, a transmit receive point (TRP), or a cell, may be implemented as a converged base station (also referred to as a standalone BS or a monolithic BS) or a disaggregated base station.

[0079] A converged base station may be configured to utilize a radio protocol stack that is physically or logically integrated within a single RAN node. A decomposed base station may be configured to utilize a protocol stack that is physically or logically distributed across two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed across one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of the CU, DU, and RU may also be implemented as a virtual unit, namely a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0080] Base station type operation or network design can take into account the aggregated nature of base station functionality. For example, a disaggregated base station can be utilized in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (such as a network configuration initiated by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Disaggregation can include distributing functionality across two or more units at various physical locations, as well as virtually distributing functionality of at least one unit, which can enable flexibility in network design. Various units of a disaggregated base station or disaggregated RAN architecture can be configured for wired or wireless communication with at least one other unit.

[0081] As mentioned earlier, Figure 2 A diagram illustrating an example decomposed base station 201 architecture is shown. The decomposed base station 201 architecture may include one or more central units (CUs) 211, which may communicate directly with a core network 223 via a backhaul link, or indirectly with the core network 223 through one or more decomposed base station units, such as a near real-time (near-RT) RAN intelligent controller (RIC) 227 via an E2 link, or a non-real-time (non-RT) RIC 217 associated with a service management and orchestration (SMO) framework 207, or both. The CU 211 may communicate with one or more distributed units (DUs) 231 via corresponding midhaul links, such as an F1 interface. The DU 231 may communicate with one or more radio units (RUs) 241 via corresponding fronthaul links. The RU 241 may communicate with a corresponding UE 221 via one or more RF access links. In some implementations, a UE 221 may be served simultaneously by multiple RUs 241.

[0082] Each of these units (i.e., CU 211, DU 231, RU 241, as well as near-RT RIC 227, non-RT RIC 217, and SMO framework 207) may include or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller that provides instructions to the communication interface of these units, may be configured to communicate with one or more of the other units via the transmission medium. For example, these units may include a wired interface configured to receive or transmit signals to one or more of the other units via a wired transmission medium. Additionally, the units may include a wireless interface that may include a receiver, transmitter, or transceiver (such as an RF transceiver) configured to receive or transmit signals, or both, to one or more of the other units over a wireless transmission medium.

[0083] In some aspects, the CU 211 may host one or more higher layer control functions. Such control functions may include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by the CU 211. The CU 211 may be configured to handle user plane functionality (i.e., central unit-user plane (CU-UP)), control plane functionality (i.e., central unit-control plane (CU-CP)), or a combination thereof. In some specific implementations, the CU 211 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface (such as an E1 interface). As needed, the CU 211 may be implemented to communicate with the DU 231 for network control and signaling.

[0084] The DU 231 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 241. In some aspects, the DU 231 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more higher physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) based at least in part on a functional split, such as those defined by the 3rd Generation Partnership Project (3GPP). In some aspects, the DU 231 may also host one or more lower PHY layers. Each layer (or module) may be implemented using an interface configured to communicate signals with other layers (and modules) hosted by the DU 231 or with control functions hosted by the CU 211.

[0085] Lower layer functionality may be implemented by one or more RUs 241. In some deployments, a RU 241 controlled by a DU 231 may correspond to a logical node that hosts RF processing functionality or low PHY layer functionality (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, Physical Random Access Channel (PRACH) extraction and filtering, etc.), or both, based at least in part on a functional split (such as a lower layer functional split). In such an architecture, the RU 241 may be implemented to handle over-the-air (OTA) communications with one or more UEs 221. In some implementations, both real-time and non-real-time aspects of control plane communications and user plane communications with the RU 241 may be controlled by the corresponding DU 231. In some scenarios, this configuration may enable the implementation of the DU 231 and the CU 211 in a cloud-based RAN architecture (such as a vRAN architecture).

[0086] The SMO framework 207 can be configured to support RAN deployment and provisioning of both non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO framework 207 can be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which can be managed via an operations and maintenance interface (such as the O1 interface). For virtualized network elements, the SMO framework 207 can be configured to interact with a cloud computing platform (such as Open Cloud (O-Cloud) 291) to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface (such as the O2 interface). Such virtualized network elements may include, but are not limited to, CU 211, DU 231, RU 241, and near-RT RIC 227. In some implementations, the SMO framework 207 can communicate with hardware aspects of the 4G RAN (such as Open eNB (O-eNB) 213) via the O1 interface. Additionally, in some implementations, the SMO framework 207 can communicate directly with one or more RUs 241 via the O1 interface. The SMO framework 207 may also include a non-RT RIC 217 configured to support the functionality of the SMO framework 207 .

[0087] The non-RT RIC 217 may be configured to include logic that enables non-real-time control and optimization of RAN elements and resources, artificial intelligence / machine learning (AI / ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 227. The non-RT RIC 217 may be coupled to or in communication with the near-RT RIC 227 (e.g., via an A1 interface). The near-RT RIC 227 may be configured to include logic that enables near-real-time control and optimization of RAN elements and resources through data collection and actions over an interface (e.g., via an E2 interface) that connects one or more CUs 211, one or more DUs 231, or both, and the O-eNB 213 with the near-RT RIC 227.

[0088] In some implementations, the non-RT RIC 217 can receive parameters or external enrichment information from an external server in order to generate an AI / ML model to be deployed in the near-RT RIC 227. Such information can be utilized by the near-RT RIC 227 and can be received from non-network data sources or from network functions at the SMO framework 207 or the non-RT RIC 217. In some examples, the non-RT RIC 217 or the near-RT RIC 227 can be configured to tune RAN behavior or performance. For example, the non-RT RIC 217 can monitor long-term trends and patterns in performance and employ AI / ML models to perform corrective actions through the SMO framework 207 (such as via reconfiguration of O1) or by creating RAN management policies (such as A1 policies).

[0089] Various radio frame structures may be used to support downlink transmissions, uplink transmissions, and sidelink transmissions between network nodes (eg, a base station and a UE). Figure 3 is a diagram 300 illustrating an example of a frame structure that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimation at harmonic frequencies. Other wireless communication technologies may have different frame structures and / or different channels.

[0090] NR (and LTE) utilizes OFDM on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. However, unlike LTE, NR also has the option of using OFDM on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also often called tones, bins, etc. Each subcarrier can be modulated with data. Generally speaking, modulation symbols are transmitted in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the subcarrier spacing can be 15kHz, and the minimum resource allocation (resource block) can be 12 subcarriers (or 180kHz). Thus, for a system bandwidth of 1.25 megahertz (MHz), 2.5 MHz, 5 MHz, 10 MHz, or 20 MHz, the nominal Fast Fourier Transform (FFT) size may be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth may also be divided into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for a system bandwidth of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, or 20 MHz, respectively.

[0091] LTE supports a single parameter set (subcarrier spacing, symbol length, etc.). In contrast, NR can support multiple parameter sets (μ). For example, 15kHz, 30kHz, 60kHz, 120kHz, and 240kHz or larger subcarrier spacing (SCS) may be available. Table 1 provided below lists some of the different parameters for different NR parameter sets.

[0092]

[0093] Table 1

[0094] In one example, a 15 kHz parameter set is used. Thus, in the time domain, a 10 millisecond (ms) frame is divided into 10 equally sized subframes, each 1 ms, and each subframe includes one time slot. Figure 3 , time is represented in the horizontal direction (eg, on the X-axis), where time increases from left to right, and frequency is represented in the vertical direction (eg, on the Y-axis), where frequency increases (or decreases) from bottom to top.

[0095] A resource grid may be used to represent time slots, each of which includes one or more time-concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)) in the frequency domain. Figure 3 An example of a resource block (RB) 302 is illustrated. Data or information for joint communication and sensing may be included in one or more RBs 302. RBs 302 are arranged by placing the time domain on the horizontal (or x-axis) and the frequency domain on the vertical (or y-axis). As shown, RBs 302 may be 180 kilohertz (kHz) wide in frequency and one slot long in time (where a slot is 1 millisecond (ms) in time). In some cases, a slot may include fourteen symbols (e.g., in slot configuration 0). RBs 302 include twelve subcarriers (along the y-axis) and fourteen symbols (along the x-axis).

[0096] The intersection of a symbol and a subcarrier may be referred to as a resource element (RE) 304 or a tone. Figure 3 RB 302 includes multiple REs, which include resource elements (REs) 304. For example, RE 304 is 1 subcarrier x 1 symbol (e.g., OFDM symbol) and is the smallest discrete part of a subframe. RE 304 includes a single complex value representing data from a physical channel or signal. The number of bits carried by each RE 304 depends on the modulation scheme.

[0097] In some aspects, some REs 304 may be used to transmit downlink reference (pilot) signals (DL-RS). DL-RS may include positioning reference signals (PRS), tracking reference signals (TRS), phase tracking reference signals (PTRS), channel state information reference signals (CSI-RS), demodulation reference signals (DMRS), primary synchronization signals (PSS), secondary synchronization signals (SSS), etc. Figure 3 The resource grid of exemplifies exemplary locations of REs 304 (labeled “R”) for transmitting DL-RS.

[0098] Figure 4 is a block diagram illustrating an example of a computing system 470 of an electronic device 407 that may be employed by the disclosed systems and techniques for locating passive devices based on differential carrier phase estimation at harmonic frequencies. The electronic device 407 is an example of a device that may include hardware and software for connecting to and exchanging data with other devices and systems using a communication network (e.g., a third-generation partner network such as a fifth-generation (5G) / new radio (NR) network, a fourth-generation (4G) / long-term evolution (LTE) network, a WiFi network, or other communication network). For example, the electronic device 407 may include or be a portion of a mobile device (e.g., a mobile phone), a wearable device (e.g., a web-connected or smartwatch), an extended reality device (e.g., a virtual reality (VR) device, an augmented reality (AR) device, or a mixed reality (MR) device), a personal computer, a laptop computer, a tablet computer, an Internet of Things (IoT) device, a wireless access point, a router, a vehicle or a component of a vehicle, a server computer, a robotic device, and / or other device used by a user to communicate over a wireless communication network. In some cases, such as when referring to a device configured to communicate using 5G / NR, 4G / LTE, or other telecommunication standards, the device 407 may be referred to as a user equipment (UE). In some cases, such as when referring to a device configured to communicate using the Wi-Fi standard, the device may be referred to as a station (STA).

[0099] The computing system 470 includes software and hardware components that may be electrically or communicatively coupled via a bus 489 (or may communicate in other ways, as appropriate). For example, the computing system 470 includes one or more processors 484. The one or more processors 484 may include one or more CPUs, ASICs, FPGAs, APs, GPUs, VPUs, NSPs, microcontrollers, dedicated hardware, any combination thereof, and / or other processing devices and / or systems. The bus 489 may be used by the one or more processors 484 to communicate between cores and / or with one or more memory devices 486.

[0100] The computing system 470 may also include one or more memory devices 486, one or more digital signal processors (DSPs) 482, one or more subscriber identity modules (SIMs) 474, one or more modems 476, one or more wireless transceivers 478, one or more antennas 487, one or more input devices 472 (e.g., a camera, a mouse, a keyboard, a touch-sensitive screen, a touchpad, a keypad, a microphone or microphone array, etc.), and one or more output devices 480 (e.g., a display, a speaker, a printer, etc.).

[0101] One or more wireless transceivers 478 can receive wireless signals (e.g., signal 488) via antenna 487 from one or more other devices such as other user devices, network devices (e.g., base stations such as evolved NodeB (eNB) and / or gNodeB (gNB), WiFi access points (AP) such as routers, range extenders, etc.), cloud networks, etc. In some examples, the computing system 470 may include multiple antennas or antenna arrays that can facilitate simultaneous transmission and reception functionality. Antenna 487 can be an omnidirectional antenna so that RF signals can be received from all directions and RF signals can be transmitted in all directions. Wireless signal 488 can be sent via a wireless network. The wireless network can be any wireless network, such as a cellular or telecommunications network (e.g., 3G, 4G, 5G, etc.), a wireless local area network (e.g., a WiFi network), a Bluetooth TM network and / or other networks. In some examples, one or more wireless transceivers 478 may include an RF front end that includes one or more components such as an amplifier, a mixer for down-converting a signal (also known as a signal multiplier), a frequency synthesizer (also known as an oscillator) that provides the signal to the mixer, a baseband filter, an analog-to-digital converter (ADC), one or more power amplifiers, and other components. The RF front end generally handles the selection of wireless signals 488 and the conversion of the wireless signals to baseband or an intermediate frequency, and may convert the RF signals to the digital domain.

[0102] In some cases, computing system 470 may include a coding-decoding device (or codec) configured to encode and / or decode data transmitted and / or received using one or more wireless transceivers 478. In some cases, computing system 470 may include an encryption-decryption device or component configured to encrypt and / or decrypt data transmitted and / or received by one or more wireless transceivers 478 (e.g., in accordance with the Advanced Encryption Standard (AES) and / or Data Encryption Standard (DES) standards).

