Method and apparatus for UE initiated early timing advance acquisition

Abstract

The present disclosure relates to a 5G or 6G communication system supporting a higher data transmission rate. Methods and apparatus are provided for user equipment (UE) initiated early TA acquisition. In one embodiment, a UE includes a transceiver configured to receive an early timing advance (TA) configuration of an early timing advance (RA) random access (RA) resource comprising a candidate cell for conditional layer 1 / layer 2 triggered mobility (CLTM), transmit a physical random access channel (PRACH) preamble to the candidate cell on the early TA RA resource, and receive a message comprising a current TA of the candidate cell. The UE also includes a processor operably coupled with the transceiver, the processor configured to apply the current TA to the candidate cell, and start a time alignment timer (TAT) for the candidate cell.

Description

Technical Field

[0001] This disclosure generally relates to wireless networks. More specifically, this disclosure relates to early timing advance acquisition initiated by the UE. Background Technology

[0002] Fifth-generation (5G) mobile communication technology defines wide frequency bands, enabling high transmission rates and new services. This can be achieved not only in sub-6 GHz bands such as 3.5 GHz, but also in "above 6 GHz" bands known as millimeter waves (mmWave), including 28 GHz and 39 GHz. Furthermore, to achieve transmission rates 50 times faster than 5G and ultra-low latency by 1 / 10, sixth-generation (6G) mobile communication technology (referred to as "super 5G systems") is being considered in terahertz (THz) bands (e.g., the 95 GHz to 3 THz band).

[0003] In the early stages of 5G mobile communication technology development, to support enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC) services and meet performance requirements, standardization work has been ongoing on beamforming and massive multiple-input multiple-output (MIMO) technologies to mitigate radio wave path loss and increase radio wave transmission distance in millimeter waves. Furthermore, support for parameter sets (e.g., supporting multiple subcarrier spacings) for efficient utilization of millimeter wave resources and dynamic operation of time slot formats, initial access technologies to support multi-beam transmission and broadband, the definition and operation of the bandwidth portion (BWP), novel channel coding schemes such as low-density parity-check (LDPC) codes for large-scale data transmission and polar codes for highly reliable transmission of control information, layer 2 (L2) preprocessing, and network slicing technologies for providing dedicated networks for specific services have also been used to support these services and meet performance requirements.

[0004] Currently, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology, considering the services it will support. Physical layer standardization work is also underway for the following technologies: Vehicle-to-Everything (V2X) technology, which uses vehicle-transmitted location and status information to assist autonomous vehicles in making driving decisions and improve user convenience; New Radio Unlicensed (NR-U) technology, designed to meet various regulatory requirements for system operation in unlicensed frequency bands; New Radio (NR) User Equipment (UE) energy-saving technologies; UE-satellite direct communication technology (Non-Terrestrial Network (NTN) technology) to provide coverage for areas unable to communicate with terrestrial networks; and positioning technologies.

[0005] Furthermore, in terms of air interface architecture / protocols, standardization efforts are ongoing for the following technologies: Industrial Internet of Things (IIoT) supporting new services through interconnection and integration with other industries; Integrated Access Backhaul (IAB) providing nodes for network service area extension by supporting wireless backhaul and access links in an integrated manner; mobility enhancements including conditional handover and Dual Active Protocol Stack (DAPS) handover; and two-step random access (e.g., NR's Two-Step Random Access Channel (RACH)) to simplify random access procedures. In terms of system architecture / services, standardization efforts are also ongoing for 5G baseline architectures (e.g., service-based architectures or service-based interfaces) that combine Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, as well as Mobile Edge Computing (MEC) providing services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, various connected devices will be integrated into the communication network. Enhanced functionality and performance of 5G mobile communication systems, as well as integrated operation of connected devices, are expected to become essential. Therefore, new research in the following related areas is on the agenda: Extended Reality (XR) for efficient support of Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR); Utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication to improve 5G performance and reduce complexity.

[0007] Furthermore, this development of 5G mobile communication systems will lay the foundation for the development of the following technologies: novel waveforms for providing coverage in the terahertz band of 6G mobile communication technology; multi-antenna transmission technologies such as full-dimensional multiple-input multiple-output (FD-MIMO), array antennas, and massive MIMO; metamaterial-based lenses and antennas for improving terahertz band signal coverage; high-dimensional spatial multiplexing technologies utilizing orbital angular momentum (OAM); reconfigurable smart surfaces (RIS) technology; full-duplex technology for improving the frequency efficiency of 6G mobile communication technology and enhancing system networks; AI-based communication technologies that leverage satellites and AI from the design phase to achieve system optimization and incorporate end-to-end AI support; and next-generation distributed computing technologies that utilize ultra-high-performance communication and computing resources to provide services with complexity exceeding the operational limits of the UE.

[0008] With the increasing prevalence of smartphones and other mobile data devices (such as tablets, laptops, netbooks, e-readers, and machine-type devices) among consumers and businesses, the demand for wireless data services is growing rapidly. To meet this rapid growth and support new applications and deployments, improving the efficiency and coverage of wireless interfaces is crucial.

[0009] To meet the growing demand for wireless data services since the deployment of 4G communication systems and to support various vertical applications, 5G communication systems have been developed and are being deployed. Key technologies for 5G / NR mobile communications include massive MIMO (covering from traditional cellular bands to high-frequency bands) to provide beamforming gain and support capacity enhancement; new waveforms (such as new radio access technologies (RAT)) to flexibly adapt to various services / applications with different requirements; and new multiple access schemes to support massive connectivity. Summary of the Invention

[0010] [Technical Issues]

[0011] This disclosure provides apparatus and methods for early timing advance acquisition initiated by a UE.

[0012] [Technical Solution]

[0013] In one embodiment, a method performed by a terminal is provided. The method includes: receiving configuration information from a base station of a serving cell for configuring random access resources for early timing advance (TA) acquisition on a candidate cell; performing an early TA acquisition procedure for the candidate cell; receiving from the base station a Media Access Control (MAC) control element (CE) associated with a cell handover for L1 / L2 triggered mobility (LTM) and, based on the MAC CE associated with the cell handover for L1 / L2 triggered LTM, performing a cell handover to the target cell. The configuration information for the early TA acquisition includes information about random access channel resources, uplink configuration for a carrier, and information about the bandwidth portion (BWP).

[0014] In another embodiment, a method performed by a base station is provided. The method includes: sending configuration information to a terminal for configuring random access resources acquired early timing (TA) on a candidate cell; and sending a Media Access Control (MAC) control element (CE) associated with a cell handover for L1 / L2 triggered mobility (LTM) based on an early TA acquisition procedure performed for the candidate cell. The cell handover to a target cell is performed based on the MAC CE associated with the cell handover for L1 / L2 triggered LTM, and the configuration information for the early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

[0015] In another embodiment, a terminal is provided. The terminal includes a transceiver and at least one processor, the at least one processor being configured to: receive configuration information from a base station of a serving cell for configuring random access resources for early timing advance (TA) acquisition on a candidate cell; execute an early TA acquisition procedure for the candidate cell; receive from the base station a Media Access Control (MAC) control element (CE) associated with cell handover for L1 / L2 triggered mobility (LTM); and, based on the MAC CE associated with the cell handover for L1 / L2 triggered LTM, execute a cell handover to the target cell. The configuration information for early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

[0016] In another embodiment, a base station is provided. The base station includes a transceiver and at least one processor, the at least one processor being configured to: send configuration information to a terminal for configuring random access resources acquired early timing (TA) on a candidate cell, and, based on an early TA acquisition procedure performed for the candidate cell, send to the terminal a Media Access Control (MAC) control element (CE) associated with a cell handover for L1 / L2 triggered mobility (LTM). The cell handover to a target cell is performed based on the MAC CE associated with the cell handover for L1 / L2 triggered LTM, wherein the configuration information for early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

[0017] In another embodiment, a user equipment (UE) is provided. The UE includes a transceiver configured to: receive an early TA configuration containing early TA random access (RA) resources for candidate cells with condition L1 / L2 triggered mobility (CLTM); transmit a physical random access channel (PRACH) preamble to the candidate cells on the early TA RA resources; and receive a message containing a current TA for the candidate cells. The UE also includes a processor operatively coupled to the transceiver. The processor is configured to: apply the current TA to the candidate cells and start a time alignment timer (TAT) for the candidate cells.

[0018] In another embodiment, a base station (BS) is provided. The BS includes a processor and a transceiver operatively coupled to the processor, the transceiver being configured to: transmit an early TA configuration containing early TA RA resources for candidate cells for mobility triggered by condition L1 / L2; receive a PRACH preamble for the candidate cells on the early TA RA resources; and transmit a message containing a current TA for the candidate cells.

[0019] In yet another embodiment, a method for operating a UE is provided. The method includes: receiving an early TA configuration containing early TA RA resources for a candidate cell for CLTM; sending a PRACH preamble to the candidate cell on the early TA RA resources; receiving a message containing a current TA for the candidate cell; applying the current TA to the candidate cell; and initiating a TAT for the candidate cell.

[0020] Other technical features will be clearly understood by those skilled in the art from the following figures, description and claims.

