Methods and apparatuses for improvement and related to rach-less timing advance management

Abstract

This disclosure provides a method or apparatus for RACH-free timing advance management, wherein the method performed by a terminal includes: receiving from a first base station a first message including information about RACH-free handover; and sending a second message to a second base station for completing the handover process based on the RACH-free handover information, wherein RACH-free handover in frequency range 1 (FR1)-FR2 is not supported, and wherein the RACH-free handover information includes at least one of information about the beam of the physical downlink control channel (PDCCH) used by the terminal in the target cell for monitoring initial uplink transmission and information about the timing advance value used by the terminal for handover.

Description

Technical Field

[0001] This disclosure relates to the operation of base stations, user equipment, and core networks in mobile communication systems. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in "sub-6GHz" bands such as 3.5GHz, but also in "above 6GHz" bands, including 28GHz and 39GHz, known as millimeter waves (mmWave). Furthermore, 6G mobile communication technology (referred to as Beyond 5G systems) is being considered in terahertz bands (e.g., the 95GHz to 3THz band) to achieve transmission rates 50 times faster than 5G and ultra-low latency one-tenth that of 5G.

[0003] In the early stages of 5G mobile communication technology development, to support services and meet performance requirements related to enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), standardization has been underway for the following: beamforming and massive MIMO to mitigate radio wave path loss and increase radio wave transmission distance in millimeter waves; support for basic parameter sets (e.g., operating 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; definition and operation of the Bandwidth Part (BWP); new channel coding methods, such as low-density parity-check (LDPC) codes for large-scale data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing to provide dedicated networks for specific services.

[0004] Currently, given the services that 5G mobile communication technology will support, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology, and physical layer standardization already exists for technologies such as: Vehicle-to-everything (V2X), used to assist autonomous vehicles in determining driving based on information sent by the vehicle about its location and status, and to enhance user convenience; New Radio Unlicensed (NR-U), for system operation in compliance with various regulatory requirements in unlicensed frequency bands; NR UE power saving; Non-Terrestrial Network (NTN), which is UE-satellite direct communication used to provide coverage in areas where communication with terrestrial networks is unavailable; and positioning.

[0005] Furthermore, standardization is underway in air interface architecture / protocols for technologies such as: Industrial Internet of Things (IIoT) to support new services through interoperability and convergence with other industries; Integrated Access and Backhaul (IAB) to provide nodes for network service area extension by supporting radio 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 to simplify random access procedures (2-step RACH for NR). Standardization is also underway in system architecture / services for: 5G baseline architecture (e.g., service-based architecture or service-based interface) to combine Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies; and Mobile Edge Computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will connect to the communication network. Accordingly, enhanced functionality and performance of 5G mobile communication systems, as well as the integrated operation of connected devices, are expected to be necessary. To this end, new research is planned related to the following: extended reality (XR) for effectively supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), etc.; improving 5G performance and reducing complexity by leveraging artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communication.

[0007] Furthermore, this development of 5G mobile communication systems will not only serve as the foundation for developing new waveforms for providing terahertz band coverage for 6G mobile communication technologies, multi-antenna transmission technologies (such as full-dimensional MIMO (FD-MIMO), array antennas, and massive MIMO), metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS), but also as the foundation for developing full-duplex technologies to improve the frequency efficiency of 6G mobile communication technologies and improve system networks, AI-based communication technologies to implement system optimization by leveraging satellites and artificial intelligence (AI) from the design stage and internalizing end-to-end AI support capabilities, and next-generation distributed computing technologies to implement services with complexity exceeding the limits of UE operational capabilities by utilizing ultra-high-performance communication and computing resources. Summary of the Invention

[0008] Technical issues

[0009] This disclosure provides a method and apparatus for RACH-free timing advance management.

[0010] The technical subject matter of this disclosure may not be limited to the above-mentioned technical subject matter, and other technical subject matter not mentioned will be clearly understood by those skilled in the art from the following description.

[0011] Problem Solution

[0012] To address the aforementioned issues, a method performed by a terminal in a wireless communication system according to an embodiment of this disclosure may include: receiving from a first base station a first message including information about no random access channel (RACH) handover; and, based on the information about no RACH handover, sending to a second base station a second message for completing the handover process, wherein no RACH handover in frequency range 1 (FR1)-FR2 is not supported.

[0013] In an embodiment, the information regarding RACH-free handover includes at least one of information about the beam of the Physical Downlink Control Channel (PDCCH) used by the terminal to monitor the initial uplink transmission in the target cell and information about the timing advance value used by the terminal for handover.

[0014] In one embodiment, the first message includes information about uplink authorization for sending the first message or information for monitoring uplink authorization from a second base station.

[0015] In one embodiment, sending the second message includes: receiving a physical downlink control channel (PDCCH) for uplink authorization from the second base station based on information regarding no RACH handover, provided that the first message includes information for monitoring uplink authorization from the second base station; and sending the second message to the second base station based on the uplink authorization.

[0016] In one embodiment, the first message includes a message for modifying the Radio Resource Control (RRC) connection.

[0017] To address the aforementioned problems, a method performed by a first base station in a wireless communication system according to an embodiment of this disclosure may include: sending a handover request message to a second base station; receiving a handover request confirmation message from the second base station; and sending a first message to a terminal including information about handover without a random access channel (RACH), wherein a second message for completing the handover process is sent to the second base station based on the information about handover without RACH, and wherein handover without RACH in frequency range 1 (FR1)-FR2 is not supported.

