Triggering timing synchronization in non-terrestrial networks

Abstract

The present disclosure relates to a 5G or 6G communication system supporting a higher data transmission rate. A method of a user equipment (UE), the method comprising: receiving first information from a base station (BS), the first information comprising satellite assistance information for a target satellite; receiving second information from the BS, the second information including timing information, where the timing information includes at least one of a start time and a duration for the synchronization operation; determining whether a synchronization operation that does not require a random access channel (RACH-less) is configured; and initiating a synchronization operation by performing a random access (RA) procedure when it is determined that the RACH-less synchronization operation is not configured based on the satellite assistance information and the timing information.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication systems, and more particularly, to triggering timing synchronization in a non-terrestrial network (NTN). Background Art

[0002] 5G mobile communication technology defines a wide range of frequency bands, making high transmission rates and new services possible, and can be implemented not only in "below 6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands called millimeter waves including 28 GHz and 39 GHz. In addition, in order to achieve a transmission rate that is fifty times faster than 5G mobile communication technology and an ultra-low latency that is one-tenth of 5G mobile communication technology, the implementation of 6G mobile communication technology in the terahertz frequency band (for example, the 95 GHz to 3 THz frequency band) (called a super 5G system) has been considered.

[0003] In the early stages of 5G mobile communication technology development, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and massive machine type communications (mMTC), standardization has been ongoing on the following technologies: beamforming and massive multiple-input multiple-output (MIMO) for reducing radio wave path loss and increasing radio wave transmission distance in millimeter waves; parameter sets supporting dynamic operations for efficient utilization of millimeter wave resources and time slot formats (e.g., operating multiple subcarrier spacings); initial access technology for supporting multi-beam transmission and wide frequency bands; definition and operation of bandwidth parts (BWPs); new channel coding methods such as low-density parity-check (LDPC) codes for large amounts of data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, with respect to services supported by 5G mobile communication technology, the industry is continuously discussing improvements and performance enhancements on initial 5G mobile communication technology, and has completed physical layer standardization on technologies such as: V2X (Vehicle-to-Everything) for assisting driving decisions based on information about the location and status of a vehicle sent by a vehicle and for improving user convenience, NR-U (New Radio Unlicensed) for system operations that comply with various regulatory-related requirements in unlicensed frequency bands, NR UE energy saving, non-terrestrial network (NTN) for UE satellite direct communication for ensuring coverage in areas where communication with terrestrial networks is not possible, and positioning.

[0005] In addition, the standardization of air interface architecture / protocols for technologies such as the Industrial Internet of Things (IIOT) for supporting new services through interworking and integration with other industries; Integrated Access and Backhaul (IAB) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner; Mobility enhancements including conditional handover and dual active protocol stack (DAPS) handover; and two-step random access (two-step RACH for NR) for simplifying the random access process. At the same time, the standardization of system architecture / services for technologies such as the 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software defined network (SDN) technologies; and mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, an exponentially growing number of connected devices will be connected to the communication network, and it is therefore expected that enhanced functions and performance of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research on the following technologies is on the agenda: extended reality (XR) for efficient support of augmented reality (AR), virtual reality (VR), mixed reality (MR), etc.; 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communication.

[0007] Fifth generation (5G) or New Radio (NR) mobile communications have gained momentum recently, with increasing global technical activities in the industry and academia on various candidate technologies. Candidate implementations of 5G / NR mobile communications include: massive antenna technology from traditional cellular bands to high frequency bands to provide beamforming gain and support increased capacity, new waveforms (e.g., new radio access technologies (RATs)) to flexibly adapt to various services / applications with different requirements, and new multiple access schemes to support massive connectivity. Summary of the invention

[0008] Solutions to the problem

[0009] A user equipment (UE) includes: a transceiver configured to: receive first information from a base station (BS), the first information including satellite assistance information for a target satellite, and receive second information from the BS, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation; a processor operably connected to the transceiver, the processor configured to: determine whether a synchronization operation without a random access channel (RACH-less) is configured, and when it is determined that the RACH-less synchronization operation is not configured, start the synchronization operation by performing a random access (RA) procedure based on the satellite assistance information and the timing information.

[0010] A method of a user equipment (UE), the method comprising: receiving first information from a base station (BS), the first information comprising satellite assistance information of a target satellite; receiving second information from the BS, the second information comprising timing information, wherein the timing information comprises at least one of a start time and a duration for a synchronization operation; determining whether a synchronization operation without a random access channel (RACH-less) is configured; and when it is determined that the RACH-less synchronization operation is not configured, starting the synchronization operation by performing a random access (RA) procedure based on the satellite assistance information and the timing information.

[0011] A base station (BS) includes: a processor; and a transceiver operably connected to the processor, the transceiver being configured to: send first information to a user equipment (UE), the first information including satellite assistance information for a target satellite, and send second information to the UE, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation; send third information to the UE, the third information indicating whether a synchronization operation without a random access channel (RACH-less) is configured, wherein: when it is indicated that the RACH-less synchronization operation is not configured, the synchronization operation is initiated based on the satellite assistance information and the timing information.

[0012] A method of a base station (BS), the method comprising: sending first information to a user equipment (UE), the first information comprising satellite assistance information for a target satellite, and sending second information to the UE, the second information comprising timing information, wherein the timing information comprises at least one of a start time and a duration for a synchronization operation; sending third information to the UE, the third information indicating whether a synchronization operation without a random access channel (RACH-less) is configured, wherein: when it is indicated that the RACH-less synchronization operation is not configured, the synchronization operation is initiated based on the satellite assistance information and the timing information. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more fully understand the content and beneficial effects of the present disclosure, the following description is now made in conjunction with the accompanying drawings, wherein the same reference numerals represent the same components: Figure 1 An example of a wireless network according to an embodiment of the present disclosure is shown; Figure 2 An example of a gNB according to an embodiment of the present disclosure is shown; Figure 3 An example of a UE according to an embodiment of the present disclosure is shown; Figure 4 and Figure 5 shows examples of wireless transmit and receive paths according to the present disclosure; Figure 6 An example of NTN communication according to an embodiment of the present disclosure is shown; Figure 7 An example of an NTN quasi-terrestrial fixed cell according to an embodiment of the present disclosure is shown; Figure 8 A flow chart showing UE behavior of sending a TA report MAC CE with HARQ feedback according to an embodiment of the present disclosure; Fig. 9 A flow chart showing UE behavior for NE-requested TA reporting in RACH in RRC connected state according to an embodiment of the present disclosure; Fig.10 A flowchart showing a UE behavior of sending a TA report MAC CE requested by a DCI or MAC CE in an RRC connected state according to an embodiment of the present disclosure; Fig.11 A flow chart showing UE behavior of sending a TA report in a UE information procedure in an RRC connected state according to an embodiment of the present disclosure; Fig.12 A flowchart showing a UE behavior of periodically or semi-persistently sending a TA report in an RRC connected state according to an embodiment of the present disclosure; Fig.13 A flowchart showing UE behavior for NW-requested RA in RRC connected state according to an embodiment of the present disclosure; Fig.14 A flow chart showing UE behavior for event-triggered RA in RRC connected state according to an embodiment of the present disclosure; Fig.15 A flowchart of a UE method for TA reporting in NTN according to an embodiment of the present disclosure is shown; Fig.16 The structure of the UE according to the embodiment of the present disclosure is shown; Fig.17 The structure of a base station according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0014] The present disclosure relates to wireless communication systems, and more particularly, to TA reporting in NTNs.

[0015] In one embodiment, a user equipment (UE) is provided. The UE includes a transceiver configured to: receive first information from a base station (BS), the first information including satellite assistance information for a target satellite, and receive second information from the BS, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation. The UE also includes a processor operably connected to the transceiver, the processor configured to: determine whether a synchronization operation without a random access channel (RACH-less) is configured, and if it is determined that the RACH-less synchronization operation is not configured, start the synchronization operation by performing a random access (RA) procedure based on the satellite assistance information and the timing information.

[0016] In one embodiment, a BS is provided. The BS includes a processor and a transceiver operably connected to the processor. The transceiver is configured to: send first information to a UE, the first information including satellite assistance information for a target satellite, send second information to the UE, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation, and send third information to the UE, the third information indicating whether a RACH-less synchronization operation is configured. Wherein, when it is indicated that the RACH-less synchronization operation is not configured, the synchronization operation is initiated based on the satellite assistance information and the timing information.

[0017] In another embodiment, a method of a user equipment (UE) is provided. The method includes: receiving first information from a BS, the first information including satellite assistance information for a target satellite; receiving second information from the BS, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation; determining whether a synchronization operation without a random access channel (RACH-less) is configured; and if it is determined that the RACH-less synchronization operation is not configured, starting the synchronization operation by performing a random access (RA) procedure based on the satellite assistance information and the timing information.

[0018] Other technical features may be apparent to those skilled in the art from the following drawings, descriptions and claims.

[0019] Before starting the following detailed description, it may be helpful to elaborate on the definitions of some words and phrases used in this patent document. "Connection" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not these elements are in physical contact with each other. The terms "send", "receive" and "communication" and their derivatives cover direct and indirect communication. The terms "include" and "include" and their derivatives represent including but not limited to. The term "or" is inclusive, meaning and / or. The phrase "associated with..." and its derivatives mean including, included in, interconnected with, included in, connected or connected to, connected or connected to, can communicate with, cooperate with, interlace, parallel with, adjacent to, bound to or bound to, have, have the property of, have to ... The functionality associated with any particular controller may be centralized or distributed, whether local or remote. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one item from the list is required. For example, "at least one of A, B, and C" includes any combination of: A; B; C; A and B; A and C; B and C; and A, B, and C.

[0020] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, programs, functions, objects, classes, instances, related data or parts thereof, which are adapted to be implemented in appropriate computer-readable program codes. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disk (DVD) or any other type of memory. "Non-transitory" computer-readable media do not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data, as well as media that can store data and the data can be overwritten later, such as rewritable optical disks or erasable storage devices.

[0021] Definitions are provided for other specific words and phrases in this patent document. Those of skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0022] Discussed below Figures 1 to 15 The various embodiments used to describe the principles of the present disclosure in this patent document are only examples and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0023] The following documents are incorporated by reference into this disclosure as if fully set forth herein: 3GPP TR 38.811 v15.2.0, "Study on NR supporting non-terrestrial networks"; 3GPP TR 38.821 v16.0.0, "NR solutions supporting non-terrestrial networks (NTN)"; 3GPP TS 38.300 v17.2.0, "5G; NR; NR and NG-RAN overall description; Stage 2"; 3GPP TS 38.331 v17.2.0, "5G; NR; Radio Resource Control (RRC); Protocol Specification|"; and 3GPP TS 38.306 v17.2.0, "5G; NR; User Equipment (UE) Radio Access Capabilities".

