Method for time alignment in wireless communication system and apparatus therefor

Abstract

According to one embodiment of the present specification, a method performed by a terminal comprises the steps of: receiving configuration information related to a timing advance group (TAG) from a base station; performing an operation related to maintaining uplink timing alignment based on the time alignment timer; and transmitting an uplink channel / signal to the base station based on the uplink transmission timing for the TAG.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for time alignment in a wireless communication system. Background Art

[0002] Mobile communication systems have evolved to provide voice services while ensuring user activity. Mobile communication systems are expanding their services from voice only to data. The current surge in data traffic is exhausting resources, and user demand for higher data rate services brings the need for more advanced mobile communication systems.

[0003] The next generation of mobile communication systems needs to meet requirements such as handling the explosive growth of data traffic, significantly increasing the transmission rate for each user, working with a large number of connected devices, and supporting very low end-to-end latency and high energy efficiency. To this end, various research efforts are being conducted on various technologies, such as dual connectivity, massive multiple-input multiple-output (MIMO), in-band full-duplex, non-orthogonal multiple access (NOMA), ultra-wideband support, and device networking.

[0004] In the existing LTE and NR standards, in the uplink timing advance configuration / indication, a single timing advance (TA) value is supported for a timing advance group (TAG) to which a specific cell or cell group belongs.

[0005] In an environment where there is a large distance difference between the UE and different transmission and reception points (TRPs), multi-DCI-based multiple transmission and reception point (M-DCI-based M-TRP) operation can be performed. In this case, propagation delay differences, slot boundary differences, and inter-UE panel delay differences may occur between target TRPs for uplink transmission within a CC / BWP. In particular, this phenomenon may occur to a greater extent in non-ideal backhaul operations where no coordination is performed between TRPs.

[0006] As described above, in order to compensate for the timing differences or delays that occur between TRPs, it is necessary to determine the uplink timing differently for each TRP. To this end, it has been agreed that the operation of connecting / corresponding the TAG to the TCI state of a unified TCI (e.g., a joint TCI state, a separate TCI state (DL TCI state or UL TCI state)) has been performed. Summary of the invention

[0007] Technical issues

[0008] When using time alignment timers associated with multiple TAGs, according to existing schemes, ambiguity may occur in uplink time alignment maintenance operations. For example, an operation of releasing UL / DL configuration (e.g., a release operation of PUCCH / SRS, a configured DL / UL assignment, UL authorization, and a clearing operation of PUSCH resources) is performed based on the expiration of a time alignment timer associated with a TAG (PTAG). At this time, it is unclear whether the operation is performed based on the expiration of any timer among the multiple timers (e.g., i) the expiration of each timer, ii) the expiration of a specific timer among the multiple timers, or iii) the expiration of all timers).

[0009] Furthermore, since releasing all UL configurations (eg, PUCCH configurations) will disable HARQ-ACK transmission for DL ​​reception (from all serving cells), if this release operation is performed frequently, it will affect DL operations as well as UL operations.

[0010] The purpose of the present disclosure is to propose a method to resolve ambiguity in operations related to time alignment timer expiration when maintaining time alignment based on TRP-specific TA, and minimize the impact of such operations on UL / DL.

[0011] The technical objectives to be achieved by the present disclosure are not limited to those described above only by way of example, and other technical objectives not mentioned can be clearly understood from the following description by those skilled in the art to which the present disclosure pertains.

[0012] Technical Solution

[0013] According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system includes: receiving configuration information related to a timing advance group (TAG) from a base station, performing operations related to maintaining uplink timing alignment based on a time alignment timer, and sending an uplink channel / signal to the base station based on uplink transmission timing for the TAG. The configuration information includes information for a time alignment timer related to the TAG.

[0014] The TAG includes a first TAG and a second TAG belonging to a serving cell. The configuration information includes information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. Each TAG is a primary TAG (PTAG) or a secondary TAG (STAG).

[0015] Based on the expiration of the first time alignment timer and the second time alignment timer, perform the following operations: i) flush all HARQ buffers, ii) release the configured physical uplink control channel (PUCCH), iii) release the configured sounding reference signal (SRS), iv) clear the configured downlink assignment and the configured uplink grant, v) clear the physical uplink shared channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) maintain N per TAG TA .

[0016] Based on expiration of the first time alignment timer and the second time alignment timer, uplink transmission other than random access preamble transmission and MsgA transmission may not be performed.

[0017] The method may also include receiving configuration information associated with a plurality of control resource sets (CORESETs).The CORESET based on the first CORESET pool index and the second CORESET pool index may be configured based on the configuration information associated with the CORESET.

[0018] The first TAG may be associated with a first CORESET pool index, and the second TAG may be associated with a second CORESET pool index.

[0019] The method may further include: based on expiration of the first time alignment timer or the second time alignment timer, sending information related to the expired time alignment timer.

[0020] Information related to the expired time alignment timer may include at least one of the following: i) an ID of the first TAG or the second TAG, ii) a first CORESET pool index associated with the first TAG or a second CORESET pool index associated with the second TAG, and / or iii) an ID of a transmit and receive point (TRP) associated with the first TAG or the second TAG.

[0021] Information related to an expired time alignment timer may be sent based on the first uplink resource or the second uplink resource. The first uplink resource may be related to the expiration of the first time alignment timer, and the second uplink resource may be related to the expiration of the second time alignment timer. The first uplink resource may be related to the second CORESET pool index, and the second uplink resource may be related to the first CORESET pool index.

[0022] The uplink channel / signal may include i) a first uplink channel / signal transmitted based on uplink timing for a first TAG and / or ii) a second uplink channel / signal transmitted based on uplink timing for a second TAG.

[0023] The first uplink channel / signal may be i) a first PUSCH, ii) a first PUCCH, or iii) a first SRS, and the second uplink channel / signal may be i) a second PUSCH, ii) a second PUCCH, or iii) a second SRS.

[0024] Based on expiration of the first time alignment timer or the second time alignment timer, the first uplink channel / signal or the second uplink channel / signal may be dropped.

[0025] The method may also include: based on i) the first time alignment timer or the second time alignment timer expires, and ii) the first uplink channel / signal and the second uplink channel / signal are transmitted, receiving a timing advance command medium access control (MAC) control element (CE) (MAC CE). The timing advance command MAC CE may be related to the first TAG or the second TAG.

[0026] The method may further include receiving downlink control information (DCI) based on i) expiration of the first time alignment timer or the second time alignment timer, and ii) the first uplink channel / signal and the second uplink channel / signal being transmitted.

[0027] The DCI may include information related to a physical downlink control channel (PDCCH) order. A random access procedure may be initiated by a PDCCH order.

[0028] Based on the expiration of the first time alignment timer or the second time alignment timer, the uplink channel / signal may be the second uplink channel / signal or the first uplink channel / signal.

[0029] Based on the first TAG being the first PTAG and the second TAG being the second PTAG, operations i) to vi) performed based on the expiration of the first time alignment timer and the second time alignment timer may be performed for all serving cells, and all running time alignment timers may be considered expired.

[0030] Based on the first TAG being the first STAG and the second TAG being the second STAG, operations i) to vi) performed based on expiration of the first time alignment timer and the second time alignment timer may be performed on a serving cell belonging to the first STAG and a serving cell belonging to the second STAG.

[0031] The uplink channel / signal may be transmitted regardless of whether the timing difference between the first TAG and the second TAG exceeds the maximum uplink transmission timing difference associated with the stop of uplink transmission.

[0032] N TA May be related to the calculation of Timing Advance (TA).

[0033] The serving cell may be a special cell (SpCell) or a secondary cell (SCell).

[0034] Based on the expiration of the first time alignment timer or the second time alignment timer, at least one operation of operations i) to vi) may be performed.

[0035] According to another embodiment of the present disclosure, a user equipment (UE) operating in a wireless communication system includes one or more transceivers, one or more processors, and one or more memories operably connected to the one or more processors, and the one or more memories store instructions that configure the one or more processors to perform operations based on execution by the one or more processors.

[0036] The operations include receiving configuration information related to a timing advance group (TAG) from a base station, performing operations related to maintaining uplink timing alignment based on a time alignment timer, and sending an uplink channel / signal to the base station based on uplink transmission timing for the TAG. The configuration information includes information for a time alignment timer related to the TAG.

[0037] The TAG includes a first TAG and a second TAG belonging to a serving cell. The configuration information includes information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. Each TAG is a primary TAG (PTAG) or a secondary TAG (STAG).

[0038] Based on the expiration of the first time alignment timer and the second time alignment timer, perform the following operations: i) flush all HARQ buffers, ii) release the configured physical uplink control channel (PUCCH), iii) release the configured sounding reference signal (SRS), iv) clear the configured downlink assignment and the configured uplink grant, v) clear the physical uplink shared channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) maintain N per TAG TA .

[0039] A device according to another embodiment of the present disclosure includes one or more memories and one or more processors functionally connected to the one or more memories.

[0040] The one or more memories include instructions that, upon execution by the one or more processors, configure the one or more processors to perform operations.

[0041] The operations include receiving configuration information related to a timing advance group (TAG) from a base station, performing operations related to maintaining uplink timing alignment based on a time alignment timer, and sending an uplink channel / signal to the base station based on uplink transmission timing for the TAG. The configuration information includes information for a time alignment timer related to the TAG.

[0042] The TAG includes a first TAG and a second TAG belonging to a serving cell. The configuration information includes information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. Each TAG is a primary TAG (PTAG) or a secondary TAG (STAG).

[0043] Based on the expiration of the first time alignment timer and the second time alignment timer, perform the following operations: i) flush all HARQ buffers, ii) release the configured physical uplink control channel (PUCCH), iii) release the configured sounding reference signal (SRS), iv) clear the configured downlink assignment and the configured uplink grant, v) clear the physical uplink shared channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) maintain N per TAG TA .

[0044] According to another embodiment of the present disclosure, one or more non-transitory computer-readable media store one or more instructions.

[0045] The one or more instructions executable by the one or more processors configure the one or more processors to perform operations.

[0046] The operations include receiving configuration information related to a timing advance group (TAG) from a base station, performing operations related to maintaining uplink timing alignment based on a time alignment timer, and sending an uplink channel / signal to the base station based on uplink transmission timing for the TAG. The configuration information includes information for a time alignment timer related to the TAG.

[0047] The TAG includes a first TAG and a second TAG belonging to a serving cell. The configuration information includes information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. Each TAG is a primary TAG (PTAG) or a secondary TAG (STAG).

[0048] Based on the expiration of the first time alignment timer and the second time alignment timer, perform the following operations: i) flush all HARQ buffers, ii) release the configured physical uplink control channel (PUCCH), iii) release the configured sounding reference signal (SRS), iv) clear the configured downlink assignment and the configured uplink grant, v) clear the physical uplink shared channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) maintain N per TAG TA .

[0049] According to another embodiment of the present disclosure, a method performed by a base station in a wireless communication system includes: sending configuration information related to a timing advance group (TAG) to a user equipment (UE), and receiving an uplink channel / signal from the UE based on an uplink transmission timing for the TAG.

[0050] The configuration information includes information about a time alignment timer associated with the TAG. The UE performs operations related to maintaining uplink timing alignment based on the time alignment timer.

[0051] The TAG includes a first TAG and a second TAG belonging to a serving cell. The configuration information includes information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. Each TAG is a primary TAG (PTAG) or a secondary TAG (STAG).

[0052] Based on the expiration of the first time alignment timer and the second time alignment timer, the UE performs the following operations: i) flushes all HARQ buffers, ii) releases the configured physical uplink control channel (PUCCH), iii) releases the configured sounding reference signal (SRS), iv) clears the configured downlink assignments and configured uplink grants, v) clears the physical uplink shared channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) maintains N per TAG. TA .

[0053] According to another embodiment of the present disclosure, a base station operating in a wireless communication system includes: one or more transceivers, one or more processors, and one or more memories, wherein the one or more memories are operably connected to the one or more processors and store instructions that configure the one or more processors to perform operations based on execution by the one or more processors.

[0054] The operations include: transmitting configuration information related to a timing advance group (TAG) to a user equipment (UE), and receiving an uplink channel / signal transmitted based on uplink transmission timing for the TAG from the UE.

[0055] The configuration information includes information for a time alignment timer associated with the TAG. The UE performs operations related to maintenance of uplink timing alignment based on the time alignment timer.

[0056] The TAG includes a first TAG and a second TAG belonging to a serving cell. The configuration information includes information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. Each TAG is a primary TAG (PTAG) or a secondary TAG (STAG).

[0057] Based on the expiration of the first time alignment timer and the second time alignment timer, the UE performs the following operations: i) flushes all HARQ buffers, ii) releases the configured physical uplink control channel (PUCCH), iii) releases the configured sounding reference signal (SRS), iv) clears the configured downlink assignment and the configured uplink grant, v) clears the physical uplink shared channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) maintains N per TAG TA .

[0058] Beneficial Effects

[0059] According to an embodiment of the present disclosure, a release operation based on the expiration of a time alignment timer is performed in a restricted manner based on the expiration of multiple time alignment timers. Therefore, the ambiguity problem in UE / base station operation when performing an operation when an existing time alignment timer expires can be solved.

[0060] In addition, problems caused by frequent occurrence of UL / DL configuration release operations can be prevented. Specifically, i) an increase in signaling overhead due to UL / DL related reconfiguration of each serving cell can be prevented, and ii) a decrease in reliability of UL / DL operations can be prevented.

[0061] Effects that can be achieved by using the present disclosure are not limited to the effects described above by way of example only, and those skilled in the art to which the present disclosure belongs will more clearly understand other effects and advantages of the present disclosure from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 MAC RAR according to an embodiment of the present disclosure is illustrated.

[0063] Figure 2 A timing advance command MAC CE according to an embodiment of the present disclosure is illustrated.

[0064] Figure 3 is a flowchart illustrating a method performed by a UE in a wireless communication system according to an embodiment of the present disclosure.

[0065] Figure 4 is a flowchart illustrating a method performed by a base station in a wireless communication system according to another embodiment of the present disclosure.

[0066] Figure 5 The configurations of the first device and the second device according to the embodiment of the present disclosure are illustrated. DETAILED DESCRIPTION

[0067] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following detailed description in conjunction with the accompanying drawings is intended to describe embodiments of the present disclosure, but does not represent the only embodiment of the present disclosure. The following detailed description includes specific details to convey a thorough understanding of the present disclosure. However, it will be readily understood by those skilled in the art that embodiments of the present disclosure can be practiced even without these details.

[0068] In some cases, to avoid conceptual ambiguity, well-known structures or devices may be omitted or shown in block diagrams, while focusing on the core features of each structure and device.