[0103] One or more SIMs 474 can each securely store an International Mobile Subscriber Identity (IMSI) number and associated keys assigned to a user of the electronic device 407. The IMSI and keys can be used to identify and authenticate the subscriber when accessing a network provided by a network service provider or operator associated with the one or more SIMs 474. One or more modems 476 can modulate one or more signals to encode information for transmission using one or more wireless transceivers 478. One or more modems 476 can also demodulate signals received by one or more wireless transceivers 478 to decode the transmitted information. In some examples, one or more modems 476 may include a WiFi modem, a 4G (or LTE) modem, a 5G (or NR) modem, and / or other types of modems. One or more modems 476 and one or more wireless transceivers 478 can be used to communicate data of one or more SIMs 474.

[0104] The computing system 470 may also include (and / or communicate with) one or more non-transitory machine-readable storage media or storage devices (e.g., one or more memory devices 486), which may include, but are not limited to, local and / or network-accessible storage devices, disk drives, drive arrays, optical storage devices, solid-state storage devices (such as RAM and / or ROM), which may be programmable, flash-updatable, and / or the like. Such storage devices may be configured to implement any suitable data storage, including, but not limited to, various file systems, database structures, and the like.

[0105] In various aspects, the functionality may be stored as one or more computer program products (e.g., instructions or code) in the memory device 486 and executed by the one or more processors 484 and / or the one or more DSPs 482. The computing system 470 may also include software elements (e.g., located within the one or more memory devices 486) including, for example, an operating system, device drivers, executable libraries, and / or other code, such as one or more application programs, which may include computer programs that implement the functionality provided by the various aspects and / or may be designed to implement methods and / or configure systems, as described herein.

[0106] In some aspects, the electronic device 407 may include means for performing the operations described herein. The means may include one or more components of the computing system 470. For example, the means for performing the operations described herein may include one or more of an input device 472, a SIM 474, a modem 476, a wireless transceiver 478, an output device 480, a DSP 482, a processor 484, a memory device 486, and / or an antenna 487.

[0107] In some aspects, the electronic device 407 may include components for locating passive devices based on differential carrier phase estimates at harmonic frequencies. In some examples, any or all of these components may include one or more wireless transceivers 478, one or more modems 476, one or more processors 484, one or more DSPs 482, one or more memory devices 486, any combination thereof, or other components of the electronic device 407.

[0108] Figure 5 is a diagram illustrating an example of a wireless device 500 utilizing RF monostatic sensing techniques for determining one or more characteristics (eg, position, velocity or speed, heading, etc.) of a target 502 object. Specifically, Figure 5 is a diagram illustrating an example of a wireless device 500 (e.g., a transmit / receive sensing node) that utilizes RF sensing technology (e.g., single-station sensing) to perform one or more functions, such as detecting the presence and location of a target 502 (e.g., an object, user, or vehicle), which is illustrated in the figure as a vehicle.

[0109] In some examples, wireless device 500 may be a mobile phone, a tablet computer, a wearable device, a vehicle, an extended reality (XR) device, a computing device or component of a vehicle, or other device that includes at least one RF interface (e.g., Figure 4 In some examples, the wireless device 500 may be a user device (e.g., Figure 4 An electronic device 407) provides connectivity, such as a base station (e.g., gNB, eNB, etc.), a wireless access point (AP), or other device including at least one RF interface.

[0110] In some aspects, the wireless device 500 may include one or more components for transmitting RF signals. The wireless device 500 may include at least one processor 522 for generating a digital signal or waveform. The wireless device 500 may also include a digital-to-analog converter (DAC) 504 capable of receiving a digital signal or waveform from the processor 522 (e.g., a microprocessor) and converting the digital signal or waveform into an analog waveform. The analog signal as an output of the DAC 504 may be provided to the RF transmitter 506 for transmission. The RF transmitter 506 may be a Wi-Fi transmitter, a 5G / NR transmitter, a Bluetooth transmitter, or a similar transmitter. TM transmitter or any other transmitter capable of transmitting RF signals.

[0111] The RF transmitter 506 can be coupled to one or more transmit antennas, such as a Tx antenna 512. In some examples, the transmit (Tx) antenna 512 can be an omnidirectional antenna capable of transmitting RF signals in all directions. For example, the Tx antenna 512 can be an omnidirectional Wi-Fi antenna capable of radiating Wi-Fi signals (e.g., 2.4 GHz, 5 GHz, 6 GHz, etc.) in a 360-degree radiation pattern. In another example, the Tx antenna 512 can be a directional antenna that transmits RF signals in a specific direction.

[0112] In some examples, the wireless device 500 may also include one or more components for receiving RF signals. For example, the receiver array in the wireless device 500 may include one or more receive antennas, such as a receive (Rx) antenna 514. In some examples, the Rx antenna 514 may be an omnidirectional antenna capable of receiving RF signals from multiple directions. In other examples, the Rx antenna 514 may be a directional antenna configured to receive signals from a specific direction. In another example, the Tx antenna 512 and / or the Rx antenna 514 may include multiple antennas (e.g., elements) configured as an antenna array (e.g., a phased antenna array).

[0113] The wireless device 500 may also include an RF receiver 510 coupled to an Rx antenna 514. The RF receiver 510 may include a signal source for receiving RF waveforms such as Wi-Fi signals, Bluetooth signals, TM The RF receiver 510 may be coupled to an analog-to-digital converter (ADC) 508 to receive a received analog RF waveform. The ADC 508 may be configured to convert the received analog RF waveform into a digital waveform. The digital waveform as an output of the ADC 508 may be provided to a processor 522 for processing. The processor 522 (e.g., a digital signal processor (DSP)) may be configured to process the digital waveform.

[0114] In one example, the wireless device 500 can implement an RF sensing technique, such as a single-station sensing technique, by transmitting a Tx waveform 516 from the Tx antenna 512. Although the Tx waveform 516 is illustrated as a single line, in some cases, the Tx waveform 516 can be transmitted in all directions by the omnidirectional Tx antenna 512. In one example, the Tx waveform 516 can be a Wi-Fi waveform transmitted by a Wi-Fi transmitter in the wireless device 500. In some cases, the Tx waveform 516 can correspond to a Wi-Fi waveform transmitted simultaneously or nearly simultaneously with a Wi-Fi data communication signal or a Wi-Fi control function signal (e.g., a beacon transmission). In some examples, the Tx waveform 516 can be transmitted using the same or similar frequency resources as the Wi-Fi data communication signal or the Wi-Fi control function signal (e.g., a beacon transmission). In some aspects, the Tx waveform 516 can correspond to a Wi-Fi waveform transmitted separately from the Wi-Fi data communication signal and / or the Wi-Fi control signal (e.g., the Tx waveform 516 can be transmitted at a different time and / or using different frequency resources).

[0115] In some examples, Tx waveform 516 can correspond to a 5G NR waveform that is transmitted simultaneously or nearly simultaneously with a 5G NR data communication signal or a 5G NR control function signal. In some examples, Tx waveform 516 can be transmitted using the same or similar frequency resources as the 5G NR data communication signal or the 5G NR control function signal. In some aspects, Tx waveform 516 can correspond to a 5G NR waveform that is transmitted separately from the 5G NR data communication signal and / or the 5G NR control signal (e.g., Tx waveform 516 can be transmitted at a different time and / or using different frequency resources).

[0116] In some aspects, one or more parameters associated with the Tx waveform 516 can be modified, which can be used to increase or decrease RF sensing resolution. These parameters can include frequency, bandwidth, number of spatial streams, number of antennas configured to transmit the Tx waveform 516, number of antennas configured to receive reflected RF signals corresponding to the Tx waveform 516 (e.g., Rx waveform 518), number of spatial links (e.g., number of spatial streams multiplied by number of antennas configured to receive RF signals), sampling rate, or any combination thereof. The transmitted waveform (e.g., Tx waveform 516) and the received waveform (e.g., Rx waveform 518) can include one or more RF sensing signals, also referred to as radar reference signals (RS).

[0117] In another example, the Tx waveform 516 can be implemented as a sequence with perfect or nearly perfect autocorrelation properties. For example, the Tx waveform 516 can include a single-carrier Zadoff sequence or can include symbols similar to orthogonal frequency division multiplexing (OFDM) long training field (LTF) symbols. In some cases, the Tx waveform 516 can include a chirp signal, such as used in frequency modulated continuous wave (FM-CW) radar systems. In some configurations, the chirp signal can include a signal in which the signal frequency increases and / or decreases periodically in a linear and / or exponential manner.

[0118] In some aspects, the wireless device 500 can implement RF sensing technology by performing alternating transmit and receive functions (e.g., performing half-duplex operation). For example, the wireless device 500 can alternately enable its RF transmitter 506 to transmit a Tx waveform 516 when the RF receiver 510 is not enabled to receive (i.e., not receiving), and enable its RF receiver 510 to receive an Rx waveform 518 when the RF transmitter 506 is not enabled to transmit (i.e., not transmitting). When the wireless device 500 performs half-duplex operation, the wireless device 500 can transmit a Tx waveform 516, which can be a radar RS (e.g., a sensing signal).

[0119] In other aspects, the wireless device 500 can implement RF sensing techniques by performing concurrent transmit and receive functions (e.g., performing sub-band or full-band full-duplex operation). For example, the wireless device 500 can enable its RF receiver 510 to receive at or near the same time as it enables its RF transmitter 506 to transmit a Tx waveform 516. When the wireless device 500 performs full-duplex operation (e.g., sub-band full-duplex or full-band full-duplex), the wireless device 500 can transmit a Tx waveform 516, which can be a radar RS (e.g., a sensing signal).

[0120] In some examples, the transmission of a sequence or pattern included in the Tx waveform 516 can be repeated continuously, such that the sequence is transmitted a specific number of times or for a specific duration. In some examples, if the RF receiver 510 is enabled after the RF transmitter 506, the repetition of the pattern in the transmission of the Tx waveform 516 can be used to avoid missing the reception of any reflected signals. In one example implementation, the Tx waveform 516 can include a sequence having a sequence length L that is transmitted two or more times, which can allow the RF receiver 510 to be enabled for a time less than or equal to L to receive reflections corresponding to the entire sequence without losing any information.

[0121] By implementing alternating or simultaneous transmit and receive functionality (e.g., half-duplex or full-duplex operation), the wireless device 500 can receive signals corresponding to the Tx waveform 516. For example, the wireless device 500 can receive signals reflected from objects or people within the range of the Tx waveform 516, such as the Rx waveform 518 reflected from the target 502. The wireless device 500 can also receive leakage signals (e.g., Tx leakage signal 520) that are directly coupled from the Tx antenna 512 to the Rx antenna 514 without reflecting from any objects. For example, the leakage signal may include a signal that passes from a transmitter antenna (e.g., Tx antenna 512) on the wireless device to a receive antenna (e.g., Rx antenna 514) on the wireless device without reflecting from any objects. In some cases, the Rx waveform 518 may include multiple sequences corresponding to multiple copies of the sequence included in the Tx waveform 516. In some examples, the wireless device 500 may combine multiple sequences received by the RF receiver 510 to improve the signal-to-noise ratio (SNR).

[0122] The wireless device 500 may also implement RF sensing techniques by obtaining RF sensing data associated with each of the received signals corresponding to the Tx waveform 516. In some examples, the RF sensing data may include channel state information (CSI) data related to a direct path (e.g., leakage signal 520) of the Tx waveform 516 and data related to a reflected path (e.g., Rx waveform 518) corresponding to the Tx waveform 516.

[0123] In some aspects, the RF sensing data (e.g., CSI data) may include information that can be used to determine how an RF signal (e.g., Tx waveform 516) propagates from the RF transmitter 506 to the RF receiver 510. The RF sensing data may include data corresponding to the effects on the transmitted RF signal due to scattering, fading, and / or power attenuation with distance, or any combination thereof. In some examples, the RF sensing data may include imaginary data and real data (e.g., I / Q components) corresponding to each tone in the frequency domain over a particular bandwidth.

[0124] In some examples, the RF sensing data can be used by processor 522 to calculate the distance and angle of arrival corresponding to a reflected waveform, such as Rx waveform 518. In other examples, the RF sensing data can also be used to detect motion, determine position, detect changes in position or motion patterns, or any combination thereof. In some cases, the distance and angle of arrival of the reflected signal can be used to identify the size, position, movement, and / or orientation of an object (e.g., object 502) in the surrounding environment to detect object presence / proximity.

[0125] The processor 522 of the wireless device 500 can calculate the distance and arrival angle corresponding to the reflected waveform (e.g., the distance and arrival angle corresponding to the Rx waveform 518) by utilizing signal processing, machine learning algorithms, any other suitable technology, or any combination thereof. In other examples, the wireless device 500 can send or transmit the RF sensing data to at least one processor of another computing device, such as a server or a base station, and the other computing device can perform calculations to obtain the distance and arrival angle corresponding to the Rx waveform 518 or other reflected waveforms.