[0024] The following Figure 1-Figure 3 Various embodiments are described that may be implemented using orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques in a wireless communication system. Figure 1-Figure 3 The description is not meant to imply physical or architectural limitations on the implementation of the various embodiments. The various embodiments of the present disclosure may be implemented in any suitably arranged communication system.

[0025] Figure 1 An example of a wireless network according to an embodiment of the present disclosure is shown. Figure 1 The wireless network embodiment shown is for illustration only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0026] like Figure 1 As shown, the wireless network includes gNB 101 (e.g., base station BS), gNB 102, and gNB 103. gNB 101 communicates with gNB 102 and gNB 103. gNB 101 also communicates with at least one network 130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

[0027] The gNB 102 provides wireless broadband access to a network 130 for a plurality of first UEs located within a coverage area 120 of the gNB 102. The plurality of first UEs include: a UE 111 that may be located in a small business, a UE 112 that may be located in an enterprise (E), a UE 113 that may be located in a WiFi hotspot (HS), a UE 114 that may be located in a first residence (R), a UE 115 that may be located in a second residence (R), and a UE 116 that may be a mobile device (M) such as a mobile phone, a wireless laptop, a wireless PDA, etc. The gNB 103 provides wireless broadband access to the network 130 for a plurality of second UEs located within a coverage area 125 of the gNB 103. The plurality of second UEs include UE 115 and UE 116. In some embodiments, one or more of the gNBs 101-103 may communicate with each other and with the UEs 111-116 using 5G / NR, long term evolution (LTE), long term evolution advanced (LTE-A), WiMAX, WiFi, or other wireless communication technologies.

[0028] Depending on the network type, the term "base station" or "BS" may refer to any component (or set of components) configured to provide wireless access to a network, such as a transmission point (TP), a transmission-reception point (TRP), an enhanced base station (eNodeB or eNB), a 5G / NR base station (gNB), a macro cell, a femto cell, a WiFi access point (AP), or other wirelessly enabled device. A base station may provide wireless access according to one or more wireless communication protocols, such as 5G / NR 3GPP NR, Long Term Evolution (LTE), LTE Advanced (LTE-A), High Speed ​​Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc. For convenience, the terms "BS" and "TRP" may be used interchangeably in this patent document to refer to a network infrastructure component that provides wireless access to a remote terminal. In addition, depending on the network type, the term "user equipment" or "UE" may refer to any component such as a "mobile station", "user station", "remote terminal", "wireless terminal", "reception point", or "user equipment". For convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless device that accesses a base station wirelessly, whether the UE is a mobile device (such as a mobile phone or a smartphone) or a commonly considered fixed device (such as a desktop computer or a vending machine).

[0029] The dashed lines illustrate the approximate extents of coverage areas 120 and 125, which are represented as generally circular for ease of illustration and explanation. It should be expressly understood that the coverage areas associated with a gNB (e.g., coverage areas 120 and 125) may have other shapes, including irregular shapes, depending on the configuration of the gNB and variations in the radio environment associated with natural and man-made obstacles.

[0030] As discussed in more detail below, wireless network 100 may facilitate communications via one or more communication satellites 104 located in Earth orbit. Communication satellites 104 may communicate directly with base stations 102 and 103 to provide network access, for example, where base stations 102 and 103 are remotely located or require an assisted network access connection beyond or in addition to a conventional feed-forward and / or feedback connection. Various UEs (e.g., as shown by UE 116) may perform at least some direct communications and / or positioning with communication satellites 104, for example, to receive location information or coordinates.

[0031] NTN refers to a network or network segment that uses radio frequency resources located on a communication satellite (e.g., communication satellite 104) (or an unmanned aerial system platform). Given the ability to provide wide coverage and reliable services, NTN is expected to ensure ubiquitous service availability and continuity. For example, NTN can support unserved areas that are not covered by traditional terrestrial networks, underserved areas that are experiencing limited communication services, communication services for devices and passengers on mobile platforms, and for future railway / maritime / aviation communications, etc.

[0032] As described in more detail below, one or more of the user equipment 111-116 includes circuitry, programming, or a combination thereof, for utilizing a trigger for timing synchronization in the NTN. In certain embodiments, one or more of the gNBs 101-103 includes circuitry, programming, or a combination thereof, for triggering timing synchronization in the NTN.

[0033] although Figure 1 An example of a wireless network is shown, but Figure 1 Various changes may be made. For example, the wireless network may include any number of gNBs and any number of UEs in any suitable layout. In addition, gNB 101 may communicate directly with any number of UEs and provide wireless broadband access to network 130 for these UEs. Similarly, each of gNBs 102-103 may communicate directly with network 130 and provide direct wireless broadband access to network 130 for UEs. In addition, gNBs 101, 102, and / or 103 may provide access to other or additional external networks, such as an external telephone network or other type of data network.

[0034] Figure 2 An example of a gNB 102 according to an embodiment of the present disclosure is shown. Figure 2 The embodiment of gNB 102 shown is for illustration only, and Figure 1 The gNBs 101 and 103 in FIG. 1 may have the same or similar configurations. However, the gNBs may have multiple configurations, Figure 2 The scope of this disclosure is not intended to be limited to any particular implementation of a gNB.

[0035] like Figure 2 As shown, the gNB 102 includes multiple antennas 205a-205n, multiple transceivers 210a-210n, a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0036] The transceivers 210a-210n receive incident RF signals from the antennas 205a-205n, for example, signals sent by UEs in the network. The transceivers 210a-210n down-convert the incident RF signals to generate IF signals or baseband signals. The receive (RX) processing circuits in the transceivers 210a-210n and / or the controller / processor 225 process the IF signals or baseband signals to generate processed baseband signals by filtering, decoding and / or digitizing the baseband signals or IF signals. The controller / processor 225 may further process the baseband signals.

[0037] Transmit (TX) processing circuitry in the transceivers 210a-210n and / or the controller / processor 225 receives analog or digital data (e.g., voice data, web page data, email, or interactive video game data) from the controller / processor 225. The TX processing circuitry encodes, multiplexes, and / or digitizes the output baseband data to generate processed baseband or IF signals. The transceivers 210a-210n up-convert the baseband or IF signals into RF signals, which are transmitted via the antennas 205a-205n.

[0038] The controller / processor 225 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 225 may control the transceivers 210a-210n to receive UL channel signals and transmit DL channel signals in accordance with well-known principles. The controller / processor 225 may also support additional functions, such as more advanced wireless communication functions. For example, the controller / processor 225 may support beamforming or directional routing operations, in which output signals from / input signals to multiple antennas 205a-205n are assigned different weights to effectively direct the output signals in a desired direction. The controller / processor 225 may also support any of a variety of other functions in the gNB 102.

[0039] The controller / processor 225 is also capable of executing programs and other processes, such as an operating system, that reside in the memory 230. The controller / processor 225 may move data into or out of the memory 230 as required by the executed process. The controller / processor 225 is also capable of executing programs and other processes that reside in the memory 230, such as a process that triggers timing synchronization in the NTN.

[0040] The controller / processor 225 is also connected to a backhaul or network interface 235. The backhaul or network interface 235 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or network. The interface 235 can support communication via any suitable wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (such as a system supporting 5G / NR, LTE, or LTE-A), the interface 235 can allow the gNB 102 to communicate with other gNBs via a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 235 can allow the gNB 102 to communicate via a wired or wireless local area network or via a wired or wireless connection to a larger network (such as the Internet). The interface 235 includes any suitable structure that supports a wired or wireless connection, such as Ethernet or a transceiver.

[0041] Memory 230 is connected to controller / processor 225. A portion of memory 230 may include RAM, and another portion of memory 230 may include flash memory or other ROM.

[0042] although Figure 2 Only one example of a gNB 102 is shown, but Figure 2 For example, gNB 102 may include any number of Figure 2 Each component shown. In addition, Figure 2The various components in may also be combined, further subdivided, omitted, and other components may be added according to specific needs.

[0043] Figure 3 An example of a UE 116 according to an embodiment of the present disclosure is shown. Figure 3 The embodiment of UE 116 shown is for illustration only. Figure 1 The UEs 111-115 in the embodiment may have the same or similar configurations. However, the UEs may also have multiple configurations, and Figure 3 The scope of the present disclosure is not limited to any particular implementation of a UE.

[0044] like Figure 3 As shown, UE 116 includes antenna 305, transceiver 310, and microphone 320. UE 116 also includes speaker 330, processor 340, input / output (I / O) interface (IF) 345, input 350, display 355, and memory 360. Memory 360 includes operating system (OS) 361 and one or more applications 362.

[0045] The transceiver 310 receives an incident RF signal transmitted from a gNB in ​​the network 100 from the antenna 305. The transceiver 310 down-converts the incident RF signal to generate an intermediate frequency (IF) signal or a baseband signal. The IF signal or the baseband signal is processed by the RX processing circuit in the transceiver 310 and / or the processor 340 to generate a processed baseband signal by filtering, decoding and / or digitizing the baseband signal or the IF signal. The RX processing circuit sends the processed baseband signal to the speaker 330 (e.g., for voice data) or is processed by the processor 340 (e.g., for web browsing data).

[0046] The TX processing circuit in the transceiver 310 and / or the processor 340 receives analog voice data or digital voice data from the microphone 320, or other baseband data (such as web page data, email, or interactive video game data) output from the processor 340. The TX processing circuit encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband signal or an IF signal. The transceiver 310 up-converts the baseband signal or the IF signal into an RF signal and transmits the RF signal through the antenna 305.

[0047] The processor 340 may include one or more processors or other processing devices and execute the OS 361 stored in the memory 360 to control the overall operation of the UE 116. For example, the processor 340 may control the transceiver 310 to receive DL channel signals and send UL channel signals according to well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

[0048] The processor 340 is also capable of executing other processes and programs resident in the memory 360, such as processes for timing synchronization using triggers in the NTN. The processor 340 can move data into or out of the memory 360 as needed for the executed process. In some embodiments, the processor 340 is configured to execute the application 362 based on the OS 361 or in response to a signal from the gNB or operator. The processor 340 is also connected to the I / O interface 345, which provides the UE 116 with the ability to connect to other devices such as laptops and handheld computers. The I / O interface 345 is the communication path between these accessories and the processor 340.

