Enhancement of L1 measurement / reporting and beam switching for target cell with carrier aggregation

Abstract

Embodiments disclose methods for measurement and reporting enhancements for lower layer triggered mobility (LTM) scenarios with carrier aggregation. A user equipment (UE) receives configuration information from a source distributed unit (DU), based on which the UE is configured to perform Layer 1 (L1) measurements of a secondary cell (SCell) among one or more candidate cell groups. Based on the measurement of the SCell, the source DU transmits an LTM handover command to the UE such that the UE switches to the beam of the SCell. The UE receives a Media Access Control (MAC) Control Element (CE) that activates a Transmission Configuration Indicator (TCI) state of the SCell prior to handover to a beam of the SCell.

Description

TECHNICAL FIELD

[0001] Various example embodiments of the present disclosure relate to the field of telecommunications, and more specifically to enhancements for Layer 1 (L1) measurement / reporting and beam switching for target cells with carrier aggregation. BACKGROUND

[0002] Certain acronyms that can be found in the specification and / or drawings are defined herein below.

[0003]

[0004] In a wireless communication network, there can be areas of radio coverage, referred to as “cells”. Each cell can be supported by a network node (e.g., a base station). A user equipment can have a source cell, where the user equipment is associated with a network node (i.e., a source network node) that serves the source cell. When the cell quality of the source cell falls below a threshold as compared to the cell quality of a target cell, the UE can undergo a mobility procedure to the target cell. The ability of a UE to effectively communicate with a wireless communication system as it moves across cells is commonly referred to as mobility. 3GPP (Third Generation Partnership Project) Release 18 (Rel-18) introduced Layer 1 (L1) or Layer 2 (L2) mobility, also referred to as lower layer triggered mobility (LTM), for reducing latency, overhead, and interruption time associated with a UE moving between different cells. In a Rel-18 LTM handover procedure, the UE sends an L1 measurement report of the target cell(s) to its serving cell, and based on the L1 measurement report, the serving cell transmits an LTM handover command to the UE indicating which target cell should be used for cell change.

[0005] Carrier aggregation (CA) is a technique that can combine cells to enable a user equipment to achieve higher data rates. In CA, there can be one or more cell groups, where each cell group includes a primary cell (PCell) (i.e., a cell operating on a primary frequency) and at least one secondary cell (SCell) (i.e., a cell operating on a secondary frequency). Although Rel-18 targets LTM for CA, it is currently limited to (1) L1 measurements of the PCell and (2) beam switch indication for only the PCell. In other words, in Rel-18, L1 measurements of the SCell and beam switch indication for the SCell are not considered. SUMMARY

[0006] According to some aspects, subject matter of the independent claims is provided. Some embodiments are defined in the dependent claims.

[0007] In a first aspect of the disclosure, a method is provided, comprising: receiving, from a source network node serving a user equipment (UE), a higher layer message for a mobility procedure, the higher layer message comprising lower layer triggered mobility (LTM) configuration information, the LTM configuration information comprising an indication to distinguish at least one secondary cell (SCell) in each of one or more candidate cell groups from each other, wherein each candidate cell group comprises a primary cell (PCell) and at least one SCell; performing, based on the configuration information, L1 measurements of the PCell in each of the candidate cell groups; sending, to the source network node, a first measurement report of the L1 measurements of the PCell in each of the candidate cell groups; receiving, from the source network node based on the first measurement report, a medium access control (MAC) control element (CE), the MAC CE being used to activate layer 1 (L1) measurements of at least one SCell of a target cell group among the one or more candidate cell groups; performing, based on the MAC CE and the configuration information, the L1 measurements of the at least one SCell of the target cell group; and sending, to the source network node, a second measurement report of the L1 measurements of the at least one SCell.

[0008] In a second aspect of the disclosure, a method is provided, comprising: receiving, from a source network node serving a user equipment, a higher layer message for a mobility procedure, the higher layer message comprising: lower layer triggered mobility (LTM) configuration information of one or more candidate cell groups, wherein each candidate cell group comprises a primary cell (PCell) and at least one secondary cell (SCell); and selection criteria for measurements of at least one SCell associated with the PCell in each of the candidate cell groups; performing, based on the configuration information, L1 measurements of the PCell in each of the candidate cell groups; sending, to the source network node, a first measurement report of the L1 measurements of the PCell in each of the candidate cell groups; determining, based on the first measurement report, a subset of PCells, the subset of PCells comprising the PCell in each of the candidate cell groups that satisfies the selection criteria; performing L1 measurements of at least one SCell associated with the subset of PCells; and sending, to the source network node, a second measurement report of the L1 measurements of the at least one SCell associated with the subset of PCells.

[0009] In a third aspect of the disclosure, a method is provided, comprising: receiving, from a source network node serving a user equipment, a higher layer message for a mobility procedure, the higher layer message comprising lower layer triggered mobility (LTM) configuration information of one or more candidate cell groups, wherein each candidate cell group comprises a primary cell (PCell) and at least one secondary cell (SCell); performing, based on the configuration information, L1 measurements of the PCell in each candidate cell group; sending, to the source network node, a first measurement report of the L1 measurements of the PCell in each candidate cell group; determining, based on the first measurement report, that a PCell of a target cell group among the one or more candidate cell groups has a best beam among the PCells in each candidate cell group; performing, based on the configuration information, L1 measurements of at least one SCell of the target cell group; and sending, to the source network node, a second measurement report of the L1 measurements of the at least one SCell of the target cell group.

[0010] In a fourth aspect of the disclosure, a method is provided, comprising: receiving, from a source network node serving a user equipment, a higher layer message for a mobility procedure, the higher layer message comprising lower layer triggered mobility (LTM) configuration information of one or more candidate cell groups, wherein each candidate cell group comprises a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell; performing, based on the configuration information, L1 measurements of the PCell from the one or more candidate cell groups and the at least one SCell associated with the PCell; and sending, to the source network node, a first measurement report of the L1 measurements of the PCell from the one or more candidate cell groups and the at least one SCell associated with the PCell.

[0011] In a fifth aspect of the disclosure, a method is provided, comprising: receiving, from a source network node serving a user equipment, a higher layer message for a mobility procedure, the higher layer message comprising lower layer triggered mobility (LTM) configuration information of one or more candidate cell groups, wherein each candidate cell group comprises a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell; performing, based on the configuration information, L1 measurements of the PCell from each candidate cell group; sending, to the source network node, a first measurement report of the L1 measurements of the PCell from each candidate cell group; performing, based on the configuration information, L1 measurements of the at least one SCell from each candidate cell group; and sending, to the source network node, a second measurement report of the L1 measurements of the at least one SCell from each candidate cell group. The method comprises sending the first measurement report as a MAC CE. In the method, the source network node comprises a flag for a beam indication of the at least one SCell for each candidate cell group when preparing each candidate cell group. The method can comprise: receiving a LTM switch signal comprising a TCI state list, the TCI state list comprising at least one TCI state mapped to the at least one SCell of a target cell group among the one or more candidate cell groups; and applying, based on the mapping in the TCI state list, the TCI state to the at least one SCell of the target cell group. The method can comprise: receiving a MAC CE for activating the TCI state of the at least one SCell of the target cell group, wherein the MAC CE comprises an index of the at least one SCell; and receiving a LTM switch signal, the LTM switch signal comprising the index of the at least one SCell for which the TCI state is activated. The MAC CE comprises: an index of the target cell group; and a bitmap of the at least one SCell.