[0018] To address the aforementioned issues, a terminal in a wireless communication system according to an embodiment of this disclosure may include: a transceiver; and a controller coupled to the transceiver and configured to: receive from a first base station a first message including information about no random access channel (RACH) handover; and based on the information about no RACH handover, send to a second base station a second message for completing the handover process, wherein no RACH handover in frequency range 1 (FR1)-FR2 is not supported.

[0019] To address the aforementioned issues, a first base station in a wireless communication system according to an embodiment of this disclosure may include: a transceiver; and a controller coupled to the transceiver and configured to: send a handover request message to a second base station; receive a handover request confirmation message from the second base station; and send a first message to a terminal including information about handover without a random access channel (RACH), wherein a second message for completing the handover process is sent to the second base station based on the information about handover without RACH, and wherein handover without RACH in frequency range 1 (FR1)-FR2 is not supported.

[0020] Beneficial effects of the invention

[0021] This disclosure provides a method and apparatus for RACH-free timing advance management.

[0022] The beneficial effects that can be obtained from this disclosure are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art to which this disclosure pertains from the following description. Attached Figure Description

[0023] Figure 1 a illustrates a handover without RACH, where the UE is configured with uplink grant.

[0024] Figure 1 b illustrates a scenario where the UE is configured to monitor the PDCCH of the target cell.

[0025] Figure 2 The SCG addition process is shown (from the UE's perspective).

[0026] Figure 3 The process of adding EN-DC SCG is shown.

[0027] Figure 4 a shows the timing advance from the cell with SCS=30kHz used in a cell with SCS=15kHz, and the timing advance command is used later.

[0028] Figure 4 b shows the TA used at SCS=30kHz rounded down to the value used at SCS=15kHz.

[0029] Figure 5a The SCG setup using EN-DC N_TA translation is shown.

[0030] Figure 5b The SCG setup using the N_TA conversion of NE-DC is shown.

[0031] Figure 6The configuration of a UE according to an embodiment of this disclosure is shown.

[0032] Figure 7 The configuration of a base station according to an embodiment of this disclosure is shown. Detailed Implementation

[0033] In describing this disclosure below, detailed descriptions of known functions or configurations incorporated herein will be omitted where it is determined that such description might unnecessarily obscure the subject matter of the disclosure. Embodiments of this disclosure will be described below with reference to the accompanying drawings.

[0034] The operating principles of this disclosure will be described in detail below with reference to the accompanying drawings. The terminology described below is defined with reference to the functions in this disclosure. These terms may vary depending on the user, the user's intention, or habits; therefore, the definitions of the terms should be based on the entire contents of this specification.

[0035] For the same reason, some elements may be exaggerated, omitted, or shown schematically in the accompanying drawings. Furthermore, the size of each element does not perfectly reflect its actual size. In the various drawings, the same or corresponding elements are given the same reference numerals.

[0036] The advantages and features of this disclosure, as well as the ways in which these advantages and features are realized, will become apparent from the embodiments described in detail below with reference to the accompanying drawings. However, this disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose this disclosure and to inform those skilled in the art of its scope, and this disclosure is limited only by the scope of the appended claims. Throughout this disclosure, the same or similar reference numerals denote the same or similar elements.

[0037] In this document, it will be understood that each box in a flowchart illustration, and combinations of boxes in a flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create components for implementing the functions specified in one or more boxes of the flowchart. These computer program instructions can also be stored in a computer-usable or computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-usable or computer-readable storage medium produce an article of writing, including instruction components that implement the functions specified in one or more boxes of the flowchart. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus, thereby producing a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more boxes of the flowchart.

[0038] Furthermore, each box in a flowchart can represent a module, code segment, or code section, including one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions mentioned in the boxes may not appear in a specific order. For example, two boxes shown consecutively may actually execute substantially simultaneously, or these boxes may sometimes execute in reverse order, depending on the functions involved.

[0039] As used in embodiments of this disclosure, the term "cell" refers to a software element or hardware element, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), and a "cell" can perform certain functions. However, "cell" does not always have a meaning limited to software or hardware. A "cell" can be configured to be stored in addressable storage media or to execute one or more processors. Thus, a "cell" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and parameters. Elements and functions provided by a "cell" can be combined into a smaller number of elements or "cells," or divided into a larger number of elements or "cells." Furthermore, elements and "cells" can be implemented as replicas of one or more CPUs within a device or secure multimedia card.

[0040] The specific terminology used in the following description is merely for the purpose of understanding this disclosure, and other types of terminology may be used without departing from the technical spirit of this disclosure.

[0041] As used herein, for ease of description, terms relating to network entities, messages, identification information, etc., are used illustratively. Therefore, this disclosure is not limited to the terms described below, and other terms relating to subjects with equivalent technical meanings may also be used.

[0042] In the following description, for ease of description, the terms and names defined in the 5G system standard will be used to describe this disclosure, but this disclosure is not limited to these terms and names and can be applied in the same way to systems conforming to other standards.

[0043] The Random Access Channel (RACH) is a crucial component of wireless communication systems, including 5G (or New Radio), 4G (or Long Term Evolution LTE), and even 3G. The RACH plays a vital role in establishing the initial connection (initial access) between devices and the network. It is also important when handing over a User Equipment (UE) from one cell to another.

