Method, system and apparatus for low power mode collaborative synchronization

Abstract

Some embodiments of the present invention relate to using chirp signals in a synchronization process of a wireless communication system. For synchronization purposes, a user equipment (UE) receives and processes a synchronous chirp signal in a low power mode. By using the synchronous chirp signal, low-complexity processing can be realized in the radio frequency (RF) analog domain. It is well known that processing in the RF analog domain may reduce power consumption relative to processing in the baseband digital domain. Reduction of beam scanning at the UE may also be shown to reduce power consumption at the UE and reduce processing complexity. After the UE interacts with the device transmitting the synchronization signal, the device transmitting the synchronization signal may report measurements to the network. Due to receiving the measurement report, the device may be enabled to estimate the timing advance of the UE.

Description

Technical Field

[0001] The present invention relates generally to wireless communications and, in particular embodiments, to synchronization between devices in a wireless communication network and, even more particularly, to coordinated synchronization of devices operating in a low power mode. Background Art

[0002] The known fifth generation (5G) new radio (NR) mobile wireless communication standard includes the definition of operating "states" or "modes" in which user equipment (UE) can operate. When the UE operates in one of two states (one state is called "IDLE" and the other state is called "INACTIVE"), the UE can be understood to be operating in a low power mode. In each of these two states, the UE shuts down circuits that are considered unnecessary. The shutting down of such circuits can be shown to successfully enable the UE to reduce power consumption. Conversely, the UE can also operate in a "CONNECTED" state, where power consumption is not as important.

[0003] The standards for the sixth generation (6G) of mobile wireless communications are currently being developed. Given the success of the low power mode of UEs that follow the 5G NR standard, it is expected that similar low power modes will become part of the 6G standard. In addition, it seems likely that new low power modes will be defined in the 6G standard. It can be expected that the power consumption limits of at least some of the new low power modes are more stringent than the power consumption limits of the low power modes defined in the 5G standard. It should be noted that it should be understood that the term "state" and the term "mode" can be used interchangeably without changing the meaning of the underlying operation of the device.

[0004] Generally, when a device is used to operate in a low power mode, operation of the device in a radio frequency (RF) analog domain is preferred. It is well known that the power consumption of a digital processing circuit is relatively high, especially when the digital processing circuit operates at a relatively high frequency. An analog-to-digital converter (ADC) is one of the known digital processing circuits that implements digital processing, and it is well known that it causes power consumption. Summary of the invention

[0005] Some embodiments of the present invention relate to the use of a linear frequency modulation signal in a synchronization process. For synchronization purposes, a UE may receive and process the linear frequency modulation signal in a low power mode. The use of the linear frequency modulation signal may enable low-complexity processing in the RF analog domain. As is well known, processing in the RF analog domain may reduce power consumption relative to processing in the baseband digital domain. These advantages may be achieved by sending a linear frequency modulation signal from a device close to the UE. The near-end device has a minimum flight time, so that the synchronization offset may be estimated relatively accurately. Using a near-end device to send a linear frequency modulation signal may also reuse time-frequency resources for synchronization within a given network. The reduction in beam scanning at the UE may also be shown to reduce power consumption at the UE and reduce processing complexity. After the UE interacts with the device that sends the synchronization signal, the device that sends the synchronization signal may report measurements to the network. Thus, the network may be enabled to estimate the timing advance of the UE.

[0006] As is known, conventional synchronization techniques involve beam scanning and baseband digital processing, which are both power-consuming.

[0007] Various aspects of the present application are characterized by relatively low power consumption. The relatively low power consumption is achieved by performing most of the processing in the RF analog domain and relaxing the need for beam scanning by using proximity. Conveniently, various aspects of the present application can be shown as achieving relatively low complexity and relatively high accuracy for the estimation of synchronization offset estimation. In addition, various aspects of the present application can be shown as providing the possibility of UE multiplexing with relatively low time-frequency resource overhead.

[0008] According to one aspect of the present invention, a method for performing on a first device is provided. The method includes: receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration including configuration information of a first linear frequency modulation signal. The method also includes: when the first device is in a low power operation mode, receiving the first linear frequency modulation signal from a second device; measuring the first linear frequency modulation signal to obtain an estimated synchronization offset between a first clock at the first device and a second clock at the second device; and modifying the first clock based on the estimated synchronization offset.

[0009] According to one aspect of the present invention, a first device is provided. The first device includes a first clock and a receiver, the receiver is used to receive a linear frequency modulation signal configuration, the linear frequency modulation signal configuration includes configuration information of a first linear frequency modulation signal, and receives the first linear frequency modulation signal from a second device. The first device also includes: a memory storing instructions; a processor, which performs the following operations by executing the instructions when the first device is in a low-power operation mode: measuring the first linear frequency modulation signal to obtain an estimated synchronization offset between the first clock and a second clock at the second device; modifying the first clock based on the estimated synchronization offset.

[0010] According to one aspect of the present invention, a method for performing on a first device is provided. The method includes: receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration including configuration information of a first linear frequency modulation signal. The method also includes: when a second device is in a low power operation mode, according to the configuration information of the first linear frequency modulation signal, sending the first linear frequency modulation signal to the second device; receiving a second linear frequency modulation signal from the second device; obtaining a measurement of the second linear frequency modulation signal to determine that the second linear frequency modulation signal is for the first device; and sending a measurement report to a third device based on the measurement of the second linear frequency modulation signal.

[0011] According to one aspect of the present invention, a first device is provided. The first device includes: a receiver for receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration including configuration information of a first linear frequency modulation signal, and receiving a second linear frequency modulation signal from a second device. The first device also includes: a transmitter for sending the first linear frequency modulation signal to the second device according to the configuration information of the first linear frequency modulation signal when the second device is in a low-power operation mode; a memory for storing instructions; a processor for performing the following operations by executing the instructions when the second device is in a low-power operation mode: obtaining a measurement of the second linear frequency modulation signal to determine that the second linear frequency modulation signal is for the first device; and sending a measurement report to a third device using the transmitter based on the measurement of the second linear frequency modulation signal.

[0012] According to one aspect of the present invention, a method is provided. The method comprises: before the second device enters a low power mode, sending configuration details of a first linear frequency modulation signal to the second device at a first device; sending configuration details of a second linear frequency modulation signal to a third device; receiving a report from the third device including measurements of the first linear frequency modulation signal made at the third device; and processing the measurements.

[0013] According to one aspect of the present invention, a first device is provided. The first device comprises: a transmitter for sending configuration details of a first linear frequency modulation signal to the second device before the second device enters a low power mode; and sending configuration details of a second linear frequency modulation signal to a third device. The first device also comprises: a receiver for receiving a report including measurements of the first linear frequency modulation signal at the third device from the third device; a memory for storing instructions; and a processor for processing the measurements by executing the instructions.

[0014] According to one aspect of the present invention, a system is provided comprising a first device and a second device. The first device is used to send a first linear frequency modulation signal. The second device is used to receive the first linear frequency modulation signal and obtain an estimated synchronization offset between a first clock at the first device and a second clock at the second device. The second device is also used to send a second linear frequency modulation signal to the first device to indicate an association between the first device and the second device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more fully understand the embodiments of the present invention and its advantages, the following description is made by way of example with reference to the accompanying drawings, in which:

[0016] Figure 1 In the schematic diagram, a communication system in which an embodiment of the present invention may occur is shown, the communication system including a plurality of exemplary electronic devices and a plurality of exemplary transmission reception points and various networks;

[0017] Figure 2 The block diagram shows Figure 1 A communication system comprising a plurality of exemplary electronic devices, exemplary terrestrial transmission and reception points, exemplary non-terrestrial transmission and reception points, and various networks;

[0018] Figure 3 As a block diagram, various aspects of the present application are provided. Figure 2 Elements of an exemplary electronic device of Figure 2 Elements of an exemplary ground transmission receiving point and Figure 2 Elements of an exemplary non-terrestrial transmission reception point;

[0019] Figure 4 As a block diagram, various modules provided by various aspects of the present application that may be included in an exemplary electronic device, an exemplary terrestrial transmission reception point, and an exemplary non-terrestrial transmission reception point are shown;

[0020] Figure 5 As a block diagram, the perception management functions provided by various aspects of the present application are shown;

[0021] FIG6 shows a known structure of a synchronization signal (SS) block having four orthogonal frequency division multiplexing (OFDM) symbols;

[0022] FIG. 7 shows a known way to facilitate synchronization by sending SS blocks in different directions at different times using different beams;

[0023] FIG8 shows the known structure of a sidelink SS block for normal cyclic prefix OFDM;

[0024] Fig. 9 An exemplary network including a plurality of user equipments (UEs) associated with a transmission receiving point (TRP) provided by various aspects of the present application is shown, wherein the plurality of UEs include a leader UE and a target UE;

[0025] Fig.10 It shows that various aspects of this application provide Fig. 9 Access chirp signaling by a target UE in the illustrated exemplary network;

[0026] Fig.11 Exemplary steps of the method to be performed by the target UE provided in various aspects of the present application are shown;

[0027] Fig.12 Exemplary steps of the method to be performed by the leader UE provided in various aspects of the present application are shown;

[0028] Fig.13 Exemplary steps of the method to be performed by the TRP provided in various aspects of the present application are shown;

[0029] Fig.14 The manner in which four synchronous chirp signal configuration parameters affect the synchronous chirp signal is shown in a frequency-time graph;

[0030] Fig.15 The manner in which more than two synchronous chirp configuration parameters affect multiple synchronous chirp signals is shown in a frequency-time graph;

[0031] Fig.16 A first situation provided by various aspects of the present application is shown, wherein the starting frequency is used to distinguish a first synchronized linear frequency modulation signal sent by a first leader UE from a second synchronized linear frequency modulation signal sent by a second leader UE;

[0032] Fig.17A second situation provided by various aspects of the present application is shown, wherein the start time is used to distinguish a first synchronized linear frequency modulation signal sent by a first leader UE from a second synchronized linear frequency modulation signal sent by a second leader UE; both the start frequency and the start time are used.

[0033] Fig.18 A third situation provided by various aspects of the present application is shown, wherein both the starting frequency and the starting time are used to distinguish between a first synchronized linear frequency modulation signal sent by a first leader UE and a second synchronized linear frequency modulation signal sent by a second leader UE;

[0034] Fig.19 An example is shown in which there are two leader UEs near a target UE in low power mode;

[0035] Fig. 20 The basic structures of two leader UEs and a target UE provided by various aspects of the present application and representation of a synchronous linear frequency modulation signal are shown, wherein the basic structure of the target UE includes a matched filter and a peak detector;

[0036] Fig.21 It shows that various aspects of this application provide Fig. 20 An exemplary envelope of the output of the matched filter in;

[0037] Fig. 22 The steps in the exemplary method of processing a received synchronous linear frequency modulation signal provided by various aspects of the present application are shown;

[0038] Fig.23 Exemplary steps in the operation method of a given leader UE for accessing a linear frequency modulation signal provided by various aspects of the present application are shown;

[0039] Fig.24 The transmission of an access chirp signal having a specific chirp rate, a specific start frequency, and a specific start time provided by various aspects of the present application is shown;

[0040] Fig.25 It shows the TRP, the target UE and the leader UE associated with the target UE itself provided by various aspects of the present application;

[0041] Fig.26 The interaction between the leader UE, TRP and target UE provided by various aspects of the present application is shown in the signal flow diagram;

[0042] Fig. 27 A linear model of synchronization shift with two model parameters is shown. DETAILED DESCRIPTION

[0043] For illustrative purposes, specific exemplary embodiments will be explained in greater detail below with reference to the accompanying drawings.

[0044] The embodiments described herein represent information sufficient to practice the claimed subject matter and illustrate methods of practicing such subject matter. After reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the claimed subject matter and will recognize that the application of these concepts is not specifically addressed herein. It should be understood that these concepts and applications belong to the scope of the present invention and the appended claims.

[0045] In addition, it should be understood that any module, component or device for executing instructions disclosed herein may include or otherwise access one or more non-transitory computer / processor readable storage media for storing information, such as computer / processor readable instructions, data structures, program modules and / or other data. A non-exhaustive list of examples of non-transitory computer / processor readable storage media includes: magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices; compact disc read-only memory (CD-ROM), digital video disc or digital versatile disc (i.e., DVD), Blu-ray disc, etc. TM CDs, or other optical storage; volatile and non-volatile, removable and non-removable media, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other storage technology implemented in any method or technology. Any of these non-transitory computer / processor storage media can be part of a device or can be accessed or connected by a device. Computer / processor readable / executable instructions for implementing the applications or modules described herein can be stored or otherwise saved by such non-transitory computer / processor readable storage media.

