Method and apparatus for layer1 / layer2 triggered mobility (LTM) operation

Abstract

A method performed by a User Equipment (UE) for performing Channel State Information Reference Signal (CSI-RS) measurement reporting for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) is provided. The method receives, from a serving cell, an LTM measurement configuration including a Synchronization Signal Block (SSB) resource set and a CSI-RS resource set. The method receives a report configuration associated with the SSB resource set. The method activates the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication or in response to determining that a specific condition is satisfied. The method starts to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set. The method transmits, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.　

Description

METHOD AND APPARATUS FOR LAYER1 / LAYER2 TRIGGERED MOBILITY (LTM) OPERATION

[0001] The present disclosure is related to wireless communication and, more specifically, to a User Equipment (UE), Base Station (BS), and method for Channel State Information Reference Signal (CSI-RS) measurement reporting for LTM in the wireless communication networks.

[0002] Various efforts have been made to improve different aspects of wireless communication for the cellular wireless communication systems, such as the 5thGeneration (5G) New Radio (NR), by improving data rate, latency, reliability, and mobility. The 5G NR system is designed to provide flexibility and configurability to optimize network services and types, accommodating various use cases, such as enhanced Mobile Broadband (eMBB), massive Machine-Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC). As the demand for radio access continues to grow, however, there exists a need for further improvements in the next-generation wireless communication systems, such as improvements in LTM operations.

[0003] The present disclosure is related to a UE, a BS, and a method for NES in the wireless communication networks.

[0004] In a first aspect of the present disclosure, a UE for performing CSI-RS measurement reporting for LTM is provided. The UE includes at least one processor and at least one non-transitory computer-readable medium that is coupled to the at least one processor and that stores one or more computer-executable instructions. The computer-executable instructions, when executed by the at least one processor, cause the UE to: receive, from a serving cell, an LTM measurement configuration including a Synchronization Signal Block (SSB) resource set and a CSI-RS resource set associated with the SSB resource set; receive, from the serving cell, a report configuration associated with the SSB resource set; activate the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied; start to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set; and transmit, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.

[0005] In some implementations of the first aspect, the specific condition includes at least one of: a first measured SSB quality of the serving cell being lower than a first threshold; a second measured SSB quality of a candidate cell being greater than a second threshold; and the second measured SSB quality of the candidate cell being greater than the first measured SSB quality of the serving cell by at least an offset.

[0006] In some implementations of the first aspect, the dynamic indication includes a Medium Access Control (MAC) Control Element (CE) or Downlink Control Information (DCI) that indicates the CSI-RS resource set. The MAC CE includes an LTM Cell Switch Command (CSC) MAC CE.

[0007] In some implementations of the first aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to deactivate the CSI-RS resource set for LTM measurement in response to determining that at least one of the following conditions is satisfied: reception of a deactivation indication from the serving cell; expiration of a timer started upon activation of the CSI-RS resource set; and the specific condition no longer being satisfied. The one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to stop measuring the CSI-RS resources associated with the CSI-RS resource set in response to deactivating the CSI-RS resource set.

[0008] In some implementations of the first aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to receive, from the serving cell, an indicator indicating a reporting method selected from full SSB reporting, partial SSB reporting, and no SSB reporting. In a case that the reporting method is full SSB reporting, the measurement report includes a first number of measured SSBs and a measurement result of the activated CSI-RS resource set. In a case that the reporting method is partial SSB reporting, the measurement report includes a second number of measured SSBs and the measurement result of the activated CSI-RS resource set, where the first number is greater than the second number. In a case that the reporting method is no SSB reporting, the measurement report includes the measurement result of the activated CSI-RS resource set without measured SSBs.

[0009] In some implementations of the first aspect, the indicator indicating the reporting method is included in the report configuration or the dynamic indication. The report configuration is received via Radio Resource Control (RRC) signaling.

[0010] In some implementations of the first aspect, the measurement report is transmitted via a MAC CE including: a report configuration identifier (ID) identifying the report configuration; a CSI resource set ID identifying the CSI-RS resource set; a field indicating whether absolute values or differential values are used in the measurement report; a CSI-RS resource identifier (CRI); and a measured quality value associated with the CRI.

[0011] In some implementations of the first aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: receive, from the serving cell, an LTM CSC MAC CE indicating the target cell; and perform the LTM operation to switch from the serving cell to the target cell based on the LTM CSC MAC CE. Transmitting the measurement report includes transmitting the measurement report to the target cell upon switching to the target cell.

[0012] In some implementations of the first aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to perform the LTM operation to switch from the serving cell to the target cell. The UE measures the CSI-RS resources associated with the CSI-RS resource set before performing the LTM operation. The LTM operation is a conditional LTM operation or is triggered by an LTM CSC MAC CE.

[0013] In a second aspect of the present application, a BS for configuring CSI-RS measurement reporting for LTM is provided. The BS includes at least one processor and at least one non-transitory computer-readable medium that is coupled to the at least one processor and that stores one or more computer-executable instructions. The computer-executable instructions, when executed by the at least one processor, cause the BS to: transmit, to a UE via a serving cell, an LTM measurement configuration including an SSB resource set and a CSI-RS resource set associated with the SSB resource set; and transmit, to the UE via the serving cell, a report configuration associated with the SSB resource set. The UE activates the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied. The UE starts to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set. The UE transmits, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.

[0014] In some implementations of the second aspect, the specific condition includes at least one of: a first measured SSB quality of the serving cell being lower than a first threshold; a second measured SSB quality of a candidate cell being greater than a second threshold; and the second measured SSB quality of the candidate cell being greater than the first measured SSB quality of the serving cell by at least an offset.

[0015] In some implementations of the second aspect, the dynamic indication includes a MAC CE or DCI that indicates the CSI-RS resource set. The MAC CE includes an LTM CSC MAC CE.

[0016] In some implementations of the second aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the BS to transmit, to the UE via the serving cell, an indicator indicating a reporting method selected from full SSB reporting, partial SSB reporting, and no SSB reporting. In a case that the reporting method is full SSB reporting, the measurement report includes a first number of measured SSBs and a measurement result of the activated CSI-RS resource set. In a case that the reporting method is partial SSB reporting, the measurement report includes a second number of measured SSBs and the measurement result of the activated CSI-RS resource set, where the first number is greater than the second number. In a case that the reporting method is no SSB reporting, the measurement report includes the measurement result of the activated CSI-RS resource set without measured SSBs.

[0017] In some implementations of the second aspect, the indicator indicating the reporting method is included in the report configuration or the dynamic indication. The report configuration is received via RRC signaling.

[0018] In a third aspect of the present application, a method performed by a UE for performing CSI-RS measurement reporting for LTM is provided. The method includes receiving, from a serving cell, an LTM measurement configuration including an SSB resource set and a CSI-RS resource set associated with the SSB resource set; receiving, from the serving cell, a report configuration associated with the SSB resource set; activating the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied; starting to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set; and transmitting, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.

[0019] Aspects of the present disclosure are best understood from the following detailed disclosure when read with the accompanying drawings. Various features are not drawn to scale. Dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

[0020] FIG. 1 is a diagram illustrating an LTM procedure, according to an example implementation of the present disclosure.

[0021] FIG. 2 is a diagram illustrating a first report MAC CE, according to an example implementation of the present disclosure.

[0022] FIG. 3 is a diagram illustrating a second report MAC CE, according to an example implementation of the present disclosure.

[0023] FIG. 4 is a diagram illustrating a third report MAC CE, according to an example implementation of the present disclosure.

[0024] FIG. 5 is a diagram illustrating a fourth report MAC CE, according to an example implementation of the present disclosure.

[0025] FIG. 6 is a flowchart illustrating a method / process performed by a UE for CSI-RS measurement reporting for LTM, according to an example implementation of the present disclosure.

[0026] FIG. 7 is a flowchart illustrating a method / process performed by a BS for configuring CSI-RS measurement reporting for LTM, according to an example implementation of the present disclosure.

[0027] FIG. 8 is a block diagram illustrating a node for wireless communication, according to an example implementation of the present disclosure.

[0028] The following contains specific information related to implementations of the present disclosure. The drawings and their accompanying detailed disclosure are merely directed to implementations. However, the present disclosure is not limited to these implementations. Other variations and implementations of the present disclosure will be obvious to those skilled in the art.

[0029] Unless noted otherwise, like or corresponding elements among the drawings may be indicated by like or corresponding reference numerals. Moreover, the drawings and illustrations in the present disclosure are generally not to scale and are not intended to correspond to actual relative dimensions.

[0030] For the purposes of consistency and ease of understanding, like features may be identified (although, in some examples, not illustrated) by the same numerals in the drawings. However, the features in different implementations may be different in other respects and may not be narrowly confined to what is illustrated in the drawings.

[0031] References to “one implementation,” “an implementation,” “example implementation,” “various implementations,” “some implementations,” “implementations of the present application,” etc., may indicate that the implementation(s) of the present application so described may include a particular feature, structure, or characteristic, but not every possible implementation of the present application necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “In some implementations,” or “in an example implementation,” “an implementation,” do not necessarily refer to the same implementation, although they may. Moreover, any use of phrases like “implementations” in connection with “the present application” are never meant to characterize that all implementations of the present application must include the particular feature, structure, or characteristic, and should instead be understood to mean “at least some implementations of the present application” includes the stated particular feature, structure, or characteristic. The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the equivalent.

[0032] The expression “at least one of A, B and C” or “at least one of the following: A, B and C” means “only A, or only B, or only C, or any combination of A, B and C.” The terms “system” and “network” may be used interchangeably. The term “and / or” is only an association relationship for describing associated objects and represents that three relationships may exist such that A and / or B may indicate that A exists alone, A and B exist at the same time, or B exists alone. The character “ / ” generally represents that the associated objects are in an “or” relationship.

[0033] For the purposes of explanation and non-limitation, specific details, such as functional entities, techniques, protocols, and standards, are set forth for providing an understanding of the disclosed technology. In other examples, detailed disclosure of well-known methods, technologies, systems, and architectures are omitted so as not to obscure the present disclosure with unnecessary details.

[0034] Persons skilled in the art will immediately recognize that any network function(s) or algorithm(s) disclosed may be implemented by hardware, software, or a combination of software and hardware. Disclosed functions may correspond to modules which may be software, hardware, firmware, or any combination thereof.

[0035] A software implementation may include computer-executable instructions and / or Artificial Intelligence (AI) / Machine Learning (ML) module(s) stored on a computer-readable medium, such as memory or other type of storage devices. One or more microprocessors or general-purpose computers with communication processing capability may be programmed with corresponding computer-executable instructions and perform the disclosed network function(s), AI / ML module(s), or algorithm(s). The AI / ML module(s) may be implemented with a supervised learning approach, a semi-supervised learning approach, an unsupervised learning approach (e.g., Transductive approach and Inductive approach), a federated learning approach, or a reinforcement learning (RL) approach, but the present disclosure is not limited thereto. The computer-executable instructions associated with the AI module(s) and / or the ML module(s) may include but are not limited to, data management instructions (e.g., collection instructions, validation instructions…etc.), model monitoring and management instructions (e.g., NW key performance indicators (KPIs) monitoring, model input / output monitoring, model selection / switching / update / upload / download, model (de)activation, model identification, functionality selection…etc.), and / or pre-process input instructions.