[0049] Processor 340 is also connected to input 350, including, for example, a touch screen and a keyboard, and display 355. An operator of UE 116 can use input 350 to enter data into UE 116. Display 355 can be a liquid crystal display, a light emitting diode display, or other display capable of presenting text and / or at least limited graphics (e.g., content from a website).

[0050] The memory 360 is connected to the processor 340. A portion of the memory 360 may include a random access memory (RAM), and another portion of the memory 360 may include a flash memory or other read-only memory (ROM).

[0051] although Figure 3 An example of UE 116 is shown, but the Figure 3 Make various changes. For example, Figure 3 The various components in the embodiment may be combined, further subdivided, or omitted, and additional components may be added as required. As a specific example, processor 340 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In another example, transceiver 310 may include any number of transceivers and signal processing chains and may be connected to any number of antennas. In addition, although Figure 3 The UE 116 is shown configured as a mobile phone or smartphone, but the UE may also be configured as other types of mobile devices or fixed devices to perform operations.

[0052] Figure 4 and Figure 5An exemplary wireless transmit and receive path according to the present disclosure is shown. In the following description, the transmit path 400 may be described as being implemented in a gNB (such as gNB 102) and the receive path 500 may be described as being implemented in a UE (such as UE 116). However, it is understood that the receive path 500 may also be implemented in the gNB and the transmit path 400 may also be implemented in the UE. In some embodiments, the receive path 500 is configured to support triggering timing synchronization in the NTN as described in the embodiments of the present disclosure.

[0053] like Figure 4 As shown, the transmit path 400 includes a channel coding and modulation block 405, a serial-to-parallel conversion (S-to-P) block 410, an inverse fast Fourier transform (IFFT) block of size N 415, a parallel-to-serial conversion (P-to-S) block 420, a cyclic prefix addition block 425, and an up-converter (UC) 430. Figure 5 As shown, the receive path 500 includes a down converter (DC) 555, a cyclic prefix removal block 560, a serial to parallel conversion (S-to-P) block 565, a size-N fast Fourier transform (FFT) block 570, a parallel to serial conversion (P-to-S) block 575, and a channel decoding and demodulation block 580.

[0054] like Figure 4 As shown, channel coding and modulation block 405 receives a set of information bits, encodes (such as low density parity check (LDPC) encoding), and modulates the input bits (such as using quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a sequence of frequency domain modulation symbols.

[0055] The serial-to-parallel conversion block 410 converts (e.g., demultiplexes) the modulated serial symbols into parallel data to generate N parallel symbol streams, where N is the IFFT / FFT size used in the gNB 102 and the UE 116. The size-N IFFT block 415 is capable of performing an IFFT operation on the N parallel symbol streams to generate a time domain output signal. The parallel-to-serial block 420 converts (e.g., multiplexes) the parallel time domain output symbols from the size-N IFFT block 415 to generate a serial time domain signal. The add cyclic prefix block 425 inserts a cyclic prefix to the time domain signal. The up-converter 430 modulates (e.g., up-converts) the output of the add cyclic prefix block 425 to an RF frequency for transmission over a wireless channel. The signal may also be filtered at baseband before conversion to RF frequency.

[0056] The RF signal sent from gNB 102 reaches UE 116 through the wireless channel, and the opposite operations to those on gNB 102 are performed on UE 116.

[0057] like Figure 5 As shown, the down converter 555 down-converts the received signal to the baseband frequency, and the cyclic prefix removal block 560 removes the cyclic prefix to generate a serial time domain baseband signal. The serial to parallel conversion block 565 converts the time domain baseband signal into a parallel time domain signal. The FFT block 570 of size N performs an FFT algorithm to generate N parallel frequency domain signals. The parallel to serial conversion block 575 converts the parallel frequency domain signals into a sequence of modulated data symbols. The channel decoding and demodulation block 580 demodulates and decodes the modulated symbols to recover the original input data stream.

[0058] Each of gNBs 101-103 may implement Figure 4 The transmission path 400 shown is similar to that for transmission to UEs 111-116 in the downlink and may be implemented as follows: Figure 5 1-103. The receive path 500 shown is similar to that for receiving in the uplink from UE 111-116. Similarly, each of UE 111-116 may implement transmit path 400 for transmitting in the uplink to gNB 101-103 and may implement receive path 500 for receiving in the downlink from gNB 101-103.

[0059] Figure 4 and Figure 5 Each component in can be implemented using hardware only, or a combination of hardware and software / firmware. As a specific example, Figure 4 and Figure 5 At least some components in can be implemented in software, while other components can be implemented by configurable hardware, or a mixture of software and configurable hardware. For example, FFT block 570 and IFFT block 515 can be implemented as configurable software algorithms, wherein the value of size N can be changed according to the implementation.

[0060] In addition, although FFT and IFFT are used for description, this is for illustration only and should not be construed as limiting the scope of the present disclosure. Other types of transforms may also be used, such as discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) functions. It is understood that for DFT and IDFT functions, the value of variable N may be any integer (such as 1, 2, 3, 4, etc.), while for FFT and IFFT, the value of variable N may be any integer as a power of 2 (e.g., 1, 2, 4, 8, 16, etc.).

[0061] although Figure 4 and Figure 5 Examples of wireless transmit and receive paths are shown, but may be Figure 4 and Figure 5 For example, you can make various changes to Figure 4and Figure 5 The various components in can be combined, further subdivided, or omitted, and additional components can be added. Figure 4 and Figure 5 It is intended to be illustrative of the types of transmit and receive paths that may be used in a wireless network. Any other suitable architecture may be used to support wireless communications in a wireless network.

[0062] Figure 6 An example of NTN communication 600 according to an embodiment of the present disclosure is shown. Figure 6 The illustrated embodiment of NTN communication 600 is for illustration only.

[0063] In the 3GPP wireless standards, the New Radio Access Technology (NR) is being discussed as a 5G wireless communication technology. One of the NR features being discussed is NTN. Figure 6 As shown, NTN refers to a network or network segment that uses RF resources on a satellite (or unmanned aerial system (UAS) platform). NTN generally includes the following exemplary elements.

[0064] In one example, one or several satellite gateways may connect the NTN to the public data network.

[0065] In one example, a geosynchronous orbit (GEO) satellite (located in a circular orbit 35,786 km above the Earth's equator and following the direction of the Earth's rotation) is fed by one or several satellite gateways deployed within the satellite's target coverage area (e.g., regional coverage or even continental coverage). It can be assumed that a UE in a cell is served by only one satellite gateway.

[0066] In one example, a non-GEO satellite is continuously served by one or several satellite gateways at a time. The system ensures service and feeder link continuity between the continuously served satellite gateways with sufficient duration to allow for mobility anchoring and handover. LEO (Low Earth Orbit: orbiting the Earth at an altitude between 300 km and 1500 km) satellites are an example.

[0067] In one example, a feeder link or wireless link between a satellite gateway and a satellite (or UAS platform) is provided.

[0068] In one example, a service link or wireless link between a user device and a satellite (or UAS platform) is provided.

[0069] In one example, a satellite (or UAS platform) may implement a transparent or regenerative (with onboard processing) payload. The satellite (or UAS platform) generates beams, typically multiple beams, over a given service area defined by a field of view. The coverage of these beams is typically elliptical. The field of view of the satellite (or UAS platform) depends on the onboard antenna pattern and the minimum elevation angle.

[0070] In one example, a transparent payload is provided: RF filtering, frequency conversion and amplification. Thus, the waveform signal repeated by the payload remains unchanged.

[0071] In one example, a regenerative payload is provided: RF filtering, frequency conversion and amplification, as well as demodulation / decoding, switching and / or routing, coding / modulation. This is actually equivalent to carrying all or part of the base station functions (e.g., gNB) on the satellite (or UAS platform).

[0072] In one example, in the case of a constellation of satellites, inter-satellite links (ISLs) may be optionally provided. This may require a regenerative payload onboard the satellites. The ISLs may operate in either the RF band or the optical band.

[0073] In one example, the UE is served by a satellite (or UAS platform) within a target service area.

[0074] In 3GPP Release 17 (Rel-17), basic features of NTN were introduced, and more advanced features will be considered in Rel-18. One of the features is support for enhanced service continuity. If the radio link between the UE and the satellite fails / terminates, the service may be interrupted. This embodiment provides fast RLF detection in NTN so that the UE can re-establish the RRC connection more quickly when the radio link fails. Through this embodiment, better service continuity can be achieved.

[0075] Figure 7 An example of an NTN quasi-terrestrial fixed cell 700 according to an embodiment of the present disclosure is shown. Figure 7 The NTN quasi-terrestrial fixed cells 700 1000 are shown for illustration only.

[0076] Figure 7An example of how an NTN can provide a cell that is fixed relative to a location on the ground for a certain period of time is described. This can be achieved by an NTN platform that generates a steerable beam whose coverage is fixed on the ground. It can be assumed that Satellite 1 (SAT 1, also referred to herein as Low Earth Orbit 1 (LEO 1)) and Satellite 2 (SAT 2, also referred to herein as LEO 2) move from west to east. T1, T2, and T3 represent specific continuous time periods (e.g., T1 is between absolute time t1 and t2, T2 is between absolute time t2 and t3, and T3 is between absolute time t3 and t4).

[0077] During the T1 time period, SAT 1 provides NR services for the location of the first cell on the ground, and SAT 2 provides NR services for the location of the second cell on the ground. During the T2 time period, both SAT 1 and SAT 2 provide NR services for the location of the second cell on the ground. It is worth noting that the physical cell identifier (PCI) of the location of the second cell on the ground provided by SAT 1 and SAT 2 may be different, which means that the location of the second cell on the ground is covered by two PCIs. In this case, each PCI and the associated NR service are provided by each satellite (e.g., SAT 1 and SAT 2).

[0078] It is also worth noting that in order to avoid strong interference when two cells completely overlap, the frequency position of the synchronization signal block (SSB) including the PCI information of the cells can be different between the two cells. For example, in the T2 time period, SAT 1 serves the location of the second cell on the ground through PCI#N carried by SSB located in carrier #1, and SAT 2 serves the location of the second cell through PCI#M carried by SSB located in carrier #2. However, PCI#M of SAT 2 may disappear later because SAT 2 may serve the location of the third cell on the ground in the subsequent T3 time period. This type of NTN cell (or service link) is called a quasi-terrestrial fixed cell.