[0046] refer to Figure 1, a simplified schematic diagram of a communication system is provided as an illustrative example but not limiting. The communication system 100 includes a radio access network 120. The radio access network 120 may be a next generation (e.g., sixth generation (6G) or higher) radio access network, or a traditional (e.g., 5G, 4G, 3G, or 2G) radio access network. One or more communication electrical devices (EDs) 110a, 110b, 110c, 110d, 110e, 110f, 110g, 110h, 110i, 110j (generally referred to as 110) may be interconnected with each other or connected to one or more network nodes (170a, 170b, generally referred to as 170) in the radio access network 120. The core network 130 may be part of the communication system and may be dependent on or independent of the radio access technology used in the communication system 100. In addition, the communication system 100 includes a public switched telephone network (PSTN) 140, the Internet 150, and other networks 160.

[0047] Figure 2 An exemplary communication system 100 is shown. Typically, the communication system 100 enables multiple wireless or wired elements to transmit data and other content. The purpose of the communication system 100 may be to provide content such as voice, data, video and / or text through broadcast, multicast and unicast, etc. The communication system 100 may operate by sharing resources (e.g., carrier spectrum bandwidth) between its constituent elements. The communication system 100 may include a terrestrial communication system and / or a non-terrestrial communication system. The communication system 100 may provide a wide range of communication services and applications (e.g., earth monitoring, remote sensing, passive sensing and positioning, navigation and tracking, autonomous distribution and mobility, etc.). The communication system 100 may provide a high degree of availability and robustness through the joint operation of a terrestrial communication system and a non-terrestrial communication system. For example, integrating a non-terrestrial communication system (or its components) into a terrestrial communication system may realize a heterogeneous network including multiple layers. Compared with traditional communication networks, heterogeneous networks may obtain better overall performance through efficient multi-link joint operation, more flexible function sharing, and faster physical layer link switching between terrestrial networks and non-terrestrial networks.

[0048] The terrestrial communication system and the non-terrestrial communication system can be regarded as subsystems of the communication system. Figure 2In the example shown in FIG. 1 , the communication system 100 includes electronic devices (EDs) 110a, 110b, 110c, 110d (generally referred to as ED 110), radio access networks (RANs) 120a and 120b, non-terrestrial communication networks 120c, core networks 130, public switched telephone networks (PSTNs) 140, the Internet 150, and other networks 160. The RANs 120a and 120b include corresponding base stations (BSs) 170a and 170b, which may be generally referred to as terrestrial transmit and receive points (T-TRPs) 170a and 170b. The non-terrestrial communication network 120c includes an access node 172, which may be generally referred to as a non-terrestrial transmit and receive point (NT-TRP) 172.

[0049] Any ED 110 may alternatively or additionally be used to connect, access, or communicate with any T-TRP 170a and 170b, NT-TRP 172, Internet 150, core network 130, PSTN 140, other network 160, or any combination thereof. In some examples, ED 110a may perform uplink and / or downlink transmissions with T-TRP 170a via ground air interface 190a. In some examples, ED 110a, 110b, 110c, and 110d may also communicate directly with each other via one or more sidelink air interfaces 190b. In some examples, ED 110d may perform uplink and / or downlink transmissions with NT-TRP 172 via non-ground air interface 190c.

[0050] The air interfaces 190a and 190b may use similar communication technologies, such as any suitable wireless access technology. For example, the communication system 100 may implement one or more channel access methods in the air interfaces 190a and 190b, such as code division multiple access (CDMA), space division multiple access (SDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA) or direct Fourier transform spread OFDMA (DFT-OFDMA). The air interfaces 190a and 190b may utilize other high-dimensional signal spaces, which may involve a combination of orthogonal dimensions and / or non-orthogonal dimensions.

[0051] The non-terrestrial air interface 190c may enable communication between ED 110d and one or more NT-TRPs 172 via a wireless link or a simple link. For some examples, the link is a dedicated connection for unicast transmission, a connection for broadcast transmission, or a connection between a group of EDs 110 and one or more NT-TRPs 175 for multicast transmission.

[0052] The RANs 120a and 120b communicate with the core network 130 to provide various services, such as voice, data, and other services, to the EDs 110a, 110b, and 110c. The RANs 120a and 120b and / or the core network 130 may communicate directly or indirectly with one or more other RANs (not shown), which may or may not be directly served by the core network 130 and may or may not use the same radio access technology as the RANs 120a and / or RANs 120b. The core network 130 may also serve as a gateway access between (i) the RANs 120a and 120b and / or the EDs 110a, 110b, 110c, and (ii) other networks (e.g., the PSTN 140, the Internet 150, and other networks 160). In addition, some or all of the EDs 110a, 110b, 110c may include functionality to communicate with different wireless networks over different radio links using different radio technologies and / or protocols. Instead of (or in addition to) wireless communication, EDs 110a, 110b, 110c may also communicate with a service provider or switch (not shown) and with the Internet 150 through a wired communication channel. PSTN 140 may include a circuit-switched telephone network for providing plain old telephone service (POTS). Internet 150 may include computer networks and / or subnets (intranets) and include protocols such as Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), etc. EDs 110a, 110b, and 110c may be multi-mode devices capable of operating according to a variety of wireless access technologies and include a plurality of transceivers required to support these wireless access technologies.

[0053] Figure 3Another example of ED 110 and base stations 170a, 170b and / or 170c is shown. ED 110 is used to connect people, objects, machines, etc. ED 110 can be widely used in various scenarios, such as cellular communication, device-to-device (D2D), vehicle to everything (V2X), peer-to-peer (P2P), machine-to-machine (M2M), machine-type communication (MTC), Internet of Things (IOT), virtual reality (VR), augmented reality (AR), mixed reality (MR), virtual reality, digital twin, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable devices, smart transportation, smart city, drones, robots, remote sensing, passive sensing, positioning, navigation and tracking, autonomous delivery and mobility, etc.

[0054] Each ED 110 represents any suitable end-user device for wireless operation, and may include devices such as (or may be referred to as) user equipment (UE), wireless transmit / receive unit (WTRU), mobile station, fixed or mobile user unit, cellular phone, station (STA), machine type communication (MTC) device, personal digital assistant (PDA), smart phone, laptop, computer, tablet, wireless sensor, consumer electronic device, wearable device (such as watch, head mounted device, glasses), smart book, vehicle, car, truck, bus, train or IoT device, industrial equipment or devices in the above devices (such as communication module, modem, or chip), etc. The next generation ED 110 may be referred to using other terms. Each base station 170a and 170b is a T-TRP and will be referred to as T-TRP 170 hereinafter. Similarly, in Figure 3 , the NT-TRP will be referred to hereinafter as NT-TRP 172. Each ED 110 connected to T-TRP 170 and / or NT-TRP 172 may be dynamically or semi-statically opened (i.e., established, activated, or enabled), closed (i.e., released, deactivated, or disabled), and / or configured in response to one or more of connection availability and connection necessity.

[0055] ED 110 includes a transmitter 201 and a receiver 203 coupled to one or more antennas 204. Only one antenna 204 is shown. One, some or all of the antennas 204 may also be panels. Transmitter 201 and receiver 203 may be integrated into, for example, a transceiver. The transceiver is used to modulate data or other content for transmission by at least one antenna 204 or a network interface controller (NIC). The transceiver may also be used to demodulate data or other content received by at least one antenna 204. Each transceiver includes any suitable structure for generating signals for wireless or wired transmission and / or for processing signals received by wireless or wired means. Each antenna 204 includes any suitable structure for sending and / or receiving wireless signals or wired signals.

[0056] ED 110 includes at least one memory 208. Memory 208 stores instructions and data used, generated, or collected by ED 110. For example, memory 208 can store software instructions or modules that are used to implement some or all of the functions and / or embodiments described herein and are executed by one or more processing units (e.g., processor 210). Each memory 208 includes any suitable one or more volatile and / or non-volatile storage and retrieval devices. Any suitable type of memory can be used, such as random access memory (RAM), read-only memory (ROM), hard disk, optical disk, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, processor cache, etc.

[0057] ED 110 may also include one or more input / output devices (not shown) or interfaces (e.g., connected to Figure 1 The input / output device can interact with users or other devices in the network. Each input / output device includes any suitable structure for providing information to a user or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display or touch screen, including network interface communication, for example, through operation.

[0058] ED 110 includes a processor 210 for performing operations, including operations related to preparing transmissions for uplink transmission to NT-TRP 172 and / or T-TRP 170, processing downlink transmissions received from NT-TRP 172 and / or T-TRP 170, and processing sidelink transmissions with another ED 110. Processing operations related to preparing transmissions for uplink transmission may include operations such as encoding, modulation, transmit beamforming, and generating symbols for transmission. Processing operations related to processing downlink transmissions may include operations such as receive beamforming, demodulation, and decoding received symbols. According to an embodiment, the downlink transmission may be received by receiver 203, possibly using receive beamforming, and processor 210 may extract signaling from the downlink transmission (e.g., by detecting and / or decoding the signaling). An example of signaling may be a reference signal sent by NT-TRP 172 and / or T-TRP 170. In some embodiments, the processor 210 implements transmit beamforming and / or receive beamforming based on an indication of a beam direction, such as beam angle information (BAI), received from the T-TRP 170. In some embodiments, the processor 210 may perform operations related to network access (e.g., initial access) and / or downlink synchronization, such as operations related to detecting a synchronization sequence, decoding, and obtaining system information. In some embodiments, the processor 210 may perform channel estimation, for example, using a reference signal received from the NT-TRP 172 and / or the T-TRP 170.

[0059] Although not shown, the processor 210 may form part of the transmitter 201 and / or the receiver 203. Although not shown, the memory 208 may form part of the processor 210.

[0060] The processor 210 and the processing components of the transmitter 201 and the processing components of the receiver 203 may each be implemented by the same or different one or more processors, which are used to execute instructions stored in a memory (e.g., in the memory 208). Alternatively, the processor 210 and some or all of the processing components of the transmitter 201 and the processing components of the receiver 203 may each be implemented using a dedicated circuit, such as a programmed field-programmable gate array (FPGA), a central processing unit (CPU), a graphical processing unit (GPU), or an application-specific integrated circuit (ASIC).

[0061] In some implementations, T-TRP 170 may use other names, such as base station, base transceiver station (BTS), wireless base station, network node, network device, network side device, sending / receiving node, Node B, evolved NodeB (eNodeB or eNB), home eNodeB, next generation NodeB (gNB), transmission point (TP), site controller, access point (AP), wireless router, relay station, remote radio head, ground node, ground network device, ground base station, base band unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), centralized unit (CU), distributed unit (DU), positioning node, etc. T-TRP 170 may be a macro BS, a micro BS, a relay node, a host node, etc., or a combination thereof. T-TRP 170 may refer to the above-mentioned device or to a means in the above-mentioned device (eg, a communication module, a modem or a chip).

[0062] In some embodiments, various parts of the T-TRP 170 may be distributed. For example, some modules of the T-TRP 170 may be located away from the device housing the antenna 256 of the T-TRP 170, and may be coupled to the device housing the antenna 256 via a communication link (not shown) (sometimes referred to as a fronthaul, such as a common public radio interface (CPRI)). Therefore, in some embodiments, the term T-TRP 170 may also refer to modules on the network side that perform processing operations such as ED110 location determination, resource allocation (scheduling), message generation, and encoding / decoding, which are not necessarily part of the device housing the antenna 256 of the T-TRP 170. These modules may also be coupled to other T-TRPs. In some embodiments, the T-TRP 170 may actually be multiple T-TRPs that operate together to serve the ED 110, for example, by using coordinated multi-point transmission.

[0063] like Figure 3As shown, the T-TRP 170 includes at least one transmitter 252 and at least one receiver 254 coupled to one or more antennas 256. Only one antenna 256 is shown. One, some or all of the antennas 256 may also be panels. The transmitter 252 and the receiver 254 may be integrated into a transceiver. The T-TRP 170 also includes a processor 260 for performing operations, including operations related to preparing transmissions for downlink transmission to the ED 110, processing uplink transmissions received from the ED 110, preparing transmissions for backhaul transmission to the NT-TRP 172, and processing transmissions received from the NT-TRP 172 via the backhaul. Processing operations related to preparing for downlink transmission or backhaul transmission may include operations such as encoding, modulation, precoding (e.g., multiple input multiple output (MIMO) precoding), transmit beamforming, and generating symbols for transmission. Processing operations related to processing transmissions received in uplink transmissions or via backhaul transmissions may include operations such as receive beamforming, demodulation, and decoding received symbols. The processor 260 may also perform operations related to network access (e.g., initial access) and / or downlink synchronization, such as generating the content of a synchronization signal block (SSB), generating system information, etc. In some embodiments, the processor 260 also generates an indication of a beam direction (e.g., a BAI), which may be scheduled by the scheduler 253 for transmission. The processor 260 performs other network-side processing operations described herein, such as determining the location of the ED 110, determining the location of the deployed NT-TRP 172, etc. In some embodiments, the processor 260 may generate signaling, such as configuring one or more parameters of the ED 110 and / or one or more parameters of the NT-TRP 172. Any signaling generated by the processor 260 is sent by the transmitter 252. It should be noted that the "signaling" used herein may also be referred to as control signaling. Dynamic signaling may be transmitted in a control channel (eg, a physical downlink control channel (PDCCH)), and static or semi-static higher-layer signaling may be included in a packet transmitted in a data channel (eg, a physical downlink shared channel (PDSCH)).