[0044] RACH-free is a handover method introduced in E-UTRAN version 14. This method allows the UE to skip performing random access during handover. This is to improve handover latency in certain situations.

[0045] In certain cases related to timing advance (TA), RACH-free execution is possible:

[0046] When the TA to the target cell is zero

[0047] When the TA to the target cell equals the TA to the source cell

[0048] Figure 1 a illustrates a handover without RACH, where the UE is configured with uplink grant; and Figure 1 b illustrates a scenario where the UE is configured to monitor the PDCCH of the target cell.

[0049] RACH-free can be considered to include two different approaches:

[0050] - Continuous uplink grant is configured for the UE to send a first message after handover, which is RRCReconfigurationComplete and optionally any data. In this case, the UE is configured with uplink grant ( ul-Grant ), scheduling interval ( ul-SchedInterval ) and the number of opportunities to configure ( numberOfConfUL- Processes )

[0051] - The UE is scheduled to synchronize with the target cell without sending any messages to the target cell. Instead, the UE begins monitoring the PDCCH for the assignment from the target cell. The assignment can be for downlink PDSCH transmissions or UL authorization for the UE to send PUSCH.

[0052] The following fields are configured to indicate whether RACH is enabled:

[0053] targetTA

[0054] numberOfConfUL-Processes

[0055] ul-SchedInterval

[0056] ul-StartSubframe

[0057] ul-Grant

[0058] For the target TA, there are many options regarding what to apply in the target cell for timing advance. The UE can set N. TA =0 or N TA This is equivalent to another serving cell that the UE has already connected to, such as PCell or SCell.

[0059] The introduction of RACH-free access is not only for handover but also for establishing a secondary eNB (SeNB). The establishment of a SeNB is usually accomplished through a random access procedure.

[0060] Carrier aggregation (CA) is a key technology for modern cellular connectivity introduced for LTE in Rel-10. Natively implemented in the first 5G NR release, carrier aggregation is crucial for ensuring higher speeds.

[0061] As the name suggests, carrier aggregation allows a single base station (gNB) to aggregate multiple carriers. In addition to the primary cell (PCell or PSCell) to which the UE makes an RRC connection, the gNB also configures a secondary cell (SCell). Each carrier is sometimes referred to as a component carrier.

[0062] Dual connectivity DC is another important technology introduced for LTE in Rel-12 and is natively implemented for 5G NR. Dual connectivity is implemented in several different ways, such as E-UTRAN-NR DC, NR-E-UTRAN DC, and NR DC. Dual connectivity allows a UE to connect to both the primary node (MN) and the secondary node (SN) simultaneously, i.e., two different gNBs.

[0063] In NR, the MN will have an associated primary cell group (MCG), and the SN will have an associated secondary cell group (SCG), allowing dual connectivity and carrier aggregation to coexist. A cell group refers to either an MCG or an SCG. A primary cell (PCell) is a non-secondary cell within an MCG, and a primary SCG cell (PSCell) is a non-secondary cell within an SCG. A special cell (SpCell) refers to either a PCell or a PSCell. These gNBs can be collocated or not, and each node can have multiple SCells, i.e., carriers. In 5G NR, a common use case is that the MN / MCG is located in frequency range 1 (FR1), and the SN / SCG is located in FR2.

[0064] Compared to carrier aggregation, in dual connectivity, the MN and SN will operate more independently, allowing the MN and SN to be configured for the UE, for example, to perform separate measurements in each cell group.

[0065] Figure 2 The SCG addition process is shown (from the UE's perspective).

[0066] SCG addition, also known as SN addition, SCG establishment, or DC establishment, is the process used to establish dual connectivity by adding another SCG. From the UE's perspective, the process of adding an SCG can be... Figure 2 I saw it in the middle.

[0067] Figure 2 The steps listed are as follows:

[0068] Step 1: First, make the decision to try to build an SCG.

[0069] Step 2: The MN initiates SCG addition by sending an S-Node Add Request to the SN. If the SN can accommodate the UE and the SCG role, the SN generates the SCG RRC configuration and replies with an S-Node Add Request Confirmation, which includes the RRC configuration of the SCG that the UE will apply.

[0070] Step 3: RRCReconfiguration is sent to the UE to configure the SCG. For NR SCG addition, mrdc-SecondaryCellGroupConfig is set to nr-SCG, and gNB includes the CellGroupConfig field.

[0071] Step 4: RRCReconfigurationComplete can be generated before or after random access has been performed on the SN.

[0072] Step 5: Perform random access on the SgNB.

[0073] The RRC message SCGFailureInformation is used to indicate to the MN that the UE has experienced a failure on the SCG link. For example, this could be due to a radio link failure, an SCG synchronization failure, or an SCG configuration failure. SCGFailureInformation contains the field FailureReportSCG, which may include the failure type, possible UE measurements, location information, previously visited cells, etc.

[0074] Figure 3 The process of adding EN-DC SCG is shown.

[0075] Combined with EN-DC SCG, Figure 3 The process of adding NR SCG from E-UTRAN MN from the UE's perspective is shown.

[0076] Figure 3 The steps listed are as follows:

[0077] Step 1: First, make the decision to try to build an SCG.