[0012] In a sixth aspect of this disclosure, a user equipment is provided, comprising: at least one memory; and at least one processor operatively coupled to the at least one memory, wherein the at least one processor is configured to enable the means to: receive from a source network node serving a UE a higher-layer message for a mobility procedure, the higher-layer message including lower-layer triggered mobility (LTM) configuration information, the LTM configuration information including an indication distinguishing at least one secondary cell (SCell) in each of one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one SCell; perform L1 measurements of the PCell in each candidate cell group based on the configuration information; send a first measurement report of the L1 measurements of the PCell in each candidate cell group to the source network node; receive a Media Access Control (MAC) control element (CE) from the source network node based on the first measurement report, the MAC CE being used to activate a Layer 1 (L1) measurement of at least one SCell in a target cell group among one or more candidate cell groups; perform L1 measurements of at least one SCell in the target cell group based on the MAC CE and the configuration information; and send a second measurement report of the L1 measurements of at least one SCell to the source network node.

[0013] In a seventh aspect of this disclosure, a user equipment is provided, comprising: at least one memory; and at least one processor operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the means to: receive, from a source network node serving a UE, a higher-layer message for a mobility procedure, the higher-layer message including: lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell); and selection criteria for measurements of at least one SCell associated with a PCell in each candidate cell group; perform L1 measurements of the PCells in each candidate cell group based on the configuration information; send a first measurement report of the L1 measurements of the PCells in each candidate cell group to the source network node; determine a subset of PCells based on the first measurement report, the subset of PCells including PCells in each candidate cell group that satisfy the selection criteria; perform L1 measurements of at least one SCell associated with the subset of PCells; and send a second measurement report of the L1 measurements of at least one SCell associated with the subset of PCells to the source network node.

[0014] In an eighth aspect of this disclosure, a user equipment is provided, comprising: at least one memory; and at least one processor operatively coupled to the at least one memory, wherein the at least one processor is configured to enable the means to: receive a higher-layer message for a mobility procedure from a source network node serving a UE, the higher-layer message including lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell); perform L1 measurements of the PCells in each candidate cell group based on the configuration information; send a first measurement report of the L1 measurements of the PCells in each candidate cell group to the source network node; determine, based on the first measurement report, that the PCell of a target cell group among the one or more candidate cell groups has the best beam among the PCells in each candidate cell group; perform L1 measurements of at least one SCell of the target cell group based on the configuration information; and send a second measurement report of the L1 measurements of at least one SCell of the target cell group to the source network node.

[0015] In a ninth aspect of this disclosure, a user equipment is provided, comprising: at least one memory; and at least one processor operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the UE to: receive a higher-layer message for a mobility procedure from a source network node serving the UE, the higher-layer message including lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell; perform L1 measurements of the PCell and at least one SCell associated with the PCell from the one or more candidate cell groups based on the configuration information; and send a first measurement report of the L1 measurements of the PCell and at least one SCell associated with the PCell from the one or more candidate cell groups to the source network node.

[0016] In a tenth aspect of this disclosure, a user equipment is provided, comprising: at least one memory; and at least one processor operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the UE to: receive a higher-layer message for a mobility procedure from a source network node serving the user equipment, the higher-layer message including lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell; perform L1 measurements from the PCell of each candidate cell group based on the configuration information; send a first measurement report of the L1 measurements from the PCell of each candidate cell group to the source network node; perform L1 measurements from at least one SCell of each candidate cell group based on the configuration information; and send a second measurement report of the L1 measurements from at least one SCell of each candidate cell group to the source network node. In the method, the UE sends the second measurement report as a MAC CE. In the tenth aspect, the source network node includes a flag when preparing each candidate cell group, the flag being for beam indication of at least one SCell of each candidate cell group. In a tenth aspect, at least one processor in the UE is configured to cause the UE to: receive an LTM handover signal including a TCI state list, the TCI state list including at least one TCI state of at least one SCell of a target cell group mapped to one or more candidate cell groups; and apply the TCI state to at least one SCell of the target cell group based on the mapping in the TCI state list. In a tenth aspect, at least one processor in the UE is configured to cause the UE to: receive a MAC CE for activating the TCI state of at least one SCell of the target cell group, wherein the MAC CE includes an index of at least one SCell; and receive an LTM handover signal including an index of at least one SCell whose TCI state is activated. In a tenth aspect, the MAC CE includes: an index of the target cell group; and a bitmap of at least one SCell. Attached Figure Description

[0017] In the following, various exemplary embodiments will be described in more detail with reference to the accompanying drawings, wherein: Figure 1 shows the message sequence diagram for the Rel-18 LTM procedure for the primary cell; Figure 2A and Figure 2B The LTM carrier aggregation scenario with different operating frequencies for secondary cells is shown; Figure 3 illustrates a message sequence diagram including measurement and reporting enhancements for a target secondary cell according to an example embodiment of the present disclosure; Figure 4 illustrates a message sequence diagram including enhanced Transmission Configuration Indicator (TCI) state handover for a target secondary cell according to an example embodiment of the present disclosure; Figures 5A-5B A method for measurement enhancement of a target secondary cell according to an exemplary embodiment of the present disclosure is shown; Figures 6A-6B A method for measurement enhancement of a target secondary cell according to an exemplary embodiment of the present disclosure is shown; Figures 7A-7B A third aspect of a method for measurement enhancement of a target secondary cell according to an exemplary embodiment of the present disclosure is shown; Figure 8 A fourth aspect of a method for measurement enhancement of a target secondary cell according to an exemplary embodiment of the present disclosure is shown; Figure 9 A fifth aspect of a method for measurement enhancement of a target secondary cell according to an exemplary embodiment of the present disclosure is shown; Figure 10 A method for the preparation phase of TCI state handover enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown; Figure 11 A method for the execution phase of TCI state handover enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown; Figure 12 A method for another execution phase of TCI state enhancement for a target secondary cell according to an example embodiment of this disclosure is shown; and Figure 13 An apparatus suitable for implementing example embodiments of this disclosure is shown. Detailed Implementation

[0018] Example embodiments will now be described in conjunction with the accompanying drawings. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments described herein; rather, these embodiments are provided so that the invention will be thorough and complete, and its scope will be fully conveyed to those skilled in the art. The terminology used in the detailed description of the example embodiments shown in the drawings is not intended to be limiting. In the drawings, the same reference numerals denote the same elements.

[0019] This specification may refer to "an," "a," or "some" embodiments in several places. This does not necessarily mean that every such reference refers to the same embodiment, or that the feature applies only to a single embodiment. Individual features of different embodiments may also be combined to provide other embodiments. As used herein, unless expressly stated otherwise, the singular article is intended to include the plural form as well. It should also be further understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. In other words, the terms "comprising" and / or "including" should be understood as open-ended. As used herein, whenever the phrase "at least one of the following" precedes a list of elements connected by "and" or "or," it means that at least one of the elements or at least all of the elements are present. As used herein, the term "and / or" includes any and all combinations and permutations of one or more of the listed related items.

[0020] Conditional terms—such as “may” or “may”—are generally intended to indicate, unless explicitly stated otherwise or understood differently in the context in which they are used, that certain embodiments may include certain features, elements, and / or steps, while other embodiments may not include certain features, elements, and / or steps. Therefore, such conditional terms are not generally intended to imply that a feature, element, and / or step is necessary in any respect for one or more embodiments. It should be understood that when an element is referred to as “connected” or “coupled” to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element. Furthermore, as used herein, “connected” or “coupled” may also include wireless connections or wireless couplings.