[0079] It is worth noting that the following three types of NTN cells (or service links) can be supported: (1) terrestrial fixed: provided by beams that always and continuously cover the same geographical area (e.g., the case of GSO satellites); (2) quasi-terrestrial fixed: provided by beams that cover one geographical area for a limited period of time and a different geographical area for another period of time (e.g., the case of NGSO satellites generating steerable beams); (3) terrestrial mobile: provided by beams whose coverage slides over the surface of the Earth (e.g., the case of NGSO satellites generating fixed or non-steerable beams).

[0080] Using NGSO satellites, gNB can provide quasi-terrestrial fixed cell coverage or terrestrial mobile cell coverage, while gNB operation using GSO satellites can provide terrestrial fixed cell coverage. Due to the different characteristics of GSO and NGSO, NTN can support different types of cells, namely terrestrial fixed cells, quasi-terrestrial fixed cells and terrestrial mobile cells. For a certain type of NTN payload / cell, the UE is required to support specific features or functions for wireless access.

[0081] For NTN in Release 17, TA reporting is introduced for open-loop UL synchronization and to assist NW in scheduling UEs appropriately. UEs with TA reporting capability can be configured to report their estimated TA based on UE location and satellite information in SIB during random access for RRC establishment, RRC re-establishment, RRC recovery and handover. In RRC connected state, UE reports TA in an event-triggered manner via MACCE, i.e., TA reporting is triggered when the change between the current TA and the last reported TA is equal to or greater than the configured threshold.

[0082] In Release 17, for NTN, a UE in RRC connected state can send a TA report MAC CE when a TA report event is triggered. However, when the use of HARQ process with feedback is disabled, the UE does not know whether the sending of the TA report is successful, and the interval between two successful TA reports may be long.

[0083] In addition, when the UE fails to reacquire the SIB to obtain valid satellite information including common TA and ephemeris and the validity timer (i.e., T430) expires, the UE may stop any uplink transmission and reacquire the SIB. In these cases, the gNB may not receive new TA reports for a long time, and the TA information in the gNB may be outdated, which may cause UE scheduling failure. Therefore, event-triggered TA reporting in the RRC connected state may not work well. A new TA reporting mechanism is needed.

[0084] Figure 8 FIG. 8 is a flow chart showing a UE behavior 800 for sending a TA report MAC CE with HARQ feedback according to an embodiment of the present disclosure. The UE behavior 800 may be performed by a UE (e.g., Figure 1 111-116) as shown. Figure 8 The UE behavior 800 shown is for illustration only. Figure 8 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Figure 8 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0085] To ensure that the gNB can successfully receive the new TA information in the current event-triggered report, the UE may be restricted to use only the feedback-enabled HARQ process to transmit the TA report MAC CE. Figure 8 As shown, in operation 805, if TA reporting is triggered, the UE generates a TA reporting MAC CE. The triggering of the TA report may be based on an indication from an upper layer for RRC setup, RRC reestablishment, RRC recovery, handover, periodic / aperiodic / semi-persistent TA reporting; and / or based on an indication of a DCI format in a PDCCH; and / or if the UE has not previously reported a TA value to the current serving cell, based on the configuration or reconfiguration of offsetThresholdTA by the upper layer; and / or if the change between the current TA information and the last reported TA information is equal to or greater than offsetThresholdTA (if configured).

[0086] In operation 810, the UE sends a MAC PDU including a TA report MAC CE using an uplink grant stored in a feedback enabled HARQ process. If there is no available uplink grant and / or there is no available feedback enabled HARQ process, the UE may trigger a scheduling request. In operation 815, the UE receives HARQ feedback (ACK / NACK) and triggers a retransmission or a new transmission. If a NACK is received, the UE generates a retransmission for the TA report MAC CE using the uplink grant indicated in the DCI or the configured uplink grant.

[0087] The NW may request the UE to send a TA report when necessary, for example, when the NW does not receive a new TA report within a certain period of time, and / or when the NW finds that the TA report transmission fails, and / or when the NW cannot successfully schedule the UE, and / or when the NW has downlink data to send but the UE is not synchronized. The NW may request a TA report based on the UE's ability to support TA reporting in RACH and / or the UE's ability to support TA reporting in RRC connected state.

[0088] Fig. 9 1 shows a flow chart of UE behavior 900 for NE-requested TA reporting in RACH in RRC connected state according to an embodiment of the present disclosure. UE behavior 900 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig. 9 The illustrated embodiment of UE behavior 900 is for illustration only. Fig. 9 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Fig. 9 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0089] exist Fig. 9 In one embodiment shown, in operation 905, the UE receives a TA reporting request from the gNB in ​​the RACH via a PDCCH command and / or a handover command. In one example, the UE may receive a TA reporting request indication in a DCI of a PDCCH command with a dedicated RACH preamble. The PDCCH command is sent via DCI format 1_0 scrambled with a C-RNTI CRC, which includes an SSB index, ra-PreambleIndex, and PRACH mask index, as well as a TA reporting indication using any spare bits or reusing any bits. In the case of a two-step RACH process, the PDCCH command includes an SSB index, ra-PreambleIndex, and msgA-SSB-SharedRO-MaskIndex, as well as a TA reporting indication using any spare bits in the DCI format.

[0090] In another example, the UE may receive a HO command for intra-cell handover so that the UE may perform a random access procedure to access the current serving cell. In another example, if the UE configures enabling ta-Report in the SIB, a TA report is requested in the RACH. In operation 910, the UE triggers a random access procedure using the received information. If there is no dedicated RACH preamble, the UE may trigger a CBRA procedure and send a C-RNTI MAC CE in Msg3 for contention resolution. The UE includes the TA report MAC CE in MsgA, Msg3, or Msg5.

[0091] Fig.10 FIG. 1 is a flow chart showing a UE behavior 1000 for sending a TA report MAC CE requested by a DCI or MAC CE in an RRC connected state according to an embodiment of the present disclosure. The UE behavior 1000 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig.10 The illustrated embodiment of UE behavior 1000 is for illustration only. Fig.10 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Fig.10 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0092] exist Fig.10In one embodiment shown, in operation 1005, the UE receives a TA reporting request from the gNB via PDCCH scheduling and / or MAC CE. In one example, the UE may receive a TA reporting indication in a DCI format with or without downlink allocation, wherein the indication may use any spare bit in the DCI format or reuse any bit. In another example, the TA reporting request may be indicated in a MAC CE in the PDSCH. The MAC CE may include activation of periodic, aperiodic and / or semi-persistent TA reporting. As an example, the MAC CE is identified by a subheader with an LCID or eLCID and includes a field for a one-bit indication of the TA reporting request, and / or an activation bit for periodic and / or aperiodic and / or semi-persistent TA reporting, and / or a deactivation bit for periodic and / or aperiodic and / or semi-persistent TA reporting. In operation 1010, the UE sends a TA reporting MAC CE in the PDSCH using a dynamic / configured uplink grant.

[0093] Fig.11 1 shows a flow chart of a UE behavior 1100 for sending a TA report in a UE information procedure in an RRC connected state according to an embodiment of the present disclosure. The UE behavior 1100 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig.11 The illustrated embodiment of UE behavior 1100 is for illustration only. Fig.11 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Fig.11 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0094] exist Fig.11 In another embodiment shown, the TA report may be requested by a UE information procedure as shown in the 3GPP standard specification. In operation 1105, the UE receives a UEInformationRequest message with ta-ReportRequest set to true, and then, in operation 1110, the UE may include TA information (if available) in a UEInformationResponse message only after the security activation is successful.

[0095] In the UE information procedure, an example of a TA request in a UEInformationRequest message and a TA report in a UEInformationResponse message is shown in Table 1.

[0096] Table 1

[0097] The NW may configure the UE to send TA reports periodically and / or semi-persistently and / or aperiodically according to the UE's ability to support periodic and / or semi-persistent TA reporting in the RRC connected state. In the RRC connected state, periodic and / or semi-persistent TA reporting may be a mandatory function or an optional function. If TA reporting is an optional function, the corresponding UE capability indication may be defined according to the UE, according to the frequency band, or according to the frequency band combination.

[0098] Fig.12 1200 is a flowchart showing a UE behavior 1200 for periodically or semi-persistently sending a TA report in an RRC connected state according to an embodiment of the present disclosure. The UE behavior 1200 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig.12 The illustrated embodiment of UE behavior 1200 is for illustration only. Fig.12 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Fig.12 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0099] exist Fig.12 In the illustrated embodiment, the UE receives a configuration that enables periodic TA reporting and / or enables semi-persistent TA reporting and / or configures periodicity in an RRCReconfiguration message in operation 1205. In operation 1210, the UE periodically sends a TA report in a measurement result message and / or in a TA report MAC CE according to the configuration, and / or semi-persistently sends a TA report when the TA report is activated by a MAC CE or a DCI.

[0100] In one example, periodic and / or semi-persistent TA reporting and its associated periodicity may be configured in the RRM measurement and reporting configuration of IE reportConfigNR as shown in the 3GPP standard specification. For the measId that triggers the measurement reporting process, if ta-ReportRequest-periodic in the reportConfig corresponding to the measId is set to true (true); and / or if ta-ReportRequest-semiPersistent in the reportConfig corresponding to the measId is set to true (true), and semi-persistent TA reporting is activated by MAC CE or DCI, the UE may set the measResults in the MeasurementReport message to include ta-Info (if available).

[0101] Table 2

[0102] Using NGSO satellites, gNBs can provide quasi-terrestrial fixed cell coverage or terrestrial mobile cell coverage, while gNBs using GSO satellites can provide terrestrial fixed cell coverage. Due to the different characteristics of GSO and NGSO, different types of cells can be supported in NTN, namely terrestrial fixed cells, quasi-terrestrial fixed cells, and terrestrial mobile cells. For a certain type of NTN payload / cell, the UE is expected to support specific features or functions to achieve wireless access.

[0103] In NTN in Release 17 specifications, the UE supports contention-based random access procedures and contention-free random access procedures during RRC connection establishment and handover to perform uplink UL synchronization.

[0104] In Release 18 of enhanced NTN, service link switching without PCI change is considered, which requires beam-level mobility. However, when switching to the target satellite, the UE may need to perform UL synchronization through a random access procedure. It can be specified how to trigger UL / DL synchronization and / or random access procedures for service link switching (e.g. due to satellite change).

[0105] The present disclosure specifies a solution for triggering UL / DL synchronization and / or random access procedures in NTN for service link switching.In the present disclosure, synchronization operation may refer to DL synchronization, and / or RA for UL synchronization, and / or RACH-less synchronization.