[0069] In the following, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In the downlink, the sender may be part of a base station, and the receiver may be part of a terminal. In the uplink, the sender may be part of a terminal, and the receiver may be part of a base station. The base station may be represented as a first communication device, and the terminal may be represented as a second communication device. The base station (BS) may be replaced with terms including a fixed station, a node B, an evolved node B (eNB), a next generation node B (gNB), a base transceiver system (BTS), an access point (AP), a network (5G network), an AI system, a roadside unit (RSU), a vehicle, a robot, an unmanned aerial vehicle (UAV), an augmented reality (AR) device, a virtual reality (VR) device, and the like. In addition, the terminal may be fixed or mobile, and may be replaced by terms including user equipment (UE), mobile station (MS), user terminal (UT), mobile subscriber station (MSS), subscriber station (SS), advanced mobile station (AMS), wireless terminal (WT), machine type communication (MTC) device, machine to machine (M2M) device and device to device (D2D) device, vehicle, robot, AI module, unmanned aerial vehicle (UAV), augmented reality (AR) device, virtual reality (VR) device, etc.

[0070] Multiple transmit / receive point (M-TRP) related operations

[0071] The M-TRP transmission scheme in which M TRPs send data to one user equipment (UE) can be divided into two main types: eMBB M-TRP transmission is a scheme for increasing the transmission rate, and URLLC M-TRP transmission is a scheme for increasing the reception success rate and reducing the latency.

[0072] MTRP transmission based on SDCI or MDCI

[0073] From the perspective of downlink control information (DCI) transmission, the M-TRP (multi-TRP) transmission scheme can be divided into i) an M-TRP transmission scheme based on multiple DCI (M-DCI), in which each TRP sends different DCI and ii) an M-TRP transmission scheme based on single DCI (S-DCI), in which one TRP sends DCI.

[0074] R16NR MTRP Sent

[0075] The R16NR standard supports the MTRP PDSCH transmission scheme based on S-DCI and the MTRP PDSCH transmission scheme based on M-DCI.

[0076] MTRP PDSCH based on R16M-DCI

[0077] M-DCI-based MTRP PDSCH transmission is a method in which each TRP schedules and transmits PDSCH through DCI. That is, TRP 1 transmits PDSCH 1 through DCI 1, and TRP 2 transmits PDSCH 2 through DCI 2. When PDSCH1 and PDSCH 2 overlap in the same frequency-time resource, the two PDSCHs are received for the same RE, thereby improving resource efficiency and increasing transmission capacity. To this end, the R16 standard introduces a CORESET pool, which is a group of multiple CORESETs, and TRP 1 transmits PDCCH through a CORESET belonging to CORESET pool 0, and the PDSCH scheduled by the corresponding PDCCH is also transmitted by TRP1. TRP 2 transmits PDCCH through a CORESET belonging to CORESET pool 1, and the PDSCH scheduled by the corresponding PDCCH is also transmitted by TRP 2. For PUSCH, a specific TRP can schedule the transmission of PUSCH to the UE through a CORESET belonging to each CORESET pool. For PUCCH, TRP 1 schedules some PUCCH resources to receive UCI, and TRP 2 schedules the remaining PUCCH resources to receive UCI. For PUSCH or PUCCH, the channels scheduled / used by each TRP are TDMed with each other and do not overlap. Therefore, an increase in transmission capacity cannot be expected, but the UE can independently send PUSCH / PUCCH to each of TRP 1 and TRP 2.

[0078] In addition, the UE may identify a PUSCH (or PUCCH) scheduled by DCI and received by different CORESETs (or CORESETs belonging to different CORESET groups) as a PUSCH (or PUCCH) sent to different TRPs, or identify a PUSCH (or PUCCH) of a different TRP. The scheme for UL transmission (e.g., PUSCH / PUCCH) sent to different TRPs may also be applicable to UL transmission (e.g., PUSCH / PUCCH) sent to different panels belonging to the same TRP.

[0079] The CORESET group ID (or the COERSET pool index having the same meaning) described / mentioned in the present disclosure may mean an index / identification information (e.g., ID) and the like for distinguishing the CORESET for each TRP / panel. In addition, the CORESET group may be a group / union of CORESETs classified by index / identification information (e.g., ID) / CORESET group ID and the like for distinguishing the CORESET for each TRP / panel. For example, the CORESET group ID may be specific index information defined in the CORESET configuration. For example, the CORESET group may be configured / indicated / defined by an index defined in the CORESET configuration for each CORESET. And / or, the CORESET group ID may mean an index / identification information / indicator and the like for distinguishing / identifying the CORESET configured / associated to each TRP / panel, and the CORESET group ID described / mentioned in the present disclosure may be replaced and expressed with a specific index / specific identification information / specific indicator and the like for distinguishing / identifying the CORESET configured / associated to each TRP / panel. The CORESET group ID, i.e., a specific index / specific identification information / specific indicator for distinguishing / identifying the CORESET configured / associated to each TRP / panel, may be configured / indicated through high-layer signaling (e.g., RRC signaling) / L2 signaling (e.g., MAC-CE) / L1 signaling (e.g., DCI), etc. For example, PDCCH detection for each TRP / panel may be configured / indicated to be performed in units of the corresponding CORESET group, and / or uplink control information (e.g., CSI, HARQ-A / N, SR) and / or uplink physical channel resources (e.g., PUCCH / PRACH / SRS resources) may be configured / indicated to be managed / controlled individually for each TRP / panel in units of the corresponding CORESET group, and / or HARQ A / N (processing / retransmission), etc., for PDSCH / PUSCH scheduled for each TRP / panel may be managed in units of the corresponding CORESET group.

[0080] For example, the high-level parameter ControlResourceSet IE (information element) is used to configure the time / frequency control resource set (CORESET). For example, the control resource set (CORESET) may be related to the detection and reception of downlink control information. The ControlResourceSet IE may include a CORESET-related ID (e.g., controlResourceSetID) / an index of a CORESET pool for a CORESET (e.g., CORESETPoolIndex) / a time-frequency resource configuration of a CORESET / TCI information related to a CORESET, etc. For example, the index of a CORESET pool (e.g., CORESETPoolIndex) may be set to 0 or 1. In the specification, a CORESET group may correspond to a CORESET pool, and a CORESET group ID may correspond to a CORESET pool index (e.g., CORESETPoolIndex). The ControlResourceSet (i.e., CORESET) may be configured through high-level signaling (e.g., RRC).

[0081] Timing Advance (TA) Related Process

[0082] The uplink frame number i for transmission from a user equipment (UE) should be T before the start of the corresponding downlink frame at the UE. TA start.

[0083] With T TA The relevant uplink timing (such as uplink frame) can be based on the following Table 1.

[0084] [Table 1]

[0085]

[0086] In Table 1, T TA Can be based on N TA and N TA,offset To calculate / determine. N TA and N TA,offset It can be configured / applied as follows.

[0087] N TA : 1) configured by random access response (RAR) and 2) configured by timing advance command (MAC-CE);

[0088] N TA,offset : 1) configure specific values ​​per serving cell and 2) apply predefined values ​​based on duplex mode / FR appropriately to the serving cell.

[0089] The following describes the above configuration / application in detailTA,offset and N TA method.

[0090] N TA,offset

[0091] Case 1) Method for configuring specific values ​​by serving cell

[0092] For example, the UE may receive a message including information about N TA,offset The configuration information (eg, ServingCellConfigCommon information) of the information. The configuration information may be received based on RRC signaling. The following Table 2 shows the configuration information.

[0093] [Table 2]

[0094]

[0095]

[0096] Case 2) Method of appropriately applying predefined values ​​based on duplex mode / FR to serving cell

[0097] For example, the UE can use the predefined N based on the duplex mode (TDD / FDD) / FR TA,offset The value is appropriately applied to the serving cell. Table 3 below shows N TA,offset The value of .

[0098] [Table 3]

[0099]

[0100] N TA

[0101] Case 1) Configuration method through random access response (RAR)

[0102] For example, in a random access procedure (eg, a 2-step RACH procedure or a 4-step RACH procedure), the UE may receive a RAR from the base station. The N may be determined / configured based on the RAR. TA Specifically, the RAR may include a timing advance command. The timing advance command indicates an index value (eg, index value TA) related to the timing adjustment. N may be determined based on the index value. TA (See Table 5 below). RAR can be based on MAC RAR. This will be referred to below Figure 1 Give a description.

[0103] Figure 1 MAC RAR according to an embodiment of the present disclosure is illustrated.

[0104] Reference Figure 1, MAC RAR may include a reserved bit R, a timing advance command, a UL grant, and a temporary C-RNTI. Table 4 below shows the MAC payload of MAC RAR.

[0105] [Table 4]

[0106]

[0107] Table 5 below shows the transmission timing adjustment based on the timing advance command.

[0108] [Table 5]

[0109]

[0110] Case 2) Configuration via Timing Advance Command (MAC-CE)

[0111] For example, N can be determined / configured based on MAC-CE. TA Specifically, N can be determined based on the timing advance command MAC CE. TA The timing advance command MAC CE may include a timing advance command. Since N is determined based on the timing advance command TA Same as described in case 1, so repeated description is omitted (see Table 5). Figure 2 To describe the timing advance command MACCE.

[0112] Figure 2 A timing advance command MAC CE according to an embodiment of the present disclosure is illustrated.

[0113] Reference Figure 2 , the timing advance command MAC CE may include a TAG ID and a timing advance command. Table 6 below shows the payload of the timing advance command MAC CE.

[0114] [Table 6]

[0115]

[0116] Timing Advance Group (TAG)

[0117] A timing advance group (TAG) refers to a group of serving cells using the same timing advance value. Table 7 below shows the definition of a TAG and configuration information related to the TAG.

[0118] [Table 7]

[0119]

[0120]

[0121]

[0122] process

[0123] Uplink time alignment may be performed based on Table 8 below.

[0124] [Table 8]

[0125]

[0126]

[0127]

[0128]

[0129] The above contents (multiple TRPs and timing advance, etc.) can be applied in combination with the method proposed in the present disclosure to be described later, or can be supplemented to clarify the technical features of the method proposed in the present disclosure. The methods described below are classified only for the purpose of convenience of explanation, and some components of one method can be replaced by some components of another method, or can be applied in combination with each other.

[0130] The following describes i) a method in which a base station configures / indicates multiple TAs for a specific CC / BWP in uplink transmission of a terminal and ii) a method in which a terminal requests / acquires multiple TAs, and proposes subsequent terminal operations.

[0131] According to 3GPP standards up to NR Rel-17, the timing advance (TA) configuration of the base station for UE uplink transmission can be performed through high-layer signaling to compensate for the propagation delay between the base station and the UE. In addition, the TA for a specific cell can be configured / managed separately through the concept / definition of a timing advance group (TAG).

[0132] So far, there is no method to support multiple TA values ​​within a specific cell. However, considering the situation where the distances between different target TRPs and the UE vary greatly when M-TRP UL is sent, an enhancement will be made to set / indicate multiple (two) TA values ​​in a specific CC / BWP.

[0133] In this case, it is necessary to discuss how the base station configures / indicates multiple TA values ​​to the UE and / or how to connect multiple TA values ​​with the UE UL channel / RS. As described in Rel-18 MIMO WID Target (RP-213598) in Table 9 below, the configuration of TA values ​​for M-TRP operation based on multi-DCI (M-DCI) is considered.

[0134] [Table 9]

[0135]

[0136] Here, TA (TA value) can be based on Figure 2 and the contents described in the above timing advance (TA) related process.

[0137] In the RAN1 and RAN2 standards before Rel-18, the base station is based on N TA and N TA,offset The base station can set N as follows: TA The base station can set N based on i) RAR MAC CE or ii) TA command MAC CE. TA In addition, the base station may use the concept of a timing advance group (TAG) to configure up to 4 TAGs for a UE with respect to a specific cell or a combination of cells. The base station may configure N for each TAG. TA In other words, the N value related to the uplink timing of the UE can be determined / set based on the RAR MAC CE / TA command MAC CE for each TAG. TA value.

[0138] In Rel-18 MIMO, in order to support different TA values ​​for UEs based on the target TRP, i) the base station can set N in a specific CC / BWP. TA (or / and N TA,offset ) values ​​to configure two TRP specific values, or ii) the base station can configure a separate parameter (e.g., N TA,TRP1 and / or N TA,TRP2 ), so that except for N TA or / and N TA , offset value, a TRP-specific TA offset value is also configured / assigned. In method ii), when calculating the existing TA value of the UE, it may be necessary to additionally subtract / add the TA offset due to separate parameters. In the following, the two TA values ​​managed by methods i) or / and ii) may be represented as TA1 (or the first TA) and TA2 (or the second TA). In this case, the two TA values ​​may correspond to two TAGs. For example, TA1 corresponding to TRP1 may be associated with TAG 1, and TA2 corresponding to TRP2 may be associated with TAG 2.

[0139] As described in the WID, a scenario that supports two TA values ​​is M-DCI-based M-TRP operation. In M-DCI-based M-TRP operation, each TRP can be classified based on the CORESET pool index associated with the CORESET present in the BWP. Based on the CORESET pool index, each TRP can be classified as i) a TRP that performs DL transmission (i.e., PDCCH, PDSCH) or / and ii) a target TRP for UL transmission. For example, CORESET 0 and 1 set to CORESET pool index 0 can correspond to TRP1, while CORESET 2 and 3 set to CORESET pool index 1 can correspond to TRP 2.

[0140] In the unified TCI framework introduced in Rel-17 MIMO, the base station can use DL / UL joint TCI state and / or DL / UL individual TCI state to dynamically indicate a specific reference RS to be used as a common beam for the DL / UL receive (Rx) / transmit (Tx) beam of the UE.

[0141] The DL / UL joint TCI state may be based on the joint TCI state configured for UL and DL operations. When the unifiedTCI-StateType of the serving cell is set to "joint", the joint TCI state may be configured based on dl-OrJointTCI-StateList.

[0142] DL / UL separate TCI state can be based on DL TCI state and / or UL TCI state. When the unifiedTCI-StateType of the serving cell is set to "separate", the DL TCI state can be configured based on dl-OrJointTCI-StateList, and the UL TCI state can be configured based on ul-TCI-ToAddModList.

[0143] The TCI state (e.g., joint / DL TCI state) can be indicated / configured based on the dl-OrJoint-TCIStateList within the PDSCH-config. The dl-OrJoint-TCIStateList can i) provide a list of up to 128 TCI states (explicitlist→dl-OrJointTCI-StateToAddModList) or ii) indicate the serving cell and (DL / UL) BWP, where the list of TCI states (dl-OrJointTCI-StateToAddModList) is defined (unifiedTCI-StateRef→ServingCellAndBWP-Id). The TCI state (e.g., joint / DL TCI state) can provide a reference RS for the DM-RS of the PDSCH, the DM-RS of the PDCCH, and the quasi co-location of the CSI-RS. The TCI state (eg, joint TCI state) may provide a reference RS for determining a PUSCH based on a dynamic grant, a PUSCH based on a configured grant, and an uplink (UL) Tx spatial filter for PUCCH resources and SRS.

[0144] The UL TCI state can be indicated / configured via the ul-TCI-StateList within BWPUplinkDedicated. The ul-TCI-StateList can i) provide a list of up to 64 UL TCI states (explicitlist→ul-TCI-ToAddModList) or ii) indicate the serving cell and UL BWP, where the UL TCI state applicable to the UL BWP is defined (unifiedTCI-StateRef→ServingCellAndBWP-Id).

[0145] The Rx / Tx beam of the DL / UL channel / RS that is not a common beam target may be configured as follows: The TCI state of the unified TCI framework may be configured for each channel / RS based on RRC and MAC CE signaling.