[0064] The scheduler 253 may be coupled to the processor 260. The scheduler 253 may be included within the T-TRP 170 or operate separately from the T-TRP 170. The scheduler 253 may schedule uplink transmissions, downlink transmissions, and / or backhaul transmissions, including issuing scheduling grants and / or configuring scheduling-free (“configured grants”) resources. The T-TRP 170 also includes a memory 258 for storing information and data. The memory 258 stores instructions and data used, generated, or collected by the T-TRP 170. For example, the memory 258 may store software instructions or modules for implementing some or all of the functionality and / or embodiments described herein and executed by one or more processors 260.

[0065] Although not shown, the processor 260 may form a part of the transmitter 252 and / or the receiver 254. In addition, although not shown, the processor 260 may implement the scheduler 253. Although not shown, the memory 258 may form a part of the processor 260.

[0066] The processor 260, the scheduler 253, and the processing components of the transmitter 252 and the receiver 254 may each be implemented by the same or different one or more processors that execute instructions stored in a memory (e.g., the memory 258). Alternatively, some or all of the processor 260, the scheduler 253, and the processing components of the transmitter 252 and the processing components of the receiver 254 may be implemented using dedicated circuits (e.g., FPGA, CPU, GPU, or ASIC).

[0067] It should be noted that the NT-TRP 172 is shown as a drone only as an example, and the NT-TRP 172 can be implemented in any suitable non-ground form, such as a high-altitude platform, a satellite, a high-altitude platform as an international mobile communication base station, and an unmanned aerial vehicle, which will be discussed below. In addition, in some implementations, the NT-TRP 172 may use other names, such as a non-ground node, a non-ground network device, or a non-ground base station. The NT-TRP 172 includes a transmitter 272 and a receiver 274 coupled to one or more antennas 280. Only one antenna 280 is shown. One, part, or all of the antennas may also be a panel. The transmitter 272 and the receiver 274 may be integrated into a transceiver. NT-TRP 172 also includes a processor 276 for performing operations, including operations related to preparing transmissions for downlink transmission to ED 110, processing uplink transmissions received from ED 110, preparing transmissions for backhaul transmission to T-TRP 170, and processing transmissions received from T-TRP 170 via backhaul. Processing operations related to preparing for downlink transmission or backhaul transmission may include operations such as encoding, modulation, precoding (e.g., MIMO precoding), transmit beamforming, and generating symbols for transmission. Processing operations related to processing transmissions received in uplink transmission or via backhaul transmission may include operations such as receive beamforming, demodulating received signals, and decoding received symbols. In some embodiments, processor 276 implements transmit beamforming and / or receive beamforming based on beam direction information (e.g., BAI) received from T-TRP 170. In some embodiments, processor 276 may generate signaling, such as configuring one or more parameters of ED 110. In some embodiments, NT-TRP 172 implements physical layer processing but does not implement higher layer functions, such as functions of the medium access control (MAC) or radio link control (RLC) layers. Since this is only an example, more generally, NT-TRP 172 may implement higher layer functions in addition to physical layer processing.

[0068] The NT-TRP 172 also includes a memory 278 for storing information and data. Although not shown, the processor 276 may form part of the transmitter 272 and / or the receiver 274. Although not shown, the memory 278 may form part of the processor 276.

[0069] Processor 276 and the processing components of transmitter 272 and receiver 274 may each be implemented by the same or different one or more processors that execute instructions stored in memory (e.g., memory 278). Alternatively, processor 276 and some or all of the processing components of transmitter 272 and receiver 274 may be implemented using dedicated circuits (e.g., FPGA, CPU, GPU, or ASIC). In some embodiments, NT-TRP 172 may actually be multiple NT-TRPs that operate together to serve ED 110, such as through coordinated multi-point transmission.

[0070] The T-TRP 170, NT-TRP 172, and / or ED 110 may include other components, but these components are omitted for clarity.

[0071] according to Figure 4 One or more steps of the methods of each embodiment provided herein may be executed by a corresponding unit or module. Figure 4 Units or modules in a device are shown, such as in ED 110, in T-TRP 170, or in NT-TRP 172. For example, a signal can be sent by a sending unit or a sending module. A signal can be received by a receiving unit or a receiving module. A signal can be processed by a processing unit or a processing module. Other steps can be performed by an artificial intelligence (AI) or machine learning (ML) module. The corresponding units or modules can be implemented using hardware, one or more components or devices that execute software, or a combination thereof. For example, one or more of the units or modules can be integrated circuits, such as programmed FPGAs, CPUs, GPUs, or ASICs. It should be understood that if the above modules are implemented using software for execution by a processor or the like, these modules can be retrieved by the processor in whole or in part as needed, retrieved individually or collectively for processing, retrieved in one or more instances as needed, and these modules themselves can include instructions for further deployment and instantiation.

[0072] Other details about ED 110, T-TRP 170 and NT-TRP 172 are known to those skilled in the art. Therefore, these details are omitted here.

[0073] UE location information is commonly used in cellular communication networks to improve various performance indicators of the network. For example, such performance indicators may include capacity, agility, and efficiency. Improvements can be achieved when elements of the network utilize the UE's location, behavior, mobility patterns, etc. in the context of a priori information describing the wireless environment in which the UE operates.

[0074] The perception system can be used to help collect UE pose information, including the position of the UE in the global coordinate system, the speed and direction of movement of the UE in the global coordinate system, directional information, and information about the wireless environment. "Position" is also called "orientation", and these two terms can be used interchangeably in this article. Examples of well-known perception systems include radio detection and ranging (RADAR) and light detection and ranging (LIDAR). Although perception systems are usually separated from communication systems, it may be advantageous to collect information using an integrated system, which reduces the hardware (and cost) in the system and the time, frequency or space resources required to perform these two functions. However, using communication system hardware to perform perception of UE pose and environmental information is a very challenging problem to be solved. The difficulty of this problem is related to factors such as the limited resolution of the communication system, the dynamics of the environment, and the large number of objects whose electromagnetic properties and orientation need to be estimated.

[0075] Therefore, synaesthesia (also called telepathy) is a desirable feature in existing and future communication systems.

[0076] Any or all of ED 110 and BS 170 may be sensing nodes in system 100. A sensing node is a network entity that performs sensing by sending and receiving sensing signals. Some sensing nodes are communication devices that perform both communication and sensing. However, some sensing nodes may not perform communication but are dedicated to sensing. Sensing agent 174 is an example of a sensing node dedicated to sensing. Unlike ED 110 and BS 170, sensing agent 174 does not send or receive communication signals. However, sensing agent 174 can transmit configuration information, sensing information, signaling information, or other information within communication system 100. Sensing agent 174 can communicate with core network 130 to communicate information with the rest of the devices in communication system 100. For example, sensing agent 174 can determine the location of ED 110a and send the information to base station 170a through core network 130. Although Figure 2 Only one awareness proxy 174 is shown, but any number of awareness proxies may be implemented in the communication system 100. In some embodiments, one or more awareness proxies may be implemented at one or more RANs 120.

[0077] The sensing node can combine the sensing-based technology with the reference signal-based technology to enhance the UE posture determination. This type of sensing node may also be referred to as a sensing management function (SMF). In some networks, SMF may also be referred to as a location management function (LMF). SMF may be implemented as a physically independent entity, located at the core network 130, and connected to multiple BS170. In other aspects of the present application, SMF may be implemented as a logical entity co-located inside the BS170 by the logic executed by the processor 260.

[0078] like Figure 5 As shown, SMF 176 includes at least one processor 290, at least one transmitter 282, at least one receiver 284, one or more antennas 286 and at least one memory 288 when implemented as physically independent entities. Transceivers not shown can be used instead of transmitter 282 and receiver 284. Scheduler 283 can be coupled to processor 290. Scheduler 283 can be included in SMF 176 or operate separately from SMF 176. Processor 290 implements various processing operations of SMF 176, such as signal decoding, data processing, power control, input / output processing or any other function. Processor 290 can also be used to implement some or all of the functions and / or embodiments described in more detail above. Each processor 290 includes any suitable processing or computing device for performing one or more operations. For example, each processor 290 can include a microprocessor, a microcontroller, a digital signal processor, a field programmable gate array or an application-specific integrated circuit.

[0079] Reference signal based pose determination techniques belong to the "active" pose estimation paradigm. In the active pose estimation paradigm, an interrogator of pose information (e.g., UE 110) participates in the process of determining the interrogator's pose. The interrogator may send or receive (or send and receive) signals specific to the pose determination process. Positioning techniques based on global navigation satellite systems (GNSS) such as the known global positioning system (GPS) are other examples of the active pose estimation paradigm.

[0080] In contrast, perception techniques such as radar-based ones can be considered to belong to the “passive” pose determination paradigm, in which the target is oblivious to the pose determination process.

[0081] By integrating perception and communication in one system, the system does not need to operate according to only a single paradigm. Therefore, the combination of perception-based techniques and reference signal-based techniques can produce enhanced pose determination.

[0082] Enhanced pose determination may, for example, include obtaining UE channel subspace information, which is particularly useful for UE channel reconstruction at the sensing node, especially for beam-based operations and communications. The UE channel subspace is a subset of the entire algebraic space defined in the spatial domain, in which the entire channel from TP to UE is located. Therefore, the UE channel subspace defines the TP to UE channel with very high accuracy. The impact of signals sent on other subspaces on the UE channel is negligible. Understanding the UE channel subspace helps reduce the work required for channel measurements at the UE and channel reconstruction at the network side. Therefore, compared with traditional methods, the combination of sensing-based techniques and reference signal-based techniques can achieve UE channel reconstruction with less overhead. Subspace information can also facilitate subspace-based sensing to reduce sensing complexity and improve sensing accuracy.

[0083] In some embodiments of synaesthesia, the same radio access technology (RAT) is used for both sensing and communication. This avoids the need to reuse two different RATs on one carrier spectrum, or to use two different carrier spectrums for the two different RATs.

[0084] In an embodiment where one RAT is used to integrate sensing and communication, the first set of channels may be used to send sensing signals and the second set of channels may be used to send communication signals. In some embodiments, each channel in the first set of channels and each channel in the second set of channels is a logical channel, a transport channel, or a physical channel.

[0085] At the physical layer, communication and perception can be performed through separate physical channels. For example, a first physical downlink shared channel (PDSCH-C) is defined for data communication, while a second physical downlink shared channel (PDSCH-S) is defined for perception. Similarly, separate physical uplink shared channels (PUSCH), PUSCH-C and PUSCH-S, can be defined for uplink communication and perception.

[0086] In another example, the same PDSCH and PUSCH may also be used for communication and perception, where separate logical layer channels and / or transport layer channels are defined for communication and perception. It should also be noted that one or more control channels and one or more data channels used for perception may have the same or different channel structures (formats) and occupy the same or different frequency bands or bandwidth portions.

[0087] In another example, a common physical downlink control channel (PDCCH) and a common physical uplink control channel (PUCCH) can be used to carry control information for sensing and communication. Alternatively, a separate physical layer control channel can be used to carry separate control information for communication and sensing. For example, PUCCH-S and PUCCH-C can be used for uplink control for sensing and communication, respectively, and PDCCH-S and PDCCH-C can be used for downlink control for sensing and communication, respectively.

[0088] At each of the physical, transport, and logical layers, different combinations of shared and dedicated channels for sensing and communication may be used.

[0089] The word "RADAR" is derived from the phrase "Radio Detection and Ranging"; however, expressions with different capitalization forms (for example, "Radar" and "radar") are equally valid and are now more common. Radar is generally used to detect the presence and location of objects. A radar system radiates radio frequency energy and receives echoes of energy reflected from one or more targets. The system determines the pose of a given target based on the echoes returned from the given target. The radiated energy can be in the form of energy pulses or continuous waves, which can be represented or defined by a specific waveform. Examples of waveforms used in radar include frequency modulated continuous wave (FMCW) and ultra-wideband (UWB) waveforms.

[0090] Radar systems can be monostatic, bistatic, or multistatic. In a monostatic radar system, the radar signal transmitter and receiver are co-located, for example integrated into the transceiver. In a bistatic radar system, the transmitter and receiver are spatially separated by a distance comparable to or greater than the expected target distance (often called range). In a multistatic radar system, two or more radar components are spatially distinct but have a shared coverage area. Multistatic radars are also called multisite or mesh radars.

[0091] Ground-based radar applications face challenges such as multipath propagation and shadowing impairments. Another challenge is the identifiability issue, as ground targets have similar physical properties. Integrating sensing into communications systems is likely to face these same challenges, and more.

[0092] Communication nodes can be half-duplex or full-duplex. Half-duplex nodes cannot use the same physical resources (time, frequency, etc.) to send and receive at the same time; in contrast, full-duplex nodes can use the same physical resources to send and receive. Existing commercial wireless communication networks are all half-duplex. Even if full-duplex communication networks become practical in the future, it is expected that at least some of the nodes in the network will still be half-duplex nodes because half-duplex devices are less complex and have lower cost and power consumption. Specifically, full-duplex implementation is more challenging at higher frequencies (for example, in the millimeter wave band), which is very challenging for small, low-cost devices (such as femtocell base stations and UEs).