[0036] The microprocessors or general-purpose computers may include Application-Specific Integrated Circuits (ASICs), programmable logic arrays, Central Processing Units (CPUs), Tensor Processing Units (TPUs), Graphics Processing Units (GPUs), General-purpose computing on GPUs (GPGPU, or less often GPGP), and / or using one or more Digital Signal Processors (DSPs). Although some of the disclosed implementations are oriented to software installed and executing on computer hardware, alternative implementations implemented as firmware, as hardware, or as a combination of hardware and software are well within the scope of the present disclosure. The computer-readable medium may include, but is not limited to, Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), High Bandwidth Memory (HBM), Magnetoresistive Random Access Memory (MRAM), Ferroelectric Random Access Memory (FRAM), Resistive Random Access Memory (RRAM), Read-Only Memory (ROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory (or other memory technology), Compact Disc Read-Only Memory (CD-ROM) , Digital Versatile Disks (DVD) (or other optical disk storage), magnetic cassettes, magnetic tape, magnetic disk storage (or other magnetic storage devices), or any other equivalent medium capable of storing computer-readable instructions.

[0037] A radio communication network architecture such as a Long-Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, an LTE-Advanced Pro system, or a 5G NR Radio Access Network (RAN), 5G-Advanced (5G-A) system, or an open radio access network (O-RAN) may typically include at least one base station (BS), at least one UE, and one or more optional network elements that provide connection within a network. The BS and one or more optional network elements enable the UE to access a radio network. The UE may communicate with the network, such as a Core Network (CN), an Evolved Packet Core (EPC) network, an Evolved Universal Terrestrial RAN (E-UTRAN), a Next-Generation Core (NGC), a 5G Core (5GC), or an internet via a RAN established by one or more BSs and the network elements / functions.

[0038] A UE may include, but is not limited to, a mobile station, a mobile terminal or device, or a user communication radio terminal. The UE may be a portable radio equipment that includes, but is not limited to, a mobile phone, a tablet, a wearable device, a sensor, a vehicle, a virtual reality (VR) device, an augmented (AR) device, an Internet of Things (IoT) device, an unmanned aerial vehicle (UAV), or a Personal Digital Assistant (PDA) with wireless communication capability. The UE may be configured to receive and transmit signals over an air interface to one or more cells in a RAN. In some implementations, the UE may be an AI / ML-enabled device and / or an AI / ML capable device that is equipped with AI module(s) and / or ML module(s).

[0039] The BS may be configured to provide communication services according to at least a Radio Access Technology (RAT), such as Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM) that is often referred to as 2G, GSM Enhanced Data rates for GSM Evolution (EDGE) RAN (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS) that is often referred to as 3G based on basic Wideband-Code Division Multiple Access (W-CDMA), High-Speed Packet Access (HSPA), LTE, LTE-A, evolved / enhanced LTE (eLTE) that is LTE connected to 5GC, NR (often referred to as 5G), 5G-A, and / or LTE-A Pro. However, the scope of the present disclosure is not limited to these protocols.

[0040] The BS may include, but is not limited to, a node B (NB) in the UMTS, an evolved node B (eNB) in LTE or LTE-A, a radio network controller (RNC) in UMTS, a BS controller (BSC) in the GSM / GERAN, a next-generation eNB (ng-eNB) in an Evolved Universal Terrestrial Radio Access (E-UTRA) BS in connection with 5GC, a next-generation Node B (gNB) in the 5G-RAN or in the 5G Access Network (5G-AN), or any other apparatus capable of controlling radio communication and managing radio resources within a cell. The BS may serve one or more UEs via a radio interface. Although the gNB is used as an example in some implementations within the present disclosure, it should be noted that the disclosed implementations may also be applied to other types of base stations. In some implementations, the BS may be an AI / ML-enabled device and / or an AI / ML capable device that is equipped with AI module(s) and / or ML module(s).

[0041] The BS may be operable to provide radio coverage to a specific geographical area using multiple cells forming the RAN. The BS may support the operations of the cells. Each cell may be operable to provide services to at least one UE within its radio coverage.

[0042] Each cell (may often referred to as a serving cell) may provide services to one or more UEs within the cell’s radio coverage, such that each cell schedules the downlink (DL) (and optionally uplink (UL) resources) to at least one UE within its radio coverage for DL (and optionally UL packet transmissions from the UE). The BS may communicate with one or more UEs in the radio communication system via the cells.

[0043] A cell may allocate sidelink (SL) resources for supporting the Proximity Services (ProSe), LTE SL services, LTE / NR sidelink communication services, LTE / NR sidelink discovery services, and / or LTE / NR Vehicle-to-Everything (V2X) services. In addition, a cell may allocate DL and / or UL resources for supporting Multicast / Broadcast Service (MBS) services, Non-Terrestrial Networks (NTN) services, positioning services, power serving services and / or Network Energy Saving (NES) services.

[0044] In Multi-RAT Dual Connectivity (MR-DC) cases, the primary cell of a Master Cell Group (MCG) or a Secondary Cell Group (SCG) may be referred to as a Special Cell (SpCell). A Primary Cell (PCell) may include the SpCell of an MCG. A Primary SCG Cell (PSCell) may include the SpCell of an SCG. MCG may include a group of serving cells associated with the Master Node (MN), including the SpCell and optionally one or more Secondary Cells (SCells). An SCG may include a group of serving cells associated with the Secondary Node (SN), including the SpCell and optionally one or more SCells.

[0045] As discussed above, the frame structure for NR may support flexible configurations for accommodating various next generation (e.g., 5G) communication requirements, such as Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC), while fulfilling high reliability, high data rate, and low latency requirements. The Orthogonal Frequency-Division Multiplexing (OFDM) technology in the third generation partnership project (3GPP) may serve as a baseline for an NR waveform. The scalable OFDM numerology, such as adaptive sub-carrier spacing, channel bandwidth, and Cyclic Prefix (CP), may also be used.

[0046] Two coding schemes may be considered for NR, specifically, Low-Density Parity-Check (LDPC) code and Polar Code. The coding scheme adaption may be configured based on channel conditions and / or service applications.

[0047] At least the DL transmission data, a guard period, and UL transmission data should be included in a transmission time interval (TTI) of a single NR frame. The respective portions of the DL transmission data, the guard period, and the UL transmission data should also be configurable based on, for example, the network dynamics of NR. SL resources may also be provided in an NR frame to support ProSe services or V2X services.

[0048] Any two or more than two of the following paragraphs, (sub)-bullets, points, actions, behaviors, terms, or claims described in the present disclosure may be combined logically, reasonably, and properly to form a specific method.

[0049] Any sentence, paragraph, (sub)-bullet, point, action, behaviors, terms, or claims described in the present disclosure may be implemented independently and separately to form a specific method.

[0050] Dependency, e.g., “based on”, “more specifically”, “preferably”, “in one embodiment”, “in some implementations”, etc., in the present disclosure is just one possible example which would not restrict the specific method.

[0051] In some implementations, all the designs / embodiment / implementations introduced within this disclosure are not limited to be applied for dealing with the problems discussed within this disclosure. For example, the described embodiments may be applied to solve other problems that exist in the RAN of wireless communication systems. In some implementations, all of the numbers listed within the designs / embodiment / implementations introduced within this disclosure are just examples and for illustration, for example, of how the described methods are executed.

[0052] The terms, definitions, and abbreviations given in the present disclosure are either imported from existing documentation (e.g., European Telecommunications Standards Institute (ETSI), International Telecommunication Union (ITU), or elsewhere) or newly created by 3GPP experts whenever the need for precise vocabulary is identified.

[0053] Examples of some selected terms in the present disclosure are provided as follows.

[0054] The network (NW), cell, camped cell, serving cell, base station, gNB, eNB, and ng-eNB may be interchangeably in the present disclosure. In some implementations, some of these items may refer to the same network entity.

[0055] The Radio Access Technology (RAT) may include, but not limited to, New Radio (NR), Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access (E-UTRA) connected to 5G Core Network (5GC), LTE connected to 5GC, E-UTRA connected to Evolved Packet Core (EPC), and LTE connected to EPC. The proposed mechanism may be applied for UEs in public networks or in private networks, such as non-public network (NPN), standalone NPN (SNPN), and public network integrated NPN (PNI-NPN).

[0056] The proposed mechanism may be used for licensed frequency and / or unlicensed frequency. In addition, the proposed mechanism of conditional configuration selection may be applied to cases in which a UE experiences a radio link failure when configured with conditional configurations.

[0057] System information (SI) may refer to Master Information Block (MIB), System Information Block 1 (SIB1), and other SI. Minimum SI may include MIB and SIB1. Other SI may refer to SIB3, SIB4, SIB5, and other SIB(s).

[0058] Dedicated signaling may refer to (but not limited to) RRC message(s). For example, RRC (Connection) Setup Request message, RRC (Connection) Setup message, RRC (Connection) Setup Complete message, RRC (Connection) Reconfiguration message, RRC Connection Reconfiguration message including the mobility control information, RRC Connection Reconfiguration message without the mobility control information inside, RRC Reconfiguration message including the configuration with sync, RRC Reconfiguration message without the configuration with sync inside, RRC (Connection) Reconfiguration Complete message, RRC (Connection) Resume Request message, RRC (Connection) Resume message, RRC (Connection) Resume Complete message, RRC (Connection) Reestablishment Request message, RRC (Connection) Reestablishment message, RRC (Connection) Reestablishment Complete message, RRC (Connection) Reject message, RRC (Connection) Release message, RRC System Information Request message, UE Assistance Information message, UE Capability Enquiry message, and UE Capability Information message.

[0059] The RRC_CONNECTED UE, RRC_INACTIVE UE, and RRC_IDLE UE may apply the proposed implementations.

[0060] The source cell may be a suitable cell or an acceptable cell.

[0061] A suitable cell is a cell on which a UE may camp. The UE may consider a cell as suitable if the following conditions are fulfilled: (1) The cell is part of either the selected Public Land Mobile Network (PLMN) or the registered PLMN or PLMN of the Equivalent PLMN list, and (2) The cell criteria of the cell are fulfilled. Furthermore, according to the latest information provided by Non-Access Stratum (NAS), the suitable cell is not barred. The suitable cell is part of at least one Tracking Area (TA) that is not part of the list of “Forbidden Tracking Areas”, which belongs to a PLMN that fulfils the condition (1).

[0062] An acceptable cell is a cell on which the UE may camp to obtain limited service, such as originating emergency calls and receiving Earthquake and Tsunami Warning System (ETWS) and Commercial Mobile Alert System (CMAS) notifications. An acceptable cell may fulfil the following requirements, which is the minimum set of requirements to initiate an emergency call and to receive ETWS and CMAS notification in an NR network: (1) the cell is not barred, and / or (2) the cell selection criteria are fulfilled.

