Support for mobility based on l1 and l2 signaling

Abstract

Methods and apparatus for support of mobility based on L1 and L2 signaling are disclosed. In one embodiment, a UE comprises: a transceiver; and a processor coupled to the transceiver wherein the processor is configured to receive, via the transceiver, a DCI or MAC CE indicating a serving cell change command for a target cell; and applying the target cell as a new serving cell after the HARQ-ACK information for the DCI or the MAC CE is transmitted via the transceiver.

Description

Technical Field

[0001] The subject matter disclosed herein relates generally to wireless communications, and more particularly to methods and apparatus for support of mobility based on L1 and L2 signaling. Background Art

[0002] The following abbreviations are defined herein, at least some of which are referred to within the following description: New Radio (NR), Very Large Scale Integration (VLSI), Random Access Memory (RAM), Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM or Flash), Compact Disk Read Only Memory (CD-ROM), Local Area Network (LAN), Wide Area Network (WAN), User Equipment (UE), Evolved Node B (eNB), Next Generation Node B (gNB), Uplink (UL), Downlink (DL), Central Processing Unit (CPU), Graphics Processing Unit (GPU), Field Programmable Gate Array (FPGA), Orthogonal Frequency Division Multiplexing (OFDM), Radio Resource Control (RRC), User Entity / Equipment (Mobile Terminal), Transmitter (TX), Receiver (RX), Layer 1 (L1), Layer 2 (L2), Layer 3 (L3), Primary Cell (PCell), Secondary Cell (SCell), Primary Secondary Cell (PSCell) ll), downlink control information (DCI), medium access control (MAC), control element (CE), transmission configuration indication (TCI), physical cell identity (PCI), synchronization signal block (SSB), bandwidth part (BWP), radio network temporary identifier (RNTI), hybrid automatic repeat request (HARQ), acknowledgement (ACK), subcarrier space (SCS), physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), physical downlink control channel (PDCCH), physical downlink shared channel (PDSCH), channel state information (CSI), CSI reference signal (CSI-RS), CSI-RS resource indicator (CRI), quasi co-location (QCL), channel measurement resource (CMR), SSB resource indicator (SSBRI), reference signal received power (RSRP), timing advance (TA), transmit reception point (TRP), TA group (TAG).

[0003] When a UE moves from the coverage of one cell to another, a serving cell change needs to be performed. Currently, serving cell changes are triggered by L3 (Layer 3, corresponding to the RRC layer) measurements and are done through reconfiguration with synchronization triggered by RRC signaling. Serving cell changes include changes in PCell and PSCell, as well as releasing and adding SCells when applicable. Measurements and changes involve a complete L2 (Layer 2, corresponding to the MAC layer) and L1 (Layer 1, corresponding to the physical layer) reset, resulting in longer latency, greater overhead, and longer interruption time than beam switching mobility.

[0004] The present invention targets mobility delay reduction, and in particular, enables serving cell change via L1 and L2 signaling. Summary of the invention

[0005] Methods and apparatus for support of mobility based on L1 and L2 signaling are disclosed.

[0006] In one embodiment, the UE includes a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to receive a DCI or MAC CE indicating a serving cell change command for a target cell via the transceiver; and apply the target cell as a new serving cell after sending HARQ-ACK information for the DCI or MAC CE via the transceiver.

[0007] In some embodiments, the DCI indicates a unified TCI state from two or more TCI states that are activated, wherein the unified TCI state is associated with an SSB associated with a physical cell ID that identifies one of the candidate target cells, and the serving cell change command indicates to apply the target cell that is one of the candidate target cells. For example, the DCI is a DCI with format 1_1 or 1_2 including a new field indicating a serving cell change command, or a DCI with format 1_1 or 1_2 without DL assignment including a reserved field indicating a serving cell change command.

[0008] In some embodiments, the MAC CE activates a unified TCI state, wherein the unified TCI state is associated with the SSB associated with the physical cell ID identifying one of the candidate target cells, and the serving cell change command indicates to apply the target cell as one of the candidate target cells.

[0009] In some embodiments, the DCI indicates a physical cell ID of one of the candidate target cells as a serving cell change command, and the serving cell change command indicates to apply the target cell as one of the candidate target cells. For example, the DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

[0010] In some embodiments, the processor is configured to apply the target cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via the UE capability report per SCS.

[0011] In some embodiments, the processor is further configured to receive all PDCCHs and PDSCHs with a unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0012] In some embodiments, the processor is further configured to receive a CSI report configuration via the transceiver; and send a beam report via the transceiver including one or more beam indices with the measured L1-RSRP, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cell is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

[0013] In some embodiments, the DCI or MAC CE further indicates a TAG ID. Alternatively, a unified TCI state or a physical cell ID identifying a target cell is associated with the TAG ID.

[0014] In another embodiment, a method performed at a UE includes receiving a DCI or a MAC CE indicating a serving cell change command for a target cell; and applying the target cell as a new serving cell after sending HARQ-ACK information for the DCI or the MAC CE.

[0015] In yet another embodiment, the base station unit includes a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to send a DCI or MAC CE indicating a serving cell change command for a target cell via the transceiver; and apply the target cell as a new serving cell after receiving HARQ-ACK information for the DCI or MAC CE via the transceiver.

[0016] In some embodiments, the DCI indicates a unified TCI state from two or more TCI states that are activated, wherein the unified TCI state is associated with an SSB associated with a physical cell ID that identifies one of the candidate target cells, and the serving cell change command indicates to apply the target cell that is one of the candidate target cells. For example, the DCI is a DCI with format 1_1 or 1_2 including a new field indicating a serving cell change command, or a DCI with format 1_1 or 1_2 without DL assignment including a reserved field indicating a serving cell change command.