[0146] Until Rel-17, standardization is implemented only when M / N (i.e., the number of DL / UL common beams (number of DL / UL TCI states) supported in the unified TCI framework) is M / N = 1. In other words, for M-TRP, the unified TCI framework is not supported. Specifically, in a serving cell where two CORESET pool indexes are set (for more than one value of coresetPoolIndex), unifiedTCI-StateType is not set.

[0147] Here, M / N represents the number of DL common beams (M) and / or the number of UL common beams (N). For example, M / N=1 may mean that the number of DL common beams (DL TCI state) and / or the number of UL common beams (UL TCI state) is 1. For example, M / N=1 may mean that the number of DL and UL common beams (joint TCI state) is 1.

[0148] If M / N>1 is supported in Rel-18, two or more TCI states may have a connection relationship with the source / target TRP.

[0149] Specifically, in the M-TRP operation based on M-DCI, two or more TCI states corresponding to M / N>1 may have a connection relationship with the CORESET pool index. As described above, two TA values ​​for multiple TRPs may be configured / indicated in the same manner as the existing standard through high-level signaling (e.g., MAC CE).

[0150] In the case of a UE (UE after Rel-17) supporting a unified TCI applied to FR 2, multiple TA values ​​may be connected / correspond to two or more TCI states (corresponding to M / N>1). For example, when M / N=2 or / and N=2, the first configured / indicated (first / lowest) TCI state may correspond to TA1 (e.g., TAG 1 or TA1 for TAG 1), and the second configured / indicated (second / second lowest) TCI state may correspond to TA2 (e.g., TAG 2 or TA2 for TAG 2).

[0151] Specifically, a specific payload may be included / added / defined in the MAC CE to configure / assign / activate a TA value for each of two or more TCI states corresponding to M / N> 1. For example, a payload for a target TCI state (group) for assigning each TA value (e.g., TA1 and TA2) may be present in a MAC CE message for configuring two TA values.

[0152] The agreement for multiple TA values ​​is shown in Table 10 below.

[0153] [Table 10]

[0154]

[0155]

[0156]

[0157]

[0158] The operations / methods / terms according to the embodiments of the present disclosure described below may be based on Table 10. For example, the operations / methods / terms according to the embodiments of the present disclosure described below may be interpreted / changed / applied based on Table 10.

[0159] For example, multiple TA values ​​may mean multiple timing advance groups (TAGs) or multiple TAG IDs. One TA value may mean one TAG (TAG ID).

[0160] For example, multiple TA values ​​may mean TA values ​​corresponding to multiple TAGs (multiple TAG IDs). One TA value may mean a TA value corresponding to one TAG (TAG ID) (in Table 1, T TA ).

[0161] In a TCI state configuration (TCI state pool) for a unified TCI, two TRP-specific TA values ​​(e.g., two TAGs or TAs corresponding to two TAGs) may be connected / correspond to a specific TCI state (group). When two TA values ​​are connected / correspond to two TCI states (corresponding to M / N>1), the UE may perform UL transmission using the TRP-specific TA value connected to each TCI state in UL transmission using each TCI state. For example, the timing of UL transmission based on a first TCI state may be determined based on a TA associated with the first TCI state (e.g., a first TAG or a first TA for the first TAG), and the timing of UL transmission based on a second TCI state may be determined based on a TA associated with the second TCI state (e.g., a second TAG or a second TA for the second TAG).

[0162] However, even if the UE supports unified TCI, the reference RS of UL spatialRelationInfo or / and UL TCI cannot be applied to FR 1 (frequency range 1). For example, the UE capability for spatialRelation of the UE may be defined as shown in Table 11 below.

[0163] [Table 11]

[0164]

[0165] Referring to Table 11, for FR1 (eg, UE operation in FR1), the spatial relationship for PUCCH and SRS is not supported.

[0166] Therefore, for FR1, when the base station uses the unified TCI framework to configure / indicate two TA values, there may be ambiguity in UE operation.

[0167] The present disclosure describes i) a method for a BS to configure / indicate multiple TAs for a specific CC / BWP for uplink transmission (especially FR1) of a UE (as described above), and ii) a method for a UE to request / acquire multiple TAs, and proposes subsequent UE operations.

[0168] In the present disclosure, “ / ” may be interpreted as “and”, “or” or “and / or” according to the context.

[0169] Proposal 1

[0170] The UE may receive a unified TCI configuration corresponding to M / N>1 (in FR1 operation). For example, the UE may receive configuration information for two or more unified TCI states from a base station (BS). The two or more unified TCI states may include at least one of the following: i) two or more joint TCI states, ii) two or more DL TCI states, and / or iii) two or more UL TCI states.

[0171] When the base station configures two CORESET pool indexes within the CC / BWP for the UE to perform M-TRP operation based on M-DCI, the UL-related TCI state (e.g., DL / UL joint TCI state and / or DL / UL separate TCI state) connected / corresponding to each of the two CORESET pool indexes may be configured / indicated. For example, the UE may receive configuration information for multiple CORESETs from the base station. A CORESET based on two CORESET pool indexes may be configured based on the configuration information. The UE may receive information indicating two UL-related TCI states (e.g., two joint TCI states or two UL TCI states) connected / corresponding / related to the two CORESET pool indexes from the base station. The information indicating the two UL-related TCI states may be received based on at least one of a DCI, a MAC CE, or an RRC message.

[0172] The two TRP-specific TA values ​​may be connected to / correspond to two UL-related TCI states. In addition, configuring a power control parameter set to each of the two UL-related TCI states may be used as a power control parameter set for each target TRP in an M-TRP UL transmission (e.g., M-TRP PUSCH / PUCCH repetition) (for S-DCI-based M-TRP operation).

[0173] Specifically, since UL spatialRelationInfo (UL TCI) information is not applicable to FR1, the TCI status for configuring / indicating two TA / PC parameter sets may be configured / used as follows.

[0174] The reference RS corresponding to QCL Type-D or / and UL spatialRelationInfo (UL TCI) may not be configured for these two TCI states. For example, in each TCI state, the referenceSignal field (in QCL-Info) may not exist. For example, the UE may not expect to configure the referenceSignal field (in QCL-Info) in each TCI state.

[0175] If the reference RS corresponding to QCL type-D or / and UL spatialRelationInfo (UL TCI) is configured to two TCI states, the UE can skip / ignore / override the reference RS and perform UL transmission only using the TA / PC information corresponding to each target TRP (e.g., first TCI / second TCI or CORESET pool index 0 / 1).

[0176] As described above, the UE may determine TA / PC information corresponding to each target TRP (e.g., each TRP among two target TRPs) based on two TCI states. The UE may perform UL transmission for each target TRP based on TA information / PC information. The UL transmission timing (e.g., uplink frame) for each target TRP may be determined based on TA information (e.g., TAG or TA value for TAG). The UL transmission power for each target TRP may be determined based on PC information (e.g., one or more PC parameters).

[0177] The TCI state may be configured / indicated through RRC, MAC CE or / and DCI in the same manner as the existing Rel-17 operation. If the TCI state is indicated through DCI, the base station may use i) DL( / UL) grant DCI or ii) DL( / UL) grant DCI without data scheduling. The base station may dynamically indicate the TCI state for each target TRP through the TCI field of the DCI. For example, if the above-mentioned TCI indication through DCI is performed in a CORESET with a specific CORESET pool index, the UE may use the corresponding TCI to receive / send a DL / UL channel / RS connected / corresponding to the CORESET pool index.

[0178] In this case, according to the Rel-17 standard, in the TCI indication of the granted DCI scheduled with no data, the UE can send an Ack( / Nack) after receiving the DCI (via PUCCH and / or PUSCH) (for example, using an ACK / NACK mechanism similar to the ACK / NACK mechanism for SPSPD SCH release, utilizing both type 1 and type 2 HARQ-ACK codebooks).

[0179] If the above operation is performed in FR1 (ie, indicated by TCI of the grant DCI with no data scheduling), the UE may skip Ack ( / Nack) transmission. Skipping Ack ( / Nack) transmission considers the following technical issues.

[0180] In Rel-17, the base station checks whether the UE has received the TCI state including the beam information (e.g., reference RS) for the reception / transmission of the UE indicated by the DCI well. Thereafter, the base station can use the Tx / Rx beam of the base station corresponding to the indicated TCI information in subsequent DL / UL transmission / reception. On the other hand, the TCI state indication for not including the Tx / Rx beam information of the UE allows the base station to configure / indicate two TAs (e.g., two TAGs or two TAs corresponding to two TAGs) and two PCs (e.g., two parameter sets). Whether the indication for TA / PC has been successfully sent can be determined by the subsequent transmission of the UE. Specifically, after the base station receives the subsequent UL transmission of the UE, the base station can determine whether the TA / PC indication made by the previous DCI has been successfully sent to the UE, and whether the UE has performed UL transmission based on the indication.

[0181] Therefore, the UE can skip the Ack ( / Nack) transmission for the indication of the TCI state (the indication of the TCI state that does not include the Tx / Rx beam information of the UE) in FR1.

[0182] In addition, since Rx / Tx beam indication is performed dynamically in the existing Rel-17 unified TCI framework, concepts such as beam application time (BAT) have been defined to determine at which time the UE should perform the change of the corresponding Rx / Tx beam from the time the DCI is received. For example, the beamAppTime parameter can be set based on the PDSCH-config. The beamAppTime parameter indicates the first time slot to which the unified TCI indicated by the DCI is applied. The beamAppTime parameter can indicate the number of symbols (Y) (e.g., n1, n2, n4, n7, n14, n28, n42, n56, n70, n84, n98, n112, n224, n336). The first time slot can be a time slot of at least Y symbols after the last symbol of the acknowledgment (Ack) of the joint or individual DL / UL beam indication.

[0183] As described above, when a unified TCI framework is used to configure / indicate TA / PC, BAT can be used as a setting value for the time when ULTA / PC should be applied. Alternatively / and, since the TCI state is independent of the beam application, the UE may not expect to configure BAT, or may expect the BAT value to be set to 0. As a specific example, it can be assumed that the unified TCI state for FR1 is indicated by DCI (e.g., DL authorization DCI, UL authorization DCI, DCI without DL authorization, or DCI without UL authorization). Since the indicated unified TCI state is independent of the beam application, the transmission of HARQ-ACK information for DCI can be skipped. Since the transmission of HARQ-ACK information is skipped, the application time (e.g., symbol, time slot, subframe, or frame) for the indicated unified TCI state cannot be determined by the beamAppTime parameter. In this case, the UE may not use the beamAppTime parameter even if the beamAppTime parameter is configured. In other words, the UE can ignore the beamAppTime parameter. For example, the time (e.g., symbol, slot, subframe, or frame) for applying the indicated unified TCI state may be determined without applying the beamAppTime parameter. For example, the time for applying the indicated unified TCI state may be determined regardless of the beamAppTime parameter.

[0184] Proposal 2

[0185] For two TRP-specific TA values ​​or / and two TRP-specific PC parameter sets, the base station can configure separate parameters. Specifically, (in FR1 operation) two TRP-specific TA values ​​or / and two TRP-specific PC parameter sets can be configured as / connected to / correspond to separately configured parameters.

[0186] A separate parameter may include a TRP specific TA value. In this case, the parameter may be configured as i) or ii) below.

[0187] i) A single parameter including both the first TA value and the second TA value may be configured.

[0188] ii) Two parameters may be configured. The first parameter may include a first TA value, and the second parameter may include a second TA value.

[0189] Individual parameters may include a TRP-specific PC parameter set. In this case, the parameters may be configured as follows i) or ii) below.

[0190] i) A single parameter including a first PC parameter set and a second PC parameter set may be configured.

[0191] ii) Two parameters may be configured. The first parameter may include a first PC parameter set, and the second parameter may include a second PC parameter set.

[0192] In i), a specific CORESET pool index may be connected to / correspond to a specific TA value or / and a specific PC parameter set within a single parameter. For example, CORESET pool index 0 may be connected to a first TA value / first PC parameter set, and CORESET pool index 1 may be connected to a second TA value / second PC parameter set.

[0193] In ii), a specific CORESET pool index may be connected to / correspond to a specific parameter among the two parameters. For example, CORESET pool index 0 may be connected to the first parameter, and CORESET pool index 1 may be connected to the second parameter.

[0194] As described above, the first TA value / first PC parameter set and the second TA value / second PC parameter set may be configured as specific parameters and may be connected to a specific CORESET pool index. When performing UL transmission associated with / corresponding to a specific CORESET pool index, the UE may perform UL transmission by utilizing a TRP-specific TA value or / and a TRP-specific PC parameter set connected to the corresponding CORESET pool index.

[0195] For more flexible configuration, the TRP-specific TA value or / and two TRP-specific PC parameter sets corresponding to the above two TA values ​​may be configured / connected / mapped / updated in each CORESET (group) configuration. Therefore, when transmitting UL related to a specific CORESET (group), the UE may perform UL transmission by utilizing the TRP-specific TA value or / and TRP-specific PC parameter set configured to the corresponding CORESET.

[0196] In the above embodiment, the expression “(a specific parameter and another parameter) may be connected / correspond” may mean that the specific parameter and another parameter may be associated through RRC / MAC CE / DCI signaling.

[0197] Unless the implementations of Proposal 1 and Proposal 2 are mutually exclusive, the implementations of Proposal 1 and the implementations of Proposal 2 can be combined and applied to UE / BS operations. For example, the operation of configuring a unified TCI (Proposal 1) and the operation of configuring separate parameters (Proposal 2) cannot be combined, but other implementations can be combined and applied. Specifically, the implementation of Proposal 1 related to two TRP-specific TA values ​​(two TRP-specific PC parameter sets) and the implementation of Proposal 2 can be combined and applied to UE / BS operations.

[0198] Multi-TA acquisition

[0199] In order to configure the above-mentioned multiple TA values, it is necessary to determine how the BS will request / acquire multiple TA values. Hereinafter, a method and terminal operation for BS / UE to obtain multiple TA values ​​are proposed. Specifically, the following proposal 3 proposes a method for UE to perform two TA acquisitions and a method for configuring TA in the BS without RACH enhancement, and proposal 4 proposes a method for UE to perform two TA acquisitions and a method for configuring TA in the BS through RACH enhancement.

[0200] Hereinafter, the first TA or the second TA connected to / corresponding to a specific CORESET pool index may mean that the first TA or / and the second TA are connected to / corresponding to a first TCI state or / and a second TCI state (for common beam operation in a unified TCI framework).

[0201] Hereinafter, the first TA and the second TA may refer to the first TA value / second TA value managed for configuring two TRP specific TA values ​​within a specific TAG (i.e., one TAG). Alternatively, the first TA and the second TA may refer to the first TA value and the second TA value managed corresponding to different TAGs (first TAG and second TAG) for the same CC (set).

[0202] Proposal 3

[0203] A method for performing two TA acquisitions and a method for configuring a TA in a BS without RACH enhancement will be described below.

