Method and apparatus for utilizing l1 triggering events in a wireless communication system

Abstract

A User Equipment (UE) for utilizing Layer-1 (L1) triggering events is provided. The UE receives a radio resource control (RRC) configuration of L1 triggering event(s) associated with candidate cell(s), each L1 triggering event configured with a reference signal type, a reference signal quality and a time-to-trigger (TTT) value and associated with one of the candidate cell(s); obtain an L1 measurement result by performing a physical layer measurement on the candidate cell(s); determine, based on the L1 measurement result, whether at least one L1 triggering event is satisfied; and in response to determining that the at least one L1 triggering events is satisfied, initiate one or more of multiple actions with a target candidate cell. The multiple actions are configured in the RRC configuration to be associated with the L1 triggering event(s). In addition, a method and a Base Station (BS) are also provided.

Description

METHOD AND APPARATUS FOR UTILIZING L1 TRIGGERING EVENTS IN A WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure is related to wireless communication and, more specifically, to a User Equipment (UE), Base Station (BS), and method for utilizing Layer-1 (L1) triggering events in a wireless communication system.

[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 a beam management procedure.Summery of Invention

[0003] The present disclosure is directed to a User Equipment (UE), a Base Station (BS), and a method for utilizing Layer-1 (L1) triggering events in a wireless communication system.

[0004] According to a first aspect of the present disclosure, a UE for utilizing L1 triggering events in a wireless communication system is provided. The UE includes: 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. When executed by the at least one processor, the one or more instructions cause the UE to: receive, from a BS, a radio resource control (RRC) configuration of one or more L1 triggering events associated with one or more candidate cells. Each of the one or more L1 triggering events is configured with a reference signal type, a reference signal quality, and a time-to-trigger (TTT) value, and is associated with one of the one or more candidate cells. When executed by the at least one processor, the one or more instructions further cause the UE to: obtain an L1 measurement result by performing a physical layer measurement on the one or more candidate cells; determine, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied; and in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiate one or more of multiple actions with a target candidate cell among the one or more candidate cells. The one or more actions are configured in the RRC configuration to be associated with the at least one of the one or more L1 triggering events. The multiple actions include: performing an early synchronization with the target candidate cell; performing a Layer-1 / Layer-2 triggered mobility (LTM) cell switch procedure with the target candidate cell; and transmitting the L1 measurement result to a serving random access network (RAN).

[0005] In an implementation of the first aspect, obtaining the L1 measurement result by performing the physical layer measurement includes: determining a beam for performing the physical layer measurement. The beam includes one of: a current transmission configuration indicator (TCI) beam associated with a serving cell; a best beam determined based on a downlink reference signal received power (DL-RSRP); a best beam, among one or more activated TCI-state beams, determined based on the DL-RSRP; and a beam configured by a RAN.

[0006] In another implementation of the first aspect, the multiple actions further include: performing or halting an L3 measurement; performing or halting an L3 measurement reporting; and performing a conditional mobility operation. The conditional mobility operation includes at least one of a conditional handover, a conditional Primary Secondary Cell (PSCell) addition, and a conditional PSCell change.

[0007] In another implementation of the first aspect, in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiating the one or more actions with the target candidate cell among the one or more candidate cells includes: determining, based on the L1 measurement result, whether an entering condition or a leaving condition is satisfied; in response to determining that the entering condition has been continuously satisfied for a first duration indicated by a first TTT value associated with the satisfied entering condition, determining to initiate the one or more actions; and in response to determining that the leaving condition has been continuously satisfied for a second duration indicated by a second TTT value associated with the satisfied leaving condition, determining to halt the one or more actions. The first TTT and the second TTT are configured in the RRC configuration.

[0008] In another implementation 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 BS, a reference configuration including a default configuration for the one or more L1 triggering events and the associated one or more candidate cells; receive, from the BS, a delta configuration associated with one of the one or more L1 triggering events or with one of the one or more candidate cells; and initiate the one or more actions associated with the at least one of the one or more L1 triggering events satisfied on the target candidate cell by combining the reference configuration and the delta configuration.

[0009] In another implementation of the first aspect, the one or more L1 triggering events include one or more of the following: a first signal quality of a beam associated with a serving cell becoming better than a first absolute threshold; the first signal quality of the beam associated with the serving cell becoming worse than a second absolute threshold; a second signal quality of a beam associated with a candidate cell becoming better than a third signal quality of a beam associated with a primary cell (PCell), a PSCell, or the serving cell by a first offset; the second signal quality of the beam associated with the candidate cell becoming better than a third absolute threshold; the first signal quality of the beam associated with the serving cell becoming worse than a fourth absolute threshold and the second signal quality of the beam associated with the candidate cell becoming better than a fifth absolute threshold; and a fourth signal quality of a beam associated with a neighboring cell becoming better than a fifth signal quality of a beam associated with a secondary cell (SCell).

[0010] In another implementation 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 BS, a medium access control (MAC) control element (CE) or downlink control information (DCI) including an indication to activate at least one of the one or more L1 triggering events.

[0011] According to a second aspect of the present disclosure, a BS for utilizing L1 triggering events in a wireless communication system is provided. The BS includes: 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. When executed by the at least one processor, the one or more instructions cause the BS to: transmit, to a UE, an RRC configuration of one or more L1 triggering events associated with one or more candidate cells. Each of the one or more L1 triggering events is configured with a reference signal type, a reference signal quality, and a TTT value, and is associated with one of the one or more candidate cells. The RRC configuration causes the UE to: obtain an L1 measurement result by performing a physical layer measurement on the one or more candidate cells; determine, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied; and in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiate one or more of multiple actions with a target candidate cell among the one or more candidate cells. The one or more actions are configured in the RRC configuration to be associated with the at least one of the one or more L1 triggering events. The multiple actions include: performing an early synchronization with the target candidate cell; performing an LTM cell switch procedure with the target candidate cell; and transmitting the L1 measurement result to a serving RAN.

[0012] In an implementation of the second aspect, the RRC configuration further causes the UE to: determine a beam for performing the physical layer measurement. The beam includes one of: a current TCI beam associated with a serving cell; a best beam determined based on a DL-RSRP; a best beam, among one or more activated TCI-state beams, determined based on the DL-RSRP; and a beam configured by a RAN.