[0078] Step 2: The MN initiates SCG addition by sending an SGNB Add Request to the SN. If the SN can accommodate the UE and the SCG role, the SN generates the SCG RRC configuration and replies with an SGNB Add Request Confirmation, which includes the RRC configuration of the SCG that the UE will apply.

[0079] Step 3: RRCConnectionReconfiguration is sent to the UE to configure the SCG. For NR SCG addition, nr-SecondaryCellGroupConfig has a transparent NR RRC container containing the configuration to be used in the NR SCG.

[0080] Step 4: RRCReconfigurationComplete can be generated before or after random access has been performed on the SN.

[0081] Step 5: Perform random access on the SgNB.

[0082] It is meaningful to better understand how timing advance works in NR and LTE.

[0083] In LTE, the UE's full timing is advanced by T. TA Defined as [Mathematical Formula 1]:

[0084] [Mathematical Expression 1]

[0085]

[0086] The components are:

[0087] T s =Basic time unit 1 / (15000 x 2048) = 1 / 30720000

[0088] N TA =T A x 16

[0089] It is a non-terrestrial network NTN-specific

[0090] In NR, T is the complete and absolute timing advance of the UE. TA Defined as [Mathematical Expression 2]:

[0091] [Mathematical Expression 2]

[0092]

[0093] The components are:

[0094] T c The basic time unit of NR is 1 / (480x10). 3 x 4096) = 1 / 1966080000

[0095] N TA This refers to MAC-signalled timing advance, calculated as follows:

[0096] ○ Specifically, how to calculate timing advance when receiving a TA in a random access response.

[0097] ○ Receive T in the MAC CE at the scheduled advance time. A Time calculation

[0098] μ is the subcarrier spacing configuration, which can take values ​​of [0, 1, 2, 3, 4, 5, 6], corresponding to subcarrier spacing (SCS) of [15, 30, 60, 120, 240, 480, 960] kHz. Generally, the higher the frequency, the higher the subcarrier spacing.

[0099] It is specific to NTN

[0100] As can be seen from the above, in NR, N TA The granularity of the value changes with the subcarrier spacing. For example, for SCS=15kHz, the value that the timing advance change for the UE application is [value]. N TA =[..., -4096, -3072, -2048, -1024, 0, 1024, 2048, ...]. For SCS=60kHz, the UE applied value... N TA =[...,-1024,-768,-512,-256,0,256,512,768,1024,...].

[0101] The difference between LTE and NR is that in LTE, the SCS is always the same, while in NR, the basic time unit is much smaller.

[0102] When performing a RACH-free handover between different cells or establishing a new cell using RACH-free LTE, the UE can apply the same timing advance as the source cell in the target cell, or use a timing advance equal to zero. Applying the same timing advance is specified as reusing the same N. TA .

[0103] In NR, the timing advance adjustment changes with the subcarrier spacing (which is typically configured to be frequency-dependent).

[0104] This can cause problems when performing RACH-free handovers between different cells on different frequencies or when establishing another cell on another frequency or using a Radio Access Technology (RAT).

[0105] For LTE, in addition to being introduced for mobility purposes, Rel-14 also introduced the option to perform SN addition using no RACH.

[0106] Since RACH-free technology was introduced for NR for mobility purposes, it would also be beneficial to introduce RACH-free technology for SN. However, the number and types of dual-connectivity scenarios are greater in 5G compared to LTE. For example, the following are different:

[0107] Compared to LTE, NR has a much wider frequency band, which will affect the way dual connectivity works.

[0108] In addition to NR-DC (where both branches (legs) in DC are NR), there are also EN-DC and NE DC cases.

[0109] As an example of the problem, LTE without RACH has several options regarding how to handle the timing advance of the target cell / target SN. One option is to use N in the target cell. TA =0, using one of the already established cells (such as PCell or any SCell) in the target cell. TA However, if LTE cells are used in NR, then... TA Then it is necessary to ensure N TA It can be truly applied to NR cells.

[0110] According to the present invention, an apparatus and method are provided according to the appended claims. Other features of the invention will become apparent from the dependent claims and the following description.

[0111] According to a first aspect of the present invention, a method for operating a telecommunications network to perform a RACH-free handover between a source cell and a target cell is provided, comprising the following steps:

[0112] a) Determine whether to configure an operable user equipment (UE) for RACH-free handover based on predetermined conditions;

[0113] b) If this is determined, a handover command is sent to the UE to perform a RACH-free handover, wherein the predetermined condition is one of the following:

[0114] (i) The target cell is not on a different subcarrier spacing (SCS) compared to the source cell;

[0115] (ii) The target cell is not on a different frequency than the source cell;

[0116] (iii) Compared with the source cell, the target cell is on a different frequency and is pre-configured to zero;

[0117] (iv) The target cell is on a different SCS than the source cell, and is pre-configured to zero at specific times; and

[0118] (v) The target cell is on a different SCS than the source cell, and the timing advance is adjusted based on the SCS in the target and source cells.

[0119] In this embodiment, the switching command includes a configuration for advance timing, which includes one of the following:

[0120] If the target cell is on a different SCS than the source cell, the timing is pre-configured to zero;

[0121] If the target cell operates on a different frequency than the source cell, the timing is pre-configured to zero; and

[0122] If the target cell's SCS is adjusted based on the difference between the target cell's SCS and the source cell's SCS, then the timing advance is configured to be the same as the target cell's timing advance.