[0204] Proposal 3-1

[0205] The UE may perform RACH transmission using a single (and / or primary / first) TA during RACH transmission including initial access (e.g., RACH commanded by PDCCH, RACH transmitted when a TA timer expires, etc.). The BS may measure the first TA / second TA by receiving subsequent SRS of the UE. That is, a method for configuring / indicating an implicit / explicit connection / correspondence relationship between a specific SRS resource (set) and a specific CORESET pool index is proposed.

[0206] The following operations may be performed on the aperiodic SRS resource (set) corresponding to dynamic scheduling. The UE may receive an SRS trigger DCI in a CORESET with a specific CORESET pool index. At this time, the aperiodic SRS resource (set) sent by the UE may be connected to / correspond to the specific CORESET pool index.

[0207] Regarding the periodic / semi-persistent SRS resource(s) sent by the UE via RRC / MAC CE signaling, the following operations may be performed. The BS may (explicitly) configure / connect / correspond to the associated CORESET pool index for a specific SRS resource(s). In this way, the UE / BS may know which CORESET pool index a specific SRS resource(s) is connected to / corresponds to.

[0208] As a result, the BS / UE can understand that the specific P / SP / AP SRS resource (set) sent by the UE is associated / corresponds to a specific CORESET pool index. In other words, the BS can identify the CORESET pool index associated / corresponds to the specific P / SP / AP SRS resource (set) sent by the UE. The BS can measure the first TA or / and the second TA through the SRS sent by the UE.

[0209] According to an embodiment, the first ( / primary) TA may be acquired through an existing RACH procedure. The second TA may be acquired through an SRS associated with CORESET pool index 1 as described above.

[0210] Proposal 3-2

[0211] The BS may measure the first TA or / and the second TA connected / corresponding to a specific CORESET pool index through Proposal 3-1. The BS may configure / indicate a TRP specific TA value (ie, the first TA / the second TA) by utilizing an enhanced RAR MAC CE format or / and an enhanced TA command MAC CE.

[0212] As an example, the BS may configure the target CORESET pool index in the enhanced MAC CE format. Through this, the TA value associated with the corresponding CORESET pool index may be configured / indicated. As a specific example, the enhanced MAC CE format may include a field indicating the target CORESET pool index.

[0213] As an example, the BS may configure the first TCI / second TCI corresponding to M / N>1 in the enhanced MAC CE format for TRP-specific common beam operation as a target. In this way, the TA value associated with / corresponding to the first TCI / second TCI may be configured / indicated. As a specific example, the enhanced MAC CE format may include a field indicating a target TCI (e.g., a first TCI state or a second TCI state).

[0214] As an example, the BS may configure a specific joint and / or individual UL TCI state index in the enhanced MAC CE format as the target. In this way, the TA value to be applied to the corresponding TCI state may be configured / indicated. Specifically, the TA value used to configure / indicate the second TA value in the MAC CE format may be configured / specified / indicated to have a TA granularity or / and value range different from the TA granularity or / and value range of the first TA value in the same MAC CE format. This is because in M-TRP operation, the difference in UL TA values ​​for different TRPs may differ from the DL timing reference by the CP length or more. The granularity of the second TA value (when the same number of bits as the first TA value is used) may be represented by a step size slightly larger than that of the first TA value. The value range of the second TA value (when the same number of bits as the first TA value is used) may be represented by a value range slightly larger than that of the first TA value.

[0215] As described above, the BS can configure / indicate the first TA / second TA for a specific target CORESET pool index / target common TCI / target TCI state. In the transmission of the UL channel / RS (especially the SRS in Proposal 3-1) associated with the target CORESET pool index / target common TCI / target TCI state, the BS can perform uplink transmission by applying the configured / indicated first TA value / second TA value.

[0216] The BS can perform update / activation of the TRP-specific TA value by measuring the UE's TRP-specific SRS transmission based on Proposal 3-1 after configuring / indicating the TRP-specific TA through Proposal 3-2.

[0217] Proposal 4

[0218] Hereinafter, a method for performing two TA acquisitions and a method for configuring a TA in a BS without RACH enhancement will be described.

[0219] Proposal 4-1

[0220] A method may be considered to support TRP-specific RACH transmissions for TRP-specific TA measurements.

[0221] The BS may perform grouping on the SSBs (SS / PBCH blocks) used by the UE for RACH transmission. The BS may associate / correspond a specific SSB group with a specific CORESET pool index. For example, the SSBs corresponding to SSB indexes 0 to 31 may be connected to / correspond to CORESET pool index 0, and the SSBs corresponding to SSB indexes 32 to 64 may be connected to / correspond to CORESET pool index 1. Here, the SSB index may be the SS / PBCH index of the SS / PBCH block.

[0222] Based on the grouping, when configuring / instructing to send RACH (of PDCCH command) to the UE, the BS can configure / instruct to use a specific SSB index. RACH may mean a random access preamble. For example, the BS may send a DCI (e.g., DCI format 1_0) containing information related to the PDCCH command to the UE. The random access procedure is initiated by the PDCCH command. The UE sends a random access preamble to the BS. The information related to the PDCCH command may include an SS / PBCH index. The SS / PBCH index may be connected to / associated with a specific CORESET pool index. The random access preamble may be sent based on the SS / PBCH index.

[0223] By enabling the UE to send a RACH corresponding to an SSB (based on a specific SSB index), the BS can measure a TRP-specific TA associated / corresponding to each CORESET pool index by utilizing the RACH.

[0224] According to an embodiment, multiple RACH transmissions can be indicated / scheduled to the UE via a single PDCCH (e.g., a single DCI) so that when the BS indicates a RACH transmission (of a PDCCH instruction), the UE can send a RACH associated with each CORESET pool index. As a specific example, a single DCI may include information related to the PDCCH instruction. At this time, the information related to the PDCCH instruction may include two SS / PBCH indexes. The UE can send two random access preambles to the BS based on these two SS / PBCH indexes. With this mode, a single PDCCH transmission can be utilized to reduce overhead / delay, and the UE can be instructed to send all RACHs destined for each TRP. The BS can perform TA measurements for each TRP at a time.

[0225] According to an embodiment, the connection / correspondence between a specific SSB group and a specific CORESET pool index can be configured / defined / specified by connecting / corresponding a specific CORESET pool index and a PRACH preamble index / RACH timing / PRACH mask index. Specifically, the DCI associated with the PDCCH instruction (e.g., DCI format 1_0) may include a random access preamble index, an SS / PBCH index, and a PRACH mask index. When the value of the random access preamble index is not zero, the PRACH mask index indicates the RACH timing associated with the SS / PBCH indicated by the SS / PBCH index. The specific CORESET pool index may be configured to be connected / corresponded to at least one of a PRACH preamble index, a PRACH mask index, or a RACH timing.

[0226] In addition, if a connection / correspondence relationship between a specific SSB group and a specific CORESET pool index is defined / configured, the following operations may be performed. The BS may schedule the UE's RACH transmission according to the PDCCH instruction through the CORESET with the specific CORSET pool index. At this time, the UE may perform RACH transmission corresponding to the SSB connected / corresponding to the specific CORESET pool index (or such RACH transmission may be forced) (even if there is no SSB index indication in the corresponding PDCCH). In other words, the UE may perform RACH transmission based on the CORESET pool index of the CORESET in which the DCI (related to the PDCCH instruction) is received.

[0227] The RACH transmission in the above-mentioned proposal 4-1 cannot be used for RACH transmission at the time of initial access.

[0228] Even if the UE performs TRP-specific RACH transmission as described above, since the UE performs all operations based on a specific SSB in the RA process, the TA value does not change during UL transmission in the RA process. That is, the UE performs UL transmission by using the same TA value. The RA process may include a 4-step RACH process and / or a 2-step RACH process. For example, a 4-step RACH process (e.g., contention-based RACH) may include operations of sending message 1 (preamble), receiving message 2 (RAR), sending message 3 (PUSCH), and receiving message 4 (contention resolution). For example, a 2-step RACH process may include operations of sending message A (preamble and PUSCH) and receiving message B (RAR).

[0229] Proposal 4-2

[0230] Hereinafter, a method for managing a TRP-specific TA timer will be described.

[0231] According to the existing TA maintenance operation, when the timer corresponding to the primary timing advance group (PTAG) expires due to timeAlignmentTimer (per TAG), the UE can release UL transmission and send RACH. This embodiment proposes a method for managing timeAlignmentTimer corresponding to the TA timer to be TRP-specific.

[0232] The UE may manage up to two TA timers or / and a first TA value and a second TA value within a single TAG corresponding to CORESET pool indexes 0 and 1. Here, the two corresponding timers may be timers configured to different TAGs for different TRPs.

[0233] According to the existing operation, when the TA timer expires, the UE sends a RACH corresponding to a random SSB (e.g., an SSB based on one of the SSB indexes). On the other hand, according to this embodiment, when the TA timer associated with / corresponding to a specific CORESET pool index or / and a specific first TA value / second TA value expires, the UE may send a RACH based on the CORESET pool index associated with / corresponding to the expired TA timer. That is, a RACH corresponding to an SSB connected to / corresponding to the corresponding CORESET pool index may be sent.

[0234] By such operation, when the TA value corresponding to the TRP expires, the UE can send a RACH for a specific TRP. The BS can measure the TA value of the UE from the corresponding TRP and configure / indicate / update the TRP-specific TA value to the UE (as in Proposal 3-2).

[0235] In addition, it can be assumed that in the existing operation, when the timer corresponding to the PTAG expires, a UL out-of-sync (OOS) operation is performed, but in the case of managing two TRP-specific timers corresponding to the first TA and the second TA, respectively, as in the above-mentioned Proposal 4-2, one timer expires and the other timer does not expire. In this case, the UE may not need to perform all predefined UL OOS operations (for example, not performing an RRC release operation, etc.). If both timers expire, all predefined UL OOS operations may need to be performed.

[0236] Proposal 4-3

[0237] Hereinafter, a method for sending a RAR corresponding to a TRP-specific RACH transmission by a BS will be described.

[0238] According to the above proposals 4-1 or / and 4-2, the specific RACH transmission of the UE corresponds to a specific SSB. According to the correspondence between the SSB index and the CORESET pool index, the specific RACH transmission and the specific CORESET pool index may naturally also have a correspondence. A method for sending a TRP-specific RAR by the BS for a TRP-specific RACH transmission of the UE is proposed.

[0239] The BS may receive a specific RACH having a corresponding relationship with a specific CORESET pool index. The BS may send a RAR for the corresponding RACH to the UE based on some CORESETs among the CORESETs having the specific CORESET pool index. For example, some CORESETs may be CORESETs with the lowest index among the CORESETs configured with the corresponding CORESET pool index.

[0240] In the existing standard operation, the UE may receive a configuration for a type 1-PDCCH common search space (CSS) set for receiving RAR from the BS. Specifically, the type 1-PDCCH CSS set may be configured based on the ra-searchspace of the PDCCH-ConfigCommon IE. For example, the RAR may be received based on the PDCCH candidates in the monitoring search space set (SS set).

[0241] Proposal 4-3 proposes a method that enables a UE to receive a TRP-specific RAR through a separate UE-specific search space (USS) set in addition to a Type 1-PDCCH CSS set.

[0242] According to an embodiment, a method for connecting / configuring a CORESET for receiving a separate USS set and a TRP-specific RAR may be considered. Each USS set may be connected / correspond to a CORESET having a different CORESET pool index.

[0243] According to an embodiment, the BS may send a RAR for a RACH used for first / primary (and / or corresponding to CORESET pool index 0) TA value measurement through an existing type 1-PDCCH CSS set. According to an embodiment, the BS may send a RAR for a RACH used for first / primary (and / or corresponding to CORESET pool index 1) TA value measurement through an existing type 1-PDCCH CSS set. When a USS set is used for TRP-specific RAR reception as described above, a separate RNTI for TRP-specific RAR reception may be configured in the UE.

[0244] According to an embodiment, the UE may receive a TRP-specific RAR based on the configuration of multiple CSS sets (e.g., considering the configuration of two CSS sets of two TRPs). Each USS set may be connected to / correspond to a CORESET with a different CORESET pool index.

[0245] When separate multiple CSS sets are configured for TRP-specific RAR reception, the first ra-searchspace corresponding to the first TRP / CORESET pool index 0 and the second ra-searchspace corresponding to the second TRP / CORESET pool index 1 can be configured based on the PDCCH-ConfigCommon IE.

[0246] Based on the CORESET configuration connected to / corresponding to the search space that does not exist in the first ra-searchspace configuration, the UE may assume the following configuration (as a default operation). Specifically, CORESET 0 within the CC / BWP (or the CORESET with the lowest ID among the CORESETs corresponding to CORESET pool index 0) may be connected to the first ra-searchspace configuration.

[0247] Based on the absence of a CORESET configuration connected / corresponding to the search space in the second ra-searchspace configuration, the UE may assume the following configuration (as a default operation). Specifically, the CORESET with the lowest ID among the CORESETs corresponding to CORESET pool index 1 within the CC / BWP may be connected to the second ra-searchspace configuration.

[0248] The MAC CE format sent by such a TRP-specific RAR may include all configurations / indications for multiple TA values ​​within a specific CC / BWP, as in Proposal 3-2 above. Alternatively, the MAC CE format sent by a TRP-specific RAR may only include configurations / indications for TA values ​​associated / corresponding to the CORESET pool index through which the RAR is sent.

[0249] For a TA value associated / corresponding to a specific CORESET pool index indicated by a MAC CE format, the UE may specify / define a DL timing reference based on receiving an RAR (UL grant DCI) sent in a CORESET with the corresponding CORESET pool index. The UE may apply the TA value indicated from the corresponding DL timing reference. In the case of M-DCI-based M-TRP in a non-ideal backhaul scenario (e.g., a scenario where there is no coordination between TRPs), the DL timing references between TRPs may be significantly different. In this case, the BS may indicate to the UE an appropriate TRP-specific TA value for each DL timing reference used for each TRP through the above operations.

[0250] Proposal 5

[0251] Proposal 5 describes additional implementations related to Proposal 4. Specifically, the following will study i) the implementation related to the timers related to the two TAs of Proposal 4-2, and ii) the implementation related to the RAR corresponding to the TRP-specific RACH transmission of Proposal 4-1 and the corresponding RACH transmission of Proposal 4-3.

[0252] Proposal 5-1

[0253] Hereinafter, a method for managing timers associated with two TAs will be described.

[0254] In the above-mentioned Proposal 4-2, a method for managing a TA for each TRP (TRP-specific TA) in a UE-specific CC / BWP in an M-TRP environment based on M-DCI is proposed. Specifically, according to Proposal 2, timers associated with each TA are managed separately. A method different from the operation of the above-mentioned Proposal 4-2 can be considered.

[0255] Specifically, according to Proposal 5-1, when the timer of a specific TA value (eg, the first TA value) among two TA values ​​expires, the above-mentioned UL OOS operation may be performed. In addition, the embodiments may assume / consider at least one of the following technical matters.

[0256] 1) Among multiple TRPs, there may be a master TRP (e.g., a CORESET pool with CORESET pool index 0) that transmits system information. For example, a specific TA value may be associated with the master TRP (CORESET pool index 0).