[0017] In some embodiments, the MAC CE activates a unified TCI state, wherein the unified TCI state is associated with the SSB associated with the physical cell ID identifying one of the candidate target cells, and the serving cell change command indicates to apply the target cell as one of the candidate target cells.

[0018] In some embodiments, the DCI indicates a physical cell ID of one of the candidate target cells as a serving cell change command, and the serving cell change command indicates to apply the target cell as one of the candidate target cells. For example, the DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

[0019] In some embodiments, the processor is configured to apply the target cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via the UE capability report per SCS.

[0020] In some embodiments, the processor is further configured to send all PDCCHs and PDSCHs with a unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0021] In some embodiments, the processor is further configured to send a CSI report configuration via the transceiver; and receive a beam report via the transceiver including one or more beam indices with measured L1-RSRP, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cell is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

[0022] In some embodiments, the DCI or MAC CE further indicates a TAG ID. Alternatively, a unified TCI state or a physical cell ID identifying a target cell is associated with the TAG ID.

[0023] In yet another embodiment, a method performed at a base station unit includes sending a DCI or MAC CE indicating a serving cell change command for a target cell; and applying the target cell as a new serving cell after receiving HARQ-ACK information for the DCI or MAC CE. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments illustrated in the accompanying drawings. Understanding that these drawings depict only some embodiments and are therefore not to be considered limiting in scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0025] Figure 1 An example of a first sub-embodiment of the second embodiment is illustrated;

[0026] Figure 2 is a schematic flow chart illustrating an embodiment of a method;

[0027] Figure 3 is a schematic flow chart illustrating an embodiment of another method; and

[0028] Figure 4 is a schematic block diagram illustrating an apparatus according to one embodiment. DETAILED DESCRIPTION

[0029] As will be appreciated by those skilled in the art, certain aspects of the embodiments may be embodied as systems, devices, methods, or program products. Thus, the embodiments may take the form of a complete hardware embodiment, a complete software embodiment (including firmware, resident software, microcode, etc.), or a combination of software and hardware aspects, which may be generally referred to herein as a "circuit," "module," or "system." In addition, the embodiments may take the form of a program product embodied in one or more computer-readable storage devices storing machine-readable code, computer-readable code, and / or program code (hereinafter referred to as "code"). The storage device may be tangible, non-temporary, and / or non-transmitting. The storage device may not embody a signal. In a certain embodiment, the storage device employs only a signal for accessing the code.

[0030] Certain functional units described in this specification may be labeled as "modules" to more particularly emphasize their independent implementation. For example, a module may be implemented as a hardware circuit including custom very large scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors or other discrete components. A module may also be implemented with programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc.

[0031] Module can also be realized with code and / or software for being operated by various types of processors. The identification module of code can for example comprise one or more physical or logical blocks of executable code, and this executable code can for example be organized as object, process or function. However, the executable file of identification module does not need to be physically located together, but can comprise the fundamentally different instructions stored in different positions, and described instruction comprises module and realizes the stated purpose of module when being logically joined together.

[0032] In fact, the module of code can contain a single instruction or many instructions, and can even be distributed on several different code segments, among different programs and across several memory devices. Similarly, operating data can be identified and illustrated in this article in the module, and can be embodied and organized in the data structure of any suitable type in any suitable form. This operating data can be collected as a single data set, or can be distributed on different locations, including being distributed on different computer-readable storage devices. When the modules or parts of the modules are implemented with software, the software part is stored on one or more computer-readable storage devices.

[0033] Any combination of one or more computer readable media may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing code. The storage device may be, for example but need not be, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical or semiconductor system, apparatus or device, or any suitable combination of the foregoing.

[0034] A non-exhaustive list of more specific examples of storage devices would include the following: an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0035] The code for performing the operations of the embodiments may include any number of lines and may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Python, Ruby, Java, Smalltalk, C++, and the like, as well as conventional procedural programming languages ​​such as the "C" programming language and / or machine languages ​​such as assembly languages. The code may run entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the last scenario, the remote computer may be connected to the user's computer through any type of network including a local area network (LAN) or a wide area network (WAN), or a connection may be made to an external computer (e.g., over the Internet using an Internet service provider).

[0036] References throughout this specification to "one embodiment", "embodiment" or similar language mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment. Therefore, unless otherwise expressly specified, the phrases "in one embodiment", "in an embodiment" and similar language throughout this specification may, but not necessarily, refer to the same embodiment, but mean "one or more but not all embodiments". Unless otherwise expressly specified, the terms "include", "comprising", "having" and their variations mean "including but not limited to". Unless otherwise expressly specified, an enumerated list of items does not imply that any or all items are mutually exclusive. Unless otherwise expressly specified, the terms "one", "an" and "the" also refer to "one or more".

[0037] In addition, the features, structures or characteristics of the descriptions of the various embodiments may be combined in any suitable manner. In the following description, many specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of the embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific details or using other methods, components, materials, etc. In other instances, known structures, materials, or operations are not shown or described in detail to avoid any ambiguity in various aspects of the embodiments.

[0038] Aspects of different embodiments are described below with reference to schematic flow charts and / or schematic block diagrams of methods, devices, systems, and program products according to embodiments. It will be understood that each frame of the schematic flow chart and / or schematic block diagram and the combination of frames in the schematic flow chart and / or schematic block diagram can be implemented by code. This code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to generate a machine, so that instructions executed by the processor of the computer or other programmable data processing device create means for implementing the functions specified in the schematic flow chart and / or schematic block diagram of one or more frames.