[0021] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms as defined in commonly used dictionaries shall be interpreted as having a meaning consistent with the context of the relevant technical field, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0022] The accompanying drawings illustrate only a simplified structure, showing only some elements and functional entities; all of these are logical units, and their implementation may differ from what is shown. The connections shown are logical connections; actual physical connections may differ. Furthermore, all logical units described and shown in the drawings include the software and / or hardware components required for the unit's operation. Further, each unit may internally include one or more components, as implicitly understood. These components may be operatively coupled to each other and configured to communicate with each other to perform the functions of the unit.

[0023] As used in this application, the term "circuit" may refer to one of the following: (a) Implemented only in hardware circuitry (e.g., in purely analog and / or digital circuitry). (b) A combination of hardware circuitry and software, such as (if applicable): (i) a combination of (multiple) analog and / or digital hardware circuitry and software / firmware, and (ii) any part of a hardware processor having software (including (multiple) digital signal processors, software, and (multiple) memories, which work together to enable a device (such as a mobile phone or server) to perform various functions); or (c) The operation requires software (e.g., firmware) for the operation of (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or parts thereof, but the software may be absent when the operation does not require the software.

[0024] This definition of "circuit" applies to all uses of the term in this application. As a further example, as used in this application, the term "circuit" also covers only hardware circuitry or processors (or processors), or portions of hardware circuitry or servers and their accompanying software and / or firmware implementations. For example, where applicable to certain claim elements, the term "circuit" also covers baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or networking devices.

[0025] Before providing a detailed description of exemplary embodiments of this disclosure, some general principles of wireless communication systems and mobile communication devices will be briefly explained in conjunction with FIG1 to aid in understanding the technology behind the described examples.

[0026] In the following description, different example embodiments will be illustrated using a communication network architecture based on the 3rd Generation Partnership Project (3GPP) standard (e.g., 5G New Radio (5G NR)) as an example of an applicable embodiment, but the embodiments are not limited to this architecture. It will be apparent to those skilled in the art that the embodiments can also be applied to other types of communication networks in which mobile communication principles are combined with device-to-device (D2D) or vehicle-to-everything (V2X) configurations, such as sidelinks (SL), such as Wi-Fi, WiMAX, Bluetooth, personal communication services, ZigBee, Wideband Code Division Multiple Access (WCDMA), systems using ultra-wideband (UWB) technology, mobile ad hoc networks (MANET), wired access, etc. Furthermore, without loss of generality, while the description of some example embodiments relates to mobile communication networks, the principles of this disclosure can be extended and applied to any other type of communication network, such as wired communication networks.

[0027] The basic system architecture of a (electrical)communication network, including a mobile communication system, applicable to certain example embodiments, may include the architecture of one or more communication networks, comprising a radio access network subsystem and a core network. Such an architecture may include one or more communication network control elements or functions, access network elements, radio access network elements, access serving network gateways, or network nodes, such as base stations (BS), access points (APs), NodeBs (NBs), evolved NodeBs (eNBs) or next-generation NodeBs (gNBs), distributed units (DUs), or centralized / centralized units (CUs) that control a corresponding coverage area or cell, and one or more communication stations (e.g., communication elements or functions, such as user equipment or terminal equipment, such as user equipment (UE), or another device with similar functionality, such as a modern chipset, chip, module, etc., which may also be part of a communication-enabled station, element, function, or application, such as a UE, an element or function suitable for a machine-to-machine communication architecture, or attached as a separate element to such a communication-enabled element, function, or application, or the like) capable of transmitting several types of data in multiple access domains via one or more channels and via one or more communication beams. In addition, it may include core network elements or network functions, such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, databases, etc.

[0028] The UE can be any device capable of transmitting and receiving radio signals. Non-limiting examples of the UE include mobile stations (MS) or mobile devices, such as mobile phones or so-called "smartphones," computers equipped with wireless interface cards or other wireless interface facilities (such as Universal Serial Bus dongles), personal digital assistants (PDAs) or tablet devices equipped with wireless communication capabilities, machine-type devices, or any combination of these or similar devices.

[0029] A network node may include a processor and associated circuitry to execute or direct the execution of computer-readable instructions to perform the operations further described herein. In short, a network node may retrieve and execute software from a storage device, which may include a disk drive, flash drive, storage circuitry, or other storage device, and may be locally or remotely accessible. The software may include computer programs, firmware, or other forms of machine-readable instructions, and may include operating systems, utilities, drivers, network interfaces, applications, or other types of software, including combinations thereof. Furthermore, the network node may receive instructions and other input at a user interface.

[0030] The gNB Central Unit (gNB-CU) includes, for example, logical nodes that carry, for example, the Radio Resource Control (RRC), Serving Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB, or the Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) protocols of an enhanced gNB (en-GNB), and control the operation of one or more gNB Distributed Units (gNB-DUs). The gNB-CU terminates the F1 interface connected to the gNB-DU. For simplicity, and because the embodiments disclosed herein are applicable to evolution systems beyond 5G New Radio (5G NR) systems, the gNB-CU may be referred to as a CU.

[0031] A gNB Distributed Unit (gNB-DU) includes, for example, a logical node that carries, for example, the radio link control (RLC), media access control (MAC), and physical layer (PHY) layers of a gNB or en-gNB, and its operation is controlled by a gNB-CU. A gNB-DU supports one or more cells. A cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU. A gNB-DU can support one or more cells and therefore can, for example, serve as the UE's serving cell. The gNB-CU and gNB-DU portions can, for example, be co-located or physically separated. For simplicity, and because the embodiments disclosed herein are applicable to evolutionary systems beyond 5G NR systems, the gNB-DU may be referred to as a source DU or a target DU.

[0032] The technical solutions described in this application embodiment can be applied to 5G NR systems, and can also be applied to evolution systems after 5G NR systems.

[0033] In this specification, a cell may refer to a component carrier having coverage from signals transmitted from a transmission / reception point, or a component carrier having coverage from signals transmitted from a transmission / reception point.

[0034] In this specification, a candidate cell may refer to a cell that the UE considers for undergoing lower-layer triggered mobility (LTM). A target cell may refer to a cell that the UE switches to via an LTM handover command.

[0035] In this specification, source cell and serving cell can be used synonymously. Similarly, source network node and serving network node can be used synonymously.

[0036] Figure 1 illustrates the message sequence diagram for the Rel-18 LTM procedure for the primary cell. In step 1, using the Radio Resource Control (RRC) configuration in the UE, the UE generates and transmits a Layer 3 (L3) measurement report of at least one candidate cell to the source DU. The at least one candidate cell includes a target cell to which the UE can be handed over by the source DU.

[0037] In step 2, the source DU forwards the L3 measurement report to the CU via uplink RRC message transmission. In step 3, the CU prepares at least one candidate cell for LTM based on the L3 measurement report.

[0038] In steps 4 and 5, the CU initiates the preparation process for at least one candidate cell under the DU, where the target DU can also be the source DU (i.e., the source cell and the target cell belong to the same DU).

[0039] In steps 6 and 7, the CU and the source DU perform a UE context modification process so that the CU can collect additional configuration details for the LTM preparation process.

[0040] In step 8, the CU generates an RRC reconfiguration for at least one candidate cell that is already prepared for LTM. The RRC configuration may include measurement and reporting configuration information for at least one candidate cell, as well as the RRC reconfiguration of at least one candidate cell to be applied on the UE when a cell change to the target cell is triggered.