[0021] [Beneficial Effects]

[0022] According to various embodiments of this disclosure, a method for early timing advance acquisition initiated by a UE is provided. Attached Figure Description

[0023] To gain a more complete understanding of this disclosure and its advantages, the following description is provided in conjunction with the accompanying drawings, wherein: Figure 1 An exemplary wireless network according to an embodiment of this disclosure is shown; Figure 2A and Figure 2B An exemplary wireless transmission and reception path according to an embodiment of this disclosure is shown; Figure 3A An exemplary UE according to an embodiment of this disclosure is shown; Figure 3B An exemplary gNB according to an embodiment of this disclosure is shown; Figure 4 Exemplary condition switching operations according to embodiments of this disclosure are shown; Figure 5 An exemplary UE process for early TA acquisition for a non-serving cell, initiated by a UE according to an embodiment of this disclosure, is shown; Figure 6 An exemplary UE procedure for a four-step CBRA for early TA acquisition with the participation of a serving cell is shown according to an embodiment of this disclosure; Figure 7 An exemplary early TA contention resolution identifier MAC CE according to an embodiment of this disclosure is shown; Figure 8 An exemplary UE procedure for a four-step CBRA with serving cell involvement, according to an embodiment of this disclosure, is shown. Figure 9 An exemplary UE procedure for a two-step CBRA (Cell-Based Early TA Acquisition) with no serving cell participation, according to embodiments of this disclosure, is shown; and Figure 10 An exemplary method for early TA acquisition initiated by a UE according to an embodiment of this disclosure is shown. Detailed Implementation

[0024] Before proceeding with the following detailed description, it may be helpful to define certain words and phrases in this patent document. The term “coupled” and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether these elements are physically in contact with each other. The terms “transmit,” “receive,” and “communicate,” and their derivatives cover both direct and indirect communication. The terms “including” and “contains,” and their derivatives refer to, but are not limited to, including. The term “or” is inclusive, meaning and / or. The phrase “associated with” and its derivatives refer to including, being contained within, interconnected with, containing, being included in, connected to or connected with, coupled to or coupled with, able to communicate with, cooperate with, interleaved, juxtaposed, proximate, bound to or bound to, having, possessing the attributes of, having a relationship with, etc. The term “controller” refers to any device, system, or part thereof that controls at least one operation. Such a controller may be implemented by hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller may be centralized or distributed, local or remote. When used with a list of items, the phrase "at least one" means that different combinations of the listed items may be used, and only one item is required in the list. For example, "at least one of A, B, and C" includes the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0025] Furthermore, the various functions described below may be implemented or supported by one or more computer programs, each computer program being formed by 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, associated data, or portions thereof suitable for implementation in appropriate computer-readable program code. 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 computer-accessible medium, such as read-only memory (ROM), random access memory (RAM), hard disk drive, optical disc (CD), digital video disc (DVD), or any other type of storage. "Non-transitory" computer-readable media does not include wired, wireless, optical, or other communication links that transmit transient electrical or other signals. Non-transitory computer-readable media includes media that permanently store data and media that store and subsequently rewrite data, such as rewritable optical discs or erasable storage devices.

[0026] This patent document also provides definitions for certain other words and phrases. Those skilled in the art will understand that, in many cases (if not most), such definitions apply to the prior and future use of these words and phrases.

[0027] The following discussion Figures 1 to 10 The various embodiments used to describe the principles of this disclosure are for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Those skilled in the art will understand that the principles of this disclosure can be implemented in any properly configured wireless communication system.

[0028] To meet the growing demand for wireless data services since the deployment of 4G communication systems and to support various vertical applications, 5G / NR communication systems have been developed and are being deployed. 5G / NR communication systems are expected to be implemented at higher frequency bands (millimeter waves) (e.g., 28 GHz or 60 GHz) to achieve higher data rates, or at lower frequency bands (e.g., 6 GHz) to support robust coverage and mobility. To reduce radio wave propagation loss and increase transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are being researched in 5G / NR communication systems.

[0029] In addition, in 5G / NR communication systems, the development and improvement of system networks based on technologies such as advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, cooperative multipoint (CoMP), and receiver interference cancellation are also underway.

[0030] The discussion of 5G systems and their associated frequency bands is for reference only, as some embodiments of this disclosure can be implemented in 5G systems. However, this disclosure is not limited to 5G systems or their associated frequency bands, and embodiments of this disclosure can be used in any frequency band. For example, aspects of this disclosure can also be applied to the deployment of 5G communication systems, 6G, and even later versions, which may use terahertz (THz) frequency bands.

[0031] the following Figures 1 to 3B Various embodiments implemented in wireless communication systems are described, as well as embodiments using orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication technologies. Figures 1 to 3B The description is not intended to imply any physical or architectural limitation on the implementation of the different embodiments. The different embodiments of this disclosure can be implemented in any suitably configured communication system.

[0032] Figure 1 An exemplary wireless network 100 according to an embodiment of this disclosure is shown. Figure 1 The wireless network embodiment shown is for illustrative purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of this disclosure.

[0033] like Figure 1 As shown, the wireless network includes gNB 101 (e.g., a 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.

[0034] gNB 102 provides wireless broadband access to network 130 to multiple first user equipments (UEs) within its coverage area 120. These first user equipments include UE 111 located in a small business, UE 112 located in a business, UE 113 acting as a WiFi hotspot, UE 114 located in a first residence, UE 115 located in a second residence, and mobile devices (such as cellular phones, wireless laptops, wireless PDAs, etc.) UE 116. gNB 103 provides wireless broadband access to network 130 to multiple second user equipments within its coverage area 125. These second user equipments include UE 115 and UE 116. In some embodiments, one or more of gNBs 101-103 may communicate with UEs 111-116 using 5G / NR, LTE, LTE-A, WiMAX, WiFi, or other wireless communication technologies.

[0035] Depending on the network type, the term "base station" or "BS" can refer to any component (or set of components) configured to provide wireless access to the network, such as a transport point (TP), a transport receiver point (TRP), an enhanced base station (eNodeB or eNB), a 5G / NR base station (gNB), a macro cell, a femtocell, a WiFi access point (AP), or other wireless enabling devices. The base station may provide wireless access according to one or more wireless communication protocols, such as 3G Partnership 5G / NR, Long Term Evolution (LTE), LTE-A Advanced (LTE-A), High Speed ​​Packet Access (HSPA), WiFi 802.11a / b / g / n / ac, etc. For convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. Furthermore, depending on the network type, the term "user equipment" or "UE" can refer to any component, such as a "mobile station," "user station," "remote terminal," "wireless terminal," "receiving point," or "user equipment." For convenience, the terms “user equipment” and “UE” in this patent document are used to refer to a remote wireless device that provides wireless access to a BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or a fixed device as commonly considered (such as a desktop computer or vending machine).

[0036] The dashed lines indicate the approximate extent of coverage areas 120 and 125, which are shown as roughly circular for ease of illustration and explanation. It should be clearly understood that coverage areas associated with the gNB (such as 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.

[0037] As described in more detail below, one or more of UEs 111-116 include circuitry, programming, or a combination thereof for UE-initiated early timing advance fetching. In some embodiments, one or more of gNBs 101-103 include circuitry, programming, or a combination thereof for supporting UE-initiated early timing advance fetching in a wireless communication system.

[0038] although Figure 1 An example of a wireless network is shown, but it is not applicable to... Figure 1Various modifications can be made. For example, the wireless network can include any number of gNBs and any number of UEs, and can be arranged in any suitable manner. Furthermore, gNB 101 can communicate directly with any number of UEs and provide these UEs with wireless broadband access to network 130. Similarly, each gNB 102-103 can communicate directly with network 130 and provide UEs with direct wireless broadband access to network 130. Additionally, gNBs 101, 102, and / or 103 can provide access to other or additional external networks, such as external telephone networks or other types of data networks.

[0039] Figure 2A and Figure 2B Exemplary wireless transmit and receive paths according to embodiments of this disclosure are illustrated. In the following description, transmit path 200 may be described as being implemented in a gNB (such as gNB 102), and receive path 250 may be described as being implemented in a UE (such as UE 116). However, it should be understood that receive path 250 may be implemented in the gNB, and transmit path 200 may be implemented in the UE. In some embodiments, transmit path 200 and / or receive path 250 are configured to implement and / or support UE-initiated early timing advance acquisition as described in embodiments of this disclosure.

[0040] The transmit path 200 includes a channel coding and modulation block 205, a serial-to-parallel (S-to-P) conversion block 210, an N-size inverse fast Fourier transform (IFFT) block 215, a parallel-to-serial (P-to-S) conversion block 220, a cyclic prefix addition block 225, and an up-converter (UC) 230. The receive path 250 includes a down-converter (DC) 255, a cyclic prefix removal block 260, a serial-to-parallel (S-to-P) conversion block 265, an N-size fast Fourier transform (FFT) block 270, a parallel-to-serial (P-to-S) conversion block 275, and a channel decoding and demodulation block 280.

[0041] In transmission path 200, channel coding and modulation block 205 receives a set of information bits, applies coding (such as low-density parity-check (LDPC) coding), and modulates the input bits (such as quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a frequency-domain modulated symbol sequence. Serial-to-parallel conversion block 210 converts (e.g., demultiplexes) the serial modulated symbols into parallel data to generate N parallel symbol streams, where N is the IFFT / FFT size used in gNB 102 and UE 116. IFFT block 215 of size N performs an IFFT operation on the N parallel symbol streams to generate a time-domain output signal. Parallel-to-serial conversion block 220 converts (e.g., multiplexes) the parallel time-domain output symbols from IFFT block 215 of size N into a serial time-domain signal. Cyclic prefix addition block 225 inserts a cyclic prefix into the time-domain signal. Upconverter 230 modulates (e.g., upconverts) the output of cyclic prefix addition block 225 to the RF frequency for transmission over the wireless channel. The signal can also be filtered in the baseband before switching to the RF frequency.