[0039] The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other device to function in a specific manner so that the instructions stored in the storage device produce an article of manufacture that includes instructions for implementing the functions specified in one or more schematic flowcharts and / or schematic block diagrams.

[0040] The code may also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operational steps are performed on the computer, other programmable apparatus, or other device to produce a computer-implemented process, so that the code running on the computer or other programmable apparatus provides a process for implementing the functions specified in the flowchart and / or one or more block diagram blocks.

[0041] The schematic flow charts and / or schematic block diagrams in the figures illustrate the architecture, functions and operations of possible implementations of the devices, systems, methods and program products according to various embodiments. In this regard, each box in the schematic flow charts and / or schematic block diagrams may represent a module, segment or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function.

[0042] It should also be noted that in some alternative implementations, the functions indicated in the blocks may not occur in the order annotated in the figure. For example, depending on the functionality involved, two blocks shown in succession may be executed substantially concurrently, or the blocks may sometimes be executed in reverse order. For the illustrated figure, other steps and methods that are equivalent in function, logic or effect to one or more blocks or portions thereof may be envisioned.

[0043] Although various arrow types and line types can be used in flow charts and / or block diagrams, they are understood to not limit the scope of the corresponding embodiments. In fact, some arrows or other connectors can be used to indicate only the logical flow of the depicted embodiments. For example, an arrow can indicate a waiting or monitoring period of unspecified duration between the enumeration steps of the depicted embodiments. It should also be noted that each frame of the block diagram and / or flow chart and the combination of frames in the block diagram and / or flow chart can be realized by a combination of a dedicated hardware-based system or dedicated hardware and code that performs a specified function or behavior.

[0044] The description of an element in each figure may refer to an element in a previous figure. Like reference numerals refer to like elements in all figures, including alternative embodiments of like elements.

[0045] First, a brief introduction to the status of TCI is provided as follows:

[0046] The UE can be configured with a list of up to M TCI-State configurations to decode the PDSCH from the detected PDCCH with DCI intended for the UE and a given serving cell, where M depends on the UE capabilities. The TCI-state is configured via the following RRC signaling:

[0047] IE TCI-State associates one or two DL reference signals with the corresponding Quasi Co-location (QCL) type.

[0048] TCI-State Information Element

[0049]

[0050] Each TCI-State contains parameters for configuring the quasi co-location (QCL) relationship between one or two downlink reference signals and the DM-RS ports of the PDSCH, the DM-RS ports of the PDCCH, or the CSI-RS ports of the CSI-RS resources. The quasi co-location relationship is configured by the higher layer parameter qcl-Type1 for the first DL RS, and by the higher layer parameter qcl-Type2 for the second DL RS (if configured). For the case of two DL RSs, the QCL type should not be the same regardless of whether the reference is to the same DL RS or different DL RSs. The quasi co-location type corresponding to each DL RS is given by the higher layer parameter qcl-Type in QCL-Info and can take one of the following values:

[0051] 'QCL-TypeA': {Doppler shift, Doppler spread, average delay, delay spread};

[0052] 'QCL-TypeB': {Doppler shift, Doppler spread};

[0053] 'QCL-TypeC': {Doppler shift, average delay}; and

[0054] 'QCL-TypeD': {spatial Rx parameters}.

[0055] The UE receives an activation command for mapping up to 8 TCI states to codepoints of the DCI field "Transmission Configuration Indication" in one DL BWP of the serving cell.

[0056] In NR Release 17, commands for serving cell changes, such as handover commands, are indicated by RRC signaling, which results in greater handover latency. Handover means that the UE should change its serving cell from the source cell to the target cell. When the handover is successful, the target cell will be used as the new serving cell for subsequent transmission and reception.

[0057] In order to reduce the switching delay, the present disclosure proposes to perform serving cell change in L1 and L2, for example, based on DCI and / or MAC CE.

[0058] The first embodiment relates to the indication of a serving cell change.

[0059] When a UE is configured with a unified TCI framework, one or more (e.g., up to 128) TCI states can be configured to the UE through RRC signaling in the serving cell. Each configured TCI state can be associated with a PCI (physical cell identity), for example, by being associated with an SSB associated with the PCI. The PCI identifies the cell. Each cell has a PCI that is distinct from any other cell. The PCI associated with each configured TCI state can be the same as or different from the PCI of the serving cell.

[0060] In the following description, “TCI state associated with SSB associated with PCI” is abbreviated as “TCI state associated with PCI”.

[0061] Each configured TCI state can be associated with a PCI identifying a serving cell, or with any of the other PCIs that each identify another cell different from the serving cell. Each of the other cells identified by the other PCIs can be considered as a candidate target cell, i.e., a candidate for a target cell for a serving cell change based on L1 and L2 mobility. Thus, the PCI identifying a candidate target cell can be referred to as a candidate target PCI, and the PCI identifying a serving cell is referred to as a serving PCI.

[0062] A first sub-embodiment of the first embodiment involves indicating both the target cell and the serving cell change command in the DCI.

[0063] When two or more (e.g., 2 to 8) configured TCI states are activated for a UE by a MAC CE (e.g., a unified TCI state activation MAC CE) for a BWP for a serving cell, one of the activated TCI states is indicated by a DCI (e.g., a DCI having a format of 1_1 or 1_2) as a unified TCI state for the UE in the BWP. The PCI associated with the indicated unified TCI state may be a serving PCI or a target PCI that is one of the candidate target PCIs.