[0126] In one example, the distance of the Rx waveform 518 can be calculated by measuring the time difference between receiving the leakage signal and receiving the reflected signal. For example, the wireless device 500 can determine a baseline distance of zero based on the difference between the time the wireless device 500 transmits the Tx waveform 516 and the time it receives the leakage signal 520 (e.g., propagation delay). The processor 522 of the wireless device 500 can then determine the distance associated with the Rx waveform 518 based on the difference between the time the wireless device 500 transmits the Tx waveform 516 and the time it receives the Rx waveform 518 (e.g., flight time, also known as round-trip time (RTT)). The distance can then be adjusted based on the propagation delay associated with the leakage signal 520. By doing so, the processor 522 of the wireless device 500 can determine the distance traveled by the Rx waveform 518, which can be used to determine the presence and movement of the target (e.g., target 502) that caused the reflection.

[0127] In another example, the angle of arrival of the Rx waveform 518 can be calculated by the processor 522 by measuring the time difference of arrival of the Rx waveform 518 between various elements of the receive antenna array, such as the antenna 514. In some examples, the time difference of arrival can be calculated by measuring the difference in the received phase at each element in the receive antenna array.

[0128] In some cases, the distance and angle of arrival of the Rx waveform 518 can be used by the processor 522 to determine the distance between the wireless device 500 and the target 502, as well as the position of the target 502 relative to the wireless device 500. The distance and angle of arrival of the Rx waveform 518 can also be used to determine the presence, movement, proximity, identity, or any combination thereof of the target 502. For example, the processor 522 of the wireless device 500 can use the calculated distance and angle of arrival corresponding to the Rx waveform 518 to determine that the target 502 is moving toward the wireless device 500.

[0129] As mentioned above, the wireless device 500 may include a mobile device (e.g., an IoT device, a smartphone, a laptop, a tablet device, etc.) or other type of device. In some examples, the wireless device 500 may be configured to obtain device location data and device orientation data in addition to the RF sensing data. In some cases, the device location data and device orientation data may be used to determine or adjust the range and angle of arrival of a reflected signal, such as the Rx waveform 518. For example, when a target 502 (e.g., a vehicle) moves toward the wireless device 500 during the RF sensing process, the wireless device may be positioned on the ground facing the sky. In this case, the wireless device 500 may use its location data and orientation data in addition to the RF sensing data to determine the direction in which the target 502 is moving.

[0130] In some examples, the wireless device 500 can collect device location data using techniques including RTT measurements, time of arrival (TOA) measurements, time difference of arrival (TDOA) measurements, passive positioning measurements, angle of arrival (AOA) measurements, angle of departure (AoD) measurements, received signal strength indicator (RSSI) measurements, CSI data, using any other suitable techniques, or any combination thereof. In another example, device orientation data can be obtained from electronic sensors on the wireless device 500, such as a gyroscope, accelerometer, compass, magnetometer, barometer, any other suitable sensor, or any combination thereof.

[0131] Figure 6 is a diagram illustrating an example of a receiver 604 utilizing RF monostatic sensing techniques with one transmitter 600 for determining one or more characteristics (e.g., position, velocity or speed, heading, etc.) of a target 602 object. For example, the receiver 604 may use RF bistatic sensing to detect the presence and position of a target 602 (e.g., an object, user, or vehicle) that is located at a location within a certain range. Figure 6 In one example, the receiver 604 may be in the form of a base station such as a gNB.

[0132] Figure 6 The bistatic radar system includes a transmitter 600 (e.g., a transmitting sensing node), which is depicted in the figure as being in the form of a base station (e.g., a gNB), and a receiver 604 (e.g., a receiving sensing node), which are separated by a distance comparable to the expected target distance. Figure 5 Compared with the single-station system, Figure 6 The transmitter 600 and receiver 604 of a bistatic radar system are located remotely from each other. In contrast, a monostatic radar is one that includes co-located transmitters (e.g., Figure 5 RF transmitter 506 of the wireless device 500) and receiver (e.g., Figure 5The RF receiver 510 of the wireless device 500) of the radar system (e.g., Figure 5 system).

[0133] An advantage of a bistatic radar (or more generally, a multistatic radar with more than one receiver) over a monostatic radar is the ability to collect radar echoes reflected from a scene at angles different from the angle at which the pulse was transmitted. This may be of interest in some applications (e.g., vehicle applications, scenes with multiple objects, military applications, etc.), where targets may reflect transmitted energy in many directions (e.g., where the targets are specifically designed to reflect in many directions), which can minimize the energy reflected back to the transmitter. It should be noted that in one or more examples, a monostatic system can coexist with a multistatic radar system, such as when the transmitter also has a co-located receiver.

[0134] In some examples, Figure 6 The transmitter 600 and / or the receiver 604 may be a mobile phone, a tablet computer, a wearable device, a vehicle, or other device including at least one RF interface (e.g., Figure 4 In some examples, the transmitter 600 and / or the receiver 604 may be a user device (e.g., Figure 4 IoT device 407) provides connectivity to the device, such as a base station (e.g., gNB, eNB, etc.), a wireless access point (AP), or other device including at least one RF interface.

[0135] In some aspects, the transmitter 600 may include one or more components for transmitting RF signals. The transmitter 600 may include at least one processor (e.g., Figure 5 The transmitter 600 may further include an RF transmitter (e.g., Figure 5 The RF transmitter 506 may be a transmitter configured to transmit a cellular signal or a telecommunication signal (e.g., a transmitter configured to transmit a 5G / NR signal, a 4G / LTE signal, or other cellular signal / telecommunication signal, etc.), a Wi-Fi transmitter, a Bluetooth transmitter, or a similar transmitter. TM transmitter, any combination thereof, or any other transmitter capable of transmitting RF signals.

[0136] The RF transmitter may be coupled to one or more transmit antennas, such as Tx antennas (e.g., Figure 5TX antenna 512). In some examples, the Tx antenna can be an omnidirectional antenna capable of transmitting RF signals in all directions, or a directional antenna capable of transmitting RF signals in a specific direction. In some examples, the Tx antenna can include multiple antennas (e.g., elements) configured as an antenna array.

[0137] The receiver 604 may also include one or more components for receiving RF signals. For example, the receiver 604 may include one or more receive antennas, such as Rx antennas (e.g., Figure 5 In some examples, the Rx antenna may be an omnidirectional antenna capable of receiving RF signals from multiple directions, or a directional antenna configured to receive signals from a specific direction. In other examples, the Rx antenna may include multiple antennas (e.g., elements) configured as an antenna array.

[0138] The receiver 604 may also include an RF receiver (eg, Figure 5 The RF receiver may include a RF receiver 510 for receiving RF waveforms (such as Wi-Fi signals, Bluetooth TM signals, 5G / NR signals, or any other RF signals). The output of the RF receiver may be coupled to at least one processor (e.g., Figure 5 The processor may be configured to process the received waveform (eg, Rx waveform 618).

[0139] In one or more examples, the transmitter 600 can implement an RF sensing technique, such as a bistatic sensing technique, by transmitting a Tx waveform 616 from the Tx antenna. It should be noted that although the Tx waveform 616 is illustrated as a single line, in some cases, the Tx waveform 616 can be transmitted in all directions by an omnidirectional Tx antenna.

[0140] In one or more aspects, one or more parameters associated with the Tx waveform 616 can be used to increase or decrease RF sensing resolution. These parameters may include frequency, bandwidth, number of spatial streams, number of antennas configured to transmit the Tx waveform 616, number of antennas configured to receive reflected RF signals corresponding to the Tx waveform 616 (e.g., Rx waveform 618), number of spatial links (e.g., number of spatial streams multiplied by number of antennas configured to receive RF signals), sampling rate, or any combination thereof. The transmitted waveform (e.g., Tx waveform 616) and the received waveform (e.g., Rx waveform 618) may include one or more radar RF sensing signals (also referred to as RF sensing RS).

[0141] During operation, the receiver 604 (e.g., operating as a receiving sensing node) can receive a signal corresponding to the Tx waveform 616, which is transmitted by the transmitter 600 (e.g., operating as a transmitting sensing node). For example, the receiver 604 can receive a signal reflected from an object or person within the range of the Tx waveform 616, such as the Rx waveform 618 reflected from the target 602. In some cases, the Rx waveform 618 may include multiple sequences corresponding to multiple copies of the sequence included in the Tx waveform 616. In some examples, the receiver 604 can combine the received multiple sequences to improve the SNR.

[0142] In some examples, at least one processor within receiver 604 can use the RF sensing data to calculate a distance, angle of arrival, or other characteristics corresponding to a reflected waveform, such as Rx waveform 618. In other examples, the RF sensing data can also be used to detect motion, determine position, detect a change in position or motion pattern, or any combination thereof. In some cases, the distance and angle of arrival of the reflected signal can be used to identify the size, position, movement, and / or orientation of an object (e.g., object 602) in the surrounding environment in order to detect object presence / proximity.

[0143] The processor of the receiver 604 may calculate the distance and arrival angle corresponding to the reflected waveform (e.g., the distance and arrival angle corresponding to the Rx waveform 618) by using signal processing, machine learning algorithms, any other suitable technology, or any combination thereof. In other examples, the receiver 604 may send or transmit the RF sensing data to at least one processor of another computing device, such as a server, which may perform calculations to obtain the distance and arrival angle corresponding to the Rx waveform 618 or other reflected waveforms.

[0144] In one or more examples, the angle of arrival of the Rx waveform 618 can be calculated by the processor of the receiver 604 by measuring the time difference of arrival of the Rx waveform 618 between various elements of the receive antenna array of the receiver 604. In some examples, the time difference of arrival can be calculated by measuring the difference in the received phase at each element in the receive antenna array.

[0145] In some cases, the distance and angle of arrival of the Rx waveform 618 can be used by the processor of the receiver 604 to determine the distance between the receiver 604 and the target 602, as well as the position of the target 602 relative to the receiver 604. The distance and angle of arrival of the Rx waveform 618 can also be used to determine the presence, movement, proximity, identity, or any combination thereof of the target 602. For example, the processor of the receiver 604 can use the calculated distance and angle of arrival corresponding to the Rx waveform 618 to determine that the target 602 is moving toward the receiver 604.

[0146] Figure 7 7 is a diagram illustrating an example of a receiver 704 in the form of a smartphone utilizing RF bistatic sensing technology with multiple transmitters (including transmitter 700a, transmitter 700b, and transmitter 700c) that can be used to determine one or more characteristics (e.g., position, speed or velocity, heading, etc.) of a target 702 object. For example, receiver 704 can use RF bistatic sensing to detect the presence and location of target 702 (e.g., an object, user, or vehicle). Target 702 is located at Figure 7 The depiction is of objects without communication capabilities (which may be referred to as device-less objects), such as people, vehicles (e.g., vehicles without the ability to send and receive messages, such as using C-V2X or DSRC protocols), or other device-less objects. Figure 7 The bistatic radar system is similar to Figure 6 The difference between the dual-station radar system and the Figure 7 The bistatic radar system has multiple transmitters 700a, 700b, 700c, and Figure 6 The bistatic radar system has only one transmitter 600 .

[0147] Figure 7 The bistatic radar system of includes a plurality of transmitters 700a, 700b, 700c (eg, transmitting sensing nodes), which are illustrated as being in the form of base stations. Figure 7 The bistatic radar system of also includes a receiver 704 (e.g., a receiving sensing node) depicted in the form of a smartphone. The distance separating each of the transmitters 700a, 700b, 700c from the receiver 704 can be compared to the expected distance to the target 702. Similar to Figure 6 The dual-station system Figure 7 The transmitters 700a, 700b, 700c and the receiver 704 of the bistatic radar system are located remotely from each other.

[0148] In one or more examples, transmitters 700a, 700b, 700c, and / or receiver 704 can each be a mobile phone, a tablet computer, a wearable device, a vehicle (e.g., a vehicle configured to transmit and receive communications according to C-V2X, DSRC, or other communication protocols), or other devices including at least one RF interface (e.g., Figure 4 In some examples, transmitters 700a, 700b, 700c and / or receiver 704 may each be a user device (e.g., Figure 4 IoT device 407) provides connectivity to the device, such as a base station (e.g., gNB, eNB, etc.), a wireless access point (AP), or other device including at least one RF interface.

[0149] The transmitters 700a, 700b, 700c may include one or more components for transmitting RF signals. Each of the transmitters 700a, 700b, 700c may include at least one processor (e.g., Figure 5 Each of the transmitters 700a, 700b, 700c may also include an RF transmitter (e.g., a RF transmitter) for transmitting Tx signals including Tx waveforms 716a, 716b, 716c, 720a, 720b, 720c. Figure 5 RF transmitter 506). In one or more examples, Tx waveforms 716a, 716b, 716c are RF sensing signals, and Tx waveforms 720a, 720b, 720c are communication signals. In one or more examples, Tx waveforms 720a, 720b, 720c are communication signals that can be used to schedule a transmitter (e.g., transmitters 700a, 700b, 700c) and a receiver (e.g., receiver 704) to perform RF sensing of a target (e.g., target 702) to obtain location information about the target. The RF transmitter can be a transmitter configured to transmit a cellular signal or a telecommunication signal (e.g., a transmitter configured to transmit a 5G / NR signal, a 4G / LTE signal, or other cellular signal / telecommunication signal, etc.), a Wi-Fi transmitter, a Bluetooth transmitter, or a similar transmitter. TM transmitter, any combination thereof, or any other transmitter capable of transmitting RF signals.