[0063] Primary Cell (PCell): The MCG cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure may be referred to as a primary cell.

[0064] Primary SCG (PSCell): For dual connectivity operation, the SCG cell in which the UE performs random access when performing the Reconfiguration with Sync procedure.

[0065] Serving Cell: For a UE in the RRC_CONNECTED state, that is not configured with Carrier Aggregation (CA) or Dual Connectivity (DC), there is only one serving cell which is a primary cell. For a UE in the RRC_CONNECTED state, that is configured with CA / DC, the term ‘serving cells’ is used to denote a set of cells including the Special Cell(s) and all secondary cells. The serving cell may include a PCell, a PSCell, or an SCell.

[0066] Secondary Cell: For a UE configured with CA, a cell that provides additional radio resources on top of the special cell may be referred to as a secondary cell.

[0067] Special Cell (SpCell): For a Dual Connectivity operation, the term Special Cell may include the PCell of the MCG or the PSCell of the SCG depending on whether the MAC entity is associated with the MCG or the SCG, respectively. Otherwise, the term Special Cell may include the PCell.

[0068] Master Cell Group (MCG): In MR-DC, a group of serving cells associated with the master node, including the SpCell (e.g., PCell) and optionally one or more SCells.

[0069] Master node: In MR-DC, the radio access node that provides the control plane connection to the core network. It may be a Master eNB (in E-UTRA-NR Dual Connectivity (EN-DC)), a Master ng-eNB (in NG-RAN E-UTRA-NR Dual Connectivity (NGEN-DC)), or a Master gNB (in NR-NR Dual Connectivity (NR-DC) and NR-E-UTRA Dual Connectivity (NE-DC)).

[0070] Secondary Cell Group (SCG): In MR-DC, a group of serving cells associated with the secondary node, including the SpCell (e.g., PSCell) and optionally one or more SCells.

[0071] Secondary node: In MR-DC, the radio access node, with no control plane connection to the core network, providing additional resources to the UE. It may be an en-gNB (in EN-DC), a Secondary ng-eNB (in NE-DC), or a Secondary gNB (in NR-DC and NGEN-DC).

[0072] Source node: The node from which the UE receives a CSC. The source node may be interpreted as a source MN, a source SN, a source PCell, a source PSCell, or a source gNB.

[0073] Source cell: The cell from which the UE receives a CSC. The source cell may be interpreted as a source PCell, or a source PSCell.

[0074] Candidate node: The node that is associated with the LTM candidate configuration stored by the UE. The candidate node may be interpreted as a candidate MN, a candidate SN, a candidate PCell, a candidate PSCell, or a candidate gNB.

[0075] Candidate cell: The cell that is associated with the LTM candidate configuration stored by the UE. The candidate cell may be interpreted as a candidate PCell, or a candidate PSCell.

[0076] Target node: The node that is associated with the LTM candidate configuration ID in the CSC received by the UE. The target node may be interpreted as a target MN, a target SN, a target PCell, a target PSCell, or a target gNB.

[0077] Target cell: The cell that is associated with the LTM candidate configuration ID in the CSC received by the UE. The target cell may be interpreted as a target PCell, or a target PSCell.

[0078] In the present disclosure, the system information may be associated with the serving cell and / or the candidate / target cell.

[0079] In the wireless cellular network, mobile devices (e.g., UE) may move from the coverage area of one cell to another cell. To avoid the connection interruption and ensure the service continuity, a handover procedure may be applied for the mobile devices when the handover procedure is triggered under certain conditions, e.g., when the signal quality of the source cell becomes poorer than a threshold for a period.

[0080] A handover procedure may be triggered by Layer 3 (L3) measurements and completed through RRC signaling, which triggers Reconfiguration with Synchronization to change the Primary Cell (PCell) and Primary Secondary Cell (PSCell), as well as to release and add Secondary Cells (SCells). In addition, a conditional handover (CHO) may enhance robustness by allowing the mobile device to receive the target cell configuration in advance, for example, when the signal quality between the mobile device and the source cell is stable. Dual Active Protocol Stack (DAPS) handover may reduce the interruption time because the mobile device may maintain two protocol stacks for simultaneous connections with the source cell and the target cell during handover. For example, one protocol stack is associated with the source cell and the other one is associated with the target cell.These handover procedures, including the conditional handover and the DAPS handover, may require a complete Layer 2 (L2) reset and Layer 1 (L1) reset. L2 may refer to the Medium Access Control (MAC) layer, Radio Link Control (RLC) layer, and Packet Data Convergence Protocol (PDCP) layer, and L1 may refer to the Physical (PHY) layer. Complete L1 / L2 reset may result in longer latency, larger overhead and longer interruption time than beam switch mobility. Thus, L1 / L2 triggered mobility (LTM) has been proposed to enable a serving cell change via L1 / L2 signaling, which may reduce the latency, overhead and interruption time during the handover procedures.

[0081] In addition, LTM may allow the UE to perform early downlink and uplink synchronization to shorten the possible experience of interruption. For early downlink synchronization, the UE may activate the downlink beam of the candidate cell in advance. For early uplink synchronization, the UE may obtain the timing advance (TA) by itself or upon the reception of a cell switch command (CSC) to skip the lengthy random access (RA) procedure.

[0082] LTM Procedure

[0083] FIG. 1 is a diagram illustrating an LTM procedure 100, according to an example implementation of the present disclosure. The LTM procedure 100 may include several stages, including LTM preparation 120, early sync 126, LTM cell switch execution 138, and LTM cell switch completion 142.

[0084] The UE 102 may be in the RRC_CONNECTED state 110. The UE 102 may send a measurement report message 112 to the BS 104 (e.g., a gNB). The BS 104 may decide to configure LTM and initiate LTM preparation, such as LTM candidate preparation 114. The BS 104 may transmit an RRC reconfiguration message 116 to the UE including the LTM candidate configurations. The UE 102 may store the LTM candidate configurations and transmit an RRC reconfiguration complete message 118 to the BS 104.

[0085] In the action 122, the UE 102 may perform DL synchronization with the LTM candidate cell(s) before receiving the cell switch command. The UE may activate and deactivate Transmission Configuration Indicator (TCI) states of LTM candidate cell(s), as triggered by the BS 104. In the action 124, the UE 102 may perform UL synchronization with LTM candidate cell(s) before receiving the cell switch command, by using UE-based TA measurement, if configured, and / or by transmitting a preamble towards the candidate cell, as triggered by the BS 104. When UE-based TA measurement is configured, the UE 102 may acquire the TA value(s) of the candidate cell(s) by measurement. The UE 102 may perform early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command as specified in clause 9.2.6 of the 3GPP TS 38.300. This may be done via Contention Free Random Access (CFRA) triggered by a Physical Downlink Control Channel (PDCCH) order from the source cell, following which the UE 102 may send preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the UE 102 may not receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell may be indicated in the cell switch command. The UE 102 may not maintain the TA timer for the candidate cell and may rely on network implementation to guarantee the TA validity.

[0086] The UE 102 may perform L1 measurements on the configured LTM candidate cell(s) and transmit L1 measurement reports 128 to the BS 104. The L1 measurement may be performed as long as RRC reconfiguration 116 is applicable. In the action 130, the BS 104 may decide to execute cell switch to a target cell. The BS 104 may transmit an LTM cell switch command MAC CE 132 triggering cell switch by including a target configuration ID that indicates the index of the candidate configuration of the target cell, a beam indicated with a TCI state or beams indicated with DL and UL TCI states, and a timing advance command for the target cell, if available. In the action 134, the UE 102 may detach from the source cell, switch to the target cell, and apply the candidate configuration indicated by the target configuration ID. In the action 136, the UE 102 may perform the random access procedure towards the target cell, if the UE 102 does not have valid TA of the target cell as specified in clause 5.18.35 of the 3GPP TS 38.321. The action 136 may be an optionally omitted in some implementations, such as in a Random Access Channel (RACH)-less LTM procedure.

[0087] In the action 140, the UE 102 may complete the LTM cell switch procedure by sending an RRC reconfiguration complete message to the target cell. If the UE 102 has performed a RA procedure in the action 136 the UE 102 may consider that LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE 102 may consider that LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data.

[0088] In some implementations, the stages including early sync 126, LTM cell switch execution 138, and LTM cell switch completion 142, may be performed multiple times for subsequent LTM cell switch executions using the LTM candidate configuration(s) provided in the RRC reconfiguration message 116.

[0089] To fully exploit the high capacity enabled by beamforming, it may be necessary to use finer beams derived from CSI-RS. However, the current LTM mechanism supports only the measurement of SSBs as the reference for early downlink (DL) beam activation. In other words, after a cell switch, the UE may use only an SSB beam for data transmission, rather than a CSI-RS beam. The UE may need to subsequently perform a beam management procedure, including CSI-RS measurement and reporting, to obtain a CSI-RS beam. Consequently, if this procedure could be completed before the LTM cell switch, the UE would not experience the data rate drop observed in the current LTM mechanism.

[0090] To achieve this, the UE may need to measure the CSI-RSs of candidate cells before performing the cell switch. However, because the number of CSI-RSs in the candidate cells may be very large, this may impose significant measurement overhead on the UE. Accordingly, a CSI-RS resource set including a group of CSI-RS resources may be preconfigured in advance and dynamically activated or deactivated (e.g., based on the measurement results of the SSBs). In some implementations, the UE may perform the LTM operation to switch from the serving cell to the target cell, where the UE may measure the CSI-RS resources associated with the activated CSI-RS resource set before performing the LTM operation.

[0091] As a result, the report of the CSI-RS may be dynamically adjusted according to the activation or deactivation state of the corresponding CSI-RS resource sets. In addition, since CSI-RS is typically used as the source of finer beams, the reporting of the associated SSB beams may become redundant. This is because the network may utilize the CSI-RS-based measurement results to determine subsequent operations, such as TCI state activation and / or a cell switch command, instead of relying on the measurement results of the associated SSBs. Therefore, this disclosure proposes a dynamic reporting configuration that enables the network to flexibly control the reporting content of the UE when one or more CSI-RS resource sets are activated.

[0092] Scenarios

[0093] The following scenarios may be considered in the present disclosure. A network may include multiple cells, and a UE may or may not support the MR-DC configuration. That is, the UE may receive services from at least two Radio Access Network (RAN) nodes or from only one RAN node. The RAN node may be an evolved node B (eNB) or a next generation node B (gNB). The at least two RAN nodes may include an MN associated with an MCG and at least one SN associated with an SCG. The UE may be equipped with multiple receivers and transmitters, and the UE may be capable of supporting the MR-DC dedicated configurations. The network, having the information that the UE is capable of supporting the MR-DC, may configure the UE with the MR-DC configuration (e.g., the SCG configuration), which may be encapsulated in an RRC Reconfiguration message and transmitted from the serving RAN node to the UE.