[0064] If the PCI associated with the indicated unified TCI state is a target PCI (which identifies a target cell), the serving cell change command triggers a change of the serving cell to the target cell identified by the target PCI. In other words, the target cell will be applied as a new serving cell.

[0065] The serving cell change command can be indicated in the DCI by two alternative options.

[0066] Option 1: A new DCI field can be configured in DCI format 1_1 or 1_2 to include a serving cell change command. Option 1 applies when a unified TCI state is indicated by DCI format 1_1 or 1_2 with or without DL assignment. DCI format 1_1 or 1_2 without DL assignment means that the DCI is dedicated to unified TCI state indication without scheduling PDSCH transmission. Details about DCI format 1_1 and DCI format 1_2 are specified in 3GPP technical specification TS38.212 V17.3.0.

[0067] Option 2: The reserved DCI field in DCI format 1_1 or 1_2 can be used to include a serving cell change command. Option 2 is applicable only when a unified TCI state is indicated by DCI format 1_1 or 1_2 without DL assignment.

[0068] Only when the TCI field included in DCI format 1_1 or 1_2 indicates a unified TCI state associated with the target PCI (e.g., associated with an SSB associated with a target PCI different from the PCI of the serving cell), the UE checks the serving cell change command, i.e., checks the new DCI field or the reserved DCI field including the serving cell change command. The serving cell change command can be one bit included in the new DCI field (in option 1) or the reserved DCI field (in option 2). This means that the UE checks the new DCI field or the reserved DCI field by decoding the new DCI field (in option 1) or the reserved DCI field (in option 2). For example, a value of "1" of the DCI field (in option 1) or the reserved DCI field (in option 2) indicates a serving cell change command, i.e., indicates that the serving cell should become (or switch to) a target cell identified by the target PCI associated with the indicated unified TCI state. On the other hand, a value of "0" indicates that the serving cell has not become (or switched to) a target cell identified by the target PCI associated with the indicated unified TCI state. The value '0' of the new DCI field (in option 1) or the reserved DCI field (in option 2) can be referred to as a serving cell unchanged command.

[0069] Otherwise (i.e., if the TCI field included in DCI format 1_1 or 1_2 indicates a TCI state associated with a serving PCI identifying a serving cell (e.g., associated with an SSB associated with the serving PCI), the UE ignores (e.g., by not decoding) the new DCI field (in option 1) or the retained DCI field (in option 2).

[0070] A second sub-embodiment of the first embodiment involves indicating both the target cell and the serving cell change command in the MAC CE.

[0071] For UEs that only support one TCI state activated by MAC CE for BWP of a cell, the unified TCI state is activated (i.e., indicated) by MAC CE. Under this condition, the serving cell change command is indicated by a MAC CE (e.g., unified TCI state activation / deactivation MAC CE) that activates one unified TCI state. For example, a MAC CE field (e.g., a serving cell change / unchanged command field) can be included in the MAC CE to indicate whether the UE should become (or switch to) a target cell identified by a target PCI associated with one unified TCI state activated (and indicated) by MAC CE. The serving cell change / unchanged command field is only valid when the activated unified TCI state is associated with a target PCI different from the PCI of the serving cell. Similar to the first sub-embodiment, a value of "1" of the serving cell change / unchanged command field can indicate a serving cell change command, while a value of "0" of the serving cell change / unchanged command field can indicate a serving cell unchanged command. Otherwise (i.e., when an activated unified TCI state is associated with a serving PCI identifying a serving cell), the UE should ignore (e.g., by not decoding) the serving cell change / unchanged command field.

[0072] A third sub-embodiment of the first embodiment relates to indicating a target cell in a DCI for FR1 operation without configuring a unified TCI framework.

[0073] For FR1 operation without a uniformly configured TCI framework, one or more candidate target cells can be configured for the UE (e.g., via RRC signaling) to enable L1 and L2 based mobility. For example, each candidate target cell is indicated to the UE (e.g., configured via RRC signaling) by a candidate target cell index (e.g., candidate target PCI) that identifies the candidate target cell. Each candidate cell is configured with a PCI that is different from the PCI of the serving cell.

[0074] The target cell index, as one of the candidate target cell indexes configured to the UE, indicates that the target cell can be directly indicated by DCI, which can be a dedicated DCI format or DCI format 1_1 or 1_2 scrambled by a dedicated RNTI. A dedicated field or a reserved field in the DCI can directly indicate the target cell index from the candidate target cell index to identify the target cell.

[0075] In the third sub-embodiment of the first embodiment, the direct indication of the target cell index by the DCI is equivalent to the serving cell change command. This means that after the UE receives the DCI directly indicating the target cell index, the UE assumes that it has received the serving cell change command and should become (or switch to) the target cell identified by the target cell index.

[0076] The second embodiment involves applying a serving cell change, ie, when a target cell is applied as a new serving cell.

[0077] The first embodiment describes two alternative indications of serving cell change, namely, through DCI (eg, in the first and third sub-embodiments of the first embodiment) or through MAC CE (eg, in the second sub-embodiment of the first embodiment).

[0078] The first sub-embodiment of the second embodiment involves applying the serving cell change indicated by DCI.

[0079] When a serving cell change is indicated in a DCI, the serving cell change will be effective (ie, the target cell will be applied) after the UE acknowledges the DCI.

[0080] When the serving cell change command is indicated by DCI format 1_1 or 1_2 (referred to as first DCI) with PDSCH scheduling, HARQ-ACK corresponding to the scheduled PDSCH is regarded as HARQ-ACK information for the first DCI.

