KR20230105311A - Method for changing cell and apparatus thereof - Google Patents

Abstract

The present invention relates to a method for enabling a terminal to change a cell, which quickly controls a cell change operation of a terminal in a lower layer, and an apparatus thereof. According to embodiments of the present invention, the method comprises: a step of receiving a higher layer message containing one or more candidate target cell configuration information for an L1/L2-triggered mobility (LTM) operation; a step of transmitting an L1 measurement result for the candidate target cell on the basis of the higher layer message; a step of receiving a medium access control (MAC) control element (CE) instructing to perform the LTM operation to a target cell; and a step of applying candidate target cell configuration information to the target cell on the basis of the MAC CE to perform a cell change operation without RRC reconfiguration.

Description

Cell changing method and its device {METHOD FOR CHANGING CELL AND APPARATUS THEREOF}

The present disclosure relates to a method and apparatus for changing a cell by a terminal.

As the spread of small wireless communication devices such as smart phones has increased, the number of users has also increased. In particular, wireless communication devices are mounted not only on smart phones but also on various means of transportation such as vehicles and airplanes, enabling communication while moving.

When a wireless communication device moves, movement occurs from one cell coverage to another cell coverage. Also, with the development of high-speed transportation means such as vehicles, the need to change cells is further increasing.

This cell change operation is called handover, and in the related art, an RRC-connected terminal performs handover through RRC signaling. In this way, when handover is performed based on L3 signaling, there is a problem in that the handover procedure of the base station, the core network entity, and the terminal is complicated and takes a long time.

This has a problem in that it is difficult to satisfy the low-latency, high-speed movement requirements required for communication after 5G. In particular, as technology for performing a communication operation at a beam level develops and high-speed movement becomes frequent, user communication quality can be maintained. In this respect, low-latency, overhead, and interruption time reduction technologies are required in the process of performing handover.

The present embodiments can provide a method and apparatus for quickly controlling a cell change operation of a terminal in a lower layer.

In one aspect, the present embodiments are a method for performing a cell change operation by a terminal, comprising the steps of receiving a higher layer message including one or more candidate target cell configuration information for an LTM (L1/L2-triggered mobility) operation; Transmitting the L1 measurement result for the candidate target cell based on the higher layer message, receiving a Medium Access Control Control Element (MAC CE) indicating an LTM operation to the target cell, and It is possible to provide a method including the step of performing a cell change operation without RRC reconfiguration by applying candidate target cell configuration information for the .

In another aspect, the present embodiments are a method for a base station to control a cell change operation of a terminal, which transmits a higher layer message including one or more candidate target cell configuration information for LTM (L1 / L2-triggered mobility) operation Steps of receiving the L1 measurement result for the candidate target cell, determining whether to perform the LTM operation on the target cell based on the L1 measurement result, and MAC CE (Medium Access Control Control Element) instructing the LTM operation to be performed on the target cell. ) may be provided.

In another aspect, the present embodiments provide, in a terminal performing a cell change operation, a receiver receiving a higher layer message including one or more candidate target cell configuration information for an LTM (L1/L2-triggered mobility) operation and a higher level A transmitter for transmitting an L1 measurement result for a candidate target cell based on a layer message and a control unit for performing a cell change operation without RRC reconfiguration by applying candidate target cell configuration information for the target cell based on the MAC CE; may provide a terminal device that receives a Medium Access Control Control Element (MAC CE) indicating performance of an LTM operation to a target cell.

In another aspect, the present embodiments provide a transmitter for transmitting a higher layer message including one or more candidate target cell configuration information for an LTM (L1/L2-triggered mobility) operation in a base station controlling a cell change operation of a terminal. and a receiving unit receiving an L1 measurement result for the candidate target cell and a control unit determining whether to perform an LTM operation on the target cell based on the L1 measurement result, wherein the transmitter instructs performing the LTM operation on the target cell. A base station device transmitting an Access Control Control Element) may be provided.

According to the present embodiments, it is possible to provide a method and apparatus for rapidly performing cell change in a lower layer.

1 is a diagram schematically illustrating the structure of an NR wireless communication system to which this embodiment can be applied.
2 is a diagram for explaining a frame structure in an NR system to which this embodiment can be applied.
3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.
4 is a diagram for explaining a bandwidth part supported by a radio access technology to which this embodiment can be applied.
5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which this embodiment can be applied.
6 is a diagram for explaining a random access procedure in a radio access technology to which this embodiment can be applied.
7 is a diagram for explaining CORESET.
8 is a diagram for describing an operation of a terminal according to an exemplary embodiment.
9 is a diagram for explaining an operation of a base station according to an embodiment.
10 is a diagram illustrating an example of a downlink L2 structure for an LTM radio bearer.
11 is a diagram illustrating an example of an uplink L2 structure for an LTM radio bearer.
12 is a diagram illustrating another example of a downlink L2 structure for an LTM radio bearer.
13 is a diagram illustrating another example of an uplink L2 structure for an LTM radio bearer.
14 is a diagram showing a configuration of a terminal according to another embodiment.
15 is a diagram showing the configuration of a base station according to another embodiment.

DETAILED DESCRIPTION Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present embodiments, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present technical idea, the detailed description may be omitted. When "comprises", "has", "consists of", etc. mentioned in this specification is used, other parts may be added unless "only" is used. In the case where a component is expressed in the singular, it may include the case of including the plural unless otherwise explicitly stated.

Also, terms such as first, second, A, B, (a), and (b) may be used in describing the components of the present disclosure. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the corresponding component is not limited by the term.

In the description of the positional relationship of components, when it is described that two or more components are "connected", "coupled" or "connected", the two or more components are directly "connected", "coupled" or "connected". ", but it will be understood that two or more components and other components may be further "interposed" and "connected", "coupled" or "connected". Here, other components may be included in one or more of two or more components that are “connected”, “coupled” or “connected” to each other.

In the description of the temporal flow relationship related to components, operation methods, production methods, etc., for example, "after", "continued to", "after", "before", etc. Alternatively, when a flow sequence relationship is described, it may also include non-continuous cases unless “immediately” or “directly” is used.

On the other hand, when a numerical value or corresponding information (eg, level, etc.) for a component is mentioned, even if there is no separate explicit description, the numerical value or its corresponding information is not indicated by various factors (eg, process factors, internal or external shocks, noise, etc.) may be interpreted as including an error range that may occur.

A wireless communication system in the present specification refers to a system for providing various communication services such as voice and data packets using radio resources, and may include a terminal, a base station, or a core network.

The present embodiments disclosed below may be applied to wireless communication systems using various wireless access technologies. For example, the present embodiments include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and singlecarrier frequency division multiple access (SC-FDMA). Alternatively, it may be applied to various radio access technologies such as non-orthogonal multiple access (NOMA). In addition, the wireless access technology may mean not only a specific access technology, but also a communication technology for each generation established by various communication consultative organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, CDMA may be implemented as a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/enhanced datarates for GSM evolution (EDGE). OFDMA may be implemented with a wireless technology such as institute of electrical and electronic engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like. IEEE 802.16m is an evolution of IEEE 802.16e, and provides backward compatibility with a system based on IEEE 802.16e. UTRA is part of the universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) that uses evolved-UMTSterrestrial radio access (E-UTRA). Adopt FDMA. As such, the present embodiments may be applied to currently disclosed or commercialized radio access technologies, and may also be applied to radio access technologies currently under development or to be developed in the future.

Meanwhile, a terminal in the present specification is a comprehensive concept meaning a device including a wireless communication module that communicates with a base station in a wireless communication system, and in WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or New Radio) It should be interpreted as a concept that includes not only User Equipment (UE), but also Mobile Station (MS), User Terminal (UT), Subscriber Station (SS), and wireless device in GSM. In addition, the terminal may be a user portable device such as a smart phone depending on the type of use, or may mean a vehicle or a device including a wireless communication module in the vehicle in the V2X communication system. In addition, in the case of a machine type communication system, it may mean an MTC terminal, an M2M terminal, a URLLC terminal, etc. equipped with a communication module to perform machine type communication.

A base station or cell in this specification refers to an end that communicates with a terminal in terms of a network, and includes Node-B (Node-B), eNB (evolved Node-B), gNB (gNode-B), LPN (Low Power Node), Sector, site, various types of antennas, base transceiver system (BTS), access point, point (e.g. transmission point, reception point, transmission/reception point), relay node ), mega cell, macro cell, micro cell, pico cell, femto cell, remote radio head (RRH), radio unit (RU), and small cell. Also, a cell may mean including a bandwidth part (BWP) in the frequency domain. For example, the serving cell may mean the activation BWP of the terminal.

Since there is a base station controlling one or more cells in the various cells listed above, the base station can be interpreted in two meanings. 1) In relation to the radio area, it may be a device itself that provides a mega cell, macro cell, micro cell, pico cell, femto cell, or small cell, or 2) it may indicate the radio area itself. In 1), all devices providing a predetermined radio area are controlled by the same entity or all devices interacting to form a radio area cooperatively are directed to the base station. Points, transmission/reception points, transmission points, reception points, etc., according to the configuration method of the radio area, become an example of a base station. In 2), the radio area itself in which signals are received or transmitted may be indicated to the base station from the viewpoint of the user terminal or the neighboring base station.

In this specification, a cell refers to a component carrier having coverage of a signal transmitted from a transmission/reception point or a coverage of a signal transmitted from a transmission/reception point (transmission point or transmission/reception point), and the transmission/reception point itself. can

Uplink (UL, or uplink) means a method of transmitting and receiving data from a terminal to a base station, and downlink (DL, or downlink) means a method of transmitting and receiving data from a base station to a terminal do. Downlink may mean communication or a communication path from multiple transmission/reception points to a terminal, and uplink may mean communication or communication path from a terminal to multiple transmission/reception points. In this case, in the downlink, the transmitter may be a part of a multi-transmission/reception point, and the receiver may be a part of a terminal. Also, in uplink, a transmitter may be a part of a terminal, and a receiver may be a part of a multi-transmission/reception point.

In uplink and downlink, control information is transmitted and received through control channels such as a physical downlink control channel (PDCCH) and a physical uplink control channel (PUCCH), and a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH). Data is transmitted and received by configuring the same data channel. Hereinafter, the situation in which signals are transmitted and received through channels such as PUCCH, PUSCH, PDCCH, and PDSCH is expressed in the form of 'transmitting and receiving PUCCH, PUSCH, PDCCH, and PDSCH'. do.

For clarity of explanation, 3GPP LTE/LTE-A/NR (New RAT) communication system is mainly described in the following technical idea, but the technical features are not limited to the corresponding communication system.

3GPP develops 5G (5th-Generation) communication technology to meet the requirements of ITU-R's next-generation wireless access technology after research on 4G (4th-Generation) communication technology. Specifically, 3GPP develops new NR communication technology separate from LTE-A pro and 4G communication technology, which has improved LTE-Advanced technology to meet the requirements of ITU-R as 5G communication technology. Both LTE-A pro and NR refer to 5G communication technology. Hereinafter, 5G communication technology will be described focusing on NR when a specific communication technology is not specified.

Operating scenarios in NR defined various operating scenarios by adding consideration to satellites, automobiles, and new verticals in the existing 4G LTE scenarios. It is deployed in the range to support mMTC (Massive Machine Communication) scenarios that require low data rates and asynchronous access, and URLLC (Ultra Reliability and Low Latency) scenarios that require high responsiveness and reliability and can support high-speed mobility. .

In order to satisfy this scenario, NR discloses a wireless communication system to which a new waveform and frame structure technology, low latency technology, mmWave support technology, and forward compatible technology are applied. In particular, the NR system proposes various technical changes in terms of flexibility in order to provide forward compatibility. The main technical features of NR are described below with reference to the drawings.

<NR System General>

1 is a diagram schematically showing the structure of an NR system to which this embodiment can be applied.

Referring to FIG. 1, the NR system is divided into 5GC (5G Core Network) and NR-RAN parts, and NG-RAN controls the user plane (SDAP / PDCP / RLC / MAC / PHY) and UE (User Equipment) It consists of gNB and ng-eNB providing plane (RRC) protocol termination. The gNB mutual or the gNB and ng-eNB are interconnected through the Xn interface. gNB and ng-eNB are each connected to 5GC through NG interface. 5GC may include an Access and Mobility Management Function (AMF) in charge of a control plane such as terminal access and mobility control functions, and a User Plane Function (UPF) in charge of a control function for user data. NR includes support for both frequency bands below 6 GHz (FR1, Frequency Range 1) and above 6 GHz frequency band (FR2, Frequency Range 2).

gNB means a base station that provides NR user plane and control plane protocol termination to a terminal, and ng-eNB means a base station that provides E-UTRA user plane and control plane protocol termination to a terminal. The base station described in this specification should be understood as encompassing gNB and ng-eNB, and may be used to refer to gNB or ng-eNB separately as needed.

<NR wave form, numerology and frame structure>

In NR, a CP-OFDM waveform using a cyclic prefix is used for downlink transmission, and CP-OFDM or DFT-s-OFDM is used for uplink transmission. OFDM technology is easy to combine with multiple input multiple output (MIMO) and has the advantage of using a low-complexity receiver with high frequency efficiency.

On the other hand, in NR, since the requirements for data rate, latency, coverage, etc. are different for each of the three scenarios described above, it is necessary to efficiently satisfy the requirements for each scenario through a frequency band constituting an arbitrary NR system. . To this end, a technique for efficiently multiplexing radio resources based on a plurality of different numerologies has been proposed.

Specifically, the NR transmission numerology is determined based on the sub-carrier spacing and CP (Cyclic prefix), and as shown in Table 1 below, the μ value is used as an exponential value of 2 based on 15 kHz, resulting in an exponential is changed to

μ subcarrier spacing Cyclic prefix Supported for data Supported for synch 0 15 Normal Yes Yes One 30 Normal Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240 Normal No Yes

As shown in Table 1 above, the numerology of NR can be classified into five types according to the subcarrier spacing. This is different from the fact that the subcarrier interval of LTE, which is one of the 4G communication technologies, is fixed at 15 kHz. Specifically, in NR, subcarrier intervals used for data transmission are 15, 30, 60, and 120 kHz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 120, and 240 kHz. In addition, the extended CP is applied only to a 60 kHz subcarrier interval. Meanwhile, a frame structure in NR is defined as a frame having a length of 10 ms composed of 10 subframes having the same length of 1 ms. One frame may be divided into half frames of 5 ms, and each half frame includes 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe consists of one slot, and each slot consists of 14 OFDM symbols.