[0093] The limitations of half-duplex nodes in communication networks pose further challenges to devices and systems that integrate sensing and communication into communication networks. For example, both half-duplex and full-duplex nodes can perform dual-station sensing or multi-station sensing, but single-station sensing usually requires the sensing node to have full-duplex capabilities. Half-duplex nodes can perform single-station sensing with certain limitations, such as in pulse radars with specific duty cycles and ranging capabilities.

[0094] The characteristics of a perceptual signal or a signal used for both perceptual and communication include the waveform of the signal and the frame structure of the signal. The frame structure defines the time domain boundaries of the signal. The waveform describes the shape of the signal as a function of time and frequency. Examples of waveforms that can be used for perceptual signals include ultra-wideband (UWB) pulses, frequency modulated continuous wave (FMCW) or "linear frequency modulation", orthogonal frequency division multiplexing (OFDM), cyclic prefix (CP)-OFDM, and discrete Fourier transform spread (DFT-s)-OFDM.

[0095] In one embodiment, the sensing signal is a linear frequency modulation signal with a bandwidth of B and a duration of T. Such linear frequency modulation signals are generally known for their use in FMCW radar systems. The linear frequency modulation signal is composed of a pulse from an initial (starting) time t chirp0 The initial (starting) frequency f chirp0 To the final time t chirp1 The final frequency f chirp1 The relationship between frequency (f) and time (t) can be expressed as a linear relationship ff chirp0 =α(tt chirp0 ),in, It can be called the “linear FM signal slope” or “linear FM signal rate”. The bandwidth of the linear FM signal can be defined as B = f chirp1 -f chirp0 , the duration of the linear frequency modulation signal can be defined as T = t chirp1 -t chirp0This linear frequency modulation signal can be represented in baseband representation as

[0096] Precoding as used herein may refer to any one or more coding operations or modulations that convert an input signal into an output signal. Precoding may be performed in different domains and typically converts an input signal in a first domain into an output signal in a second domain. Precoding may include linear operations.

[0097] MIMO technology enables an antenna array consisting of multiple antennas to send and receive signals to meet the requirements of high transmission rates. ED 110 and T-TRP 170 and / or NT-TRP can use MIMO to communicate using wireless resource blocks. MIMO uses multiple antennas at the transmitter to send wireless resource blocks on parallel wireless signals. It can be seen that multiple antennas can be used at the receiver. MIMO can beamform parallel wireless signals for reliable multipath transmission of wireless resource blocks. MIMO can bind parallel wireless signals that transmit different data to increase the data rate of the wireless resource block.

[0098] In recent years, a MIMO (massive MIMO) wireless communication system in which a T-TRP 170 and / or NT-TRP 172 is equipped with a large number of antennas has received extensive attention from academia and industry. In a massive MIMO system, a T-TRP 170 and / or NT-TRP 172 is usually equipped with more than 10 antenna units (see Figure 3Antenna 256 and antenna 280 in the T-TRP 170 and / or NT-TRP 172). The T-TRP 170 and / or NT-TRP 172 are typically operable to serve dozens (e.g., 40) ED 110. The large number of antenna units of the T-TRP 170 and NT-TRP 172 can greatly improve the spatial freedom of wireless communication, greatly improve the transmission rate, spectrum efficiency, and power efficiency, and greatly reduce interference between cells. The increase in the number of antennas can enable each antenna unit to be made with a smaller size and lower cost. Using the spatial freedom provided by the large-scale antenna units, the T-TRP 170 and NT-TRP 172 of each cell can communicate with multiple EDs 110 in the cell simultaneously on the same time-frequency resources, thereby greatly improving the spectrum efficiency. The large number of antenna units of the T-TRP 170 and / or NT-TRP 172 also enables each user to have better spatial directivity for uplink and downlink transmissions, thereby reducing the transmit power of the T-TRP 170 and / or NT-TRP 172 and ED 110, and correspondingly improving the power efficiency. When the number of antennas of T-TRP 170 and / or NT-TRP 172 is large enough, the random channels between each ED 110 and T-TRP 170 and / or NT-TRP 172 can be nearly orthogonal, thereby reducing the interference between cells and users and the impact of noise. The above advantages make massive MIMO have broad application prospects.

[0099] A MIMO system may include a receiver connected to a receive (Rx) antenna, a transmitter connected to a transmit (Tx) antenna, and a signal processor connected to the transmitter and the receiver. Each of the Rx antenna and the Tx antenna may include multiple antennas. For example, the Rx antenna may have a uniform linear array (ULA) antenna, in which multiple antennas are arranged in rows at even intervals. When a radio frequency (RF) signal is transmitted through the Tx antenna, the Rx antenna may receive a reflected and returned signal from a forward target.

[0100] In some embodiments of a MIMO system, a non-exhaustive list of possible elements or possible configurable parameters includes: a panel; and a beam.

[0101] A panel is a unit of an antenna group or antenna array or antenna subarray that can independently control a Tx beam or an Rx beam.

[0102] The beam can be formed by amplitude and / or phase weighting of data sent or received by at least one antenna port. The beam can be formed by other methods such as adjusting relevant parameters of the antenna unit. The beam may include a Tx beam and / or an Rx beam. The transmit beam indicates the signal strength distribution formed in different directions of space after the signal is sent by the antenna. The receive beam indicates the signal strength distribution of the wireless signal received from the antenna in different directions of space. The beam information may include a beam identifier, an antenna port identifier, a channel state information reference signal (CSI-RS) resource identifier, an SSB resource identifier, a sounding reference signal (SRS) resource identifier, or other reference signal resource identifiers.

[0103] It is believed that in future wireless systems (6G and beyond), various low power mode processes will rely on "RF-dominated" processing. It has been discussed previously that for low power mode processes, digital processing should be avoided as much as possible. Therefore, it can be understood that RF-dominated processing can be expected to occur largely in the analog domain. However, it should also be clear that the expected processing may not occur entirely in the analog domain. In fact, some level of digital baseband processing may be considered necessary. Such digital baseband processing may be used to a limited extent. Therefore, the results of the digital processing can be understood to be of limited accuracy. For example, an ADC with a low (e.g., sub-Nyquist) sampling rate can be used to reduce power consumption relative to an ADC using a typical (e.g., Nyquist) or higher sampling rate.

[0104] Examples of low power mode procedures may include: low power sensing; low power positioning; low power paging; and communicating using backscatter.

[0105] It can be shown that synchronization between UE 110 and a network entity (eg, TRP 170) with which the UE is to communicate enables UE 110 to operate efficiently when UE 110 implements RF-dominant procedures.

[0106] Synchronization can be shown to enable UE 110 to avoid performance losses that can be shown to occur due to interference caused by synchronization offset. In addition, synchronization can also be shown to facilitate resource management. In addition, synchronization can be shown to reduce operational complexity. In fact, it is known that in those situations where synchronization is not available, complex operations can be used to overcome the problem of lack of synchronization.

[0107] When UE 110 or another node is operating in a low power mode, synchronization drift may increase due to the lack of communication activity. Therefore, it is important to devise methods to compensate for such drift. It should be noted that synchronization is important when UE 110 is in a connected state, in which UE 110 is communicating data with one or more network entities. It can be seen that it is useful for UE 110 to maintain synchronization in a low power mode when UE 110 is about to transition to a connected state. Conveniently, some parameters may be calculated as part of a synchronization process performed in one of the low power modes and do not need to be recalculated when UE 110 transitions to a connected state.

[0108] The 5G NR wireless standard addresses synchronization issues. On the one hand, synchronization of the access link between the UE 110 and the TRP 170 is addressed. On the other hand, synchronization of the sidelink connection between the first UE 110 and the second UE 110 is addressed. It can be shown that similar synchronization methods are used in both aspects (see A. Omri, M. Shaqfeh, A. Ali and H. Alnuweiri, "Synchronization Procedure in 5G NR Systems", IEEE Access, Vol. 7, March 2019, pp. 41286-41295).

[0109] For the first scenario, where UE 110 is to be synchronized with TRP 170, a known synchronization signal (SS) block is defined in the time-frequency domain.

[0110] FIG. 6 shows the structure of an SS block 600 having four OFDM symbols 602-0, 602-1, 602-2, 602-3.

[0111] The SS block 600 includes a primary synchronization signal (PSS) part 604 , a secondary synchronization signal (SSS) part 606 , and a plurality of physical broadcast channel (PBCH) parts 608 .

[0112] Occasionally, it may be expected that TRP 170 will broadcast SS block 600. UE 110 receiving SS block 600 may be shown to be able to estimate the synchronization offset between the clock at UE 110 and the clock at TRP 170.

[0113] UE 110 may responsively take steps to synchronize the clock at UE 110 with the clock at TRP 170 .

[0114] In the known 5G NR standard, the M sequence is used for the PSS part 604 of the SS block 600. In the known 5G NR standard, the gold sequence is used for the SSS part 606 of the SS block 600.

[0115] UE 110 may extract information such as cell ID, frame number, and resource allocation indication by measuring received SS block 600 and by decoding information within received SS block 600. It should be noted that, at UE 110, extracting the information involves processing received SS block 600 in the digital baseband domain.

[0116] At high frequencies, it is known that the TRP 170 may use directional transmissions with narrow beams. The use of narrow beams is a strategy for combating the relatively high propagation path losses associated with the use of high frequencies. That is, at high frequencies, the use of directional narrow beam transmissions may be shown to be important to the task of providing reasonable service coverage within a given network.

[0117] To facilitate synchronization, as shown in FIG7 , TRP 170 may transmit SS blocks at different times using different beams in different directions. Typically, SS blocks are organized into SS bursts. FIG7 shows a first SS burst 702-0 and a second SS burst 702-1. The start of the second SS burst 702-1 occurs after the start of the first SS burst 702-0 by a duration T. SS Duration T SS It may be referred to as an SS burst cycle. FIG7 shows that a first SS burst 702-0 includes L SS blocks (SSBs) 704-0, 704-1, 704-2, ..., 704-L-1 (collectively or individually 704). Each of the SSBs 704 is shown as being sent in a direction different from all remaining SSBs 704. The process of sending SSBs in different directions is generally referred to as "beam scanning".

[0118] Accordingly, UE 110 searches in different directions to attempt to receive and measure SSB 704. The process of attempting to receive SSB in different directions is also generally referred to as "beam scanning." It should be noted that, relative to attempting to receive and measure SSB in a known direction, the beam scanning process performed at UE 110 can be shown to involve increased resource overhead, increased complexity, and increased power consumption.

[0119] A similar approach is taken for sidelink synchronization. A "sidelink" is a link between two UEs that can be used for a variety of reasons, such as extending the coverage of the services provided by a particular TRP 170 to UEs that are not directly covered by the particular TRP 170. In such a scenario, a first UE (a "master" UE) within the coverage of a particular TRP 170 can act as a relay node to enable a second UE (a "slave" UE) that is not within the coverage of the particular TRP 170 to connect to the particular TRP 170. For sidelink synchronization, the master UE sends a sidelink synchronization signal (S-SS) block, receives the S-SS block from the slave UE and measures the synchronization offset. Figure 8 shows the structure of a sidelink SS block 800 for normal cyclic prefix (OFDM). The structure shown in Figure 8 has been adopted by the 3rd generation partnership project (3GPP) known as the 5G NR standard. The sidelink SS block 800 contains 14 OFDM symbols and includes an S-PSS part 804, an S-SSS part 806, multiple PSBCH parts 808 and a guard part 810.

[0120] In the known 5G NR standard, the M sequence is used for the S-PSS part 804 of the S-SS block 800. In the known 5G NR standard, the gold sequence is used for the S-SSS part 806 of the S-SS block 800.

[0121] It is contemplated that the received S-SS blocks may be processed in the digital baseband domain from the UE to extract the timing and information embedded in the S-SS blocks.

[0122] One major drawback of existing synchronization schemes is that they involve high power consumption. The relatively high power consumption can be attributed to the intensive digital processing in the baseband domain. The relatively high power consumption can also be attributed to the beam scanning to combat the high path loss at high frequencies. It should be noted that the main reason for the existing synchronization schemes that require digital baseband processing is the use of discrete sequences (such as M-sequences and golden sequences) as synchronization signals, and these sequences are embedded in OFDM symbols.

[0123] In summary, various aspects of the present application relate to distributed, back-and-forth, short-range linear frequency modulation signal transmission and measurement. In various aspects of the present application, a UE in a low power mode can be synchronized with a network entity with the help of one or more nearby UEs (or other nodes), which are in a connected state and are synchronized with the network entity because they are in a connected state. The nearby UE / node can be referred to as a "leader" UE / node. It should be noted that the name of the nearby UE / node can be "master UE / node", "primary UE / node" or "main UE / node" (these are just three alternative examples) instead of "leader UE / node".