[0013] In another implementation of the second aspect, the multiple actions further include: performing or halting an L3 measurement; performing or halting an L3 measurement reporting; and performing a conditional mobility operation. The conditional mobility operation includes at least one of a conditional handover, a conditional PSCell addition, and a conditional PSCell change.

[0014] In another implementation of the second aspect, the RRC configuration includes a first TTT value and a second TTT value, and further causes the UE to: determine, based on the L1 measurement result, whether an entering condition or a leaving condition is satisfied; in response to determining that the entering condition has been continuously satisfied for a first duration indicated by the first TTT value associated with the satisfied entering condition, determine to initiate the one or more actions; and in response to determining that the leaving condition has been continuously satisfied for a second duration indicated by the second TTT value associated with the satisfied leaving condition, determine to halt the one or more actions.

[0015] In another implementation 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, a reference configuration including a default configuration for the one or more L1 triggering events and the associated one or more candidate cells; and transmit, to the UE, a delta configuration associated with one of the one or more L1 triggering events or with one of the one or more candidate cells. The RRC configuration, the reference configuration, and the delta configuration cause the UE to: initiate the one or more actions associated with the at least one of the one or more L1 triggering events satisfied on the target candidate cell by combining the reference configuration and the delta configuration.

[0016] In another implementation of the second aspect, the one or more L1 triggering events include one or more of the following: a first signal quality of a beam associated with a serving cell becoming better than a first absolute threshold; the first signal quality of the beam associated with the serving cell becoming worse than a second absolute threshold; a second signal quality of a beam associated with a candidate cell becoming better than a third signal quality of a beam associated with a PCell, a PSCell, or the serving cell by a first offset; the second signal quality of the beam associated with the candidate cell becoming better than a third absolute threshold; the first signal quality of the beam associated with the serving cell becoming worse than a fourth absolute threshold and the second signal quality of the beam associated with the candidate cell becoming better than a fifth absolute threshold; and a fourth signal quality of a beam associated with a neighboring cell becoming better than a fifth signal quality of a beam associated with a SCell.

[0017] In another implementation 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, a MAC CE or DCI including an indication to activate at least one of the one or more L1 triggering events.

[0018] According to a third aspect of the present disclosure, a method performed by a UE for utilizing L1 triggering events in a wireless communication system is provided. The method includes: receiving, from a BS, an RRC configuration of one or more L1 triggering events associated with one or more candidate cells. Each of the one or more L1 triggering events is configured with a reference signal type, a reference signal quality, and a TTT value, and is associated with one of the one or more candidate cells. The method also includes: obtaining an L1 measurement result by performing a physical layer measurement on the one or more candidate cells; determining, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied; and in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiating one or more of multiple actions with a target candidate cell among the one or more candidate cells. The one or more actions are configured in the RRC configuration to be associated with the at least one of the one or more L1 triggering events. The multiple actions include: performing an early synchronization with the target candidate cell; performing an LTM cell switch procedure with the target candidate cell; and transmitting the L1 measurement result to a serving RAN.

[0019] Aspects of the present disclosure are best understood from the following detailed disclosure and the corresponding figures. Various features are not drawn to scale and dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

[0020] FIG. 1 is a diagram illustrating an association of Layer-1 (L1) event configurations and Layer-1 (L1) / Layer-2 (L2) Triggered Mobility (LTM) candidates, according to an example implementation of the present disclosure.

[0021] FIG. 2 is a diagram illustrating a procedure performed by a user equipment (UE) with an LTM candidate, according to an example implementation of the present disclosure.

[0022] FIG. 3 is a diagram illustrating a signaling procedure of a two-stage activation of L1 event(s), according to an example implementation of the present disclosure.

[0023] FIG. 4 is a diagram illustrating trigger and leave conditions, according to an example implementation of the present disclosure.

[0024] FIG. 5 is a diagram illustrating a signaling procedure of an LTM serving cell switch (SCS) operation, according to an example implementation of the present disclosure.

[0025] FIG. 6 is a flowchart illustrating a method / process performed by a UE for utilizing L1 triggering events, according to an example implementation of the present disclosure.

[0026] FIG. 7 is a block diagram illustrating a node for wireless communication, according to an example implementation of the present disclosure.

[0027] Some of the abbreviations used in the present disclosure include: Abbreviation　　　　Full name 3GPP　　　　3rd Generation Partnership Project 5G　　　　5th Generation 5GC　　　　5G Core AMF　　　　Access and Mobility Management Function ARFCN　　　　Absolute Radio-Frequency Channel Number AS　　　　Access Stratum BS　　　　Base Station BWP　　　　Bandwidth Part CA　　　　Carrier Aggregation CAG　　　　Closed Access Group CN　　　　Core Network CU　　　　Central Unit DAPS　　　　Dual Active Protocol Stack DC　　　　Dual Connectivity DCI　　　　Downlink Control Information DL　　　　Downlink DU　　　　Distributed Unit E-UTRA(N)　　　　Evolved Universal Terrestrial Radio Access (Network) EN-DC　　　　E-UTRA NR Dual Connectivity EPC　　　　Evolved Packet Core FR　　　　Frequency Range IAB　　　　Integrated Access and Backhaul ID　　　　Identifier IE　　　　Information Element LAN　　　　Local Area Network LTE　　　　Long Term Evolution LTM　　　　Layer-1 (L1) / Layer-2 (L2) Triggered Mobility LTM SCS　　　　L1 / L2 Triggered Mobility Serving Cell Switch MAC　　　　Medium Access Control MAC CE　　　　MAC Control Element MCG　　　　Master Cell Group MIB　　　　Master Information Block MN　　　　Master Node MSG　　　　Message MT　　　　Mobile Termination NAS　　　　Non-Access Stratum NE-DC　　　　NR E-UTRA Dual Connectivity NES　　　　Network Energy Saving NPN　　　　Non-Public Network NR　　　　New Radio NR-U　　　　NR Unlicensed NW　　　　Network NSSAI　　　　Network Slice Selection Assistance Information PCell　　　　Primary Cell PCI　　　　Physical Cell Identity PDCCH　　　　Physical Downlink Control Channel PDSCH　　　　Physical Downlink Shared Channel PDU　　　　Protocol Data Unit PHY　　　　Physical (layer) PLMN　　　　Public Land Mobile Network PNI-NPN　　　　Public Network Integrated Non-Public Network PRACH　　　　Physical Random Access Channel PSCell　　　　Primary Secondary Cell PUCCH　　　　Physical Uplink Control Channel PUSCH　　　　Physical Uplink Shared Channel RA　　　　Random Access RAN　　　　Radio Access Network RAR　　　　Random Access Response RAT　　　　Random Access Technology RF　　　　Radio Frequency RNTI　　　　Radio Network Temporary Identifier RRC　　　　Radio Resource Control RS　　　　Reference Signal RSRP　　　　Reference Signal Received Power SCell　　　　Secondary Cell SCG　　　　Secondary Cell Group SI　　　　System Information SIB　　　　System Information Block SL　　　　Sidelink SN　　　　Secondary Node SNPN　　　　Stand-alone Non-Public Network SSB　　　　Synchronization Signal Block TS　　　　Technical Specification UE　　　　User Equipment UL　　　　Uplink V2X　　　　Vehicle-to-Everything WUS　　　　Wake-Up Signal