[0094] In addition, the involved cells may belong to the same gNB distributed unit (gNB-DU) or to different gNB-DUs. Likewise, the involved gNB-DUs may belong to the same gNB centralized unit (gNB-CU) or to different gNB-CUs. It should be noted that, in an MR-DC operation, the UE may transmit or receive signaling (e.g., RRC signaling) to or from the source PCell, where the signaling may include configuration information of the SCG. Similarly, the UE may transmit or receive signaling to or from the source PSCell, where the signaling may include configuration information of the MCG.

[0095] Configuration of CSI-RS Resource Set and SSB Resource Set

[0096] In some implementations, a UE may be configured with one or more CSI-RS resource sets and one or multiple SSB resource sets, where both types of resource sets may be for LTM measurement.

[0097] An SSB resource set may include one or more SSB resources of one or more candidate cells. An SSB resource may be a physical time / frequency resource on which Synchronization Signal and Physical Broadcast Channel (SS / PBCH) may be transmitted.

[0098] A CSI-RS resource set may include one or more CSI-RS resources of one or more candidate cells. A CSI-RS resource may be a physical time / frequency resource on which CSI-RS may be transmitted.

[0099] In some implementations, the UE may identify an SSB resource set using a resource set ID. In some implementations, the resource set ID may be included in an Information Element (IE) indicating the SSB resource set.

[0100] Option 1: One or more CSI-RS resource sets may be associated with an SSB resource set. In some implementations, the UE may associate an SSB resource set with one or more CSI-RS resource sets if the IEs indicating the one or more CSI-RS resource sets are included in the IE indicating the SSB resource set.

[0101] In some implementations, an SSB resource set may be associated with only a single CSI-RS resource set, and the UE may identify the CSI-RS resource set by using only the resource set ID.

[0102] In some implementations, an SSB resource set may be associated with multiple CSI-RS resource sets. In some implementations, different CSI-RS resource sets associated with the same SSB resource set may not have the same CSI-RS resource set ID, while different CSI-RS resource sets associated with different SSB resource sets may have the same CSI-RS resource set ID. In some implementations, the UE may identify each CSI-RS resource set by using both the resource set ID and the CSI-RS resource set ID.

[0103] Option 2: CSI-RS resource sets may not be associated with SSB resource sets. In some implementations, all the CSI-RS resource sets and all the SSB resource sets may have all different resource set IDs. In some implementations, the UE may identify a CSI-RS resource by using the resource set ID.

[0104] Activation / Deactivation of CSI-RS Resource Set

[0105] In some implementations, a CSI-RS resource set for LTM measurement may be activated and / or deactivated.

[0106] In some implementations, the UE may perform measurement on the CSI-RS resources associated with the CSI-RS resource set if the CSI-RS resource set is activated. For example, the UE may start to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set.

[0107] In some implementations, the UE may not perform measurement on the CSI-RS resources associated with the CSI-RS resource set if the CSI-RS resource set is deactivated. For example, the UE may stop measuring the CSI-RS resources associated with the CSI-RS resource set in response to deactivating the CSI-RS resource set. It may depend on the network (NW) implementation whether the CSI-RS is transmitted while the corresponding CSI-RS resource set is deactivated by the NW.

[0108] In some implementations, the UE may activate the CSI-RS resource set for LTM measurement upon receiving a signaling (e.g., DCI and / or a MAC CE) indicating the CSI-RS resource set. For example, the UE may activate the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell.

[0109] In some implementations, the UE may activate the CSI-RS resource set for LTM measurement when the UE considers some conditions associated with the CSI-RS resource set to be satisfied. In some implementations, the UE may activate the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied.

[0110] In some implementations, the UE may deactivate the CSI-RS resource set for LTM measurement upon receiving a signaling (e.g., DCI and / or a MAC CE) indicating the CSI-RS resource set.

[0111] In some implementations, the UE may deactivate the CSI-RS resource set for LTM measurement upon receiving a signaling (e.g., DCI and / or a MAC CE) indicating other CSI-RS resource sets.

[0112] In some implementations, the UE may deactivate the CSI-RS resource set for LTM measurement in response to determining that at least one of the following conditions is satisfied: reception of a deactivation indication from the serving cell; expiration of a timer started upon activation of the CSI-RS resource set; and the specific condition (e.g., the condition that triggers activation of the CSI-RS resource set) no longer being satisfied.

[0113] In some implementations, the UE may deactivate the CSI-RS resource set for LTM measurement when a timer associated with the CSI-RS resource set expires. In some implementations, the timer may be started (e.g., the UE may start to count the timer to zero, where the initial value of the timer may be pre-configured / pre-defined) when the UE activates the CSI-RS resource set for LTM measurement (e.g., upon / after receiving LTM configuration via the RRC Reconfiguration message). In some implementations, the timer may be stopped when the UE initiates a conditional LTM operation or a conditional handover, or when the UE receives an LTM execution MAC CE. In some implementations, the timer may be triggered, released, maintained, or counted by the MAC entity or the RRC entity. In some implementations, the UE may implement up to two timers, with one associated with the MCG and the other associated with the SCG.

[0114] In some implementations, the UE may deactivate the CSI-RS resource set for LTM measurement when the UE determines that one or more conditions associated with the CSI-RS resource set are not satisfied.

[0115] In some implementations, the UE may report the measurement result of one or more CSI-RS resource sets for LTM according to whether the one or more CSI-RS resource sets are activated or deactivated.

[0116] In some implementations, the UE may perform measurement report of a CSI-RS resource set if the CSI-RS resource set is activated.

[0117] In some implementations, the UE may not perform measurement report of a CSI-RS resource set if the CSI-RS resource set is deactivated.

[0118] In some implementations, the UE may not identify a leave condition as being triggered when an activated CSI-RS resource set is changed to a deactivated state, and may not perform a measurement report in such a case.

[0119] In some implementations, the UE may report the measurement result of an SSB resource set or CSI-RS resource set according to the associated report configuration, where the report configuration may include at least one of the following information.

[0120] - Report configuration ID: the ID to identify the report configuration.

[0121] - Resource ID: the ID corresponding to an SSB and / or CSI-RS resource set with which the report configuration is associated.

[0122] - Report type: the pattern of the physical resources used for carrying the report. The report type may be periodic, semi-persistent on Physical Uplink Control Channel (PUCCH), semi-persistent on Physical Uplink Shared Channel (PUSCH), or aperiodic and associated trigger parameters.

[0123] - Report content: how many beams and / or how many cells the UE may report in a measurement report, and the quantization level of reported beam / cell quality.

[0124] In some implementations, the conditions for activating the measurement of a CSI-RS resource set may include one or more of the following.

[0125] - The measured SSB quality of the serving cell is lower than a threshold for more than a period.

[0126] - The measured SSB quality of a candidate cell is greater than a threshold for more than a period.

[0127] - The measured SSB quality of a candidate cell is offset better than the measured SSB quality of the serving cell for more than a period.

[0128] - The measured SSB quality of a candidate cell is greater than a first threshold and the measured SSB quality of the serving cell is lower than a second threshold for more than a period.

[0129] - The consolidated quality of the serving cell is lower than a threshold for more than a period.

[0130] - The consolidated quality of a candidate cell is greater than a threshold for more than a period.

[0131] - The consolidated quality of a candidate cell is offset better than the consolidated quality of the serving cell for more than a period.

[0132] - The consolidated quality of a candidate cell is greater than a first threshold and the consolidated quality of the serving cell is lower than a second threshold for more than a period.

[0133] The measured SSB quality may be represented by the measured Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or Signal to Interference plus Noise Ratio (SINR) of the SSB. The measured SSB quality of a serving cell may correspond to the SSB beam with the best quality, or to the SSB beam currently used as a Quasi Co-Location (QCL) source for uplink and / or downlink transmission. The threshold, first threshold, second threshold, offset, and period may be configured by the network (e.g., via RRC signaling). The threshold, first threshold, and second threshold may be based on the measurement quality of RSRP, RSRQ, or SINR. The consolidation method may be configured by the network (e.g., via RRC signaling) or may depend on the UE’s implementation. The consolidated quality of a cell may be derived from one or more beams within the cell.

[0134] In some implementations, a cell switch command (CSC) may include a field indicating the candidate cell ID, a field indicating the TCI state to be applied in the target cell, fields indicating the CFRA information, and a field indicating the timing advance (TA) value to be used in the target cell. This CSC may be used by the network and Rel-18 UEs for intra-CU LTM. The CSC may also be used by the network and Rel-19 UEs for inter-CU LTM, intra-CU LTM, or inter-CU SCG LTM. In addition, the CSC may be used by the network and Rel-19 UEs for conditional LTM.

[0135] Separate Report Configuration for CSI-RS and SSB

[0136] In some implementations, when a CSI-RS resource set is activated, the UE may report the measurement result of the CSI-RS resource set according to the report configuration associated with the CSI-RS resource set.

[0137] The UE may associate a CSI-RS resource set with a report configuration if the report configuration includes an IE indicating the identification of the CSI-RS resource set (e.g., an CSI-RS resource set ID).

[0138] The UE may associate a CSI-RS resource set with a report configuration if the report configuration includes an IE indicating the identification of the CSI-RS resource set (e.g., an CSI-RS resource set ID) and the identification (e.g., the ltm-CSI-ResourceConfigId) of the SSB resource set associated with the CSI-RS resource set.

[0139] The UE may associate more than one CSI-RS resource sets with a report configuration if the activated CSI-RS resources are in different CSI-RS resource sets. The number of reported CSI-RS in each of CSI-RS resource sets may not be larger than a configured (pre-configured / pre-defined) value.

[0140] When a CSI-RS resource set is associated with an SSB resource set for LTM measurement, the UE may associate a CSI-RS resource set with a report configuration if the report configuration includes a first IE indicating the identification of the SSB resource set (e.g., the LTM-CSI-ResourceConfigId) and a second IE indicating the identification of the CSI-RS resource set.

[0141] For example, the CSI-RS resources in a CSI-RS resource set and the SSBs in an SSB resource set may be mapped on a one-to-one basis and in sequential order.

[0142] For example, one or more CSI-RS resource sets may be mapped to the same SSB resource set.

[0143] Shared Report Configuration for CSI-RS and SSB, Reporting to Serving Cell

[0144] In some implementations, when an SSB resource set is associated with one or more CSI-RS resource sets and none of the CSI-RS resource sets is activated, the UE may report the measurement result of the SSB resource set according to the report configuration associated with the SSB resource set. In some implementations, when one or more of the CSI-RS resource sets are activated, the UE may report the measurement result of the one or more activated CSI-RS resource sets and the SSB resource set according to the report configuration associated with the SSB resource set.

[0145] The UE may report the measurement result of the CSI-RS resource set(s) and the SSB resource set(s) in the same report.

[0146] In some implementations, the UE may determine the number of reported SSB resource indicators (SSBRI) and the number of reported CSI-RS resource indicators (CRI) by the UE’s implementation.

[0147] In some implementations, the UE may determine the number of reported SSBRIs and the number of CRIs according to the report content included in the report configuration.