[0124] In various aspects of the present application, multiple connected devices can be selected as leader UE / nodes, which can be UEs or other network nodes. For example, the selection can be performed at TRP 170 after receiving capability reports from multiple potential leader UE / nodes.

[0125] Before the target UE enters low power mode, the configuration of the "synchronous" linear frequency modulation signal (sent by the leader UE / node) and the configuration of the "access" linear frequency modulation signal (sent by the "target" UE in low power mode) can be sent to the leader UE / node and the target UE using control signaling. Subsequently, the leader UE sends the synchronous linear frequency modulation signal based on the relevant configuration. The UE in low power mode receives the synchronous linear frequency modulation signal and measures the synchronous linear frequency modulation signal to extract the timing of the received synchronous linear frequency modulation signal. The extraction of the timing of the received synchronous linear frequency modulation signal can be shown as enabling the target UE to obtain an estimate of the synchronization offset. After obtaining the estimate of the synchronization offset, the target UE can take steps to reduce the synchronization offset.

[0126] Fig. 9 A network including a plurality of UEs 110 associated with a TRP 170 is shown. The plurality of UEs 110 include a first leader UE 110L1, a second leader UE 110L2, and six target UEs 110T. The leader UEs 110L1, 110L2 are in connected mode. The target UEs 110T are in low power mode. The first leader UE 110L1 is associated with a first starting frequency f1 and a first coverage area 901. The second leader UE 110L2 is associated with a second starting frequency f2 and a second coverage area 902. Fig. 9 A line emanating from a first leader UE 110L1 and a line emanating from a second leader UE 110L2 are shown. These lines represent an exemplary transmission of synchronized chirp signals by the leader UEs 110L1, 110L2. Each line is associated with a chirp rate a0.

[0127] exist Fig. 9 In , α0, f1, and f2 are part of the synchronization signal configuration. Fig. 9 In the example shown, the synchronization signals transmitted by the two leader UEs 110L1, 110L2 are assigned a single chirp rate α0. In addition, the synchronization chirp signals are transmitted at the same initial (starting) time t chirp0 , but sent at different initial (starting) frequencies. Assume that the duration T of each synchronous linear frequency modulation signal is the same.

[0128] Fig.10 Shows Fig. 9 An access chirp signal transmission by a target UE 110T in an exemplary network is shown.

[0129] The target UE 110T sends an access chirp based on the previously defined configuration, which is received when the target UE 110T is in a connected state. The leader UEs 110L1, 110L2 receive the access chirp and measure it, thereby estimating different parameters. Fig.10 In the embodiment, the access chirp signals sent by different target UEs 110T are separated in the chirp rate domain. In addition, each target UE 110T can obtain the starting frequency of the access chirp signal sent by each target UE 110T from the measurement of the received synchronization signal. Fig.10 As shown, four of the target UEs 110T send access chirp signals to the first leader UE 110L1 at the first starting frequency f1 and at only one chirp rate among the four chirp rates α1, α2, α3, and α4. Fig.10 As shown, two of the target UEs 110T send access chirp signals to the second leader UE 110L2 at the second starting frequency f2 and the only chirp rate of the two chirp rates α5, α6. Finally, the leader UEs 110L1, 110L2 send the measurement results of the access chirp signals to the TRP 170 for further processing.

[0130] Conveniently, those aspects of the present application related to the linear frequency modulation signal exchange method for achieving synchronization can be shown as enabling RF-dominated processing, thereby reducing power consumption relative to the known baseband digital processing method for achieving synchronization discussed above. As previously mentioned, various aspects of the present application may involve some limited baseband processing after RF domain processing. Conveniently, it can be considered that the complexity of such baseband processing is much lower than the complexity of pure baseband operation. In addition, the linear frequency modulation signal exchange method for achieving synchronization can be shown as implementing a low-complexity version of synchronization offset estimation. For example, when the target UE 110T is in low power mode, pulse compression or matched filtering can be used to complete the synchronization offset estimation. In addition, each access linear frequency modulation signal is configured with a parameter called linear frequency modulation rate, which can be used to multiplex more UEs, which will be discussed later.

[0131] Conveniently, the chirp transmissions contemplated herein are short range and local. This is true for the synchronization chirp signals contemplated herein, as well as for the access chirp signals contemplated herein. The short range and local characteristics can be shown to provide several benefits.

[0132] One benefit of the short-range feature is that a parameter called "time of flight" (ToF) is relatively small. Typically, when a device (e.g., TRP 170 or UE 110) is used to estimate synchronization offset based on a single measurement, the ToF term behaves as an additive noise term. Therefore, the value of the estimated synchronization offset can be expressed as the sum of the actual synchronization offset and the ToF. However, it should be noted that since the ToF is small for the scenario envisioned herein, the dominant term in the estimated synchronization offset sum is the actual synchronization offset. Therefore, the estimated synchronization offset sum is approximately equal to the actual synchronization offset. It can be seen that by processing the measurement of the received synchronization signal, the device can obtain an estimated synchronization offset sum that provides an approximation of the actual synchronization offset with a reasonable level of accuracy. Conveniently, an approximation of the actual synchronization offset can be obtained without spending time and effort calculating the ToF.

[0133] For example, if the short distance over which the chirp signal is transmitted is 30 meters, the ToF can be calculated to be 0.1 microseconds. Therefore, any estimated synchronization offset and on the order of multiple microseconds can be understood to be within 0.1 microseconds of the actual synchronization offset.

[0134] Another benefit of the short range feature is that since path loss is not significant, omnidirectional transmission or wide beam transmission can be expected to be sufficient to transmit the chirp signal. Therefore, beam scanning is not required. By avoiding beam scanning associated with known synchronization schemes, the overhead, complexity and power consumption associated with beam scanning are also avoided.

[0135] Another benefit of the short-range feature is that time / frequency resources can be reused spatially. Therefore, the resource overhead associated with various aspects of the present application is relatively small.

[0136] Various aspects of the present application involve interactions between three types of devices.

[0137] One type of device is a target UE 110T (see Fig. 9 and Fig.10 ). The target UE 110T, which may also be referred to as a terminal device, is understood to be in a low power mode. The target UE 110T enters the low power mode to save energy. One object of various aspects of the present application is to synchronize the target UE 110T with the TRP 170 when the target UE 110T is in the low power mode. In various aspects of the present application, the target UE 110T is used to perform a method, and the exemplary steps of the method are as follows Fig.11 As shown. Initially, the target UE 110T may receive (step 1102) the configuration of the synchronous linear frequency modulation signal and the configuration of the access linear frequency modulation signal from the TRP 170 before entering the low power mode. After entering (step 1104) the low power mode, the target UE 110T may receive (step 1106) the synchronous linear frequency modulation signal from the leader UE 110L. The target UE 110T may also measure (step 1106) the received synchronous linear frequency modulation signal to obtain the measurement result. The target UE 110T may then obtain (step 1108) the estimated synchronization offset by processing the measurement result. Then, the target UE 110T may modify (step 1110) the clock at the target UE 110T based on the estimated synchronization offset. Optionally, the target UE 110T may infer (step 1112) the parameters to be used when sending the access linear frequency modulation signal from the measurement of the received synchronization signal. The target UE 110T may then send (step 1114) an access signal based on the configuration defined by the TRP 170. The access chirp signal sent in step 1114 may also be based on the parameters inferred in step 1112.

[0138] Another type of device is the leader UE 110L (see Fig. 9 and Fig.10 ). The leader UE 110L may be understood as a UE in a connected state. The leader UE 110L may also or additionally be understood as a node controlled by other networks, which is defined by several goals including facilitating synchronization of the target UE 110T. In various aspects of the present application, the leader UE 110L is used to perform a method, the exemplary steps of which are as follows: Fig.12. Initially, the leader UE 110L receives (step 1202) a configuration for a synchronization linear frequency modulation signal and a configuration for an access linear frequency modulation signal from TRP170. The specific leader UE 110L can send (step 1204) a synchronization linear frequency modulation signal based on the received configuration. Then, the specific leader UE 110L can receive (step 1206) an access linear frequency modulation signal from the target UE 110T. After receiving (step 1206) the access linear frequency modulation signal, the specific leader UE 110L can measure the timing and spatial direction of the received access linear frequency modulation signal. The specific leader UE 110L can determine (step 1208) which access linear frequency modulation signals (if any) are for the specific leader UE 110L based on the measurements obtained. For a specific access chirp that has been determined (step 1208) for a specific leader UE 110L, the specific leader UE 110L may send (step 1210) a measurement report to the TRP 170 that includes an indication of measurements associated with the specific access chirp.

[0139] Another type of device is the TRP 170 (see Figures 1 to 4 Figure 7 Fig. 9 and Fig.10 In various aspects of the present application, TRP 170 is used to perform a method, the exemplary steps of which are as follows: Fig.13 As shown in . Initially, TRP 170 can manage (step 1302) the configuration details of the access linear frequency modulation signal and the configuration details of the synchronous linear frequency modulation signal. Then, when the target UE 110T is in a connected state, TRP 170 can send (step 1304) the configuration details of the access linear frequency modulation signal and the configuration details of the synchronous linear frequency modulation signal to the target UE 110T. TRP 170 can also send (step 1306) the configuration details of the access linear frequency modulation signal and the configuration details of the synchronous linear frequency modulation signal to the leader UE 110L. It should be noted that steps 1304 and 1306 do not need to have a specific time order. After receiving (step 1308) the measurement report from the leader UE 110L, TRP 170 can process (step 1310) the measurements included in the measurement report to obtain the desired quantity.

[0140] Various aspects of the present application relate to the configuration of synchronous linear frequency modulation signals. Recall that the synchronous linear frequency modulation signal is sent by each leader UE 110L (step 1204, Fig.12 ). It can be managed for the i-th leader UE 110L (performed by TRP 170, see Fig.13Step 1302) Synchronize the specific configuration of the linear frequency modulation signal. The specific configuration of the synchronous linear frequency modulation signal can specify the following parameters: linear frequency modulation rate α i ; Start time t i Duration T i ; Starting frequency f i ; Transmit power P i ; The period of the synchronization signal in time and frequency is expressed. The period of the synchronization signal in time can be expressed by the time period The period of the synchronization signal in frequency can be expressed as the frequency period express.

[0141] Fig.14 Four synchronous linear frequency modulation signal configuration parameters (α i ,t i , T i and f i ) affects the way synchronous linear frequency modulation signals are used. Fig.14 The configuration parameters referenced in correspond to the configuration parameters used when the i-th leader UE 110L-i transmits (step 1306) the synchronous linear frequency modulation signal. It should be noted that the transmission range of the synchronous linear frequency modulation signal transmitted (step 1306) by the i-th leader UE 110L-i can be adjusted by the TRP 170, thereby adjusting the transmission power P i .

[0142] Fig.15 Two synchronous linear frequency modulation signal configuration parameters are shown in the frequency-time graph ( and ) affects the way multiple synchronous linear frequency modulation signals are affected.

[0143] The general steps in the synchronization process implemented in a network having a TRP 170, multiple leader UEs 110L and multiple target UEs 110T are as follows.

[0144] TRP 170 sends to leader UE 110L (step 1306, Fig.13 ) configuration details of the access linear frequency modulation signal and the configuration details of the corresponding synchronous linear frequency modulation signal. Before the target UE 110T enters the low power mode, the TRP 170 also sends (step 1304, Fig.13 ) The corresponding configuration details of the access linear frequency modulation signal and the configuration details of the synchronous linear frequency modulation signal. The configuration details are sent ( Fig.13 Steps 1304 and 1306) may be performed by TRP 170 using control signaling such as RRC configuration signaling.

[0145] Each leader UE 110L receives (step 1202, Fig.12 ) configuration details are sent to the target UE 110T (step 1204, Fig.12 ) synchronous linear frequency modulation signal.

[0146] At the representative target UE 110T, a signal is received from a nearby leader UE 110L (step 1106, Fig.11 ) synchronized linear frequency modulation signal. The representative target UE 110T uses RF-dominated processing to measure (step 1106, Fig.11 ), thereby obtaining (step 1108, Fig.11 The representative target UE 110T selects one of the leader UEs 110L based on the measurement and estimates (step 1108, Fig.11 ) relative to the selected leader UE 110L. The representative target UE 110T may modify the synchronization offset based on the estimated synchronization offset (step 1110, Fig.11 ) A clock at the representative target UE 110T. The representative target UE 110T may infer from measurements of received synchronization signals (step 1112, Fig.11 ) Parameters to use when sending access chirp signals.

[0147] Multiple leader UEs 110L may not be synchronized with each other. TRP 170 may have a management (step 1302, Fig.13 ) synchronized linear frequency modulation signal configuration to compensate for any synchronization offsets between the individual leader UEs 110L. To this end, the start time of the synchronized linear frequency modulation signal may be set for each leader UE 110L in a manner that compensates for the timing offsets between the multiple leader UEs 110L. In this manner, the TRP 170 may attempt to establish that multiple synchronized linear frequency modulation signals will be sent from multiple leader UEs 110L at the same time relative to the network clock (step 1304, Fig.12 ). It should be noted that this synchronization provides some benefits (which will be explained below) and this synchronization does not have to be considered mandatory. Two general scenarios are envisioned.