[0041] In steps 9 to 12, the CU provides the UE with RRC reconfiguration for at least one candidate cell that has been prepared via the source DU, and also receives confirmation of RRC reconfiguration reception (by the UE).

[0042] In step 13, the UE begins reporting Layer 1 (L1) measurements for at least one candidate cell based on RRC reconfiguration. For simplicity, Figure 1 illustrates only a single instance of L1 measurement reporting occurring. However, when multiple candidate cells exist, multiple instances of L1 measurement reporting can occur (e.g., periodic reporting).

[0043] In step 14, based on L1 measurements of at least one candidate cell, the source DU determines the target cell to which the UE should be handed over. As a result, the source DU triggers a timing advance (TA) acquisition of the target cell, enabling the UE to synchronize with the target cell.

[0044] In step 15, once the UE is triggered to acquire the target cell's TA, the UE can suspend any transmission / reception (TX / RX) with the serving cell (source DU and CU) to send a Physical Random Access Channel (PRACH) preamble to the target cell. In cases requiring RF tuning (e.g., if the target cell operates on a different carrier frequency), the UE also tunes its RF before sending the PRACH preamble to the target cell.

[0045] In step 16, the UE transmits a PRACH preamble to the target cell. In step 17, the UE tunes its RD back to the source cell (if necessary) and restores TX / RX with the source cell.

[0046] In step 18, the UE continues with an L1 measurement report as described in step 13.

[0047] In step 19, the source DU determines to trigger a cell change to the target cell and sends a Media Access Control (MAC) element (CE) to trigger the UE to initiate LTM to the target cell. The MAC CE may include the TA of the target cell, which can be obtained through the TA acquisition procedure.

[0048] In steps 20 and 21, if the UE does not have uplink timing synchronization with the target cell, the UE initiates a Random Access Channel (RACH) procedure with the target cell. In step 22, the UE and the network will continue to complete the LTM procedure.

[0049] In general, for L1 / L2 triggered mobility (LTM), the UE reports L1 beam measurements to the source DU, and the source DU can determine when to trigger the mobility procedure for the target cell included in the L1 measurement report. The L1 measurement report can be based on previous L3 measurements provided by the UE, indicating that one or more candidate cells are suitable for the UE to handover.

[0050] Figure 2A and Figure 2B This illustrates LTM carrier aggregation scenarios with different operating frequencies for secondary cells. In carrier aggregation within single connectivity, the UE can be served by a cell group (CG), which may include a primary cell (PCell) and at least one secondary cell (SCell). For simplicity, Figure 2A and Figure 2B Only a single SCell is shown.

[0051] Figure 2A This illustrates a carrier aggregation scenario where the target SCell (i.e., the SCell associated with the target PCell) and the source SCell operate at the same frequency. The source PCell and the target PCell also operate at the same frequency.

[0052] Figure 2B This illustrates a carrier aggregation scenario where the source PCell and target PCell operate at the same frequency. However, the source SCell and target SCell operate at different frequencies.

[0053] for Figure 2B In the scenario shown, when LTM is involved, there may be changes in throughput during dynamic switching, and the embodiments disclosed herein seek to avoid such changes.

[0054] Furthermore, as can be seen from Figure 1, the measurement and reporting of SCells is not considered in the Rel-18 LTM overview. However, even if SCell measurement and reporting were possible, problems would still exist in the current LTM framework, for which the example embodiments disclosed herein provide solutions.

[0055] Problem #1: L1 measurement of SCell When a UE (in carrier aggregation) operates using SCells, overall outages can be improved when beam-specific handovers are used for both SCells and PCells. However, the UE may have capability limitations that restrict the number of beams it can measure for LTM. Including SCell beams in the measurement may exceed the UE's capabilities. In other words, the UE may have a threshold number of beams it can measure, and if the UE measures both SCell and PCell beams together, it may exceed that threshold.

[0056] Furthermore, under the current L1 measurement framework, when a UE needs to measure more candidate cell beams, the UE subsequently needs to configure additional beam positions for each candidate cell to be measured. It may also be necessary to configure associated reporting settings, where the UE uses separate uplink PUCCH / PUSCH resources to report these measurements. Extending the existing mechanism to SCell measurements and measurements along with PCell measurements, and reporting them simultaneously via multiple reports, may be resource-inefficient in terms of reporting resources and UE measurement processing.

[0057] Problem #2: LTM beam switch indication for SCell Currently, in the LTM framework, LTM handover commands only support beam switching indication for PCells. It is desirable to include the TCI status (beam indication) for SCells in an efficient manner with minimal signaling overhead.

[0058] A general solution to overcome the problem outlined in Problem #1 could be that beam-based handover is not required for all SCells of all PCells. In other words, the UE can consider beam-based handover only for those SCells associated with the candidate PCell (including the target PCell). Therefore, L1 measurements can be performed only for a subset of SCells (dynamically depending on traffic and radio conditions).

[0059] Figure 3 illustrates message sequence diagrams including measurement and reporting enhancements for a target secondary cell according to some example embodiments of this disclosure. The example embodiments shown in Figure 3 provide several related solutions to the aforementioned problem #1, and are more specific.

[0060] Referring to the description in Figure 3, in step 1, the UE can be in RRC connection mode with the serving cell at the source DU. In step 2, the UE can indicate its ability to: store additional L1 measurement resources (synchronization signal block (SSB)) configuration and / or support dynamically performing / initiating L1 measurements for the SCell (associated with the candidate PCell).

[0061] Using the current RRC configuration, the UE can perform L3 measurements of signals from candidate cell groups. These signals can be reference signals (RS). In step 3, the UE can transmit an L3 measurement report to the CU, which receives the report via the source DU.

[0062] In steps 4 through 6, based on the L3 measurement report, the CU can decide whether to prepare a candidate cell group for LTM. The CU can send a UE context establishment request to (multiple) target DUs. The CU can use the UE context modification procedure to collaborate with the serving DU to share the candidate cell group configuration.

[0063] In step 7, the UE may receive an RRC reconfiguration from the CU via the source DU. This RRC reconfiguration includes the LTM-RS configuration for the candidate cell group (multiple PCells and their associated SCells). This may also include the measurement and reporting configuration for the SCells (for L1 measurements). In an example embodiment, the measurement and reporting configuration may include a flag (or indication) to distinguish the SCell and its binding (i.e., its association) with the PCell. In other words, this flag (or indication) is included in the configuration for LTM L1 measurements.

[0064] In step 8 (which involves notifying the source DU of the prepared L1 measurement configuration including the PCell and SCell), the CU may notify the source DU of the prepared L1 measurement configuration including the reference signals of the PCell and SCell for each candidate cell group (as part of the RRC reconfiguration). The source DU can use this information to process the received L1 measurement reports including the PCell and SCell for each candidate cell group.

[0065] In steps 9 through 13 (which relate to the first aspect of measurement enhancement (i.e., the solution to problem #1)), the UE can transmit L1 measurement reports for candidate PCells (i.e., PCells of each candidate cell group) to the source DU. Based on the L1 measurement reports of the candidate PCells, the source DU can transmit a Media Access Control (MAC) control element (CE) to activate L1 measurements for the SCell. The MAC CE may include cell indexes (cell indexes of the target PCell and its associated SCells). The UE can identify SCells using flags / indications in the measurement and reporting configuration to distinguish SCells and their bindings to PCells. The MAC CE may also include a specific reference signal configuration to be activated for measuring the target SCell (i.e., the SCell of the target cell group). After activating the target SCell measurement, the UE can begin measuring the reference signals of the SCell associated with the cell index in the MAC CE. Accordingly, the UE transmits the L1 measurement report for the SCell to the source DU.