[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 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 executable instructions and perform the disclosed network function(s) or algorithm(s).

[0036] The microprocessors or general-purpose computers may include Application-Specific Integrated Circuits (ASICs), programmable logic arrays, and / or one or more Digital Signal Processor (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 includes but is not limited to Random Access Memory (RAM), Read Only Memory (ROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory, Compact Disc Read-Only Memory (CD-ROM), magnetic cassettes, magnetic tape, magnetic disk storage, 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) typically includes at least one base station (BS), at least one UE, and one or more optional network elements that provide connection within a network. The UE communicates with the network such as a Core Network (CN), an Evolved Packet Core (EPC) network, an Evolved Universal Terrestrial RAN (E-UTRAN), a 5G Core (5GC), or an internet via a RAN established by one or more BSs.

[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, or a Personal Digital Assistant (PDA) with wireless communication capability. The UE is configured to receive and transmit signals over an air interface to one or more cells in a RAN.

[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 LTE (eLTE) that is LTE connected to 5GC, NR (often referred to as 5G), 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, an 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 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.

[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 DL (and optionally 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) or Vehicle to Everything (V2X) services. Each cell may have overlapped coverage areas with other cells.

[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 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] It In some implementations, a UE may be configured with Layer-1 (L1) measurements with specific reference signal (RS) types (e.g., Synchronization Signal Block (SSB) and / or Channel State Information-Reference Signal (CSI-RS)). In some implementations, the UE may be further configured with “periodical reporting” or “event-triggered reporting” to transmit the L1 measurement results to the serving Radio Access Network (RAN).

[0053] In some implementations, the UE may be configured with one or more of Event A1-b to Event A6-b as the triggering event(s) to report the UE’s L1 measurement results.

[0054] Event A1-b: Beam of serving cell becomes better than an absolute threshold. It should be noted that Event A1-b may also be referred to as Event LTM1.

[0055] Event A2-b: Beam of serving cell becomes worse than an absolute threshold. It should be noted that Event A2-b may also be referred to as Event LTM2.

[0056] Event A3-b: Beam of candidate cell becomes a certain amount of offset better than a beam of a Primary Cell (PCell), a Primary Secondary Cell (PSCell), or a serving cell. It should be noted that Event A3-b may also be referred to as Event LTM3.

[0057] Event A4-b: Beam of candidate cell becomes better than an absolute threshold. It should be noted that Event A4-b may also be referred to as Event LTM4.

[0058] Event A5-b: Beam of serving cell becomes worse than an absolute threshold and beam of candidate cell becomes better than another absolute threshold. It should be noted that Event A5-b may also be referred to as Event LTM5.

[0059] Event A6-b: Beam of neighbor cell becomes a certain amount of offset better than a Secondary Cell (SCell).

[0060] In some implementations, the “beam of serving cell” described in Event A1-b to Event A6-b may include one or more of the following: 　　　　- The serving beam (e.g., the beam corresponding to the Transmission Configuration Indicator (TCI) state indicated by the latest Downlink Control Information (DCI)); 　　　　- The best beam measured in the serving cell (e.g., the beam corresponding to the largest reference signal received power (RSRP) value among the configured beams); 　　　　- The best activated beam measured in the serving cell (e.g., the beam corresponding to the largest RSRP value among the activated beams); and / or 　　　　- A beam which is indicated by the serving cell.

[0061] In some implementations, the L1 (measurement / report / triggering) Events may be implemented for Layer-1 / Layer-2 Triggered Mobility (LTM) purpose(s), such as: 　　　　- Action A: Select the candidate beam / cell to trigger early synchronization; 　　　　- Action B: Select the target beam / cell and trigger an LTM cell switch procedure; and / or 　　　　- Action C: Report L1 measurement results to the serving RAN.

[0062] In some implementations, the L1 (measurement / report / triggering) Events may also be used to trigger L3 (measurement / report / conditional) mobility procedures, such as: 　　　　- Action D: Trigger / leave a Layer-3 (L3) cell / beam quality report; and / or 　　　　- Action E: Trigger a conditional handover (CHO) procedure, conditional PSCell addition (CPA), conditional PSCell addition or change (CPAC), or Conditional PSCell change (CPC).

[0063] In some implementations, the L1 (e.g., measurement) event(s) may combine with one or more L3 report / triggering events to support the triggering / stop of Action D and / or Action E. Each action may be associated with one or more LTM candidates (e.g., LTM candidate cell(s)) and one or more L1 events. However, the L1 (measurement / report / triggering) events are not restricted to LTM operations.

[0064] In the present disclosure, several implementations are provided to enhance the cellular network / UE architecture when the L1 (measurement / report / triggering) events are introduced. In some implementations, designs for LTM operation enhancements are provided. In some implementations, designs for L3 measurement enhancements are provided.

[0065] Design#1 For LTM operation Enhancements

[0066] The mapping / association relationship of L1 (measurement / report / triggering) events and LTM candidates are described in advance, for the triggering events design of Action A / B / C for LTM operation enhancements. Specifically, there may be a many-to-many relationship between multiple L1 event configurations and multiple LTM candidates.

[0067] FIG. 1 is a diagram illustrating an association of L1 event configurations and LTM candidates, according to an example implementation of the present disclosure.