[0148] In the first scenario, it may be assumed that the leader UE 110L is not synchronized. Therefore, the leader UE 110L may be understood to send a synchronized chirp signal with some time offset relative to the network clock.

[0149] In the second scenario, it may be assumed that the leader UE 110L is synchronized. Therefore, the leader UE 110L may be understood to be transmitting synchronized chirp signals simultaneously with respect to the network clock.

[0150] In the first scenario, when the target UE 110T associates with a specific leader UE 110L for synchronous linear frequency modulation signal reception (step 1106, Fig.11 ) and access the transmission of the linear frequency modulation signal (step 1114, Fig.11 Consider that a given target UE 110T-X performs reception and measurement of a synchronous chirp signal sent by a given leader UE 110L-Y (step 1106, Fig.11 Based on the measurements, a given target UE 110T-X may estimate (step 1108, Fig.11 ) relative to the synchronization offset of a given leader UE 110L-Y. It can be seen that, considering the transmission by a given target UE 110T-X (step 1114, Fig.11 )'s access chirp signal is received (step 1206) and measured by a given leader UE 110L-Y that best performs the synchronization task.

[0151] For associating the target UE 110T with the specific leader UE 110L for receiving the synchronous linear frequency modulation signal (step 1106, Fig.11 ) and access the transmission of the linear frequency modulation signal (step 1114, Fig.11 ), involves establishing that the configuration of each synchronized linear frequency modulation signal is specific to the leader UE 110L that sent the synchronized linear frequency modulation signal. In this way, each synchronized linear frequency modulation signal of a plurality of synchronized linear frequency modulation signals received at a target UE 110T can be distinguished at the target UE 110T and associated with a specific leader UE 110L.

[0152] To distinguish the synchronized chirp signals transmitted by each of the plurality of leader UEs 110L, the TRP 170 may configure each of the leader UEs 110L to use a different start time, a different start frequency, a different chirp rate, or any combination of these parameters.

[0153] It should be noted that, from a practical point of view, using different chirp rates to distinguish the synchronous chirp signals sent by different leader UEs 110L may not be attractive. As described above, the intended target UE 110T measures the received synchronous chirp signal (step 1106, Fig.11 ). It can be seen that if each leader UE110L is used to send (step 1204, Fig.12) synchronized linear frequency modulation signals using different linear frequency modulation rates, the target UE 110T is expected to measure the received synchronized linear frequency modulation signals having various linear frequency modulation rates (step 1106, Fig.11 In order to enable the target UE 110T to measure the received synchronous frequency modulation signals with various linear frequency modulation rates (step 1106, Fig.11 ), the hardware of the target UE 110T may be used to measure the received synchronous linear frequency modulation signals having various linear frequency modulation rates (step 1106, Fig.11 It should be easy to understand that the method for measuring the received synchronous linear frequency modulation signal having only one linear frequency modulation rate (step 1106, Fig.11 ) is used to measure the received synchronous linear frequency modulation signals with various linear frequency modulation rates (step 1106, Fig.11 ) has low hardware complexity. It should be easy to understand that the method for measuring the received synchronous linear frequency modulation signal having only one linear frequency modulation rate (step 1106, Fig.11 ) is used to measure the received synchronous linear frequency modulation signals with various linear frequency modulation rates (step 1106, Fig.11 ) hardware consumes less power.

[0154] Therefore, while it is certainly possible to use different chirp rates to differentiate the synchronized linear frequency chirp signals sent by different leader UEs 110L, for practical reasons, the focus below is on the scenario where the chirp rates of all synchronized linear frequency chirp signals are the same. In such a scenario, in order to differentiate the synchronized linear frequency chirp signals sent by different leader UEs 110L, the TRP 170 may configure different leader UEs 110L to expect linear frequency synchronization signals with different start times and / or different start frequencies.

[0155] In the first case, if Fig.16 As shown, the starting frequency is used to distinguish the first synchronous linear frequency modulation signal 1601 sent by the first leader UE from the second synchronous linear frequency modulation signal 1602 sent by the second leader UE. That is, the first synchronous linear frequency modulation signal 1601 has a first starting frequency f1, and the second synchronous linear frequency modulation signal 1602 has a second starting frequency f2. It should be noted that the first synchronous linear frequency modulation signal 1601 has a starting time t, and the second synchronous linear frequency modulation signal 1602 has the same starting time t. In addition, it should be noted that the first synchronous linear frequency modulation signal 1601 has a linear frequency modulation rate α0, and the second synchronous linear frequency modulation signal 1602 has the same linear frequency modulation rate α0.

[0156] In the second case, if Fig.17 As shown, the start time is used to distinguish the first synchronized linear frequency modulation signal 1701 sent by the first leader UE from the second synchronized linear frequency modulation signal 1702 sent by the second leader UE. That is, the first synchronized linear frequency modulation signal 1701 has a first start time t1, and the second synchronized linear frequency modulation signal 1702 has a second start time t2. It should be noted that the first synchronized linear frequency modulation signal 1701 has a start frequency f, and the second synchronized linear frequency modulation signal 1702 has the same start frequency f. In addition, it should be noted that the first synchronized linear frequency modulation signal 1701 has a linear frequency modulation rate α0, and the second synchronized linear frequency modulation signal 1702 has the same linear frequency modulation rate α0.

[0157] In the third case, if Fig.18 As shown, both the starting frequency and the starting time are used to distinguish the first synchronous linear frequency modulation signal 1801 sent by the first leader UE from the second synchronous linear frequency modulation signal 1802 sent by the second leader UE. That is, the first synchronous linear frequency modulation signal 1801 has a first starting time t1 and a first starting frequency f1. The second synchronous linear frequency modulation signal 1802 has a second starting time t2 and a second starting frequency f2. It should be noted that the first synchronous linear frequency modulation signal 1801 has a linear frequency modulation rate α0, and the second synchronous linear frequency modulation signal 1802 has the same linear frequency modulation rate α0.

[0158] The target UE 110T is associated with a specific leader UE 110L for synchronous chirp signal reception (step 1106, Fig.11 ) and access the transmission of the linear frequency modulation signal (step 1114, Fig.11 ), may involve implementing a strategy including establishing a connection between a configuration of a synchronization chirp and a configuration of an access chirp. Such a connection may be shown to help a particular leader UE 110L identify which of a plurality of received access chirps are intended for the particular leader UE 110L.

[0159] For this strategy, the first option is to make the starting frequency f of the access linear frequency modulation signal access Using this first option, the target UE 110T measures the received synchronous linear frequency modulation signal (step 1106, Fig.11 ) may be that the target UE 110T acquires the synchronous linear frequency modulation signal starting frequency. The synchronous linear frequency modulation signal starting frequency may be used by the target UE 110T to determine the access linear frequency modulation signal starting frequency. For example, the target UE 110T may determine that in sending (step 1114, Fig.11) The starting frequency f of the linear frequency modulation signal to be used when the linear frequency modulation signal is connected access . Access the linear frequency modulation signal starting frequency f access The starting frequency f of the linear frequency modulation synchronization signal can be obtained from synch and constant frequency offset f const That is to say, the starting frequency f of the linear frequency modulation signal is connected access From the relation f access =f synch +f const The constant frequency offset f const The value of may be provided by the TRP 170 to the target UE 110T via control signaling before the target UE 110T enters the low power mode. const The value of may also be provided to the leader UE 110L by the TRP 170. In addition, based on the linear frequency modulation synchronization signal starting frequency f synch and constant frequency offset f const The leader UE 110L may be able to determine the starting frequency f of the access chirp signal. access . When determining the starting frequency f of the linear frequency modulation signal access Then, the leader UE 110L may measure the access chirp signal received from the target UE 110T.

[0160] For this strategy, a second option is to correlate the start time of the access chirp signal with the start time of the synchronous chirp signal. Using this second option, the target UE 110T measures the received synchronous chirp signal (step 1106, Fig.11 ) may be that the target UE 110T acquires the start time of the synchronous linear frequency modulation signal. Access linear frequency modulation signal start time t access The linear frequency modulation synchronization signal starting time t can be obtained from synch , and a constant time offset t const That is to say, the starting frequency f of the linear frequency modulation signal is connected access From the relation t access =t synch +t const The constant time offset t const The value of may be provided by TRP 170 to the target UE 110T via control signaling before the target UE 110T enters the low power mode. const The value of can also be provided to the leader UE 110L by TRP 170. In addition, based on the synchronous linear frequency modulation signal start time t synch and constant time offset tconst The leader UE 110L may be able to determine the start time t of accessing the linear frequency modulation signal. access . After determining the starting frequency t of the linear frequency modulation signal access Then, the leader UE 110L may measure the access chirp signal received from the target UE 110T.

[0161] For this strategy, a third option is to correlate the access chirp start time with the sync chirp start time and to correlate the access chirp start frequency with the sync chirp start frequency. Using this third option, the target UE 110T measures the received sync chirp signal (step 1106, Fig.11 ) may result in the target UE 110T acquiring the synchronous linear frequency modulation signal start time and the synchronous linear frequency modulation signal start frequency. Access linear frequency modulation signal start time t access and the starting frequency f of the linear frequency modulation signal access It can be determined from the relationship discussed above. More generally, the start time of the linear frequency modulation signal is t access It can be the start time of the synchronous linear frequency modulation signal t synch and the synchronous linear frequency modulation signal starting frequency f synch Similarly, the starting frequency f of the linear frequency modulation signal is connected access It can be the start time of the synchronous linear frequency modulation signal t synch and the synchronous linear frequency modulation signal starting frequency f synch function.

[0162] It should be noted that in all three options described above, a portion of the configuration of the access linear frequency modulation signal can be inferred at the target UE 110T from the measurement results obtained on the received synchronous linear frequency modulation signal. It should be clear that in this case, the inferred portion of the access linear frequency modulation signal configuration does not need to be indicated to the target UE 110T before the target UE 110T enters the low power mode.

[0163] Various aspects of the present application relate to a low complexity receiver 2000 (see Fig. 20), the low complexity receiver enables the target UE 110T to extract timing from the received synchronous linear frequency modulation signal when the target UE 110T is operating in the low power mode. The processing of the received synchronous linear frequency modulation signal by the receiver 2000 can be understood as being based on matched filtering of the received synchronous linear frequency modulation signal. The process of matched filtering is sometimes referred to as "pulse compression". The process of matched filtering is known to be implemented in the RF domain, thereby reducing complexity and power consumption relative to the processing performed in the baseband domain. In order to operate correctly, the matched filter 2004 arranged to implement the matched filtering processing will match the synchronous linear frequency modulation signal sent by the leader UE 110L. Therefore, it is expected that the target UE 110T will receive at least a portion of the synchronous linear frequency modulation signal configuration (e.g., an indication of the linear frequency modulation rate) before the target UE 110T enters the low power mode. In response to receiving at least a portion of the synchronous linear frequency modulation signal configuration, the target UE 110T can adjust the matched filter 2004 for use in the low power mode. In general, it can be shown that when a matched filter is fed with a signal that has been pre-matched to the matched filter, the output envelope will be shaped in the time domain to resemble a sinc function. The timing information of the transmitted linear frequency modulation signal can be extracted by detecting the timing of the peaks of the output envelope. Alternatively, the timing information can be extracted by detecting the beat frequency of the synchronous linear frequency modulation signal after multiplying the received synchronous linear frequency modulation signal with the conjugate of the transmitted synchronous linear frequency modulation signal and applying a low pass filter. In some embodiments, detecting the beat frequency of the synchronous linear frequency modulation signal can involve performing an FFT operation on the sampled, RF processed signal.

[0164] consider Fig.19 An example is shown in which there are two leader UEs 110L1, 110L2 near a target UE 110T in low power mode. The first leader UE 110L1 is associated with a synchronized linear frequency modulation signal having a first starting frequency f1 and a first coverage area 1901. The second leader UE 110L2 is associated with a synchronized linear frequency modulation signal having a second starting frequency f2 and a second coverage area 1902. For the sake of this example, it can be assumed that the two synchronized linear frequency modulation signals start at time zero, i.e., t1=t2=0. For the sake of this example, it can also be assumed that the starting frequencies (i.e., f1 and f2) of the synchronized linear frequency modulation signals transmitted by the two leader UEs 110L1, 110L2 are completely separated.

[0165] Fig. 20The basic structure of two leader UEs 110L1, 110L2 and a target UE 110T and a representation of a synchronous linear frequency modulation signal are shown. The first leader UE 110L1 has a first linear frequency modulation generator 2002-1 for generating a synchronous linear frequency modulation signal based on a defined configuration. The second leader UE 110L2 has a second linear frequency modulation generator 2002-2 for generating a synchronous linear frequency modulation signal based on a defined configuration. The two synchronous linear frequency modulation signals are shown to have a common linear frequency modulation rate α0. At the target UE 110T, a matched filter 2004 is matched to a signal having a common linear frequency modulation rate α0, a zero start time and a specific start frequency. The output from the matched filter 2004 is passed to a peak detection unit 2006. The peak detection unit 2006 can be used to detect the peak of the envelope of the output from the matched filter 2004.