[0150] The RF transmitter may be coupled to one or more transmit antennas, such as Tx antennas (e.g., Figure 5 TX antenna 512). In one or more examples, the Tx antenna can be an omnidirectional antenna capable of transmitting RF signals in all directions, or a directional antenna that transmits RF signals in a specific direction. The Tx antenna may include multiple antennas (e.g., elements) configured as an antenna array.

[0151] Figure 7 The receiver 704 may include one or more components for receiving RF signals. For example, the receiver 704 may include one or more receiving antennas, such as Rx antennas (e.g., Figure 5 RX antenna 514). In one or more examples, the RX antenna can be an omnidirectional antenna capable of receiving RF signals from multiple directions, or a directional antenna configured to receive signals from a specific direction. In some examples, the RX antenna can include multiple antennas (e.g., elements) configured as an antenna array (e.g., a phased antenna array).

[0152] The receiver 704 may also include an RF receiver (eg, Figure 5The RF receiver may include a RF receiver 510 for receiving RF waveforms (such as Wi-Fi signals, Bluetooth TM signals, 5G / NR signals, or any other RF signals). The output of the RF receiver may be coupled to at least one processor (e.g., Figure 5 The processor 522 may be configured to process the received waveform (eg, Rx waveform 718, which is the reflected (echo) RF sensing signal).

[0153] In some examples, transmitters 700a, 700b, 700c can implement RF sensing techniques (e.g., bistatic sensing techniques) by transmitting Tx waveforms 716a, 716b, 716c (e.g., radar sensing signals) from Tx antennas associated with each of the transmitters 700a, 700b, 700c. Although the Tx waveforms 716a, 716b, 716c are illustrated as a single line, in some cases, the Tx waveforms 716a, 716b, 716c can be transmitted in all directions (e.g., via omnidirectional Tx antennas associated with each of the transmitters 700a, 700b, 700c).

[0154] In one or more aspects, one or more parameters associated with the Tx waveforms 716a, 716b, 716c can be used to increase or decrease RF sensing resolution. These parameters may include, but are not limited to, frequency, bandwidth, number of spatial streams, number of antennas configured to transmit the Tx waveforms 716a, 716b, 716c, number of antennas configured to receive reflected (echo) RF signals corresponding to each of the Tx waveforms 716a, 716b, 716c (e.g., Rx waveform 718), number of spatial links (e.g., number of spatial streams multiplied by number of antennas configured to receive RF signals), sampling rate, or any combination thereof. The transmitted waveforms (e.g., Tx waveforms 716a, 716b, 716c) and the received waveforms (e.g., Rx waveform 718) may include one or more radar RF sensing signals (also referred to as RF sensing RS). It should be noted that although Figure 7 Only one reflected sensing signal (eg, Rx waveform 718 ) is shown in , but it should be understood that a separate reflected (echo) sensing signal will be generated by each sensing signal reflected from the target 702 (eg, Tx waveforms 716 a , 716 b , 716 c ).

[0155] exist Figure 7During operation of the system, a receiver 704 (e.g., operating as a receiving sensing node) can receive signals corresponding to Tx waveforms 716a, 716b, 716c transmitted by transmitters 700a, 700b, 700c (e.g., each operating as a transmitting sensing node). The receiver 704 can receive signals reflected from objects or people within the range of the Tx waveforms 716a, 716b, 716c, such as the Rx waveform 718 reflected from the target 702. In one or more examples, the Rx waveform 718 can include multiple sequences corresponding to multiple copies of the sequence included in its corresponding Tx waveform 716a, 716b, 716c. In some examples, the receiver 704 can combine the received multiple sequences to improve the SNR.

[0156] In some examples, the RF sensing data can be used by at least one processor within receiver 704 to calculate distance, angle of arrival (AOA), TDOA, angle of departure (AoD), or other characteristics corresponding to a reflected waveform (e.g., Rx waveform 718). In other examples, the RF sensing data can also be used to detect motion, determine position, detect changes in position or motion patterns, or any combination thereof. In one or more examples, the distance and angle of arrival of the reflected signal can be used to identify the size, position, movement, and / or orientation of a target (e.g., target 702) in order to detect target presence / proximity.

[0157] The processor of the receiver 704 can calculate the distance and arrival angle corresponding to the reflected waveform (e.g., the distance and arrival angle corresponding to the Rx waveform 718) by using signal processing, machine learning algorithms, any other suitable technology, or any combination thereof. In one or more examples, the receiver 704 can send or transmit the RF sensing data to at least one processor of another computing device, such as a server, which can perform calculations to obtain the distance and arrival angle corresponding to the Rx waveform 718 or other reflected waveforms (not shown).

[0158] In one or more examples, the processor of the receiver 704 can calculate the angle of arrival (AOA) of the Rx waveform 718 by measuring the TDOA of the Rx waveform 718 between various elements of the receive antenna array of the receiver 704. In some examples, the TDOA can be calculated by measuring the difference in receive phase at each element in the receive antenna array. In one illustrative example, to determine the TDOA, the processor can determine the time difference of arrival of the Rx waveform 718 to the receive antenna array element using one of the receive antenna array elements as a reference. The time difference is proportional to the distance difference.

[0159] In some cases, the processor of the receiver 704 can use the range, AOA, TDOA, other measurement information (e.g., AoD, etc.), or any combination thereof, of the Rx waveform 718 to determine the distance between the receiver 704 and the target 702 and determine the position of the target 702 relative to the receiver 704. In one example, the processor can use the range, AOA, and / or TDOA information as input to apply multilateration or other location-based algorithms to determine the position (e.g., 3D position) of the target 702. In other examples, the processor can use the range, AOA, and / or TDOA of the Rx waveform 718 to determine the presence, movement (e.g., speed or velocity, heading or direction or movement, etc.), proximity, identity, any combination thereof, or other characteristics of the target 702. For example, the processor of the receiver 704 can use the range, AOA, and / or TDOA corresponding to the Rx waveform 718 to determine that the target is moving toward the receiver 704.

[0160] Figure 8 is a diagram illustrating the geometry for bistatic (or monostatic) sensing. Figure 8 The bistatic radar north reference coordinate system in two dimensions is shown. Specifically, Figure 8 The coordinate system and parameters for bistatic radar operation are shown, defined in a plane containing transmitter 800, receiver 804, and target 802 (referred to as the bistatic plane). The bistatic triangle lies in the bistatic plane. Transmitter 800, target 802, and receiver 804 are shown relative to each other. Transmitter 800 and receiver 804 are separated by a baseline distance L. An extended baseline is defined as extending the baseline distance L beyond either transmitter 800 or receiver 804. Target 802 and transmitter 800 are separated by a distance R. T , and the target 802 and the receiver 804 are separated by a distance R R .

[0161] Angle θ T and θ R are the transmitter 800 observation angle and the receiver 804 observation angle, respectively, which are considered positive when measured clockwise from North (N). Angle θ T and θ R Also known as the angle of arrival (AOA) or line of sight (LOS). The bistatic angle (β) is the angle between the transmitter 800, the target 802, and the receiver 804 in the radar. Specifically, the bistatic angle is the angle between the transmitter 800 and the receiver 804, with the apex at the target 802. The bistatic angle is equal to the observation angle of the transmitter 800 minus the observation angle θ of the receiver 804. R (For example, β = θ T -θ R ).

[0162] When the bistatic angle is exactly zero (0°), the radar is considered monostatic; when the bistatic angle is close to zero, the radar is considered pseudo-monostatic; and when the bistatic angle is close to 180 degrees, the radar is considered a forward-scattering radar. Otherwise, the radar is considered and referred to as a bistatic radar. The bistatic angle (β) can be used to determine the radar cross section of a target.

[0163] Figure 9 9 is a diagram illustrating an example of a bistatic distance 910 for bistatic sensing. In the diagram, a radar transmitter (Tx) 900, a target 902, and a receiver (Rx) 904 are shown relative to each other. The transmitter 900 is separated from the receiver 904 by a baseline distance L, the target 902 is separated from the transmitter 900 by a distance Rtx, and the target 902 is separated from the receiver 904 by a distance Rrx.

[0164] Bistatic range 910 (illustrated as an ellipse) refers to the range measurement made by a radar having a separate transmitter 900 and receiver 904 (e.g., transmitter 900 and receiver 904 are positioned far apart from each other). Receiver 904 measures the time of arrival from when transmitter 900 transmits a signal to when receiver 904 receives the signal from transmitter 900 via target 902. Bistatic range 910 defines an ellipse of constant bistatic distance, called an equidistant contour, on which target 902 is located, with the focal points centered on transmitter 900 and receiver 904. If target 902 is at distance Rrx from receiver 904 and at distance Rtx from transmitter 900, and receiver 904 and transmitter 900 are at distance L from each other, then the bistatic range equals Rrx + Rtx - L. It should be noted that the motion of target 902 causes the rate of change of the bistatic range, which results in a bistatic Doppler shift.

[0165] Typically, a constant bistatic distance point draws an ellipsoid with the transmitter 900 and receiver 904 locations as foci. The bistatic equidistant contour is where the ground cuts the ellipsoid. When the ground is flat, this intercept forms an ellipse (e.g., bistatic distance 910). Note that these ellipses are not centered on the mirror point unless the two platforms have equal heights.

[0166] As mentioned previously, passive devices have recently been introduced into wireless communication (e.g., 5G and 6G wireless communication) systems to reduce the cost of IoT devices and achieve zero-power green communication. Passive devices (e.g., network devices) may be referred to as passive UEs (pUEs), tags, environmental backscatter devices, or backscatter devices. Passive devices typically have no batteries or limited batteries within their terminals and rely on energy harvesting to power them. In order to collect energy, passive devices can accumulate energy from received radio signaling within their terminals, and in some cases, can also accumulate energy from solar energy within their terminals as a supplement. Passive devices typically do not contain radio wave (e.g., RF waveform) transmission circuitry. Therefore, passive devices can typically only output data (e.g., can only send information) by reflecting received radio waves. Key requirements for passive devices may include, but are not limited to, a coverage range of thirty meters (e.g., to build viable wireless network coverage in buildings up to 5,000 square meters in size, such as warehouses), power consumption of less than 0.1 mW to support operation without batteries, a cost of less than $0.02 to meet cost-sensitive applications, and / or 90% positioning accuracy within a distance of three to five meters (e.g., horizontally and vertically).

[0167] Passive devices may have multiple applicable use cases, which may include but are not limited to being used as industrial sensors where battery replacement is extremely difficult or undesirable (e.g., for safety monitoring or fault detection in smart factories, infrastructure, or environments); being used in smart logistics / warehousing due to their extremely low cost, small size, maintenance-free, durable, and long life (e.g., for automated asset management in factories to replace RFID tags); being used for household item management within smart home networks; being adopted in wearable devices (e.g., wearable devices for medical monitoring of patients where the patients do not need to replace the batteries themselves); and / or being used for environmental monitoring.

[0168] Passive devices can be used for both communication and sensing (eg, for locating the passive device). Figure 10 FIG. 1 is a diagram illustrating an example of a system 1000 that employs passive devices for communication. Figure 10, system 1000 is shown as including an RF source 1010 (e.g., a gNB), a legacy receiver 1020a (e.g., in the form of a laptop), a legacy receiver 1020b (e.g., in the form of a smartphone), a reader 1030 (e.g., or a sink node, which may be a UE), and a passive device 1040 (e.g., a pUE, such as a tag or sensor). The RF source 1010 (e.g., a gNB) is shown as transmitting communication signals 1050a, 1050b (e.g., x(n)) to the legacy devices 1020a, 1020b, respectively. The RF source 1010 (e.g., a gNB) is also shown as transmitting RF source signals 1060, 1070 to the reader 1030 and the passive device (e.g., a pUE), respectively. In one or more examples, for system 1000, the RF source 1010 may be a UE rather than a legacy device such as a gNB. Figure 10 The gNB shown, and the reader 1030 may be a gNB instead of Figure 10 UE shown.

[0169] For example, during operation for communication, the RF source 1010 (e.g., a gNB) may transmit an RF source waveform 1070 (e.g., an energy-harvesting radio wave) to the passive device 1040 (e.g., a pUE). After the passive device 1040 receives the RF source waveform 1070, the passive device 1040 may accumulate energy from the RF source waveform 1070 within a terminal of the passive device 1040. After the passive device 1040 has accumulated a sufficient amount of energy from the RF source waveform 1070, the passive device 1040 may begin reflecting (e.g., radiating) the RF source waveform 1070 radiated onto the passive device 1040 to generate a reflected RF source waveform 1080. The reflected RF source waveform 1080 of the RF source waveform 1070 may follow a specific on / off pattern. The on / off pattern may be based on control information (e.g., information bits) within a synchronization signal (SS) or a control signal (or channel) previously received by the passive device 1040. The reader 1030 (eg, UE) may then detect the reflection pattern of the reflected RF source waveform 1080 and obtain backscatter communication data from the reflected RF source waveform 1080 .