[0123] In an embodiment, if the predetermined condition is (v) that the target cell is on a different SCS compared to the source cell, and the timing advance is adjusted based on the SCS in the target cell and the source cell, then the result is rounded down to the nearest N. TA Or round up to the nearest N. TA To make adjustments.

[0124] In an embodiment, if the timing advance is adjusted by rounding down, the minimum value is assigned using a round-down function.

[0125] In this embodiment, if the timing advance is adjusted by rounding up, the maximum value is assigned using the round-up function.

[0126] In an embodiment, if the predetermined condition is (v) that the target cell is on a different SCS compared to the source cell, and the timing advance is adjusted based on the SCS in the target cell and the source cell, then

[0127] In this embodiment, rounding is performed if one or more of the following:

[0128] The target cell's SCS is smaller than the source cell's SCS;

[0129] The target cell frequency is lower than the source cell frequency;

[0130] Switching refers to switching between frequencies.

[0131] In this embodiment, when the target cell frequency is lower than the source cell frequency, the handover is from frequency range 2 FR2 to FR1.

[0132] In this embodiment, the explicit instruction to perform rounding is included in a no-RACH configuration message.

[0133] In some instances, regardless of any determination, a RACH-free handover may not be performed. Such instances include handovers between SCSs or between frequencies.

[0134] In this embodiment, RACH-free handover or RACH-free establishment between SCSs or between frequencies can only be performed when the timing advance is configured as 0.

[0135] According to a second aspect of the invention, a method is provided for operating a user equipment (UE) arranged for RACH-free handover, wherein the UE has been configured by an operatively connected telecommunications network for conditional RACH-free handover.

[0136] In this embodiment, a conditional RACH-free handover is performed based on one of the following:

[0137] (i) The target cell is not on a different subcarrier spacing (SCS) compared to the source cell;

[0138] (ii) The target cell is not on a different frequency than the source cell;

[0139] (iii) Compared with the source cell, the target cell is on a different frequency and is pre-configured to zero;

[0140] (iv) The target cell is on a different SCS than the source cell, and is pre-configured to zero at specific times; and

[0141] (v) The target cell is on a different SCS than the source cell, and the timing advance is adjusted based on the SCS in the target and source cells.

[0142] According to a third aspect of the invention, a telecommunications network is provided that is arranged to perform the method of the first aspect.

[0143] According to a fourth aspect of the invention, a user equipment is provided that is arranged to perform the method of the second aspect.

[0144] The core idea of ​​this invention is: when the signaling notifies the UE that it needs to use the timing advance of the source cell in the target cell, a method for managing timing advance during RACH handover or RACH cell establishment is provided.

[0145] The example uses a term called configured or pre-configured uplink grant to describe RACH-free handover, but this is only one option. Another option is to configure the UE to monitor the PDCCH, and then the target eNB sends a PDCCH containing the UL grant.

[0146] The embodiments are primarily described using gNB (4G E-UTRAN), but can also be applied to ENB or NG-RAN (5G NR). The embodiments can also be applied to eMTC / LTE-M UE, 5G NR UE, or E-UTRAN UE.

[0147] When performing a RACH-less handover or RACH-less establishment, the source cell can be a PCell, PSCell, or SpCell. Similarly, the target cell can become a PCell, PSCell, or SpCell.

[0148] Although several preferred embodiments of the invention have been shown and described, those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the invention as defined by the appended claims.

[0149] To better understand the present invention and to illustrate how embodiments of the invention can be implemented, reference will now be made to the accompanying drawings by way of example only, wherein:

[0150] Figure 1 a shows a RACH-less handover with uplink authorization configured;

[0151] Figure 1 b illustrates a RACH-free handover in which the UE is configured to monitor the PDCCH of the target cell;

[0152] Figure 2 The process of adding SCG is shown;

[0153] Figure 3 The EN-DC SCG addition process is shown;

[0154] Figure 4 a shows the timing advance from the cell with SCS=30kHz used in a cell with SCS=15kHz, and the timing advance command is used later;

[0155] Figure 4 b shows the TA that will be used at SCS=30kHz rounded down to the value that will be used at SCS=15kHz;

[0156] Figure 5a The SCG setup using the N_TA conversion of EN-DC is shown; and

[0157] Figure 5b The SCG setup using the N_TA conversion of NE-DC is shown.

[0158] To perform RACH-free handover or RACH-free SgNB addition, some management of timing is required in advance. For example, when performing a RACH-free handover from a first cell to a second cell with a lower SCS, the N used in the first cell... TA This may not apply to the second cell. This is because N TA Possibly due to the configurable N of the second cell TA Between values.

[0159] For example, N from the first cell with SCS=60kHz TA The value can be 3 x 16 x 64 / 2 3 = 384, while in the second cell, NTA The particle size is a multiple of 1024.

[0160] Therefore, in one embodiment of the present invention, when performing inter-SCS no-RACH handover, inter-frequency no-RACH handover, or no-RACH establishment, the N used from the first cell... TA Round up or down to a value consistent with the cell's specific SCS.

[0161] If rounding down, use the floor function, similar to [Mathematical Expression 3] below:

[0162] [Mathematical Expression 3]

[0163]

[0164] If you want to round up, use the floor function, similar to [Mathematical Expression 4] below:

[0165] [Mathematical Expression 4]

[0166]

[0167] Above, N is applied to the target cell when calculating the complete timing advance. TA . This is the value used in the source cell.