2 is a diagram for explaining a frame structure in an NR system to which this embodiment can be applied.

Referring to FIG. 2, a slot is fixedly composed of 14 OFDM symbols in the case of a normal CP, but the length of the slot in the time domain may vary according to the subcarrier interval. For example, in the case of a numerology having a 15 kHz subcarrier interval, a slot is 1 ms long and has the same length as a subframe. In contrast, in the case of numerology having a subcarrier interval of 30 kHz, a slot consists of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, subframes and frames are defined with a fixed time length, and slots are defined by the number of symbols, and the time length may vary according to subcarrier intervals.

Meanwhile, NR defines a basic unit of scheduling as a slot, and introduces a mini-slot (or sub-slot or non-slot based schedule) to reduce transmission delay in a radio section. When a wide subcarrier interval is used, the length of one slot is shortened in inverse proportion to a transmission delay in a radio section. Mini-slots (or sub-slots) are for efficient support of URLLC scenarios and can be scheduled in units of 2, 4, or 7 symbols.

Also, unlike LTE, NR defines uplink and downlink resource allocation at the symbol level within one slot. In order to reduce HARQ delay, a slot structure capable of directly transmitting HARQ ACK/NACK within a transmission slot has been defined, and this slot structure is named and described as a self-contained structure.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in 3GPP Rel-15. In addition, a common frame structure constituting an FDD or TDD frame is supported through a combination of various slots. For example, a slot structure in which all symbols of a slot are set to downlink, a slot structure in which all symbols of a slot are set to uplink, and a slot structure in which downlink symbols and uplink symbols are combined are supported. NR also supports that data transmissions are distributed and scheduled over one or more slots. Therefore, the base station can inform the terminal whether the slot is a downlink slot, an uplink slot, or a flexible slot using a slot format indicator (SFI). The base station may indicate the slot format by indicating the index of the table configured through UE-specific RRC signaling using SFI, dynamically indicating through DCI (Downlink Control Information), or static or static through RRC. It can also be given quasi-statically.

<NR physical resources>

Regarding physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, bandwidth parts, etc. are considered do.

An antenna port is defined such that the channel on which a symbol on an antenna port is carried can be inferred from the channel on which other symbols on the same antenna port are carried. Two antenna ports are quasi co-located or QC/QCL (quasi co-located or quasi co-location). Here, the wide range characteristics include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.

Referring to FIG. 3 , since NR supports a plurality of numerologies in the same carrier, a resource grid may exist according to each numerology. Also, resource grids may exist according to antenna ports, subcarrier intervals, and transmission directions.

A resource block consists of 12 subcarriers and is defined only in the frequency domain. Also, a resource element is composed of one OFDM symbol and one subcarrier. Accordingly, as shown in FIG. 3, the size of one resource block may vary according to the subcarrier interval. In addition, in NR, “Point A”, which serves as a common reference point for the resource block grid, and common resource blocks and virtual resource blocks are defined.

4 is a diagram for explaining a bandwidth part supported by a radio access technology to which this embodiment can be applied.

In NR, unlike LTE where the carrier bandwidth is fixed at 20Mhz, the maximum carrier bandwidth is set from 50Mhz to 400Mhz for each subcarrier interval. Therefore, it is not assumed that all terminals use all of these carrier bandwidths. Accordingly, in NR, as shown in FIG. 4, a bandwidth part (BWP) can be designated and used by a UE within a carrier bandwidth. In addition, the bandwidth part is associated with one numerology, is composed of a subset of consecutive common resource blocks, and can be dynamically activated according to time. Up to four bandwidth parts each of uplink and downlink are configured in the terminal, and data is transmitted and received using the active bandwidth part at a given time.

In the case of paired spectrum, the uplink and downlink bandwidth parts are set independently, and in the case of unpaired spectrum, to prevent unnecessary frequency re-tuning between downlink and uplink operations. For this purpose, the bandwidth parts of downlink and uplink are paired to share a center frequency.

<NR initial connection>

In NR, a UE accesses a base station and performs a cell search and random access procedure to perform communication.

Cell search is a procedure in which a UE synchronizes with a cell of a corresponding base station using a synchronization signal block (SSB) transmitted by the base station, acquires a physical layer cell ID, and obtains system information.

5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which this embodiment can be applied.

Referring to FIG. 5, the SSB consists of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) occupying 1 symbol and 127 subcarriers, and a PBCH spanning 3 OFDM symbols and 240 subcarriers.

The UE receives the SSB by monitoring the SSB in the time and frequency domains.

SSB can be transmitted up to 64 times in 5 ms. A plurality of SSBs are transmitted in different transmission beams within 5 ms, and the UE performs detection assuming that SSBs are transmitted every 20 ms period based on one specific beam used for transmission. The number of beams usable for SSB transmission within 5ms may increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted below 3 GHz, SSBs can be transmitted using up to 8 different beams in a frequency band of 3 to 6 GHz, and up to 64 different beams in a frequency band of 6 GHz or higher.

Two SSBs are included in one slot, and the start symbol and the number of repetitions within the slot are determined according to the subcarrier interval as follows.

On the other hand, SSB is not transmitted at the center frequency of the carrier bandwidth, unlike SS of conventional LTE. That is, the SSB can be transmitted even in a place other than the center of the system band, and a plurality of SSBs can be transmitted in the frequency domain when wideband operation is supported. Accordingly, the UE monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster and synchronization raster, which are the center frequency location information of the channel for initial access, are newly defined in NR, and the synchronization raster has a wider frequency interval than the carrier raster, so it can support fast SSB search of the terminal. can

The UE may acquire the MIB through the PBCH of the SSB. MIB (Master Information Block) includes minimum information for the terminal to receive the remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, the PBCH includes information about the position of the first DM-RS symbol in the time domain, information for monitoring SIB1 by the UE (eg, SIB1 numerology information, information related to SIB1 CORESET, search space information, PDCCH related parameter information, etc.), offset information between the common resource block and the SSB (the location of the absolute SSB within the carrier is transmitted through SIB1), and the like. Here, the SIB1 numerology information is equally applied to some messages used in the random access procedure for accessing the base station after the UE completes the cell search procedure. For example, the numerical information of SIB1 may be applied to at least one of messages 1 to 4 for a random access procedure.

The aforementioned RMSI may mean System Information Block 1 (SIB1), and SIB1 is periodically (eg, 160 ms) broadcast in a cell. SIB1 includes information necessary for the terminal to perform an initial random access procedure, and is periodically transmitted through the PDSCH. In order for the terminal to receive SIB1, it needs to receive numerology information used for SIB1 transmission and CORESET (Control Resource Set) information used for SIB1 scheduling through the PBCH. The UE checks scheduling information for SIB1 using the SI-RNTI in CORESET, and acquires SIB1 on PDSCH according to the scheduling information. The remaining SIBs except for SIB1 may be transmitted periodically or may be transmitted according to the request of the terminal.

6 is a diagram for explaining a random access procedure in a radio access technology to which this embodiment can be applied.

Referring to FIG. 6, when cell search is completed, the terminal transmits a random access preamble for random access to the base station. The random access preamble is transmitted through PRACH. Specifically, the random access preamble is transmitted to the base station through a PRACH composed of contiguous radio resources in a periodically repeated specific slot. In general, when a UE initially accesses a cell, a contention-based random access procedure is performed, and when random access is performed for beam failure recovery (BFR), a non-contention-based random access procedure is performed.

The terminal receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), UL Grant (uplink radio resource), temporary C-RNTI (Temporary Cell-Radio Network Temporary Identifier), and TAC (Time Alignment Command). Since one random access response may include random access response information for one or more terminals, the random access preamble identifier may be included to indicate to which terminal the included UL Grant, temporary C-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, a random access-radio network temporary identifier (RA-RNTI).

Upon receiving a valid random access response, the terminal processes information included in the random access response and performs scheduled transmission to the base station. For example, the UE applies TAC and stores the temporary C-RNTI. In addition, data stored in the buffer of the terminal or newly generated data is transmitted to the base station using the UL grant. In this case, information capable of identifying the terminal must be included.

Finally, the terminal receives a downlink message for contention resolution.

<NR CORESET>

The downlink control channel in NR is transmitted in a CORESET (Control Resource Set) having a length of 1 to 3 symbols, and transmits up/down scheduling information, SFI (Slot Format Index), TPC (Transmit Power Control) information, etc. .

In this way, NR introduced the concept of CORESET to secure the flexibility of the system. A control resource set (CORESET) means a time-frequency resource for a downlink control signal. The UE may decode the control channel candidate using one or more search spaces in the CORESET time-frequency resource. A Quasi CoLocation (QCL) assumption for each CORESET is set, which is used for the purpose of notifying the characteristics of the analog beam direction in addition to the delay spread, Doppler spread, Doppler shift, and average delay, which are characteristics assumed by the conventional QCL.

7 is a diagram for explaining CORESET.

Referring to FIG. 7 , a CORESET may exist in various forms within a carrier bandwidth within one slot, and a CORESET may consist of up to three OFDM symbols in the time domain. In addition, CORESET is defined as a multiple of 6 resource blocks up to the carrier bandwidth in the frequency domain.

The first CORESET is indicated through the MIB as part of the initial bandwidth part configuration to allow additional configuration and system information to be received from the network. After establishing a connection with the base station, the terminal may receive and configure one or more CORESET information through RRC signaling.

In this specification, a frequency, frame, subframe, resource, resource block, region, band, subband, control channel, data channel, synchronization signal, various reference signals, various signals, or various messages related to NR (New Radio) can be interpreted in various meanings used in the past or currently used or in the future.

NR mobility

In the conventional NR technology, mobility control for cell change for an RRC-connected UE represents handover through explicit RRC signaling. Cell change can be triggered by L3 measurements, information required to access the target cell (e.g. reconfiguration with Sync, target cell ID, the new C-RNTI, the target gNB security algorithm identifiers for the selected security algorithms , a set of dedicated RACH resources, the association between RACH resources and SSB(s), the association between RACH resources and UE-specific CSI-RS configuration(s), common RACH resources, and system information of the target cell. ), handover could be executed through RRC message signaling. When a cell change is executed, the MAC entity of the corresponding cell group is reset. Then, the UE applies the new C-RNTI value received as the C-RNTI of the cell group. And, the terminal is configured according to the configuration information received for the PHY / MAC / RLC / PDCP / SDAP layer. This causes more delay, overhead, and interruption time compared to beam change (beam level mobility) within the same cell.

Beam level mobility does not require explicit RRC signaling to be triggered in the beam change process. A base station (network) may provide a SSB/CSI resource and resource set to a terminal through RRC signaling, a trigger state for a triggering channel, and a measurement configuration including interference measurement and report configuration. Beam level mobility could be provided through control signaling (e.g. DCI, MAC CE) of the physical layer/MAC layer in the lower layer. SSB-based beam level mobility is based on the SSB associated with the initial downlink BWP. And it can be configured only for downlink BWPs including an initial downlink BWP and an SSB associated with the initial downlink BWP. For other DL BWPs, beam level mobility could be performed only based on CSI-RS. However, in the prior art, beam switching only supported mobility within the same cell (intra-cell).

In the conventional NR technology, cell-level mobility (cell change) is provided based on L3 signaling, resulting in more delay, overhead, and interruption time than beam-level mobility.

This embodiment, devised to solve the above problems, proposes a procedure for providing inter-cell mobility based on L1/L2 (signaling) and a specific method for signaling information and an apparatus for providing the same.

Hereinafter, a method for providing cell level mobility based on 5G NR radio access technology will be described. However, this is for convenience of explanation, and the method can be applied to cell change based on any radio access technology (e.g. 6G). The embodiments described in this disclosure include information elements, procedures, and operation contents specified in any NR standard (e.g. TS 38.321, NR MAC standard, TS 38.331, NR RRC standard). Even if definitions of corresponding information elements, related procedures, and related terminal operation contents are not described in this specification, corresponding contents specified in standard specifications, which are known technologies, may be included in this embodiment.

For convenience of description, a scenario related to the present disclosure will be described first. However, this is for convenience of description, and the present embodiments may be applied to any network deployment scenario other than the scenario below.

Changing the serving cell within one cell group in the NR stand-alone structure (PCell change, SCell change), changing the serving cell within one cell group (e.g. MCG, SCG) in the dual connectivity structure (SpCell (PCell/PSCell ) change, SCell change), cell change based on L1/L2 (signaling) may be performed.

Cell change based on intra-CU intra-DU L1/L2 may be performed between different cells associated with a corresponding DU within an intra-DU connected to the corresponding CU within the intra-CU. For example, corresponding cells may have different PCI (Physical Cell Id) and are synchronized between cells. Cell change based on intra-CU inter-DU L1/L2 may be performed between cells associated with each DU for different DUs connected to the corresponding CU within the intra-CU. For example, corresponding cells may have different PCIs and are not synchronized between cells. For another example, corresponding cells may have different PCIs and synchronized between cells. The embodiments described below may be implemented individually/independently, or may be arbitrarily combined/combined, and it is obvious that this is also included in the scope of the present disclosure.

For convenience of description, a transmission/reception point/TRP/(via the corresponding TRP) that provides one serving cell/PCell/SCell configured/activated in the terminal is defined as a 1 Transmit/Receive Point (TRP) Beam/Beams/BG (Beam group) ) is indicated. This is for convenience of description and may be replaced with any other name (e.g. primary/main/basic/SpCell associated/Serving cell associated TRP/beam/BG). Tx/receive point/TRP/Beam/Beams/BG (Beam group) that provides a PCI (Physical Cell Id) different from the serving cell/PCell/SCell, or Transmit/receive point/TRP/Beam/Beams/BG (Beam group) linked to PCI (Physical Cell Id) is expressed as a second Transmit/Receive Point (TRP). This is for convenience of description and may be replaced with any other name (e.g. secondary/additional/assisting/non-serving cell associated TRP/beam/BG). The second TRP or a cell associated with the second TRP may be configured/unconfigured in the UE. The second TRP or a cell associated with the second TRP may be activated/deactivated for the UE. For one UE, one 1st TRP and one or more 2TRPs may be provided/supported/configured/released/activated/deactivated.