[0106] In the present disclosure, a service link handover between NTN payloads (e.g., satellite, HAPS) or cells may refer to a hard handover, wherein one NTN payload / cell provided services for a certain area before a certain time, and another NTN payload / cell provided services for the same area from that time, such that the old NTN payload / cell and the new NTN payload / cell provided services for the same area at different times and did not overlap in time, and the new cell used the same PCI and configuration as the old cell. A service link handover between NTN payloads (e.g., satellite, HAPS) or cells may also refer to a soft handover, wherein one NTN payload / cell provided services for a certain area before a certain time, and another NTN payload / cell provided services for the same area from an earlier time, such that the old NTN payload / cell and the new NTN payload / cell provided services for the same area at partially overlapping times, and the new cell used the same PCI and configuration as the old cell. In the present disclosure, the old NTN payload / cell is referred to as a source satellite / cell, and the new NTN payload / cell is referred to as a target satellite / cell.

[0107] Whenever necessary, the NW may request the UE to perform DL synchronization on the current serving cell associated with the target satellite. Whenever necessary, the NW may request the UE to perform UL synchronization on the current serving cell associated with the target satellite through random access (RA) (including CFRA, CBRA, two-step RA, four-step RA). Whenever necessary, the NW may request the UE to perform RACH-less switching on the current serving cell associated with the target satellite. The triggering and execution of DL synchronization, and / or RA for UL synchronization, and / or RACH-less switching may be described by the following embodiments.

[0108] In one embodiment, the configuration of the service link switching (e.g., parameters in SIB19, IE ntn-Config as shown in the 3GPP standard specification) is pre-configured through system information (SI) and / or RRC messages dedicated to the UE (e.g., RRCReconfiguration messages). In one example, the NW may indicate the configuration associated with the neighboring satellite / cell to be applied for the service link switching (e.g., IE ntn-config). A new field may be added to the configuration of the neighboring satellite / cell of the source cell in SIB19 to make this indication. In another example, the service link switching configuration may include one or more configuration IDs of the configuration associated with the neighboring satellite / cell to be used for the service link switching (e.g., IE ntn-config), and / or one or more PCIs to which the relevant satellite assistance information provided in the neighboring cell configuration is to be applied for the service link switching.

[0109] In one example, the configuration of the service link switching may include a dedicated RACH configuration for CFRA (e.g., 2-step RA, 4-step RA), which includes random access parameters (e.g., SSB index, ra-PreambleIndex) for the UE to perform a random access procedure for UL synchronization of the service link switching. For example, the service link switching configuration may include a RACH-less switching configuration, which includes a UL grant (e.g., a configured grant for UL transmission) and / or an offset parameter for a TA, and / or a TA group (TAG) configuration. As another example, the configuration of the service link switching may include a dedicated PDCCH configuration (e.g., time and / or frequency resources for receiving a PDCCH) for receiving a PDCCH command that triggers DL synchronization and / or a RA and / or RACH-less switching for UL synchronization.

[0110] In another example, the service link switching configuration includes switching time information. The switching time information may include a duration parameter of a switching timer, which will be started by the UE when DL synchronization for service link switching and / or RA and / or RACH-less switching for UL synchronization is started. The switching time information may include a start time and / or an end time. The start time and / or the end time may be represented by an absolute time such as UTC time. The start time indicates that the UE may start DL synchronization for service link switching and / or RA and / or RACH-less switching for UL synchronization after this time. As shown in the 3GPP standard specification, the t-service parameter of the source satellite may be included in the service link switching configuration to be reused as the start time and / or the end time. The end time indicates that the UE may start DL synchronization for service link switching and / or RA and / or RACH-less switching for UL synchronization before this time.

[0111] Fig.13 FIG. 1 is a flow chart showing a UE behavior 1300 for a RA requested by a NW in an RRC connected state according to an embodiment of the present disclosure. The UE behavior 1300 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig.13 The illustrated embodiment of UE behavior 1300 is for illustration only. Fig.13 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Fig.13 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0112] In such Fig.13In one embodiment shown, in operation 1305, the UE receives a request for DL ​​synchronization and / or RA and / or RACH-less switching for UL synchronization from the gNB via a PDCCH command. In one example, the UE may receive an indication with a dedicated RACH preamble for a service link switch in a DCI of the PDCCH command. The PDCCH command is sent via DCI format 1_0 scrambled with C-RNTICRC, and the PDCCH command includes an SSB index, ra-PreambleIndex and PRACH mask index, and a TA report request using any spare bits or reusing any bits. In the case of a 2-step RACH process, the PDCCH command includes an SSB index, ra-PreambleIndex and msgA-SSB-SharedRO-MaskIndex, and a TA report request using any spare bits in the DCI format. For SSBs broadcast by the target satellite, the SSB index and related frequency / time information of the SSB of the target cell may be configured in an RRC reconfiguration message or provided in system information so that the UE performs DL synchronization and / or RA and / or RACH-less switching for UL synchronization.

[0113] For a service link switch triggered by a PDCCH command, in one example, a one-bit indication may be included in the DCI of the PDCCH command to indicate to the target satellite the triggering of the service link switch and that the UE is about to apply a preconfigured service link switch configuration for DL ​​synchronization and / or RA and / or RACH-less switch for UL synchronization. A new bit or an existing bit in DCI format 1_0 may be defined or reused to indicate the triggering of DL synchronization for service link switch and / or RA and / or RACH-less switch for UL synchronization.

[0114] As another example, the ra-PreambleIndex and / or SSB index and / or PRACH mask index and / or RA timing configured for the service link switching may be indicated in the DCI of the PDCCH command. If such a PDCCH command is received, the UE initiates DL synchronization for the service link switching and / or RA for UL synchronization by applying the indicated ra-PreambleIndex and / or SSB index and / or PRACH mask index and / or RA timing and the preconfigured service link switching configuration.

[0115] In another example, an NTN-specific configuration ID (e.g., a logical index of a satellite configuration for a neighboring cell) and / or a PCI to which the relevant satellite assistance information provided in the neighboring cell configuration is to be applied for the service link switching may be indicated in the DCI of the PDCCH command. Upon receiving the PDCCH command including the ID / PCI for the NTN-specific configuration, the UE applies the indicated NTN-specific configuration and the pre-configured service link switching configuration for the RA for DL ​​synchronization and / or UL synchronization and / or RACH-less switching for the service link switching.

[0116] In another example, if a dedicated PDCCH configuration for receiving a PDCCH command (e.g., time and / or frequency resources for receiving a PDCCH) is configured, and if the UE receives a PDCCH command based on the dedicated PDCCH configuration, the UE initiates DL synchronization for service link switching and / or RA and / or RACH-less switching for UL synchronization by applying a pre-configured service link switching configuration.

[0117] For another embodiment of operation 1305, the UE may receive a HO / handover command for intra-cell handover and / or intra-cell service link handover via an RRC reconfiguration message, so that the UE may perform DL synchronization with a current serving cell (e.g., PCI is unchanged) associated with a target satellite and / or a random access procedure for UL synchronization and / or a RACH-less handover. The HO / handover command may include the above-mentioned service link handover configuration. In the HO / handover command, satellite assistance information for a new serving satellite (e.g., information included in IE ntn-Config as shown in the 3GPP standard specification) and / or a service link handover indication may be provided to enable the UE to perform DL synchronization and / or a random access procedure for UL synchronization and / or a RACH-less handover.

[0118] In one example, the service link switching indication may be explicitly given via a one-bit field, for example, enabling service link switching. In another example, when the HO / switching command includes a satellite ephemeris different from the current serving satellite, the UE may implicitly know the service link switching indication. In one example, a time threshold and / or duration may be configured in the intra-cell HO / switching command. The time threshold indicates an absolute time before which the UE may initiate DL synchronization and / or a random access procedure for UL synchronization and / or a RACH-less switching. Alternatively, the duration may indicate a time window within which the UE may initiate DL synchronization and / or a random access procedure for UL synchronization and / or a RACH-less switching.

[0119] In another example, the HO / handover command may include an IE reconfigurationWithSync, which includes the target cell PCI and / or configuration that is the same as the source cell PCI and / or configuration. Upon receiving the HO / handover command with an explicit or implicit serving link switch, the UE initiates DL synchronization and / or a random access procedure for UL synchronization and / or a RACH-less handover to the target satellite, while the serving cell PCI remains unchanged. If the HO / handover command includes the IE reconfigurationWithSync, the UE performs the procedures related to reconfigurationWithSync as shown in the 3GPP standard specification.

[0120] In another embodiment for operation 1305, if RA is indicated by a new field such as ra-request in system information (e.g., SIB19), the UE is requested to perform RA. If the UE obtains system information (e.g., SIB19) in which the field ra-request already exists or is enabled, the UE performs a random access procedure on the current serving cell or the indicated cell (e.g., having the same or different PCI as the current serving cell) by applying the satellite assistance information provided in the newly obtained SIB19. The service link switching indication may be included in the system information (e.g., SIB19). In one example, the service link switching indication may be explicitly given by a one-bit field. In another example, when the system information includes a satellite ephemeris different from the current serving satellite, the UE may implicitly know the service link switching indication. In one example, a time threshold and / or duration associated with the random access request indication may be configured. The time threshold indicates an absolute time before which the UE may initiate a random access procedure. Or the duration may indicate a time window within which the UE may initiate a random access procedure.

[0121] In another embodiment for operation 1305, the UE may receive a MAC CE that triggers a service link switch. The MAC CE may be identified by an LCID or an eLCID. In one example, after receiving a MAC CE that triggers a service link switch, the UE initiates DL synchronization for the service link switch and / or RA and / or RACH-less switching for UL synchronization by applying a preconfigured service link switch configuration in the RRC signaling. In another example, the MAC CE payload may include a configuration ID of a configuration (e.g., IE ntn-config) related to a neighboring satellite / cell to be applied for the service link switch, and / or a PCI to which the relevant satellite assistance information provided in the neighboring cell configuration is to be applied for the service link switch. After receiving a MAC CE that triggers a service link switch and has a payload indicating a configuration, the UE initiates DL synchronization for the service link switch and / or RA and / or RACH-less switching for UL synchronization by applying a preconfigured service link switch configuration according to the indication in the MAC CE payload. If only one configuration ID and / or PCI is configured for the target satellite / cell in the serving link handover, there may be no configuration ID and / or PCI indication in the MAC CE payload.