[0170] Figure 11 This example can be used in Figure 10 FIG1100 is a diagram illustrating examples of different signals transmitted and received within the system 1000. Figure 11 , diagram 1100 is shown as including Figure 101000 of a system 1000 includes an RF source 1010 (e.g., a gNB), a passive device 1040 (e.g., a pUE), and a reader 1030 (e.g., a UE). The various signals include a direct propagation signal 1110, which may be referred to as a direct link (e.g., in a LOS path between the RF source 1010 and the reader 1030), a backscatter link 1120 from the pUE to the reader 1030, and background reflection signals 1121. The passive device 1040 (e.g., a pUE) is shown to include: a power splitter 1130 for splitting the power of a received signal; an energy harvester for harvesting energy from the received signal (e.g., and in some cases, also for harvesting solar energy); a microcontroller 1150 for controlling the on and off switching of a reflection switch 1160 for reflection from the passive device 1040; and the reflection switch 1160.

[0171] During operation for communication, reader 1030 (e.g., UE) may receive interfering signals. These interfering signals may include direct propagation signals 1110 (e.g., direct link) and background reflection signals 1121, which are signals reflected by one or more background objects (e.g., background objects 1122) (such as the ground, trees, or another object other than passive device 1040). Direct propagation signal 1110 is shown as being transmitted directly from RF source 1010 (e.g., gNB) to reader 1030 (e.g., UE) (e.g., in a LOS path).

[0172] In one or more aspects, if the RF source transmits a sinusoidal wave (eg, having a carrier frequency f sin ) in the form of an RF source waveform, and the passive device (e.g., within a period T) periodically switches on and off (e.g., the reflection switch 1160) to reflect, then some of the power of the received signal is moved to a set of harmonic frequencies

[0173] Figure 12A are graphs 1200, 1210, 1220 illustrating examples of different signals in the time domain, which may be represented by Figure 10 The different network devices of the system 1000 send and receive. Figure 12A In the graphs 1200, 1210, 1220, the x-axis represents time (eg, in microseconds (μs)) and the y-axis represents normalized amplitude in volts. Specifically, the graph 1200 shows a sine wave (eg, f sinGraph 1210 shows an example of an RF source waveform (e.g., as may be transmitted by RF source 1010) in the form of a 100MHz signal (e.g., T=1 megahertz (MHz)). Graph 1210 shows an example of a waveform (e.g., in the form of a square wave) formed when passive device 1040 periodically switches its reflection on and off (e.g., T=4 μs), which equivalently generates a square wave. Graph 1220 shows an example of a received wave that may be received by reader 1030. The received wave of graph 1220 is the product of the RF source waveform of graph 1200 and the square wave of graph 1210.

[0174] Figure 12B are graphs 1230, 1240, 1250 illustrating examples of different frequency spectra in the frequency domain corresponding to Figure 12A The spectra in graphs 1230, 1240, 1250 can be obtained by transforming the waveforms shown in graphs 1200, 1210, 1220 (e.g., via a Fast Fourier Transform). Figure 12B In the graphs 1230, 1240, 1250, the x-axis represents frequency (eg, in MHz) and the y-axis represents amplitude in volts. Specifically, in the graph 1230, a single carrier frequency f is shown. s In graph 1240, a set of harmonic frequencies is shown. The frequency difference between the harmonic frequencies of graph 1240 may be (±250 kilohertz (kHz)). In graph 1250, the frequency at the carrier frequency f is shown. s The spectrum of graph 1250 may actually contain more harmonic frequencies than those shown in graph 1250. These harmonic frequencies may not be depicted within graph 1250 because their amplitudes are negligible and therefore they may be disregarded.

[0175] As previously mentioned, passive devices can be sensed (eg, located) by using both monostatic sensing and bistatic sensing. Figure 13A 1 is a diagram illustrating an example of a system 1300 for locating a passive device 1320 (e.g., a pUE), where the system 1300 is performing monostatic sensing for positioning. For monostatic sensing, the RF source and reader may be co-located (e.g., both implemented within a network device 1310 (such as a UE or gNB)).

[0176] For example, during operations for performing monostatic sensing of a passive device 1370 (e.g., a pUE), a network device 1310 (e.g., a UE or a gNB) operating as an RF source (e.g., a transmitter) may transmit an RF source waveform (e.g., an RF source signal 1330) to a passive device 1320. The passive device 1320 may reflect the RF source waveform to generate a reflected RF source waveform (e.g., an RF source signal 1340), which may propagate in a direction back toward the network device 1310. The network device 1310 operating as a reader (e.g., a receiver) may receive the reflected RF source waveform (e.g., reflected signal 1340) and then perform positioning processing using the reflected RF source waveform to locate the passive device 1320.

[0177] Figure 13B FIG1 is a diagram illustrating an example of a system 1350 for locating a passive device 1370 (e.g., a pUE), wherein the system 1350 is performing bistatic sensing for positioning. For bistatic sensing, an RF source 1360 (e.g., a gNB or UE) and a reader 1380 (e.g., a UE or gNB) may be separated from each other. For example, during bistatic sensing operations for a passive device 1370 (e.g., a pUE), the RF source 1360 (e.g., a gNB or UE) may transmit an RF source waveform (e.g., an RF source signal 1390) to the passive device 1370. The passive device 1370 may reflect the RF source waveform to generate a reflected RF source waveform (e.g., a reflected signal 1395), which may propagate in a direction toward the reader 1380 (e.g., a UE or gNB). The reader 1380 may receive the reflected RF source waveform and then perform positioning processing using the reflected RF source waveform to locate the passive device 1370.

[0178] In one or more aspects, for locating passive devices using monostatic sensing or bistatic sensing, the received signal at a reader (e.g., a gNB or UE) may consist not only of reflected signals from the passive device, but also of interfering signals. These interfering signals may include a directional (e.g., line-of-sight (LOS)) signal (e.g., for bistatic sensing only) and / or at least one background reflected (e.g., non-line-of-sight (NLOS)) signal. Because the signal strength of the reflected signal from the passive device is typically weaker than the combined signal strength of these interfering signals (e.g., the directional signal plus the background reflected signal), it may be difficult for the reader to fully mitigate the effects of these interfering signals in the time domain. Due to the effects of these interfering signals in the time domain, it may be challenging for the reader to measure the delay of the reflected signal from the passive device and the distance between the passive device and the reader.

[0179] Figure 14Ais a diagram illustrating an example of different signals (e.g., including background reflection signals 1450a, 1450b, 1460a, 1460b) that may be sent and received within a system 1400 performing single-station sensing for locating a passive device 1420 (e.g., a pUE). Figure 14A , system 1400 is shown as including a network device 1410 (eg, including an RF source and a reader), a passive device 1420 (eg, a pUE), and two background objects 1430a, 1430b.

[0180] For monostatic sensing, network device 1410 may send RF source signal 1440a to passive device 1420. RF source signal 1440a may reflect from passive device 1420 to produce reflected signal 1440b that radiates in a direction toward network device 1410. Signal 1440b is the reflected signal from passive device 1420 (e.g., a pUE).

[0181] Signal 1450a may radiate from network device 1410 toward background object 1430a. Signal 1450a may reflect from background object 1430a to produce reflected signal 1450b that radiates in a direction back toward network device 1410. Signal 1460a may radiate from network device 1410 toward background object 1430b. Signal 1460a may reflect from background object 1430b to produce reflected signal 1460b that radiates in a direction back toward network device 1410. These signals 1450a, 1450b, 1460a, 1460b are background reflection (NLOS path) signals.

[0182] Signal 1480a may radiate from network device 1410 to background object 1430b. Signal 1480a may reflect from background object 1430b to produce reflected signal 1480b, which radiates in a direction toward passive device 1420. Reflected signal 1480b may reflect from passive device 1420 to produce reflected signal 1470a, which radiates in a direction toward background object 1430a. Signal 1470a may reflect from background object 1430a to produce reflected signal 1470b, which radiates in a direction back toward network device 1410. Signals 1480a and 1480b form a path from "RF source to background object to pUE," and signals 1470a and 1470b form a path from "pUE to background object to RF source." These signals 1480a, 1480b, 1470a, and 1470b may be ignored (disregarded) because they have low channel gain due to multiple reflections.

[0183] Figure 14Bis a diagram illustrating an example of different signals (e.g., including a directional propagation signal 1465 and background reflection signals 1475a, 1475b) that may be sent and received within a system 1405 performing bistatic sensing for locating a passive device 1425 (e.g., a pUE). Figure 14B , system 1405 is shown as including an RF source 1415 , a reader 1435 , a passive device 1425 (eg, a pUE), and background objects 1445 .

[0184] For bistatic sensing, RF source 1415 may send RF source signal 1455a to passive device 1425. RF source signal 1455a may reflect from passive device 1425 to produce reflected signal 1455b that radiates in a direction toward reader 1435. Signal 1455b is the reflected signal from passive device 1425 (e.g., a pUE).

[0185] Signal 1465 may radiate from RF source 1415 toward (e.g., within a LOS path) a passive device 1435 (e.g., a pUE). The LOS path is from RF source 1415 to reader 1435. Signal 1475a may radiate from RF source 1415 toward background object 1445. Signal 1475a may reflect from background object 1445 to produce a reflected signal 1475b that radiates in a direction toward reader 1435. These signals 1475a, 1475b are background reflection (NLOS path) signals.

[0186] Signal 1485a may radiate from RF source 1415 toward background object 1445. Signal 1485a may reflect from background object 1445 to produce reflected signal 1485b, which radiates in a direction toward passive device 1425. Reflected signal 1485b may reflect from passive device 1425 to produce reflected signal 1485c, which radiates in a direction toward background object 1445. Signal 1485c may reflect from background object 1445 to produce reflected signal 1485d, which radiates in a direction toward reader 1435. Signals 1485a and 1485b form a path from "RF source to pUE to background object," and signals 1485c and 1485d form a path from "pUE to background object to reader." These signals 1485a, 1485b, 1485c, and 1485d are ignored (disregarded) because they have low channel gain due to multiple reflections.

[0187] In one or more aspects, the systems and techniques provide a solution for locating passive devices (e.g., pUEs) based on differential carrier phase estimates at harmonic frequencies. In one or more examples, the systems and techniques allow for locating passive devices by completely mitigating interference (e.g., directional propagation signals plus background reflection signals) using differential carrier phase estimates at harmonic frequencies.

[0188] In one or more examples, in a method for locating a passive device (e.g., a pUE) such as Figure 14A Passive devices 1420 or Figure 14B During operation of the systems and techniques of the IoT device 1425), an RF source (e.g., a gNB or UE) (such as Figure 14A Network device 1410 or Figure 14B The RF source 1415) can send a synchronization signal (or control channel or signal) and send a narrowband RF source waveform (e.g., a sine wave) to the passive device. ) duration. The passive device may monitor the synchronization signal (or control channel or signal) and may synchronize itself (e.g., synchronize the reflection switch of the passive device) according to a synchronization schedule within the synchronization signal (or control channel or signal) (e.g., specified within the information bits). After the passive device has synchronized itself according to the synchronization schedule, the passive device may periodically turn on and off its reflection of the received RF source waveform according to the synchronization schedule. At the reader (e.g., Figure 14A Network device 1410 or Figure 14B After the reader 1435 receives the reflected signal, the reader can estimate the "RF source to pUE to reader" propagation delay based on the differential carrier phase estimation at the harmonic frequency.

[0189] In one or more examples, as mentioned, a synchronization message (e.g., a signaling message or a control message) can be transmitted (e.g., sent) from the RF source to the passive device. In some cases, such as when the RF source and the reader are separated from each other, the RF source can also transmit (e.g., send) the synchronization message to the reader. In one or more examples, the synchronization message can indicate (e.g., include) various parameters. These parameters can include, but are not limited to, the RF source wave duration (e.g., the duration of the RF source sending a sine wave, such as Figure 15 duration of the RF source wave 1525), a synchronization signal (e.g., Figure 15 SS1505) and the time gap between the RF source wave duration (e.g. Figure 15The parameters may include the time gap 1515 on the control channel, the reflection on / off period T, and / or optionally the time domain positioning of the synchronization signal (e.g., without this information, the passive device will always need to monitor the air interface to receive the synchronization signal). In some aspects, these parameters may be included in the control signal sent on the control channel.

[0190] Figure 15 FIG15 is a diagram 1500 illustrating an example of different signals (e.g., waveforms) in the time domain that may be sent and received by different network devices (e.g., RF source 1510, pUE 1520, and reader 1530) of a system for locating passive devices based on differential carrier phase estimation at harmonic frequencies. Figure 15 , the transmitted waveform, reflected waveform, and received waveform are shown for RF source 1510, pUE 1520, and reader 1530. The x-axis of the waveform represents time and is shown to include the timing for synchronization signal 1505, time gap 1515, and duration of RF source wave 1525.