For convenience of description, a cell change that provides low delay and low interruption time based on L1/L2 is referred to as an L1/L2-triggered mobility (LTM) operation. This is for convenience of description and may be replaced with any other name (e.g. low-latency handover, high speed HO, fast HO, low latency HO, L1/L2 signaling based HO, low layer signaling based HO). Here, L1/L2 is arbitrary L1/L2 signaling (e.g. MAC-CE/DCI), L1/L2 execution instruction information, QCL (Quasi Co Location)/TCI (Transmission Configuration Indication) status activation/update/instruction, (L1 It can indicate one or more of L1/L2 execution conditions (based on measurement), L1/L2 events (based on L1 measurement), L1/L2 procedures, and terminal operations in the L1/L2 layer.

Any function described below for LTM operation may be defined as an individual terminal capability and transmitted by a terminal to a base station. Alternatively, certain functions may be combined/combined, defined as corresponding terminal capabilities, and transmitted by the terminal to the base station.

8 is a diagram for describing an operation of a terminal according to an exemplary embodiment.

Referring to FIG. 8, in a method for performing a cell change operation, a terminal may perform a step of receiving a higher layer message including one or more candidate target cell configuration information for an LTM (L1/L2-triggered mobility) operation. It can (S810).

For example, the terminal may receive an RRC message including one or more candidate target cell configuration information from the base station or the TRP. The RRC message may include one or more candidate target cell configuration information, and each candidate target cell configuration information may be separately included for each candidate target cell.

For example, the higher layer message may include at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. The cell group configuration information includes information for configuring a cell group using two or more cells. Identification information on candidate target cell configuration information may include ID or index information. Through this, the terminal can distinguish each candidate target cell configuration information. The bandwidth part identification information may include an ID or index for identifying the bandwidth part (BWP). The TCI state configuration information may include at least one of a TCI state ID, cell index, cell ID, and physical cell identity (PCI). A detailed description of each information other than this will be described in more detail below.

Meanwhile, candidate target cell configuration information includes information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. For example, the terminal measures the channel state of the serving cell or the candidate target cell using candidate target cell configuration information. The terminal transmits the measured channel state or channel quality information to the base station based on the information for transmitting the measurement result included in the candidate target cell configuration information. To this end, information for measurement reporting may be included in candidate target cell configuration information. For example, candidate target cell configuration information may include information such as measurement period, measurement target, measurement reporting period, measurement reporting resource, value related to measurement reporting trigger condition, and the like.

The terminal may perform a step of transmitting the L1 measurement result for the candidate target cell based on the higher layer message (S820).

For example, the terminal may measure the channel state of the serving cell or the candidate target cell by using information for measurement or measurement result transmission included in the aforementioned candidate target cell configuration information. For example, the UE may measure L1-RSRP. As another example, the UE may measure L1-RSRQ. In addition to this, the terminal may measure the channel state of the serving cell or candidate target cell using various measurement schemes capable of measuring channel quality or channel state.

Thereafter, the terminal transmits the measurement result including the L1 measurement result to the base station. For example, the terminal may transmit the measurement result to the base station based on the information for transmission of the measurement result included in the candidate target cell configuration information. For example, the terminal may transmit the measurement result of the corresponding serving cell or candidate target cell to the base station when the condition for triggering transmission of the measurement result is satisfied. As another example, L1 measurement result transmission is triggered when the quality of the measurement result of the candidate target cell is higher than the measurement result of the source PSCell obtained by adding or subtracting an offset. That is, when comparing the measurement result of the source PSCell with the measurement result of the candidate target cell, the measurement result of the source PSCell is compared by adding or subtracting an offset included in the preset or candidate target cell configuration information. If the comparison results show that the candidate target cell has a better channel state, reporting on the measurement result may be triggered.

For example, the base station may determine whether to perform the LTM operation based on the L1 measurement result information of the terminal. As another example, the base station may determine the target cell to be changed through the LTM operation based on the L1 measurement result information of the terminal.

The terminal may perform a step of receiving a MAC CE (Medium Access Control Control Element) instructing the performance of the LTM operation to the target cell (S830).

For example, when the base station determines cell change of the corresponding terminal based on the L1 measurement result information received from the terminal, it may indicate this through MAC CE.

For example, the terminal may receive indication information indicating the execution of the LTM operation included in the MAC CE. As another example, information on a target cell included in the MAC CE may be checked and an LTM operation execution instruction for the target cell may be received.

Through the MAC CE, the UE needs to obtain an LTM operation instruction and information on a target cell to perform cell change. To this end, the MAC CE may include at least one of identification information for candidate target cell configuration information, a TCI state ID, bandwidth part identification information, and a timing advance command. For example, the MAC CE may include identification information for distinguishing candidate target cell configuration information configured in the terminal through a higher layer message. Identification information may be composed of candidate target cell configuration information ID or index information. In addition, the MAC CE may include at least one of a TCI state ID, a bandwidth part ID, and a TAG.

The terminal may perform a step of performing a cell change operation without RRC reconfiguration by applying candidate target cell configuration information for the target cell based on the MAC CE (S840).

For example, when the MAC CE is received, the UE can identify a target cell for performing cell change based on the corresponding MAC CE. For example, the terminal checks identification information on candidate target cell configuration information included in the MAC CE, and checks candidate target cell configuration information assigned to the corresponding identification information and received through a higher layer message. A candidate target cell to which the corresponding candidate target cell configuration information is applied may become a target cell for cell change. That is, identification information assigned to one or more candidate target cell configuration information received through higher layer messages and identification information assigned to candidate target cell configuration information received through MAC CE may be the same. Through this, the terminal can identify the target cell through the MAC CE.

When a target cell is identified, the terminal applies candidate target cell configuration information applied to the corresponding target cell to the terminal. In addition, the terminal performs a cell change operation to the target cell using candidate target cell configuration information of the corresponding target cell without performing the RRC reconfiguration operation.

Meanwhile, one or more candidate target cell configuration information may be stored and applied to the UE until higher layer signaling for releasing the candidate target cell configuration information is received. For example, when a plurality of candidate target cell configuration information is received through a higher layer message, the terminal can complete cell change to the corresponding target cell by applying any one candidate target cell configuration information through the aforementioned MAC CE. . Even after cell change is completed, configuration information of a plurality of candidate target cells may still remain valid. Therefore, if MAC CE indicating LTM operation is received again from the base station after cell change, the terminal effectively uses the stored candidate target cell configuration information to perform cell change operation.

Release, change, addition, etc. of candidate target cell configuration information configured/stored in the terminal can be performed only by separate higher layer signaling for this purpose.

Through the above operation, the terminal can quickly perform a cell change operation at the L1/L2 level. More specific detailed operations will be described in more detail through individual embodiments below.

9 is a diagram for explaining an operation of a base station according to an embodiment.

Referring to FIG. 9, in a method for controlling a cell change operation of a terminal by a base station, the step of transmitting a higher layer message including one or more candidate target cell configuration information for an LTM (L1/L2-triggered mobility) operation is performed. It can be performed (S910).

For example, the base station or the TRP may transmit an RRC message including one or more candidate target cell configuration information to the terminal. The RRC message may include one or more candidate target cell configuration information, and each candidate target cell configuration information may be separately included for each candidate target cell.

For example, the higher layer message may include at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. The cell group configuration information includes information for configuring a cell group using two or more cells. Identification information on candidate target cell configuration information may include ID or index information. Through this, the terminal can distinguish each candidate target cell configuration information. The bandwidth part identification information may include an ID or index for identifying the bandwidth part (BWP). The TCI state configuration information may include at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI). A detailed description of each information other than this will be described in more detail below.

Meanwhile, candidate target cell configuration information includes information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. For example, the terminal measures the channel state of the serving cell or the candidate target cell using candidate target cell configuration information. The terminal transmits the measured channel state or channel quality information to the base station based on the information for transmitting the measurement result included in the candidate target cell configuration information. To this end, information for measurement reporting may be included in candidate target cell configuration information. For example, candidate target cell configuration information may include information such as measurement period, measurement target, measurement reporting period, measurement reporting resource, value related to measurement reporting trigger condition, and the like.

The base station may perform a step of receiving the L1 measurement result for the candidate target cell (S920).

For example, the terminal may measure the channel state of the serving cell or the candidate target cell by using information for measurement or measurement result transmission included in the aforementioned candidate target cell configuration information. For example, the UE may measure L1-RSRP. As another example, the UE may measure L1-RSRQ. In addition to this, the terminal may measure the channel state of the serving cell or candidate target cell using various measurement schemes capable of measuring channel quality or channel state.

Thereafter, the base station receives the measurement result reporting including the L1 measurement result transmitted by the terminal. For example, the terminal may transmit the measurement result to the base station based on the information for transmission of the measurement result included in the candidate target cell configuration information. For example, the terminal may transmit the measurement result of the corresponding serving cell or candidate target cell to the base station when the condition for triggering transmission of the measurement result is satisfied. As another example, L1 measurement result transmission is triggered when the quality of the measurement result of the candidate target cell is higher than the measurement result of the source PSCell obtained by adding or subtracting an offset. That is, when comparing the measurement result of the source PSCell with the measurement result of the candidate target cell, the measurement result of the source PSCell is compared by adding or subtracting an offset included in the preset or candidate target cell configuration information. If the comparison results show that the candidate target cell has a better channel state, reporting on the measurement result may be triggered.

The base station may perform a step of determining whether to perform the LTM operation for the target cell based on the L1 measurement result (S930).

For example, the base station may determine whether to perform the LTM operation based on the L1 measurement result information of the terminal. As another example, the base station may determine the target cell to be changed through the LTM operation based on the L1 measurement result information of the terminal.

In this way, the base station can perform the LTM operation for the terminal and determine a target cell to be changed by the terminal based on the L1 measurement result received from the terminal.

The base station may perform a step of transmitting a MAC CE (Medium Access Control Control Element) instructing the performance of the LTM operation to the target cell (S940).

For example, when the base station determines cell change of the corresponding terminal based on the L1 measurement result information received from the terminal, it may indicate this through MAC CE.

For example, the base station may include and transmit instruction information instructing the performance of the LTM operation to the MAC CE. As another example, the base station may include and transmit information about the target cell to the MAC CE.

Through the MAC CE, the terminal can obtain an instruction for performing an LTM operation and information on a target cell to perform cell change. For example, the MAC CE may include at least one of identification information for candidate target cell configuration information, a TCI state ID, bandwidth part identification information, and a timing advance command. For example, the MAC CE may include identification information for distinguishing candidate target cell configuration information configured in the terminal through a higher layer message. Identification information may be composed of candidate target cell configuration information ID or index information. In addition, the MAC CE may include at least one of a TCI state ID, a bandwidth part ID, and a TAG.

For example, when the MAC CE is received, the UE can identify a target cell for performing cell change based on the corresponding MAC CE. For example, the terminal checks identification information on candidate target cell configuration information included in the MAC CE, and checks candidate target cell configuration information assigned to the corresponding identification information and received through a higher layer message. A candidate target cell to which the corresponding candidate target cell configuration information is applied may become a target cell for cell change. That is, identification information assigned to one or more candidate target cell configuration information received through higher layer messages and identification information assigned to candidate target cell configuration information received through MAC CE may be the same. Through this, the terminal can identify the target cell through the MAC CE.

When a target cell is identified, the terminal applies candidate target cell configuration information applied to the corresponding target cell to the terminal. In addition, the terminal performs a cell change operation to the target cell using candidate target cell configuration information of the corresponding target cell without performing the RRC reconfiguration operation.

Meanwhile, one or more candidate target cell configuration information may be stored and applied to the UE until higher layer signaling for releasing the candidate target cell configuration information is received. For example, when a plurality of candidate target cell configuration information is received through a higher layer message, the terminal can complete cell change to the corresponding target cell by applying any one candidate target cell configuration information through the aforementioned MAC CE. . Even after cell change is completed, configuration information of a plurality of candidate target cells may still remain valid. Therefore, if MAC CE indicating LTM operation is received again from the base station after cell change, the terminal effectively uses the stored candidate target cell configuration information to perform cell change operation.

Release, change, addition, etc. of candidate target cell configuration information configured/stored in the terminal can be performed only by separate higher layer signaling for this purpose.

Through the above operation, the terminal can quickly perform a cell change operation at the L1/L2 level. More specific detailed operations will be described in more detail through individual embodiments below.

Cell change procedure based on L1/L2

In the procedure for providing L1/L2-triggered mobility (LTM) operation, the base station instructs the terminal to configure the LTM operation for the candidate cell through RRC signaling, the terminal stores/applies the configuration for the LTM operation, and An L2 signaling-based cell change execution/apply step may be included. This will be explained below.

Configurations for LTM operation indicated through RRC signaling include LTM candidate/target cell configuration, LTM radio bearer configuration, L1L2 signaling configuration for LTM operation, execution instruction information configuration for LTM operation, TCI state configuration for LTM operation, LTM One or more information among execution conditions/event configurations for operation may be included.

Upon receiving the configuration for the LTM operation, the terminal may store some or all of the configuration included in the corresponding configuration. Upon receiving the configuration for the LTM operation, the terminal may apply some or all of the configurations included in the corresponding configuration. For example, the terminal may define a terminal variable (UE variable) for storing the corresponding configuration and store some/all of the configuration for LTM operation in the corresponding terminal variable.

The UE may transmit an RRC Reconfiguration Complete message to the base station (through the source cell). After receiving the configuration for LTM operation, the UE may maintain the source cell connection. The terminal may monitor/evaluate L1L2 signaling/execution instruction information/TCI status/execution condition/event for LTM operation for the configured/stored candidate/target cell. Alternatively, the terminal may start monitoring/evaluation of L1L2 signaling/execution instruction information/TCI status/execution condition/event.