[0148] In some implementations, the UE may report the same number of SSBs regardless of whether there is an activated associated CSI-RS resource set. This shared reporting method may be referred to as “Full SSB Reporting.”

[0149] In some implementations, the report content may include a value Nc_ssb indicating the number of reported (LTM candidate) cells for SSB, a value Nssb indicating the number of reported SSB per cell, a value Nc_csi indicting the number of reported cells for CSI-RS, and a value Ncsi indicating the number of reported CSI-RS per cell.

[0150] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc_ssb*Nssb SSBs in a CSI measurement report for LTM, where the UE may report Nc_ssb cells, and for each reported cell, the UE may report Nssb SSBs.

[0151] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of Nc_ssb*Nssb SSBs and Nc_csi*Ncsi CSI-RSs in a CSI measurement report for LTM. In the SSB part, the UE may report Nc_ssb cells, and for each reported cell, the UE may report Nssb SSBs. In the CSI-RS part, the UE may report Nc_csi cells, and for each reported cell, the UE may report Ncsi CSI-RSs.

[0152] In some implementations, the report content may include a value Nc indicating the number of reported cells for SSB, a value Nssb indicating the number of reported SSB per cell, and a value Ncsi indicating the number reported CSI-RS per cell.

[0153] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc*Nssb SSBs in a CSI measurement report for LTM, where the UE may report Nc cells, and for each reported cell, the UE may report Nssb SSBs.

[0154] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of Nc*Nssb SSBs and Nc*Ncsi CSI-RSs in a CSI measurement report for LTM. In the SSB part, the UE may report Nc cells, and for each reported cell, the UE may report Nssb SSBs. In the CSI-RS part, the UE may report Nc cells, and for each reported cell, the UE may report Ncsi CSI-RSs.

[0155] In some implementations, the report content may include a value Nc indicating the number of reported cells for SSB, a value Nssb indicating the number of reported SSB per cell, and a value Ncsi indicating the number of reported CSI-RS.

[0156] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc*Nssb SSBs in a CSI measurement report for LTM, where the UE may report Nc cells, and for each reported cell, the UE may report Nssb SSBs.

[0157] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of Nc*Nssb SSBs and Ncsi CSI-RSs in a CSI measurement report for LTM. In the SSB part, the UE may report Nc cells, and for each reported cell, the UE may report Nssb SSBs. In the CSI-RS part, the UE may report Ncsi CSI-RSs.

[0158] In some implementations, the UE may reduce the number of reported SSBs when there are one or more activated associated CSI-RS resource sets. This shared reporting method may be referred to as “Partial SSB Reporting.” In this case, the UE may report a combination of SSBs and CSI-RSs instead of reporting all SSBs as in “Full SSB Reporting.” That is, compared with “Full SSB Reporting,” some of the SSBs that would otherwise be included in the report may be replaced by CSI-RSs in “Partial SSB Reporting.”

[0159] In some implementations, the report content may include a value Nc_rs indicating the number of reported cells for RSs, a value Nrs indicating the number of reported RSs per cell, a value Nc_csi indicating the number of reported cells for CSI-RSs, and a value Ncsi indicating the number of reported CSI-RS.

[0160] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc_rs*Nrs SSBs in a CSI measurement report for LTM, where the UE may report Nc_rs cells, and for each reported cell, the UE may report Nrs SSBs.

[0161] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of (Nc_rs*Nrs - Nc_csi*Ncsi) SSBs and Nc_csi*Ncsi CSI-RSs in a CSI measurement report for LTM. In the SSB part, the UE may report (Nc_rs*Nrs - Nc_csi*Ncsi) SSBs. In CSI-RS part, the UE may report Nc_csi cells, and for each reported cell, the UE may report Ncsi CSI-RSs.

[0162] In some implementations, the report content may include a value Nc indicating the number of reported cells for RSs, a value Nrs indicating the number of reported RSs per cell, and a value Ncsi indicating the number of reported CSI-RS per cell.

[0163] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc*Nrs SSBs in a CSI measurement report for LTM, where the UE may report Nc cells, and for each reported cell, the UE may report Nrs SSBs.

[0164] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of (Nc*Nrs - Nc*Ncsi) SSBs and Nc*Ncsi CSI-RSs in a CSI measurement report for LTM. In the SSB part, the UE may report Nc cells, and for each reported cell, the UE may report (Nrs - Ncsi) SSBs. In the CSI-RS part, the UE may report Nc cells, and for each reported cell, the UE may report Ncsi CSI-RSs.

[0165] In some implementations, the report content may include a value Nc indicating the number of reported cells for RSs, a value Nrs indicating the number of reported RSs per cell, and a value Ncsi indicating the number of reported CSI-RS.

[0166] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc*Nrs SSBs in a CSI measurement report for LTM, where the UE may report Nc cells, and for each reported cell, the UE may report Nrs SSBs.

[0167] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of (Nc*Nrs - Ncsi) SSBs and Ncsi CSI-RSs in a CSI measurement report for LTM.

[0168] In some implementations, the UE may not report SSBs when there are one or more activated associated CSI-RS resource sets. This shared reporting method may be referred to as “No SSB Reporting.”

[0169] In some implementations, the report content may include a value Nc_ssb indicating the number of reported cells for SSBs, a value Nssb indicating the number of reported SSBs per cell, a value Nc_csi indicating the number of reported cells for CSI-RSs, and a value Ncsi indicating the number of reported CSI-RS.

[0170] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc_ssb*Nssb SSBs in a CSI measurement report for LTM, where the UE may report Nc_ssb cells, and for each reported cell, the UE may report Nssb SSBs.

[0171] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of 0 SSBs and Nc_csi*Ncsi CSI-RSs in a CSI measurement report for LTM, where the UE may report Nc_csi cells, and for each reported cell, the UE may report Ncsi CSI-RSs.

[0172] In some implementations, the report content may include a value Nc indicating the number of reported cells for RSs, a value Nssb indicating the number of reported SSBs per cell, and a value Ncsi indicating the number of reported CSI-RS per cell.

[0173] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc*Nssb SSBs in a CSI measurement report for LTM, where the UE may report Nc cells, and for each reported cell, the UE may report Nssb SSBs.

[0174] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of 0 SSBs and Nc*Ncsi CSI-RSs in a CSI measurement report for LTM, where the UE may report Nc cells, and for each reported cell, the UE may report Ncsi CSI-RSs.

[0175] In some implementations, the report content may include a value Nc_ssb indicating the number of reported cells for SSBs, a value Nssb indicating the number of reported SSBs per cell, and a value Ncsi indicating the number of reported CSI-RS.

[0176] - When no associated CSI-RS resource set is activated, the UE may include the measurement results of Nc_ssb*Nssb SSBs in a CSI measurement report for LTM, where the UE may report Nc_ssb cells, and for each reported cells, the UE may report Nssb SSBs.

[0177] - When one or more CSI-RS resource sets are activated, the UE may include the measurement results of 0 SSBs and Ncsi CSI-RSs in a CSI measurement report for LTM.

[0178] In some implementations, the selection of reported (LTM candidate) cells and SSBs / CSI-RSs may be based on the UE’s implementation.

[0179] In some implementations, the selection of shared reporting methods (e.g., Full SSB, Partial SSB, No SSB) may be based on UE’s implementation.

[0180] In some implementations, the selection of shared reporting methods (e.g., Full SSB, Partial SSB, No SSB) may be based on the RRC pre-configuration. More specifically, an indication IE indicating the shared reporting methods may be configured in the RRC pre-configuration.

[0181] The indication IE may be included in the report configuration associated with the SSB resource set. For different SSB resource sets, the shared reporting methods may be different.

[0182] In some implementations, the indication IE may take an ENUMERATED format corresponding to the indicated shared reporting method. For example, if the indication IE takes a first value (e.g., ‘full_ssb’), the UE may consider the shared reporting method to be Full SSB Reporting. For example, if the indication IE take a second value (e.g., ‘partial_ssb’), the UE may consider the shared reporting method to be Partial SSB Reporting. For example, if the indication IE takes a third value (e.g., ‘no_ssb’), the UE may consider the shared reporting method to be No SSB Reporting.

[0183] In some implementations, the UE may select the shared reporting methods (e.g., Full SSB, Partial SSB, No SSB) according to the signaling (e.g., DCI and / or a MAC CE) that activates the measurement of CSI-RS resource sets. More specifically, the signaling may include a field indicating the shared reporting method.

[0184] In some implementations, if the field takes a first value (e.g., ‘00’), the UE may consider the shared reporting method to be Full SSB Reporting; if the field takes a second value (e.g., ‘01’), the UE may consider the shared reporting method to be Partial SSB Reporting; if the field takes a third value (e.g., ‘10’), the UE may consider the shared reporting method to be No SSB Reporting.

[0185] In some implementations, if a first shared reporting method has been indicated via a first signaling that activates a first CSI-RS resource set associated with an SSB resource set, then upon receiving a second signaling indicating a second shared reporting method and activating a second CSI-RS resource set associated with the same SSB resource set, the UE may apply the second shared reporting method for the report configuration associated with that SSB resource set.

[0186] In some implementations, if a first shared reporting method has been indicated via a first signaling that activates a first CSI-RS resource set associated with an SSB resource set, then upon receiving a second signaling indicating a second shared reporting method and activating a second CSI-RS resource set associated with the same SSB resource set, the UE may ignore the indication of the shared reporting method in the second signaling and keep applying the first shared reporting method for the report configuration associated with the SSB resource set.

[0187] Report Configuration for CSI-RS and SSB, where CSI-RS Measurement is Reported to Target Cell

[0188] In some implementations, the UE may measure SSBs in an SSB resource set and may measure CSI-RS resources in a CSI-RS resource set associated with a candidate cell while connected to the serving cell. The UE may report only the SSB measurement results to the serving cell during this time. Upon execution of a cell switch to a target cell, the UE may report the measurement results of CSI-RS resources in the CSI-RS resource set to the target cell, which may be one of the candidate cells. The UE may report only the CSI-RS resources associated with the target cell, or may report the CSI-RS resources associated with multiple candidate cells, including the target cell.

[0189] One or more SSBs in the SSB resource set may be associated with the serving cell. One or more SSBs in the SSB resource set may be associated with the candidate cell. The SSB may be a Cell-Defining SSB (CD-SSB) or On-Demand SSB (OD-SSB).

[0190] The CSI-RS resource set may be activated for measurement when the UE is connected to the serving cell. The activation may be indicated by a MAC CE and / or DCI from the serving cell or may occur according to a preconfigured condition. The activation may be indicated before or after the UE receives the CSC MAC CE. In some implementations, the CSI-RS resource set may be implicitly activated when the UE receives the corresponding configuration.

[0191] In some implementations, the UE may report the measurement results of the CSI-RS resource set to the candidate cell indicated by the CSC MAC CE via RRC signaling (e.g., a MeasurementReport message), via a MAC CE, and / or via Uplink Control Information (UCI).

[0192] The UE may transmit the RRC signaling / MAC CE / UCI with an uplink grant scheduled after an RA procedure.