[0066] In steps 14 through 17 (which relates to the second aspect of measurement enhancement (i.e., the solution to problem #1)), the UE can decide to perform L1 measurements only for those SCells associated with PCells that meet the selection criteria. In other words, the UE can initiate SCell measurements for those SCells associated with a subset of candidate PCells. Selection criteria can be configured via RRC, such as effective timing advance (TA) and / or radio conditions or TCI state activation. In some example embodiments, measurement resources can be activated by network commands before the UE actually begins performing measurements. In one example embodiment, the UE can be configured via RRC / MAC to initiate (additional) SCell measurements for SCells associated with a target PCell, wherein a TA acquisition procedure is performed for that target PCell (or the TA is acquired for that target PCell, e.g., via uplink transmission / UE-based TA acquisition prior to cell handover). In another example embodiment, radio conditions may be that the candidate PCell has already been reported by the UE in the L1 measurement report, or that the measured SCell is associated with those PCells that have cell quality (measured in dB) within the threshold range of the currently serving PCell. In yet another example embodiment, for TCI state activation, if the UE receives activation of the TCI state for a target LTM PCell before PCell handover, the UE can begin measuring those SCells associated with the PCell where the TCI state is activated.

[0067] In steps 18 through 21 (which relates to the third aspect of measurement report enhancement (i.e., the solution to problem #1)), the UE can perform SCell measurements on those SCells associated with the PCell having the highest reported beam. In other words, after transmitting the L1 measurement reports of the candidate PCells in step 19, the UE can decide in step 20 to perform L1 measurements on those SCells associated with the PCell listed in the measurement report as having the best beam. Accordingly, in step 21, the UE can transmit the L1 measurements of those SCells to the UE.

[0068] In steps 22 and 23 (which relate to the fourth aspect of measurement report enhancement (i.e., the solution to problem #1)), the UE may send a single measurement report comprising L1 measurements of the candidate PCell and its associated SCell. In other cases, the UE may send a single measurement report combining measurements of the candidate PCell and its associated SCell. In Rel-18, the main report may include N candidate cells and M beams from each candidate cell, thus reporting a total (N...) in the report instance. M) beams. The UE can be configured to replace N cells (i.e., N PCells) with SCell beams having corresponding M beam measurements. In this case, a single measurement report can include the best (multiple) PCell(s) and the corresponding SCell. For example, it is possible to report the PCell with the strongest beam among all candidate PCells and the remaining (N-1) SCells associated with that PCell. In another example, it is possible to report the top two PCells with the strongest beams among all candidate PCells and then the (N-1) / 2 SCells associated with each of those PCells.

[0069] In step 24 (which relates to the fifth aspect of measurement reporting enhancement (i.e., a solution to problem #1)), the UE can perform L1 measurements on the SCell associated with the candidate PCell and transmit the L1 measurement report in the form of a MAC CE. This can help avoid L1 reporting overhead. In the example embodiment, the report triggering conditions can be configured, for example, based on the quality of the SCell and / or its associated PCell.

[0070] Figure 4 illustrates a message sequence diagram including enhanced Transmission Configuration Indicator (TCI) state handover for a target secondary cell according to an example embodiment of this disclosure. The example embodiment in Figure 4 describes a solution to problem #2.

[0071] For the sake of brevity, the descriptions of steps 1 to 3 are omitted, as they have been previously disclosed in this document.

[0072] In step 4 (which can be considered a preparation phase for TCI state switching), the CU may include the flag "secondary-cell beamswitch" when preparing candidate cells for beam indication of SCells. The target DU may indicate TCI states that are common to a set of SCells. This can be done in the form of a list, which includes a mapping of SCells to their TCI states. The CU may notify the source DU of additional TCI states and their mappings to the SCell list. In other words, for each target cell group, there may be a set of TCI states for PCells that map to each beam of the PCell. For SCells in the target cell group, multiple SCells may have the same coverage, where a single TCI state list may exist for those SCells with the same coverage.

[0073] In step 5, the RRC reconfiguration message may include a list of TCI state-to-SCell mappings for each candidate PCell.

[0074] In step 6, the UE can transmit the L1 measurement report of the candidate PCell to the source DU. In step 7, the UE can transmit the L1 measurement report of the SCell for the TCI group.

[0075] In step 8 (which can be considered the first execution phase for TCI state handover enhancement), the UE can receive an LTM handover command (also known as an "LTM handover signal") from the source DU. The LTM handover command may include an "additional TCI list" for the SCell (either as a new MAC CE or as an extension of the LTM handover command). Based on the mapping in the TCI state list, the UE can identify the SCell corresponding to the TCI state. It should be noted that the UE can receive either an LTM handover command (as a MAC layer message carrying a set of bits) or an LTM handover signal (as a physical layer signal).

[0076] In step 9, the UE can apply the received TCI states to the SCell in the order of the entries in the TCI state list.

[0077] In the second execution phase, the UE may receive a command for TCI state activation prior to the LTM handover command. This prior activation allows the UE to synchronize with the target beam before the actual handover. When L1 measurements of the SCell are configured, the activation command and subsequent LTM handover commands may include the SCell beam and beam index. The activation command may be sent to the UE as a MAC CE and may include the TCI state of the SCell to be measured. In some example embodiments, the MAC CE may also include a target cell identifier (e.g., a physical cell identifier) ​​and a source cell identifier. In example embodiments, the SCells associated with the target PCell may be listed in a bitmap format, where the bitmap indicates which SCell is activated after the cell handover.

[0078] It should be noted that the steps related to the TCI state switching enhancement can be applied to SCell's L1 measurement and reporting, regardless of whether the aforementioned enhancement is present.

[0079] Figures 5A-5B A method 500 for a first aspect of measurement enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown. Method 500 can be performed by a UE.

[0080] In step 502, the UE receives a higher-layer message for the mobility procedure from the source network node serving the UE. The higher-layer message includes LTM configuration information, which includes indications (e.g., flags) for distinguishing at least one SCell in each of one or more candidate cell groups, wherein each candidate cell group includes a PCell and at least one SCell. The higher-layer message may be an RRC message.

[0081] In step 504, the UE performs L1 measurements of the PCell in each candidate cell group based on the configuration information received in the higher-layer message.

[0082] In step 506, the UE sends the first measurement report of L1 measurement of PCell in each candidate cell group to the source network node.

[0083] In step 508, the UE receives a MAC CE from the source network node based on a first measurement report. This MAC CE is used to activate L1 measurements for at least one SCell in a target cell group among one or more candidate cell groups. The MAC CE may activate L1 measurements for at least one SCell in the target cell group based on the cell index of the target cell group. In another example embodiment, the MAC CE may include a reference signal configuration to be activated for L1 measurements of at least one SCell in the target cell group.

[0084] In step 510, the UE performs L1 measurements for at least one SCell of the target cell group based on the MAC CE and configuration information.

[0085] In step 512, the UE sends a second measurement report of at least one L1 measurement of SCell to the source network node.

[0086] Figures 6A-6B A method 600 for a second aspect of measurement enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown. Method 600 can be performed by a UE.