[0068] Referring to FIG. 1, a first L1 event configuration 111 may be associated with a first LTM candidate 121, a second LTM candidate 122, a third LTM candidate 123, and a fourth LTM candidate 124. A second L1 event configuration 112 may be associated with the first LTM candidate 121 and the fourth LTM candidate 124. A third L1 event configuration 113 may be associated with the third LTM candidate 123. A fourth L1 event configuration 114 may be associated with the third LTM candidate 123.

[0069] Design#2 For L3 Measurement Enhancements

[0070] In Design#2, parameters of L1 (measurement / report / triggering) events are described by referring to existing L3 (cell / beam) measurement / report configuration. In addition, the combinations and possible mutual impact of the L1 (measurement / report / triggering) events and L3 measurement / report configurations are also described.

[0071] Design#1 For LTM operation Enhancements (Continue)

[0072] In some implementations, the L1 (measurement / report / triggering) event and report may be implemented based on the LTM configuration and operation (e.g., the LTM-config IE and LTM operation defined in 3GPP TS 38.331 v18.2.0 and TS 38.321 v18.2.0).

[0073] LTM-CSI-ReportConfig

[0074] In some implementations, the L1 (measurement / report / triggering) events may be configured as part of LTM CSI report configuration (e.g., by referring to the LTM-CSI-ReportConfig IE defined in 3GPP TS 38.331 v18.2.0).

[0075] ltm-ReportConfigType

[0076] In some implementations, a new Event-Triggered IE may be configured as part of an LTM report configuration type. In some implementations, the serving RAN may choose an Event-Triggered IE with further associated one or more L1 measurement report events, as shown in Table 1 below. The serving RAN may configure one or more L1 report configurations, which can be either periodic / semi-persistent on Physical Uplink Control Channel (PUCCH) / aperiodic or event-triggered.

[0077] In some implementations, the serving RAN may configure multiple report type configurations to the UE. Therefore, the report type “Event-Triggered’ may be configured to the UE along with other report types such as “periodic” and / or “semiPersistentOnPUCCH” and / or “aperiodic”. For example, the ltm-ReportConfigType may be configured as “sequence” instead of “choice”, and more than one event can be configured jointly.

[0078] In some implementations, the UE may be configured with one or more L1 (measurement / report / triggering) events jointly in one L1 measurement report configuration. Therefore, further information may be provided to be associated with each event, such as one L1 triggering event is {enabled / disabled}, {allowed / not-allowed}, {configured / removed}. In some implementations, the UE may consider the L1 (measurement / report / triggering) events to be applicable (e.g., the event is applied to the evaluation for triggering a report) if the events are present in the Event-Triggered IE or if the events are present with value “enabled” in the Event-Triggered IE, as shown in Table 2 below. In some implementations, the UE may consider the L1 (measurement / reporting / triggering) events to be not applicable (e.g., the event is not applied to the evaluation for triggering a report) if the events are present with value “disabled” in the Event-Triggered IE, as shown in Table 2 below.

[0079] In some implementations, the L1 measurement report configuration may be an “optional” IE in the RRC configuration to the UE. In some implementations, the L1 measurement report configuration may be designed as a “Need M (maintain)” IE or a “Need R (Release)” IE in the RRC configuration to the UE.

[0080] Reference Signal Type and Quantity

[0081] In some implementations, the reference signal type (e.g., rsType) may be configured with CSI-RS and / or SSB. It should be noted that the CSI-RS resource may be associated with a Tracking Reference Signal (TRS).

[0082] In some implementations, the quantity of the L1 measurement / report / triggering event (e.g., rsQuantity) may be implemented on configured quantity, such as a DL-RSRP, a DL-RSRQ, and / or DL-SINR. In some implementations, the rsType / rsQuantity may be configured in the LTM reference configuration as a default setting for an L1 measurement / report / triggering event. In some implementations, an LTM candidate / L1 (measurement / report / triggering) event may be further associated with specific rsType / rsQuantity for the UE to implement measurement / evaluation.

[0083] Time-To-Trigger (TTT) Design for L1 (measurement / report / triggering) event

[0084] The TimeToTrigger IE may specify the value range used for a time-to-trigger parameter, which concerns the time during which specific criteria for the event needs to be met in order to trigger Action A / B / C / D / E described above. As shown in Table 3 below, in the TimeToTrigger IE, a value of “ms0” may correspond to 0 milliseconds (ms), a value of “ms40” may correspond to 40 ms, and so on.

[0085] In some implementations, an L1 (measurement / report / triggering) event may be further configured with a TTT (e.g., Tt). Based on the configuration of Tt, the UE may trigger (any combinations of) Action A / B / C / D / E after the UE detects / observes an L1 (measurement / report / triggering) event (with / without one or more combined conditional (L3) events) is consistently / continuously fulfilled longer than a time period Tt. For example, the UE may set a TTT timer, where the initial value of the TTT timer is equivalent to Tt, upon the UE detecting / observing an L1 (measurement / report / triggering) event being fulfilled. Then, the UE may not initiate Action A / B / C / D / E immediately unless the condition of the L1 (measurement / report / triggering) event (which activates the Ttcounting activity) is still fulfilled during the time period that the TTT timer is still running. Additionally, the UE may initiate / start Action A / B / C / D / E upon or after the TTT timer expires and the L1 (measurement / report / triggering) event is still fulfilled. In other words, the TTT timer may be stopped / released while the L1 (measurement / report / triggering) event which triggers the TTT timer running activity becomes not valid / non-fulfilled. Therefore, the L1 (measurement / report / triggering) event may become invalid, and the UE may not take any action. In some implementations, the UE may implement the configured action(s) associated with the L1 event immediately without the TTT counting activity. In some implementations, the value of Ttmay be configurable, and the value of Ttmay be configured to zero.

[0086] In some implementations, the TTT timer counting mechanism may be associated with the joint combinations of one or more L1 events and one or more L3 events. In such a case, a TTT configuration may be configured to be associated with the combinations of the conditional L1 / L3 events. Then, the TTT timer may be started upon or after all of the combined conditional events are fulfilled. Additionally, the TTT timer may be stopped / reset upon any configured L1 / L3 event in the combinations is not fulfilled.