[0081] When the serving cell change command is indicated by DCI format 1_1 or 1_2 or another dedicated DCI (collectively referred to as a second DCI) without DL assignment, the UE should report HARQ-ACK information for the second DCI in the codebook indicated by the second DCI.

[0082] This means that the UE needs additional time to perform the serving cell change (e.g., to a target cell). Specifically, the UE sends a PUCCH or PUSCH carrying HARQ-ACK information (e.g., ACK) for the DCI indicating the serving cell change command and the target cell (which is different from the serving cell). The indicated target cell should be applied as the new serving cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH, where x is equal to the ServingCellChangeCommandAppTime reported by the UE capability report per SCS.

[0083] exist Figure 1An example of a first sub-embodiment of the second embodiment is illustrated. The UE receives a DCI indicating a serving cell change command and a target cell identified by a target PCI associated with a unified TCI state indicated in the DCI in slot n. The UE reports HARQ-ACK information (e.g., ACK) for the DCI in slot n+2 in a PUSCH or PUCCH. The target cell is applied starting from slot n+5, i.e., ServingCellChangeCommandAppTime symbols after the last symbol of the PUSCH or PUCCH or the first slot carrying HARQ-ACK information. This means that, starting from slot n+5, the target cell is considered as a serving cell (i.e., a new serving cell). Starting from slot n+5 (i.e., starting from ServingCellChangeCommandAppTime symbols after the last symbol of the PUSCH or PUCCH or the first slot carrying HARQ-ACK information), all PDCCHs and PDSCHs shall be sent by the gNB and received by the UE with the indicated unified TCI state. Additionally, starting from time slot n+5, all PUCCH and PUSCH shall be transmitted by the UE and received by the gNB with the indicated unified TCI state.

[0084] The second sub-embodiment of the second embodiment involves applying the serving cell change indicated by MAC CE.

[0085] Similar to the first sub-embodiment, when the serving cell change is indicated in the MAC CE, the serving cell change will be applied after the UE responds to the MAC CE.

[0086] MAC CE is carried by PDSCH from gNB to UE. After receiving PDSCH carrying MAC CE indicating serving cell change, UE sends PUCCH or PUSCH carrying HARQ-ACK information corresponding to PDSCH carrying MAC CE. Therefore, HARQ-ACK information corresponding to PDSCH can be regarded as HARQ-ACK information for MAC CE. Starting from the first time slot at least 3ms after the last symbol of PUCCH and PUSCH carrying HARQ-ACK information, the target cell indicated in MAC CE shall be applied as the new serving cell. After applying the target cell, all PDCCH and PDSCH shall be sent by gNB and received by UE with one unified TCI state activated by MAC CE, and all PUCCH and PUSCH shall be sent by UE and received by gNB with one unified TCI state activated by MAC CE.

[0087] The third embodiment relates to cell level beam reporting in L1 (Layer 1).

[0088] SSB resources can be associated with PCI. CSI-RS resources associated with PCI mean CSI-RS resources with respect to QCL-TypeA and QCL-TypeD and SSB resources QCL associated with PCI.

[0089] The SSB resources or CSI-RS resources associated with the PCI (including the serving PCI identifying the serving cell and the candidate target PCI identifying the candidate target cell) can be configured as the channel measurement resources (CMR) of the CSI report configuration for cell-level beam reporting. After receiving the CSI report configuration, the UE shall report a beam report, which includes, in addition to the L (L can be 1 or more) beams (where each beam is identified by an SSBRI or CRI) associated with different L PCIs (which means that each of the L beams is associated with a different PCI) and their measured L1-RSRP, the average L1-RSRP of the first K beams associated with each of the L PCIs, where the average L1-RSRP of the first K beams associated with each of the L PCIs is greater than a threshold. For example, determine the L PCIs associated with the maximum L average L1-RSRPs of the first K beams. The value of L, the value of K, and the threshold can be configured through RRC signaling.

[0090] For example, in the case where the CMR contains 32 CSI-RS resources (where each of the CSI-RS resources represents a beam), the UE is configured with a CSI reporting configuration where

[0091] CSI-RS #0, CSI-RS #1, ..., CSI-RS #7 are associated with PCI #0;

[0092] CSI-RS #8, CSI-RS #9, ..., CSI-RS #15 are associated with PCI #1;

[0093] CSI-RS #16, CSI-RS #17, ..., CSI-RS #23 are associated with PCI #2; and

[0094] CSI-RS#24, CSI-RS#25, ..., CSI-RS#31 are associated with PCI #3.

[0095] In addition, the UE is configured to report 2 (i.e., L = 2) beams in the beam report, under the criterion that the average L1-RSRP of the first 4 (i.e., K = 4) beams associated with each of L = 2 different PCIs (among PCI #0, PCI #1, PCI #2 and PCI #3) should be greater than Threshold #1 (i.e., the threshold is Threshold #1).

[0096] The UE shall measure the L1-RSRP of all 32 beams (i.e., CSI-RS#0 to CSI-RS#31) in the CMR and calculate the average L1-RSRP of the first 4 beams associated with each PCI (i.e., each of PCI #0, PCI #1, PCI #2, and PCI #3), where the first 4 beams are the 4 beams with the 4 largest L1-RSRPs measured among all beams associated with each PCI. Among the 4 average L1-RSRPs each associated with a separate PCI, select two PCIs associated with the largest two average L1-RSRPs each of which is greater than Threshold#1. By the way, if only one average L1-RSRP among the four average L1-RSRPs is greater than Threshold#1, only one PCI associated with the one average L1-RSRP is selected, and if none of the four average L1-RSRPs is greater than Threshold#1, no PCI is selected. It is assumed that two PCIs are selected.