[0087] In step 602, the UE can receive higher-layer messages for the mobility process from the source network node serving the UE, wherein the higher-layer messages include: a) LTM configuration information for one or more candidate cell groups, wherein each candidate cell group includes a PCell and at least one SCell; and b) Selection criteria for the measurement of at least one SCell associated with the PCell of each candidate cell group.

[0088] In step 604, the UE can perform L1 measurements for the PCell of each candidate cell group based on the configuration information.

[0089] In step 606, the UE sends the first measurement report of L1 measurement of PCell in each candidate cell group to the source network node.

[0090] In step 608, the UE determines a subset of PCells based on the first measurement report. This subset of PCells includes PCells in each candidate cell group that meet the selection criteria.

[0091] In step 610, the UE performs an L1 measurement of at least one SCell associated with the PCell of the subset.

[0092] In step 612, the UE sends a second measurement report to the source network node of the L1 measurement of at least one SCell associated with the PCell of the subset.

[0093] This subset of PCells may include those PCells that meet the following criteria: a) The timing has been advanced; b) Possessing cell quality within a threshold range of the source cell served by the source network node; and c) Has an activated TCI state.

[0094] Figures 7A-7B A method 700 for a third aspect of measurement enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown. Method 700 can be performed by a UE.

[0095] In step 702, the UE receives a higher-layer message for the mobility procedure from the source network node serving the UE, wherein the higher-layer message includes LTM configuration information for one or more candidate cell groups, wherein each candidate cell group includes a PCell and at least one SCell.

[0096] In step 704, the UE performs L1 measurements for the PCell of each candidate cell group based on the configuration information.

[0097] In step 706, the UE sends the first measurement report of L1 measurement of PCell in each candidate cell group to the source network node.

[0098] In step 708, the UE determines, based on the first measurement report, that the PCell of the target cell group has the best beam among the PCells of each candidate cell group. In other embodiments, the PCell of the target cell group may be selected based on cell quality, which may be determined based on the first measurement report, which includes the highest reported beam above a threshold among an average of N beams.

[0099] In step 710, the UE performs L1 measurements on at least one SCell in the target cell group based on the configuration information.

[0100] In step 712, the UE sends a second measurement report of L1 measurement of at least one SCell of the target cell group to the source network node.

[0101] Figure 8 A method 800 for a fourth aspect of measurement enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown. Method 800 can be performed by a UE.

[0102] In step 802, the UE receives a higher-layer message for the mobility process from the source network node serving the UE. The higher-layer message includes LTM configuration information for one or more candidate cell groups, wherein each candidate cell group includes a PCell and at least one SCell.

[0103] In step 804, the UE performs L1 measurements on PCells from one or more candidate cell groups and at least one associated SCell.

[0104] In step 806, the UE sends a first measurement report of L1 measurements of the PCell and at least one associated SCell to the source network node. If the first measurement report has N candidate cells (including PCells and SCells) and M beams for each candidate cell, then for X number of PCells in the measurement report, there can be (NX) SCells in the measurement report.

[0105] Figure 9 A method 900 for a fifth aspect of measurement enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown. Method 900 can be performed by a UE.

[0106] In step 902, the UE receives a higher-layer message for the mobility procedure from the source network node serving the UE. The higher-layer message includes LTM configuration information for one or more candidate cell groups, wherein each candidate cell group includes a PCell and at least one SCell.

[0107] In step 904, the UE performs L1 measurements for the PCell of each candidate cell group based on the configuration information.

[0108] In step 904, the UE sends the first measurement report of L1 measurement of PCell in each candidate cell group to the source network node.

[0109] In step 906, the UE performs an L1 measurement of at least one SCell associated with one or more PCells in the first measurement report. In other words, in some embodiments, the measured at least one SCell may be associated with only a subset of the candidate cell groups' PCells.

[0110] In step 908, the UE sends a second measurement report to the source network node, which is a MAC CE and is associated with at least one SCell of L1 measurement of one or more PCells.

[0111] Figures 10-12 Various methods for TCI state switching enhancement are illustrated. TCI state switching enhancement can be applied to L1 measurement and reporting, regardless of whether enhancement is present (as described above).

[0112] For example, Figures 10-12 The various steps in the illustrated method can occur after the following L1 measurements and reporting. The UE receives a higher-layer message for the mobility procedure from the source network node serving the user equipment. This higher-layer message includes LTM configuration information for one or more candidate cell groups, where each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell. The UE performs L1 measurements from the PCell of each candidate cell group based on the configuration information. The UE sends a first measurement report of the L1 measurements from the PCell of each candidate cell group to the source network node. The UE also performs L1 measurements from at least one SCell of each candidate cell group based on the configuration information. Then, the UE sends a second measurement report of the L1 measurements from at least one SCell of each candidate cell group to the source network node.

[0113] Figure 10 A method 1000 for a preparation phase of TCI state handover enhancement for a target secondary cell, according to an example embodiment of the present disclosure, is illustrated. Method 1000 may include steps performed by a CU or a target DU (i.e., a target network node serving a target cell group).

[0114] In step 1002, when preparing a candidate cell group, the CU may include the flag "secondary-cell beam-switch", which is used for beam indication of the SCell.

[0115] In step 1004, the target DU may indicate a common TCI state for a set of SCells, wherein the target DU provides a list with mappings from TCI states to SCells in that set.

[0116] In step 1006, the CU will attach the TCI status and its mapping to the SCell list to notify the DU.

[0117] In step 1008, the CU includes a mapping of the TCI state list to the SCell group for each candidate primary cell (i.e., the PCell of each candidate cell group) in the RRC reconfiguration message for TCI state handover with the SCell (i.e., the SCell associated with each candidate primary cell).

[0118] Figure 11 A method 1100 for the execution phase of TCI state handover enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown.

[0119] In step 1102, the source DU includes an “additional TCI list” for the SCell in the LTM handover command (which is transmitted to the UE), either as a new MAC CE or as an extension of the LTM handover command.

[0120] In step 1104, the UE maps the TCI state to the corresponding SCell based on the mapping identifier in the TCI state list. This allows the UE to apply the TCI state to the SCell based on the mapping between the SCell and the TCI state list.

[0121] Figure 12 A method 1200 for another execution phase of TCI state enhancement for a target secondary cell according to an example embodiment of the present disclosure is shown. Method 1200 can be executed by a source DU.

[0122] In step 1202, the source DU transmits a MAC CE to the UE for activating the TCI state of one or more SCells, wherein the MAC CE includes the TCI state of the one or more SCells.

[0123] In step 1204, the source DU transmits an LTM handover command to the UE to switch to one or more SCells in which the TCI state is active.

[0124] Figures 5A-5B , Figures 6A-6B , Figures 7A-7B , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 The methods shown may include additional steps not shown and / or some steps may be omitted, and therefore should not be construed as limiting the scope of this disclosure. Furthermore, the steps in the above figures do not necessarily occur in the same order as provided herein.

[0125] Figure 13This is a simplified block diagram of a device 1300 for implementing an example embodiment of the present disclosure. Device 1300 is an example of a device that can be configured to implement the various methods and processes described herein. Device 1300 may be a network device (e.g., a source network node / source DU / CU / target DU) or a terminal device (e.g., a UE).