LTM operation is triggered/initiated/executed/applied based on L1L2 signaling/execution instruction information/TCI status/execution condition/event/related procedure/operation for a terminal whose corresponding configuration is preconfigured/stored through RRC It can be. L1L2 signaling/execution instruction information/TCI state indicated by the base station to the terminal, execution conditions/events configured in the terminal by the base station, and L1/L2 procedures/operations defined in the terminal Can be executed/applied. For example, the terminal may execute/apply the stored configuration for the selected/instructed/triggered candidate/target cell.

For example, when receiving corresponding L1/L2 signaling, some or all of the candidate/target cell configuration (or stored/preconfigured candidate/target cell configuration in the terminal) included in the corresponding RRC reconfiguration message may be applied/executed. Upon receiving the corresponding L1/L2 signaling, the terminal can apply/execute the corresponding configuration stored for the selected candidate/target cell.

For another example, the corresponding candidate/target cell configuration includes cell group configuration (CellGroupConfig), special cell configuration (SpCellConfig), information for identifying the corresponding cell (e.g. PCI, PCI index, serving cell index, arbitrary cell identifier, ID, Configuration identification information, TCI state ID associated with the corresponding cell), handover information (reconfigurationWithSync), candidate/target cell terminal identifier (newUE-Identity/C-RNTI), timer for limiting/controlling LTM time (e.g. t304 or new timer) and SMTC (SSB-based measurement timing configuration, the SSB periodicity/offset/duration configuration of target cell) for candidate/target cell synchronization/measurement.

The timer may perform one or more of the following operations.

The corresponding timer triggers/initiates/executes cell change/handover based on L1L2 signaling/execution instruction information/TCI status/execution condition/event/related procedure/operation when an LTM operation is executed. / When applied, or when the execution condition is satisfied by evaluating the execution condition / event configured in the terminal, or a specific procedure / action (e.g. measurement, event detection, condition satisfaction) in the terminal according to L1 / L2 signaling reception and corresponding configuration , apply TCI state update, etc.) is performed, or apply all/part of the stored/preconfigured corresponding configuration).

The corresponding timer may be stopped when random access to the corresponding candidate/target/SpCell is successfully completed.

The corresponding timer is activated when the corresponding L3/L2/L1 indication/confirmation information (e.g. RRC reconfiguration complete message/RRC reconfiguration message including the corresponding information/MAC-CE/HARQ-ACK/UCI) is received from the corresponding candidate/target/SpCell. can be stopped when

When the corresponding timer expires (for MCG), the RRC reset procedure may be initiated.

When the corresponding timer expires (for MCG), the source cell configuration can be applied.

When the corresponding timer expires (for MCG), connection to the source cell can be attempted.

When the corresponding timer expires (for MCG), random access to the source cell may be initiated.

When the corresponding timer expires (for MCG), if a bearer for LTM operation is configured and RLF has not occurred in the source cell, failure information may be indicated to the source cell/base station.

As the corresponding timer, a conventional T304 timer used in an NR-based handover process may be used. Alternatively, the corresponding timer may be configured and used as a new timer differentiated from the conventional T304 timer.

For another example, upon reception of corresponding L1/L2 signaling, data may be transmitted and received through a radio bearer for a corresponding LTM operation.

For another example, the LTM operation may be triggered/initiated/executed when the base station evaluates the execution condition configured in the terminal and the execution condition is satisfied. And / or when the corresponding L1 / L2 signaling is received, it can be triggered / started / executed if the corresponding execution condition is satisfied. For example, the corresponding execution condition is L1 measurement-based threshold reached, L1 measurement (e.g. L1-RSRP)-based event detection, L1 report/CSI report trigger condition satisfied, L3 measurement-based event detection, valid candidate/target cell configuration (or It may include one or more of stored configuration/preconfiguration) existence, activated TCI state (candidate/target cell) existence, and corresponding resource set configuration. The execution condition/event is configured in association with one or more of (L3) measurement identifier, L1 measurement identifier (e.g. MeasID), L1 report identifier (e.g. L1/CSI-ReportConfigId), L1 event identifier (e.g. eventID), and L3 event identifier. It can be. The corresponding execution condition/event is when the measurement associated with the source cell/source RS/target cell/target RS has a better value than the threshold value, the measurement associated with the source cell/source RS/target cell/target RS reaches the threshold value. When the measurement associated with the target cell/target RS is better than the measurement associated with the source cell/source RS, the measurement associated with the target cell/target RS is the measurement associated with the source cell/source RS. One or more of when the value obtained by adding or subtracting the offset to and when the measurement associated with the source cell / source RS has a value worse than the threshold value and the measurement associated with the target cell / target RS has a value better than the threshold value Events can be configured.

L1/L2 signaling/procedure for L1/L2 based cell change

When the UE is located in an overlapping coverage area of a source cell/1TRP/cell/serving cell associated with the 1st TRP and a target cell/candidate cell/2TRP/cell associated with the 2nd TRP/Non-serving cell, the UE In order to transmit uplink/downlink data not only through the source cell/first TRP/cell/serving cell linked to the first TRP, but also through the target cell/candidate cell/second TRP/cell linked to the second TRP/non-serving cell, may be in sufficient condition. L1/L2 signaling/events/procedures/operations for instructing/triggering/initiating/executing/applying/supporting LTM operations may be defined. Alternatively, conventional L1/L2 signaling (or L1/L2 signaling improved from conventional L1/L2 signaling) may be used in conjunction with an LTM configuration to instruct/trigger/initiate/execute/apply/support an LTM operation. When the terminal receives corresponding signaling (or when a specific procedure/action (e.g. measurement, event detection, condition satisfaction, application of TCI state update, etc.) is triggered/initiated/performed/executed in the terminal according to a related configuration), the terminal Information can be directed to higher layers (e.g. MAC/RLC/RRC). The terminal may indicate one or more pieces of information included/linked to the corresponding signaling/event/procedure/action to a higher layer. The UE may trigger/initiate/execute/apply the LTM operation in the upper layer. The terminal may trigger/initiate/execute/apply cell change according to the stored/preconfigured configuration. The terminal can transmit/receive switching uplink/downlink data from a source cell to a candidate/target cell according to a stored/preconfigured configuration.

For linkage between L1/L2 signaling for instructing/supporting LTM operation and an RRC message including LTM configuration, one or more of the RRC information elements included in the corresponding RRC message may be included in the corresponding L1/L2 signaling and indicated. . For example, the base station may indicate by including one or more information elements included in the LTM configuration in the corresponding L1/L2 signaling. Alternatively, L1/L2 signaling/events/procedures/operations and one or more of RRC information elements included in RRC messages for LTM operations are implicitly linked to each other so that the UE can recognize them. For example, each detailed configuration included in the LTM configuration (LTM candidate/target cell configuration, LTM radio bearer configuration, L1L2 signaling configuration for LTM operation, execution instruction information configuration for LTM operation, TCI state configuration for LTM operation) , Execution conditions/event configurations for LTM operations) by including information for association between corresponding configurations, LTM operations can be linked through corresponding L1/L2 signaling/events/procedures/operations.

For example, the LTM configuration includes any detailed configuration information (e.g. LTM candidate/target cell configuration, LTM radio bearer configuration, L1L2 signaling configuration for LTM operation, execution instruction configuration for LTM operation, LTM operation) included in the corresponding configuration. TCI state configuration for LTM operation, execution condition/event configuration for LTM operation) may include a TCI state ID for triggering/initiating/applying/performing LTM operation. When the terminal configured with the corresponding function receives the corresponding TCI state ID through L1/L2 signaling (e.g. MAC-CE/DCI), it can trigger/initiate/apply/perform the LTM operation.

As another example, PCI (physical cell identity) / PCI index / serving cell index / arbitrary cell identifier / ID / configuration identification information / TCI state ID included in the received LTM configuration (e.g. candidate / target cell configuration information) is L1 / It can also be linked by including it in L2 signaling/event/action.

As another example, PCI (physical cell identity)/PCI index/index/arbitrary cell identifier/ID/configuration identification information/TCI state ID included in LTM candidate/target cell configuration information is used to configure L1L2 signaling for LTM operation, LTM operation Including in one or more configurations of execution instruction information configuration for LTM operation, TCI state configuration for LTM operation, and execution condition / event configuration for LTM operation, corresponding signaling / execution instruction information / TCI state / execution condition / event can be received / detected. At this time, it is possible to trigger/initiate/apply/perform preconfigured/stored LTM operations in the terminal.

As another example, TCI state activation/update/instruction through MAC CE and/or DCI with corresponding L1/L2 signaling/event/procedure/action configured for a cell associated with a target cell/candidate cell/2TRP/2TRP TCI state activation/update/instruction using (or linked to the reference signal) the reference signal of the cell linked to the source cell/1TRP/1TRP, the cell/serving cell linked to the source cell/1TRP/1stTRP Target cell/candidate configured for TCI state activation/update/instruction using (or linked to the reference signal) the reference signal of the target cell/candidate cell/second TRP/cell linked to the second TRP configured for the target cell/candidate configured for the LTM operation TCI state activation/update/instruction using (or linked to the reference signal) the reference signal of the cell/second TRP/cell linked to the second TRP, L1 measurement result linked to the reference signal, L1 measurement-based event/execution condition Detection, L1/CSI reporting, L1/CSI reporting criterion/threshold satisfied, timer running to limit/control LTM operation time (e.g. before the corresponding timer expires), (received from/from upper layer) One or more events/procedures/actions among L3 measurement results and L3 measurement-based events/execution condition satisfaction may be used individually or in any combination.

For example, when corresponding L1/L2 signaling is received, cell change can be triggered/initiated/executed when all corresponding events/execution conditions/standards/thresholds predefined/configured/stored in the terminal are satisfied/detected. . For another example, cell change is triggered when an activated TCI state indicated through MAC CE and/or DCI is associated with one target cell/candidate cell/2TRP/cell associated with the 2nd TRP/Non-serving cell /start/can be executed. For another example, if all activated TCI states indicated through MAC CE and/or DCI are associated with one target cell/candidate cell/second TRP/second TRP-associated cell/non-serving cell, cell change occurs. Can be triggered/initiated/executed.

To activate/update/indicate TCI state based on source/serving cell reference signal (for cells with different PCI) (and/or to activate/update/indicate TCI state based on target/candidate cell reference signal) For), the base station may configure the TCI state for the cell (s) / CC (s) (for LTM operation associated with Intra CU, associated with different PCIs) in the terminal. For example, a corresponding cell/CC may be configured as a secondary cell in a serving cell configuration and identified through a serving cell index. Alternatively, the corresponding cell/CC has a cell index/identifier/ID/TCI state ID to distinguish it (consisting of target cell/candidate cell/second TRP/cell associated with the second TRP/Non serving cell) in the serving cell configuration. It can be defined/assigned and distinguished. Alternatively, the corresponding cell/CC may be configured as a serving cell in the target cell configuration (e.g. LTM configuration or LTM RRC message including reconfiguration with sync) and identified through a serving cell index for distinguishing it. Alternatively, the corresponding cell/CC can be distinguished by defining/allocating a cell index/identifier/ID/TCI state ID to distinguish it in the target cell configuration (e.g. LTM configuration or LTM RRC message including reconfiguration with sync). Alternatively, the corresponding cell/CC may be identified through a PCI/PCI index for identifying the corresponding cell in the corresponding terminal. Alternatively, a source/serving cell and a target/candidate cell for LTM operation in a corresponding terminal may be included in one cell group. Alternatively, a source/serving cell and a target/candidate cell for LTM operation in a corresponding UE may be included in different cell groups. For example (in the case of Intra CU and Inter DU scenarios), the source/serving cell can be included in the MCG and the target/candidate cell can be included in the SCG.

In order to update the (intra-cell) TCI state based on the reference signal of the corresponding cell in the target cell (initiation/execution/application/completion of LTM operation), the base station may configure the corresponding TCI state in the terminal. . To update the (inter-cell) TCI status based on the reference signal of the target cell for the neighbor cell/CC (for LTM operation associated with Intra CU) of the target cell (at LTM operation initiation/execution/application/completion) , the base station may configure the corresponding TCI state to the terminal. In order to update the (inter-cell) TCI state based on the reference signal of the (previous) source cell (initiation/execution/application/completion of LTM operation), the base station may configure the corresponding TCI state in the terminal. The TCI state for the target cell/candidate cell/second TRP/cell associated with the second TRP/Non-serving cell may be configured in the terminal. (At the time of initiating/applying/completion of LTM operation) The serving cell before handover to be used in the cell (target cell/candidate cell/2TRP/cell associated with the 2nd TRP) in which the terminal has completed the LTM operation (or a cell other than the corresponding cell) A TCI state associated with a cell, a source cell prior to handover/a first TRP/a cell linked to the first TRP) may be configured in the UE. (Initiating/applying/completion of LTM operation) In a corresponding cell (target cell/candidate cell/second TRP/cell associated with the second TRP) where the terminal completes the LTM operation, the TCI state associated with the corresponding cell may be configured in the terminal. can

The L1/CSI reporting configuration for the reference signal of the cell/serving cell associated with the source cell/first TRP/first TRP and the TCI status associated with the corresponding reference signal may be indicated to the UE. The L1/CSI reporting configuration for the reference signal of the target cell/candidate cell/second TRP/cell associated with the second TRP/non-serving cell and the TCI state associated with the reference signal may be indicated to the UE. The TCI may include physical cell identity (PCI)/physical cell ID (PCI)/PCI index/linked TRP identification information/TCI state ID.