[0257] 2) The second TA value of the second TRP (ie, the CORESET pool with a CORESET pool index of 1) may be managed by an offset value from the first TA value of the first TRP (ie, the CORESET pool with a CORESET pool index of 0).

[0258] Only one timer related to TA may be configured in the UE. For example, a timer (ie, timeAlignmentTimer) may be configured only for the first TA value. In this case, UL OOS operation may be performed based on the expiration of the configured timer.

[0259] A timer associated with each TA may be configured in the UE. That is, a timer associated with multiple TAs may be configured in the UE. For example, timers (i.e., a first timeAlignmentTimer and a second timeAlignmentTimer) may be configured for a first TA value and a second TA value, respectively. In this case, a UL OOS operation may be performed based on the expiration of a configured specific timer (a first timeAlignmentTimer or a second timeAlignmentTimer). The UL OOS operation may be based on an operation performed when a timer associated with a PTAG (or STAG) expires. For example, the UL OOS operation may include the operation performed when the timeAlignmentTimer expires in Table 8.

[0260] When the timer for a specific TA value (e.g., the first TA value) expires, the UE may perform a release operation for all UL channels / RSs (of CC / BWP associated with the corresponding TA value (or associated with the corresponding TAG)). More specifically, the UE may perform a release operation and a clear operation based on Table 8. Based on the expiration of the above timer, the UE may i) release the PUCCH and SRS, and ii) clear the configured downlink assignments, configured uplink grants, and PUSCH resources (e.g., PUSCH resources for semi-persistent CSI reporting). In addition, the UE may perform RACH transmission to update the expired TA value.

[0261] This proposal can be applied to the case where the first TA and the second TA are managed in one TAG, and can also be applied to the case where the first TA and the second TA are managed in two different TAGs.

[0262] As an example, timers may be set on both the first TA and the second TA, and when at least one of the timers expires, a UL OOS operation may be performed. As an example, a UL OOS operation may be performed when a timer of a TA value related to a PTAG expires. For example, in a specific CC / BWP, the first TA value may correspond to a PTAG, and the second TA value may correspond to a STAG, so in this case, a UL OOS operation may be performed when a timer corresponding to the first TA value expires.

[0263] Embodiments related to the operation of the UE when timers associated with two TAs expire will be described below.

[0264] Specifically, in the UE-specific CC / BWP (in the M-TRP environment based on M-DCI), it can be assumed that two TAs for two TRPs are managed based on two TAGs. Hereinafter, an implementation method related to the operation when the time associated with a specific TA value (and / or a specific TAG) expires will be described in detail.

[0265] Table 8 shows the contents of the method for managing TA through TimeAlignmentTimer (TAT) in TAG. In addition, according to the current standardization discussion, two TAGs can be configured to manage two TA values ​​for a specific serving cell ( / BWP). In other words, two TAGs belonging to one serving cell can be configured. The agreement according to the standardization discussion is shown in Table 12 below.

[0266] [Table 12]

[0267]

[0268] In this case, a time alignment timer (TAT) may be configured for each of the two TAGs. The TA value within each TAG may be managed by the TAT configured for each TAG.

[0269] At this time, if only one of the TATs of each TAG expires, there may be ambiguity as to which of the following operations 1) and 2) the UE should perform.

[0270] 1) The UE may continue to perform UL / channel / RS transmission associated with the expired TAG (TA value within the expired TAG).

[0271] 2) The UE may stop transmission of UL channels / RS and release UL transmission similar to UL OOS operation.

[0272] Here, the UL channel / RS may be associated with a CORESET pool (eg, CORESET pool index 0 or 1) or / and a TRP associated with / corresponding to an expired TAG (TA value within the expired TAG).

[0273] The following specifically describes implementation methods related to solutions to the above-mentioned problems in Proposals 5-1a to 5-1c.

[0274] Proposal 5-1a

[0275] The UE may perform transmission of a UL channel / RS associated with a TAG with TAT expiration. As described above, the UL channel / RS may be associated with a CORESET pool or / and a TRP associated with / corresponding to a TAG with TAT expiration.

[0276] As an example, the base station may configure / schedule a UL channel / RS related to the corresponding CORESET pool or / and TRP (even if the TAT expires). The UE may perform UL transmission for the configured / scheduled UL channel / RS based on the expired TA.

[0277] As an example, after the UE's UL transmission, the following operations may be performed. The base station may adjust the UL transmission through (absolute and / or relative) TAC MAC CE. Specifically, the base station receiving the UL channel / signal from the UE based on the expired TAT may send a TAC MAC CE to the UE.

[0278] It may be assumed that the UL synchronization (or UL timing synchronization) is distorted / changed to such an extent that the UL transmission cannot be adjusted by the TAC MAC CE.

[0279] As an example, after the UE's UL transmission, the following operations may be performed: The base station may trigger a RACH (related to the corresponding TAG / CORESET pool index / TRP) via a PDCCH command.

[0280] As an example, the base station may not perform subsequent configuration / scheduling for the UL channel / RS related to the CORESET pool index / TRP (if the base station determines that the UE's UL synchronization is destroyed).

[0281] As an example, the base station can perform UL channel / RS configuration / scheduling by utilizing a CORESET indexed by another CORESET pool. In other words, based on the expiration of the first TAT among the first TAT and the second TAT, the base station can perform UL channel / RS configuration / scheduling based on the CORESET indexed by the CORESET pool associated with the second TAT.

[0282] As an example, the UE may discard the UL channel / RS associated with the expired TAT. Specifically, the base station may configure / schedule the UL channel / RS associated with the expired TAT to the UE. Since the TAT associated with the configured / scheduled UL channel / RS expires, the UE may override / ignore the configuration / scheduling of the corresponding UL channel / RS. The corresponding UE may discard the transmission of the configured / scheduled UL channel / RS.

[0283] Proposal 5-1b

[0284] The UE may report information related to the TAG ID of the TAT expiration in the two TAGs to the base station. For example, the UE may send information for the corresponding TAG ID to the base station. For example, the UE may send information for the CORESET pool index or / and TRP index related / corresponding to the corresponding TAG ID to the base station.

[0285] The UE may report i) the TAT of a TAG associated with a specific TAG-ID or ii) the TAT expiration of a TAG associated with a specific CORESET pool index or / and TRP to another CORESET pool or / and TRP associated with a TAG whose TAT has not expired. As an example, the UE may send information related to an expired TAT (e.g., a TAG-ID and / or a CORESET pool index) to a base station based on a CORESET pool index associated with a TAG whose TAT has not expired (or for a TRP associated with a TAG whose TAT has not expired).

[0286] As an example, the above UE operation is an operation triggered by an event based on TAT expiration of a specific TAG, and information related to the expired TAT can be reported through a scheduling request based on a preconfigured PUCCH resource. Hereinafter, the above UE operation will be described in detail.

[0287] The base station may configure / indicate to the UE a scheduling request (SR) resource associated with a specific TAG (i.e., a PUCCH resource associated with the SR). For example, a scheduling request resource (PUCCH resource) associated with a specific TAG may mean an SR resource (SR-PUCCH resource) configured with a transmit beam / power control associated with another CORESET pool index other than the CORESET pool index associated with the TAG.

[0288] The UE may send an SR based on the SR-PUCCH resource associated / corresponding to the TAG based on the TAT expiration of the specific TAG. As described above, the TAT expiration of the specific TAG may be reported to the base station through the SR sent based on the PUCCH resource related to the specific TAG.

[0289] A base station that receives a report of TAT expiration for a specific TAG may perform the following operations. The base station may or may not perform scheduling of UL channels / RS for the CORESET pool associated / corresponding to the TAG. When performing scheduling of UL channels / RS, the base station / UE may perform the operations of the above-mentioned proposal 5-1a after reporting TAT expiration for a specific TAG.

[0290] According to an implementation, the expiration of the TAT of a specific TAG can be reported via RACH transmission. When the TAT of a specific TAG among two TAGs within a CC / BWP expires, the UE can perform UE-triggered RACH transmission (as in the implementation of the above-mentioned proposal 4-1) by utilizing RACH-related resources related to the TAG ID (or / and CORESET pool index / TRP index) with TAT expiration. In this case, the base station can not only identify the expiration of the TAT of a specific TAG, but also obtain the TA value of the corresponding TAG based on the RACH transmission of the UE. The base station can indicate the updated TA value to the UE via RAR MAC CE and / or (absolute and / or relative) TAC MAC CE.

[0291] In Proposal 5-1a and Proposal 5-1b, when the TAT of a specific TAG among two TAGs within the UE CC / BWP expires, the UE shall be able to perform UL OOS operations (operations defined in Table 13 below). Specifically, the UE shall be able to perform OOS operations on UL channels / RSs associated / corresponding to the CORESET pool index and / or the TRP index associated with the TAG ID (when the TAT corresponds to / is connected to the PTAG or corresponds to / is connected to the STAG).

[0292] However, in the UE CC / BWP in the M-TRP environment based on M-DCI, DL reception / UL transmission is performed based on two CORESET pool indexes / TRP indexes. Therefore, even if the TAT of a specific TAG related to / corresponding to a single CORESET pool index expires, the UL OOS operation in Table 13 below may not be performed.

[0293] [Table 13]

[0294]

[0295] In the following proposal 5-1c, an implementation method related to the (CORESET pool / TRP level) UL OOS operation performed based on the configuration of two TAGs within the CC / BWP is described. Specifically, (1) the case where the two TAGs are composed of PTAGs, (2) the case where the two TAGs are composed of PTAGs and STAGs, and (3) the case where the two TAGs are composed of STAGs are described in order.

[0296] Proposal 5-1c

[0297] Hereinafter, the UE operation when the TAT corresponding to / connected to a specific (single) TAG within the UE CC / BWP expires is described in detail.

[0298] Proposal 5-1c_(1)

[0299] When the two tags in the UE CC / BWP are a combination of PTAG+PTAG

[0300] When the two TAGs are a combination of PTAG+PTAG, the corresponding cell may be PCell and / or PSCell (SpCel). When both TATs associated with the two TAGs of the corresponding cell expire, the UE may perform all UL OOS operations in Table 13 that should be performed based on the expiration of the TAT of the PTAG.

[0301] When the TAT associated with one of the two TAGs expires, the UL OOS operations that should be performed based on the expiration of the TAT of the PTAG in Table 13 except for "Maintain the N of this TAG" may not be performed. TA(defined in TS 38.211 [8])" operation. As an example, in Table 13, the operation performed based on the expiration of the TAT of the PTAG may be performed based on the expiration of both TATs, and when only one TAT expires, the UE may not perform the corresponding UL OOS operation. As an example, in Table 13, the operation performed based on the expiration of the TAT of the PTAG may be performed based on the expiration of both TATs, and when only one TAT expires, the UE may perform the corresponding UL OOS operation at the TRP level (e.g., CORESET pool index or TAG).

[0302] The above embodiment takes into account the following technical matters. Since only one of the two TAGs (corresponding to PTAG) within the CC / BWP expires, the UL transmission of the CC / BWP can be performed by using the TA value of the other TAG (for another CORESET pool index). Therefore, there is no need to perform operations of flushing the HARQ buffer or releasing UL channels / RS (such as PUCCH, SRS). The UE can perform the operations in Table 13 (UL OOS operations) based on the expiration of both TATs.

[0303] Proposal 5-1c_(2)

[0304] When the two tags in the UE CC / BWP are a combination of PTAG+STAG

[0305] i) When the TAT associated with PTAG expires

[0306] When the TAT associated with the PTAG expires, the UE may perform all UL OOS operations in Table 13 that should be performed based on the expiration of the PTAG TAT.

[0307] ii) When the TAT associated with the STAG expires

[0308] When the TAT associated with the STAG expires, the UE may not perform the UL OOS operations that should be performed based on the expiration of the TAT of the STAG in Table 13 except maintaining the N of this TAG. TA At least one of the operations other than the operations (defined in TS 38.211 [8]).

[0309] The above embodiment takes into account the following technical matters: Similar to what is described in Proposal 5-1c_(1), since only one TAG (STAG) of the two TAGs within the CC / BWP expires, UL transmission of the CC / BWP (for another CORESET pool index) can be performed by utilizing the TA value of the other TAG (PTAG).

[0310] Proposal 5-1c_(3)

[0311] When the two tags in the UE CC / BWP are a combination of STAG+STAG

[0312] When the two TAGs are a combination of STAG+STAG, the corresponding cell may not be PCell and / or PSCell (SpCel). When both TATs associated with the two TAGs of the corresponding cell expire, the UE may perform all UL OOS operations in Table 13 that should be performed based on the expiration of the TAT of the STAG.

[0313] When the TAT associated with one of the two TAGs expires, the UL OOS operations that should be performed based on the expiration of the TAT of the TAG in the above table may not be performed except for "maintaining the N of the TAG". TA (defined in TS 38.211 [8])". Similar to what is described in Proposal 5-1c_(1), this is because UL transmission can be performed based on the TA value of the TAG whose TAT has not expired.

[0314] Additional implementations that can be applied to Proposals 5-1a to 5-1c are described in detail below.

[0315] There may be configurations for a primary / first TRP (eg, CORESET index pool 0 and / or PTAG) and a secondary TRP (eg, CORESET pool index 1 and / or STAG) within the CC / BWP of the UE.

[0316] When the TAT of the TAG associated with the primary / first TRP expires, the UE may not perform the UL OOS operation (associated with PTAG) as shown in Table 13. The UE may perform RACH transmission (or / and SR-PUCCH transmission) for the secondary TRP.

[0317] The UE can notify the base station of the TAT expiration of the TAG associated with the main / first TRP based on RACH transmission (or / and SR-PUCCH transmission).

[0318] The base station may i) perform DL / UL transmission / reception using only the secondary TRP, or ii) perform a TA acquisition operation to maintain / update the TA value of the TAG associated with the primary / first TRP (e.g., sending a PDCCH instruction so that the UE sends a RACH for the primary / first TRP).

[0319] In the embodiments related to the above-mentioned proposals 5-1a to 5-1c and other embodiments, the following embodiments can be applied.

[0320] When the TAT of a specific TAG (e.g., PTAG or STAG) among two TAGs within a CC / BWP expires, the UE may stop sending the configured DL / UL resources associated / corresponding to the TAG (or / and the CORESET pool index connected / corresponding to the TAG), or clear the corresponding resources. As an example, the configured DL / UL resources may include at least one of the following: i) configured downlink assignment, ii) configured uplink grant, iii) and / or PUSCH resources for semi-persistent CSI reporting. According to this embodiment, when the TAT of a specific TAG among two TAGs within a CC / BWP expires, some of the UE operations performed based on the expiration of the TAT of the existing traditional PTAG / STAG are also performed. That is, since the TA value of the specific TAG (or / and the CORESET pool index connected / corresponding to the TAG) is invalid, the UE may clear the configured DL / UL resources associated with the TAG.

[0321] However, the base station can perform the same operation as Proposal 5-1a by scheduling the UE for the DL / UL resources of the dynamic component related to the TAG whose TAT expires.

[0322] In Table 8, the following operation is defined: when the timing difference between TAGs associated with a specific MAC entity exceeds the maximum uplink transmission timing difference, the MAC entity stops UL transmission. In relation to this operation, the following implementations may be considered.