[0126] Device 1300 includes a processor 1304 that controls the operation of the device. Processor 1304 may also be referred to as a central processing unit (CPU). Memory 1302 may include read-only memory (ROM) and random access memory (RAM) and may provide instructions and data to processor 1304. Memory 1302 and processor 1304 may be operatively coupled. Memory 1302 may store computer-readable instructions / computer program code. The computer-readable instructions / computer program code may be pre-stored in memory 1302, or alternatively or additionally received by device 1300 via electromagnetic carrier signals, and / or copied from a physical entity such as a computer program product. Execution of the computer-readable instructions by processor 1304 may cause device 1300 to perform the example embodiments described herein.

[0127] In the context of this document, "memory" (also referred to as "computer-readable medium" or "computer-readable device") can be any non-transitory medium or device that can contain, store, communicate, propagate, or transmit instructions for use by or in conjunction with an instruction execution system, apparatus, or device (e.g., a computer). The term "non-transitory" as used herein is a limitation on the medium itself (i.e., tangible, not tactile), not a limitation on the persistence of data storage (e.g., RAM and ROM).

[0128] The transmitter / receiver (TX / RX) circuit 1306 may include a transmitter 1310 and a receiver 1312, which enable the device 1300 to transmit or receive data. The device 1300 may include (not shown) multiple antennas, transmitters, and receivers.

[0129] In some example embodiments, device 1300 may include features that enable it to perform Figures 5A-5B , Figures 6A-6B , Figures 7A-7B , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 The component is a step / operation in the process. This component can be implemented in any suitable form. For example, the component can be implemented as a circuit (e.g., memory 1302 and processor 1304) or a software module.

[0130] Technical effects: The embodiments disclosed herein also achieve improved throughput during dynamic handover by preventing frequent changes in throughput and maximizing the benefits of L1 measurement beam handover for SCell. The embodiments disclosed herein allow LTM mobility scenarios to be applied to carrier aggregation scenarios.

[0131] Example embodiments of the invention have been disclosed in the accompanying drawings and description. Although specific terminology has been used, it is used in a general and descriptive sense only and not as a limitation. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments disclosed herein without departing from the spirit and scope of the invention, and are consistent with the invention. Other embodiments consistent with the invention will become apparent upon consideration of the description and practice of what has been disclosed herein.

Claims

1. A method comprising: Receives a higher-layer message for a mobility procedure from a source network node serving a user equipment (UE), the higher-layer message including lower-layer triggered mobility (LTM) configuration information, the LTM configuration information including an indication that distinguishes at least one secondary cell (SCell) in each of one or more candidate cell groups from each other, wherein each candidate cell group includes a primary cell (PCell) and the at least one SCell. Based on the configuration information, perform L1 measurements on the PCell in each candidate cell group; Send a first measurement report of the L1 measurement of the PCell in each candidate cell group to the source network node; Based on the first measurement report, a Media Access Control (MAC) Control Element (CE) is received from the source network node, the MAC CE being used to activate a Layer 1 (L1) measurement of at least one SCell of the target cell group among the one or more candidate cell groups; Based on the MAC CE and the configuration information, perform the L1 measurement of at least one SCell of the target cell group; as well as Send a second measurement report of the L1 measurement of the at least one SCell to the source network node.

2. The method according to claim 1, comprising: Based on the received instruction, the association between the at least one SCell and the corresponding PCell of the at least one SCell is determined for each candidate cell group.

3. The method of claim 1, wherein the MAC CE, based on the first measurement report, includes a cell index for the target cell group.

4. The method of claim 3, wherein the MAC CE includes a reference signal configuration to be activated for the L1 measurement of the at least one SCell of the target cell group.

5. The method of claim 1, wherein before receiving the higher-level message, the method comprises: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; as well as The L1 measurement of the at least one SCell is performed based on the activation provided via the MAC CE.

6. The method of claim 1, wherein the UE sends the second measurement report as a MAC CE.

7. A method comprising: Receive higher-level messages for the mobility process from the source network node serving the user equipment, the higher-level messages including: Lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell); and Selection criteria for the measurement of at least one SCell associated with the PCell in each candidate cell group; Based on the configuration information, perform L1 measurements on the PCell in each candidate cell group; Send a first measurement report of the L1 measurement of the PCell in each candidate cell group to the source network node; Based on the first measurement report, a subset of PCells is determined, the subset of PCells including the PCells in each candidate cell group that meet the selection criteria; Perform an L1 measurement of at least one SCell associated with the PCell of the subset; and Send a second measurement report to the source network node of the L1 measurement of at least one SCell associated with the PCell of the subset.

8. The method of claim 7, wherein the selection criteria for said subset of PCells includes at least one of the following: Get the timing ahead of schedule; Having cell quality within a threshold range of the source cell served by the source network node; and It has an active TCI state.

9. The method of claim 7, wherein before receiving the higher-level message, the method comprises: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; as well as The L1 measurement of the at least one SCell is performed based on the activation provided via MAC CE.

10. The method of claim 7, wherein the UE sends a second measurement report as a MAC CE for at least one SCell associated with the PCell of the subset.

11. A method comprising: Receive higher-layer messages for mobility procedures from the source network node serving the user equipment. The higher-layer messages include lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell). Based on the configuration information, perform L1 measurements on the PCell in each candidate cell group; Send a first measurement report of the L1 measurement of the PCell in each candidate cell group to the source network node; Based on the first measurement report, it is determined that the PCell of the target cell group in the one or more candidate cell groups has the best beam in the PCell of each candidate cell group; Based on the configuration information, perform L1 measurements on at least one SCell of the target cell group; as well as Send a second measurement report of the L1 measurement of at least one SCell of the target cell group to the source network node.

12. The method of claim 11, wherein before receiving the higher-level message, the method comprises: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for at least one SCell in each candidate cell group; as well as The L1 measurement of the at least one SCell is performed based on the activation provided via MAC CE.

13. The method of claim 11, wherein the UE sends a second measurement report as a MAC CE for at least one SCell associated with the PCell of the subset.

14. A method comprising: Receive higher-layer messages for mobility procedures from the source network node serving the user equipment. The higher-layer messages include lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell. Based on the configuration information, perform L1 measurements on the PCell from the one or more candidate cell groups and at least one SCell associated with the PCell; as well as Send a first measurement report of the L1 measurement from the PCell of the one or more candidate cell groups and at least one SCell associated with the PCell to the source network node.

15. The method of claim 14, wherein the L1 measurement report comprises: Measurement details for the total number (N) candidate cells; as well as Measurement details for the total number (M) beams for each of the candidate cells, For the first number (X) PCells that serve as candidate cells, there are a second number (NX) SCells that serve as candidate cells.

16. The method of claim 14, wherein before receiving the higher-level message, the method comprises: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; as well as The L1 measurement of the at least one SCell is performed based on the activation provided via the MAC CE.

17. The method of claim 14, wherein the UE sends the first measurement report as a MAC CE.

18. A method comprising: Receive higher-layer messages for mobility procedures from the source network node serving the user equipment. The higher-layer messages include lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell. Based on the configuration information, L1 measurements are performed on the PCell from each candidate cell group; Send a first measurement report of the L1 measurement from the PCell of each candidate cell group to the source network node; Based on the configuration information, perform L1 measurements from at least one SCell in each candidate cell group; as well as A second measurement report of the L1 measurement from at least one SCell of each candidate cell group is sent to the source network node.

19. The method of claim 18, wherein the UE sends the second measurement report as a MAC CE.

20. The method of claim 18, wherein the source network node includes a flag when preparing each candidate cell group, the flag being used for beam indication of at least one SCell in each candidate cell group.