SSBs of the source cell/first TRP/cell associated with the first TRP/serving cell may be used as a QCL source of the target cell/candidate cell/second TRP/cell associated with the second TRP/Non-serving cell. The CSI-RS resource of the cell/serving cell associated with the source cell/1TRP/1TRP is allowed as a QCL source that points to one SSB, and the corresponding CSI-RS is linked to the target cell/candidate cell/2TRP/2TRP. It can be used as a QCL source for a given cell/non-serving cell. SSBs of the target cell/candidate cell/second TRP/cell associated with the second TRP/non-serving cell may be used as a QCL source of the source cell/first TRP/cell associated with the first TRP/serving cell. Target cell/candidate cell/2TRP/cell associated with 2TRP/non-serving cell's CSI-RS resource is allowed as a QCL source pointing to one SSB, and CSI-RS is assigned to source cell/1TRP/1TRP It can be used as a QCL source of an associated cell/serving cell. The TCI state included in the corresponding configuration for one cell may be linked to a cell having a PCI different from the corresponding cell through QCL information/QCL source.

For (L1) measurement of the target cell/candidate cell/2TRP/cell associated with the 2nd TRP/Non-serving cell, the reference resource set configuration included in the serving cell configuration (ServingCellConfig) (e.g. CSI-MeasConfig/CSI- SSB-ResourceSet) and/or associated trigger/report configuration configuration (e.g. CSI-AperiodicTriggerState, CSI-AssociatedReportConfigInfo) PCI for distinguishing target cell/candidate cell/2TRP/cell associated with the 2nd TRP/Non-serving cell /PCI index/serving cell index/arbitrary cell identifier/ID/configuration identification information/TCI state ID/linked TRP identification information may be included. Through this, it is possible to instruct/configure to perform L1-RSRP measurement/L1 reporting/CSI reporting for the target cell/candidate cell/2TRP/cell associated with the 2nd TRP/Non-serving cell. Or, for a target cell/candidate cell/second TRP/cell associated with the second TRP/Non-serving cell, the configuration for L1 measurement/report linked to the reference resource set for the corresponding cell and the reference resource set for the corresponding cell is the terminal can be indicated. The configuration is PCI/PCI for distinguishing the corresponding cell from the corresponding reference resource set configuration (e.g. CSI-MeasConfig/CSI-SSB-ResourceSet) and/or associated trigger/report configuration configuration (e.g. CSI-AperiodicTriggerState, CSI-AssociatedReportConfigInfo) Index/serving cell index/arbitrary cell identifier/ID/configuration identification information/TCI state ID/linked TRP identification information.

For TCI state updates for instructing/triggering/initiating/associating/supporting LTM operations, a TCI state/state pool may be configured for each cell or each BWP through RRC. Alternatively, in order to update the TCI state for instructing/triggering/initiating/associating/supporting the LTM operation, a TCI state/state pool may be configured for each cell (with configuration information linked to the cell) through RRC. there is. Alternatively, in order to update the TCI state for instructing/triggering/initiating/associating/supporting the LTM operation, the TCI state/state pool is provided for each cell group (all cells/ Common information shared by CCs/BWPs, or TCI status/status pool of one reference/reference/instruction cell/CC/BWP used as TCI status/status pool of another cell/CC/BWP within the cell group of the corresponding terminal ) can be configured. Alternatively, in order to update the TCI state to instruct/trigger/initiate/link/support the LTM operation, the TCI state/state pool (TCI state pool) is provided through RRC to all cells/CCs/BWPs in the UE (or to the UE). Common information shared by cells/CCs/BWPs composed of a specific group, or TCI status/status pool of one reference/reference/instructor cell/CC/BWP within a corresponding terminal TCI status of another cell/CC/BWP /can be configured to be used as a statepool.

Here, the cell group may represent a subset of serving cells composed of PCell/PSCell and zero or more secondary cells, such as MCG/SCG. Alternatively, the cell group may represent a PCell/PSCell, 0 or more secondary cells, and a subset of cells that can be configured with 0 or more secondary cells. Alternatively, the cell group may represent a subset of cells composed of a source cell and a target/candidate cell. Alternatively, the cellgroup may represent a subset of cells associated with the first TRP and cells associated with the second TRP. Alternatively, the cell group includes PCell/PSCell, 0 or more secondary cells, 0 or more cells configurable as secondary cells, 0 or more serving cells/cells linked to the 1st TRP, 0 or more non-serving cells/2 TRPs It may indicate a subset of cells including one or more of the associated cells. Alternatively, the cell group may indicate a group composed of one or more cells configured in one terminal as indicated by the base station.

TCI status may consist of separate DL/UL TCI. One downlink TCI state and one uplink TCI state may be indicated through individual state IDs. One downlink TCI status may be indicated by one downlink TCI status ID. One uplink TCI state may be indicated by one uplink TCI state ID. Separate TCI state IDs may be configured for downlink and uplink. Or, one downlink TCI state ID can be associated with one common/Joint TCI state ID. One uplink TCI state ID can be associated with one Common/Joint TCI state ID. One downlink TCI state ID and one uplink TCI state ID pair can be associated with one common/Joint TCI state ID.

TCI status may consist of joint DL/UL TCI. One downlink TCI state configuration and one uplink TCI state configuration may be combined and indicated through one (common/joint) TCI state ID. One downlink TCI state and one uplink TCI state pair can be combined and indicated/configured through one (common/joint) TCI state ID. One downlink TCI state ID and one uplink TCI state ID pair may be individually associated with one common TCI state ID. Information for distinguishing whether the corresponding TCI state ID is DL, UL, or Joint may be configured. Alternatively, the MAC CE and/or DCI signaling for instructing/triggering/initiating/associating the LTM operation may be limited to cases including the joint TCI state ID. A separate DL/UL TCI may share a TCI state pool with a joint DL/UL TCI. Each TCI state may be linked to PCI (Physical Cell Id) / PCI index / TRP (first TRP) of the corresponding serving cell or to PCI / PCI index / TRP (second TRP) of a cell other than the corresponding serving cell. The PCI index may indicate an index/identifier for identifying a PCI within a PCI set configured in the UE for LTM operation (or inter-cell beam management). The PCI index may consist of bit values less than PCI. For example, in RRC, PCI can have an integer value from 0 to 1007, which may require 10 bits. If the maximum number of cells preconfigured for LTM operation is set to 4 or 8, the corresponding cell may be indicated through a 2-bit or 3-bit PCI index.

The RRC configuration for the TCI state/state pool used for TCI state update for instructing/triggering/initiating/associating/supporting the LTM operation is the PCell associated with the source cell/first TRP/first TRP. /SpCell may be indicated to the terminal. The corresponding configuration may include information for distinguishing a cell associated with the target cell/candidate cell/second TRP/second TRP. The UE is instructed to change the cell from a cell associated with the source cell/first TRP/first TRP to a cell associated with the target cell/candidate cell/second TRP/second TRP according to L1/L2 signaling/event/procedure/operation. If so, the UE can trigger/initiate/execute/apply the LTM operation.

Alternatively, the RRC configuration for the TCI state/state pool used for TCI state update for instructing/triggering/initiating/associating/supporting the LTM operation is configured in the target cell/candidate cell/2nd TRP/2nd TRP. The associated cell may be indicated to the UE as PCell/SpCell. The UE is instructed to change the cell from a cell associated with the source cell/first TRP/first TRP to a cell associated with the target cell/candidate cell/second TRP/second TRP according to L1/L2 signaling/event/procedure/operation. Once done, you can trigger/initiate/execute/apply the LTM action.

TCI state/state pool configuration of a cell associated with the source cell/first TRP/first TRP (configured by RRC) and TCI state/state pool configuration of a cell associated with the target cell/candidate cell/second TRP/second TRP ( or some configurations) may be instructed/applied/configured to the terminal with the same configuration/configuration parameter values. Alternatively, the TCI state/state pool configuration of the cell associated with the source cell/first TRP/first TRP is used/replaced/referenced as the TCI state/state pool configuration of the cell associated with the target cell/candidate cell/second TRP/second TRP. can be logged. For example, if there is no TCI state/state pool configuration for a cell linked to the target cell/candidate cell/second TRP/second TRP, the TCI state/state pool of the cell linked to the source cell/first TRP/first TRP Using the configuration as a criterion/reference, the corresponding configuration can be replaced with a TCI state/state pool configuration for a target cell/candidate cell/second TRP/cell associated with the second TRP.

Alternatively, the TCI state/state pool configuration of the cell associated with the target cell/candidate cell/2TRP/2TRP is used/replaced/referenced as the TCI state/statepool configuration of the cell associated with the source cell/1TRP/1st TRP. can be logged. For example, if there is no TCI state/state pool configuration for a cell associated with the source cell/first TRP/first TRP, reference is made to the TCI state/state pool configuration of the cell in the target cell/candidate cell/second TRP/second TRP. As a result, the corresponding configuration can be replaced with the TCI state/state pool configuration for the cell associated with the source cell/first TRP/first TRP.

Alternatively, the TCI state/state pool configuration of a specific serving cell may be indicated as a use/replacement/reference to a TCI state/state pool configuration of a cell having PCI different from that of the corresponding cell. For example, if there is no TCI state/state pool configuration for one cell, the TCI state/state pool configuration for that cell is based on the TCI state/state pool configuration of a cell that has a different PCI from that cell as a reference. composition can be replaced.

Meanwhile, L1-RSRP reporting/CSI reporting/L1 reporting may be transmitted to the base station. L1-RSRP can be calculated and reported for each PCI/PCI index/TRP. For example, the number of bits can be reduced (e.g. 4 bits) by using a (relative) difference value for a PCI/PCI index/TRP specific reference (7 bit) L1-RSRP value. For another example, the corresponding reporting may include PCI/PCI index/serving cell index/arbitrary cell ID/configuration identification information/TCI state ID. Alternatively, L1-RSRP may be calculated and reported regardless of PCI/PCI index/TRP. For example, the number of bits can be reduced (e.g. 4 bits) by using the (relative) difference value for the reference (7-bit) L1-RSRP value. One or more L1-RSRP measurement values may be indicated to the base station through one L1-RSRP reporting.

A resource set (e.g. CSI-SSB-ResourceSet) for L1-RSRP measurement/reporting may be configured in the UE. A corresponding resource set may include a set of SSB indices. The SSB may be linked to the PCI/PCI index/TRP of the serving cell or may be linked to the PCI/PCI index/TRP of a cell other than the serving cell.

To support the LTM operation, CSI reporting/L1-RSRP reporting/L1 reporting/LTM triggering operations may be performed based on execution conditions/events/standards/thresholds. An event for this may be defined and configured in the terminal by the base station. The reporting may include one or more of event name, event identification information, event index, TCI state indication information, TCI state ID, and PCI/PCI index/serving cell index/arbitrary cell ID/configuration identification information.

TCI status update/activation/instruction may be provided to instruct/trigger/associate LTM operation via MAC CE and/or DCI. The MAC CE may indicate active one or more TCI states in the TCI state pool configured by RRC. If a plurality of TCI states are activated, the DCI can select/instruct one TCI state among the activated ones (through a codepoint/TCI field associated with the TCI state). If one TCI state is activated, an implicitly activated TCI state may be selected without an additional DCI instruction. As another example, if a plurality of TCI states are activated and all of the corresponding TCI states are linked to one target/candidate cell, the TCI state corresponding to the order indicated by the first/last/low/high/RRC may be selected. there is.

The number of codepoints activated through MAC CE-based TCI status update/activation/instruction for instructing/triggering/associating/supporting LTM operation may be one or more (e.g. 8). The number of codepoints in the TCI field for DCI-based beam indication/TCI state update/TCI state activation for instructing/triggering/associating/supporting LTM operation may be one or more. The corresponding number may be configured differently according to terminal capabilities.

The number of PCIs different from the serving cell associated with MAC CE-based TCI state activation indication and/or activated TCI state for DCI-based beam indication/TCI state update/TCI state activation to direct/trigger/associate/support LTM operation may be configured differently depending on the terminal capability. The number of PCIs different from the serving cell linked to the activated TCI state for MAC CE-based TCI state activation instruction and/or DCI-based beam indication/TCI state update/TCI state activation may be one or more.

A MAC CE may be defined to instruct/trigger/associate/support LTM operation. The corresponding MAC CE includes serving cell ID, serving cell BWP ID, serving cell SUL, candidate/target cell ID/PCI/PCI index, target cell BWP ID, target cell SUL, candidate/target cell configuration identification information, serving/target cell , beam/cell change application time, CSI-RS resource/resource set ID, SRS resource/resource set ID, TCI state, PCI/PCI index, extended field, CORESET Pool ID, CORESET ID, PUCCH resource/resource Set ID, temporary RS trigger for LTM operation, triggering time offset of corresponding/associated RS, resource used for corresponding/associated RS, QCL source for corresponding/associated RS, corresponding/associated RS burst number, index/identifier for identifying RRC configuration/configuration information including parameters (e.g. one or more of the above parameters) for the corresponding/associated RS, C-RNTI, UL Grant, Timing Advance command, and RACH-specific configuration information One or more of the information may be included.

Here, the serving cell ID represents a serving cell identifier to which MAC CE (or any field included in MAC CE) is applied. The candidate/target cell ID/PCI/PCI index may indicate a cell identifier/PCI/PCI index of a target/handover cell in which cell change is performed according to the LTM operation. The BWP ID is a codepoint of the DCI bandwidth part indicator field and represents a DL BWP to which MAC CE (or any field included in the MAC CE) is applied. SUL indicates whether the MAC CE (or any field included in the MAC CE) applies to the NUL carrier or the SUL carrier (This field is set to 1 to indicate that it applies to the SUL carrier configuration, and it is set to 0 to indicate that it applies to the NUL carrier configuration).

Candidate/target cell configuration identification information represents information for linking a configuration for an LTM operation (or a corresponding detailed configuration, or candidate/target cell configuration) included in a corresponding RRC message. Serving/target cell status is information indicating whether any information field included in the MAC CE is linked/included/corresponded to the serving cell or linked/included/corresponded to the target cell. can be directed. The beam application time is a time during which a corresponding beam/TCI state is applied, and a value indicated/configured by the base station may be used. Alternatively, the cell change application time is the time at which the corresponding cell change is applied, and a value indicated/configured by the base station may be used. The CSI-RS resource/resource set ID indicates an index of an NZP-CSI-RS-ResourceSet including Semi Persistent NZP CSI-RS resources or a resource identifier used for deriving/associating a corresponding TCI state. The SRS resource/resource set ID represents a (semi persistent) SRS resource set identifier identified through the SRS resource set identifier or a resource identifier used for inducing/associating a corresponding TCI state.