[0166] Fig.21 Shows Fig. 20 An exemplary envelope of the output of the matched filter 2004 in FIG. It can be observed that there is a peak 2101 near Another peak 2102 is approaching It can also be observed that the peaks are completely separated because the starting frequencies f1 and f2 of the synchronous linear frequency modulation signals are completely separated, that is, the absolute difference |f2-f1| between the starting frequencies of the synchronous linear frequency modulation signals is large enough so that the individual sinc functions do not interfere with each other.

[0167] Fig. 22 2202) a signal. The target UE 110 may process (step 2204) the received signal using a matched filter 2004 to produce a matched filter output having an envelope (see FIG. Fig.21 ). Then, the target UE 110 may use the peak detection unit 2006 to obtain (step 2206) the measurement timing for the peak value. The measurement timing may be expressed as and It should be noted that it can be shown in, is the synchronization offset between the target UE 110T and the leader UE 110Li, ToF i is the flight time of the wireless link between the leader UE 110Li and the target UE 110T. When the ToF is assumed to be small, the ToF term can be ignored due to the short transmission distance, and can be used Estimates Where i = 1, 2. It should be noted that the synchronization offset estimation The first term in the expression is obtained through measurement, the second It can be determined based on the synchronous linear frequency modulation signal configuration information. In addition, since the starting frequencies f1 and f2 of the synchronous linear frequency modulation signal are completely separated, the target UE 110T can determine which peak corresponds to which starting frequency. Then, the target UE 110T can select one of the peaks and associate the selected peak with the leader UE 110L corresponding to the selected peak. For example, the target UE 110T can select the peak with the largest envelope. The peak with the largest envelope may correspond to the nearest leader UE 110L with the smallest ToF. Selecting the peak with the largest envelope can be shown to obtain a better synchronization offset estimate because ToF plays an important role in the synchronization offset estimate. appears as an additive error.

[0168] After selecting (step 2208) the peak value, the target UE 110T may be considered to have provided itself with some configuration information for accessing the linear frequency modulation signal. For the first example, it may be assumed that the first peak value has been selected and the first case is being used. Recall that in the first case, if Fig.16 As shown, the starting frequency is used to distinguish a first synchronous linear frequency modulation signal 1601 sent by a first leader UE from a second synchronous linear frequency modulation signal 1602 sent by a second leader UE.

[0169] After selecting (step 2208) the peak, the target UE 110T may transmit (step 2210) an access chirp signal having a starting frequency based on the constant frequency f const It is determined by adding the starting frequency f1 obtained by selecting the peak value. That is, f access =f1+f const .

[0170] After acquiring measurements of the access chirp signal, the first leader UE 110L1 may determine that there is a target UE 110T in a low power mode nearby that has decided to associate with the first leader UE 110L1.

[0171] It should be noted that after the target UE 110T has obtained (step 2212) an estimate of the synchronization offset between itself and the selected leader UE 110Li The target UE 110T may then modify (step 2214) the clock at the target UE 110T to compensate for the synchronization offset. To do this, the target UE 110T changes its time (step 2214) to Among them, t ′ is the time after modification, t is the time before modification, is an estimate of the synchronization offset between the target UE 110T and the selected leader UE 110Li.

[0172] Various aspects of the present application relate to access linear frequency modulation signal configuration, access linear frequency modulation signal transmission and access linear frequency modulation signal measurement. The access linear frequency modulation signal is sent by the target UE 110T (e.g., step 2210, Fig. 22 ), and is measured by the leader UE 110L. The configuration parameters for accessing the linear frequency modulation signal may include: linear frequency modulation rate; start time; duration; start frequency; and transmit power.

[0173] In operation, the TRP 170 may send configuration parameters for accessing the linear frequency modulation signal to the leader UE 110L and the target UE 110T before entering the low power mode. In one example, the TRP 170 may send the configuration parameters using control signaling such as RRC configuration signaling. At the target UE 110T, one or more configuration parameters for accessing the linear frequency modulation signal may be inferred based on measurements of the received synchronous linear frequency modulation signal.

[0174] In operation in the low power mode, the target UE 110T sends based on the configuration (e.g., step 2210, Fig. 22 ) to access the linear frequency modulation signal.

[0175] Fig.23 Exemplary steps in a method of operation for a given leader UE 110L for accessing a chirp signal are shown.

[0176] Initially, the given leader UE 110L receives (step 2302) configuration parameters for access chirps for a plurality of neighboring target UEs 110T from the TRP 170. The given leader UE 110L may also receive (step 2302) configuration parameters for synchronization chirps from the TRP 170.

[0177] The given leader UE 110L may then receive (step 2304) the access chirp signal transmitted by the neighboring target UE 110T.

[0178] The given leader UE 110L may then make measurements of the received access chirp (step 2306).

[0179] Based on the measurements, the given leader UE 110L may determine (step 2308) an access chirp corresponding to each of the target UEs 110T that have selected to associate with the given leader UE 110L.

[0180] The given leader UE 110L may then send (step 2310) the measurement results corresponding to the target UEs 110T that have been selected to be associated with the given leader UE 110L to the TRP 170 for further processing.

[0181] For the transmission of access linear frequency modulation signals, it can be shown that the transmission of access linear frequency modulation signals of different target UEs 110T (step 2210, Fig. 22 ) is advantageously arranged to occur in different domains. The different domains may be shown to enable the leader UE 110L to perform measurements based on the received access linear frequency modulation signal (step 2306, Fig.23 ) to determine the corresponding relationship between the access linear frequency modulation signal and the target UE 110.

[0182] This arrangement may involve assigning different access linear frequency modulation signal configuration parameters such as start time, start frequency and / or linear frequency modulation rate to different target UEs 110T. It can be seen that multiple mappings can be defined. Each mapping can be understood as associating a specific set of access linear frequency modulation signal configuration parameters with a specific target UE 110T. The mapping can be indexed using the UE ID that has been associated with the specific target UE 110T. In some cases discussed above, the start time and / or start frequency of the access linear frequency modulation signal can be inferred at the target UE 110T based on the processing measurement of the received synchronous linear frequency modulation signal. It should be noted that when multiplexing signals from multiple target UEs 110T, the inferred start time and / or inferred start frequency are candidates that are not suitable for use. However, when multiplexing signals from multiple target UEs 110T, the linear frequency modulation rate domain is always available.

[0183] For the first example, recall that in the first case, if Fig.16 As shown, the starting frequency can be used to distinguish Fig.19 The first leader UE 110L sends a first synchronous linear frequency modulation signal and Fig.19 A second synchronous linear frequency modulation signal is sent by the second leader UE 110L2. Consider the case where the starting frequency of the access linear frequency modulation signal is determined based on the measurement of the synchronous linear frequency modulation signal at the target UE 110T. In this case, it can be shown that the starting frequency of the access linear frequency modulation signal may not be used for multiplexing the access linear frequency modulation signal transmission between multiple target UEs 110T. However, the starting time and the linear frequency modulation rate can be used for multiplexing the access linear frequency modulation signal transmission between multiple target UEs 110T. In addition, it is important to note that although different target UEs 110T can use various time-frequency resources for access linear frequency modulation signal transmission, since the transmission is short-distance, these resources can be reused throughout the network.

[0184] After the target UE 110T sends an access chirp signal (step 2210, Fig. 22 ) after which the nearby leader UE110L receives (step 2304, Fig.23 ) accesses the linear frequency modulation signal and performs measurement (step 2306, Fig.23 ) to obtain the configuration parameters of the received access linear frequency modulation signal. The nearby leader UE 110L may also obtain various other parameters, which will be mentioned below. Based on the configuration parameters obtained for the received access linear frequency modulation signal, the leader UE 110L may determine whether the received access linear frequency modulation signal is for the leader UE 110L. For example, in the example discussed above, the target UE 110T may select the first leader UE 110L1 and therefore use the access linear frequency modulation signal starting frequency based on the first starting frequency f1. After receiving the access linear frequency modulation signal at the second leader UE 110L2, the second leader UE 110L2 may determine that the access linear frequency modulation signal starting frequency is based on the first starting frequency f1. Based on determining that the access linear frequency modulation signal starting frequency is based on the first starting frequency f1, the second leader UE 110L2 may ignore the access linear frequency modulation signal. After detecting the access linear frequency modulation signal, the first leader UE 110L1 may determine that the target UE 110T in the surrounding area has chosen to associate with the first leader UE 110L1. It is expected that power consumption is not an issue for the leader UE 110L. Therefore, the measurements made at the leader UE 110L (step 2306, Fig.23 ). Multiple chirp rates may also be measured (step 2306, Fig.23 ).

[0185] The measurements performed at a given leader UE 110L may enable the given leader UE 110L to determine a timing estimate for each target UE 110T associated with the given leader UE 110L. It may be shown that the ToF of the link between the given leader UE 110L and the target UE 110T may be obtained from the timing estimate. It should be noted that only in processing (step 2202, Fig. 22 ) after the target UE 110T has modified (step 2214, Fig. 22 )In the case of its timing, the acquisition of ToF of the link can be considered accurate.

[0186] The measurements performed at a given leader UE 110L may also enable the given leader UE 110L to determine the angle of arrival (AoA) of the access chirp signal transmitted by each target UE 110T associated with the leader UE 110L.

[0187] In determining (step 2308, Fig.23 ) corresponding to the access chirp signals of each target UE 110T that has been selected to be associated with the given leader UE 110L, the given leader UE 110L sends to the TRP 170 (step 2310, Fig.23 ) corresponds to the measurement results of the target UE 110T associated with the given leader UE 110L that has been selected for further processing.

[0188] For the second example, we can assume that Fig.19 The target UE 110T has selected the first leader UE 110L1 after the synchronous linear frequency modulation signal measurement. Again, it can be assumed that the first case is used, such as Fig.16 As shown. Recall that in the first case, the starting frequency can be used to distinguish Fig.19 The first leader UE 110L sends a first synchronous linear frequency modulation signal and Fig.19 The second leader UE 110L2 sends a second synchronous linear frequency modulation signal.

[0189] The target UE 110T is expected to use f1+f const As the starting frequency f of the transmitted access linear frequency modulation signal access Prior to entering the low power mode, the target UE 110T may have received f in the access chirp signal configuration. const The value of f1 may be obtained by the target UE 110T based on a measurement of the synchronous linear frequency modulation signal received from the first leader UE 110L1. In this example, the value α1 may be used to represent the linear frequency modulation rate of the access linear frequency modulation signal assigned to the target UE 110T. In addition, the value t1 may be used to represent the start time of the access linear frequency modulation signal assigned to the target UE 110T. Fig.24 As shown, the target UE 110T may send a signal with a chirp rate α1 and a starting frequency f access =f1+f const And the access linear frequency modulation signal with starting time t1.

[0190] It is expected that both leader UEs 110L1, 110L2 will receive the transmitted access chirp signal and perform measurements. The results of the measurements at the two leader UEs 110L1 and 110L2 may reveal the starting frequency f of the received access chirp signal. access =f1+f const Therefore, the second leader UE 110L2 can identify that the target UE 110T sending the access linear frequency modulation signal has not chosen to associate with the second leader UE 110L2. Recall that the first starting frequency f1 is used as the starting frequency of the synchronous linear frequency modulation signal sent by the first leader UE 110L1. It can be seen that the target UE 110 will access the starting frequency f1 of the linear frequency modulation signal. access Based on the first starting frequency f1, to indirectly indicate that the target UE 110 intends to associate with the first leader UE 110L1. After the measurement, the first leader UE 110L1 can determine that there is a target UE 110T nearby that wishes to associate with the first leader UE 110L1. By using the measurement results, the first leader UE 110L1 can also obtain the ToF of the link between the first leader UE 110L1 and the target UE 110T. By using the measurement results, the first leader UE 110L1 can also obtain the AoA of the access linear frequency modulation signal received from the target UE 110T. Subsequently, the first leader UE 110L1 can send an indication of the measurement of ToF and the configured AoA with α1, f1 and t1 to the TRP 170. Since the TRP 170 maintains the configuration parameters for accessing chirp signals for different target UEs 110T, the TRP 170 can infer from the configuration reported with the measurement (eg, α1, f1, and t1) that the measurement value corresponds to the target UE 110T.

[0191] Various aspects of the present application relate to determining a timing advance (TA) of a target UE 110T relative to a TRP 170 when the target UE 110T operates in a low power mode. Determining the TA may be based on measurements of an access chirp signal performed by a leader UE 110L associated with the target UE 110T.

[0192] exist Fig.25 In FIG. 1 , there is a TRP 170, a target UE 110T, and a leader UE 110L1 associated with the target UE 110T itself. It can be assumed that the synchronization linear frequency modulation signal and the access linear frequency modulation signal have been sent and measured as described above. It can be seen that the TRP 170 has received the measurement results of the access linear frequency modulation signal sent by the target UE 110T from the leader UE 110L1. Fig.25, the TRP 170, the target UE 110T and the leader 110L1 may be viewed as vertices of a triangle.