21. The method of claim 20, comprising: Receive an LTM handover signal that includes a TCI status list, the TCI status list including at least one TCI status of at least one SCell of a target cell group mapped to one or more candidate cell groups; as well as Based on the mapping in the TCI state list, the TCI state is applied to at least one SCell of the target cell group.

22. The method of claim 20, comprising: Receive a MAC CE for activating the TCI state of at least one SCell of the target cell group, wherein the MAC CE includes the index of the at least one SCell; as well as Receive an LTM switching signal, the LTM switching signal including the index of the at least one SCell in which the TCI state is activated.

23. The method of claim 7, wherein the MAC CE comprises: The index of the target cell group; as well as The bitmap of at least one SCell.

24. A user equipment (UE), comprising: At least one memory; as well as At least one processor, operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the device to: Receive a higher-layer message for a mobility procedure from the source network node serving the UE. The higher-layer message includes lower-layer triggered mobility (LTM) configuration information, which includes an indication of distinguishing at least one secondary cell (SCell) in each of one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and the at least one SCell. Based on the configuration information, perform L1 measurements on the PCell in each candidate cell group; Send a first measurement report of the L1 measurement of the PCell in each candidate cell group to the source network node; Based on the first measurement report, a Media Access Control (MAC) Control Element (CE) is received from the source network node, the MAC CE being used to activate a Layer 1 (L1) measurement of at least one SCell of the target cell group among the one or more candidate cell groups; Based on the MAC CE and the configuration information, perform the L1 measurement of at least one SCell of the target cell group; as well as Send a second measurement report of the L1 measurement of the at least one SCell to the source network node.

25. The UE of claim 24, wherein the at least one processor is configured to cause the UE to: Based on the received instruction, the association between the at least one SCell and the corresponding PCell of the at least one SCell is determined for each candidate cell group.

26. The UE of claim 24, wherein the MACCE, based on the L1 measurement results of the first measurement report, includes a cell index for the target cell group.

27. The UE of claim 26, wherein the MAC CE includes a reference signal configuration to be activated for the L1 measurement of the at least one SCell of the target cell group.

28. The UE of claim 24, wherein before receiving the higher-layer message, the at least one processor is configured to cause the UE to: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; and The L1 measurement of the at least one SCell is performed based on the activation provided via the MAC CE.

29. The UE of claim 24, wherein the UE transmits the second measurement report of the at least one SCell as a MAC CE.

30. A user equipment (UE), comprising: At least one memory; as well as At least one processor, operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the device to: Receives higher-layer messages for the mobility process from the source network node serving the UE, the higher-layer messages including: Lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell); and Selection criteria for the measurement of at least one SCell associated with the PCell in each candidate cell group; Based on the configuration information, perform L1 measurements on the PCell in each candidate cell group; Send a first measurement report of the L1 measurement of the PCell in each candidate cell group to the source network node; Based on the first measurement report, a subset of PCells is determined, the subset of PCells including the PCells in each candidate cell group that meet the selection criteria; Perform an L1 measurement of at least one SCell associated with the PCell of the subset; and Send a second measurement report to the source network node of the L1 measurement of at least one SCell associated with the PCell of the subset.

31. The UE of claim 30, wherein the selection criterion for said subset of PCells includes at least one of the following: Get the timing ahead of schedule; Having cell quality within a threshold range of the source cell served by the source network node; and It has an active TCI state.

32. The UE of claim 30, wherein prior to receiving the higher-layer message, the at least one processor is configured to cause the UE to: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; and The L1 measurement of the at least one SCell is performed based on the activation provided via MAC CE.

33. The UE of claim 30, wherein the UE transmits the second measurement report as a MAC CE for at least one SCell associated with the PCell of the subset.

34. A user equipment (UE), comprising: At least one memory; as well as At least one processor, operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the device to: Receives higher-layer messages for mobility procedures from the source network node serving the UE, the higher-layer messages including lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell). Based on the configuration information, perform L1 measurements on the PCell in each candidate cell group; Send a first measurement report of the L1 measurement of the PCell in each candidate cell group to the source network node; Based on the first measurement report, it is determined that the PCell of the target cell group in the one or more candidate cell groups has the best beam in the PCell of each candidate cell group; Based on the configuration information, perform L1 measurements on at least one SCell of the target cell group; as well as Send a second measurement report of the L1 measurement of at least one SCell of the target cell group to the source network node.

35. The UE of claim 34, wherein prior to receiving the higher-layer message, the at least one processor is configured to cause the UE to: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; and The L1 measurement of the at least one SCell is performed based on the activation provided via the MAC CE.

36. The UE of claim 34, wherein the UE transmits the second measurement report as a MAC CE for at least one SCell associated with the PCell of the subset.

37. A user equipment (UE), comprising: At least one memory; as well as At least one processor, operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the UE to: Receives a higher-layer message for mobility procedures from the source network node serving the UE. The higher-layer message includes lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell. Based on the configuration information, perform L1 measurements on the PCell from the one or more candidate cell groups and at least one SCell associated with the PCell; as well as Send a first measurement report of the L1 measurement from the PCell of the one or more candidate cell groups and at least one SCell associated with the PCell to the source network node.

38. The UE of claim 37, wherein the first measurement report comprises: Measurement details for the total number (N) candidate cells; as well as Measurement details for the total number (M) beams for each of the candidate cells, For the first number (X) PCells that serve as candidate cells, there are a second number (NX) SCells that serve as candidate cells.

39. The UE of claim 37, wherein before receiving the higher-layer message, the method comprises: Indicates the UE's capability for at least one of the following: Store the LTM configuration information for the at least one SCell in each candidate cell group; as well as The L1 measurement of the at least one SCell is performed based on the activation provided via the MAC CE.

40. The UE of claim 37, wherein the UE transmits the first measurement report as a MAC CE.

41. A user equipment (UE), comprising: At least one memory; as well as At least one processor, operatively coupled to the at least one memory, wherein the at least one processor is configured to cause the UE to: Receive higher-layer messages for mobility procedures from the source network node serving the user equipment. The higher-layer messages include lower-layer triggered mobility (LTM) configuration information for one or more candidate cell groups, wherein each candidate cell group includes a primary cell (PCell) and at least one secondary cell (SCell) associated with the PCell. Based on the configuration information, L1 measurements are performed on the PCell from each candidate cell group; Send a first measurement report of the L1 measurement from the PCell of each candidate cell group to the source network node; Based on the configuration information, perform L1 measurements from at least one SCell in each candidate cell group; as well as A second measurement report of the L1 measurement from at least one SCell of each candidate cell group is sent to the source network node.

42. The UE of claim 41, wherein the UE transmits the second measurement report as a MAC CE.

43. The UE of claim 41, wherein the source network node includes -+ when preparing each candidate cell group, the flag being used for beam indication of at least one SCell in each candidate cell group.

44. The UE of claim 43, comprising: Receive an LTM handover signal that includes a TCI status list, the TCI status list including at least one TCI status of at least one SCell of a target cell group mapped to one or more candidate cell groups; as well as Based on the mapping in the TCI state list, the TCI state is applied to at least one SCell of the target cell group.

45. The UE of claim 43, comprising: Receive a MAC CE for activating the TCI state of at least one SCell of the target cell group, wherein the MAC CE includes the index of the at least one SCell; as well as Receive an LTM switching signal, the LTM switching signal including the index of the at least one SCell in which the TCI state is activated.

46. ​​The UE of claim 45, wherein the MAC CE comprises: The index of the target cell group; as well as The bitmap of at least one SCell.

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