[0122] In operation 1310, after receiving the service link switching trigger signal (e.g., PDCCH command, RRC signaling, MAC CE) as described above, the UE initiates DL synchronization and / or RA and / or RACH-less switching for UL synchronization by applying a pre-configured service link switching configuration based on the indication in the PDCCH command and / or MAC CE and / or RRC signaling (e.g., intra-cell HO command). If the validity timer (e.g., T430) for the serving cell is running, the UE stops the timer and / or (re)starts the timer (e.g., T430) for controlling the validity of new satellite assistance information (e.g., ephemeris, common TA parameters) for UL synchronization for the serving cell. If there is no dedicated RACH preamble, the UE can trigger the CBRA process and send a C-RNTI MAC CE in msg3 for contention resolution. The UE can include a TA report MAC CE in MsgA, Msg3 or Msg5.

[0123] In one embodiment of operation 1310, if a switching timer is configured, the UE starts the switching timer after receiving the service link switching trigger signal, and based on the indication in the trigger signal, starts DL synchronization for service link switching and / or RA and / or RACH-less switching for UL synchronization by applying the pre-configured service link switching configuration. If the validity timer (e.g., T430) for the serving cell is running, the UE stops the timer and / or (re)starts the timer (e.g., T430) for controlling the validity of new satellite assistance information (e.g., ephemeris, common TA parameters) for UL synchronization for the serving cell.

[0124] In another embodiment of operation 1310, if a switching timer and a start time (e.g., t-Service) are configured for the service link switching, at the start time, the UE starts the switching timer and, based on the indication in the trigger signal, starts DL synchronization for the service link switching and / or RA and / or RACH-less switching for UL synchronization by applying the preconfigured service link switching configuration. If a validity timer (e.g., T430) for the serving cell is running, the UE stops the timer and / or (re)starts a timer (e.g., T430) for controlling the validity of new satellite assistance information (e.g., ephemeris, common TA parameters) for UL synchronization for the serving cell. In one example, the UE may use the t-Service parameter provided by the system information (e.g., SIB19) of the source cell as the start time.

[0125] In another embodiment of operation 1310, if an end time (e.g., t-Service) is configured for the service link switching, then upon receiving the service link switching trigger signal, the UE starts the switching timer by setting the configured end time to the expiration time of the timer, and based on the indication in the trigger signal, starts DL synchronization for the service link switching and / or RA and / or RACH-less switching for UL synchronization by applying the pre-configured service link switching configuration. If a validity timer (e.g., T430) for the serving cell is running, the UE stops the timer and / or (re)starts a timer (e.g., T430) for controlling the validity of new satellite assistance information (e.g., ephemeris, common TA parameters) for UL synchronization for the serving cell. In one example, the UE may use the t-Service parameter provided in the system information (e.g., SIB19) of the source cell as the end time.

[0126] If the service link switching trigger signal is received through a PDCCH command or a MAC CE, the lower layer (e.g., PHY layer, MAC layer) indicates to the upper layer (e.g., RRC layer) that the service link switching trigger has been received, and the upper layer (e.g., RRC layer) starts a switching timer.

[0127] If the handover timer is started, the UE stops the timer after successfully completing the RA or RACH-less handover to the target cell. For example, when the first UL transmission (e.g., a MAC PDU including a TA report MAC CE) is sent to the target cell, the UE considers that the RACH-less handover has been successfully completed. After successfully completing the RA or RACH-less handover to the target cell, the lower layer (e.g., the MAC layer) indicates to the upper layer (e.g., the RRC layer) that the RA or RACH-less handover to the target cell has been successfully completed, and the upper layer stops the handover timer. If the timer expires, the UE performs initial access to the target cell (e.g., 4-step CBRA, 4-step CFRA), or performs an RRC re-establishment procedure.

[0128] Whenever the configuration event is met, the UE may initiate a random access procedure for UL synchronization on the current serving cell.

[0129] Fig.14 FIG. 1 is a flow chart showing a UE behavior 1400 for an event-triggered RA in an RRC connected state according to an embodiment of the present disclosure. The UE behavior 1400 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig.14 The illustrated embodiment of UE behavior 1400 is for illustration only. Fig.14 One or more of the components shown may be implemented in dedicated circuits configured to perform the functions described, or Fig.14 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0130] exist Fig.14 In one embodiment shown, in operation 1405, the UE receives a configuration for event-triggered RA in an RRC reconfiguration message or system information from the gNB. The configuration includes a triggering event, and / or RA resource configuration for CBRA or CFRA. The network may configure event-triggered RA based on UE capabilities. The UE capability to support event-triggered RA may be defined as an optional or mandatory capability using a UE capability indication. It may be defined as a capability based on the UE capability or based on the frequency band capability.

[0131] In one example, the triggering event includes a TA offset threshold. If the offset of the UE current TA value (e.g., TA for a serving link, or TA including a serving link and a common TA) estimated based on the newly acquired satellite assistance information (i.e., ephemeris and common TA parameters) relative to the last TA value estimated based on the last acquired satellite assistance information is greater than the configured threshold, the UE initiates the RA process by using the new satellite assistance information.

[0132] In another example, the triggering event includes a TA offset threshold and a check periodicity. The UE periodically checks the TA value (e.g., a TA for a service link, or a TA including a service link and a common TA) using a configured period. If the offset of the current TA value of the UE estimated based on the current satellite position and the UE position relative to the last estimated TA value is greater than the configured threshold, the UE initiates the RA process by using the current satellite assistance information.

[0133] In an embodiment of operation 1405, the triggering event may refer to a switching window in which the UE performs random access to a new / target cell / satellite. The NW may configure a switching window, which may be indicated by a start time and a duration. For example, the t-Service parameter may be reused as the start time of the switching window so that the UE uses the t-Service parameter as the start time of the switching time. As another example, the switching start time may be indicated as an absolute time, such as UTC time. The time window configuration may be included in a UE-specific message (e.g., an RRC reconfiguration message) or system information (e.g., SIB19). The NW may configure auxiliary information (e.g., ntn-Config including ephemeris, common TA parameters, N_TA parameters for TA derivation, etc.) for the target cell / satellite to be associated with the switching window. During the switching window, the UE uses the associated auxiliary information to perform a RACH or RACH-less switching to the target cell / satellite.

[0134] For example, during the handover window, the UE applies the ephemeris and / or common TA parameters and / or N_TA parameters in the assistance information to perform TA pre-compensation and / or Doppler shift pre-compensation for UL synchronization in RACH or RACH-less handover. If the assistance information of the target cell / satellite is provided in SIB19 as a neighbor cell configuration (i.e., the target cell / satellite is one of the neighbor cells / satellites configured in SIB19), the NW can associate the PCI of the target cell with the handover window.

[0135] In operation 1410, the UE triggers a random access procedure using the received information. If there is no dedicated RACH preamble, the UE may trigger a CBRA procedure and send a C-RNTI MAC CE in msg3 for contention resolution. If TA reporting is enabled by the RRC configuration, the UE may include a TA report MAC CE in MsgA, Msg3, or Msg5.

[0136] In an embodiment of operation 1410, if a switching window is configured, after the triggering event of the switching window is satisfied, i.e., at the start time of the switching window, the UE starts a timer from the start time and sets the timer duration to the switching window duration, and then the UE performs a RACH or RACH-less switching to the target cell / satellite by applying the associated assistance information of the target cell / satellite. If the validity timer (e.g., T430) for the serving cell is running, the UE stops the timer and / or (re)starts the timer (e.g., T430) for controlling the validity of new satellite assistance information (e.g., ephemeris, common TA parameters) for UL synchronization for the serving cell.

[0137] For example, after the timer for the switching window is started, the UE restarts T430 according to the auxiliary information of the target cell / satellite. After the timer for the switching window is started, if the UE performs RACH-less switching by autonomously deriving TA, the UE restarts the time alignment timer. While the switching timer is running, the UE may suspend all DL and / or UL operations (e.g., DL / UL HARQ, scheduling request, buffer status report, etc.), except for RACH and / or RACH-less process operations for the target cell / satellite. If the RACH or RACH-less switching to the target cell / satellite is successfully completed while the timer is running, the UE stops the timer. If the timer expires, the UE declares a switching failure. After the switching fails, the UE may perform a random access procedure on the serving cell using the associated auxiliary information of the target cell / satellite, or perform beam failure recovery, or perform an RRC re-establishment procedure.

[0138] As an example, the timer of the switching window may be an RRC layer timer. When the current time is the configured start time, the timer starts. When an indication of the successful completion of the random access procedure or RACH-less procedure to the target cell / satellite is received from a lower layer (e.g., the MAC layer), the timer stops. When the timer expires, the UE performs an RRC re-establishment procedure. In another example, the timer of the switching window may be a MAC layer timer. When the current time is the configured start time, the timer is started. When the random access procedure or RACH-less procedure to the target cell / satellite is successfully completed, the timer stops. When the timer expires, the UE determines that a beam failure has occurred in the SpCell (i.e., the current serving cell) and initiates a random access procedure to the SpCell for beam failure recovery. Alternatively, a switching failure indication is sent to the RRC layer, and the UE performs an RRC re-establishment procedure.

[0139] In one embodiment, if the auxiliary information of the target cell / satellite (e.g., ntn-Config including ephemeris, common TA parameters, etc.) is different from the current configuration of the serving / source cell, the UE stops the currently running T430 and / or restarts T430 according to the auxiliary information of the target cell / satellite; otherwise (i.e., if the auxiliary information of the target cell / satellite (e.g., ntn-Config including ephemeris, common TA parameters, etc.) is the same as the current configuration of the serving / source cell), the UE maintains the currently running T430 and does not restart T430.

[0140] Fig.15 1 shows a flow chart of a UE method 1500 for timing advance reporting in NTN according to an embodiment of the present disclosure. The UE method 1500 may be performed by a UE (e.g., Figure 1 111-116) as shown. Fig.15 The illustrated embodiment of UE method 1500 is for illustration only. Fig.15 One or more of the components shown in the figure may be implemented in dedicated circuits configured to perform the functions described, or Fig.15 One or more of the components shown may be implemented by one or more processors executing instructions to perform the functions described.

[0141] like Fig.15 As shown, the method 1500 starts from step 1502. In step 1502, the UE receives first information from the BS, where the first information includes satellite assistance information for a target satellite.

[0142] In step 1504, the UE receives second information from the BS, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation.

[0143] In step 1506, the UE determines whether RACH-less synchronous operation is configured.

[0144] In step 1508, when it is determined that the RACH-less synchronous operation is not configured, the UE initiates the synchronous operation by performing a RA procedure based on the satellite assistance information and the timing information.