[0042] The RF signal transmitted from gNB 102 reaches UE 116 after passing through the wireless channel, and the UE 116 performs the opposite operation to that in gNB 102. Downconverter 255 downconverts the received signal to the baseband frequency, and cyclic prefix removal block 260 removes the cyclic prefix to generate a serial time-domain baseband signal. Serial-to-parallel conversion block 265 converts the time-domain baseband signal into a parallel time-domain signal. An N-sized FFT block 270 performs an FFT algorithm to generate N parallel frequency-domain signals. Parallel-to-serial conversion block 275 converts the parallel frequency-domain signals into a modulated data symbol sequence. Channel decoding and demodulation block 280 demodulates and decodes the modulated symbols to recover the original input data stream.

[0043] Each of gNBs 101-103 can implement a transmission path 200 similar to that used for transmission to UEs 111-116 in the downlink, and a reception path 250 similar to that used for reception from UEs 111-116 in the uplink. Similarly, each of UEs 111-116 can implement a transmission path 200 for transmission to gNBs 101-103 in the uplink, and a reception path 250 for reception from gNBs 101-103 in the downlink.

[0044] Figure 2A and Figure 2B Each component in the system can be implemented using only hardware or a combination of hardware and software / firmware. As a specific example, Figure 2A and Figure 2BAt least some components can be implemented in software, while others can be implemented in configurable hardware or a hybrid of software and configurable hardware. For example, FFT block 270 and IFFT block 215 can be implemented as configurable software algorithms, where the value of size N can be modified depending on the implementation.

[0045] Furthermore, although the description uses FFT and IFFT, this is for illustrative purposes only and should not be construed as limiting the scope of this disclosure. Other types of transforms, such as the Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions, may be used. It should be understood that for DFT and IDFT functions, the variable N can be any integer value (e.g., 1, 2, 3, 4, etc.), while for FFT and IFFT functions, the variable N can be any integer value that is a power of 2 (e.g., 1, 2, 4, 8, 16, etc.).

[0046] although Figure 2A and Figure 2B An example of a wireless transmit and receive path is shown, but it is possible to modify it further. Figure 2A and Figure 2B Make various changes. For example, Figure 2A and Figure 2B The various components can be combined, further subdivided, omitted, or additional components can be added according to specific needs. Furthermore, Figure 2A and Figure 2B This example illustrates a transmit and receive path that can be used in a wireless network. Any other suitable architecture can be used to support wireless communication in a wireless network.

[0047] Figure 3A An exemplary UE 116 according to an embodiment of this disclosure is shown. Figure 3A The UE 116 embodiment shown is for illustrative purposes only. Figure 1 UEs 111-115 can have the same or similar configurations. However, UEs have multiple configurations. Figure 3A This disclosure is not intended to limit the scope to any particular implementation of the UE.

[0048] like Figure 3A As shown, UE 116 includes an antenna 305, a transceiver 310, and a microphone 320. UE 116 also includes a speaker 330, a processor 340, an input / output (I / O) interface (IF) 345, an input device 350, a display 355, and a memory 360. The memory 360 includes an operating system (OS) 361 and one or more applications 362.

[0049] Transceiver 310 receives an input RF signal from the gNB of network 100 via antenna 305. Transceiver 310 down-converts the input RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by a receive (RX) processing circuit in transceiver 310 and / or processor 340, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuit sends the processed baseband signal to speaker 330 (e.g., for voice data) or to processor 340 (e.g., for web browsing data).

[0050] The TX processing circuitry in transceiver 310 and / or processor 340 receives analog or digital voice data from microphone 320, or other output baseband data (such as web page data, email, or interactive video game data) from processor 340. The TX processing circuitry encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. Transceiver 310 up-converts the baseband or IF signal into an RF signal, which is then transmitted via antenna 305.

[0051] Processor 340 may include one or more processors or other processing devices and executes OS 361 stored in memory 360 to control the overall operation of UE 116. For example, processor 340 may control transceiver 310 to receive downlink channel signals and transmit uplink channel signals according to known principles. In some embodiments, processor 340 includes at least one microprocessor or microcontroller.

[0052] Processor 340 is also capable of executing other processes and programs residing in memory 360, such as the UE-initiated early timing advance fetch process discussed in more detail below. Processor 340 may move data into or out of memory 360 as needed for executing processes. In some embodiments, processor 340 is configured to execute application 362 based on OS 361 or in response to signals received from gNB or operator. Processor 340 is also coupled to I / O interface 345, which provides UE 116 with the ability to connect to other devices, such as laptop computers and handheld computers. I / O interface 345 is the communication path between these accessories and processor 340.

[0053] The processor 340 is also coupled to an input device 350 (e.g., a touchscreen, keypad, etc.) and a display 355. The operator of the UE 116 can use the input device 350 to input data into the UE 116. The display 355 may be a liquid crystal display, a light-emitting diode display, or other display capable of displaying text and / or at least limited graphics (such as from a website).

[0054] The memory 360 is coupled to the processor 340. A portion of the memory 360 may include random access memory (RAM), and another portion of the memory 360 may include flash memory or other read-only memory (ROM).

[0055] although Figure 3A An example of UE 116 is shown, but it is possible to modify it. Figure 3A Make various changes. For example, Figure 3A The various components can be combined, further subdivided, omitted, or additional components can be added according to specific needs. As a specific example, processor 340 can 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 can include any number of transceivers and signal processing chains and can be connected to any number of antennas. Furthermore, although... Figure 3A The UE 116 is shown to be configured as a mobile phone or smartphone, but the UE can be configured to operate as other types of mobile or fixed devices.

[0056] Figure 3B An exemplary gNB 102 according to an embodiment of this disclosure is shown. Figure 3B The gNB 102 embodiment shown is for illustrative purposes only, and Figure 1 gNBs 101 and 103 can have the same or similar configurations. However, gNBs have multiple configurations, and Figure 3B This disclosure is not intended to limit the scope to any particular implementation of gNB.

[0057] like Figure 3B As shown, the gNB 102 includes multiple antennas 370a-370n, multiple transceivers 372a-372n, a controller / processor 378, a memory 380, and a backhaul or network interface 382.

[0058] Transceivers 372a-372n receive input RF signals (such as signals transmitted by the UE in network 100) from antennas 370a-370n. Transceivers 372a-372n down-convert the input RF signals to generate IF or baseband signals. The IF or baseband signals are processed by receive (RX) processing circuitry in transceivers 372a-372n and / or controller / processor 378, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. Controller / processor 378 may further process the baseband signals.

[0059] The transmit (TX) processing circuitry in transceivers 372a-372n and / or controller / processor 378 receives analog or digital data (such as voice data, web page data, email, or interactive video game data) from controller / processor 378. The TX processing circuitry encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. Transceivers 372a-372n up-convert the baseband or IF signal into an RF signal, which is then transmitted via antennas 370a-370n.

[0060] The controller / processor 378 may include one or more processors or other processing devices to control the overall operation of the gNB 102. For example, the controller / processor 378 may control the transceivers 372a-372n to receive uplink (UL) channel signals and transmit downlink (DL) channel signals according to known principles. The controller / processor 378 may also support additional functions, such as more advanced wireless communication capabilities. For example, the controller / processor 378 may support beamforming or directional routing operations, where output / input signals from / to multiple antennas 370a-370n are weighted differently to effectively direct the output signal in a desired direction. The controller / processor 378 in the gNB 102 may support any of a variety of other functions.

[0061] The controller / processor 378 is also capable of executing programs and other processes residing in memory 380, such as the OS, and processes for supporting early timing advance fetching initiated by the UE, as discussed in more detail below. The controller / processor 378 can move data into or out of memory 380 as needed by the executing processes.

[0062] The controller / processor 378 is also coupled to a backhaul or network interface 382. The backhaul or network interface 382 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or over a network. Interface 382 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), interface 382 allows 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, interface 382 allows 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). Interface 382 includes any suitable structure that supports communication via a wired or wireless connection, such as an Ethernet interface or transceiver.

[0063] Memory 380 is coupled to controller / processor 378. A portion of memory 380 may include RAM, and another portion of memory 380 may include flash memory or other ROM.

[0064] although Figure 3B An example of gNB 102 is shown, but it is possible to compare it with other models. Figure 3B Various changes can be made. For example, gNB 102 may include... Figure 3B Any quantity of each component shown. Furthermore, Figure 3B The various components can be combined, further subdivided, omitted, or additional components can be added according to specific needs.

[0065] The 3rd Generation Partnership Project (3GPP) has developed technical specifications and standards to define the new 5G radio access technology, namely 5G NR (New Radio). Mobility handling is a critical aspect of any mobile communication system, including 5G systems. For user equipment (UE) in connected mode, mobility is controlled by the network with the assistance of the UE to maintain good connection quality. Based on the UE's reported measurements of radio link quality to the serving cell and neighboring cells, when the connection quality between the UE and the serving cell deteriorates, the network can hand over the UE to a neighboring cell that can provide better radio conditions. In Release 15 of NR, the basic mechanisms and procedures for network-controlled mobility in connected mode were developed. In Release 16 of NR, enhancements to network-controlled mobility in connected mode were introduced to reduce connection interruptions during handover. Specifically, two enhanced handover mechanisms were developed: Conditional Handover (CHO) and Dual Active Protocol Stack (DAPS).

[0066] In the CHO procedure, after receiving the CHO configuration in a Radio Resource Control (RRC) reconfiguration message containing configurations for multiple candidate cells, the UE begins evaluating the CHO execution conditions of the candidate cells. If at least one CHO candidate cell meets the corresponding CHO execution conditions, the UE separates from the source cell, applies the configuration, synchronizes with the target cell, and completes the CHO procedure by sending an RRC reconfiguration complete message to the target cell. The UE releases the stored CHO configuration after the handover procedure is successfully completed.

[0067] More specifically, a CHO is defined as a handover performed by the UE when one or more handover execution conditions are met. The UE begins evaluating the execution conditions after receiving the CHO configuration and stops evaluating the execution conditions after performing the handover.