[0087] In some implementations, the TTT value may be provided in the reference configuration or in the ltm-Config / LTM-Config IE (e.g., the IE configuring all the LTM-related configurations) as one default setting to all the LTM candidates / L1 (measurement / report / triggering) event configuration (e.g., if the LTM candidate / L1 (measurement / report / triggering) event is not configured with a TTT value). In some implementations, if an L1 (measurement / reporting / triggering) event is configured with a specific TTT value, the UE may ignore the default TTT value.

[0088] In some implementations, the proposed mechanisms about the L1 event(s) evaluation / implementations may be included as part of the ltm-ReferenceConfiguration IE in the 3GPP New Radio protocols. However, in some implementations, the configurations related to L1 event evaluation / implementations may be implemented / applied earlier than the LTM SCS operation (e.g., which may be triggered by receiving an LTM SCS MAC CE reception or by conditional LTM operation described in the present disclosure). In some implementations, another specific reference configuration for the proposed L1 events evaluations / conditional LTM evaluation (e.g., which may be defined by the Conditional-ReferenceConfiguration IE) may be configured separately from the (e.g., conventional) the ltm-ReferenceConfiguration IE. Additionally, the UE may evaluate each LTM candidate and L1 event evaluations based on the Conditional-ReferenceConfiguration IE. Thus, the Conditional-ReferenceConfiguration IE may be applied before the LTM SCS operation is triggered.

[0089] In some implementations, the UE may stop / interrupt the evaluations of conditional LTM operation / L1 event(s) evaluation upon or after the (e.g., conditional) LTM operation is triggered by the UE. However, in some implementations, the UE may still keep / continue the evaluations of conditional LTM operation / L1 event(s) evaluation upon or after the (e.g., conditional) LTM operation is triggered by the UE.

[0090] In some implementations, an LTM candidate may be configured with a specific TTT value for the L1 (measurement / report / triggering) event associated with the LTM candidate.

[0091] In some implementations, an LTM candidate may be configured with evaluation criteria / parameters (e.g., Quantity configuration, such as threshold and / or TTT timer) and a specific L1 event may also be configured with another evaluation criteria / parameter (e.g., Quantity configuration, such as threshold and / or TTT timer). In such a condition, several approaches may be instructed by the serving RAN.

[0092] In some implementations, the evaluation criteria / parameters associated with the L1 event (e.g., e.g., the configurationEventL1 IE) may always have higher priority than the evaluation criteria / parameters associated with the LTM candidate (e.g., the configurationCandidate IE). Therefore, the UE may perform L1 event evaluation based on the configurationEventL1 IE (e.g., and ignore the configurationCandidate IE).

[0093] In some implementations, the evaluation criteria / parameters associated with the LTM candidate (e.g., the configurationCandidate IE) may always have higher priority than the evaluation criteria / parameters associated with the L1 event (e.g., the configurationEventL1 IE). Therefore, the UE may perform L1 event evaluation based on the configurationCandidate IE (e.g., and ignore the configurationEventL1 IE).

[0094] In some implementations, the UE may determine the evaluation criteria / parameters of the LTM candidate associated with an L1 Event by jointly combining the configured configurationEventL1 IE and configurationCandidate IE. Additionally, when a parameter (e.g., TTT timer) is present in both the configurationEventL1 IE and configurationCandidate IE, the UE may apply one of the priority rules described above.

[0095] In some implementations, an L1 (measurement / report / triggering) event may be configured with a specific TTT value.

[0096] In some implementations, a common Ttvalue may be configured by a UE to be associated with one or more L1 (measurement / report / triggering) events. In some implementations, “common” may mean that Ttmay be shared by multiple UEs (e.g., the Ttconfiguration may be provided by broadcasting system information or on-demand SI procedure). In some implementations, “common” may mean Ttmay be shared by multiple L1 (measurement / report / triggering) events in a single UE (e.g., the Ttconfiguration may be provided by UE-specific control signaling, such as RRC signaling / MAC CE / DCI).

[0097] In some implementations, the UE may evaluate / measure one or more L1 (measurement / report / triggering) events jointly / simultaneously. In some examples, this design may be applied to each LTM candidate separately. In other words, each LTM candidate may be configured with multiple L1 measurement / report / triggering events, and each LTM candidate may be considered independently. In some examples, this design may be implemented across all (or a subset of) the LTM candidates.

[0098] In some implementations, the UE may stop evaluating / measuring any L1 (measurement / report / triggering) event while there is already a running / active TTT timer (associated with one or more fulfilled L1 (measurement / report / triggering) events) or upon / while a TTT timer (associated with one L1 measurement / report / triggering event) is started by the UE. In some implementations, the UE may still be able to evaluate / measure / detect other L1 (measurement / report / triggering) events even though there is already a running / active TTT timer running. Therefore, the UE may be able to start / count more than one TTT timer jointly / simultaneously. The UE may need to maintain multiple active TTT timers simultaneously in the time domain. In some examples, this design may be applied to each LTM candidate separately. In other words, each LTM candidate may be configured with multiple L1 measurement / report / triggering events, and each LTM candidate may be considered independently. In some examples, this design may be implemented across all (or a subset of) the LTM candidates.

[0099] In some implementations, the UE may stop evaluating / measuring any L1 (measurement / report / triggering) event upon / while the UE already implements Action A / B / C / D / E due to the TTT timer of one L1 (measurement / report / triggering) event expiring. In some implementations, the running TTT timer of the L1 (measurement / report / triggering) events may also be stopped / released upon or after the UE implements an Action A / B / C triggered by an L1 (measurement / report / triggering) event. In some examples, this design may be applied to each LTM candidate separately. In other words, each LTM candidate may be configured with multiple L1 measurement / report / triggering events, and each LTM candidate may be considered independently. In some examples, this design may be implemented across all (or a subset of) the LTM candidates.

[0100] In some implementations, the UE may initiate and count multiple TTT timers independently. However, if a running TTT timer expires and the UE also triggers the actions, the other running TTT timers may be stopped / released by the UE.

[0101] In some implementations, one common Time-To-Trigger value may be defined for one or more L1 (measurement / report / triggering) events.