[0191] Specifically, in Figure 15 , a real transmitted wave 1540 (eg, a sine wave) and an equivalent transmitted wave 1550 for an RF source 1510 are shown. Figure 15 Also shown are a true received wave 1560, a periodic reflected on / off waveform (e.g., an equivalent square wave) 1570, and an equivalent reflected wave 1580 for the pUE 1520. Also shown is a true received wave 1590 received by the reader 1530. Also shown is a measurement window 1535 (e.g., for monostatic or bistatic sensing). In one or more examples, the measurement window 1535 should be at least one reflection period later than the start of the RF source duration.

[0192] In one or more examples, if the RF source 1510 and the reader 1530 are co-located (e.g., for monostatic sensing) or have a synchronized clock mechanism (e.g., with a global positioning system (GPS)), the reader 1530 can estimate the propagation delay 1545 of the actual received wave 1590 relative to the equivalent transmitted wave 1550. The reader 1590 can then calculate the distance of the path from the RF source 1510 to the pUE 1520 to the reader 1590 by using the estimated propagation delay 1545. The disclosed method for estimating the propagation delay 1545 will be discussed in detail below.

[0193] As mentioned previously, the received signal (e.g., at the reader) may be a superposition of the directional (LOS path) link, the background reflection (NLOS path) link, and the pUE's reflected link. Therefore, the reader (e.g., receiver) cannot directly estimate the propagation delay based on the time-domain signal. Because only the signal of the pUE's reflected link has harmonic frequency components, the reader can estimate the propagation distance based on the frequency-domain signal at the harmonic frequency to avoid interference.

[0194] Specifically, the reader can estimate the carrier phase variance at the harmonic frequencies. For the equivalent transmitted wave 1550, the maximum power (expressed as )'s two harmonic frequencies (relative to f s ), expressed as and (refer to Figure 16 For the received wave (with a certain delay), the phase value at {f1, f2} can be measured and expressed as and (refer to Figure 16 The received signal can be considered as y(t) = αe jθ x(t-τ), where αe jθ is the complex channel gain. To eliminate the effect of θ, the differential phase estimation between f1 and f2 can be applied, where the estimated propagation delay is in Finally, the estimated propagation distance Where c is the speed of light. The range of measurable distance (without ambiguity) is If T = 4 μs, then d < 600 meters. The measurement accuracy may depend on the sampling rate f sample For example, if f sample =10 / 100 / 1000MHz, then the accuracy is The accuracy (ie, mean square error) may depend on the signal to interference and noise ratio (SINR) at the harmonic frequencies f1, f2. The longer the measurement window, the higher the SINR will be.

[0195] Figure 16 is a diagram 1600 illustrating examples of different signals in the time domain and corresponding spectra in the frequency domain that can be used to determine the propagation delay 1545. Specifically, Figure 16 , a transmitted waveform, a reflected waveform, and a received waveform in the time domain are shown for the RF source 1510 and the reader 1530. The x-axis of the waveform represents time.

[0196] Specifically, in Figure 16, an equivalent transmitted wave 1550 for the RF source 1510 is shown. Figure 16 Also shown are a real received wave of a directional transmission (LOS path) link 1610 , a real received wave of a background reflection (NLOS path) link 1620 , and a real received wave 1590 (eg, of a reflection link of a pUE), all of which are received by the reader 1530 .

[0197] Figure 16 Also shown are graphs 1630 and 1640 illustrating examples of different frequency spectra in the frequency domain, which correspond to the equivalent transmitted wave 1550, the actual received wave of the directional transmission (LOS path) link 1610, the actual received wave of the background reflection (NLOS path) link 1620, and the actual received wave 1590 (e.g., of the reflection link of the pUE). Graph 1630 shows the phase values ​​for the equivalent transmitted wave. and Graph 1640 shows the phase values and

[0198] In one or more aspects, the reflection delay (e.g., group delay) of a passive device (e.g., pUE) can be considered. In one or more examples, after estimating the "RF source to pUE to reader" distance, if the pUE has a reflection delay (e.g., estimated delay = "RF source to pUE to reader" path delay plus pUE reflection delay), a differential positioning method can be applied.

[0199] In one or more examples, for a differential positioning method, two or more readers may first estimate delay values. Then, the difference between their estimated delay values ​​may represent the path delay difference. The pUE's position may lie within the hyperbola corresponding to the two readers.

[0200] If the pUE has no (or negligible) reflection delay (e.g., estimated delay = "RF source to pUE to reader" path delay), the pUE's position can be located within a circular curve (e.g., for monostatic sensing) or an elliptical curve (e.g., for bistatic sensing) corresponding to the reader. In one or more examples, when the pUE has a reflection delay (e.g., group delay), the reader can know the reflection delay in advance (e.g., indicated by the pUE during its connection establishment process).

[0201] Figure 17 FIG17 is a diagram 1700 illustrating an example of different signals in the time domain that can be used to determine the reflection delay (group delay) for a passive device (eg, pUE). Figure 17, there are shown transmitted waveforms, reflected waveforms, and received waveforms for an RF source 1710, a pUE 1720, and a reader 1730. The x-axis of the waveforms represents time.

[0202] Specifically, in Figure 17 , a real transmitted wave 1740 (eg, a sine wave) and an equivalent transmitted wave 1750 for an RF source 1710 are shown. Figure 17 Also shown are a real received wave 1760, a periodic reflected on / off waveform (e.g., an equivalent square wave) 1770, and an equivalent reflected wave 1780 for a pUE 1720. Also shown is a real received wave 1790 received by a reader 1730. Also shown is a measurement window 1705 (e.g., for monostatic or bistatic sensing). In one or more examples, the measurement window 1705 should be at least one reflection period later than the start of the RF source duration.

[0203] Figure 17 1700 depicts the effect of reflection delay (eg, group delay) that may be caused by clock synchronization errors of a pUE 1720. The equivalent reflected wave 1780 at the pUE 1720 is changed to in Equivalent to the equivalent transmitted wave 1750.

[0204] In one or more examples, the reader 1730 can still use a form of the original equivalent transmitted wave 1750 to estimate the delay 1735. It can be incorporated into the channel response. The estimated delay 1735 may include the propagation delay 1725 and the group delays 1715a, 1715b.

[0205] Figure 18 is a flow chart illustrating an example of a process 1800 for wireless communication utilizing a method for locating a passive device (e.g., a network device) based on differential carrier phase estimation at harmonic frequencies. Process 1800 may be performed by a network device or by a component or system (e.g., a chipset) of a network device. The network device may be a UE (e.g., a mobile device such as a mobile phone, a network-connected wearable device such as a watch, an extended reality device such as a virtual reality (VR) device or an augmented reality (AR) device, a vehicle or a component or system of a vehicle, or other type of UE), a base station (e.g., a gNB, an eNB, or other base station), a portion of a base station (e.g., a CU, DU, RU, or other portion of a base station with a disaggregated architecture), or other type of network device. The operations of process 1800 may be implemented as a processor (e.g., a processor) on one or more processors (e.g., Figure 20In addition, the sending and receiving of signals by the wireless communication device in process 1800 can be implemented, for example, through one or more antennas and / or one or more transceivers (e.g., wireless transceivers).

[0206] At block 1810, a network device (or a component or system thereof) may receive a message including a packet from a passive network device (e.g., Figure 14A and / or Figure 14B In some cases, the one or more interfering signals include at least one of one or more directly propagated signals or one or more background reflected signals, such as Figure 14A and Figure 14B described.

[0207] At block 1820, the network device (or a component or system thereof) may determine the propagation delay based on the differential carrier phase estimate at the harmonic frequencies of the received signal in the frequency domain, such as with respect to Figure 15 and / or Figure 16 In some cases, the propagation delay spans from the time of the start of the measurement window to the time of the first peak in the received signal after the time of the start of the measurement window (eg, propagation delay 1545 based on measurement window 1535).

[0208] At block 1830, the network device (or its components or systems) may use the propagation delay to determine the location of the passive network device. In some cases, the network device (or its components or systems) may determine the reflection delay of the passive network device, such as with respect to Figure 17 As described. In such cases, the network device (or its component or system) may further determine the location of the passive network device based on the reflection delay of the passive network device. In some aspects, the network device (or its component or system) may determine the distance of the passive network device based on the duration of the propagation delay. In such aspects, the network device (or its component or system) may determine the location of the passive network device based on the distance. In some cases, the network device (or its component or system) configured to perform process 1800 may be a receiver that can perform bistatic sensing. For example, the network device (or its component or system) may determine the location of the passive network device based on bistatic sensing of the passive network device.

[0209] In some aspects, a network device (or a component or system thereof) may receive a synchronization signal or a control signal (e.g., on a control channel) that includes a time gap between transmissions of the synchronization signal and a source signal, a duration of the source signal, and / or a reflection switching period for a passive network device.

[0210] Figure 19 is a flow chart illustrating an example of a process 1900 for wireless communication utilizing a method for locating a passive device (e.g., a network device) based on differential carrier phase estimation at harmonic frequencies. Process 1900 may be performed by a network device or by a component or system (e.g., a chipset) of a network device. The network device may be a UE (e.g., a mobile device such as a mobile phone, a network-connected wearable device such as a watch, an extended reality device such as a virtual reality (VR) device or an augmented reality (AR) device, a vehicle or a component or system of a vehicle, or other type of UE), a base station (e.g., a gNB, an eNB, or other base station), a portion of a base station (e.g., a CU, DU, RU, or other portion of a base station with a disaggregated architecture), or other type of network device. The operations of process 1900 may be implemented as a processor (e.g., a processor) on one or more processors (e.g., Figure 20 In addition, the sending and receiving of signals by the wireless communication device in process 1900 can be implemented, for example, through one or more antennas and / or one or more transceivers (e.g., wireless transceivers).

[0211] At block 1910, a network device (or a component thereof) may send a source signal to a passive network device (e.g., Figure 14A and / or Figure 14B For example, a network device (or a component thereof) may send Figure 15 RF source 1510.

[0212] At block 1920, the network device (or a component thereof) may receive a signal including a reflected signal and one or more interfering signals. The reflected signal is generated by the source signal being reflected from the passive network device (e.g., Figure 14B shown).

[0213] At block 1930, the network device (or a component thereof) may determine the propagation delay based on the differential carrier phase estimate at the harmonic frequencies of the received signal in the frequency domain, such as with respect to Figure 15 and / or Figure 16 As previously described, the propagation delay may span from the time of the start of the measurement window to the time of the first peak in the received signal after the time of the start of the measurement window (eg, propagation delay 1545 based on measurement window 1535).

[0214] At block 1940, the network device (or a component thereof) may use the propagation delay to determine the location of the passive network device. In some cases, the network device (or a component or system thereof) may determine the reflection delay of the passive network device, such as with respect to Figure 17In such cases, the network device (or its components or systems) may further determine the location of the passive network device based on the reflection delay of the passive network device. In some cases, the network device (or its components or systems) configured to perform process 1900 may be configured to perform single-station sensing. For example, the network device (or its components) may determine the location of the passive network device based on single-station sensing of the passive network device.

[0215] In some aspects, the network device (or its components) can send a synchronization signal to the passive network device. As described herein, the synchronization signal and / or control signal (e.g., on a control channel). The synchronization signal and / or control signal may include at least one of a time gap between the transmission of the synchronization signal and the source signal, a duration of the source signal, a reflection switching cycle for the passive network device, and / or a time domain positioning of the synchronization signal. In some cases, the reflection signal is periodically reflected from the passive network device according to a reflection switching cycle specified in the synchronization signal or the control signal.

[0216] The network device may include various components, such as one or more input devices, one or more output devices, one or more processors, one or more microprocessors, one or more microcomputers, one or more cameras, one or more sensors, one or more receivers, transmitters and / or transceivers and / or other components configured to perform the steps of the processes described herein.

[0217] Configured to execute Figure 18 Process 1800 and / or Figure 19 The components of the network device of process 1900 may be implemented in circuitry. For example, the components may include and / or be implemented using electronic circuitry or other electronic hardware that may include one or more programmable electronic circuits (e.g., a microprocessor, a graphics processing unit (GPU), a digital signal processor (DSP), a central processing unit (CPU), and / or other suitable electronic circuitry) and / or may include and / or be implemented using computer software, firmware, or any combination thereof for performing the various operations described herein.

[0218] Process 1800 and process 1900 are illustrated as a logical flow diagram, the operations of which represent a sequence of operations that can be implemented in hardware, computer instructions, or a combination thereof. In the context of computer instructions, each operation represents a computer-executable instruction stored on one or more computer-readable storage media that, when executed by one or more processors, performs the described operation. Generally speaking, computer-executable instructions include routines, programs, objects, components, data structures, etc. that perform specific functions or implement specific data types. The order in which the operations are described is not intended to be construed as a limitation, and any number of the described operations may be combined in any order and / or in parallel to implement the process.