[0323] According to an embodiment, a UE supporting two TAs may not perform an operation of stopping UL transmission. This embodiment takes into account the following technical matters. When two TA values ​​are managed / supported (simultaneously or in TDM form) within a specific CC / BWP of a UE, the difference between the two TAs may exceed the maximum uplink transmission timing difference.

[0324] According to an embodiment, when the difference between two TAs managed within a specific CC / BWP of the UE exceeds a maximum uplink transmission timing difference (and / or a specific threshold), the UE may operate as follows.

[0325] The UE may maintain a primary / first TA value (or / and a value associated with PTAG) and a TA timer for the corresponding TA value among the two TA values. The UE may determine that the TAT associated with the primary / first TA value (or / and a value associated with PTAG) has not expired. In addition, the UE may maintain UL transmission associated with the corresponding TA.

[0326] The UE may determine that the remaining TA value or / and the TA timer among the two TA values ​​has expired. The UE may release the UL transmission associated with the other TA value.

[0327] The implementation methods based on the above proposals 5-1c(1) and 5-1c(3) are summarized for each service cell (SpCell or SCell), as shown in Table 14 below.

[0328] [Table 14]

[0329]

[0330] Referring to Table 14, operations 1 to 8 correspond to the operations defined in Table 8 and Table 13. For example, operations 1 to 8 may be performed based on the expiration of two TATs belonging to the SpCell. For example, operations 1 to 7 may be performed based on the expiration of two TATs belonging to the SCell. Since each operation is intended to manage TRP-specific timing, the corresponding operation may be performed with respect to all TRPs (e.g., all CORESET pool indexes) of all serving cells. Here, all serving cells may mean i) all serving cells configured in the UE (in the case of SpCell) or ii) all serving cells (SCells) belonging to each TAG.

[0331] Proposal 5-2

[0332] Hereinafter, additional implementations related to 1) TRP-specific RACH transmission operations and 2) RAR MAC CE or / and timing advance command (TAC) MAC CE corresponding to RACH transmission will be studied.

[0333] In the above-mentioned Proposal 4-1, a method of performing TRP-specific (CORESET pool-specific) RACH transmission by grouping SSB is proposed. In this case, TRP-specific RACH transmission can be performed by using a specific SSB index in both RACH transmission configured by a higher layer (such as MIB) and RACH transmission instructed by PDCCH, and the same operation can be performed when CFRA (contention-free random access) transmission is (optionally) configured / indicated in both RACH transmission methods.

[0334] In addition, when CFRA transmission is configured / instructed (through PDCCH command) according to the existing scheme, CFRA resources or CBRA resources may be used. The details will be explained below.

[0335] [1] Based on the RSRP of the SSB of the SSB index configured / indicated for RACH transmission (e.g., based on the SSB index indicated by the DCI associated with the PDCCH command) being greater than a specific threshold (e.g., rsrp-ThresholdSSB), the RACH (or RA preamble) may be transmitted based on the configured / indicated SSB index. More specifically, the RACH (or RA preamble) may be transmitted based on a contention-free random access (CRFA) resource associated with the configured / indicated SSB index.

[0336] [2] Based on the RSRP of the SSB for which the SSB index is configured / indicated for RACH transmission (e.g., based on the SSB index indicated by the DCI associated with the PDCCH instruction) is less than or equal to a specific threshold (e.g., rsrp-ThresholdSSB), CBRA resources may be sent based on a fallback operation. The UE may select any SSB. RACH (or RA preamble) may be sent based on the selected SSB. More specifically, RACH (or RA preamble) may be sent based on contention-based random access (CBRA) resources associated with the selected SSB. In the case of existing schemes, it may be difficult to obtain a TRP-specific TA because RACH transmission is performed based on an arbitrary SSB. For example, another TA other than the TA for which the timer expires may be obtained from the RACH transmission. In this case, TRP-specific TA management is not efficient.

[0337] According to an embodiment, in order to solve the above problem, the operations of [1] and [2] can be widely applied to Proposal 4-1. Specifically, when CFRA transmission is configured / instructed (in RACH transmission configured by a higher layer and RACH transmission instructed by a PDCCH), the UE can operate as follows.

[0338] [1] Based on the RSRP of the SSB corresponding to the configured / indicated SSB index being greater than a specific threshold, the UE can operate in the same manner as the existing scheme. That is, RACH (or RA preamble) can be sent based on the configured / indicated SSB index.

[0339] [2] Based on the RSRP of the SSB corresponding to the configured / indicated SSB index being less than or equal to a specific threshold, the UE may operate in a manner different from the existing scheme. That is, instead of performing RACH transmission by selecting an arbitrary SSB, the UE may perform RACH (or RA preamble) transmission based on a specific SSB index. The specific SSB index may be one of the SSB indexes within the SSB group to which the configured / indicated SSB index belongs. Specifically, the UE may select any SSB (SSB index) within the SSB group that includes / corresponds to the configured / indicated SSB index, and perform RACH transmission based on the selected SSB index. RACH (or RA preamble) may be transmitted based on contention-based random access (CBRA) resources associated with the selected SSB that includes / corresponds to the configured / indicated SSB index within the SSB group.

[0340] According to the above-described embodiment, the following effects can be derived.

[0341] Even when the CFRA-related operation ([1]) falls back to the CBRA-related operation ([2]) through the RSRP-related operation, the UE can perform RACH transmission for a specific SSB group (connected to / corresponding to a specific CORESET pool index) as intended by the original BS. Through RACH transmission, the BS can obtain a TA value corresponding to the desired TRP. That is, even when the RSRP of the SSB corresponding to the SSB index indicated in association with the PDCCH instruction is less than or equal to the threshold for utilizing CFRA resources, RACH transmission can be performed based on the SSB index instead of an arbitrary SSB index to obtain a TRP-specific TA value.

[0342] According to an embodiment, for RAR for RACH transmission (RACH transmission based on a specific SSB index belonging to a specific SSB group), the following operations may be considered.

[0343] As an example, a RAR for RACH transmission associated with a specific SSB group may be sent / received using a specific RNTI (same as TRP) in a specific CSS set as in the existing scheme. In other words, when the BS (UE) receives (sends) a RACH associated with a specific SSB group, a RAR based on a specific RNTI in a specific CSS set may be sent (received).

[0344] As an example, a RAR for RACH transmission associated with a specific SSB group may be transmitted / received in a CORESET (or SS set) in which a CORESET pool index associated with a group is configured as in Proposal 4-3. In other words, when a BS (UE) receives (transmits) a RACH associated with a specific SSB group, a RAR may be transmitted (received) in a CORESET (or SS set of a CORESET) in which a CORESET pool index associated with a group is configured.

[0345] According to an embodiment, for the indication of a TA associated / corresponding to each TRP (CORESET pool index) as described in Proposal 4-3 (for example, for the indication of two TAs associated with two CORESET pool indexes), a method of indicating a TA value for each TRP may be considered.

[0346] Regarding the operation according to the implementation, the following technical matters are considered. Under the assumption of a non-ideal backhaul scenario (which is the main scenario of M-TRP based on M-DCI), dynamic level coordination between two TRPs is not performed in RAR MAC CE and / or timing advance command (TAC) MAC CE transmission. Therefore, it is necessary to indicate the TA value for each TRP. The details will be explained below.

[0347] As an example, it is possible to assume that there are two TAs within a single TAG. In this case, the following operations may be performed.

[0348] TA value indication / update may be performed for the TA value in the target TAG based on the RAR MAC CE or / and TAC MAC CE associated with each CORESET pool index.

[0349] The TA value in the target TAG may be a TA value associated / corresponding to the corresponding CORESET pool index. Alternatively, the TA value in the target TAG may be a TA value of a sub-TAG (or TASG (TA subgroup)) associated / corresponding to the corresponding CORESET pool index. TA value indication / update may be performed only for the TA value.

[0350] As an example, it can be assumed that there are two TAs in two TAGs. That is, it can be assumed that different TAs are based on different TAGs. In this case, the following operations can be performed.

[0351] TA value indication / update may be performed for a TA value corresponding to a TAG associated with a corresponding pool index based on a RAR MAC CE or / and a TAC MAC CE associated with each CORESET pool index.

[0352] In the first example (a case where there are two TAs within a single TAG) among the above examples, when a CC / BWP with a single CORESET pool is configured within a CC / BWP group (or serving cell group) constituting the TAG, there is ambiguity in UL operation as to which TA value among the two TA values ​​within the TAG should be used for UL transmission. In this case, at least one of the following operations i) and / or ii) may be performed.

[0353] i) When there is a single pool, the UE may assume the index of the pool to be 0. The UE may use the TA value associated with CORESET pool index 0 or the first TA value.

[0354] ii) The UE may utilize the set TA value. Specifically, the first TA value or the second TA value to be used in this case may be predefined / set / indicated, or may be defined / set / indicated by the BS.

[0355] In the case where there are two TAs within two TAGs as a second example, when a single CORESET pool is configured for a specific CC / BWP (or specific service cell) among the cross CC / BWP (or cross service cell) of the CC / BWP combination (service cell combination) forming the first TAG and the CC / BWP combination (service cell combination) forming the second TAG, there is ambiguity in UE operation as to which TA value among the TA values ​​through the two TAGs should be used for UL transmission. In this case, at least one of the following operations i) and / or ii) may be performed.

[0356] i) When there is a single pool, the UE may assume the index of the pool to be 0. The UE may use the TA value corresponding to the TAG associated with CORESET pool index 0, or may use the TA value corresponding to the first TAG.

[0357] ii) The UE may utilize the set TA value. Specifically, the first TAG or the second TAG to be used in this case may be pre-defined / set / indicated, or defined / set / indicated by the BS.

[0358] iii) In BS / UE configuration, it may be mandatory that the first TAG and the second TAG include the same CC / BWP combination.

[0359] In the description, the TAC MAC CE may include both an absolute TAC and a relative TAC by an offset value.

[0360] The implementations of the above proposals 1 to 5 are applicable to the M-TRP environment based on intra-cell M-DCI and the M-TRP environment based on inter-cell M-DCI. That is, the operation of performing SSB grouping by CORESET pool index to achieve TRP-specific RACH transmission in Proposals 4 and 5 can be extended to the operation of performing TRP (CORESET pool index or cell)-specific RACH transmission by dividing SSB into two groups based on the following i) and ii).

[0361] i) SSB group of the serving cell (in inter-cell M-DCI operation)

[0362] ii) Inter-cell SSB groups configured for non-serving cells (neighboring cells)

[0363] In addition, the TRP-specific RAR or / and TRP-specific TAC MAC CE operations in Proposal 4 and Proposal 5 can also be widely applied to the M-TRP environment based on inter-cell M-DCI.

[0364] The embodiments of Proposals 3 and 5 may be combined with the embodiments of Proposal 1 and the embodiments of Proposal 2 and applied to BS / UE operation, as long as these embodiments are not mutually exclusive. For example, the operation of performing two TA acquisitions without RACH enhancement (Proposal 3) and the operation of performing two TA acquisitions with RACH enhancement (Proposals 4 and Proposals 5) may not be combined, but other embodiments may be combined and applied. Specifically, the embodiment of Proposal 3 associated with two TRP-specific TA values ​​and the embodiments of Proposals 4 and 5 may be combined and applied to UE / BS operation.

[0365] Hereinafter, the signaling process based on the above-mentioned implementation manner will be described in detail.

[0366] An example of UE (or BS) operation based on at least one of the above-mentioned embodiments (for example, at least one of Proposal 1 to Proposal 5) is as follows.

[0367] 1) The UE receives (sends) unified TCI-related configuration information or / and TRP-specific TA / PC-related configuration information.

[0368] The configuration information can be based on the contents in Proposal 1 to Proposal 5.

[0369] The UE transmits (receives) SRS or / and RACH based on Proposal 3 or Proposal 5 according to the BS configuration.

[0370] The BS can receive SRS or / and RACH and measure the TRP-specific TA, and then configure / indicate the TRP-specific TA value to the UE through (RAR or / and TA command) MAC CE based on Proposal 3 or Proposal 5.

[0371] 2) The UE receives (sends) a message for scheduling TRP-specific UL transmissions.

[0372] The above message may be based on at least one of the first PDCCH (first DCI) and / or the second PDCCH (first DCI).

[0373] The message may be associated with a specific CORESET pool index and / or a specific CORESET (group).

[0374] 3) The UE uses the TRP-specific TA / PC configuration information to send (receive) UL channel / RS based on this message.

[0375] The UL channel / RS can be based on at least one of SRS, PUSCH, PUCCH or random access preamble code, and the UL channel / RS transmission can be performed based on the contents of Proposal 1 to Proposal 5.

[0376] 4) The UE can manage the TRP-specific TA timer based on the contents of Proposal 4 and Proposal 5.

[0377] The UE / BS operations are only examples, and each operation (or step) is not required, and operations related to uplink transmission using the UE's TRP-specific TA / PC according to the above-mentioned implementation may be omitted or added depending on the UE / BS implementation.

[0378] In terms of implementation, the following description can be used Figure 5 The devices (e.g., 5 and 110) process the operations of the BS / UE according to the above-mentioned embodiments (e.g., operations related to performing uplink transmission based on at least one of Proposals 1 to 5 and utilizing the UE's TRP-specific TA / PC).

[0379] In addition, the operation of the BS / UE according to the above-mentioned embodiment (for example, the operation related to performing uplink transmission using the TA / PC specific to the TRP of the terminal based on at least one of Proposals 1 to 5) can be stored in the form of instructions / programs (for example, instructions or executable codes) in a memory (for example, Figure 5 140 and 204) to drive at least one processor (e.g., Figure 5 110 and 210 in ).

[0380] The following will refer to Figure 3 and Figure 4 The above implementation is described in detail from the operation of UE and BS. The methods described below are distinguished only for convenience. It goes without saying that some components of any method can be replaced by some components of another method, or can be combined with each other for application.

[0381] Figure 3 is a flowchart describing a method performed by a UE in a wireless communication system according to an embodiment of the present disclosure.

[0382] Reference Figure 3 According to an embodiment of the present disclosure, the method performed by a UE in a wireless communication system includes a step of receiving configuration information related to a TAG (S310), a step of performing operations related to maintaining uplink time alignment (S320), and a step of sending an uplink channel / signal (S330).

[0383] In S310, the UE receives configuration information related to a timing advance group (TAG) from the BS. The configuration information may include information for a time alignment timer related to the TAG. As an example, the configuration information may be configuration information (eg, TAG-Config) based on Table 7 above.

[0384] According to an embodiment, the TAG may include a first TAG and a second TAG belonging to a serving cell. The configuration information may include information for i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG. The serving cell may be a special cell (SpCell) or a secondary cell (SCell).

[0385] According to an embodiment, each TAG may be a primary TAG (PTAG) or a secondary TAG (STAG). As an example, the first TAG may be a first PTAG, and the second TAG may be a second PTAG. As an example, the first TAG may be a first STAG, and the second TAG may be a second STAG.

[0386] In S320, the UE performs operations related to maintaining uplink time alignment based on the time alignment timer. Specifically, the UE may perform operations defined in Table 8. As an example, the UE may perform operations based on whether the time alignment timer expires.