[0068] The following principles apply to CHO: The CHO configuration includes the configuration of CHO candidate cells generated by the candidate gNB and the execution conditions generated by the source gNB.

[0069] Execution conditions may include one or two trigger conditions. Only a single reference signal (RS) type is supported, and for the evaluation of CHO execution conditions for a single candidate cell, up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) can be configured simultaneously.

[0070] Before any CHO execution conditions are met, the UE executes the HO procedure after receiving a handover (HO) command (without CHO configuration), regardless of any previously received CHO configuration.

[0071] When executing CHO, that is, from the time the UE starts synchronizing with the target cell, the UE does not listen to the source cell.

[0072] Similar to intra-NR RAN handover, in intra-NR RAN CHO, the preparation and execution phases of the conditional handover process are performed without involving the 5G core network (5GC), meaning preparation messages are exchanged directly between gNBs. During the conditional handover completion phase, the release of resources at the source gNB is triggered by the target gNB. Figure 4 This illustrates a basic condition switching scenario where neither AMF nor UPF changes.

[0073] Figure 4 An exemplary condition switching operation 400 according to an embodiment of this disclosure is shown. Figure 4 The operational examples shown are for illustrative purposes only. Figure 4 One or more components shown may be implemented as dedicated circuitry configured to perform the function, or one or more components may be implemented by one or more processors executing instructions to perform the function. Other embodiments of the conditional switching operation may be used without departing from the scope of this disclosure.

[0074] Figure 4 The example begins with step 0. In step 0, the UE context within the source gNB 404 contains information about roaming and access restrictions, which is provided either during connection establishment or at the time of the last tracking area update. In step 1, the source gNB 404 configures the UE measurement procedure, and UE 402 reports according to the measurement configuration. In step 2, the source gNB 404 decides to use a CHO.

[0075] In step 3, the source gNB requests a CHO from one or more candidate cells belonging to one or more candidate gNBs 406 and 408. The CHO request message is sent for each candidate cell. In step 4, the target gNBs 406 and 408 may perform admission control. If slice information has been sent to the target gNB, slice-aware admission control should be performed. If a PDU session is associated with an unsupported slice, the target gNB should reject such a PDU session. In step 5, candidate gNBs 406 and 408 send a CHO response (HO request acknowledgment) message containing the configuration of the CHO-to-candidate cell to the source gNB 404. The CHO response message is sent for each candidate cell.

[0076] In step 6, the source gNB 404 sends an RRC Reconfiguration message to the UE 402. This message contains the configuration of the CHO candidate cell and the CHO execution conditions. Other reconfigurations from the source gNB 404 may follow the CHO configuration of the candidate cell. The CHO candidate cell configuration cannot contain DAPS handover configuration. In step 7, the UE 402 sends an RRC Reconfiguration Complete message to the source gNB 404. In step 7a, if early data forwarding is applied, the source gNB 404 sends an early state transition message.

[0077] In step 8, after receiving the CHO configuration, UE 402 maintains its connection with the source gNB 404 and begins evaluating the CHO execution conditions for candidate cells. If at least one CHO candidate cell meets the corresponding CHO execution conditions, the UE disconnects from the source gNB 404, applies the corresponding configuration stored for the selected candidate cell, synchronizes with the candidate cell, and completes the RRC handover procedure by sending an RRC reconfiguration complete message to the target gNB (e.g., target gNB 406). The UE releases the stored CHO configuration after the RRC handover procedure is successfully completed.

[0078] In step 8a, the target gNB (e.g., target gNB 406) sends a handover success message to the source gNB 404 to notify it that UE 402 has successfully accessed the target cell. In response, in step 8b, the source gNB 404 sends an SN state transition message. Delayed data forwarding can be initiated immediately upon receiving the handover success message. In step 8c, the source gNB 404 sends handover cancellation messages to other signaling connections or other candidate target gNBs (if any) to cancel the CHO for the UE.

[0079] although Figure 4 An exemplary condition switching operation 400 is shown, but it is possible to... Figure 4Various changes were made. For example, although it was shown as a series of steps, Figure 4 The various steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0080] For connected mobility, traditional handover (e.g., CHO) is initiated by the network based on Layer 3 (L3) measurements via higher-layer signaling (e.g., RRC messages). However, this process involves significant latency, signaling overhead, and downtime, which can be critical issues in scenarios with frequent handovers (e.g., UEs in high-speed vehicles and FR2 deployment scenarios). There is a desire to reduce the overhead and / or latency and downtime in the handover process, for example, through Layer 1 / L2 triggered mobility (LTM), where handover can be triggered by L1 / L2 signaling based on L1 measurements. More specifically, LTM refers to a mobility mechanism where a UE hands over from a source cell to a target cell via beam switching, where the beam switching decision is based on L1 measurements of beams in configured candidate cells, and the cell handover can be triggered by L1 / L2 signaling from the network (NW) or by the fulfillment of pre-configured conditional events (e.g., in a Conditional LTM (CLTM) procedure). This can be referred to as cell handover conditions.

[0081] For LTM triggered by L1 / L2 signaling from the network, the network may request the UE to perform early timing advance (TA) acquisition of the candidate cell before cell handover. Early TA acquisition can be triggered by a PDCCH command or by UE-based TA measurement. The network indicates in the cell handover command whether the UE should access the target cell via a random access (RA)-based cell handover procedure if no TA value is provided, or whether the UE should access the target cell via PUSCH transmission using the indicated TA value. Otherwise, the UE should access the target cell via a cell handover procedure without RA.

[0082] When a cell handover to the target cell is performed during a CHO operation, the UE obtains the target cell's TA by executing the RA procedure, which introduces cell handover latency. To reduce latency, the TA can be obtained by the UE in advance before the cell handover is performed.

[0083] This disclosure specifies a procedure for UE-initiated early TA acquisition for a non-serving cell. The UE-initiated early TA acquisition for a non-serving cell can be applied to CHO procedures, CLTM procedures, or inter-cell multi-TRP operations.

[0084] Figure 5 An exemplary UE process 500 for early TA acquisition for a non-serving cell initiated by a UE according to an embodiment of this disclosure is shown. Figure 5 The illustrated process examples are for illustrative purposes only. Figure 5 One or more components shown may be implemented as dedicated circuitry configured to perform the functions described herein, or one or more components may be implemented by one or more processors executing instructions to perform the functions described herein. Other embodiments of the UE-initiated early TA acquisition process for a non-serving cell may be used without departing from the scope of this disclosure.

[0085] exist Figure 5 In the example, procedure 500 begins with operation 505. In operation 505, the UE receives an early TA configuration for a non-serving cell from the serving cell. Here, a non-serving cell may refer to a candidate cell with conditional reconfiguration provided for one or more operations such as CHO, CLTM, Conditional Primary / Secondary Cell Group (SCG) Cell Addition and Change (CPAC), CHO with a Candidate Secondary Cell Group (SCG), or a non-serving cell (e.g., an additional cell) in an inter-cell multi-TRP operation. A configuration for the non-serving cell may be provided and stored by the UE. In operation 510, if RACH resources for early TA acquisition are provided for the non-serving cell, the UE decides to perform early TA acquisition for that cell and sends Msg1 / MsgA in a contention-free random access (CFRA) procedure using the early TA RACH resources. For example, if RACH resources for a CLTM candidate cell are available, but the TA is not acquired or is invalid, the UE performs early TA acquisition for that candidate cell. In another example, if the RACH resources of a CLTM candidate cell are unavailable, the TA is not acquired, or is invalid, and the CLTM execution conditions are met, the UE performs an early TA acquisition for that candidate cell. In operation 515, the UE receives the TA for the non-serving cell in the RAR or MAC CE and maintains the time alignment timer (TAT) for the timing advance group (TAG) used for that TA. In operation 520, when accessing a non-serving cell, if the TA for that cell is not acquired or has expired, the UE performs RA; or, if the TA for that cell is acquired and valid, the UE skips RA. Here, accessing a non-serving cell can refer to a handover to that cell due to mobility (e.g., via CHO or CLTM procedures), or to receiving signals from and / or sending signals to the non-serving cell using resources associated with the non-serving cell (e.g., via inter-cell multi-TRP operations).

[0086] In one embodiment, at operation 505, the early TA configuration for a non-serving cell may be provided by an RRC reconfiguration message from the serving cell. This early TA configuration may include an RA configuration and / or TAG configuration and / or a Cell Radio Network Temporary Identifier (C-RNTI) associated with the non-serving cell. The RA configuration may include RACH resources (e.g., for four-step RA or two-step RA), UL and / or DL ​​configurations (e.g., for PDCCH, PDSCH, PUCCH, PUSCH), which provide information including carrier, bandwidth portion (BWP), search space, and control resource set, applied to the RA toward the non-serving cell. The non-serving cell may assign different RACH configurations (including RACH resources) to different serving cells. The non-serving cell may identify the serving cell based on a received PRACH preamble.

[0087] In one example, a contention-free random access (CFRA) RACH resource for early TA acquisition can be provided, which may include PRACH timings, and / or the number of SSBs per PRACH timing, and / or SSB indices, and / or CSI-RS indices, and / or RA preamble indices, and / or PRACH timing mask indices, and / or a list of PRACH timings, such that the RACH resource is dedicated to the UE's early TA acquisition for a non-serving cell. A valid duration can be configured for the CFRA RACH resource of a candidate cell, indicating how long the UE can consider the CFRA RACH resource valid and available for early TA acquisition for the candidate cell. In another example, a cell-specific RACH resource shared by the UE can be provided for contention-based random access (CBRA) for early TA acquisition. The candidate cell's TAG configuration may include a TAG indicator (TAG ID) and / or a time alignment timer parameter to indicate the duration of the time alignment timer.