[0219] In addition, process 1800, process 1900, and / or other processes described herein can be executed under the control of one or more computer systems configured with executable instructions and can be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) that is executed on one or more processors, through hardware, or a combination thereof. As noted above, the code can be stored on a computer-readable or machine-readable storage medium, for example, in the form of a computer program comprising multiple instructions that can be executed by one or more processors. The computer-readable or machine-readable storage medium can be non-transitory.

[0220] Figure 20 is a block diagram illustrating an example of a computing system 2000 that may be employed by the disclosed systems and techniques for locating passive devices (e.g., network devices) based on differential carrier phase estimation at harmonic frequencies. Specifically, Figure 20 An example of a computing system 2000 is illustrated, which can be any computing device, for example, constituting an internal computing system, a remote computing system, a camera, or any component thereof, wherein the components of the system communicate with each other using a connection 2005. Connection 2005 can be a physical connection using a bus, or a direct connection to processor 2010, such as in a chipset architecture. Connection 2005 can also be a virtual connection, a networked connection, or a logical connection.

[0221] In some aspects, computing system 2000 is a distributed system, wherein the functionality described in this disclosure may be distributed within a data center, multiple data centers, a peer-to-peer network, etc. In some aspects, one or more of the described system components represent a plurality of such components, each of which performs some or all of the functionality of the described component. In some aspects, each component may be a physical or virtual device.

[0222] The example system 2000 includes at least one processing unit (CPU or processor) 2010 and connections 2005 that communicatively couple various system components including system memory 2015, such as read-only memory (ROM) 2020 and random access memory (RAM) 2025, to the processor 2010. The computing system 2000 may include a cache 2012 of high-speed memory directly connected to, in close proximity to, or integrated as part of the processor 2010.

[0223] Processor 2010 may include any general-purpose processor and hardware or software services, such as services 2032, 2034, and 2036 stored in storage device 2030, configured to control processor 2010 as well as a dedicated processor where software instructions are incorporated into the actual processor design. Processor 2010 may essentially be a completely independent computing system containing multiple cores or processors, buses, memory controllers, caches, etc. Multi-core processors may be symmetric or asymmetric.

[0224] To enable user interaction, the computing system 2000 includes an input device 2045 that can represent any number of input mechanisms, such as a microphone for voice, a touch-sensitive screen for gesture or graphical input, a keyboard, a mouse, motion input, voice, etc. The computing system 2000 may also include an output device 2035, which can be one or more of a plurality of output mechanisms. In some cases, a multimodal system can enable a user to provide multiple types of input / output to communicate with the computing system 2000.

[0225] The computing system 2000 may include a communication interface 2040, which generally governs and manages user input and system output. The communication interface may perform or facilitate receiving and / or sending wired or wireless communications using wired and / or wireless transceivers, including using audio jacks / plugs, microphone jacks / plugs, Universal Serial Bus (USB) ports / plugs, Apple TM Lightning TM Ports / plugs, Ethernet ports / plugs, fiber optic ports / plugs, dedicated wired ports / plugs, 3G, 4G, 5G and / or other cellular data network wireless signal transmission, Bluetooth TM Wireless signal transmission, Bluetooth TM Low energy (BLE) wireless signal transmission, IBEACON TMWireless signal transmission, radio frequency identification (RFID) wireless signal transmission, near field communication (NFC) wireless signal transmission, dedicated short range communication (DSRC) wireless signal transmission, 802.11 Wi-Fi wireless signal transmission, wireless local area network (WLAN) signal transmission, visible light communication (VLC), Worldwide Interoperability for Microwave Access (WiMAX), infrared (IR) communication wireless signal transmission, public switched telephone network (PSTN) signal transmission, integrated services digital network (ISDN) signal transmission, ad hoc network signal transmission, radio wave signal transmission, microwave signal transmission, infrared signal transmission, visible light signal transmission, ultraviolet light signal transmission, wireless signal transmission along the electromagnetic spectrum, or some combination thereof.

[0226] Communication interface 2040 may also include one or more ranging sensors (e.g., LIDAR sensors, laser rangefinders, RF radars, ultrasonic sensors, and infrared (IR) sensors) configured to collect data and provide measurements to processor 2010, whereby processor 2010 may be configured to perform the determinations and calculations required to obtain various measurements of the one or more ranging sensors. In some examples, the measurements may include time of flight, wavelength, azimuth, elevation, distance, linear velocity, and / or angular velocity, or any combination thereof. Communication interface 2040 may also include one or more Global Navigation Satellite System (GNSS) receivers or transceivers for determining the location of computing system 2000 based on one or more signals received from one or more satellites associated with one or more GNSS systems. GNSS systems include, but are not limited to, the United States' GPS, Russia's Global Navigation Satellite System (GLONASS), China's BeiDou Navigation Satellite System (BDS), and Europe's Galileo GNSS. There is no restriction to operating on any particular hardware arrangement, and thus the underlying features herein may be readily substituted for improved hardware or firmware arrangements as they are developed.

[0227] The storage device 2030 may be a non-volatile and / or non-transitory and / or computer-readable memory device and may be a hard disk or other type of computer-readable medium that can store data that can be accessed by a computer, such as a magnetic cassette, a flash memory card, a solid-state memory device, a digital versatile disk, a cassette, a floppy disk, a floppy disk, a hard disk, a magnetic tape, a magnetic stripe / magnetic stripe, any other magnetic storage medium, flash memory, a memristor memory, any other solid-state memory, a compact disc read-only memory (CD-ROM) optical disc, a rewritable compact disc (CD) optical disc, a digital video disc (DVD) optical disc, a Blu-ray disc (BDD) optical disc, a holographic optical disc, another optical medium, a secure digital (SD) card, a micro secure digital (microSD) card, card, a smart card chip, an EMV chip, a subscriber identity module (SIM) card, a mini / micro / nano / pico SIM card, another integrated circuit (IC) chip / card, a random access memory (RAM), a static RAM (SRAM), a dynamic RAM (DRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash EPROM (FLASH EPROM), a cache memory (e.g., a level 1 (L1) cache, a level 2 (L2) cache, a level 3 (L3) cache, a level 4 (L4) cache, a level 5 (L5) cache, or other (L#) cache), a resistive random access memory (RRAM / ReRAM), a phase change memory (PCM), a spin transfer torque RAM (STT-RAM), another memory chip or cartridge, and / or a combination thereof.

[0228] Storage device 2030 may include software services, servers, services, etc., which, when the code defining such software is executed by processor 2010, causes the system to perform functions. In some aspects, hardware services that perform specific functions may include software components for performing functions stored in a computer-readable medium connected to the necessary hardware components (such as processor 2010, connection 2005, output device 2035, etc.). The term "computer-readable medium" includes, but is not limited to, portable or non-portable storage devices, optical storage devices, and various other media capable of storing, containing, or carrying instructions and / or data. Computer-readable media may include non-transient media in which data can be stored and does not include carrier waves and / or transient electronic signals propagated wirelessly or over a wired connection. Examples of non-transient media may include, but are not limited to, disks or tapes, optical storage media (such as compact discs (CDs) or digital versatile discs (DVDs)), flash memory, memory, or memory devices. Computer readable media can store thereon code and / or machine executable instructions, which can represent any combination of a process, function, subroutine, program, routine, subroutine, module, software package, category, or instruction, data structure, or program statement. A code segment can be coupled to another code segment or a hardware circuit by transmitting and / or receiving information, data, independent variables, parameters, or memory contents. Information, independent variables, parameters, data, etc. can be transmitted, forwarded, or sent via any suitable means, including memory sharing, message passing, token passing, network transmission, etc.

[0229] Specific details are provided in the description above to provide a thorough understanding of the various aspects and examples provided herein, but those skilled in the art will recognize that the application is not limited thereto. Thus, although the exemplary aspects of the present application have been described in detail herein, it is to be understood that each inventive concept can be implemented and adopted in various other ways, and the appended claims are not intended to be interpreted as including these variations unless limited by the prior art. The various features and aspects of the application described above can be used individually or in combination. In addition, without departing from the broader scope of this specification, each aspect can be used in any number of environments and applications beyond the environment and application described herein. Therefore, the description and the accompanying drawings should be considered as illustrative rather than restrictive. For illustrative purposes, each method is described in a specific order. It should be understood that, in alternative aspects, each method can be performed in a different order than described.

[0230] For clarity of explanation, in some cases, the present technology can be presented as including separate functional blocks, which include devices, device components, steps or routines in the method embodied in software or a combination of hardware and software. Additional components other than those components shown in the drawings and / or described herein can be used. For example, circuits, systems, networks, processes and other components can be shown as components in block diagram form to avoid confusing these aspects in unnecessary details. In other cases, well-known circuits, processes, algorithms, structures and techniques can be shown without unnecessary details to avoid confusing various aspects.

[0231] In addition, it will be appreciated by those skilled in the art that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the various aspects disclosed herein can be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints proposed for the entire system. Those skilled in the art can implement the described functions in different ways for each specific application, but such specific implementation decisions should not be interpreted as causing departure from the scope of this disclosure.

[0232] Various aspects may be described above as processes or methods, which may be depicted as flow charts, flowcharts, data flow diagrams, structure diagrams, or block diagrams. Although a flow chart may describe operations as a sequential process, many of the operations may be performed in parallel or concurrently. Furthermore, the order of the operations may be rearranged. A process is terminated when its operations are completed, but a process may have additional steps not included in the accompanying figures. A process may correspond to a method, function, procedure, subroutine, subprogram, etc. When a process corresponds to a function, termination of the process may correspond to the function returning to the calling function or the main function.

[0233] The processes and methods according to the examples described above can be implemented using stored computer-executable instructions or computer-executable instructions otherwise obtained from a computer-readable medium. Such instructions may include, for example, instructions and data that cause or otherwise configure a general-purpose computer, a special-purpose computer, or a processing device to perform a certain function or group of functions. Portions of the computer resources used may be accessible over a network. The computer-executable instructions may be, for example, binary, intermediate format instructions such as assembly language, firmware, source code. Examples of computer-readable media that can be used to store instructions, information used, and / or information created during the methods according to the described examples include magnetic or optical disks, flash memory, USB devices with non-volatile memory, networked storage devices, and the like.

[0234] In some aspects, computer readable storage devices, media, and memories may include cables or wireless signals containing bit streams, etc. However, when referred to, non-transitory computer readable storage media specifically excludes media such as power consumption, carrier signals, electromagnetic waves, and signals themselves.

[0235] Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description may, in some cases, be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof, depending in part on the specific application, in part on the desired design, in part on the corresponding technology, etc.

[0236] The various illustrative logic blocks, modules, and circuits described in conjunction with the various aspects disclosed herein may be implemented or executed using hardware, software, firmware, middleware, microcode, hardware description language, or any combination thereof, and may be implemented in any of a variety of form factors. When implemented in software, firmware, middleware, or microcode, program code or code segments (e.g., a computer program product) for performing the necessary tasks may be stored in a computer-readable or machine-readable medium. A processor may perform the necessary tasks. Examples of form factors include: laptop computers, smartphones, mobile phones, tablet devices, or other small form factor personal computers, personal digital assistants, rack-mounted devices, stand-alone devices, and the like. The functionality described herein may also be embodied in peripheral devices or add-in cards. By way of further example, such functionality may also be implemented on circuit boards in different chips or different processes executed on a single device.

[0237] Instructions, media for conveying such instructions, computing resources for executing them, and other structures for supporting such computing resources are example means for providing the functionality described in this disclosure.

[0238] The techniques described herein may also be implemented in electronic hardware, computer software, firmware, or any combination thereof. Such techniques may be implemented in any of a variety of devices, such as general-purpose computers, wireless communication devices, or integrated circuit devices with multiple uses, including applications in wireless communication devices and other devices. Any features described as modules or components may be implemented together in an integrated logic device or separately as discrete but interoperable logic devices. If implemented in software, the techniques may be implemented at least in part by a computer-readable data storage medium comprising program code, which includes instructions that, when executed, perform one or more of the methods, algorithms, and / or operations described above. The computer-readable data storage medium may form part of a computer program product, which may include packaging materials. The computer-readable medium may include a memory or data storage medium, such as a random access memory (RAM) (such as synchronous dynamic random access memory (SDRAM)), a read-only memory (ROM), a non-volatile random access memory (NVRAM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic or optical data storage medium, or the like. Additionally or alternatively, the technology may be implemented at least in part by a computer-readable communication medium that carries or communicates program code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer, such as a propagated signal or wave.

[0239] The program code may be executed by a processor, which may include one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Such a processor may be configured to perform any of the techniques described in this disclosure. A general-purpose processor may be a microprocessor; however, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. Therefore, the term "processor" as used herein may refer to any of the foregoing structures, any combination of the foregoing structures, or any other structure or device suitable for implementing the techniques described herein.

[0240] It should be understood by those skilled in the art that the less than ("<") and greater than (">") symbols or terms used herein may be replaced by less than or equal to ("≤") and greater than or equal to ("≥") symbols, respectively, without departing from the scope of this specification.