[0097] For each of the two selected PCIs, a beam having a maximum L1-RSRP associated with the selected PCI is selected. Between the two selected beams, the larger one is denoted as CRI #1 and the smaller one is denoted as CRI #2, where CRI is a CSI-RS resource indicator. The L1-RSRP of CRI #1 is denoted as RSRP #1 and the L1-RSRP of CRI #2 is denoted as RSRP #2.

[0098] The average L1-RSRP of the first 4 beams associated with the PCI associated with the CSI-RS resource indicated by CRI #1 is represented as average RSRP #1. The average L1-RSRP of the first 4 beams associated with the PCI associated with the CSI-RS resource indicated by CRI #2 is represented as average RSRP #2.

[0099] Obviously, among RSRP #1, RSRP #2, average RSRP #1, and average RSRP #2, RSRP #1 is the maximum value. Therefore, differential average RSRP #1, differential RSRP #2, and differential average RSRP #2 are calculated with reference to the measured maximum RSRP (i.e., RSRP #1), i.e., differential average RSRP #1 = RSRP #1 - average RSRP #1; differential RSRP #2 = RSRP #1 - RSRP #2; and differential average RSRP #2 = RSRP #1 - average RSRP #2.

[0100] The beam report includes the format of {CRI#1, CRI#2, RSRP#1, differential average RSRP#1, differential RSRP#2, differential average RSRP#2}.

[0101] The fourth embodiment relates to TA (Timing Advance) for L1 and L2 signaling triggered mobility.

[0102] In NR Release 17, each serving cell is configured with a TAG (TA Group) for the UE to obtain a TA for UL transmission in the serving cell (e.g., one TRP to the serving cell). When the UE moves from the coverage of the serving cell to another cell (e.g., a target cell), the TRP for UL transmission is changed (e.g., becomes a TRP of the target cell), which may result in a different TA (e.g., a new TA). Therefore, a new TA for the target cell may be required. In NR Release 17 handover (i.e., serving cell change), the new TAG configured for the target cell can be indicated through the L3 handover message.

[0103] According to the fourth embodiment, if a serving cell change (e.g., becoming a target cell) is applied, the TAG configured for the target cell should be indicated to the UE. Each TAG can be identified by a TAG ID. This means that it is necessary to indicate to the UE the TAG ID associated with the target cell (i.e., configured for the target cell).

[0104] According to the first sub-embodiment of the fourth embodiment, when a serving cell and one or more candidate target cells are configured for a UE through RRC signaling for L1 and L2 triggered mobility, each cell can be associated with a TAG ID. For example, when a unified TCI framework is configured for a UE in a cell and one or more TCI states configured in the cell are associated with a PCI (e.g., a serving PCI, or one of the candidate target PCIs) through RRC signaling, each PCI in the PCI can be associated with a TAG ID.

[0105] When the target PCI is indicated (for example, the unified TCI state associated with the target PCI is indicated, as in the first sub-embodiment of the first embodiment or in the second sub-embodiment of the first embodiment; or the target PCI is directly indicated, as in the third sub-embodiment of the first embodiment), the serving cell is changed to the target cell identified by the target PCI, and the TA obtained according to the TAG identified by the TAG ID associated with the target PCI is determined as the new TA. When the target cell is applied, for example, starting from the first time slot of at least ServingCellChangeCommandAppTime symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI indicating the serving cell change command and the unified TCI state associated with the target PCI, the new TA is applied.

[0106] According to the second sub-embodiment of the fourth embodiment, each unified TCI state is associated with a TAG ID.

[0107] For example, each TCI state in the unified TCI state configured by RRC signaling can be associated with a TAG ID. For another example, each of the TCI states activated by MAC CE (e.g., unified TCI state activation / deactivation MAC CE) can be associated with a TAG ID by MAC CE. By the way, all TCI states associated with the same PCI should be associated with the same TAG ID.

[0108] According to the third sub-embodiment of the fourth embodiment, one or more TAG IDs are directly indicated by a DCI or MAC CE indicating a serving cell change command.

[0109] For example, a "TAG ID" field can be introduced in a DCI or MAC CE for indicating a serving cell change command. When a target cell is indicated together with a serving cell change command, the UE should further decode the "TAG ID" field to obtain the TAG for the target cell (which is the new serving cell).

[0110] Figure 2 2 is a schematic flow chart illustrating an embodiment of a method 200 according to the present application. In some embodiments, the method 200 is performed by a device such as a remote unit (e.g., a UE). In some embodiments, the method 200 may be performed by a processor that executes program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0111] Method 200 is a method performed at a UE, including: 202 receiving a DCI or MAC CE indicating a serving cell change command for a target cell; and 204 applying the target cell as a new serving cell after sending HARQ-ACK information for the DCI or MAC CE.

[0112] In some embodiments, the DCI indicates a unified TCI state from two or more TCI states that are activated, wherein the unified TCI state is associated with an SSB associated with a physical cell ID that identifies one of the candidate target cells, and the serving cell change command indicates to apply the target cell that is one of the candidate target cells. For example, the DCI is a DCI with format 1_1 or 1_2 including a new field indicating a serving cell change command, or a DCI with format 1_1 or 1_2 without DL assignment including a reserved field indicating a serving cell change command.

[0113] In some embodiments, the MAC CE activates a unified TCI state, wherein the unified TCI state is associated with the SSB associated with the physical cell ID identifying one of the candidate target cells, and the serving cell change command indicates to apply the target cell as one of the candidate target cells.