[0168] The conditions to be applied above can be one or a combination of the following:

[0169] The target cell SCS is smaller than the source cell SCS.

[0170] The target cell frequency is less than the source cell frequency.

[0171] For example, it could be FR2 to FR1.

[0172] The condition could be that it involves switching between frequencies.

[0173] The above can be applied through implicit or explicit indication. Implicitly, the above applies when one of the conditions is met: that is, when the UE applies the source TA in the target cell during a no-RACH handover and the target cell has a lower SCS than the source cell. Explicitly, bits in the no-RACH configuration can indicate that rounding should be performed. In the improved version, two bits are used: 00 indicates no rounding, 01 indicates rounding up, 10 indicates rounding down, and 11 indicates unused.

[0174] In one embodiment of the invention, there are restrictions on when RACH-free handover can be performed. For example, RACH-free handover between SCSs or between frequencies (e.g., between FR1 and FR2) may not be performed. For example, RACH-free handover or RACH-free establishment between SCSs or frequencies can only be performed when TA=0 is configured. This can be seen in Example #1. In a further improvement, RACH-free handover to a lower SCS can only be performed using TA=0, or RACH-free handover or RACH-free establishment can only be performed when SCS values ​​are adjacent, for example, 120kHz->60kHz, 60kHz->30kHz, 30kHz->15kHz. In another improvement, only when... and A RACH-free switch or RACH-free setup can only be performed when the difference between the two values ​​is below a certain predefined or configurable threshold.

[0175] In one embodiment of the invention, the same method can be used when performing a handover from a first cell (where the UE is configured to operate on the first cell with a bandwidth portion (BWP) having a specific SCS) to a second cell having an SCS different from that in the first cell. This means that even if the first and second cells can operate with the same SCS, the UE can be specifically configured with a BWP having an SCS different from either of the two cells. In other words, even if the common configuration indicates that the cells have the same SCS, an SCS change can still occur.

[0176] For example, some of the above may indicate that no RACH handover or SCG establishment may only be performed within the same frequency range (FR1->FR1, FR2->FR2, FR2-1->FR2-1, etc.).

[0177] In the above, it may be necessary to round to the nearest multiple of the timing advance, i.e. Where μ is the SCS number. This can be found in... Figure 4 As seen in a, it shows the timing advance from the cell with SCS=30kHz used in a cell with SCS=15kHz, and the timing advance command is used later.

[0178] In another embodiment of the invention, whether the UE should round up / down to the nearest multiple of the timing advance can be configurable. This can be achieved in... Figure 4 As seen in b, UE is rounded down. More specifically, TA is rounded down from the value used in SCS=30kHz to the value used in SCS=15kHz.

[0179] The following content pertains to EN-DC and NE-DC RACH-free SCG establishment. Since absolute timing advance is based on NR and LTE... TA Defined by, but N is established in each case TA The steps involved are different, so one feature of this embodiment of the invention relates to N when performing EN-DC and NE-DC without RACH SCG establishment. TA The conversion.

[0180] In one embodiment of the invention, when EN-DC no-RACH SCG establishment is performed, and the MN eNB signaling notifies the target TA that it should rely on an already serving cell, there is a transition from LTE to NR N. TA Conversion:

[0181] [Mathematical Expression 5]

[0182]

[0183] Therefore, the N applied from the source E-UTRAN cell to the target NR cell TA The target is E-UTRAN N TA Multiply by a factor that is the difference between the LTE and NR basic time units.

[0184] For example, the conditions for applying the above transformation can be that one or more of the following conditions are true:

[0185] The target cell or SN is NR

[0186] The source cell or MN is E-UTRAN

[0187] LTE RRC message RRCConnectionReconfiguration middle nr-SecondaryCellGroupConfig Part of it.

[0188] Similarly, when performing NE-DC no-RACH SCG establishment, and the MN gNB signaling notifies the target TA that it should rely on an already serving cell, there is a transition from NR to LTE N. TA Conversion:

[0189] [Mathematical Expression 6]

[0190]

[0191] For example, the conditions for applying the above transformation can be that one or more of the following conditions are true:

[0192] The target cell or SN is E-UTRAN

[0193] The source cell or MN is NR

[0194] Signaling notification as rach-SkipSCG part

[0195] NR RRC message RRCReconfiguration middle eutran-scg Part of it.

[0196] The above will apply regardless of whether the network signaling notifies the UE to use the serving cell (i.e., PCell or any SCell) from which it is scheduled in advance.

[0197] These two examples may later be referred to as "Example #2" and "Example #3" in this application, as well as in Figure 5a and 5b As seen in the diagram, SCG creation using N_TA conversion with EN-DC and SCG creation using N_TA conversion with NE-DC are shown respectively.

[0198] Since there are many scenarios where RACH-less SCG establishment occurs, there may be reasons why RACH-less SCG establishment might not be performed in certain situations. Therefore, there may be conditions under which RACH-less establishment can or cannot be performed. Or, in other cases, these limitations may be related to UE capabilities.

[0199] In one embodiment of the invention, when a failure occurs while attempting to establish an SCG using no RACH, this is reported in the SCGFailureInformation. For example, this could be the use of a no-RACH flag in the SCGFailureInformation RRC message. It could also indicate the N flag used for no-RACH. TA .