The TCI state may include a TCI state ID to be activated. Alternatively, the TCI state includes the TCI state ID (TCI-StateId) of the TCI state used (or applicable) as a QCL source for resources in the corresponding CSI-RS resource set/SRS resource set/control resource set (to be activated). can do. Alternatively, the TCI state may indicate an activation/deactivation state of the TCI state with TCI state ID i. The TCI state may be composed of a bitmap indicating an activation/deactivation state for each configured TCI state ID. For example, if the corresponding field is set to 1/0 (or 0/1), the TCI state having the TCI state identifier i may be activated/deactivated. The activated TCI state identifier may be mapped to a codepoint on a field (e.g. Transmission Configuration Indication) included in DCI. A codepoint to which a TCI state is mapped may be determined by an ordinal position among all TCI states/TCI state IDs having an activated TCI state in a corresponding bitmap. The TCI state may indicate a common/joint DL/UL TCI state ID. Alternatively, the TCI state may be configured with a downlink TCI state ID field and an uplink TCI state ID field to indicate separate DL/UL TCI. Alternatively, the corresponding MAC CE may include a field indicating whether the corresponding TCI state indicates a joint DL/UL TCI state or a separate DL/UL TCI state. Alternatively, the corresponding MAC CE may use only the joint DL/UL TCI state ID. Alternatively, the TCI state/TCI state ID (e.g. joint DL/UL TCI state, separate DL/UL TCI state, both) for linking to the LTM operation may be indicated to the UE through RRC. If the activation/deactivation state is indicated through the above-mentioned bitmap, the above-mentioned bitmap can be configured according to the order of the corresponding TCI state/TCI state ID. One TCI state may be used as a QCL source for one or more of PDSCH/PDCCH/PUCCH/PUSCH/CSI-RS resource set/SRS resource set. Each TCI state is QCL (quasi co-location ) can include parameters to configure the relationship. The corresponding TCI state may include only the TCI state associated with the second TRP. Alternatively, the corresponding TCI state may include a TCI state linked to both the first TRP and the second TRP. Alternatively, the MAC CE for the LTM operation (for indicating the TCI state associated with the 2nd TRP) may be defined as a MAC CE having a separate LCID. The extension field may indicate a flag for indicating whether the corresponding TCI state is the last TCI state or not. Alternatively, the extension field may indicate a flag indicating whether an octet including a corresponding TCI state ID exists. A value of 1/0 can be used to indicate this as a distinction.

The PCI/PCI index may indicate a PCI/PCI index associated with a corresponding TCI status identifier. The CORESET Pool ID indicates the CORESET Pool ID/ControlResourceSetId specific to the corresponding TCI state (This field set to 1 indicates that this MAC CE shall be applied for the DL transmission scheduled by CORESET with the CORESET pool ID equal to 1, otherwise, this MAC CE shall be applied for the DL transmission scheduled by CORESET pool ID equal to 0.).

The CORESET ID represents a control resource set applicable/available to the corresponding TCI state identified with the control resource set identifier (In case the value of the field is 0, the field refers to the Control Resource Set configured by controlResourceSetZero). The PUCCH resource/resource set ID represents a PUCCH resource identifier identified by the PUCCCH resource identifier or a resource identifier used for deriving/associating a corresponding TCI state. Temporary RS for LTM operation indicates Temporary RS bursts for LTM operation, and the number of corresponding RS bursts and a candidate value for triggering offset may be configurable with RRC. C-RNTI represents a UE identifier (newUE-Identity/C-RNTI) to be used in a candidate/target cell. The UL Grant indicates resources to be used on the uplink in the candidate/target cell. The Timing Advance command indicates an index value used to control the amount of timing adjustment to be applied by the corresponding MAC entity. (The Timing Advance Command field indicates the index value TA used to control the amount of timing adjustment that the MAC entity has to apply in TS 38.213). RACH-specific configuration information (rach-ConfigDedicated, for example, RA occasion for contention free random access, msgA-PUSCH-Resource-Index, ra-PreambleIndex, SSB-index, etc.) is random access configuration information used for cell change indicate

Here, CSI-RS resource/resource set ID, SRS resource/resource set ID, DL/UL TCI status, PCI/PCI index, CORESET Pool ID, CORESET ID, PUCCH resource/resource set ID, temporary RS trigger for LTM operation information included in the source cell configuration and the target cell information included in the source cell configuration It can be divided into information included/linked to the configuration and included in each field. Alternatively, only information included in/associated with the source cell configuration may be included. Alternatively, only information included/associated with the target cell configuration may be included.

The corresponding MAC CE is divided into a MAC CE for indicating joint DL/UL TCI activation/deactivation and a MAC CE for indicating separate DL/UL TCI activation/deactivation, and may be defined with a separate LCID. Alternatively, the corresponding MAC CE may be defined as a MAC CE having one LCID capable of supporting both joint DL/UL TCI activation/deactivation and separate DL/UL TCI activation/deactivation. The MAC CE for indicating the temporary RS for LTM operation is defined with a separate LCID, and may be indicated to the terminal together with the aforementioned arbitrary MAC CE.

Using MAC CE and / or DCI, the source cell / first TRP / cell associated with the first TRP / serving cell configured in the terminal and the target cell / candidate cell / second TRP / cell associated with the second TRP / non-serving cell Across, TCI state ID update/activation providing QCL information for PDCCH/PDSCH/CSI-RS dedicated to UE and/or uplink TX spatial filter(s) for PUSCH/PUCCH/SRS dedicated to UE May be provided/instructed.

The base station may transmit TCI state activation/deactivation MAC CE and/or DCI to the terminal to indicate/trigger/initiate/support the LTM operation. The base station (UE-specific/Non-UE-specific) PDSCH/PDCCH/PUCCH/PUSCH/CSI-RS resource set/SRS resource set of a cell (or target cell) having a PCI different from that of the serving cell through the 2 TRP. It is possible to activate / deactivate the configured TCI state for (for PDSCH / PDCCH reception). The base station, through the 2 TRP, DCI for the PDSCH / PDCCH / PUCCH / PUSCH / CSI-RS resource set / SRS resource set (for PDSCH / PDCCH reception) of the cell (or target cell) having PCI different from that of the serving cell You can enable/disable the configured TCI state for the codepoint in the transmission configuration indication field. The configured TCI for the PDSCH/PDCCH/PUCCH/PUSCH/CSI-RS resource set/SRS resource set is initially deactivated when receiving an RRC reconfiguration message. When performing the LTM operation, cell change/handover may be performed with the TCI configured for the PDSCH/PDCCH/PUCCH/PUSCH/CSI-RS resource set/SRS resource set activated. Therefore, after the LTM operation, the TCI configured for the PDSCH/PDCCH/PUCCH/PUSCH/CSI-RS resource set/SRS resource set may be in an activated state. Alternatively, an activated state may be maintained during handover. Alternatively, an activated state may be maintained while the indicated timer operates. Alternatively, the active state may be maintained until explicit signaling (e.g. L3/L2/L1 indication/confirmation information) defined by the base station is indicated/received. Alternatively, the active state may be maintained until a specific point in time included herein.

The base station may instruct TCI state ID update/activation through MAC CE and/or DCI. When the terminal (MAC entity) receives the corresponding MAC CE through the serving cell/1st TRP, the terminal may indicate information about the corresponding MAC CE to the lower/physical layer. The UE receives the TCI state update/activation MAC CE/instruction/command through the received activation TCI state in the DCI and includes the code point of the corresponding field (e.g. 'Transmission Configuration Indication' or any field defined for LTM operation). can be mapped to The UE may apply a TCI state corresponding to a codepoint/value of a corresponding field included in DCI. The terminal may apply the received TCI state ID. When the UE transmits the PUCCH having the HARQ ACK information corresponding to the PDSCH carrying the corresponding activation MAC CE/instruction/command in slot n, the mapping between the TCI state and the codepoint of the corresponding field included in the DCI is performed by the base station after the corresponding slot n. It can be applied to the specific application time calculated using the parameter indicated by The terminal may apply the corresponding TCI state to the corresponding application time.

The UE may trigger/initiate/execute/apply the LTM operation. For example, the LTM operation may be triggered/initiated/executed/applied at the corresponding application time (or after the application time, or after the additional time/offset indicated/configured by the base station). The terminal may instruct the LTM operation to a higher layer (e.g. RRC). The lower layer (PHY/MAC) of the terminal may deliver the corresponding information to MAC/RLC/PDCP/RRC. An upper layer of the UE may trigger/initiate/execute/apply cell change.

Hereinafter, embodiments of CU-DU signaling, radio bearer configuration, and the like for L1/L2-based cell change (LTM operation) of the present invention will be additionally described.

NR is a separation structure that separates a base station (gNB) from a concentration node (hereinafter referred to as gNB-CU for convenience of description) and a distributed node (hereinafter referred to as gNB-DU for convenience) to support efficient network construction. to provide. A wireless network consists of a set of base stations connected to a 5G core network (5GC) through an NG interface. Base stations are interconnected through an Xn interface. One base station may consist of one gNB-CU and one or more gNB-DUs. The gNB-CU and gNB-DU are connected through the F1 interface. One gNB-DU can be connected to only one gNB-CU. An NG interface and an Xn-C interface for one base station composed of the gNB-CU and gNB-DU are terminated at the gNB-CU. The gNB-DUs connected to the gNB-CU are visible to other base stations and 5GC as only one base station. The gNB-CU is a logical node hosting the base station's RRC, SDAP and PDCP protocols. The gNB-DU is a logical node hosting the base station's RLC, MAC and PHY layers. One gNB-DU supports one or a plurality of cells. One cell is supported by only one gNB-DU.

As an example, LTM operation determination may be performed in the CU. For example, based on RRM measurements, etc., the CU can determine the LTM operation. When the LTM operation is determined in the CU, the CU may transmit an F1AP message for instructing the LTM operation to the DU to the DU. The corresponding message may include one or more pieces of information included in this specification. The DU may indicate L1/L2 signaling for LTM operation to the UE. A DU may transmit a reference signal associated with L1/L2 signaling.

As another example, LTM operation determination may be performed in the DU. For example, based on L1 reporting (e.g. CSI report), the DU may determine the LTM operation. The DU may indicate L1/L2 signaling for LTM operation to the UE. A DU may transmit a reference signal associated with L1/L2 signaling. The DU may transmit an F1AP message to the CU to notify the CU that L1/L2 signaling for LTM operation has been instructed to the UE. The corresponding message may include one or more pieces of information included in this specification. When the CU receives the message, the CU's RRC/PDCP may perform one or more operations according to the present specification.

When cell change/handover is triggered/initiated/executed/applied based on L1L2 signaling/execution instruction information/TCI status/execution condition/event/related procedure/operation, or execution condition/event configured in the terminal When an execution condition is satisfied by evaluating , or when a specific procedure/action (e.g. measurement, event detection, condition satisfaction, TCI status update application, etc.) is performed in the terminal according to L1/L2 signaling reception and corresponding configuration, the corresponding Some or all of the configurations included in the RRC reconfiguration message (or configurations of candidate/target cells stored/preconfigured in the UE) may be applied.

When cell change/handover is triggered/initiated/executed/applied based on L1L2 signaling/execution instruction information/TCI status/execution condition/event/related procedure/operation, or execution condition/event configured in the terminal When an execution condition is satisfied by evaluating , or when a specific procedure/action (e.g. measurement, event detection, condition satisfaction, TCI status update application, etc.) is performed in the terminal according to L1/L2 signaling reception and corresponding configuration, the corresponding It can be processed to transmit and receive data through a radio bearer for LTM operation. For example, the UE can transmit/receive by switching uplink/downlink data from a source cell to a candidate/target cell. For another example, uplink/downlink data may be transmitted/received by switching from an L2 entity associated with a source cell to an L2 entity associated with a candidate/target cell.

The radio bearer for LTM operation may be applied/configured/stored to the terminal when the base station instructs the terminal to configure the LTM through RRC signaling. Alternatively, the radio bearer for LTM operation may be applied/configured to the terminal (according to the stored configuration) when receiving the corresponding L1/L2 signaling.

For example, a radio bearer for LTM operation may use the same radio bearer structure as a general data radio bearer (DRB) or signaling radio bearer (SRB) in which one PDCP entity, one RLC entity, and one MAC entity are associated. . As another example, a radio bearer for LTM operation may be configured by adding advanced functions to an L1/L2 entity included in/associated with a general data radio bearer/signaling radio bearer structure. For example, the radio bearer used by the UE in the source cell and the L1/L2 entity (one PDCP entity, one RLC entity, one MAC entity) associated with the radio bearer for one or more parameters (or for all parameters) ) With the same configuration and/or continuous/maintained PDCP/RLC/MAC state variables/buffers/timers/parameter values, the target cell can be reconfigured/set/maintained for use. For example, a value stored in a corresponding PDCP entity in a source cell may be used as an initial value without setting 0 as an initial value for corresponding state variables (e.g. TX_NEXT, RX_NEXT, RX_DELIV, RX_REOR) for a corresponding radio bearer. For convenience of explanation, only PDCP state variables are described, but this is only for convenience of explanation, and it is obvious that arbitrary RLC state variables and arbitrary MAC parameters are also included in the scope of the present disclosure.

As another example, a radio bearer for LTM operation may include one or more of radio bearers (e.g. DRB, SRB) described below for fast switching. For convenience of description, an arbitrary radio bearer used in the process of an LTM operation included in the present disclosure is denoted as an LTM radio bearer. This is for convenience of explanation and may indicate an arbitrary radio bearer configured in the terminal when performing the LTM operation. A corresponding radio bearer may be provided through one type/L2 structure, or may be provided by defining one or more types/L2 structures according to a corresponding scenario.

10 is a diagram illustrating an example of a downlink L2 structure for an LTM radio bearer.