[0088] For RACH configuration used in non-serving cells, one or more of the following parameters can be configured: prach-ConfigurationIndex: The set of available PRACH opportunities for random access preamble transmission for Msg1. These parameters also apply to MSGA PRACH if PRACH opportunities are shared between two-step and four-step RA types; msgA-PRACH-ConfigurationIndex: The set of available PRACH opportunities for random access preamble transmission of MSGA in two-step RA type; preambleReceivedTargetPower: Initial random access preamble power for four-step RA type; msgA-PreambleReceivedTargetPower: Initial random access preamble power for two-step RA type; rsrp-ThresholdSSB: RSRP threshold for SSB selection in four-step RA type; rsrp-ThresholdCSI-RS: RSRP threshold for CSI-RS selection in four-step RA type; msgA-RSRP-ThresholdSSB: RSRP threshold for SSB selection in two-step RA type; rsrp-ThresholdSSB-SUL: The RSRP threshold used for selecting between NUL and SUL carriers; msgA-RSRP-Threshold: The RSRP threshold used to make a choice between two-step and four-step RA types when random access resources for both two-step and four-step RA types are configured in the UL BWP. msgA-CFRA-PUSCH: PUSCH resource configuration for msgA CFRA; msgA-TransMax: The maximum number of MSGA transmissions when both four-step and two-step RA types are configured with random access resources; powerRampingStep: Power Ramp-up Factor; msgA-PreamblePowerRampingStep: The power ramping factor of the MSGA preamble; powerRampingStepHighPriority: Power ramp-up factor under priority random access procedures; scalingFactorBI: A scaling factor used to prioritize random access procedures; ra-PreambleIndex: Random access preamble; ra-ssb-OccasionMaskIndex: Defines the PRACH timing associated with the SSB in which a MAC entity may transmit a random access preamble; msgA-SSB-SharedRO-MaskIndex: Indicates a subset of four-step RA type PRACH times for each SSB that are shared with two-step RA type PRACH times; ra-OccasionList: Defines the PRACH timing associated with CSI-RS in which MAC entities can transmit random access preambles; preambleTransMax: The maximum number of random access preamble transmissions; ssb-perRACH-OccasionAndCB-PreamblesPerSSB: Defines the number of SSBs mapped to each PRACH timing for a four-step RA type, and the number of contention-based random access preambles mapped to each SSB; msgA-CB-PreamblesPerSSB-PerSharedRO: Defines the number of contention-based random access preambles mapped to each SSB for the two-step RA type when the PRACH timing is shared between two-step and four-step RA types; msgA-SSB-PerRACH-OccasionAndCB-PreamblesPerSSB: Defines the number of SSBs used for mapping two-step RA types to each PRACH timing, and the number of contention-based random access preambles mapped to each SSB. msgA-PUSCH-ResourceGroupA: Defines the MSGA PUSCH resource that the UE should use when performing MSGA transmission using Random Access Preamble Group A; msgA-PUSCH-ResourceGroupB: Defines the MSGA PUSCH resource that the UE should use when performing MSGA transmission using Random Access Preamble Group B; msgA-PUSCH-Resource-Index: Identifies the index of the PUSCH resource used for MSGA in the case of contention-free random access using the two-step RA type; If groupB is configured, then random access preamble group B is configured for the four-step RA type. In the contention-based random access preambles associated with the SSB, the first numberOfRA-PreamblesGroupA random access preambles included in groupBconfigured belong to random access preamble group A. The remaining random access preambles associated with the SSB belong to random access preamble group B (if configured). If groupB-ConfiguredTwoStepRA is configured, then random access preamble group B is configured for the two-step RA type. In the contention-based random access preambles of the two-step RA type associated with the SSB, the first numberOfRA-PreamblesGroupA random access preambles contained in groupB-ConfiguredTwoStepRA belong to random access preamble group A. The remaining random access preambles associated with the SSB belong to random access preamble group B (if configured). If random access preamble group B is configured for the four-step RA type: - ra-Msg3SizeGroupA: Used to determine the threshold for a random access preamble group of the four-step RA type; - msg3-DeltaPreamble:?PREAMBLE_Msg3; - messagePowerOffsetGroupB: Power offset used for selecting the preamble included in groupBconfigured; - numberOfRA-PreamblesGroupA: Defines the number of random access preambles in group A for each SSB, contained in groupBconfigured; If random access preamble group B is configured for a two-step RA type: - msgA-DeltaPreamble:?MsgA_PUSCH; - messagePowerOffsetGroupB: Power offset used for selecting the preamble contained in groupB-ConfiguredTwoStepRA; - numberOfRA-PreamblesGroupA: Defines the number of random access preambles in groupA for each SSB contained in groupB-ConfiguredTwoStepRA; - ra-MsgA-SizeGroupA: Used to determine the threshold for a random access preamble group of two-step RA type; Random access preamble and / or PRACH timing (if any) used for early TA acquisition; ra-ResponseWindow: The time window for listening to RA responses (primary cell (SpCell) only); the network can configure a value greater than or equal to 10 milliseconds when Msg2 is transmitted in the licensed spectrum for early TA acquisition; ra-ContentionResolutionTimer: Contention resolution timer (SpCell only); and msgB-ResponseWindow: Time window for listening to two-step RA type RA responses (SpCell only).

[0089] In one embodiment, at operation 505, the UE maintains a variable, denoted as Var-1, for storing early TA configurations. For each entry received in the list of non-serving cells (e.g., candidate cells), if Var-1 contains an entry with a given ID of that non-serving cell, and if that entry contains early TA configurations, the UE replaces the existing early TA in Var-1 with the received early TA configuration for that ID. If Var-1 does not contain an entry with a given ID of that non-serving cell, the UE adds a new entry for that ID in Var-1 and stores the received early TA configuration for that ID.

[0090] In one embodiment, during operation 510, if a valid duration of CFRARACH channel resources is configured for a non-serving cell in the early TA configuration, the UE starts a valid timer after receiving the early TA configuration for that cell and sets the timer duration to the indicated valid duration. When the valid timer associated with the non-serving cell is running, the UE considers the CFRARACH resources of the candidate cell to be valid and usable for sending PRACH to the candidate cell for early TA acquisition (whether initially acquiring the cell's TA or subsequently updating the cell's TA). When the valid timer associated with the non-serving cell expires, the UE releases the CFRARACH resources of that cell and / or releases the early TA configuration associated with that cell.

[0091] In one embodiment, during operation 510, if an early TA configuration is provided for a candidate cell, and the RACH resources (e.g., four-step or two-step RA) of the CFRA or CBRA in the early TA configuration are included / configured / provided / available / valid, then the UE initiates an RA procedure by using the RACH resources of the CFRA or CBRA to send a PRACH to the candidate cell in order to obtain the TA of the candidate cell.

[0092] If firstActiveDownlinkBWP-Id and / or firstActiveUplinkBWP-Id are configured in the early TA configuration for a non-serving cell, the DL BWP and / or UL BWP indicated by firstActiveDownlinkBWP-Id and / or firstActiveUplinkBWP-Id, respectively, are active for the RA procedure used for early TA acquisition. Otherwise, if firstActiveDownlinkBWP-Id and / or firstActiveUplinkBWP-Id are not configured in the early TA configuration for a non-serving cell, the initial downlink BWP and initial uplink BWP are used for the RA procedure used for early TA acquisition.

[0093] If CFRA resources for a four-step RA type are explicitly provided in the early TA configuration for the BWP selected for early TA acquisition, the UE performs a four-step RA type RA. If CFRA resources for a two-step RA type are explicitly provided in the early TA configuration for the BWP selected for early TA acquisition, the UE performs a two-step RA type RA. If the RA type is a four-step RA, the UE sends a PRACH preamble to the non-serving cell in Msg1. If the RA type is a two-step RA, the UE sends a PRACH preamble and PUSCH to the non-serving cell in MsgA, where the MsgA PUSCH may contain a C-RNTI MAC CE. In one example, a C-RNTI associated with the non-serving cell may be assigned to the UE, this identifier being provided in the early TA configuration or in a configuration for the non-serving cell (e.g., radio resource control reconfiguration) (e.g., in Operation 505), and the UE may include the non-serving cell's C-RNTI in the C-RNTI MAC CE of the MsgA PUSCH. In another example, the UE may include the C-RNTI associated with the serving cell in the C-RNTI MAC CE of the MsgA PUSCH.

[0094] For PRACH preamble transmission in Msg1 / MsgA, if an SSB and / or preamble index is explicitly provided in the CFRA resources for early TA configuration of a non-serving cell, the UE selects an SSB and sets the preamble index corresponding to the selected SSB. If a CSI-RS and / or preamble index is explicitly provided in the CFRA resources for early TA configuration of a non-serving cell, the UE selects a CSI-RS and sets the preamble index corresponding to the selected SSB. The UE determines the next available PRACH timing from the PRACH timings corresponding to the selected SSB allowed by the constraints given in the configuration. The UE transmits Msg1 using the selected PRACH timing and the calculated RA-RNTI.

[0095] For MsgA PUSCH transmission, the UE selects a PUSCH timing from the PUSCH timings configured in msgA-CFRA-PUSCH corresponding to the PRACH slot of the selected PRACH timing, based on the msgA-PUSCH-Resource-Index corresponding to the selected SSB. The UE determines the UL authorization and associated HARQ information for the MsgA payload in the selected PUSCH timing. The UE transmits the UL authorization and associated HARQ information to the HARQ entity. The UE uses the selected PRACH timing, the associated PUSCH resources for MsgA, and the calculated RA-RNTI and MsgB-RNTI to transmit MsgA.