[0193] The first link (sidelink) between the target UE 110T and the leader UE 110L1 can be associated with a value of ToF of the first link (labeled as "a"). The value of ToF can be understood as being obtained by the leader UE 110L1 based on the measurement of the access linear frequency modulation signal. It is also expected that the leader UE 110L1 has reported the ToF to the TRP 170. It can be seen that the TRP 170 maintains the value of a after receiving the report.

[0194] In addition, a second link between TRP 170 and leader UE 110L1 may be associated with a value of ToF for the second link (labeled "b"). Since leader UE 110L1 is already connected to TRP 170, it may be assumed that TRP 170 has already determined the value of b (e.g., the value of b may have been measured during an initial access procedure performed at leader UE 110L1). Recall that the AoA of the access linear frequency modulation signal transmitted by target UE 110T may be measured at leader UE 110L1. Fig.25 θ formed between the first link and the second link is shown in . The value of the angle θ may be determined based on the value of AoA reported by the leader UE 110L1 to the TRP 170 .

[0195] The third link between TRP 170 and target 110T may be associated with a value of the ToF of the third link (labeled "x"). The TA of target UE 110T relative to TRP 170 may be equal to the ToF of the third link, x. Thus, by determining the value of x given the values ​​of a, b, and θ, the value of the TA of target UE 110T relative to TRP 170 may be understood to have been determined.

[0196] Various aspects of the present application involve determining the value of x using the known law of cosines given the values ​​of a, b, and θ. This formula takes into account the relative orientation of the nodes in the network. The exact value of angle θ may not be available. In this case, TRP 170 may obtain a range of values ​​for angle θ, for example, [θ1, θ2], where θ1 is one end of the range and θ2 is the other end of the range. When the end of the range of values ​​for angle θ is available, the value of x may be used. Approximate calculation, where is the value representing the range. For example, you can use the average of the endpoints of the range, i.e. As a value representing the range.

[0197] Various aspects of the present application relate to signaling exchanges. Fig.26 An exemplary signal flow diagram of signal flow between UE 110L, TRP 170 and target UE 110T is shown. Initially, UE 110L sends (step 2601) a capability report to TRP 170. Subsequently, TRP 170 receives (step 2602) a capability report from UE 110L. It should be noted that at this time, UE 110L is not yet a leader UE. Based on the capability report, TRP 170 may select (step 2604) UE 110L as a leader UE. As previously described, a leader does not have to be a UE. Instead, a leader may be a network node with capabilities suitable for a leader. For simplicity, throughout this application, a leader is referred to as a leader UE.

[0198] In general, the TRP 170 may select (step 2604) a leader UE 110L based on status, characteristics, and capabilities (e.g., location, synchronization status, and transmit power capabilities). There may be situations where it is preferred to have one or more leader UEs 110L in different geographic parts of the network. In such cases, the location of the leader UE 110L may be a factor in the leader UE selection (step 2604). To this end, it is contemplated that all potential leader UEs 110L provide capability reports to the TRP 170.

[0199] In response to the selection (step 2604), the TRP 170 may send (step 2606) a selection indication to the leader UE 110L to indicate that the leader UE 110L has been selected. The selection indication may be sent (step 2606) to the leader UE 110L via control signaling (e.g., RRC signaling or MAC-CE). Subsequently, the TRP 170 sends (step 2608) information for configuring the synchronous linear frequency modulation signal and the access linear frequency modulation signal to the leader UE 110L. The TRP 170 may also send (step 2608) information for configuring the synchronous linear frequency modulation signal and the access linear frequency modulation signal to the target UE 110T before the target UE 110T enters a low power mode. For example, the sending of the configuration information (step 2608) may be accomplished using RRC configuration signaling. As in Fig.23 As discussed in , the leader UE 110L receives (step 2302) a chirp signal configuration.

[0200] The leader UE 110L may then send (step 2610) a synchronous chirp signal based on the defined configuration. Fig. 22 As discussed in , the target UE 110T receives (step 2202) a synchronous linear frequency modulation signal. Fig.11As discussed in , the target UE 110T measures the received synchronous linear frequency modulation signal (step 1106).

[0201] As a measure of the synchronous linear frequency modulation signal (see Fig. 22 As a result of steps 2204, 2206, and 2208 in the above process, the target UE 110T may obtain (step 2212) an estimate of the synchronization offset and modify (step 2214) the clock at the target UE 110T. In addition, a portion of the access linear frequency modulation signal configuration may be obtained from processing (steps 2204, 2206, 2208, Fig. 22 ) is inferred from the measurement. The target UE 110T sends (step 2210, Fig. 22 ) accesses the linear frequency modulation signal. The leader UE110L receives (step 2304, Fig.23 ) accesses the linear frequency modulation signal and performs measurement (step 2306, Fig.23 , step 1206, Fig.12 ) and prepares a measurement report. Then, the leader UE 110L sends (step 2310, Fig.23 ) measurement report. TRP170 receives (step 2612) the measurement report and performs further processing.

[0202] Various aspects of the present application relate to modifying (step 2214, Fig. 22 )The clock at the target UE110T can previously estimate the details of the UE clock parameters.

[0203] Specifically, consider the linear model t TRP =βt UE +γ, where the linear model establishes the time t at the target UE 110T UE (broadly referred to as the "UE clock") and the time t at TRP 170 TRP The linear model includes model parameters β and γ. Fig. 27 A linear model is shown. In the linear model, the model parameter β is used to represent the rate of change of the difference between the frequency of the clock at TRP170 and the frequency time of the clock at the target UE 110T. In the linear model, the model parameter γ is used to represent the constant clock drift. Ideally, it is preferred to have β=1 and γ=0. However, this is not the case in reality. This deviation from the ideal provides an impetus for performing synchronization to estimate the synchronization offset and then compensate for the synchronization offset. Various aspects of the present application relate to estimating model parameters β and γ based on multiple measurements. Various aspects of the present application relate to the target UE 110T in low power mode receiving (step 2202, Fig. 22) synchronous linear frequency modulation signal is obtained (step 2212, Fig. 22 )Estimate of synchronization offset. The target UE 110T can be used to stack multiple measurements and perform linear regression to find the model parameters β and γ. It can be shown that the larger the deviation between the estimated rate of change β of the TRP / UE frequency difference and the ideal rate of change of the TRP / UE frequency difference |β-1|, the faster the synchronization offset grows in time. It can be seen that in this case, synchronization should occur more frequently. Therefore, the frequency with which synchronization is performed on the target UE 110T can be adjusted in a manner proportional to the estimate |β-1|.

[0204] It should be understood that one or more steps of the method embodiments provided herein can be performed by corresponding units or modules. For example, data can be sent by a sending unit or a sending module. Data can be received by a receiving unit or a receiving module. Data can be processed by a processing unit or a processing module. The corresponding units / modules can be hardware, software, or a combination thereof. For example, one or more units / modules can be integrated circuits, such as field programmable gate arrays (FPGAs) or application specific integrated circuits (ASICs). It should be understood that if these modules are software, these modules can be retrieved in whole or in part by a processor as needed, retrieved individually or collectively for processing, retrieved in one or more instances as needed, and these modules themselves can include instructions for further deployment and instantiation.

[0205] Although the combination of features is shown in the illustrated embodiments, it is not necessary to combine all the features to achieve the advantages of various embodiments of the present invention. In other words, the system or method designed according to the embodiment of the present invention does not necessarily include all the features shown in any one of the figures or all the parts schematically shown in the figures. In addition, the selected features of an exemplary embodiment can be combined with the selected features of other exemplary embodiments.

[0206] Although the present invention has been described with reference to illustrative embodiments, this description is not to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments and other embodiments of the present invention will be apparent to those skilled in the art with reference to this description. Therefore, the appended claims are intended to cover any such modifications or embodiments.

Claims

1. A method for performing at a first device, the method comprising: receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration comprising configuration information of a first linear frequency modulation signal; When the first device is in a low power operation mode: receiving the first chirp signal from a second device; measuring the first chirp signal to obtain an estimated synchronization offset between a first clock at the first device and a second clock at the second device; The first clock is modified based on the estimated synchronization offset.

2. The method according to claim 1, characterized in that The linear frequency modulation signal configuration includes configuration information of a second linear frequency modulation signal, and the method further includes sending the second linear frequency modulation signal according to the configuration information of the second linear frequency modulation signal.

3. The method according to claim 2, further comprising: A second chirp configuration parameter is inferred from the measurement of the first chirp, wherein the transmitting the second chirp comprises transmitting the second chirp in accordance with the second chirp configuration parameter.

4. The method according to any one of claims 1 to 3, characterized in that The measuring the first linear frequency modulation signal includes applying a matched filter to the received first linear frequency modulation signal.

5. The method according to any one of claims 1 to 4, characterized in that The measuring the first linear frequency modulation signal includes acquiring a beat frequency of the first linear frequency modulation signal.

6. A first device, comprising: First Clock; Receiver for: receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration comprising configuration information of a first linear frequency modulation signal; receiving the first chirp signal from a second device; Memory, which stores instructions; The processor performs the following operations by executing the instructions when the first device is in a low power operation mode: measuring the first chirp signal to obtain an estimated synchronization offset between the first clock and a second clock at the second device; The first clock is modified based on the estimated synchronization offset.

7. A method for performing at a first device, the method comprising: receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration comprising configuration information of a first linear frequency modulation signal; When the second device is in low power operation mode: sending the first linear frequency modulation signal to the second device according to the configuration information of the first linear frequency modulation signal; receiving a second chirp signal from the second device; obtaining a measurement of the second chirp signal to determine that the second chirp signal is intended for the first device; Based on the measurement of the second chirp signal, a measurement report is sent to a third device.

8. The method according to claim 7, further comprising: A capability report is sent to the third device.

9. The method according to claim 8, characterized in that The capability report includes an indication of a location of the first device.

10. The method according to claim 8 or 9, characterized in that: The capability report includes an indication of a synchronization status of the first device.

11. The method according to any one of claims 8 to 10, characterized in that: The capability report includes an indication of the transmit power capabilities of the first device.

12. The method according to any one of claims 7 to 11, further comprising: Before the second device enters a low power mode and before the sending of the first linear frequency modulation signal, the configuration information of the first linear frequency modulation signal is sent to the second device.

13. The method according to any one of claims 7 to 12, further comprising: Before the second device enters the low power mode, configuration information of the second linear frequency modulation signal is sent to the second device.

14. A first device, comprising: Receiver for: receiving a linear frequency modulation signal configuration, the linear frequency modulation signal configuration comprising configuration information of a first linear frequency modulation signal; receiving a second chirp signal from a second device; a transmitter, configured to transmit the first linear frequency modulation signal to the second device according to the configuration information of the first linear frequency modulation signal when the second device is in a low power operation mode; Memory, which stores instructions; The processor performs the following operations by executing the instructions when the second device is in a low power operation mode: obtaining a measurement of the second chirp signal to determine that the second chirp signal is intended for the first device; Based on the measurement of the second chirp signal, a measurement report is sent to a third device using the transmitter.

15. A method comprising: before the second device enters the low power mode, sending, at the first device, configuration details of the first chirp signal to the second device; sending configuration details of a second chirp signal to a third device; receiving, from the third device, a report comprising measurements of the first chirp signal made at the third device; The measurements are processed.

16. The method according to claim 15, further comprising: receiving a capability report from the third device; selecting the third device to send the second linear frequency modulation signal to the second device based on the content of the capability report; An indication is sent to the third device that the third device has been selected.

17. The method according to claim 15 or 16, further comprising: The configuration details of the second chirp signal are sent to the second device.

18. The method according to any one of claims 15 to 17, further comprising: The configuration details of the first chirp signal are sent to the third device.

19. A first device, comprising: Transmitter for: before the second device enters the low power mode, sending configuration details of the first chirp signal to the second device; sending configuration details of a second chirp signal to a third device; a receiver for receiving, from the third device, a report comprising measurements of the first chirp signal made at the third device; Memory, which stores instructions; A processor processes the measurements by executing the instructions.

20. A non-transitory computer-readable medium storing a program executed by a processor, the program comprising instructions for executing the method according to any one of claims 1 to 5, 7 to 13, and 15 to 18.

21. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to perform the method according to any one of claims 1 to 5, 7 to 13 and 15 to 18.

22. An apparatus comprising a processor, the processor being configured to cause the apparatus to perform the method according to any one of claims 1 to 5, 7 to 13, and 15 to 18.

23. A processor of a device, the processor being configured to cause the device to perform the method according to any one of claims 1 to 5, 7 to 13, and 15 to 18.

24. A system comprising: A first device, configured to send a first linear frequency modulation signal; The second device is configured to receive the first linear frequency modulation signal, obtain an estimated synchronization offset between a first clock at the first device and a second clock at the second device, and send a second linear frequency modulation signal to the first device to indicate an association between the first device and the second device.

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