Referring to FIG. 10, an LTM radio bearer may have a split structure in which one PDCP entity has two RLC entities (AM/UM) (one PDCP entity is associated with two RLC entities). Each RLC entity can be associated with one MAC entity. For example, between cells associated with a corresponding DU within an intra-DU (intra-DU) / gNB / gNB-DU connected to a corresponding CU within an intra-CU / gNB (intra-CU / gNB-CU) based on L1 / L2 A cell change may be performed.

11 is a diagram illustrating an example of an uplink L2 structure for an LTM radio bearer.

Referring to FIG. 11, an LTM of a split structure in which one PDCP entity has two RLC entities (AM/UM) within one cell group (e.g. MCG) (one PDCP entity is linked to two RLC entities). A radio bearer may be configured in a terminal. Each RLC entity may be associated with a single MAC entity.

12 is a diagram illustrating another example of a downlink L2 structure for an LTM radio bearer.

Referring to FIG. 12, an LTM radio bearer may have a split structure in which one PDCP entity has two RLC entities (AM/UM) (one PDCP entity is associated with two RLC entities). Each RLC entity may be associated with each MAC entity. For example, intra-CU inter-DU L1/L2 based cell change may be performed between cells associated with each DU for different DUs connected to the corresponding CU within the intra-CU.

13 is a diagram illustrating another example of an uplink L2 structure for an LTM radio bearer.

Referring to FIG. 13, an LTM of a split structure in which one PDCP entity has two RLC entities (AM/UM) within one cell group (e.g. MCG) (one PDCP entity is linked to two RLC entities). A radio bearer may be configured in a terminal. Each RLC entity may be associated with each MAC entity associated with each cellgroup (e.g. MCG, SCG).

LTM operation configuration through RRC signaling may include one or more candidate/target cell configurations. If one or more candidate cells are provided, additional L2 entities for supporting the corresponding candidate cells may be configured in association with each other.

For example, when two candidate cells are provided in the structure of FIG. 10 and/or FIG. 11, three RLC entities may be linked to one PDCP entity. When handover to a specific candidate/target cell is successfully completed, the remaining RLC entities may be released. Alternatively, if handover to a specific candidate/target cell is successfully completed, the remaining RLC entities may be maintained. Through this, L1/L2-based cell change can be triggered/initiated/applied/performed until release of the corresponding candidate cell is instructed through RRC signaling thereafter. For another example, when two candidate cells are provided in the structure of FIG. 12 and/or FIG. 13 , three RLC entities may be linked to one PDCP entity. Each RLC entity may be associated with each MAC entity. When handover to a specific candidate/target cell is successfully completed, the remaining RLC entities and MAC entities may be released. Alternatively, when handover to a specific candidate/target cell is successfully completed, the remaining RLC entities and MAC entities may be maintained. Through this, L1/L2-based cell change can be triggered/initiated/applied/performed until release of the corresponding candidate cell is instructed through RRC signaling thereafter.

For another example, when two candidate cells are provided in the structures of FIGS. 10 to 13, the number of activated RLC entities (used for LTM operation) associated with one PDCP entity may be limited to two. The number of PCIs different from the serving cell associated with the activated TCI state may be limited to one. The number of RLC entities (or RLC entities/MAC entities) associated therewith may be limited to two. When receiving corresponding L1/L2 signaling, the corresponding L2 entity may be activated/configured/applied/used/configured/added.

For another example, an RLC entity (or RLC entity/MAC entity) associated with a cell having a PCI different from a serving cell associated with an inactive TCI state may be configured in an inactive state. When receiving corresponding L1/L2 signaling, the corresponding L2 entity may be activated/configured/applied/used/configured/added.

As described above, the LTM operation configuration indicated through RRC signaling includes LTM candidate/target cell configuration, LTM radio bearer configuration, L1L2 signaling configuration for LTM operation, execution instruction information configuration for LTM operation, and TCI state configuration for LTM operation. and one or more of execution conditions/event configurations for LTM operation.

The above information includes L1L2 signaling configuration for LTM operation, execution instruction information configuration for LTM operation, TCI state configuration for LTM operation, execution condition/event configuration for LTM operation, triggering/starting/executing/applying LTM operation information can be displayed. The configuration may include information for associating the configuration with the LTM candidate/target cell configuration and/or the LTM radio bearer configuration. One LTM candidate/target cell configuration may be configured to be mapped one-to-one with the corresponding configuration. Alternatively, one LTM candidate/target cell configuration may be configured to be mapped one-to-many with one or more corresponding configurations.

Before cell change/handover is triggered/initiated/executed/applied based on L1L2 signaling/execution instruction information/TCI status/execution condition/event/related procedure/operation, the terminal does not include the LTM operation configuration If a handover command (RRC reconfiguration with sync) is received (or for normal handover, not for LTM operation), the terminal follows the received handover configuration regardless of any previously received LTM operation configuration. A handover procedure (according to the standard specification described in TS 38.300 Section 9.2.3.2) may be performed. When the UE receives the corresponding command, when the UE successfully completes the random access procedure for the corresponding cell, when the UE successfully completes handover, when the UE sends an RRC reconfiguration complete message to the target cell, the UE Stored LTM operation configuration/terminal variables can be released/removed.

Before cell change / handover is triggered / initiated / executed / applied based on L1L2 signaling / execution instruction information / TCI state / execution condition / event / related procedure / operation, the terminal includes the LTM operation configuration Upon receiving the RRC reconfiguration message, some or all of the configuration included in the corresponding configuration may be replaced/modified/changed/reconfigured/saved/applied. For example, LTM candidate/target cell configuration, LTM radio bearer configuration, L1L2 signaling configuration for LTM operation, and execution instructions for LTM operation through information for identifying the corresponding LTM operation configuration (or detailed configuration included in the corresponding configuration). One or more of information configuration, TCI state configuration for LTM operation, and execution condition/event configuration for LTM operation may be changed/modified.

Before cell change/handover is triggered/initiated/executed/applied based on L1L2 signaling/execution instruction information/TCI status/execution condition/event/related procedure/operation, the handover command (RRC reconfiguration with sync ), the corresponding handover command (or corresponding RRC reconfiguration message) may include LTM configuration for LTM operation in the corresponding target cell. The terminal may perform a handover procedure (according to the standard specification described in TS 38.300 Section 9.2.3.2) according to the received general handover configuration. The terminal may release/remove the LTM configuration/terminal variables configured/stored in the source cell. The terminal sets the target cell that has performed the handover as the cell/serving cell associated with the source cell/1TRP/1st TRP, and assigns any cell having a different PCI to the target cell/candidate cell/2nd TRP/2nd TRP. It is possible to store/apply an LTM operation configuration of an associated cell/non-serving cell. Through one RRC signaling message, it is possible to perform cell change and storage/application of the LTM operation configuration in the changed cell.

A major scenario of L1/L2 based LTM operation includes cell change within an intra CU. In this case, the logical node hosting the RRC/SDAP/PDCP protocols of the base station is the same. And the cell change scenario in the intra DU has the same MAC entity of the base station. When L1/L2 signaling-based LTM operation is performed within an Intra CU (Intra DU), it may be possible to transmit and receive data in a target cell by using/maintaining/reconfiguring the source cell configuration (or part of the configuration).

For example, cell change may be performed while using/maintaining one or more of a configured/applied cell group configuration and/or radio bearer configuration (similar to SCell change) in the source cell group. It is possible to have the source cell group perform cell change without performing one or more of security key refresh/change, random access to target cell/PCell, MAC reset, RLC reset, and PDCP reset/data recovery (similar to SCell change). there is. For another example, the UE may transmit/receive data from the target cell through a corresponding L2 entity (e.g. MAC/RLC/PDCP/SDAP) without changing the source cell configuration (or part of the configuration).

For another example, based on the TCI state activated in the source cell, data may be transmitted and received in the target cell using the same configuration as the source cell. According to the LTM radio bearer type, when cell change is performed from the source cell/1TRP/1st TRP linked cell/serving cell to the target cell/candidate cell/2TRP/2nd TRP linked cell/Non-serving cell without MAC reset ( Alternatively, the MAC procedure may be performed without performing all operations for the MAC entity through reset, and if necessary, only the corresponding operation is defined).

For another example, the MAC entity in the source cell/first TRP/first TRP associated cell/serving cell and target cell/candidate cell/second TRP/second TRP associated cell/Non-serving cell according to the radio bearer type for LTM operation It can be reconfigured/set/maintained to have the same configuration. Alternatively, (even if some operations related to MAC reset are performed), the specific operation/parameter being used/applied in the source cell/1TRP/1st TRP linked cell/serving cell is transferred to the target cell/candidate cell/2nd TRP/2nd TRP linked cell/ It can be used/applied continuously/maintained in the non-serving cell. Alternatively, only some of the following MAC reset-related operations linked to the source cell/first TRP/first TRP linked cell/serving cell may be performed. For example, one or more of the following operations related to MAC reset may not be performed.

For another example, when cell change/handover is triggered/initiated/executed/applied based on L1L2 signaling/execution instruction information/TCI status/execution conditions/events/related procedures/actions, or execution conditions configured in the terminal /When an execution condition is satisfied by evaluating an event, or when a specific procedure/action (e.g. measurement, event detection, condition satisfaction, TCI status update application, etc.) is performed in the terminal according to L1/L2 signaling reception and corresponding configuration , or when receiving L1/L2 signaling for triggering/initiating/executing/applying an LTM operation, or when instructing an LTM operation trigger/initiation/execution/application from a lower layer to an upper layer, a lower layer (e.g. PHY) When a corresponding operation of the MAC entity is requested from a higher layer (e.g. RRC), the MAC entity of the terminal may perform only some of the following MAC reset-related operations. Alternatively, the MAC entity of the UE may not perform one or more. Alternatively, the MAC entity of the terminal may define and perform one or more differently.

- (for the Bj parameter used for the logical channel priority procedure), initialize Bj to 0 for each logical channel

- stop all timers (if running)

- consider timeAlignmentTimers expired

- Set NDIs for the uplink HARQ process to a value of 0

- If there is a random access procedure in progress, stop it

- If present, discard explicitly signaled contention-free Random Access Resources for 4-step RA type and 2-step RA type

- Flush the Msg3/MSGA buffer

- if present, cancel the triggered scheduling request procedure

- if present, cancel the triggered buffer status reporting procedure

- Cancel the triggered power headroom reporting procedure, if present

- Cancel the triggered BFR if it exists

- Cancel the triggered Configured uplink grant confirmation if present

- Flush soft buffer for all DL HARQ processes

- For each DL HARQ process, consider the next received transmission for one TB as the first transmission (for each DL HARQ process, consider the next received transmission for a TB as the very first transmission)

- Release Temporary C-RNTI if present

- Reset BFI_COUNTERs

For convenience of explanation, an operation/procedure that does not perform all/partial operations performed by a MAC entity for MAC reset in a cell change process, or an operation/procedure that performs some operations differently, or a MAC performed for an LTM operation Mark the action/procedure as partial MAC reset. This is for convenience of description and can be replaced with any other name (e.g. MAC configuration, MAC reset, MAC maintenance, MAC switching, MAC reconfiguration, MAC restart, LTM MAC procedure, etc.).

For example, the corresponding procedure may not reset (or maintain) parameters related to the data processing procedure (when performing the LTM operation through the same MAC entity). Alternatively, the corresponding procedure may reset parameters related to the random access procedure/beam failure procedure.

For another example, the corresponding procedure may separately include the HARQ entity for the source cell and the HARQ entity for the target cell (when performing the LTM operation through the same MAC entity). The corresponding procedure may add HARQ entities for the target cell/candidate cell/2nd TRP/2nd TRP linked cell/Non-serving cell. Alternatively, the corresponding procedure may add cells for the target cell/candidate cell/second TRP/second TRP linked cell/Non-serving cell. For example, in the corresponding procedure, a cell configuration for a corresponding target cell/candidate cell/second TRP/second TRP linked cell may be added and included in the cell group configuration. For another example, the corresponding procedure may include information for indicating that the corresponding cell is a target cell/candidate cell/second TRP/second TRP linked cell in the SCell configuration and configure/instruct the UE. For another example, in the corresponding procedure, the cell configuration for the target cell/candidate cell/second TRP/second TRP linked cell may be added and included in the corresponding MAC configuration (e.g. MAC-CellGroupConfig).

For another example (when the LTM operation is performed through two MAC entities), the MAC entities of the source cell/first TRP/first TRP linked cell/serving cell may not be reset. The corresponding MAC entity configuration may be maintained. A MAC entity for the target cell/candidate cell/2nd TRP/2nd TRP linked cell/Non-serving cell may be established.

For another example, during the LTM operation (or during an arbitrary period defined in the corresponding handover), the terminal variable Bj may be maintained.

For another example, the (full/partial) MAC timer may be maintained during the LTM operation or for any period defined in the corresponding handover.

For another example, during LTM operation or any period defined in that handover, if any, triggered Scheduling Request Procedure/Triggered Buffer Status Reporting Procedure/Triggered Power Headroom Reporting Procedure/Triggered BFR/Trigger Configured uplink grant confirmation can be maintained. For example, the corresponding procedure may be considered pending.

As described above, the present embodiments can effectively reduce delay that may occur when changing a cell by providing a specific configuration and signaling method for controlling mobility based on L1/L2 for a UE.

Hereinafter, the configuration of a terminal and a base station capable of performing all or part of the above-described embodiments of the present disclosure will be described with reference to the drawings.

14 is a diagram showing a configuration of a terminal according to another embodiment.

Referring to FIG. 14, a terminal 1400 performing a cell change operation includes a receiver 1430 that receives a higher layer message including one or more candidate target cell configuration information for an LTM (L1/L2-triggered mobility) operation and A transmitter 1420 that transmits an L1 measurement result for a candidate target cell based on a higher layer message and a controller that performs a cell change operation without RRC reconfiguration by applying candidate target cell configuration information for the target cell based on the MAC CE ( 1410) may be included.

The receiving unit 1430 may further receive a Medium Access Control Control Element (MAC CE) indicating execution of an LTM operation on a target cell.