[0200] In the following sections of the description, implementation examples are presented in ASN.1 format.

[0201] Example #1

[0202] ----------------Example based on TS 38.331 V18.0.0----------------

[0203] - CellGroupConfig

[0204] CellGroupConfigThe IE (Interceptor) is used to configure the primary cell group (MCG) or secondary cell group (SCG). A cell group consists of a MAC address, a set of logical channels with associated RLC entities, a primary cell (SpCell), and one or more secondary cells (SCells). For NCR-MT, CellGroupConfig IE is also used to configure side control information for NCR-Fwd access links.

[0205] [Table 1]

[0206]

[0207]

[0208]

[0209]

[0210] [Table 2]

[0211]

[0212] [Table 3]

[0213]

[0214] Example #2

[0215] ----------------Example based on TS 38.331 V18.0.0----------------

[0216] - CellGroupConfig

[0217] CellGroupConfig The IE (Interface) is used to configure the primary cell group (MCG) or secondary cell group (SCG). A cell group consists of a MAC entity, a set of logical channels with associated RLC entities, a primary cell (SpCell), and one or more secondary cells (SCells). For NCR-MT, CellGroupConfig IE is also used to configure side control information for NCR-Fwd access links.

[0218] [Table 4]

[0219]

[0220]

[0221]

[0222]

[0223] [Table 5]

[0224]

[0225] [Table 6]

[0226]

[0227] Example #3

[0228] ----------------TS 36.331 V18.0.0----------------

[0229] - MobilityControlInfo

[0230] MobilityControlInfo This includes parameters related to network control mobility to / within E-UTRA.

[0231] [Table 7]

[0232]

[0233]

[0234]

[0235] [Table 8]

[0236]

[0237] Figure 6 The configuration of a UE (terminal) according to an embodiment of this disclosure is shown.

[0238] refer to Figure 6 According to embodiments of this disclosure, the UE may include a transceiver 620 and a controller 610 for controlling the overall operation of the UE. Furthermore, the transceiver 620 may include a transmitter 625 and a receiver 623. Additionally, the UE may include one of a remote user equipment (remote UE) and another remote user equipment (remote UE).

[0239] Transceiver 620 can send signals to or receive signals from other network entities.

[0240] The controller 610 can control the UE to perform one of the operations described in the above embodiments. The controller 610 and transceiver 620 are not necessarily implemented as separate modules and can be implemented by a single element, such as a single chip. Furthermore, the controller 610 and transceiver 620 can be electrically connected. For example, the controller 610 can be a circuit, a dedicated circuit, or at least one processor. Moreover, the operation of the UE can be implemented by including a memory device in any element of the UE, in which corresponding program code is stored.

[0241] Figure 7 The configuration of a base station according to an embodiment of this disclosure is shown.

[0242] refer to Figure 7 According to embodiments of the present disclosure, a base station may include a transceiver 720 and a controller 710 for controlling the overall operation of the base station. Furthermore, the transceiver 720 may include a transmitter 725 and a receiver 723.

[0243] Transceiver 720 can send signals to or receive signals from other network entities.

[0244] The controller 710 can control the base station to perform one of the operations described in the above embodiments. The controller 710 and transceiver 720 are not necessarily implemented as separate modules and can be implemented by a single element, such as a single chip. Furthermore, the controller 710 and transceiver 720 can be electrically connected. For example, the controller 710 can be a circuit, a dedicated circuit, or at least one processor. Additionally, the operation of the base station can be implemented by including a memory device in any element of the base station, in which corresponding program code is stored.

[0245] A base station can refer to a main base station, auxiliary base station, source base station, target base station, MCG, SCG, main node, or auxiliary node.

[0246] It should be noted that Figure 1 a to Figure 7 The configuration diagrams, control / data signal transmission method diagrams, operation process diagrams, and structural diagrams shown do not limit the scope of protection of this invention. That is to say, Figure 1 a to Figure 7 All constituent units, entities or operational steps shown should not be construed as essential elements for implementing this disclosure, and this disclosure can be implemented without prejudice to its true nature even when only some of these elements are included.

[0247] The aforementioned operations of the base station or terminal can be implemented by providing a memory device in the base station or terminal equipment to store the corresponding program code. In other words, the controller of the base station or terminal equipment can perform the aforementioned operations by reading and executing the program code stored in the memory device through a processor or central processing unit (CPU).

[0248] Various units or modules of network entities, base station equipment, or terminal equipment can be operated using hardware circuits such as logic circuits based on complementary metal-oxide-semiconductor (CMOS), firmware, or hardware circuits such as software and / or combinations of hardware and firmware and / or software embedded in machine-readable media. For example, various electrical structures and methods can be implemented using transistors, logic gates, and circuits such as application-specific integrated circuits (ASICs).

[0249] Although specific embodiments have been described in the detailed description of this disclosure, it will be apparent that various modifications and changes can be made thereto without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be defined as limited to the embodiments set forth herein, but rather as defined by the appended claims and their equivalents.