[0102] In some implementations, the TTT timer may be activated / counted / stopped / released by the MAC entity. In such a case, the RRC entity may need to configure the LTM candidates / L1 events / TTT values to the MAC entity. Additionally, upon the TTT timer expiring, the MAC entity may also need to inform the RRC entity that an L1 (measurement / report / triggering) event is fulfilled (and the TTT timer has expired). After receiving the information from the MAC entity, the RRC entity may start Action A / B / C after receiving the indication from the MAC entity. In some implementations, the MAC entity may start Action A / B / C after deciding an L1 event (associated with one LTM candidate) is fulfilled (and the TTT timer has expired).

[0103] In some implementations, the TTT timer may be activated / counted / stopped / released by the RRC entity.

[0104] TimeToTrigger and Action A / B / C / D / E

[0105] In some implementations, the TTT timer values configured for each different action (e.g., Action A / B / C) may be different.

[0106] FIG. 2 is a diagram illustrating a procedure performed by a UE with an LTM candidate, according to an example implementation of the present disclosure.

[0107] Referring to FIG. 2, in some implementations, at time point 21, a UE may start performing Action A associated with one LTM candidate immediately while one L1 (measurement / report / triggering) event is fulfilled. Additionally, a TTT timer associated with the L1 (measurement / report / triggering) event and the same LTM candidate may also be triggered to be counted to zero at time point 21 while the L1 (measurement / report / triggering) event is fulfilled. At time point 22, the UE may start performing Action B upon, while, or after the TTT timer expires.

[0108] It should be noted that, other L1 / L3 event(s) (or combined L1 / L3 event) for other actions (e.g., not limited to Action A and B, as described in FIG, 2) may also be applied to the mechanism described in FIG. 2.

[0109] In some implementations, the procedure as illustrated in FIG. 2 may be associated with one specific LTM candidate. Additionally, the UE may maintain multiple procedures, where each procedure, similar to that illustrated in FIG. 2, may be associated with one specific LTM candidate, for (conditional) LTM operation.

[0110] In some implementations, the UE may trigger an LTM cell switch operation associated with one LTM candidate, and there may also be some running TTT timers associated with other LTM candidates. In such a case, the UE may terminate / release / stop / suspend the remaining procedures (e.g., for which the TTT timers are still running) upon or after the UE triggers an LTM cell switch operation associated with one LTM candidate. In some implementations, the UE may still evaluate / implement L1 (measurement / report / triggering) events even after an action is already implemented / triggered (e.g., Action A / B / C). The UE may stop / release / terminate all the measurement / evaluation of L1 (measurement / report / triggering) events while, upon, or after an LTM cell switch operation is terminated successfully at the UE side (e.g., by referring to the complete condition of LTM operation).

[0111] L1 (measurement / report / triggering) event evaluation triggered by dedicated signaling

[0112] In some implementations, a UE may be configured / instructed to start / activate the L1 (measurement / report / triggering) event based on UE-specific control signaling.

[0113] In some implementations, the UE may be pre-configured by a UE-specific RRC signaling (e.g., RRCReconfiguration / RRCResume / RRCSetup message) with one or more L1 (measurement / report / triggering) events associated with one or more LTM candidates. In some implementations, the UE may be enabled / authorized to start the evaluation procedure of one or more L1 (measurement / report / triggering) events after receiving the RRC signaling.

[0114] In some implementations, the UE may receive a (conditional) LTM cell switch command (CSC) MAC CE, which activates / triggers / enables / configures the UE to start the evaluation / measurement of one or more L1 (measurement / report / triggering) events. In such a case, the LTM CSC MAC CE may include further information to activate an L1 (measurement / report / triggering) event evaluation. In some implementations, the UE may also receive an IE (e.g., via the pre-configuration via RRC signaling) which allows / enables the UE to start the evaluation / measurement of one or more L1 (measurement / report / triggering) event(s) upon or after receiving the LTM CSC MAC CE from the serving RAN. In some implementations, the proposed mechanism may also be applicable to the MAC CE which activates the TCI states of one LTM candidate.

[0115] In some implementations, the UE may receive DCI, which instructs the UE to implement an early Timing Advance (TA) acquisition procedure. Then, after receiving the DCI, the UE may also be authorized / enabled to start the evaluation / measurement of one or more L1 (measurement / report / triggering) events to initiate a random access procedure with one LTM candidate for one specific action (e.g., Action B). In such a case, the DCI may further include information (e.g., one or more index(-es) associated with L1 (measurement / report / triggering) event) to authorize / enable the UE to start the evaluation procedure. In some implementations, the UE may also receive an IE (e.g., via the pre-configuration via RRC signaling) which allows / enables the UE to start the evaluation / measurement of one or more L1 (measurement / report / triggering) event(s) upon or after receiving the DCI (e.g., for UE TA acquisition) from the serving RAN.

[0116] In some implementations, different LTM candidates may be configured with different activation rules / configurations, and these rules / configurations may be applied to the L1 (measurement / report / triggering) events associated with the LTM candidate.

[0117] Evaluation / Implementation entity (e.g., MAC entity)

[0118] In some implementations, the MAC entity of a UE may be configured by the RRC entity of the UE with one or more L1 (measurement / report / triggering) events.

[0119] In some implementations, each MAC entity (e.g., MAC entity associated with master cell group (MCG) / master node and / or MAC entity associated with secondary cell group (SCG) / secondary node) may be enabled / allowed to be independently configured with one or more L1 (measurement / report / triggering) events. In some implementations, only the MAC entity of the MCG may be configured with L1 (measurement / report / triggering) events.

[0120] In some implementations, the L1 (measurement / report / triggering) events associated with MCG may be configured by the serving RAN via Signaling Radio Bearer (SRB) 1 / SRB 3. The L1 (measurement / report / triggering) events associated with SCG may be configured by the serving RAN via SRB1 / SRB3.

[0121] In some implementations, the MAC entity associated with MCG / SCG may evaluate and trigger Action A / B / C independently (e.g., based on the Time-To-Trigger Timer counting activity). Therefore, Action A / B / C associated with MCG / SCG may be triggered / implemented jointly (e.g., with independent configurations) in the time domain.