[0114] In some embodiments, the DCI indicates a physical cell ID of one of the candidate target cells as a serving cell change command, and the serving cell change command indicates to apply the target cell as one of the candidate target cells. For example, the DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

[0115] In some embodiments, the method includes applying the target cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0116] In some embodiments, the method further includes receiving all PDCCHs and PDSCHs with a unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0117] In some embodiments, the method further includes receiving a CSI report configuration; and sending a beam report including one or more beam indices with the measured L1-RSRP, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cell is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, and for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

[0118] In some embodiments, the DCI or MAC CE further indicates a TAG ID. Alternatively, a unified TCI state or a physical cell ID identifying a target cell is associated with the TAG ID.

[0119] Figure 3 300 is a schematic flow chart illustrating an embodiment of a method 300 according to the present application. In some embodiments, the method 300 is performed by a device such as a base station unit. In some embodiments, the method 300 can be performed by a processor that executes program code, for example, by a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0120] The method 300 may include 302 transmitting a DCI or MAC CE indicating a serving cell change command for a target cell; and 304 applying the target cell as a new serving cell after receiving HARQ-ACK information for the DCI or MAC CE.

[0121] In some embodiments, the DCI indicates a unified TCI state from two or more TCI states that are activated, wherein the unified TCI state is associated with an SSB associated with a physical cell ID that identifies one of the candidate target cells, and the serving cell change command indicates to apply the target cell that is one of the candidate target cells. For example, the DCI is a DCI with format 1_1 or 1_2 including a new field indicating a serving cell change command, or a DCI with format 1_1 or 1_2 without DL assignment including a reserved field indicating a serving cell change command.

[0122] In some embodiments, the MAC CE activates a unified TCI state, wherein the unified TCI state is associated with the SSB associated with the physical cell ID identifying one of the candidate target cells, and the serving cell change command indicates to apply the target cell as one of the candidate target cells.

[0123] In some embodiments, the DCI indicates a physical cell ID of one of the candidate target cells as a serving cell change command, and the serving cell change command indicates to apply the target cell as one of the candidate target cells. For example, the DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

[0124] In some embodiments, the method includes applying the target cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0125] In some embodiments, the method further includes sending all PDCCHs and PDSCHs with a unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0126] In some embodiments, the method further includes sending a CSI report configuration; and receiving a beam report including one or more beam indices with the measured L1-RSRP, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cell is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, and for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

[0127] In some embodiments, the DCI or MAC CE further indicates a TAG ID. Alternatively, a unified TCI state or a physical cell ID identifying a target cell is associated with the TAG ID.

[0128] Figure 4 is a schematic block diagram illustrating an apparatus according to one embodiment.

[0129] refer to Figure 4 , the UE (ie, remote unit) includes a processor, a memory, and a transceiver. The processor implements Figure 2 The functions, processes and / or methods proposed in.

[0130] The UE includes a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to receive a DCI or MAC CE indicating a serving cell change command for a target cell via the transceiver; and apply the target cell as a new serving cell after sending HARQ-ACK information for the DCI or MAC CE via the transceiver.

[0131] In some embodiments, the DCI indicates a unified TCI state from two or more TCI states that are activated, wherein the unified TCI state is associated with an SSB associated with a physical cell ID that identifies one of the candidate target cells, and the serving cell change command indicates to apply the target cell that is one of the candidate target cells. For example, the DCI is a DCI with format 1_1 or 1_2 including a new field indicating a serving cell change command, or a DCI with format 1_1 or 1_2 without DL assignment including a reserved field indicating a serving cell change command.

[0132] In some embodiments, the MAC CE activates a unified TCI state, wherein the unified TCI state is associated with the SSB associated with the physical cell ID identifying one of the candidate target cells, and the serving cell change command indicates to apply the target cell as one of the candidate target cells.

[0133] In some embodiments, the DCI indicates a physical cell ID of one of the candidate target cells as a serving cell change command, and the serving cell change command indicates to apply the target cell as one of the candidate target cells. For example, the DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

[0134] In some embodiments, the processor is configured to apply the target cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via the UE capability report per SCS.

[0135] In some embodiments, the processor is further configured to receive all PDCCHs and PDSCHs with a unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0136] In some embodiments, the processor is further configured to receive a CSI report configuration via the transceiver; and send a beam report via the transceiver including one or more beam indices with the measured L1-RSRP, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cell is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

[0137] In some embodiments, the DCI or MAC CE further indicates a TAG ID. Alternatively, a unified TCI state or a physical cell ID identifying a target cell is associated with the TAG ID.

[0138] The gNB (i.e., base station unit) includes a processor, memory, and a transceiver. The processor implements Figure 3 The functions, processes and / or methods proposed in.

[0139] The base station unit includes a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to send a DCI or MAC CE indicating a serving cell change command for a target cell via the transceiver; and apply the target cell as a new serving cell after receiving HARQ-ACK information for the DCI or MAC CE via the transceiver.

[0140] In some embodiments, the DCI indicates a unified TCI state from two or more TCI states that are activated, wherein the unified TCI state is associated with an SSB associated with a physical cell ID that identifies one of the candidate target cells, and the serving cell change command indicates to apply the target cell that is one of the candidate target cells. For example, the DCI is a DCI with format 1_1 or 1_2 including a new field indicating a serving cell change command, or a DCI with format 1_1 or 1_2 without DL assignment including a reserved field indicating a serving cell change command.

[0141] In some embodiments, the MAC CE activates a unified TCI state, wherein the unified TCI state is associated with the SSB associated with the physical cell ID identifying one of the candidate target cells, and the serving cell change command indicates to apply the target cell as one of the candidate target cells.