[0250] At least some of the example embodiments described herein can be constructed, in whole or in part, using dedicated hardware. Terms such as 'component,' 'module,' or 'unit' as used herein can include, but are not limited to, hardware devices that perform a particular task or provide associated functionality, such as circuits, field-programmable gate arrays (FPGAs), or application-specific integrated circuits (ASICs) in discrete or integrated component form. In some embodiments, the described elements can be configured to reside on a tangible, persistent, addressable storage medium and can be configured to execute on one or more processors. In some embodiments, these functional elements can include, for example, components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. Although example embodiments have been described with reference to the components, modules, and units discussed herein, these functional elements can be combined into fewer elements or divided into additional elements. Various combinations of optional features have been described herein, and it should be understood that the described features can be combined in any suitable combination. In particular, features of any example embodiment can be appropriately combined with features of any other embodiment, unless such combination is mutually exclusive. Throughout this specification, the terms “comprising” or “comprises” mean that the specified components are included, but do not exclude the presence of other components.

[0251] Note all papers and documents submitted concurrently with or prior to this specification in connection with this application, which are publicly available together with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0252] All features disclosed in this specification (including any appended claims, abstract, and drawings) and / or all steps of any method or process so disclosed may be combined in any combination except for at least some mutually exclusive combinations of such features and / or steps.

[0253] Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by an alternative feature for the same, equivalent, or similar purpose. Therefore, unless otherwise expressly stated, each disclosed feature is merely one example of a general set of equivalent or similar features.

[0254] This invention is not limited to the details of the foregoing embodiments. The invention extends to any novel feature or any novel combination thereof disclosed in this specification (including any appended claims, abstract, and drawings), or to any novel step or any novel combination thereof in any method or process so disclosed.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: Receive a first message from the first base station, including information about a handover without a random access channel (RACH). as well as Based on the information regarding the lack of RACH handover, a second message is sent to the second base station to complete the handover process. Among them, frequency range 1 FR1-FR2 without RACH switching is not supported.

2. The method according to claim 1, in, Information regarding RACH-free handover includes at least one of the following: information about the beam of the Physical Downlink Control Channel (PDCCH) used by the terminal in the target cell to monitor initial uplink transmissions and information about the timing advance value used by the terminal for handover.

3. The method according to claim 1, in, The first message includes information about uplink grants for sending the first message or information for monitoring uplink grants from the second base station, and Sending the second message includes: If the first message includes information for monitoring uplink grants from the second base station, based on information regarding no RACH handover, a Physical Downlink Control Channel (PDCCH) for the uplink grant is received from the second base station; and Based on the uplink authorization, the second message is sent to the second base station.

4. The method according to claim 1, in, The first message includes a message for modifying the Radio Resource Control (RRC) connection.

5. A method performed by a first base station in a wireless communication system, the method comprising: Send a handover request message to the second base station; Receive a handover request confirmation message from the second base station; as well as Send a first message to the terminal, including information about a handover without a random access channel (RACH). The second message used to complete the handover process is sent to the second base station based on information about no RACH handover, and Among them, frequency range 1 FR1-FR2 without RACH switching is not supported.

6. The method according to claim 5, in, Information regarding RACH-free handover includes at least one of the following: information about the beam of the Physical Downlink Control Channel (PDCCH) used by the terminal in the target cell to monitor initial uplink transmissions and information about the timing advance value used by the terminal for handover.

7. The method according to claim 5, in, The first message includes information about uplink grants for sending the first message or information for monitoring uplink grants from the second base station.

8. The method according to claim 5, in, The first message includes a message for modifying the Radio Resource Control (RRC) connection.

9. A terminal in a wireless communication system, the terminal comprising: transceiver; as well as A controller, coupled to the transceiver, is configured to: Receive a first message from the first base station, including information about a handover without a random access channel (RACH). as well as Based on the information regarding the lack of RACH handover, a second message is sent to the second base station to complete the handover process. Among them, frequency range 1 FR1-FR2 without RACH switching is not supported.

10. The terminal according to claim 9, in, Information regarding RACH-free handover includes at least one of the following: information about the beam of the Physical Downlink Control Channel (PDCCH) used by the terminal in the target cell to monitor initial uplink transmissions and information about the timing advance value used by the terminal for handover.

11. The terminal according to claim 9, in, The first message includes information about uplink grants for sending the first message or information for monitoring uplink grants from the second base station, and The controller is further configured as follows: If the first message includes information for monitoring uplink grants from the second base station, based on information regarding no RACH handover, a Physical Downlink Control Channel (PDCCH) for the uplink grant is received from the second base station; and Based on the uplink authorization, the second message is sent to the second base station.

12. The terminal according to claim 9, in, The first message includes a message for modifying the Radio Resource Control (RRC) connection.

13. A first base station in a wireless communication system, the first base station comprising: transceiver; as well as A controller, coupled to the transceiver, is configured to: Send a handover request message to the second base station; Receive a handover request confirmation message from the second base station; as well as Send a first message to the terminal, including information about a handover without a random access channel (RACH). The second message used to complete the handover process is sent to the second base station based on information about no RACH handover, and Among them, frequency range 1 FR1-FR2 without RACH switching is not supported.

14. The first base station according to claim 13, in, Information regarding RACH-free handover includes at least one of the following: information about the beam of the Physical Downlink Control Channel (PDCCH) used by the terminal to monitor initial uplink transmissions in the target cell; and information about the timing advance value used by the terminal for handover. The first message includes a message for modifying the Radio Resource Control (RRC) connection.

15. The first base station according to claim 13, in, The first message includes information about uplink grants for sending the first message or information for monitoring uplink grants from the second base station.

Images