[0122] In some implementations, the L1 (measurement / report / triggering) events may be allowed to be configured only with MCG / SCG. In some implementations, if a UE is storing / maintaining one or more L1 (measurement / report / triggering) events for one cell group (e.g., the MCG or SCG), upon receiving an RRC message configuring the L1 (measurement / report / triggering) event for the other cell group (e.g., the SCG or MCG), the UE may perform one or more of the following: 　　　　1) releasing the stored L1 (measurement / report / triggering) events for the cell group (e.g., the MCG or SCG) and store the L1 (measurement / report / triggering) events for the other cell group (e.g., the SCG or MCG); 　　　　2) ignoring the L1 (measurement / report / triggering) events configured in the RRC message; and / or 　　　　3) initiating the connection re-establishment procedure.

[0123] In some implementations, only one cell group may be capable of implementing Action A / B / C based on a given L1 (measurement / report / triggering) event in the time domain. Therefore, while one MAC entity (e.g., MAC entity associated with MCG or SCG) starts Action A / B / C based on an L1 (measurement / report / triggering) event, the UE may stop / suspend / release the evaluation / TTT timer counting activity of another MAC entity.

[0124] In some implementations, the serving RAN may also indicate / instruct the activated TCI state(s) associated with at least one LTM candidate / L1 (measurement / report / triggering) event in the control signaling and / or the specific (LTM SCS switch) MAC CE / DCI.

[0125] In some implementations, the MAC entity may inform the RRC entity of the UE side while one L1 (measurement / report / triggering) event is fulfilled, but the TTT Timer may be counting or be stopped in the MAC entity of the UE.

[0126] Beam association

[0127] In some implementations, the UE may implement an L1 measurement for an L1 (measurement / report / triggering) event based on current operating beams (e.g., SSB burst(s) / CSI-RS / TRS) associated with one LTM candidate cell / current serving cell (with further TCI state association with the SSB of the LTM candidate).

[0128] In some implementations, the UE may implement an L1 measurement for an L1 (measurement / report / triggering) event based on the best operating beam (e.g., the best beam direction associated with one SSB / CSI-RS / TRS of an LTM candidate) associated with one LTM candidate cell / current serving cell. In some implementations, the best beam may be based on the L1 (measurement) report (e.g., the largest L1-RSRP / RSRQ / RSSI / SINR value) associated with the candidate cell or the source cell.

[0129] In some implementations, the target CSI-RS configuration of LTM candidates may be configured via a current LTM-CSI-ResourceConfig IE in T 38.331 v18.2.0, as shown in Table 4 below.

[0130] In some implementations, the UE may derive the RS resource for a current beam of the serving cell (e.g., implicitly) based on the Quasi Co-Location (QCL) RS indicated by the TCI state (configuration). Therefore, for an activated TCI state of the serving cell, the UE may acquire the RS resource associated with the serving cell through an implicit approach. However, in some implementations, the serving RAN may also configure the RS resource configuration (e.g., CSI-RS / SSB / TRS) of the serving cell for the measurement / evaluation of a given L1 (measurement / report / triggering) events. In some implementations, the UE may also need to find the best beam of the serving cell for L1 (measurement / report / triggering) configurations based on the given TCI state configuration / RS resource configuration.

[0131] In some implementations, the L1 event associated with the current serving cell may be associated with (or limited by) a current operating beam. In some implementations, the L1 event associated with the current serving cell may be associated with the best beam observed by the UE (e.g., with a given period). In some implementations, the serving RAN may configure which beam (e.g., current beam / best beam) for the L1 event triggering / association (e.g., via an indication in the L1 event). In some implementations, both associations (e.g., associated with the current operating beam or associated with the best beam that the UE has measured / observed) may be supported by the UE / serving RAN. In some implementations, such a design may also be applicable to the LTM candidate cell and a neighbor cell.

[0132] In some implementations, the UE may derive the RS resource for one beam of the LTM candidate cell (e.g., implicitly) based on the QCL RS indicated by the TCI state (configuration) configured / activated by the serving RAN. Therefore, for an activated TCI state of the LTM candidate cell, the UE may acquire the RS resource associated with the serving cell through an implicit approach.

[0133] In some implementations, a specific L1 (measurement / report / triggering) event may be pre-configured with the RS (e.g., SSB / CSI-RS / TRS) configuration associated with a specific LTM candidate. In some implementations, several L1 events may share the same RS configuration.

[0134] Two-stages / Multi-stage activation

[0135] FIG. 3 is a diagram illustrating a signaling procedure of a two-stage activation of L1 event(s), according to an example implementation of the present disclosure.

[0136] Referring to FIG. 3, the serving RAN 32 may configure LTM configuration(s) 301 (e.g., an LTM-Config IE transmitted by the serving RAN via RRC signaling, as defined by 3GPP TS 38.331 v18.2.0) to the UE 31. The serving RAN 32 may configure or transmit an RRC signaling 302 (e.g., via the Reference configuration or via LTM candidate configurations) to the UE 31 to define or indicate a set of L1 (measurement / report / triggering) events (with or without threshold values) associated with one LTM candidate. The (DL) RRC signaling 303 may be defined as a 1ststage (L1 event) activation message 303. In some implementations, the 1ststage activation message 303 may include more than one LTM candidate and multiple sets of L1 (measurement / report / triggering) events. In some implementations, one set of L1 (measurement / report / triggering) events (with or without threshold values) may also be associated with multiple LTM candidates. The serving RAN 32 may then configure or transmit another downlink control signaling 305 (e.g., MAC CE / DCI) to activate one (or more than one) specific L1 (measurement / report / triggering) event (with or without thresholds) associated with one LTM candidate. The DL MAC CE / DCI signaling 305 may be defined as a 2ndstage (L1 event) activation message 305. The 2ndstage activation message 305 may not be the UE TA acquisition DCI or LTM CSC MAC CE, as described in conventional LTM operation.

[0137] In some implementations, the 2ndstage activation message 305 may further include an index value corresponding to the LTM candidate provided in the 1ststage activation message 303 if multiple LTM candidates are provided in the 1ststage activation message 303. Otherwise, the index value field may be absent.

[0138] In some implementations, the 2ndstage activation message 305 may further include an index value corresponding to at least one L1 (measurement / report / triggering) event in the set of L1 (measurement / report / triggering) events given in the 1ststage activation message 303. In some implementations, more than one index values may be provided to activate multiple L1 (measurement / report / triggering) events via the 2ndstage activation message 305.