[0241] Where a component is described as being “configured to” perform certain operations, such configuration may be achieved, for example, by designing electronic circuits or other hardware to perform the operations, by programming programmable electronic circuits (e.g., a microprocessor or other suitable electronic circuits) to perform the operations, or any combination thereof.

[0242] The phrases “coupled to” or “communicatively coupled to” refer to any component being physically connected directly or indirectly to another component, and / or any component being in communication, directly or indirectly, with another component (e.g., connected to the other component via a wired or wireless connection and / or other suitable communication interface).

[0243] Claim language or other language reciting "at least one of" a set and / or "one or more of" a set indicates that one member of the set or multiple members of the set (in any combination) satisfies the claim. For example, claim language reciting "at least one of A and B" or "at least one of A or B" means A, B, or A and B. In another example, claim language reciting "at least one of A, B, and C" or "at least one of A, B, or C" means A, B, C, or A and B, or A and C, or B and C, or A, B, and C. The language "at least one of" a set and / or "one or more of" a set does not limit the set to the items listed in the set. For example, claim language reciting "at least one of A and B" or "at least one of A or B" may mean A, B, or A and B, and may additionally include items not listed in the set of A and B.

[0244] Illustrative aspects of the present disclosure include:

[0245] Aspect 1. A network device for wireless communication, the network device comprising: at least one memory; and at least one processor, the at least one processor being coupled to the at least one memory and configured to: receive a signal comprising a reflected signal reflected from a passive network device and one or more interfering signals; determine a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in a frequency domain; and determine a location of the passive network device using the propagation delay.

[0246] Aspect 2. The network device according to aspect 1, wherein the network device is one of a user equipment (UE) or a base station.

[0247] Aspect 3. The network device according to any one of aspects 1 or 2, wherein the network device is a reader device.

[0248] Aspect 4. The network device according to any one of aspects 1 to 3, wherein the one or more interfering signals include at least one of one or more directly propagated signals or one or more background reflected signals.

[0249] Aspect 5. The network device according to any one of aspects 1 to 4, wherein the passive network device is one of a passive user equipment (UE), a tag, an ambient backscatter device, or a backscatter device.

[0250] Aspect 6. The network device according to any one of aspects 1 to 5, wherein the reflected signal is periodically reflected from the passive network device.

[0251] Aspect 7. The network device according to any one of aspects 1 to 6, wherein the at least one processor is configured to determine a reflection delay of the passive network device.

[0252] Aspect 8. The network device according to aspect 7, wherein the at least one processor is configured to determine the location of the passive network device further based on the reflection delay of the passive network device.

[0253] Aspect 9. The network device of any one of aspects 1 to 8, wherein the at least one processor is configured to determine the location of the passive network device based on bistatic sensing of the passive network device.

[0254] Aspect 10. The network device of any one of aspects 1 to 9, wherein the at least one processor is configured to: determine a distance of the passive network device based on a duration of the propagation delay; and determine the location of the passive network device based on the distance.

[0255] Aspect 11. The network device of any one of aspects 1 to 10, wherein the propagation delay spans from a time of a start of a measurement window to a time of a first peak in the received signal after the time of the start of the measurement window.

[0256] Aspect 12. A network device according to any one of Aspects 1 to 11, wherein the at least one processor is configured to receive a synchronization signal or a control signal, the synchronization signal or the control signal including at least one of a time gap between the transmission of the synchronization signal and a source signal, a duration of the source signal, or a reflection switching period for the passive network device.

[0257] Aspect 13. A method for wireless communication at a network device, the method comprising: receiving, by the network device, a signal comprising a reflected signal reflected from a passive network device and one or more interfering signals; determining, by the network device, a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and determining, by the network device, a location of the passive network device using the propagation delay.

[0258] Aspect 14. The method according to aspect 13, wherein the one or more interfering signals include at least one of one or more directly propagated signals or one or more background reflected signals.

[0259] Aspect 15. The method according to any one of Aspects 13 or 14, further comprising determining, by the network device, a reflection delay of the passive network device, wherein the position of the passive network device is further determined based on the reflection delay of the passive network device.

[0260] Aspect 16. The method according to any one of aspects 13 to 15, wherein the location of the passive network device is determined based on bistatic sensing of the passive network device.

[0261] Aspect 17. The method according to any one of aspects 13 to 16, further comprising: determining a distance of the passive network device based on the duration of the propagation delay; and determining the location of the passive network device based on the distance.

[0262] Aspect 18. The method according to any one of aspects 13 to 17, wherein the propagation delay spans from the time of the start of a measurement window to the time of a first peak in the received signal after the time of the start of the measurement window.

[0263] Aspect 19. The method according to any one of Aspects 13 to 18, further comprising receiving a synchronization signal or a control signal, wherein the synchronization signal or the control signal includes at least one of a time gap between the transmission of the synchronization signal and the source signal, a duration of the source signal, or a reflection switching period for the passive network device.

[0264] Aspect 20. A network device for wireless communication, the network device comprising: at least one memory; and at least one processor, the at least one processor being coupled to the at least one memory and configured to: send a source signal to a passive network device; receive a signal comprising a reflected signal and one or more interference signals, wherein the reflected signal is generated by the source signal being reflected from the passive network device; determine a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and determine a location of the passive network device using the propagation delay.

[0265] Aspect 21. The network device according to aspect 20, wherein the network device is one of a UE or a base station.

[0266] Aspect 22. The network device according to any one of aspects 20 or 21, wherein the network device is one of a radio frequency (RF) source and a reader.

[0267] Aspect 23. A network device according to any one of Aspects 20 to 22, wherein the at least one processor is configured to send a synchronization signal to the passive network device, and wherein the synchronization signal includes at least one of a time gap between the transmission of the synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

[0268] Aspect 24. A network device according to any one of Aspects 20 to 23, wherein the at least one processor is configured to send a control signal, the control signal including at least one of a time gap between the transmission of a synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

[0269] Aspect 25. The network device according to any one of aspects 20 to 24, wherein the reflected signal is periodically reflected from the passive network device according to a reflection switching period specified in a synchronization signal or a control signal.

[0270] Aspect 26. The network device of any one of aspects 20 to 25, wherein the at least one processor is configured to determine the location of the passive network device based on single-station sensing of the passive network device.

[0271] Aspect 27. A method for wireless communication at a network device, the method comprising: sending, by the network device, a source signal to a passive network device; receiving, by the network device, a signal comprising a reflected signal and one or more interference signals, wherein the reflected signal is generated by reflection of the source signal from the passive network device; determining, by the network device, a propagation delay based on a differential carrier phase estimate at a harmonic frequency of the received signal in the frequency domain; and determining, by the network device, a position of the passive network device using the propagation delay.

[0272] Aspect 28. The method according to Aspect 27 further includes sending a synchronization signal by the network device to the passive network device, wherein the synchronization signal includes at least one of a time gap between the transmission of the synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

[0273] Aspect 29. The method according to any one of Aspects 27 or 28 further includes sending a control signal by the network device, wherein the control signal includes at least one of a time gap between the sending of a synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

[0274] Aspect 30. The method according to any one of aspects 27 to 29, wherein the reflected signal is periodically reflected from the passive network device according to a reflection switching period specified in a synchronization signal or a control signal.

[0275] Aspect 31. The method according to any one of aspects 27 to 30, wherein the location of the passive network device is determined based on single-station sensing of the passive network device.

[0276] Aspect 32. A non-transitory computer-readable medium having instructions stored thereon, the instructions, when executed by at least one processor, causing the at least one processor to perform the operations of any one of aspects 13 to 19.

[0277] Aspect 33. An apparatus for wireless communication, the apparatus comprising one or more means for performing the operations of any one of aspects 13 to 19.

[0278] Aspect 34. A non-transitory computer-readable medium having instructions stored thereon, the instructions, when executed by at least one processor, causing the at least one processor to perform the operations of any one of aspects 27 to 31.

[0279] Aspect 35. An apparatus for wireless communication, the apparatus comprising one or more means for performing the operations of any one of aspects 27 to 31.

[0280] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically stated otherwise, but rather "one or more."

Claims

1. A network device for wireless communication, the network device comprising: at least one memory; and at least one processor coupled to the at least one memory and configured to: receiving a signal including a reflected signal reflected from a passive network device and one or more interfering signals; determining propagation delay based on differential carrier phase estimates at harmonic frequencies of the received signal in the frequency domain; and The propagation delay is used to determine a location of the passive network device. 2 . The network device of claim 1 , wherein the network device is one of a user equipment (UE) or a base station. The network device of claim 1 , wherein the network device is a reader device. 4 . The network device of claim 1 , wherein the one or more interfering signals comprise at least one of one or more directly propagated signals or one or more background reflected signals.

5. The network device of claim 1, wherein the passive network device is one of a passive user equipment (UE), a tag, an ambient backscatter device, or a backscatter device. The network device according to claim 1 , wherein the reflected signal is periodically reflected from the passive network device.

7. The network device of claim 1, wherein the at least one processor is configured to determine a reflected delay of the passive network device.

8. The network device of claim 7, wherein the at least one processor is configured to determine the location of the passive network device further based on the reflection delay of the passive network device.

9. The network device of claim 1, wherein the at least one processor is configured to determine the location of the passive network device based on bistatic sensing of the passive network device.

10. The network device of claim 1 , wherein the at least one processor is configured to: determining a distance of the passive network device based on a duration of the propagation delay; and The location of the passive network device is determined based on the distance.

11. The network device of claim 1, wherein the propagation delay spans from a time of a start of a measurement window to a time of a first peak in the received signal after the time of the start of the measurement window.

12. The network device of claim 1 , wherein the at least one processor is configured to receive a synchronization signal or a control signal, the synchronization signal or the control signal comprising at least one of a time gap between transmission of the synchronization signal and a source signal, a duration of the source signal, or a reflective switching period for the passive network device.

13. A method for wireless communication at a network device, the method comprising: receiving, by the network device, a signal comprising a reflected signal reflected from a passive network device and one or more interfering signals; determining, by the network device, a propagation delay based on differential carrier phase estimates at harmonic frequencies of the received signal in the frequency domain; as well as The propagation delay is used by the network device to determine a location of the passive network device.

14. The method of claim 13, wherein the one or more interfering signals comprise at least one of one or more directly propagated signals or one or more background reflected signals.

15. The method of claim 13, further comprising determining, by the network device, a reflection delay of the passive network device, wherein the position of the passive network device is further determined based on the reflection delay of the passive network device.

16. The method of claim 13, wherein the location of the passive network device is determined based on bistatic sensing of the passive network device.

17. The method according to claim 13, further comprising: determining a distance of the passive network device based on a duration of the propagation delay; as well as The location of the passive network device is determined based on the distance.

18. The method of claim 13, wherein the propagation delay spans from a time of a start of a measurement window to a time of a first peak in the received signal after the time of the start of the measurement window.

19. A network device for wireless communication, the network device comprising: at least one memory; and at least one processor coupled to the at least one memory and configured to: Sends source signals to passive network devices; receiving a signal comprising a reflected signal and one or more interfering signals, wherein the reflected signal is generated by the source signal being reflected from the passive network device; determining propagation delay based on differential carrier phase estimates at harmonic frequencies of the received signal in the frequency domain; and The propagation delay is used to determine a location of the passive network device.

20. The network device of claim 19, wherein the network device is one of a UE or a base station.

21. The network device of claim 19, wherein the network device is one of a radio frequency (RF) source and a reader.

22. The network device of claim 19, wherein the at least one processor is configured to send a synchronization signal to the passive network device, and wherein the synchronization signal comprises at least one of a time gap between the transmission of the synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

23. The network device of claim 19, wherein the at least one processor is configured to send a control signal comprising at least one of a time gap between transmission of a synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

24. According to the claim 19 The network device, wherein the reflected signal is periodically reflected from the passive network device according to a reflection switching period specified in a synchronization signal or a control signal.

25. The network device of claim 19, wherein the at least one processor is configured to determine the location of the passive network device based on single-station sensing of the passive network device.

26. A method for wireless communication at a network device, the method comprising: The network device sends the source signal to the passive network device; receiving, by the network device, a signal comprising a reflected signal and one or more interference signals, wherein the reflected signal is generated by the source signal being reflected from the passive network device; determining, by the network device, a propagation delay based on differential carrier phase estimates at harmonic frequencies of the received signal in the frequency domain; as well as The propagation delay is used by the network device to determine a location of the passive network device.

27. The method of claim 26, further comprising sending, by the network device, a synchronization signal to the passive network device, wherein the synchronization signal comprises at least one of a time gap between the transmission of the synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

28. The method of claim 26, further comprising sending a control signal by the network device, the control signal comprising at least one of a time gap between sending a synchronization signal and the source signal, a duration of the source signal, a reflection switching period for the passive network device, or a time domain positioning of the synchronization signal.

29. The method of claim 26, wherein the reflected signal is periodically reflected from the passive network device according to a reflection switching period specified in a synchronization signal or a control signal.

30. The method of claim 26, wherein the location of the passive network device is determined based on single-station sensing of the passive network device.

Images