[0387] According to an embodiment, the OOS operation based on Table 13 may be performed based on both time alignment timers expiring. This embodiment may be based on Proposal 5-1c.

[0388] Specifically, based on the expiration of the first time alignment timer and the second time alignment timer, the following operations may be performed:

[0389] i) flush all HARQ buffers,

[0390] ii) releasing the configured Physical Uplink Control Channel (PUCCH),

[0391] iii) releasing the configured sounding reference signal (SRS),

[0392] iv) clearing configured downlink assignments and configured uplink grants,

[0393] v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and

[0394] vi) Maintain N for each TAG TA .

[0395] As an example, the above operations i) to vi) may be performed for all TRPs (eg, all CORESET pool indexes) of all serving cells.

[0396] In addition, when both time alignment timers expire, the UE may not even perform uplink transmission for any serving cell. As an example, based on the expiration of the first time alignment timer and the second time alignment timer, any uplink transmission other than random access preamble transmission and MsgA transmission may not be performed. Random access preamble transmission and MsgA transmission may be related to SpCell or SCell.

[0397] The UE may transmit an uplink channel / signal while at least one of the first time alignment timer and the second time alignment timer is running. For example, uplink transmission may mean uplink transmission associated with all serving cells (e.g., when the serving cell is a SpCell). For example, uplink transmission may be uplink transmission associated with a serving cell belonging to a first TAG and a serving cell belonging to a second TAG (e.g., when the serving cell is a SCell).

[0398] For example, when only one of the two time alignment timers expires, at least one of operations i) to vi) may not be performed. In other words, when only one of the two time alignment timers expires, at least one of operations i) to vi) (or at least one of operations 1 to 7 in Table 14) may not be performed. Specifically, based on the expiration of the first time alignment timer or the second time alignment timer, at least one of operations i) to vi) may be performed.

[0399] At this time, at least one of operations i) to vi) may be performed at the TRP level. As an example, at least one of operations i) to vi) may be performed for a transmission and reception point (TRP) associated with an expired timer (or at least one of operations 1 to 7 in Table 14). As an example, at least one of operations i) to vi) may be performed based on a CORESET pool index associated with an expired timer. As an example, at least one of operations i) to vi) may be performed for a TAG associated with an expired timer.

[0400] In addition, based on the expiration of the first time alignment timer or the second time alignment timer, any uplink transmission other than random access preamble transmission and MsgA transmission may not be performed. At this time, uplink transmission may mean uplink transmission for TRP associated with the expired uplink alignment timer or uplink transmission based on TAG associated with the expired uplink alignment timer. That is, the UE may perform uplink transmission based on the uplink timing for the TAG associated with the unexpired uplink alignment timer.

[0401] N TA Can be related to the calculation of timing advance (TA). TA It can be based on the description in Table 1.

[0402] According to an implementation, the first TAG / second TAG may be a PTAG. In this case, an operation based on Proposal 5-1c_(1) may be performed. Specifically, based on the first TAG being the first PTAG and the second TAG being the second PTAG, operations i) to vi) performed when the first time alignment timer and the second time alignment timer expire may be performed for all serving cells, and all running time alignment timers may be deemed to have expired.

[0403] In addition, the UE may not perform any uplink transmission except random access preamble transmission and MsgA transmission for all serving cells or the serving cells.

[0404] According to the implementation method, the first TAG / second TAG may be a STAG. In this case, an operation based on Proposal 5-1c_(3) may be performed. Specifically, based on the fact that the first TAG is a first STAG and the second TAG is a second STAG, operations i) to vi) performed when the first time alignment timer and the second time alignment timer expire may be performed for a service cell belonging to the first STAG and a service cell belonging to the second STAG.

[0405] In addition, the UE may not perform any uplink transmission except for the random access preamble code transmission and the MsgA transmission for the serving cell belonging to the first STAG and the serving cell belonging to the second STAG.

[0406] According to an implementation, when only one of the two time alignment timers expires, information about the expired time alignment timer may be reported. Specifically, the method may further include the step of sending information related to the expired time alignment timer. Based on the expiration of the first time alignment timer or the second time alignment timer, the UE may send information related to the expired time alignment timer to the base station. This implementation may be based on Proposal 5-1b. The step of sending information related to the expired time alignment timer may be performed before S330.

[0407] Information related to the expired time alignment timer may include at least one of the following: i) an ID of the first TAG or the second TAG, ii) a first CORESET pool index associated with the first TAG or a second CORESET pool index associated with the second TAG, and / or iii) an ID of a transmit and receive point (TRP) associated with the first TAG or the second TAG.

[0408] Information related to an expired time alignment timer may be sent based on the first uplink resource or the second uplink resource. The first uplink resource may be related to the expiration of the first time alignment timer. The second uplink resource may be related to the expiration of the second time alignment timer.

[0409] The first uplink resource may be associated with the second CORESET pool index. The second uplink resource may be associated with the first CORESET pool index.

[0410] That is, the first uplink resource / second uplink resource can be a resource in which information related to a beam pointing to a TRP associated with a TAG for which the time alignment timer has not expired is configured. As an example, based on the expiration of the first time alignment timer (second time alignment timer) associated with the first TRP (second TRP), the UE can send information related to the expired time alignment timer based on the spatial domain transmit filter associated with the second uplink resource (first uplink resource). The spatial domain transmit filter associated with the second uplink resource (first uplink resource) can be determined based on information (UL TCI state and joint TCI state) related to the second CORESET pool index (first CORESET pool index).

[0411] In S330 , the UE transmits an uplink channel / signal based on the uplink transmission timing for the TAG to the base station.

[0412] According to an embodiment, the uplink channel / signal may refer to an uplink channel / signal configured / scheduled by a base station. Specifically, the uplink channel / signal may include i) a first uplink channel / signal transmitted based on uplink timing for a first TAG and / or ii) a second uplink channel / signal transmitted based on uplink timing for a second TAG.

[0413] The first uplink channel / signal may be i) a first PUSCH, ii) a first PUCCH, or iii) a first SRS. The second uplink channel / signal may be i) a second PUSCH, ii) a second PUCCH, or iii) a second SRS.

[0414] According to an embodiment, the operation based on Proposal 5-1a may be performed based on the expiration of one of the two time alignment timers. Hereinafter, the above operation will be described in detail.

[0415] As an example, the base station may not configure / schedule the UL channel / RS related to the expired time alignment timer to the UE. This implementation may be based on Proposal 5-1a. Specifically, based on the expiration of the first time alignment timer or the second time alignment timer, the uplink channel / signal may be the second uplink channel / signal or the first uplink channel / signal.

[0416] As an example, among the uplink channels / signals configured / scheduled by the base station, the uplink channels / signals associated with the expired time alignment timer can be discarded. Specifically, based on the expiration of the first time alignment timer or the second time alignment timer, the first uplink channel / signal or the second uplink channel / signal can be discarded.

[0417] As an example, the UE may also send a UL channel / RS associated with an expired time alignment timer. That is, the base station may receive a UL channel / RS associated with two time alignment timers from the UE. Afterwards, the base station may send a MACCE to the UE to perform a timing adjustment on the TAG associated with the expired time alignment timer. Specifically, the method may further include a MACCE receiving step. The MAC CE receiving step may be performed before S330.

[0418] Based on i) the expiration of the first time alignment timer or the second time alignment timer, and ii) the first uplink channel / signal and the second uplink channel / signal are transmitted, the UE receives a timing advance command medium access control (MAC) control element (CE) (MAC CE) from the base station. The timing advance command MAC CE can be related to the first TAG or the second TAG.

[0419] Timing Advance Command MAC CE (e.g. Figure 2) includes a timing advance command field. The timing advance command field indicates an index related to the timing adjustment (see Figure 1 , Table 4 and Table 5). The index related to the timing adjustment may refer to the index value TA of Table 4 and Table 5. N for calculating the timing advance (TA) may be indicated based on the index related to the timing adjustment. TA TA may refer to T in Table 1 TA . The TA may be a TRP-specific TA (e.g., a first TA or a second TA). Specifically, the TA may be associated with a first TAG or a second TAG.

[0420] As an example, the UE may also send a UL channel / RS associated with an expired time alignment timer. That is, the base station may receive a UL channel / RS associated with two time alignment timers from the UE. The base station may instruct the UE to initiate a RACH process to obtain a new TA value for the TAG associated with the expired time alignment timer. Specifically, the method may further include a step of receiving DCI. The step of receiving DCI may be performed after S330.

[0421] Based on i) the expiration of the first time alignment timer or the second time alignment timer, and ii) the first uplink channel / signal and the second uplink channel / signal are sent, the UE receives downlink control information (DCI) from the base station. The DCI includes information related to the physical downlink control channel (PDCCH) command. The random access procedure can be initiated by the PDCCH command.

[0422] The DCI may include a synchronization signal / physical broadcast channel block index (SSB index) associated with the PDCCH instruction. Here, the SSB index may be an SS / PBCH index of an SS / PBCH block. The SSB index associated with the PDCCH instruction may be included in i) a first SSB group associated with a first CORESET pool index, and ii) a second SSB group associated with a second CORESET pool index. Each SSB group may be a group based on Proposal 4-1 above. As an example, the first SSB group may include one or more first SSBs belonging to SSB indices 0 to 31, and the second SSB group may include one or more second SSBs belonging to SSB indices 32 to 63.

[0423] For example, the DCI may be DCI format 1_0. DCI format 1_0 may include an SS / PBCH index field. The SS / PBCH index field may indicate an SS / PBCH (or SSB index) for determining a RACH timing for PRACH transmission (ie, random access preamble transmission).

[0424] As an example, the random access procedure may be initiated by a PDCCH command to establish a timing advance for the first TAG or the second TAG.For example, the random access procedure may be a type 1 random access procedure (4-step RA) or a type 2 random access procedure (2-step RA).

[0425] The type 1 random access procedure may include sending a random access preamble (Msg1) on a physical random access channel (PRACH), receiving a random access response (RAR) (Msg2), sending a PUSCH (Msg3) scheduled by a UL grant of the RAR, and sending a PDSCH (Msg4) for contention resolution. When the random access procedure is a contention-free random access (CFRA), the Msg3 sending and Msg4 receiving operations are omitted.

[0426] The type 2 random access procedure may include sending a random access preamble and PUSCH (MsgA) and receiving a RAR (MsgB).

[0427] The method may also include a random access preamble sending step. In this step, the UE sends a random access preamble to the base station. The random access preamble may be sent based on a random access procedure (e.g., 4-step RA or 2-step RA) initiated by a PDCCH instruction. As an example, the random access preamble may be based on Msg1 of a type-1 random access procedure or MsgA of a type-2 random access procedure. The random access preamble sending step may be performed after S330.

[0428] According to an embodiment, the random access preamble may be sent based on an SSB index associated with a PDCCH command or a specific SSB index. This embodiment may be based on the above-mentioned proposal 5-2.

[0429] According to an embodiment, a UE supporting two TAGs belonging to a serving cell may not perform operations related to the maximum uplink transmission timing difference in Table 8. That is, this is because the timing difference between the TAGs related to the TRP may exceed the maximum uplink transmission timing difference. Specifically, regardless of whether the timing difference between the first TAG and the second TAG exceeds the maximum uplink transmission timing difference related to stopping uplink transmission, the uplink channel / signal may be transmitted.

[0430] The method may also include the step of receiving configuration information related to CORESET. Specifically, the UE receives configuration information related to multiple control resource sets (CORESETs) from the base station. The CORESET based on the first CORESET pool index and the second CORESET pool index may be configured based on the configuration information related to the CORESET.

[0431] The step of receiving configuration information related to CORESET may be performed before S310.

[0432] According to an embodiment, the first TAG may be associated with a first CORESET pool index and the second TAG may be associated with a second CORESET pool index.

[0433] The above operations based on S310 to S330, the step of sending information related to the expired time alignment timer, the step of receiving the MAC CE, the step of receiving the DCI, the step of sending the random access preamble, and the step of receiving the configuration information related to the CORESET can be performed by Figure 5 For example, the UE 200 may control one or more transceivers 230 and / or one or more memories 240 to perform operations based on S310 to S330, a step of sending information related to an expired time alignment timer, a MAC CE receiving step, a DCI receiving step, a random access preamble sending step, and a step of receiving configuration information related to a CORESET.

[0434] Hereinafter, the above-mentioned embodiments will be described in detail from the perspective of the operation of the base station.

[0435] The steps S410 to S420 described below, the step of receiving information related to the expired time alignment timer, the step of sending MAC CE, the step of sending DCI, the step of receiving the random access preamble code, the step of sending the configuration information related to CORESET and the step of Figure 3 The steps S310 to S330 described in the above, the step of sending information related to the expired time alignment timer, the step of receiving the MAC CE, the step of receiving the DCI, the step of sending the random access preamble, and the step of receiving the configuration information related to the CORESET correspond to each other. By considering the corresponding relationship, redundant descriptions are omitted. That is, the specific description of the base station operation described below can be used in accordance with the corresponding operation. Figure 3 The description / implementation method is replaced by .

[0436] As an example, Figure 3 The description / implementation of S310 to S330 may be additionally applied to the base station operations of S410 and S420 described below.

[0437] As an example, the description / implementation of the steps of sending information related to an expired time alignment timer, the MAC CE receiving step, the DCI receiving step, the random access preamble sending step, and the step of receiving configuration information related to CORESET can be additionally applied to the base station operations of the steps of receiving information related to an expired time alignment timer, the MAC CE sending step, the DCI sending step, the random access preamble receiving step, and the step of sending configuration information related to CORESET described below.

[0438] Figure 4 is a flowchart for describing a method performed by a base station in a wireless communication system according to another embodiment of the present disclosure.

[0439] Reference Figure 4 , a method performed by a BS in a wireless communication system according to another embodiment of the present disclosure includes a step of transmitting configuration information related to a TAG (S410) and a step of receiving an uplink channel / signal (S420).

[0440] In S410, the base station sends configuration information related to a timing advance group (TAG) to the UE. The UE performs operations related to maintaining uplink time alignment based on the time alignment timer.

[0441] The method may further include a step of receiving information related to an expired time alignment timer. Based on the expiration of the first time alignment timer or the second time alignment timer, the base station may receive information related to the expired time alignment timer from the UE. The step of receiving information related to the expired time alignment timer may be performed after S410 or before S420.

[0442] In S420, the base station receives an uplink channel / signal transmitted based on the uplink transmission timing for the TAG from the UE.

[0443] The method may further include a MAC CE sending step. The MAC CE sending step may be performed after S420.

[0444] Based on i) expiration of the first time alignment timer or the second time alignment timer and ii) the first uplink channel / signal and the second uplink channel / signal being received, the base station sends a timing advance command medium access control (MAC) control element (CE) (MAC CE) to the UE.

[0445] The method may further include a DCI sending step. The DCI sending step may be performed after S420.

[0446] Based on i) expiration of the first time alignment timer or the second time alignment timer, and ii) the first uplink channel / signal and the second uplink channel / signal being received, the base station transmits downlink control information (DCI) to the UE.

[0447] The method may further include a random access preamble receiving step. In the above steps, the base station receives a random access preamble from the UE. The random access preamble receiving step may be performed after S420.