[0193] The UE may transmit the RRC signaling / MAC CE with a configured uplink grant that is preconfigured in the stored RRC Reconfiguration message associated with the candidate cell. In some implementations, the configured uplink grant may be configured via an LTM configuration (e.g., the LTM-Config).

[0194] The UE may select certain measurement results from the beams associated with a candidate cell to report to that candidate cell. The selected beams may include one or more SSB beams and / or one or more CSI-RS beams. The method of selecting the beams may depend on the UE’s implementation. In some implementations, the number of selected SSB beams and CSI-RS beams may be determined based on the UE’s implementation or may be configured by the network, where the configuration may be included in the LTM-Config, the LTM-Candidate associated with the candidate cell, or the LTM-CSI-ReportConfig associated with the serving cell or candidate cell. In some implementations, the UE may be required to report only the Top K beams to the candidate cell, where the value of K may be configured by the candidate cell. The Top K beam may be defined as a beam with a measured RSRP or SINR that ranks within the highest K among all measured beams, where K is a positive integer.

[0195] The UE may transmit the UCI according to the LTM-CSI-ReportConfig included in the RRCReconfiguration associated with the candidate cell. In some implementations, the UE may transmit the UCI according to the LTM-CSI-ReportConfig associated with the CSI-RS resource set. More specifically, the UE may consider that a CSI-RS resource set and an LTM-CSI-ReportConfig are associated if the CSI-RS resource set ID is included in the LTM-CSI-ReportConfig.

[0196] In some implementations, the UE may determine how to report the measurement results of the CSI-RS resource set to the candidate cell according to a preconfigured indication.

[0197] More specifically, the indication may be included in the LTM-Config IE, in the LTM-Candidate IE associated with the candidate cell, in the LTM-CSI-ReportConfig associated with the serving cell, or in the LTM-CSI-ReportConfig associated with the candidate cell.

[0198] In some implementations, the indication may be an ENUMERATED {‘true’} value. If the indication is present, the UE may use RRC signaling for transmitting the measurement report of the CSI-RS resource set; otherwise, the UE may use UCI for transmitting the measurement report of the CSI-RS resource set.

[0199] In some implementations, the indication may be an ENUMERATED value. If the indication is a first value (e.g., ‘rrc’), the UE may use RRC signaling for transmitting the measurement report of the CSI-RS resource set; if the indication is a second value (e.g., ‘mac’), the UE may use MAC CE for transmitting the measurement report of the CSI-RS resource set; if the indication is a third value (e.g., ‘uci’), the UE may use UCI for transmitting the measurement report of the CSI-RS resource set.

[0200] In some implementations, the UE may report the measurement results of the CSI-RS resource set to the candidate cell according to a preconfigured indication.

[0201] More specifically, the indication may be included in the LTM-Config IE, in the LTM-Candidate IE associated with the candidate cell, in the LTM-CSI-ReportConfig associated with the serving cell, or in the LTM-CSI-ReportConfig associated with the candidate cell.

[0202] In some implementations, the indication may be an ENUMERATED {‘true’} value.

[0203] In some implementations, if the indication is present, the UE may report the measurement results of the CSI-RS resource set to the candidate cell.

[0204] In some implementations, if the indication is absent, the UE may report the measurement results of the CSI-RS resource set to the candidate cell.

[0205] In some implementations, if the indication is present, the UE may not report the measurement result of the CSI-RS resource set to the candidate cell.

[0206] In some implementations, if the indication is absent, the UE may not report the measurement results of the CSI-RS resource set to the candidate cell.

[0207] In some implementations, if the indication is present, the UE may transmit the shared SSB and CSI-RS report to the serving cell, as described previously.

[0208] In some implementations, if the indication is absent, the UE may transmit the shared SSB and CSI-RS report to the serving cell, as described previously.

[0209] In some implementations, if the indication is present, the UE may report the measurement results of CSI-RS resource set if at least one of the following conditions is also met: the measured result of SSB is higher than a defined threshold; the candidate cell is operated in inter-frequency band; and the PDCP buffer of the UE is not empty.

[0210] In some implementations, after a cell switch, the UE may be configured with a report configuration associated with a CSI-RS resource set in the candidate cell. The UE may consider the report configuration to be activated (e.g., the UE may transmit the measurement report of the CSI-RS resource set according to the report configuration) if it has a valid measurement result of the CSI-RS resource set. Otherwise (e.g., if the UE does not have a valid measurement result), the UE may consider the report configuration to be deactivated (e.g., the UE may not transmit the measurement report according to the report configuration).

[0211] In some implementations, the method for determining whether a measurement result of the CSI-RS resource set is valid may depend on the UE’s implementation.

[0212] In some implementations, if the CSI-RS resource set was activated in the serving cell and was not deactivated until the UE receives the CSC MAC CE, the UE may consider that the measurement result of the CSI-RS resource set is valid.

[0213] In some implementations, if a timer associated with the CSI-RS resource set is still running when the UE receives the CSC MAC CE, the UE may consider that the measurement result of the CSI-RS resource set is valid. More specifically, the timer may be started / restarted every time when the UE obtains a measurement result of the CSI-RS resource set. In some implementations, the UE may stop the timer when the UE receives the CSC MAC CE. In some implementations, the initial value of the timer may be configured by the network via RRC signaling (e.g., RRC reconfiguration message, LTM-Config IE, LTM-Candidate IE).

[0214] In some implementations, if the measurement result is invalid, the UE may report a specific value in the reporting content to reflect this situation. The specific value may be an infinite value.

[0215] CSI-RS Measurement Activation upon Cell Switch

[0216] In some implementations, the UE may start measuring the CSI-RS resources in a CSI-RS resource set associated with a candidate cell upon receiving a cell switch command (CSC), and the UE may transmit the measurement report of the CSI-RS resource set to the candidate cell.

[0217] In some implementations, the CSC may include a field indicating one or more CSI-RS resource sets to indicate the CSI-RS resource sets to be activated upon cell switch. In some implementations, the field may take the value corresponding to the CSI-RS resource set ID configured in the LTM-Config. In some implementations, the field may take the value corresponding to the CSI-RS resource set ID configured in the RRCReconfiguration associated with the candidate cell.

[0218] In some implementations, the UE may transmit the measurement report of the CSI-RS resource set to the candidate cell according to the configuration in the associated report configuration, which may be included in the RRCReconfiguration associated with the candidate cell.

[0219] In some implementations, the UE may only report the valid measurement results to the candidate cell. In some implementations, the UE may report all measurement results regardless of whether the measurement is valid or not. A specific value may be reported if the corresponding measurement is invalid.

[0220] In some implementations, the UE may report partial measurement results of the CSI-RS resource set. The number of beams to be reported may be configured by the candidate cell. For example, the UE may report the Top K beams, where the UE may rank the measured beams based on RSRP or SINR and reports only the information of the highest K beams.

[0221] MAC CE-based Reporting

[0222] In some implementations, the UE may report the LTM measurement results via a MAC CE to the network.

[0223] In some implementations, the UE may report the LTM measurement results to the serving cell.

[0224] In some implementations, the UE may report the LTM measurement results to the candidate cell after receiving the cell switch command. In some implementations, the UE may report the LTM measurement results to the target cell that is indicated in the cell switch command.

[0225] In some implementations, the report may include a field indicating the ID identifying the CSI report configuration (e.g., LTM-CSI-ReportConfigId).

[0226] In some implementations, the report may include a field indicating the ID identifying the CSI resource configuration (e.g., LTM-CSI-ResourceConfigId).

[0227] In some implementations, the report may include a field (e.g., the A / D field) indicating whether absolute values or differential values are used in the report. More specifically, if the field is set to a first value (e.g., 0), the UE may report absolute values for all the measurement quantities; if the field is set to a second value (e.g., 1), the UE may report an absolute value in the first measurement quality field and differential values in the remaining measurement quality fields.

[0228] In some implementations, the report may include Ns SSB measurement results and Nc CSI-RS measurement results.

[0229] In some implementations, an SSB measurement result may include a field indicating an SSB identity (e.g., SSBRI) and a field indicating the value of the measured quality (e.g., the RSRP, the RSRQ, the SINR) of the SSB.

[0230] In some implementations, a CSI-RS measurement result may include a field indicating a CSI-RS identity (e.g., CRI) and a field indicating the value of the measured quality (e.g., the RSRP, the RSRQ, the SINR) of the CSI-RS.

[0231] In some implementations, the UE may determine the value of Ns and the value of Nc according to the configuration / indication from the network. More specifically, the determination and configuration / indication method may correspond to one of the reporting methods, such as “Full SSB Reporting”, “Partial SSB Reporting”, and “No SSB Reporting.”

[0232] In some implementations, the UE may determine the values of Ns and Nc based on its implementation. More specifically, if there is no configuration or indication from the network specifying the values of Ns and Nc, the UE may determine these values according to its implementation.

[0233] In some implementations, the report may include a bitmap field indicating which SSBs and / or CSI-RSs are reported. A bit in the bitmap field may correspond to an SSB and / or a CSI-RS resource in the associated CSI resource set. The size of the bitmap field may be equal to the number of configured SSB and / or CSI-RS resources in the associated CSI resource set. For a given bit in the bitmap field, the UE may set the bit to a first value (e.g., 0) if the corresponding SSB and / or CSI-RS is not included in the report, or to a second value (e.g., 1) if the corresponding SSB and / or CSI-RS is included in the report.

[0234] In some implementations, the report may include the indication of whether the corresponding measurement result is an SSB measurement result or a CSI-RS measurement result (e.g., an RS type indicator).

[0235] More specifically, the UE may include the indication of whether the corresponding measurement result is an SSB measurement result or a CSI-RS measurement result in the report if the number of reported SSB and the number of CSI-RS is not configured by the network.

[0236] In some implementations, the indication may be a field including one bit, where the value of the bit may indicate the RS type. For example, a value of ‘0’ may indicate that the corresponding measurement result is an SSB measurement result, and a value of ‘1’ may indicate that the corresponding measurement result is a CSI-RS measurement result. In another example, a value of ‘0’ may indicate a CSI-RS measurement result, and a value of ‘1’ may indicate an SSB measurement result.

[0237] FIG. 2 is a diagram illustrating a first report MAC CE 200, according to an example implementation of the present disclosure. The number of reported SSBs (e.g., Ns) and the number of reported CSI-RSs (e.g., Nc) in the first report MAC CE 200 may be configured by the network. The first report MAC CE 200 may include a report configuration ID, a CSI resource set ID, Ns SSBRIs, Ns SSB measured quality values, Nc CRIs, and Nc CSI-RS measured quality values.

[0238] FIG. 3 is a diagram illustrating a second report MAC CE 300, according to an example implementation of the present disclosure. The number of reported SSBs (Ns) and the number of reported CSI-RSs (Nc) in the second report MAC CE 300 may not be configured by the network and may be determined based on the UE’s implementation. The second report MAC CE 300 may include a report configuration ID, a CSI resource set ID, (Nc+Ns) measured quality values, an RS type indicator for each of the (Nc+Ns) measured quality values, and an SSBRI or CRI corresponding to each of the (Nc+Ns) measured quality values.