[0145] In one embodiment, the UE receives third information, where the third information includes RACH-less synchronization information, and the RACH-less synchronization information includes a TA parameter.

[0146] In one embodiment, the UE initiates the synchronization operation by performing a RACH-less synchronization operation using a TA parameter based on the RACH-less synchronization information. In this embodiment, the satellite assistance information includes at least one of ephemeris information, a universal TA parameter, an offset parameter, an epoch time, and a validity duration, and the first, second, and third information are received through system information or a UE-specific RRC message.

[0147] In one embodiment, the UE receives a UL grant and performs a first UL transmission using the UL grant after performing a RACH-less synchronization operation with a target satellite.

[0148] In one embodiment, the UE receives an NW trigger indication for synchronous operation. In this embodiment, the NW trigger indication is identified as: an intra-cell handover command sent via RRC signaling, an indication in a DCI included in a PDCCH; or a MAC CE including a configuration ID of a target satellite.

[0149] In one embodiment, when UL synchronization operation is started, the UE starts or restarts the validity timer for the target satellite and sends a TA report MAC CE for the target satellite in at least one of the following: Msg3 or MsgA sent in the RA procedure, the first UL transmission after the RA procedure, or the first UL transmission without RACH.

[0150] In one embodiment, the UE starts the timer upon receiving the NW trigger indication, or the UE starts the timer based on the start time and sets the timer duration of the timer to the duration.

[0151] In one embodiment, when the RA procedure is completed or the RACH-less synchronization operation is completed, the UE stops the timer, and when the timer expires, performs the RA procedure on the serving cell based on the satellite assistance information of the target satellite, or performs the RRC re-establishment procedure.

[0152] In one embodiment, the UE receives a TA report request from the BS, which is identified as: an intra-cell switching command sent via RRC signaling, or a request indication in the DCI included in the PDCCH associated with the RACH; performs RA and generates a TA report MAC CE, and sends the TA report MAC CE included in at least one of Msg3, MsgA, and the message after the RA process to the BS.

[0153] In one embodiment, the UE receives a TA report request from the BS, and the TA report request is identified as: a MAC CE including at least one of a periodic TA report request, an aperiodic TA report request, and a semi-persistent TA report request; a request indication included in an RRC message, the RRC message is a UE information request message; or an RRC reconfiguration message including a TA measurement configuration and a TA report configuration, the TA report configuration indicating at least one of a periodic TA report request, an aperiodic TA report request, and a semi-persistent TA report request; generates a TA report; and sends the TA report to the BS in the RRC message or a MAC CE included in a UL message.

[0154] The above flow charts illustrate example methods that can be implemented according to the principles of the present disclosure, and various changes can be made to the methods shown in the flow charts herein. For example, although shown as a series of steps, the individual steps in each figure can overlap, occur in parallel, occur in different orders, or occur multiple times. In another example, some steps can be omitted or replaced with other steps.

[0155] In an embodiment of the present disclosure, a user equipment (UE) includes: A transceiver configured to: receive first information from a base station (BS), the first information including satellite assistance information for a target satellite, and receive second information from the BS, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation; and a processor operably connected to the transceiver, the processor configured to: determine whether a synchronization operation without a random access channel (RACH-less) is configured, and when it is determined that the RACH-less synchronization operation is not configured, start the synchronization operation by performing a random access (RA) procedure based on the satellite assistance information and the timing information.

[0156] In an embodiment of the present disclosure, the transceiver is further configured to: receive third information, the third information includes RACH-less synchronization information, the RACH-less synchronization information includes a timing advance (TA) parameter; the processor is further configured to: start a synchronization operation based on the RACH-less synchronization information by performing a RACH-less synchronization operation using the TA parameter; the satellite assistance information includes at least one of ephemeris information, a universal TA parameter, an offset parameter, an epoch time, and a validity duration; and the first, second, and third information are received via system information or a UE-specific radio resource control (RRC) message.

[0157] In an embodiment of the present disclosure, the transceiver is further configured to: receive a UL grant; and after performing a RACH-less synchronization operation on a target satellite, perform a first UL transmission using the UL grant.

[0158] In an embodiment of the present disclosure, the transceiver is further configured to: receive a network (NW) trigger indication for synchronous operation; and the NW trigger indication is identified as: an intra-cell switching command sent via RRC signaling, an indication in downlink control information (DCI) included in a physical downlink control channel (PDCCH), or a media access control element (MAC CE) including a configuration identifier (ID) of a target satellite.

[0159] In an embodiment of the present disclosure, the processor is further configured to: start or restart a validity timer for a target satellite when starting a UL synchronization operation; and the transceiver is further configured to: send a timing advance (TA) report medium access control control element (MAC CE) for the target satellite in at least one of the following: message 3 (Msg3) or message A (MsgA) sent in a RA procedure, the first UL transmission after the RA procedure, or the first UL transmission without a RACH.

[0160] In an embodiment of the present disclosure, the processor is further configured to: start the timer when the UE receives a network (NW) trigger indication, or start the timer based on the start time; and the processor is further configured to: set the timer duration of the timer to the duration.

[0161] In an embodiment of the present disclosure, the processor is further configured to: stop the timer when the RA process is completed or the RACH-less synchronization operation is completed; and when the timer expires, perform the RA process on the serving cell based on the satellite assistance information of the target satellite, or perform the radio resource control (RRC) reconstruction process.

[0162] In an embodiment of the present disclosure, the transceiver is further configured to: receive a timing advance (TA) report request from a BS, the TA report request being identified as: an intra-cell switching command sent via RRC signaling, or a request indication in a DCI included in a PDCCH associated with a RACH; the processor is further configured to: perform RA and generate a TA report media access control element (MAC CE); and the transceiver is further configured to: send the TA report MAC CE included in at least one of message 3 (Msg3), message A (MsgA), and a message after the RA process to the BS.

[0163] In an embodiment of the present disclosure, the transceiver is further configured to: receive a timing advance (TA) report request from a BS, the TA report request being identified as: a medium access control element (MAC CE) including at least one of a periodic TA report request, an aperiodic TA report request, and a semi-persistent TA report request; a request indication included in a radio resource control (RRC) message, the RRC message being a UE information request message; or an RRC reconfiguration message including a TA measurement configuration and a TA report configuration, wherein the TA report configuration indicates at least one of a periodic TA report request, an aperiodic TA report request, and a semi-persistent TA report request. The processor is further configured to: generate a TA report; the transceiver is further configured to send the TA report to the BS in the RRC message or in the MAC CE included in the UL message.

[0164] In an embodiment of the present disclosure, a method of a user equipment (UE) includes: receiving first information from a base station (BS), the first information including satellite assistance information for a target satellite; receiving second information from the BS, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation; determining whether a synchronization operation without a random access channel (RACH-less) is configured; and when it is determined that the RACH-less synchronization operation is not configured, starting the synchronization operation by performing a random access (RA) procedure based on the satellite assistance information and the timing information.

[0165] In an embodiment of the present disclosure, it also includes: receiving third information, the third information includes RACH-less synchronization information, the RACH-less synchronization information includes a timing advance (TA) parameter; and based on the RACH-less synchronization information, starting a synchronization operation by performing a RACH-less synchronization operation using the TA parameter, wherein the satellite assistance information includes at least one of ephemeris information, a universal TA parameter, an offset parameter, an epoch time, and a validity duration, and the first, second, and third information are received through system information or a dedicated UE radio resource control (RRC) message.

[0166] In an embodiment of the present disclosure, the method further includes: receiving a UL grant; and performing a first UL transmission to a target satellite using the UL grant after a RACH-less synchronization operation.

[0167] In an embodiment of the present disclosure, it also includes: receiving a network (NW) trigger indication for synchronous operation, wherein the NW trigger indication is identified as: an intra-cell switching command sent via RRC signaling, an indication in downlink control information (DCI) included in a physical downlink control channel (PDCCH), or a media access control element (MAC CE) including a configuration identifier (ID) of a target satellite.

[0168] In an embodiment of the present disclosure, it also includes: when starting the UL synchronization operation, starting or restarting the validity timer for the target satellite; and sending a timing advance (TA) report medium access control control element (MAC CE) for the target satellite in at least one of the following: message 3 (Msg3) or message A (MsgA) sent in the RA process, the first UL transmission after the RA process, or the first UL transmission without RACH.

[0169] In an embodiment of the present disclosure, it also includes: starting a timer when the UE receives the NW trigger indication, or starting the timer based on the start time; and setting the timer duration of the timer to the duration.

[0170] In an embodiment of the present disclosure, it also includes: stopping the timer when the RA process is completed or the RACH-less synchronization operation is completed; and when the timer expires, performing the RA process on the serving cell based on the satellite assistance information for the target satellite, or performing the radio resource control (RRC) reconstruction process.

[0171] In an embodiment of the present disclosure, it also includes: receiving a timing advance (TA) report request from a BS, the TA report request being identified as: an intra-cell switching command sent via RRC signaling, or a request indication in downlink control information (DCI) included in a physical downlink control channel (PDCCH) associated with RACH; performing RA and generating a TA report media access control element (MAC CE); and sending a TA report MAC CE included in at least one of the following to the BS: message 3 (Msg3), message A (MsgA), and a message after the RA process.

[0172] In an embodiment of the present disclosure, it also includes: receiving a timing advance (TA) report request from a BS, the TA report request being identified as: a media access control control element (MAC CE) including at least one of a periodic TA report request, an aperiodic TA report request, and a semi-persistent TA report request; a request indication included in a radio resource control (RRC) message, the RRC message being a UE information request message; or an RRC reconfiguration message including a TA measurement configuration and a TA report configuration, wherein the TA report configuration indicates at least one of a periodic TA report request, an aperiodic TA report request, and a semi-persistent TA report request; generating a TA report; and sending the TA report to the BS in the RRC message or in a MAC CE included in a UL message.

[0173] In an embodiment of the present disclosure, a base station (BS) includes: a processor; and a transceiver operably connected to the processor, the transceiver being configured to: send first information to a user equipment (UE), the first information including satellite assistance information for a target satellite, and send second information to the UE, the second information including timing information, wherein the timing information includes at least one of a start time and a duration for a synchronization operation; send third information to the UE, the third information indicating whether a synchronization operation without a random access channel (RACH-less) is configured, wherein when it is indicated that the RACH-less synchronization operation is not configured, the synchronization operation is started based on the satellite assistance information and the timing information.