[0448] The method may also include the step of sending configuration information related to the CORESET. Specifically, the base station sends configuration information related to multiple control resource sets (CORESETs) to the UE. The CORESET based on the first CORESET pool index and the second CORESET pool index may be configured based on the configuration information related to the CORESET.

[0449] The step of sending configuration information related to CORESET may be performed before S410.

[0450] The above-mentioned operations based on S410 and 420, the step of receiving information related to the expired time alignment timer, the step of sending MAC CE, the step of sending DCI, the step of receiving the random access preamble code, and the step of sending the configuration information related to CORESET can be performed by Figure 5 For example, the base station 100 may control one or more transceivers 130 and / or one or more memories 140 to perform operations based on S410 and S420, a step of receiving information related to an expired time alignment timer, a MAC CE sending step, a DCI sending step, a random access preamble receiving step, and a step of sending configuration information related to a CORESET.

[0451] Refer to the following Figure 5 The following describes a device to which the embodiments of the present disclosure are applicable (a device that implements the method / operation according to the embodiments of the present disclosure).

[0452] Figure 5 The configurations of the first device and the second device according to the embodiment of the present disclosure are illustrated.

[0453] The first device 100 may include a processor 110 , an antenna unit 120 , a transceiver 130 , and a memory 140 .

[0454] The processor 110 may perform signal processing related to the baseband, and includes a high-level processing unit 111 and a physical layer processing unit 115. The high-level processing unit 111 may process operations of a MAC layer, an RRC layer, or a higher layer. The physical layer processing unit 115 may process operations of a PHY layer. For example, if the first device 100 is a base station (BS) device in BS-UE communication, the physical layer processing unit 115 may perform uplink received signal processing, downlink transmitted signal processing, etc. For example, if the first device 100 is a first UE device in inter-UE communication, the physical layer processing unit 115 may perform downlink received signal processing, uplink transmitted signal processing, sidelink transmitted signal processing, etc. In addition to performing signal processing related to the baseband, the processor 110 may also control the overall operation of the first device 100.

[0455] The antenna unit 120 may include one or more physical antennas, and if the antenna unit 120 includes multiple antennas, MIMO transmission / reception is supported. The transceiver 130 may include a radio frequency (RF) transmitter and an RF receiver. The memory 140 may store information processed by the processor 110 and software, an operating system, and applications related to the operation of the first device 100. The memory 140 may also include components such as a buffer.

[0456] In the embodiments described in the present disclosure, the processor 110 of the first device 100 may be configured to implement operations of a BS in BS-UE communication (or operations of a first UE device in inter-UE communication).

[0457] The second device 200 may include a processor 210 , an antenna unit 220 , a transceiver 230 , and a memory 240 .

[0458] The processor 210 may perform signal processing related to the baseband, and includes a high-level processing unit 211 and a physical layer processing unit 215. The high-level processing unit 211 may process operations of a MAC layer, an RRC layer, or a higher layer. The physical layer processing unit 215 may process operations of a PHY layer. For example, if the second device 200 is a UE device in BS-UE communication, the physical layer processing unit 215 may perform downlink received signal processing, uplink transmitted signal processing, etc. For example, if the second device 200 is a second UE device in inter-UE communication, the physical layer processing unit 215 may perform downlink received signal processing, uplink transmitted signal processing, side link received signal processing, etc. In addition to performing signal processing related to the baseband, the processor 210 may also control the overall operation of the second device 200.

[0459] The antenna unit 220 may include one or more physical antennas, and if the antenna unit 220 includes multiple antennas, MIMO transmission / reception is supported. The transceiver 230 may include an RF transmitter and an RF receiver. The memory 240 may store information processed by the processor 210 and software, operating systems, and applications related to the operation of the second device 200. The memory 240 may also include components such as a buffer.

[0460] In the embodiments described in the present disclosure, the processor 210 of the second device 200 may be configured to implement operations of a UE in BS-UE communication (or operations of a second UE device in inter-UE communication).

[0461] The description of the BS and the UE in BS-UE communication (or the first UE device and the second UE device in inter-UE communication) in the examples of the present disclosure are equally applicable to the operations of the first device 100 and the second device 200, and redundant descriptions are omitted.

[0462] In addition to LTE, NR, and 6G, the wireless communication technology implemented in the apparatus 100 and the apparatus 200 according to the present disclosure may also include a narrowband Internet of Things (NB-IoT) for low-power communication. For example, the NB-IoT technology may be an example of a low-power wide area network (LPWAN) technology and may be implemented in standards such as LTE Cat NB1 and / or LTE Cat NB2. The NB-IoT technology is not limited to the above names.

[0463] Additionally or alternatively, the wireless communication technology implemented in the apparatus 100 and the apparatus 200 according to the present disclosure may perform communication based on the LTE-M technology. For example, the LTE-M technology may be an example of the LPWAN technology and may be referred to as various names, such as enhanced machine type communication (eMTC). For example, the LTE-M technology may be implemented with at least one of various standards, such as 1) LTE CAT0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-bandwidth limited), 5) LTE-MTC, 6) LTE machine type communication and / or 7) LTE M. The LTE-M technology is not limited to the above names.

[0464] Additionally or alternatively, in consideration of low power communication, the wireless communication technology implemented in the apparatus 100 and the apparatus 200 according to the present disclosure may include at least one of ZigBee, Bluetooth, and a low power wide area network (LPWAN), and is not limited to the above names. For example, ZigBee technology may create a personal area network (PAN) related to small / low power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

Claims

1. A method performed by a user equipment UE in a wireless communication system, the method comprising the following steps: Receiving configuration information related to a timing advance group TAG from a base station, wherein the configuration information includes information for a time alignment timer related to the TAG; performing operations associated with maintaining uplink timing alignment based on the time alignment timer; and transmitting an uplink channel / signal to the base station based on the uplink transmission timing for the TAG, The TAG includes a first TAG and a second TAG belonging to a serving cell, The configuration information includes information about i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG, Each TAG is either a primary TAG PTAG or a secondary TAG STAG, and Wherein, based on the expiration of the first time alignment timer and the second time alignment timer, performing the following operations: i) flush all HARQ buffers, ii) releasing the configured physical uplink control channel PUCCH, iii) releasing the configured sounding reference signal SRS, iv) clearing configured downlink assignments and configured uplink grants, v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) Maintain N for each TAG TA .

2. The method according to claim 1, wherein: Based on the expiration of the first time alignment timer and the second time alignment timer, uplink transmission other than random access preamble transmission and MsgA transmission is not performed.

3. The method according to claim 1, further comprising the steps of: Receive configuration information related to multiple control resource sets CORESET, Wherein, a CORESET based on a first CORESET pool index and a second CORESET pool index is configured based on the configuration information related to the CORESET.

4. The method according to claim 3, wherein: The first TAG is associated with the first CORESET pool index, and the second TAG is associated with the second CORESET pool index.

5. The method according to claim 1, further comprising the steps of: Based on the expiration of the first time alignment timer or the second time alignment timer, information related to the expired time alignment timer is sent.

6. The method according to claim 5, wherein: The information related to the expired time alignment timer includes at least one of the following: i) the ID of the first TAG or the second TAG, ii) the first CORESET pool index related to the first TAG or the second CORESET pool index related to the second TAG, and / or iii) the ID of the transmitting and receiving point TRP associated with the first TAG or the second TAG.

7. The method according to claim 5, wherein: The information related to the expired time alignment timer is sent based on the first uplink resource or the second uplink resource, wherein the first uplink resource is associated with expiration of the first time alignment timer, and the second uplink resource is associated with expiration of the second time alignment timer, and The first uplink resource is associated with a second CORESET pool index, and the second uplink resource is associated with a first CORESET pool index.

8. The method according to claim 1, wherein: The uplink channel / signal includes i) a first uplink channel / signal transmitted based on uplink timing for the first TAG and / or ii) a second uplink channel / signal transmitted based on uplink timing for the second TAG.

9. The method according to claim 8, wherein: The first uplink channel / signal is i) a first PUSCH, ii) a first PUCCH, or iii) a first SRS, and The second uplink channel / signal is i) a second PUSCH, ii) a second PUCCH, or iii) a second SRS.

10. The method according to claim 8, wherein: Based on expiration of the first time alignment timer or the second time alignment timer, the first uplink channel / signal or the second uplink channel / signal is dropped.

11. The method according to claim 8, further comprising the steps of: receiving a timing advance command medium access control MAC control element CE MAC CE based on i) expiration of the first time alignment timer or the second time alignment timer, and ii) the first uplink channel / signal and the second uplink channel / signal being transmitted, The timing advance command MAC CE is related to the first TAG or the second TAG.

12. The method according to claim 8, further comprising the steps of: receiving downlink control information DCI based on i) expiration of the first time alignment timer or the second time alignment timer, and ii) the first uplink channel / signal and the second uplink channel / signal being transmitted, The DCI includes information related to a physical downlink control channel PDCCH instruction, and a random access process is initiated through the PDCCH instruction.

13. The method according to claim 8, wherein: Based on expiration of the first time alignment timer or the second time alignment timer, the uplink channel / signal is the second uplink channel / signal or the first uplink channel / signal.

14. The method according to claim 1, wherein: Based on the first TAG being the first PTAG and the second TAG being the second PTAG, the operations i) to vi) performed based on the expiration of the first time alignment timer and the second time alignment timer are performed for all service cells, and all running time alignment timers are considered expired.

15. The method according to claim 1, wherein: Based on the first TAG being a first STAG and the second TAG being a second STAG, the operations i) to vi) performed based on the expiration of the first time alignment timer and the second time alignment timer are performed on a serving cell belonging to the first STAG and a serving cell belonging to the second STAG.

16. The method according to claim 1, wherein: The uplink channel / signal is transmitted regardless of whether the timing difference between the first TAG and the second TAG exceeds a maximum uplink transmission timing difference associated with the stop of uplink transmission.

17. The method according to claim 1, wherein: The N TA Related to the calculation of timing advance TA.

18. The method according to claim 1, wherein: The serving cell is a special cell SpCell or a secondary cell SCell.

19. The method according to claim 1, wherein: Based on expiration of the first time alignment timer or the second time alignment timer, at least one of the operations i) to vi) is performed.

20. A user equipment UE operating in a wireless communication system, the UE comprising: one or more transceivers; one or more processors; as well as one or more memories operatively connectable to the one or more processors and storing instructions that upon execution by the one or more processors configure the one or more processors to perform operations, The operations include: receiving configuration information related to a timing advance group TAG from a base station, wherein the configuration information includes information for a time alignment timer related to the TAG, performing operations associated with maintaining uplink timing alignment based on the time alignment timer, and transmitting an uplink channel / signal to the base station based on the uplink transmission timing for the TAG, The TAG includes a first TAG and a second TAG belonging to a serving cell, The configuration information includes information about i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG, Each TAG is either a primary TAG PTAG or a secondary TAG STAG, and Wherein, based on the expiration of the first time alignment timer and the second time alignment timer, performing the following operations: i) flush all HARQ buffers, ii) releasing the configured physical uplink control channel PUCCH, iii) releasing the configured sounding reference signal SRS, iv) clearing configured downlink assignments and configured uplink grants, v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) Maintain N for each TAG TA .

21. A device, comprising: one or more memories, and one or more processors functionally connected to the one or more memories, wherein the one or more memories include instructions that upon execution by the one or more processors configure the one or more processors to perform operations, and The operations include: receiving configuration information related to a timing advance group TAG from a base station, wherein the configuration information includes information for a time alignment timer related to the TAG, performing operations associated with maintaining uplink timing alignment based on the time alignment timer, and transmitting an uplink channel / signal to the base station based on the uplink transmission timing for the TAG, The TAG includes a first TAG and a second TAG belonging to a serving cell, The configuration information includes information about i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG, Each TAG is either a primary TAG PTAG or a secondary TAG STAG, and Wherein, based on the expiration of the first time alignment timer and the second time alignment timer, performing the following operations: i) flush all HARQ buffers, ii) releasing the configured physical uplink control channel PUCCH, iii) releasing the configured sounding reference signal SRS, iv) clearing configured downlink assignments and configured uplink grants, v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) Maintain N for each TAG TA .

22. One or more non-transitory computer-readable media storing one or more instructions, wherein: The one or more instructions executable by one or more processors configure the one or more processors to perform operations, and The operations include: receiving configuration information related to a timing advance group TAG from a base station, wherein the configuration information includes information for a time alignment timer related to the TAG, performing operations associated with maintaining uplink timing alignment based on the time alignment timer, and transmitting an uplink channel / signal to a base station based on the uplink transmission timing for the TAG, The TAG includes a first TAG and a second TAG belonging to a serving cell, The configuration information includes information about i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG, Each TAG is either a primary TAG PTAG or a secondary TAG STAG, and Wherein, based on the expiration of the first time alignment timer and the second time alignment timer, performing the following operations: i) flush all HARQ buffers, ii) releasing the configured physical uplink control channel PUCCH, iii) releasing the configured sounding reference signal SRS, iv) clearing configured downlink assignments and configured uplink grants, v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) Maintain N for each TAG TA .

23. A method performed by a base station in a wireless communication system, the method comprising the following steps: Sending configuration information related to a timing advance group TAG to a user equipment UE, wherein the configuration information includes information for a time alignment timer related to the TAG, The UE performs operations related to maintaining uplink timing alignment based on the time alignment timer; and receiving, from the UE, an uplink channel / signal transmitted based on the uplink transmission timing for the TAG, The TAG includes a first TAG and a second TAG belonging to a serving cell, The configuration information includes information about i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG, Each TAG is either a primary TAG PTAG or a secondary TAG STAG, and Wherein, based on the expiration of the first time alignment timer and the second time alignment timer, the UE performs the following operations: i) flush all HARQ buffers, ii) releasing the configured physical uplink control channel PUCCH, iii) releasing the configured sounding reference signal SRS, iv) clearing configured downlink assignments and configured uplink grants, v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) Maintain N for each TAG TA .

24. A base station operating in a wireless communication system, the base station comprising: one or more transceivers; one or more processors; as well as one or more memories operatively connectable to the one or more processors and storing instructions that upon execution by the one or more processors configure the one or more processors to perform operations, The operations include: Sending configuration information related to a timing advance group TAG to a user equipment UE, wherein the configuration information includes information for a time alignment timer related to the TAG, The UE performs operations related to maintaining uplink timing alignment based on the time alignment timer; and receiving, from the UE, an uplink channel / signal transmitted based on the uplink transmission timing for the TAG, The TAG includes a first TAG and a second TAG belonging to a serving cell, The configuration information includes information about i) a first time alignment timer associated with the first TAG and ii) a second time alignment timer associated with the second TAG, Each TAG is either a primary TAG PTAG or a secondary TAG STAG, and Wherein, based on the expiration of the first time alignment timer and the second time alignment timer, the UE performs the following operations: i) flush all HARQ buffers, ii) releasing the configured physical uplink control channel PUCCH, iii) releasing the configured sounding reference signal SRS, iv) clearing configured downlink assignments and configured uplink grants, v) clearing the Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting, and vi) Maintain N for each TAG TA .

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