[0239] FIG. 4 is a diagram illustrating a third report MAC CE 400, according to an example implementation of the present disclosure. The number of reported SSBs (Ns) and the number of reported CSI-RSs (Nc) in the third report MAC CE 400 may not be configured by the network and may be determined based on the UE’s implementation. The third report MAC CE 400 may include a report configuration ID, a CSI resource set ID, (Nc+Ns) measured quality values, an RS type indicator for each of the (Nc+Ns) measured quality values, and an SSBRI or CRI corresponding to each of the (Nc+Ns) measured quality values. The third report MAC CE 400 may include an additional field A / D indicating whether the measurement qualities (e.g., other than the first measurement quality) are absolute values or differential values.

[0240] FIG. 5 is a diagram illustrating a fourth report MAC CE 500, according to an example implementation of the present disclosure. The number of reported SSBs (Ns) and the number of reported CSI-RSs (Nc) in the fourth report MAC CE 500 may not be configured by the network and may be determined based on the UE’s implementation. The fourth report MAC CE 500 may include a report configuration ID, a CSI resource set ID, Ns SSB measured quality values, and Nc CSI-RS measured quality values. The fourth report MAC CE 500 may include a field A / D indicating whether the measurement qualities (e.g., other than the first measurement quality) are absolute values or differential values. The fourth report MAC CE 500 may include a bitmap field that is used to indicate which SSBs (e.g., S1, S2, …, Si) and / or which CSI-RSs (e.g., C1, C2, …, Cj) are reported.

[0241] It should be noted that the bit widths of the fields illustrated in FIGS. 2 through 5 are exemplary and not limiting. For example, although the bit widths of the report configuration ID, the CSI resource ID, and the A / D field in FIG. 5 are 3, 3, and 2, respectively, these bit widths may vary in different implementations and are not limited to those shown in the figure.

[0242] In some implementations, the CRI in the measurement report (e.g., as shown in FIGS. 2 through 4) may be the CSI-RS ID in the stored ltm-Candidate IE associated with the candidate cell. For example, the field with CRI = 8 may indicate the beam with CRI = 8 configured in the RRCReconfiguration of the candidate cell.

[0243] In some implementations, the measurement quality value of the first reported RS may be an absolute value and may serve as a reference for the measurement quality values of the other reported RSs. The measurement quality values of the other reported RSs may be differential values that use the measurement quality value of the first reported RS as the reference.

[0244] In some implementations, the CRI in the measurement report may be the CSI-RS ID in the ltm-CSI-ResourceConfig IE. In some implementations, the CRI may be one-to-one mapped to the CSI-RS IDs in the ltm-CSI-ResourceConfig IE with a predefined (e.g., ascending or descending) order. For example, if the ltm-CSI-ResourceConfig includes a list of CSI-RS IDs as {1, 3, 5, 7, 8, 9, 12, 15}, the field with CRI=8 may indicate the beam with CRI=15 configured in the RRCReconfiguration of the candidate cell.

[0245] Example of LTM Measurement

[0246] In some implementations, a UE may be configured with an SSB resource set and an associated CSI-RS resource set for LTM measurement. For example, the UE may associate the SSB and CSI-RS resource sets if they are configured in the same LTM-CSI-ResourceConfig IE. The UE may be configured with a report configuration associated with the SSB resource set. For example, the UE may associate the SSB resource set with the report configuration if the report configuration includes the index of the SSB resource set. In some implementations, the report configuration may include an indication of the shared reporting method, a first value indicating the number of reported cells, a second value indicating the number of reported SSBs per cell, and a third value indicating the number of reported CSI-RSs per cell.

[0247] In some implementations, upon receiving the LTM configuration, the UE may consider the CSI-RS resource set for LTM measurement to be deactivated. The UE may perform measurements only on the SSBs associated with the SSB resource set and may report the measurement results of the SSBs according to the report configuration. The UE may include in the measurement report the results of a number of SSBs, where the number may equal the first value multiplied by the second value in the report configuration.

[0248] In some implementations, upon receiving a MAC CE indicating the activation of the CSI-RS resource set, the UE may start measuring the CSI-RS resources associated with the CSI-RS resource set. The UE may also check the indication in the report configuration to determine the report content as follows:

[0249] - If the indication is a first indication value (e.g., ‘full_ssb’), the UE may consider that Full SSB Reporting is indicated. For each report instance, the UE may include in the measurement report the measurement results of a number of SSBs, where the number may equal the first value multiplied by the second value in the report configuration, and a number of CSI-RSs, where the number may equal the first value multiplied by the third value in the report configuration.

[0250] - If the indication is a second indication value (e.g., ‘partial_ssb’), the UE may consider that Partial SSB Reporting is indicated. For each report instance, the UE may include in the measurement report the measurement results of a number of SSBs, where the number may equal the first value multiplied by the second value minus the first value multiplied by the third value in the report configuration, and a number of CSI-RSs, where the number may equal the first value multiplied by the third value in the report configuration.

[0251] - If the indication is a third indication value (e.g., ‘no_ssb’), the UE may consider that No SSB Reporting is indicated. For each report instance, the UE may include in the measurement report only a number of CSI-RSs, where the number may equal the first value multiplied by the third value in the report configuration.

[0252] In some implementations, upon receiving a MAC CE indicating the deactivation of the CSI-RS resource set, the UE may stop measuring the CSI-RS resources associated with that resource set. The UE may perform measurements only on the SSBs associated with the SSB resource set, and may include in the measurement report the results of a number of SSBs, where the number may equal the first value multiplied by the second value in the report configuration.

[0253] FIG. 6 is a flowchart illustrating a method / process 600 performed by a UE for CSI-RS measurement reporting for LTM, according to an example implementation of the present disclosure. In the action 602, the process 600 may start by receiving, from a serving cell, an LTM measurement configuration including an SSB resource set and a CSI-RS resource set associated with the SSB resource set. In some implementations, one or more CSI-RS resource sets may be mapped to the same SSB resource set.

[0254] In the action 604, the process 600 may receive, from the serving cell, a report configuration associated with the SSB resource set. In the action 606, the process 600 may activate the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied.

[0255] In some implementations, the specific condition may include at least one of the following: a first measured SSB quality of the serving cell being lower than a first threshold; a second measured SSB quality of a candidate cell being greater than a second threshold; and the second measured SSB quality of the candidate cell being greater than the first measured SSB quality of the serving cell by at least an offset.

[0256] In some implementations, the dynamic indication may include a MAC CE or DCI that indicates the CSI-RS resource set. In some implementations, the MAC CE that indicates the CSI-RS resource set may include an LTM CSC MAC CE.

[0257] In the action 608, the process 600 may start to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set. In the action 610, the process 600 may transmit, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration. The process 600 may then end.

[0258] For example, based on the LTM measurement configuration in action 602 and the report configuration in action 604, three CSI-RS resource sets may be associated with the SSB resource set corresponding to the report configuration. The UE may consider the default activation state of these three CSI-RS resource sets to be deactivated. In action 606, the UE may activate one of these three CSI-RS resource sets and may start to measure CSI-RS resources associated with the activated CSI-RS resource set.

[0259] In some implementations, the measurement report may be transmitted via a MAC CE that includes the following fields: a report configuration ID identifying the report configuration; a CSI resource set ID identifying the CSI-RS resource set; a field indicating whether absolute values or differential values are used in the measurement report; a CRI; and a measured quality value associated with the CRI.

[0260] In some implementations, the UE may receive, from the serving cell, an LTM CSC MAC CE indicating the target cell. The UE may perform the LTM operation to switch from the serving cell to the target cell based on the LTM CSC MAC CE. In some implementations, in action 610, the UE may transmit the measurement report to the target cell upon switching to the target cell. In some implementations, the UE may transmit the measurement report associated with the activated CSI-RS resource set before switching to the target cell. In some implementations, the UE may transmit the measurement report associated with the activated CSI-RS resource set after switching to the target cell.

[0261] In some implementations, the UE may deactivate the CSI-RS resource set for LTM measurement in response to determining that at least one of the following conditions is satisfied: reception of a deactivation indication from the serving cell; expiration of a timer started upon activation of the CSI-RS resource set; and the specific condition no longer being satisfied. The UE may stop measuring the CSI-RS resources associated with the CSI-RS resource set in response to deactivating the CSI-RS resource set.

[0262] In some implementations, the UE may receive, from the serving cell, an indicator indicating a reporting method selected from full SSB reporting, partial SSB reporting, and no SSB reporting. In a case that the reporting method is full SSB reporting, the measurement report may include a first number of measured SSBs and a measurement result of the activated CSI-RS resource set. In a case that the reporting method is partial SSB reporting, the measurement report may include a second number of measured SSBs and the measurement result of the activated CSI-RS resource set, where the first number may be greater than the second number. In a case that the reporting method is no SSB reporting, the measurement report may include the measurement result of the activated CSI-RS resource set without measured SSBs.

[0263] In some implementations, the indicator indicating the reporting method may be included in the report configuration (e.g., the report configuration received in action 604) or the dynamic indication (e.g., the dynamic indication that activates the CSI-RS resource set in action 606). The report configuration may be received via RRC signaling.

[0264] In some implementations, the UE may perform the LTM operation to switch from the serving cell to the target cell. The UE may measure the CSI-RS resources associated with the CSI-RS resource set before performing the LTM operation. The LTM operation may be a conditional LTM operation or may be triggered by an LTM CSC MAC CE.

[0265] The steps / actions shown in FIG. 1 should not be construed as necessarily order dependent. The order in which the process is described is not intended to be construed as a limitation. Moreover, some of the actions shown in FIG. 1 may be omitted in some implementations and one or more actions shown in FIG. 1 may be combined.

[0266] The technical problem addressed by the present disclosure is that in the conventional LTM mechanism, the UE only measures SSBs as the reference for early downlink beam activation, and therefore may only use an SSB beam for data transmission after a cell switch, resulting in a temporary data rate drop and reduced mobility performance. In addition, allowing the UE to measure all CSI-RSs of candidate cells before the cell switch may cause excessive measurement overhead. The present disclosure provides a solution in which a CSI-RS resource set associated with an SSB resource set may be preconfigured and dynamically activated or deactivated by the serving cell or based on UE-determined conditions. The UE may measure and report CSI-RS resources associated with the activated CSI-RS resource set according to a report configuration, thereby enabling CSI-RS-based fine beam measurement before the LTM cell switch. This approach may reduce measurement overhead, prevent data rate degradation during cell switching, and improve overall mobility performance.

[0267] FIG. 7 is a flowchart illustrating a method / process 700 performed by a BS for configuring CSI-RS measurement reporting for LTM, according to an example implementation of the present disclosure. In the action 702, the process 700 may start by transmitting, to a UE via a serving cell, an LTM measurement configuration including an SSB resource set and a CSI-RS resource set associated with the SSB resource set. In the action 704, the process 700 may transmit, to the UE via the serving cell, a report configuration associated with the SSB resource set. The UE may activate the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied. The UE may start to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set. The UE may transmit, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration. The process 700 may then end. The method illustrated in FIG. 7 is similar to that in FIG. 6, except that it is described from the perspective of the BS (instead of the UE).