[0096] In one embodiment, after sending Msg1 / MsgA for early TA acquisition to the candidate cell in operation 515, the UE executes the procedure of receiving Msg2 / MsgB from the serving cell, wherein the non-serving cell may send the TA and RA-RNTI for the received PRACH preamble to the serving cell so that the serving cell can notify the UE of the TA of the non-serving cell. Optionally, after sending Msg1 / MsgA for early TA acquisition to the candidate cell, if UL and / or DL ​​configurations for the non-serving cell are configured, the UE executes the procedure of receiving Msg2 / MsgB from the non-serving cell.

[0097] If Msg1 in the four-step CFRA is sent, the UE listens to the serving cell's PDCCH or (if configured) the non-serving cell's PDCCH for the RAR identified by the RA-RNTI during the ra-ResponseWindow operation. If a valid downlink allocation for the RA-RNTI is received on the PDCCH, and the received transport block (TB) is successfully decoded, and the RAR contains a MAC sub-PDU with a random access preamble identifier (RAPID) corresponding to the sent preamble index, the UE considers the RAR reception successful. If CFRA was performed for an early TA acquisition and the RAR reception is successful, the UE considers the RA procedure to have completed successfully.

[0098] If MsgA is sent in both steps of the CFRA, the UE listens to the serving cell's PDCCH or (if configured) the non-serving cell's PDCCH for the RAR identified by MSGB-RNTI during the msgB-ResponseWindow operation. If MsgA contains C-RNTI MAC CE, the UE also listens to the serving cell's PDCCH or (if configured) the non-serving cell's PDCCH for the RAR identified by C-RNTI during the msgB-ResponseWindow operation.

[0099] In one scenario, if a reception notification is received from a lower layer for a PDCCH transmission of the serving cell's PDCCH or (if configured) a non-serving cell's PDCCH, and if the MsgA contains a C-RNTI MAC CE, and if a downlink allocation for the C-RNTI is received on the PDCCH and the received TB is successfully decoded, and if the MAC PDU contains a MAC CE (e.g., an Absolute Timing Advance Command (TAC) MAC CE or a TA MAC CE or a new MAC CE for early TA acquisition), the UE processes the received TAC, considers the RAR reception successful, stops the msgB-ResponseWindow, and considers the RA procedure for early TA acquisition to have been successfully completed. For example, this disclosure provides a new MAC CE for early TA acquisition, identified by a Logical Channel Identifier (LCID) or an Extended LCID (eLCID) (e.g., ...). Figure 7 (As shown). The MAC CE may include the absolute TA of the non-serving cell, and / or the ID of the non-serving cell that identifies the cell to which the TA contained in the MAC CE is applied, and / or the TAG ID of the non-serving cell.

[0100] In another scenario, if a reception notification for a PDCCH transmission of the serving cell or (if configured) a non-serving cell's PDCCH is received from a lower layer, and if MsgA does not contain a C-RNTI MAC CE, if a valid downlink allocation for the MSGB-RNTI is received on the PDCCH and the received TB is successfully decoded, and if MsgB contains a fallback RAR MAC sub-PDU, and if the RAPID in the MAC sub-PDU matches the transmitted preamble index, then the UE considers the RAR reception successful. If CFRA was performed for early TA acquisition and the RAR reception is successful, then the UE considers the RA procedure to have been successfully completed.

[0101] In the RAR (e.g., MAC RAR, fallback RAR) or TAC MAC CE or absolute TAC MAC CE included in Msg2 or MsgB, the UE considers the TA for the non-serving cell in the TAC. In another example, if the RAR (e.g., MAC RAR, fallback RAR) or TAC MAC CE or absolute TAC MAC CE contains a TAG ID that matches a configured TAG ID associated with a non-serving cell in an earlier TA configuration, the UE considers the TAC to be for that non-serving cell. If the TA for the non-serving cell is obtained, the UE applies the TA to that non-serving cell and (if any) other cells that belong to a TAG configured in an earlier TA configuration associated with a candidate cell. The UE starts or restarts the time alignment timer for that TAG and sets the timer duration to the value indicated by the timerAlignmentTimer parameter for the non-serving cell in the earlier TA configuration.

[0102] The UE may ignore the UL grant and / or temporary C-RNTI contained in the RAR (e.g., MAC RAR, fallback RAR) included in Msg2 or MsgB. For example, if an RA procedure for a non-serving cell is performed on an uplink carrier without a configured PUSCH, the UE may ignore the received UL grant. Otherwise, the UE processes the received UL grant value and indicates it to the lower layer. Alternatively, the UE processes the received UL grant value in the RAR and indicates it to the lower layer for initial PUSCH transmission to the non-serving cell after early TA acquisition.

[0103] In another embodiment, in operation 510, if the CFRA is initiated by the UE for early TA acquisition of a CLTM candidate cell, the UE considers the RA procedure to have been successfully completed after sending the random access preamble. In operation 515, the UE receives a MAC CE (e.g., an absolute timing advance command MAC CE, a TAC MAC CE, or a MAC CE for early TA acquisition) containing the TA of the candidate cell from the current serving cell.

[0104] The UE can perform operations 510 and 515 to initially acquire the TA (Target Acquisition) of a non-serving cell, or subsequently update the TA of a non-serving cell when the time alignment timer of the non-serving cell expires (i.e., the previous TA is invalid). Whenever the TA of a non-serving cell is acquired or updated, the MAC entity can indicate to the upper layer the earlier TA for that non-serving cell. Whenever the associated time alignment timer expires, the MAC CE entity can indicate to the upper layer that the earlier TA for that non-serving cell has expired.

[0105] As an alternative to operations 510 and 515, if no CFRA resource is explicitly provided and cell public RACH resources are available, the UE may use the cell public RACH resources configured in the early TA configuration to perform contention-based RA (CBRA) to obtain TA for a non-serving cell. An exemplary embodiment is as follows: Figure 6 As shown.

[0106] although Figure 5 An exemplary UE procedure 500 for early TA acquisition of a non-serving cell initiated by a UE is shown, but it can be modified accordingly. Figure 5 Various changes were made. For example, although it was shown as a series of steps, Figure 5 The various steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0107] Figure 6 An exemplary UE procedure 600 for performing a four-step CBRA for early TA acquisition with no serving cell participation is shown according to an embodiment of this disclosure. Figure 6 The illustrated process examples are for illustrative purposes only. Figure 6 One or more components shown may be implemented as dedicated circuitry configured to perform the functions described, or one or more components may be implemented by one or more processors executing instructions to perform the functions. Other embodiments of the UE procedure for performing a four-step CBRA for early TA acquisition with no serving cell participation may be used without departing from the scope of this disclosure.

[0108] exist Figure 6 In the example, if the CBRA resource for the four-step RA type is explicitly provided in the early TA configuration for early TA to obtain the selected BWP, then UE 601 performs the RA of the four-step RA type.

[0109] exist Figure 6 In the example, procedure 600 begins with operation 605. In operation 605, UE 601 performs a four-step RA of type RA. UE 601 uses the CBRA RACH resources included in the early TA configuration to send the PRACH preamble. UE 601 selects the SSB, and / or (if configured) the PRACH preamble group, and / or the PRACH preamble index, and / or the PRACH timing according to the CBRA procedure.

[0110] During operation 610, UE 601 listens to the PDCCH of a non-serving cell for the RAR identified by the RA-RNTI, where the PDCCH of the non-serving cell 603 can be configured in the early TA configuration. If a valid downlink allocation is received on the PDCCH for that RA-RNTI and the received TB is successfully decoded, and if the RAR contains a MAC sub-PDU with a RAPID corresponding to the transmitted preamble index, the UE considers the RAR reception successful.

[0111] In operation 615, if the RAR is successfully received, UE 601 processes the TA, UL grant, and TC-RNTI contained in the MAC RAR. UE 601 stores the TA. UE 601 processes the UL grant received in the RAR and instructs it to the lower layer for Msg3 transmission. UE 601 sets the temporary _C-RNTI (TEMPORARY_C-RNTI) to the value of the TC-RNTI received in the RAR.

[0112] In operation 620, UE 601 uses a UL grant with a C-RNTI MAC CE included in the PUSCH to send Msg3 to non-serving cell 603, where the C-RNTI is for non-serving cell 603. The C-RNTI associated with non-serving cell 603 may be assigned to UE 601, and this identifier may be provided in an early TA configuration or in a configuration for non-serving cell 603 (e.g., RRC reconfiguration). Figure 5 Operation 505).

[0113] In operation 625, once message 3 is sent to non-serving cell 603, UE 601 listens to the PDCCH of non-serving cell 603 during the ra-ResponseWindow operation, regardless of whether a measurement gap may occur, where the PDCCH of non-serving cell 603 can be configured in the early TA configuration.

[0114] In operation 625, in one example, if the CBRA is initiated for early TA acquisition and Msg3 contains the C-RNTI of the non-serving cell, and if the PDCCH received in operation 625 addresses the C-RNTI, then UE 601 considers the contention resolution successful, stops the ra-ContentionResolutionTimer, discards the TEMPORARY_C-RNTI, and considers the CBRA procedure for early TA acquisition to have been successfully completed.