[0174] In an embodiment of the present disclosure, the third information includes RACH-less synchronization information, the RACH-less synchronization information includes a timing advance (TA) parameter; and the transceiver is further configured to: send an UL authorization; send a network (NW) trigger indication for synchronous operation, the NW trigger indication being identified as: an intra-cell handover command sent via RRC signaling, an indication in downlink control information (DCI) included in a physical downlink control channel (PDCCH), or a media access control control element (MAC CE) including a configuration identifier (ID) of a target satellite; send a TA report request to a UE; and receive a TA report MAC CE for the target satellite from the UE.

[0175] Fig.16 The structure of a UE according to an embodiment of the present disclosure is shown.

[0176] like Fig.16As shown, the UE according to the embodiment may include a transceiver 1610, a memory 1620, and a processor 1630. The transceiver 1610, the memory 1620, and the processor 1630 of the UE may operate according to the communication method of the above-mentioned UE. However, the components of the UE are not limited thereto. For example, the UE may include more or fewer components than those described above. In addition, the processor 1630, the transceiver 1610, and the memory 1620 may be implemented as a single chip. In addition, the processor 1630 may include at least one processor. In addition, Fig.16 The UEs in Figure 1 Corresponding to UE 111, 112, 113, 114, 115, 116 in the.

[0177] The transceiver 1610 generally refers to a UE receiver and a UE transmitter, and may send / receive signals to / from a base station or a network entity. The signals sent or received to or from a base station or a network entity may include control information and data. The transceiver 1610 may include an RF transmitter for up-converting and amplifying the frequency of a transmitted signal, and an RF receiver for low-noise amplification and down-conversion of the frequency of a received signal. However, this is only an example of the transceiver 1610, and the components of the transceiver 1610 are not limited to the RF transmitter and the RF receiver.

[0178] In addition, the transceiver 1610 may receive a signal from the processor 1630 and output a signal to the processor 1730 through a wireless channel, and transmit a signal output by the processor 1630 through a wireless channel.

[0179] The memory 1620 may store programs and data required for the UE to run. In addition, the memory 1620 may store control information or data included in the signal obtained by the UE. The memory 1620 may be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0180] The processor 1630 may control a series of processes so that the UE operates as described above. For example, the transceiver 1610 may receive a data signal including a control signal sent by a base station or a network entity, and the processor 1630 may determine a result of receiving the control signal and the data signal sent by the base station or the network entity.

[0181] Fig.17 The structure of a base station according to an embodiment of the present disclosure is shown.

[0182] like Fig.17As shown, the base station according to the embodiment may include a transceiver 1710, a memory 1720 and a processor 1730. The transceiver 1710, the memory 1720 and the processor 1730 of the base station may operate according to the communication method of the above-mentioned base station. However, the components of the base station are not limited thereto. For example, the base station may include more or fewer components than those described above. In addition, the processor 1730, the transceiver 1710 and the memory 1720 may be implemented as a single chip. In addition, the processor 1730 may include at least one processor. In addition, Fig.17 The base stations in Figure 1 Corresponding to the base stations (eg, BS 101, 102, 103) in.

[0183] The transceiver 1710 generally refers to a base station receiver and a base station transmitter, and may send / receive signals to / from a terminal (UE) or a network entity. The signals sent or received to or from the terminal or the network entity may include control information and data. The transceiver 1710 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplification and down-conversion of the frequency of the received signal. However, this is merely an example of the transceiver 1710, and the components of the transceiver 1710 are not limited to the RF transmitter and the RF receiver.

[0184] In addition, the transceiver 1710 may receive a signal from the processor 1730 and output a signal to the processor 1730 through a wireless channel, and transmit the signal output by the processor 1730 through a wireless channel.

[0185] The memory 1720 may store programs and data required for the base station to operate. In addition, the memory 1720 may store control information or data included in the signal obtained by the base station. The memory 1720 may be a storage medium such as ROM, RAM, hard disk, CD-ROM and DVD, or a combination of storage media.

[0186] The processor 1730 may control a series of processes so that the base station operates as described above. For example, the transceiver 1710 may receive a data signal including a control signal transmitted by a terminal, and the processor 1730 may determine a result of receiving the control signal and the data signal transmitted by the terminal.

[0187] Although the present disclosure has been described in conjunction with exemplary embodiments, various changes and modifications may be suggested by those skilled in the art. The present disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims. Any description in this application should not be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined by the claims.

Claims

1. A user equipment UE, comprising: Transceiver, configured as: receiving first information from a base station BS, the first information comprising satellite assistance information for a target satellite, and receiving second information from the BS, the second information comprising timing information, wherein the timing information comprises at least one of a start time and a duration for a synchronization operation; and A processor is operably connected to the transceiver, wherein the processor is configured to: Determine whether synchronous operation without a random access channel (RACH-less) is configured, and In case it is determined that the RACH-less synchronous operation is not configured, the synchronous operation is initiated by performing a random access RA procedure based on the satellite assistance information and the timing information.

2. The UE according to claim 1, wherein: The transceiver is further configured to: receive third information, the third information comprising RACH-less synchronization information, the RACH-less synchronization information comprising a timing advance TA parameter; The processor is further configured to: initiate the synchronization operation by performing the RACH-less synchronization operation using the TA parameter based on the RACH-less synchronization information; The satellite assistance information includes at least one of ephemeris information, common TA parameters, offset parameters, epoch time, and validity duration; as well as The first information, the second information, and the third information are received through system information or a UE-specific radio resource control RRC message.

3. The UE according to claim 1, wherein: The transceiver is also configured as: Receive UL authorization; and After the RACH-less synchronization operation, a first UL transmission is performed to the target satellite using the UL grant.

4. The UE according to claim 1, wherein: The transceiver is further configured to: receive a network NW trigger indication for the synchronization operation; and The NW trigger indication is identified as: Intra-cell handover command sent via RRC signaling, An indication in the downlink control information DCI included in the physical downlink control channel PDCCH, or A medium access control element MAC CE including the configuration identification ID of the target satellite.

5. The UE according to claim 1, wherein: The processor is further configured to: start or restart a validity timer for the target satellite when starting a UL synchronization operation; and The transceiver is further configured to: send a timing advance TA report medium access control element MAC CE for the target satellite in at least one of the following: Message 3 Msg3 or message A MsgA sent in the RA process, the first UL transmission after the RA procedure, or The first UL transmission does not require RACH.

6. The UE according to claim 1, wherein: The processor is further configured to: When the UE receives a network NW trigger indication, a timer is started, or Based on the start time, starting a timer; and The processor is further configured to set a timer duration of the timer to the duration.

7. The UE according to claim 1, wherein: The processor is further configured to: When the RA procedure is completed or the RACH-less synchronization operation is completed, stopping the timer; and When the timer expires, the RA procedure is performed on the serving cell based on the satellite assistance information of the target satellite, or a radio resource control RRC re-establishment procedure is performed.

8. The UE according to claim 1, wherein: The transceiver is further configured to: receive a timing advance TA report request from the BS, the timing advance TA report request being identified as: An intra-cell handover command sent via RRC signaling; or A request indication in downlink control information DCI included in a physical downlink control channel PDCCH associated with RACH; The processor is further configured to: execute the RA and generate a TA report medium access control element MAC CE; and The transceiver is further configured to: send the TA report MAC CE to the BS, wherein the TA report MAC CE is included in at least one of message 3 Msg3, message A MsgA, and a message after the RA procedure.

9. The UE according to claim 1, wherein: The transceiver is further configured to: receive a timing advance TA report request from the BS, the timing advance TA report request being identified as: a medium access control element MAC CE including at least one of a periodic TA report request, an aperiodic TA report request and a semi-persistent TA report request; A request indication included in a radio resource control (RRC) message, the RRC message being a UE information request message, or an RRC reconfiguration message including a TA measurement configuration and a TA report configuration, wherein the TA report configuration indicates at least one of the periodic TA report request, the aperiodic TA report request, and the semi-persistent TA report request; The processor is further configured to: generate a TA report; as well as The transceiver is further configured to send the TA report to the BS in an RRC message or in a MAC CE included in a UL message.

10. A method of a user equipment UE, the method comprising: receiving first information from a base station BS, wherein the first information includes satellite assistance information for a target satellite; receiving second information from the BS, the second information comprising timing information, wherein the timing information comprises at least one of a start time and a duration for a synchronization operation; determining whether synchronous operation without a random access channel RACH-less is configured; and When it is determined that the RACH-less synchronous operation is not configured, the synchronous operation is initiated by performing a random access RA procedure based on the satellite assistance information and the timing information.

11. The method according to claim 10, further comprising: receiving third information, where the third information includes RACH-less synchronization information, where the RACH-less synchronization information includes a timing advance TA parameter; as well as initiating the synchronization operation by performing the RACH-less synchronization operation using the TA parameters based on the RACH-less synchronization information, in: The satellite assistance information includes at least one of ephemeris information, common TA parameters, offset parameters, epoch time, and validity duration, and The first information, the second information, and the third information are received through system information or a UE-specific radio resource control RRC message.

12. The method according to claim 10, further comprising: Receive UL authorization; as well as After the RACH-less synchronization operation, a first UL transmission is performed to the target satellite using the UL grant.

13. The method according to claim 10, further comprising: receiving a network NW trigger indication for the synchronization operation, The NW trigger indication is identified as: Intra-cell handover command sent via RRC signaling; An indication in the downlink control information DCI included in the physical downlink control channel PDCCH; or A medium access control element MAC CE including the configuration identification ID of the target satellite.

14. A base station BS, comprising: processor; as well as A transceiver is operably connected to the processor, and the transceiver is configured to: sending first information to a user equipment UE, wherein the first information includes satellite assistance information for a target satellite, and sending second information to the UE, the second information comprising timing information, wherein the timing information comprises at least one of a start time and a duration for a synchronization operation, sending third information to the UE, the third information indicating whether a synchronous operation without a random access channel RACH-less is configured, in: When it is indicated that RACH-less synchronous operation is not configured, the synchronous operation is initiated based on the satellite assistance information and the timing information.

15. A method of a base station, the method comprising: sending first information to a user equipment UE, wherein the first information includes satellite assistance information for a target satellite, and sending second information to the UE, the second information comprising timing information, wherein the timing information comprises at least one of a start time and a duration for a synchronization operation, sending third information to the UE, the third information indicating whether a synchronous operation without a random access channel RACH-less is configured, in: When it is indicated that the RACH-less synchronous operation is not configured, the synchronous operation is initiated based on the satellite assistance information and the timing information.

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