[0268] FIG. 8 is a block diagram illustrating a node 800 for wireless communication, according to an example implementation of the present disclosure. As illustrated in FIG. 8, a node 800 may include a transceiver 820, a processor 828, a memory 834, one or more presentation components 838, and at least one antenna 836. The node 800 may also include a radio frequency (RF) spectrum band module, a BS communications module, a network communications module, and a system communications management module, Input / Output (I / O) ports, I / O components, and a power supply (not illustrated in FIG. 8).

[0269] Each of the components may directly or indirectly communicate with each other over one or more buses 840. The node 800 may be a UE or a BS that performs various functions disclosed with reference to FIGS. 1 through 7.

[0270] The transceiver 820 has a transmitter 822 (e.g., transmitting / transmission circuitry) and a receiver 824 (e.g., receiving / reception circuitry) and may be configured to transmit and / or receive time and / or frequency resource partitioning information. The transceiver 820 may be configured to transmit in different types of subframes and slots including, but not limited to, usable, non-usable, and flexibly usable subframes and slot formats. The transceiver 820 may be configured to receive data and control channels.

[0271] The node 800 may include a variety of computer-readable media. Computer-readable media may be any available media that may be accessed by the node 800 and include volatile (and / or non-volatile) media and removable (and / or non-removable) media.

[0272] The computer-readable media may include computer-storage media and communication media. Computer-storage media may include both volatile (and / or non-volatile media), and removable (and / or non-removable) media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, AI / ML module(s), or data.

[0273] Computer-storage media may include RAM, ROM, EPROM, EEPROM, flash memory (or other memory technology), CD-ROM, Digital Versatile Disks (DVD) (or other optical disk storage), magnetic cassettes, magnetic tape, magnetic disk storage (or other magnetic storage devices), etc. Computer-storage media may not include a propagated data signal. Communication media may typically embody computer-readable instructions (e.g., computer-readable instructions related to AI module(s) and / or the ML module(s)), data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanisms and include any information delivery media.

[0274] The term “modulated data signal” may mean a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. Communication media may include wired media, such as a wired network or direct-wired connection, and wireless media, such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above listed components should also be included within the scope of computer-readable media.

[0275] The memory 834 may include computer-storage media in the form of volatile and / or non-volatile memory. The memory 834 may be removable, non-removable, or a combination thereof. Example memory may include solid-state memory, hard drives, optical-disc drives, etc. As illustrated in FIG. 8, the memory 834 may store a computer-readable and / or computer-executable instructions 832 (e.g., software codes) that are configured to, when executed, cause the processor 828 to perform various functions disclosed herein, for example, with reference to FIGS. 1 through 7. Alternatively, the instructions 832 may not be directly executable by the processor 828 but may be configured to cause the node 800 (e.g., when compiled and executed) to perform various functions disclosed herein.

[0276] The processor 828 (e.g., having processing circuitry) may include an intelligent hardware device, e.g., a Central Processing Unit (CPU), a microcontroller, an ASIC, etc. The processor 828 may include memory. The processor 828 may process the data 830 and the instructions 832 received from the memory 834, and information transmitted and received via the transceiver 820, the baseband communications module, and / or the network communications module. The processor 828 may also process information to send to the transceiver 820 for transmission via the antenna 836 to the network communications module for transmission to a CN.

[0277] One or more presentation components 838 may present data indications to a person or another device. Examples of presentation components 838 may include a display device, a speaker, a printing component, a vibrating component, etc.

[0278] In view of the present disclosure, it is obvious that various techniques may be used for implementing the disclosed concepts without departing from the scope of those concepts. Moreover, while the concepts have been disclosed with specific reference to certain implementations, a person of ordinary skill in the art may recognize that changes may be made in form and detail without departing from the scope of those concepts. As such, the disclosed implementations are to be considered in all respects as illustrative and not restrictive. It should also be understood that the present disclosure is not limited to the particular implementations disclosed and many rearrangements, modifications, and substitutions are possible without departing from the scope of the present disclosure.

Claims

1. A User Equipment (UE) for performing Channel State Information Reference Signal (CSI-RS) measurement reporting for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM), the UE comprising: 　　　　at least one processor; and 　　　　at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to: 　　　　　　　　receive, from a serving cell, an LTM measurement configuration comprising a Synchronization Signal Block (SSB) resource set and a CSI-RS resource set associated with the SSB resource set; 　　　　　　　　receive, from the serving cell, a report configuration associated with the SSB resource set; 　　　　　　　　activate the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied; 　　　　　　　　start to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set; and 　　　　　　　　transmit, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.

2. The UE of claim 1, wherein the specific condition comprises at least one of: 　　　　a first measured SSB quality of the serving cell being lower than a first threshold; 　　　　a second measured SSB quality of a candidate cell being greater than a second threshold; and 　　　　the second measured SSB quality of the candidate cell being greater than the first measured SSB quality of the serving cell by at least an offset.

3. The UE of claim 1, wherein: 　　　　the dynamic indication comprises a Medium Access Control (MAC) Control Element (CE) or Downlink Control Information (DCI) that indicates the CSI-RS resource set, and 　　　　the MAC CE comprises an LTM Cell Switch Command (CSC) MAC CE.

4. The UE of claim 1, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: 　　　　deactivate the CSI-RS resource set for LTM measurement in response to determining that at least one of the following conditions is satisfied: 　　　　　　　　reception of a deactivation indication from the serving cell; 　　　　　　　　expiration of a timer started upon activation of the CSI-RS resource set; and 　　　　　　　　the specific condition no longer being satisfied; and 　　　　stop measuring the CSI-RS resources associated with the CSI-RS resource set in response to deactivating the CSI-RS resource set.

5. The UE of claim 1, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: 　　　　receive, from the serving cell, an indicator indicating a reporting method selected from full SSB reporting, partial SSB reporting, and no SSB reporting, wherein: 　　　　　　　　in a case that the reporting method is full SSB reporting, the measurement report comprises a first number of measured SSBs and a measurement result of the activated CSI-RS resource set, 　　　　　　　　in a case that the reporting method is partial SSB reporting, the measurement report comprises a second number of measured SSBs and the measurement result of the activated CSI-RS resource set, 　　　　　　　　in a case that the reporting method is no SSB reporting, the measurement report comprises the measurement result of the activated CSI-RS resource set without measured SSBs, and 　　　　　　　　the first number is greater than the second number.

6. The UE of claim 5, wherein: 　　　　the indicator indicating the reporting method is included in the report configuration or the dynamic indication, and 　　　　the report configuration is received via Radio Resource Control (RRC) signaling.

7. The UE of claim 1, wherein the measurement report is transmitted via a Medium Access Control (MAC) Control Element (CE) comprising: 　　　　a report configuration identifier (ID) identifying the report configuration; 　　　　a CSI resource set ID identifying the CSI-RS resource set; 　　　　a field indicating whether absolute values or differential values are used in the measurement report; 　　　　a CSI-RS resource identifier (CRI); and 　　　　a measured quality value associated with the CRI.

8. The UE of claim 1, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: 　　　　receive, from the serving cell, an LTM Cell Switch Command (CSC) Medium Access Control (MAC) Control Element (CE) indicating the target cell; and 　　　　perform the LTM operation to switch from the serving cell to the target cell based on the LTM CSC MAC CE, wherein: 　　　　transmitting the measurement report comprises transmitting the measurement report to the target cell upon switching to the target cell.

9. The UE of claim 1, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: 　　　　perform the LTM operation to switch from the serving cell to the target cell, wherein: 　　　　the UE measures the CSI-RS resources associated with the CSI-RS resource set before performing the LTM operation, and 　　　　the LTM operation is a conditional LTM operation or is triggered by an LTM Cell Switch Command (CSC) Medium Access Control (MAC) Control Element (CE).

10. A Base Station (BS) for configuring Channel State Information Reference Signal (CSI-RS) measurement reporting for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM), the BS comprising: 　　　　at least one processor; and 　　　　at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the BS to: 　　　　　　　　transmit, to a User Equipment (UE) via a serving cell, an LTM measurement configuration comprising a Synchronization Signal Block (SSB) resource set and a CSI-RS resource set associated with the SSB resource set; and 　　　　　　　　transmit, to the UE via the serving cell, a report configuration associated with the SSB resource set, wherein: 　　　　the UE activates the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied, 　　　　the UE starts to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set, and 　　　　the UE transmits, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.

11. The BS of claim 10, wherein the specific condition comprises at least one of: 　　　　a first measured SSB quality of the serving cell being lower than a first threshold; 　　　　a second measured SSB quality of a candidate cell being greater than a second threshold; and 　　　　the second measured SSB quality of the candidate cell being greater than the first measured SSB quality of the serving cell by at least an offset.

12. The BS of claim 10, wherein: 　　　　the dynamic indication comprises a Medium Access Control (MAC) Control Element (CE) or Downlink Control Information (DCI) that indicates the CSI-RS resource set, and 　　　　the MAC CE comprises an LTM Cell Switch Command (CSC) MAC CE.

13. The BS of claim 10, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the BS to: 　　　　transmit, to the UE via the serving cell, an indicator indicating a reporting method selected from full SSB reporting, partial SSB reporting, and no SSB reporting, wherein: 　　　　　　　　in a case that the reporting method is full SSB reporting, the measurement report comprises a first number of measured SSBs and a measurement result of the activated CSI-RS resource set, 　　　　　　　　in a case that the reporting method is partial SSB reporting, the measurement report comprises a second number of measured SSBs and the measurement result of the activated CSI-RS resource set, 　　　　　　　　in a case that the reporting method is no SSB reporting, the measurement report comprises the measurement result of the activated CSI-RS resource set without measured SSBs, and 　　　　　　　　the first number is greater than the second number.

14. The BS of claim 13, wherein: 　　　　the indicator indicating the reporting method is included in the report configuration or the dynamic indication, and 　　　　the report configuration is received via Radio Resource Control (RRC) signaling.

15. A method performed by a User Equipment (UE) for performing Channel State Information Reference Signal (CSI-RS) measurement reporting for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM), the method comprising: 　　　　receiving, from a serving cell, an LTM measurement configuration comprising a Synchronization Signal Block (SSB) resource set and a CSI-RS resource set associated with the SSB resource set; 　　　　receiving, from the serving cell, a report configuration associated with the SSB resource set; 　　　　activating the CSI-RS resource set for LTM measurement in response to receiving a dynamic indication from the serving cell or in response to determining that a specific condition is satisfied; 　　　　starting to measure CSI-RS resources associated with the CSI-RS resource set in response to activating the CSI-RS resource set; and 　　　　transmitting, to the serving cell or a target cell of an LTM operation, a measurement report associated with the activated CSI-RS resource set based on the report configuration.

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