[0115] In operation 625, in another example, if Msg3 contains a Common Control Channel (CCCH) Service Data Unit (SDU), and the PDCCH received in operation 625 addresses its Temporary _C-RNTI, and if the MAC PDU is successfully decoded, the UE stops the ra-ContentionResolutionTimer. In operation 630, if the MAC PDU contains an Early TA Contention Resolution Identifier (MAC CE) (e.g., ...), the UE stops the ra-ContentionResolutionTimer. Figure 7 As shown in Figure 601, if the UE contention resolution identifier in the MAC CE matches the CCCH SDU transmitted in Msg3, and the C-RNTI in the MAC CE matches the C-RNTI value transmitted in Msg3, then UE 601 considers the contention resolution successful, discards the temporary C-RNTI (TEMPORARY_C-RNTI), and considers the CBRA procedure for early TA acquisition to have been successfully completed. Alternatively, in operation 630, if the MAC PDU contains the UE contention resolution identifier MAC CE, and the UE contention resolution identifier in the MAC CE matches the CCCH SDU transmitted in Msg3, and if the MAC PDU also contains a C-RNTI MAC CE that matches the C-RNTI value transmitted in Msg3, then UE 601 considers the contention resolution successful, discards the temporary C-RNTI (TEMPORARY_C-RNTI), and considers the CBRA procedure for early TA acquisition to have been successfully completed. An example of the early TA contention resolution identifier MAC CE is shown below. Figure 7 As shown.

[0116] Figure 7 An exemplary early TA contention resolution identifier MAC CE 700 according to an embodiment of this disclosure is shown. Figure 7 The Early TA Contention Resolution Identifier (MAC CE) embodiment shown is for illustrative purposes only. Other embodiments of the Early TA Contention Resolution Identifier (MAC CE) may be used without departing from the scope of this disclosure.

[0117] exist Figure 7 In the example, the early TA contention resolution identifier MAC CE is identified by the MAC subheader with LCID or eLCID. Figure 7 The MAC CE has a fixed size of 64 bits and includes the following defined fields: UE Contention Resolution Identifier: This field contains the UL CCCH SDU. If the UL CCCH SDU is longer than 48 bits, this field contains the first 48 bits of the UL CCCH SDU.

[0118] C-RNTI: This field contains the C-RNTI of the MAC entity. The length of this field is 16 bits.

[0119] although Figure 7 An exemplary early TA contention resolution identifier MAC CE 700 is shown, but it is possible to... Figure 7 Various changes can be made. For example, the UE contention resolution identifier field, C-RNTI field, etc., can be modified according to specific requirements.

[0120] If the CBRA is successfully completed, UE 601 considers the TA in the RAR to be for non-serving cell 603. In another example, if the RAR contains a TAG ID that matches the TAG ID of a non-serving cell associated with an earlier TA configuration, UE 601 considers the TA to be for non-serving cell 603. If the TA for a non-serving cell is obtained, UE 601 will apply the TA to that non-serving cell (i.e., non-serving cell 603) and (if any) other cells (e.g., SpCell 602) that belong to a TAG configured in an earlier TA configuration associated with the candidate cell (i.e., non-serving cell 603). UE 601 starts or restarts the time alignment timer for that TAG and sets the timer duration to the value indicated by the timerAlignmentTimer parameter for the non-serving cell in the earlier TA configuration. If the ra-ContentionResolutionTimer expires, UE 601 discards the TEMPORARY_C-RNTI, deeming the contention resolution unsuccessful, and discards the TA in the random access response.

[0121] although Figure 6 An exemplary UE procedure 600 for a four-step CBRA for early TA acquisition without serving cell involvement is shown, but it can be modified accordingly. Figure 6 Various changes were made. For example, although it was shown as a series of steps, Figure 6 The various steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0122] Figure 8 An exemplary UE procedure 800 for a four-step CBRA with the participation of the serving cell is shown according to an embodiment of this disclosure. Figure 8 The illustrated process examples are for illustrative purposes only. Figure 8 One or more components shown may be implemented as dedicated circuitry configured to perform the functions described, or one or more components may be implemented by one or more processors executing instructions to perform the functions. Other embodiments of the four-step CBRA UE procedure involving the serving cell for early TA acquisition may be used without departing from the scope of this disclosure.

[0123] exist Figure 8In the example, if a CBRA resource of type four-step RA is explicitly provided in the early TA configuration for obtaining the selected BWP for early TA, then UE 801 performs an RA of type four-step RA.

[0124] exist Figure 8 In the example, procedure 800 begins with operation 805. In operation 805, UE 801 sends a PRACH preamble using the CBRA RACH resources contained in the earlier TA configuration. UE 804 selects the SSB, and / or (if configured) the PRACH group, and / or the PRACH preamble index, and / or the PRACH timing according to the CBRA procedure.

[0125] In operation 810, non-serving cell 803 receives a PRACH preamble sent using the CBRA resources allocated to SpCell for early TA acquisition. Non-serving cell 803 may assign different RACH configurations (including RACH resources) to different serving cells. Non-serving cell 803 may identify the serving cell based on the received PRACH preamble. In operation 815, non-serving cell 803 sends the TA and RA-RNTI for the received PRACH preamble to the serving cell (SpCell 802).

[0126] During operation 820, for a RAR identified by the RA-RNTI, UE 801 listens to the PDCCH of serving cell 802 during the ra-ResponseWindow operation. If a valid downlink allocation for the RA-RNTI is received on the PDCCH, and the received TB is successfully decoded, and the RAR contains a MAC sub-PDU with a RAPID corresponding to the preamble index of the transmission, then UE 801 considers the RAR to have been successfully received.

[0127] In operation 825, if the RAR is successfully received, UE 801 processes the TA, UL grant, and TC-RNTI contained in the MAC RAR. UE 801 stores the TA. UE 801 processes the UL grant received in the RAR and instructs the lower layer to use it for Msg3 transmission. UE 801 sets the temporary _C-RNTI (TEMPORARY_C-RNTI) to the value of the TC-RNTI received in the RAR.

[0128] In operation 830, UE 801 uses a UL authorization with a C-RNTI included in the PUSCH to send Msg3 to serving cell 802, where the C-RNTI is for non-serving cell 802. The C-RNTI associated with non-serving cell 802 can be assigned to UE 801, and this identifier is provided in the early TA configuration or in the configuration for non-serving cell 802 (e.g., RRC reconfiguration). Figure 5 Operation 505).

[0129] In operation 835, once Msg3 is sent to serving cell 802, UE 801 listens to the serving cell's PDCCH during the ra-ResponseWindow operation, regardless of whether a measurement gap may occur.

[0130] In operation 840, in one example, if the CBRA is initiated for early TA acquisition and Msg3 contains the C-RNTI of the non-serving cell, and if the PDCCH received in operation 835 addresses the C-RNTI, then UE 801 considers the contention resolution successful, stops the ra-ContentionResolutionTimer, discards the TEMPORARY_C-RNTI, and considers the CBRA procedure for early TA acquisition to have been successfully completed.

[0131] In another example, in operation 840, if Msg3 contains a CCCH SDU, and the PDCCH received in operation 835 addresses its TEMPORARY_C-RNTI, and if the MAC PDU is successfully decoded, then UE 801 stops the ra-ContentionResolutionTimer. In operation 840, if the MAC PDU contains an Early TA Contention Resolution Identifier (MAC CE) (e.g., ...), ... Figure 7 As shown in the diagram, if the UE contention resolution identifier in the MAC CE matches the CCCH SDU sent in Msg3, and the C-RNTI in the MAC CE matches the C-RNTI value sent in Msg3, then UE 801 considers the contention resolution successful, discards the TEMPORARY_C-RNTI, and considers the CBRA procedure for early TA acquisition to have been successfully completed. Alternatively, in operation 840, if the MAC PDU contains the UE contention resolution identifier MAC CE, and the UE contention resolution identifier in the MAC CE matches the CCCH SDU sent in Msg3, and if the MAC PDU also contains a C-RNTI MAC CE that matches the C-RNTI value sent in Msg3, then UE 801 considers the contention resolution successful, discards the TEMPORARY_C-RNTI, and considers the CBRA procedure for early TA acquisition to have been successfully completed. An example of the early TA contention resolution identifier MAC CE is shown below. Figure 7 As shown.

[0132] although Figure 8 An exemplary UE procedure 800 for a four-step CBRA with serving cell involvement for early TA acquisition is shown, but it is possible to modify... Figure 8Various changes were made. For example, although it was shown as a series of steps, Figure 8 The various steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0133] Figure 9 An exemplary UE procedure 900 for a two-step CBRA for early TA acquisition with no serving cell participation, according to an embodiment of this disclosure, is shown. Figure 9 The illustrated process examples are for illustrative purposes only. Figure 9 One or more components shown may be implemented as dedicated circuitry configured to perform the functions described, or one or more components may be implemented by one or more processors executing instructions to perform the functions. Other embodiments of the two-step CBRA UE procedure involving no-serving cell participation for early TA acquisition may be used without departing from the scope of this disclosure.

[0134] exist Figure 9 In the example, if a two-step RA type CBRA resource is explicitly provided in the early TA configuration for obtaining the selected BWP for early TA, then UE 901 performs a two-step RA type RA.

[0135] exist Figure 9 In the example, procedure 900 begins with operation 905. In operations 905 and 910, UE 901 performs a CBRA with a two-step RA type. UE 901 sends the MsgA PRACH preamble and MsgA PUSCH using the CBRA RACH resources contained in the earlier TA configuration. UE 901 selects the SSB, and / or (if configured) the PRACH preamble group, and / or the PRACH preamble index, and / or the PRACH timing and / or the PUSCH timing according to the CBRA procedure.

[0136] In operations 915 and 920, if MsgA is sent in the two-step CBRA, then for the RAR identified by MSGB-RNTI, UE 901 listens (if configured) for the PDCCH of the non-serving cell during the msgB-ResponseWindow run.