[0142] In some embodiments, the DCI indicates a physical cell ID of one of the candidate target cells as a serving cell change command, and the serving cell change command indicates to apply the target cell as one of the candidate target cells. For example, the DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

[0143] In some embodiments, the processor is configured to apply the target cell starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via the UE capability report per SCS.

[0144] In some embodiments, the processor is further configured to send all PDCCHs and PDSCHs with a unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

[0145] In some embodiments, the processor is further configured to send a CSI report configuration via the transceiver; and receive a beam report via the transceiver including one or more beam indices with measured L1-RSRP, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cell is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

[0146] In some embodiments, the DCI or MAC CE further indicates a TAG ID. Alternatively, a unified TCI state or a physical cell ID identifying a target cell is associated with the TAG ID.

[0147] The layers of the radio interface protocol may be implemented by a processor. The memory is connected to the processor to store various pieces of information for driving the processor. The transceiver is connected to the processor to send and / or receive radio signals. Needless to say, the transceiver may be implemented as a transmitter that sends radio signals and a receiver that receives radio signals.

[0148] The memory may be located inside or outside the processor and connected to the processor through various well-known means.

[0149] In the above-described embodiments, the components and features of the embodiments are combined in a predetermined form. Unless otherwise explicitly stated, each component or feature should be considered as an option. Each component or feature can be implemented as not associated with other components or features. In addition, the embodiments can be configured by associating some components and / or features. The order of the operations described in the embodiments can be changed. Some components or features of any embodiment can be included in another embodiment or replaced with components and features corresponding to another embodiment. It is obvious that claims that are not explicitly recorded in the claims are combined to form embodiments or are included in new claims.

[0150] The embodiments may be implemented by hardware, firmware, software or a combination thereof. In the case of being implemented by hardware, the exemplary embodiments described herein may be implemented by using one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc., according to the hardware implementation.

[0151] Embodiments may be practiced in other specific forms. The described embodiments will be considered in all respects to be illustrative only and not restrictive. Therefore, the scope of the present invention is indicated in the appended claims rather than by the above description. All changes that fall within the meaning and range of equivalents of the claims will be included within their scope.

Claims

1. A user equipment (UE), comprising: Transceiver; as well as a processor coupled to the transceiver, wherein the processor is configured to receiving, via the transceiver, a DCI or a MAC CE indicating a serving cell change command for a target cell; and The target cell is applied as a new serving cell after sending HARQ-ACK information for the DCI or the MAC CE via the transceiver.

2. The UE according to claim 1, wherein: The DCI indicates a unified TCI state from among two or more activated TCI states, wherein the unified TCI state is associated with an SSB associated with a physical cell ID identifying one of the candidate target cells, and The serving cell change command indicates to apply the target cell as the one of the candidate target cells.

3. The UE according to claim 2, wherein The DCI is a DCI having format 1_1 or 1_2 including a new field indicating the serving cell change command, or a DCI having format 1_1 or 1_2 without DL assignment including a reserved field indicating the serving cell change command.

4. The UE according to claim 1, wherein: The MAC CE activates a unified TCI state, wherein the unified TCI state is associated with an SSB associated with a physical cell ID identifying one of the candidate target cells, and The serving cell change command indicates to apply the target cell as the one of the candidate target cells.

5. The UE according to claim 1, wherein: The DCI indication indicates a physical cell ID of one of the candidate target cells as the serving cell change command, and The serving cell change command indicates to apply the target cell as the one of the candidate target cells.

6. The UE according to claim 5, wherein: The DCI is a dedicated DCI format or a DCI format 1_1 or 1_2 scrambled by a dedicated RNTI.

7. The UE according to claim 1, wherein: The processor is configured to apply the target cell starting from a first time slot at least x symbols after a last symbol of a PUCCH or PUSCH carrying the HARQ-ACK information for the DCI, where x is reported via a UE capability report per SCS.

8. The UE according to claim 2, wherein: The processor is further configured to receive all PDCCHs and PDSCHs through the unified TCI state starting from the first time slot at least x symbols after the last symbol of the PUCCH or PUSCH carrying the HARQ-ACK information for the DCI, where x is reported through the UE capability report per SCS.

9. The UE according to claim 1, wherein: The processor is further configured to receiving, via the transceiver, a CSI reporting configuration; and A beam report including one or more beam indices with measured L1-RSRP is sent via the transceiver, wherein each of the one or more beam indices identifies a beam from a different cell, and the average L1-RSRP of the first K beams of the different cells is greater than a configured threshold, wherein the beam report also includes the average L1-RSRP of the first K beams of each cell, and for each cell, the beam index of the beam is included in the beam report, wherein K is a preconfigured value.

10. The UE according to claim 1, wherein: The DCI or the MAC CE further indicates a TAG ID.

11. The UE according to claim 2, wherein: The unified TCI state or the physical cell ID identifying the target cell is associated with a TAG ID.

12. The UE according to claim 4, wherein: The unified TCI state or the physical cell ID identifying the target cell is associated with a TAG ID.

13. A method performed at a user equipment (UE), comprising: receiving a DCI or a MAC CE indicating a serving cell change command for a target cell; as well as The target cell is applied as a new serving cell after sending HARQ-ACK information for the DCI or the MAC CE.

14. A base station unit, comprising: Transceiver; as well as a processor coupled to the transceiver, wherein the processor is configured to sending, via the transceiver, a DCI or a MAC CE indicating a serving cell change command for a target cell; and The target cell is applied as a new serving cell after receiving HARQ-ACK information for the DCI or the MAC CE via the transceiver.

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