For example, the receiving unit 1430 may receive an RRC message including one or more candidate target cell configuration information from the base station or the TRP. The RRC message may include one or more candidate target cell configuration information, and each candidate target cell configuration information may be separately included for each candidate target cell.

For example, the higher layer message may include at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. The cell group configuration information includes information for configuring a cell group using two or more cells. Identification information on candidate target cell configuration information may include ID or index information. Through this, the terminal can distinguish each candidate target cell configuration information. The bandwidth part identification information may include an ID or index for identifying the bandwidth part (BWP). The TCI state configuration information may include at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI).

Meanwhile, candidate target cell configuration information includes information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. For example, the control unit 1410 controls an operation of measuring a channel state of a serving cell or a candidate target cell using candidate target cell configuration information. The transmitter 1420 transmits the measured channel state or channel quality information to the base station based on the measurement result transmission information included in the candidate target cell configuration information. For example, the transmitter 1420 may transmit the measurement result to the base station based on the information for transmission of the measurement result included in the candidate target cell configuration information. For example, the transmitter 1420 may transmit the measurement result of the corresponding serving cell or candidate target cell to the base station when a condition for triggering transmission of the measurement result is satisfied. As another example, L1 measurement result transmission is triggered when the quality of the measurement result of the candidate target cell is higher than the measurement result of the source PSCell obtained by adding or subtracting an offset. That is, when comparing the measurement result of the source PSCell with the measurement result of the candidate target cell, the measurement result of the source PSCell is compared by adding or subtracting an offset included in the preset or candidate target cell configuration information. If the comparison results show that the candidate target cell has a better channel state, reporting on the measurement result may be triggered.

In addition, the receiving unit 1430 may receive instruction information indicating execution of the LTM operation included in the MAC CE. As another example, the receiving unit 1430 may check information on a target cell included in the MAC CE and receive an LTM operation execution instruction for the target cell. Through the MAC CE, the control unit 1410 needs to obtain an LTM operation instruction and information on a target cell to perform cell change. To this end, the MAC CE may include at least one of identification information for candidate target cell configuration information, a TCI state ID, bandwidth part identification information, and a timing advance command. For example, the MAC CE may include identification information for distinguishing candidate target cell configuration information configured in the terminal through a higher layer message. Identification information may be composed of candidate target cell configuration information ID or index information. In addition, the MAC CE may include at least one of a TCI state ID, a bandwidth part ID, and a TAG.

In addition, when the MAC CE is received, the controller 1410 can identify a target cell for performing cell change based on the corresponding MAC CE. For example, the controller 1410 checks identification information on candidate target cell configuration information included in the MAC CE, and checks candidate target cell configuration information assigned to the corresponding identification information and received through a higher layer message. A candidate target cell to which the corresponding candidate target cell configuration information is applied may become a target cell for cell change. That is, identification information assigned to one or more candidate target cell configuration information received through higher layer messages and identification information assigned to candidate target cell configuration information received through MAC CE may be the same. Through this, the control unit 1410 can identify the target cell through the MAC CE.

When the target cell is identified, the controller 1410 applies candidate target cell configuration information applied to the corresponding target cell to the terminal. In addition, the controller 1410 performs a cell change operation to a target cell using candidate target cell configuration information of the target cell without performing an RRC reconfiguration operation.

Meanwhile, the controller 1410 may store/apply one or more candidate target cell configuration information to the terminal until higher layer signaling for releasing the candidate target cell configuration information is received. For example, when a plurality of candidate target cell configuration information is received through a higher layer message, the control unit 1410 completes the cell change to the corresponding target cell by applying any one candidate target cell configuration information through the aforementioned MAC CE. can do. The controller 1410 can still maintain the plurality of candidate target cell configuration information effectively even after the cell change is completed. Accordingly, if MAC CE indicating an LTM operation is received again from the base station after cell change, the control unit 1410 effectively uses the stored candidate target cell configuration information to perform a cell change operation. That is, release, change, addition, etc. of candidate target cell configuration information configured/stored in the terminal can be performed only by separate higher layer signaling for this purpose.

In addition to this, the transmission unit 1420 and the reception unit 1430 are used to transmit and receive signals, messages, and data necessary for performing the present embodiments described above with the base station. In addition, the control unit 1410 controls overall operations of the terminal 1400 necessary to perform the present embodiments described above.

15 is a diagram showing the configuration of a base station according to another embodiment

Referring to FIG. 15, a base station 1500 controlling a cell change operation of a terminal includes a transmitter 1520 that transmits a higher layer message including one or more candidate target cell configuration information for LTM (L1/L2-triggered mobility) operation. ) and a receiving unit 1530 for receiving the L1 measurement result for the candidate target cell and a control unit 1510 for determining whether to perform the LTM operation for the target cell based on the L1 measurement result.

The transmitter 1520 may further transmit a Medium Access Control Control Element (MAC CE) indicating execution of an LTM operation to a target cell.

For example, the transmitter 1520 may transmit an RRC message including one or more candidate target cell configuration information to the terminal. The RRC message may include one or more candidate target cell configuration information, and each candidate target cell configuration information may be separately included for each candidate target cell. For example, the higher layer message may include at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. The cell group configuration information includes information for configuring a cell group using two or more cells. Identification information on candidate target cell configuration information may include ID or index information. Through this, the terminal can distinguish each candidate target cell configuration information. The bandwidth part identification information may include an ID or index for identifying the bandwidth part (BWP). The TCI state configuration information may include at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI).

Meanwhile, candidate target cell configuration information includes information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. For example, the terminal measures the channel state of the serving cell or the candidate target cell using candidate target cell configuration information. The terminal transmits the measured channel state or channel quality information to the base station based on the information for transmitting the measurement result included in the candidate target cell configuration information. To this end, information for measurement reporting may be included in candidate target cell configuration information.

The receiving unit 1530 receives the measurement result reporting including the L1 measurement result transmitted by the terminal. For example, the terminal may transmit the measurement result to the base station 1500 based on the information for transmission of the measurement result included in the candidate target cell configuration information. For example, the terminal may transmit the measurement result of the corresponding serving cell or candidate target cell to the base station when the condition for triggering transmission of the measurement result is satisfied. As another example, L1 measurement result transmission is triggered when the quality of the measurement result of the candidate target cell is higher than the measurement result of the source PSCell obtained by adding or subtracting an offset.

In addition, the controller 1510 may determine whether to perform the LTM operation based on the L1 measurement result information of the terminal. As another example, the controller 1510 may determine a target cell to be changed through the LTM operation based on the L1 measurement result information of the UE. As such, the control unit 1510 may perform an LTM operation for the UE and determine a target cell to be changed by the UE based on the L1 measurement result received from the UE.

When the transmitter 1520 determines cell change of the corresponding terminal based on the L1 measurement result information received from the terminal, it may indicate this through the MAC CE.

For example, the transmitter 1520 may include and transmit instruction information instructing the MAC CE to perform the LTM operation. As another example, the transmitter 1520 may include and transmit information about the target cell to the MAC CE.

Through the MAC CE, the terminal can obtain an instruction for performing an LTM operation and information on a target cell to perform cell change. For example, the MAC CE may include at least one of identification information for candidate target cell configuration information, a TCI state ID, bandwidth part identification information, and a timing advance command. For example, the MAC CE may include identification information for distinguishing candidate target cell configuration information configured in the terminal through a higher layer message.

For example, when the MAC CE is received, the UE can identify a target cell for performing cell change based on the corresponding MAC CE. For example, the terminal checks identification information on candidate target cell configuration information included in the MAC CE, and checks candidate target cell configuration information assigned to the corresponding identification information and received through a higher layer message. A candidate target cell to which the corresponding candidate target cell configuration information is applied may become a target cell for cell change. When a target cell is identified, the terminal applies candidate target cell configuration information applied to the corresponding target cell to the terminal. In addition, the terminal performs a cell change operation to the target cell using candidate target cell configuration information of the corresponding target cell without performing the RRC reconfiguration operation.

Meanwhile, one or more candidate target cell configuration information may be stored and applied to the UE until higher layer signaling for releasing the candidate target cell configuration information is received. The transmitter 1520 may transmit to the terminal separate higher layer signaling for instructing release, change, addition, etc. of candidate target cell configuration information configured/stored in the terminal.

In addition to this, the transmission unit 1520 and the reception unit 1530 are used to transmit and receive signals, messages, and data necessary for performing the present embodiments described above to and from the terminal. In addition, the control unit 1510 controls overall operations of the base station 1500 necessary to perform the present embodiments described above.

The above-described embodiments may be supported by standard documents disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, which are wireless access systems. That is, among the present embodiments, steps, configurations, and parts not described to clearly reveal the present technical idea may be supported by the above-mentioned standard documents. In addition, all terms disclosed in this specification can be explained by the standard documents disclosed above.

The present embodiments described above may be implemented through various means. For example, the present embodiments may be implemented by hardware, firmware, software, or a combination thereof.

In the case of hardware implementation, the method according to the present embodiments includes one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, or microprocessors.

In the case of implementation by firmware or software, the method according to the present embodiments may be implemented in the form of a device, procedure, or function that performs the functions or operations described above. The software codes may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor and exchange data with the processor by various means known in the art.

Also, the terms "system", "processor", "controller", "component", "module", "interface", "model", or "unit" as described above generally refer to computer-related entities hardware, hardware and software. can mean a combination of, software or running software. For example, but is not limited to, a process driven by a processor, a processor, a controller, a control processor, an object, a thread of execution, a program, and/or a computer. For example, a component can be both an application running on a controller or processor and a controller or processor. One or more components may reside within a process and/or thread of execution, and components may reside on one device (eg, system, computing device, etc.) or may be distributed across two or more devices.

The above description is merely illustrative of the technical idea of the present disclosure, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the technical idea. In addition, since the present embodiments are not intended to limit the technical idea of the present disclosure, but to explain, the scope of the present technical idea is not limited by these embodiments. The scope of protection of the present disclosure should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of the present disclosure.

Claims (24)

In the method for the terminal to perform a cell change operation,
Receiving a higher layer message including one or more candidate target cell configuration information for an L1/L2-triggered mobility (LTM) operation;
Transmitting an L1 measurement result for a candidate target cell based on the higher layer message;
Receiving a Medium Access Control Control Element (MAC CE) indicating execution of the LTM operation to a target cell; and
and performing a cell change operation without RRC reconfiguration by applying the candidate target cell configuration information for the target cell based on the MAC CE. According to claim 1,
The upper layer message,
A method including at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. According to claim 2,
The TCI state configuration information,
A method including at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI). According to claim 1,
The candidate target cell configuration information,
A method including information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. According to claim 1,
Transmission of the L1 measurement result,
A method that is triggered when the measurement result of the candidate target cell has a higher quality than a value obtained by adding or subtracting an offset to the measurement result of the source PSCell. According to claim 1,
The MAC CE,
A method including at least one of identification information for candidate target cell configuration information, TCI state ID, bandwidth part identification information, and timing advance command. According to claim 1,
The candidate target cell configuration information,
characterized in that it is applied until higher layer signaling for releasing the candidate target cell configuration information is received. In the method for the base station to control the cell change operation of the terminal,
Transmitting a higher layer message including one or more candidate target cell configuration information for L1/L2-triggered mobility (LTM) operation;
Receiving an L1 measurement result for a candidate target cell;
determining whether to perform the LTM operation for a target cell based on the L1 measurement result; and
Transmitting a Medium Access Control Control Element (MAC CE) indicating execution of the LTM operation to the target cell. According to claim 8,
The upper layer message,
A method including at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. According to claim 9,
The TCI state configuration information,
A method including at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI). According to claim 8,
The candidate target cell configuration information,
A method including information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. According to claim 8,
The MAC CE,
A method including at least one of identification information for candidate target cell configuration information, TCI state ID, bandwidth part identification information, and timing advance command. In a terminal performing a cell change operation,
a receiving unit receiving a higher layer message including one or more candidate target cell configuration information for L1/L2-triggered mobility (LTM) operation;
a transmitter for transmitting an L1 measurement result for a candidate target cell based on the higher layer message; and
A control unit performing a cell change operation without RRC reconfiguration by applying the candidate target cell configuration information for a target cell based on MAC CE;
The receiving unit receives the MAC CE (Medium Access Control Control Element) instructing to perform the LTM operation to the target cell. According to claim 13,
The upper layer message,
A terminal including at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. 15. The method of claim 14,
The TCI state configuration information,
A terminal including at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI). According to claim 13,
The candidate target cell configuration information,
A terminal including information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. According to claim 13,
Transmission of the L1 measurement result,
A UE triggered when the measurement result of the candidate target cell has a higher quality than a value obtained by adding or subtracting an offset to the measurement result of the source PSCell. According to claim 13,
The MAC CE,
A terminal including at least one of identification information for candidate target cell configuration information, a TCI state ID, bandwidth part identification information, and a timing advance command. According to claim 13,
The candidate target cell configuration information,
The terminal characterized in that it is applied until higher layer signaling for releasing the candidate target cell configuration information is received. In the base station for controlling the cell change operation of the terminal,
a transmitter for transmitting a higher layer message including one or more candidate target cell configuration information for L1/L2-triggered mobility (LTM) operation;
a receiving unit receiving an L1 measurement result for a candidate target cell; and
A control unit for determining whether to perform the LTM operation for a target cell based on the L1 measurement result,
The transmitting unit transmits a Medium Access Control Control Element (MAC CE) indicating execution of the LTM operation to the target cell. 21. The method of claim 20,
The upper layer message,
A base station including at least one of cell group configuration information, identification information for candidate target cell configuration information, bandwidth part identification information, and TCI (Transmission Configuration Indication) state configuration information. According to claim 21,
The TCI state configuration information,
A base station including at least one of a TCI state ID, a cell index, a cell ID, and a physical cell identity (PCI). 21. The method of claim 20,
The candidate target cell configuration information,
A base station including information for performing L1 measurement on a serving cell or candidate target cell and transmission of the L1 measurement result. 21. The method of claim 20,
The MAC CE,
A base station including at least one of identification information for candidate target cell configuration information, TCI state ID, bandwidth part identification information, and a timing advance command.

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