[0137] In one scenario, if a notification of receiving a PDCCH transmission from the serving cell or (if configured) a PDCCH from a non-serving cell is received from a lower layer, and if MsgA does not contain a C-RNTI MAC CE, if a valid downlink allocation for the MSGB-RNTI is received on the PDCCH, and the received TB is successfully decoded, and if MsgB contains a Successful Random Access Response (successRAR) MAC sub-PDU, and if MSGA contains a CCCH SDU, and the UE contention resolution identifier in the successRAR MAC sub-PDU matches the CCCH SDU, and if the C-RNTI in the successRAR MAC sub-PDU matches the C-RNTI of the non-serving cell configured in the early TA configuration or in the configuration associated with the non-serving cell, then UE 901 stops the msgB-ResponseWindow, considers the RAR reception successful, and considers the two-step CBRA for early TA acquisition successful. UE 901 processes the TA in the successRAR. UE 901 considers the TA in the successRAR to be for non-serving cell 903. In another example, if the successRAR contains a TAGID that matches the TAG ID of the configuration associated with non-serving cell 903 in an earlier TA configuration, UE 901 considers the TA to be for non-serving cell 903. If the TA for non-serving cell 903 is obtained, UE 901 applies that TA to that non-serving cell (i.e., non-serving cell 903) and (if any) other cells (e.g., primary cell 902) that belong to the TAG configured in the earlier TA configuration associated with the candidate cell (i.e., non-serving cell 903). UE 901 starts or restarts the time alignment timer for that TAG and sets the timer duration to the value indicated by the timerAlignmentTimer parameter in the earlier TA configuration for non-serving cell 903. If the ra-ContentionResolutionTimer expires, UE 901 discards the TEMPORARY_C-RNTI, deeming the contention resolution unsuccessful, and discards the TA in the RAR. UE 901 may ignore the TPC, PUCCH resource indicator, ChannelAccess-CPext (if indicated), and HAPQ feedback timing indicator received in successRAR.

[0138] In another scenario, if a reception notification for a transmission of the serving cell's PDCCH or (if configured) the non-serving cell 903's PDCCH is received from a lower layer, and if MsgA does not contain a C-RNTI MAC CE, if a valid downlink allocation for the MSGB-RNTI is received on the PDCCH, and the received TB is successfully decoded, and if MsgB contains a fallback RAR MAC sub-PDU, and if the RAPID in the MAC sub-PDU matches the preamble index of the transmission, then UE 901 considers the RAR reception successful. If the RAR reception is successful, UE 901 processes the TA, UL grant, and TC-RNTI contained in the MAC RAR. UE 901 stores the TA. UE 901 processes the UL grant received in the RAR and instructs it to the lower layer for use in the Msg3 transmission. UE 901 sets TEMPORARY_C-RNTI to the value of the TC-RNTI received in the RAR. UE 901 then... Figure 6 The operations described in operations 620, 625, and 630 correspond to operations 925, 930, and 935 to perform a four-step rollback CBRA.

[0139] In another embodiment of the two-step CBRA, UE 901 can also perform operations 915-935 to the serving cell, and the UE behavior is the same. However, after sending MsgA to the non-serving cell (i.e., SpCell 902), for the RAR identified by MSGB-RNTI, UE 901 listens to the PDCCH of the serving cell 902 during the msgB-ResponseWindow operation, and receives the successful RAR or fallback RAR from the serving cell 902 in MsgB. If a fallback RAR is received, UE 901 then... Figure 8 The operations described in operations 830, 835, and 840 correspond to operations 925, 930, and 935 to perform a four-step rollback CBRA.

[0140] although Figure 9 An exemplary UE procedure 900 for a two-step CBRA for early TA acquisition without serving cell involvement is shown, but it is applicable to… Figure 9 Various changes were made. For example, although it was shown as a series of steps, Figure 9 The various steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0141] Figure 10 An exemplary method 1000 for early TA acquisition initiated by a UE according to an embodiment of this disclosure is shown. Figure 10 The method embodiments shown are for illustrative purposes only. Figure 10One or more components shown may be implemented as dedicated circuitry configured to perform the function, or one or more components may be implemented by one or more processors executing instructions to perform the function. Other embodiments of the UE-initiated early TA acquisition method may be used without departing from the scope of this disclosure.

[0142] exist Figure 10 In the example, method 1000 begins with step 1002. In step 1002, such as Figure 1 In step 1004, the UE 116 receives an early TA configuration containing early TA RA resources for the candidate cell in CLTM. In step 1006, the UE sends a PRACH preamble to the candidate cell on the early TA RA resources. In step 1007, the UE receives a message containing the current TA for the candidate cell. In step 1008, the UE applies the current TA to the candidate cell. Finally, in step 1010, the UE initiates the TAT for the candidate cell.

[0143] although Figure 10 An exemplary method 1000 for early TA acquisition initiated by the UE is shown, but it can be modified for... Figure 10 Various changes were made. For example, although it was shown as a series of steps, Figure 10 The various steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0144] Any of the above variant embodiments can be used independently or in combination with at least one other variant embodiment. The flowcharts above illustrate example methods that can be implemented according to the principles of this disclosure, and various changes can be made to the methods shown in the flowcharts herein. For example, although shown as a series of steps, the various steps in each figure may overlap, occur in parallel, occur in different orders, or occur multiple times. In another example, steps may be omitted or replaced with other steps.

[0145] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications will be apparent to those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims. Nothing described herein should 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-protected subject matter is defined by the claims.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: Receive configuration information from the base station of the serving cell for configuring random access resources acquired by early timing advance TA on the candidate cell; Perform the early TA acquisition process for the candidate cell; Receive from the base station a Media Access Control (MAC) control element (CE) associated with cell handover for L1 / L2-triggered mobility LTM; as well as Based on the MAC CE associated with the cell handover for L1 / L2 triggered LTM, a cell handover to the target cell is performed. The configuration information used for early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

2. The method according to claim 1, in, For contention-free random access (CFRA), the terminal is provided with at least one of the following: information about the number of synchronization signal blocks (SSBs) for each physical random access channel (PRACH) timing, information about the SSB index, information about the random access RA preamble index, or information about the PRACH mask index.

3. The method according to claim 1, in, The early TA acquisition process includes sending a random access preamble based on CFRA.

4. The method according to claim 1, in, If the timing advance time (TA) of the target cell is obtained based on the MAC CE, the TA is applied to the terminal, and a time alignment timer for the TA is started. In cases where the MAC CE fails to acquire the TA of the target cell, random access is performed on the target cell based on CFRA resources.

5. A method performed by a base station providing services to a terminal in a wireless communication system, the method comprising: Send configuration information to the terminal for configuring random access resources for early timing advance TA acquisition on candidate cells; as well as Based on the early TA acquisition procedure performed for the candidate cell, a Media Access Control (MAC) control element (CE) associated with cell handover for L1 / L2-triggered Mobility LTM is sent to the terminal. The cell handover to the target cell is performed based on the MAC CE associated with the LTM cell handover triggered for L1 / L2, and The configuration information used for early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

6. The method according to claim 5, in, For contention-free random access (CFRA), the terminal is provided with at least one of the following: information about the number of synchronization signal blocks (SSBs) for each physical random access channel (PRACH) timing, information about the SSB index, information about the random access RA preamble index, or information about the PRACH mask index.

7. The method according to claim 5, in, The early TA acquisition process includes sending a random access preamble based on CFRA.

8. The method according to claim 5, in, If the timing advance time (TA) of the target cell is obtained based on the MAC CE, the TA is applied to the terminal, and a time alignment timer for the TA is started. In cases where the MAC CE fails to acquire the TA of the target cell, random access is performed on the target cell based on CFRA resources.

9. A terminal in a wireless communication system, the terminal comprising: transceiver; as well as At least one processor, configured as follows: Receive configuration information from the base station of the serving cell for configuring random access resources acquired in the early timing advance TA on the candidate cell. Perform the early TA acquisition process for the candidate cell. Receive from the base station a Media Access Control (MAC) control element (CE) associated with cell handover for L1 / L2-triggered mobility LTM, and Based on the MAC CE associated with the cell handover for L1 / L2 triggered LTM, a cell handover to the target cell is performed. The configuration information used for early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

10. The terminal according to claim 9, in, For contention-free random access (CFRA), the terminal is provided with at least one of the following: information about the number of synchronization signal blocks (SSBs) for each physical random access channel (PRACH) timing, information about the SSB index, information about the random access RA preamble index, or information about the PRACH mask index.

11. The terminal according to claim 9, in, The early TA acquisition process includes sending a random access preamble based on CFRA.

12. The terminal according to claim 9, in, If the timing advance time (TA) of the target cell is obtained based on the MAC CE, the TA is applied to the terminal, and a time alignment timer for the TA is started. In cases where the MAC CE fails to acquire the TA of the target cell, random access is performed on the target cell based on CFRA resources.

13. A base station providing services to terminals in a wireless communication system, the base station comprising: transceiver; as well as At least one processor, configured as follows: Send configuration information to the terminal for configuring random access resources for early timing advance TA acquisition on candidate cells, and Based on the early TA acquisition procedure performed for the candidate cell, a Media Access Control (MAC) control element (CE) associated with cell handover for L1 / L2-triggered Mobility LTM is sent to the terminal. The cell handover to the target cell is performed based on the MAC CE associated with the LTM cell handover triggered for L1 / L2, and The configuration information used for early TA acquisition includes information about random access channel resources, uplink configuration for the carrier, and information about the bandwidth portion (BWP).

14. The base station according to claim 13, in, For contention-free random access (CFRA), the terminal is provided with at least one of the following: information about the number of synchronization signal blocks (SSBs) for each physical random access channel (PRACH) timing, information about the SSB index, information about the random access RA preamble index, or information about the PRACH mask index.

15. The base station according to claim 13, in, The early TA acquisition process includes sending a random access preamble based on CFRA. Specifically, when the timing advance time (TA) of the target cell is obtained based on the MAC CE, the TA is applied to the terminal, and a time alignment timer for the TA is started. In cases where the MAC CE fails to acquire the TA of the target cell, random access is performed on the target cell based on CFRA resources.

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