[0139] In some implementations, the 2ndstage activation message 305 may further include thresholds value(s) of the L1 (measurement / report / triggering) event(s). In some implementations, the UE may apply the threshold values pre-configured by the serving RAN 32 (e.g., via reference configuration in LTM operation) if the threshold values of the L1 (measurement / report / triggering) events are absent in the 2ndstage activation message 305.

[0140] In some implementations, the 2ndstage activation message 305 may be implemented by one or more DCI / MAC CE.

[0141] In some implementations, the UE 31 may (start to / initiate) measure and evaluate the L1 (measurement / report / triggering) events after receiving the 2ndstage activation message 305. Then, the UE 31 may be enabled to trigger a (conditional) LTM Cell switch operation based on the L1 (measurement / report / triggering) events after receiving the 2ndstage activation message 305. Specifically, the UE 31 may determine (whether to) trigger the conditional LTM (SCS / operation) to which candidate cell based on the L1 events.

[0142] In some implementations, in a case that there is more than one LTM candidate for which the L1 (measurement / report / triggering) event is fulfilled, the UE 31 may decide the LTM candidate to perform LTM CSC based on UE implementation. In some implementations, the UE 31 may implement two or more actions (e.g., Action A / B / C / D / E) jointly or simultaneously in the time domain (e.g., based on UE implementations or based on RAN configuration).

[0143] In some implementations, the serving RAN 32 may pre-configure (e.g., via RRC signaling or the 1ststage activation message 303) the priority sequence of LTM candidates for the UE 31 to select LTM SCS operation(s) while there is more than one LTM candidate cell for which the L1(measurement / report / triggering) event is fulfilled. In some implementations, the UE 31 may implement LTM SCS operation based on the given priority sequence while there is more than one LTM candidate cell for which the L1(measurement / report / triggering) event is fulfilled or qualified. For example, the priority sequence for each LTM candidate cell may be included in the LTM candidate configuration for each LTM candidate cell in the RRC signaling (e.g., RRC reconfiguration message). Based on the given priority sequence, the UE 31 may only implement one LTM SCS operation, and the UE 31 may not initiate another one LTM SCS operation while a (conditional) LTM SCS operation is still ongoing.

[0144] In some implementations, the serving RAN 32 may also indicate or instruct the activated TCI state associated with at least one LTM candidate or one L1 (measurement / report / triggering) event in the 1ststage activation message 303 and / or the 2ndstage activation message 305. In addition, the UE 31 may evaluate the measurement / evaluation of one or more L1 events based on the activated TCI state (e.g., TCI state associated with serving cell and / or TCI state associated with LTM candidate).

[0145] In some implementations, the serving RAN 32 may also indicate or instruct the activated TCI state(s) associated with at least one LTM candidate or one L1 (measurement / report / triggering) event in the control signaling and / or the specific (e.g., LTM SCS command) MAC CE / DCI. In some implementations, the serving RAN 32 may configure the candidate TCI-state (e.g., by configuring the CandidateTCI-state IE and / or the CandidateTCI-UL-state IE) associated with a specific LTM candidate (cell) / L1 event.

[0146] In some implementations, the serving RAN 32 may configure the QCL-information (Quasi Co-Location) of an LTM candidate as the reference to a TCI state. In some implementations, the serving RAN 32 may transmit the TCIstateToaddModList IE (e.g., by referring to the dl-OrJointTCIStateToAddModList IE) to configure the TCI state list associated with the UE 31. Then, the serving RAN 32 may transmit the specific MAC CE / DCI to further activate the TCI state(s) associated with the target LTM candidate(s) / L1 event.

[0147] It should be noted that, other L1 / L3 event(s) (or combined L1 / L3 event) for other actions may also be applied to the mechanism described in FIG. 3.

[0148] L1 measurement result storage (MAC / RRC entity)

[0149] In some implementations, the UE may provide or store the L1 measurement results which are triggered by a given L1 (measurement / report / triggering) event in the VarMeasReportList IE.

[0150] In some implementations, the UE may provide or store L1 measurement results which are triggered by a given L1 (measurement / report / triggering) event in another VarMeasReportList-L1 IE, as shown in Table 5 below. In some implementations, the set of measId-L1 list may be configured or transmitted by the serving RAN to indicate one L1 measurement configuration (e.g., the measId-L1 may be associated with one L1 measurement object configuration and / or an L1 (measurement / report / triggering) event).

[0151] LTM serving cell switch execution (while the timer T311 is running, during an RRC re-establishment procedure)

[0152] In some implementations, the UE may not trigger any L1 measurement report to the serving RAN based on L1 (measurement / report / triggering) report configuration while the timer T311 is counting, even though the UE has been configured with any stored or configured L1 (measurement / report / triggering) event.

[0153] In some implementations, the UE may start T311 upon initiating an RRC connection re-establishment procedure. In some implementations, the UE may stop a running T311 timer upon selection of a suitable NR cell, or upon selection of a suitable L2 U2N Relay UE, or a cell using another RAT. In some implementations, the UE may move from RRC Connected state to RRC idle state while T311 expires.

[0154] Conditional LTM

[0155] (conditional early synchronization) Select the candidate beam / cell to trigger early synchronization

[0156] In some implementations, a UE may be configured or enabled (by the serving RAN) to select a candidate beam / cell to trigger early synchronization with one selected LTM candidate which fulfills at least one of the Layer-1 configured events.

[0157] (conditional LTM serving cell switch) Select the target beam / cell and trigger an LTM cell switch procedure

[0158] In some implementations, a UE may be configured or enabled (e.g., by the serving RAN) to select a candidate beam / cell to trigger conditional LTM serving cell switch operation while or upon at least one of the configured L1 events is fulfilled or triggered. In some implementations, the conditional LTM operation may include random access based conditional LTM operation and RACH-less conditional LTM operation.

[0159] In some implementations, a UE may be configured with one or more L1 events associated with RACH-based conditional LTM and RACH-less conditional LTM respectively from the serving RAN. Therefore, the UE may decide whether to initiate a random access procedure or not based on the type of conditional LTM associated with the triggering L1 event.

[0160] In some implementations, the UE may determine the type of LTM operation while more than one L1 event (and more than one conditional LTM SCS operation) is fulfilled at the UE side. In some implementations, the UE may prioritize one type of LTM SCS operation (e.g., RACH-less LTM operation is prioritized) based on the configuration from the serving RAN (e.g., the serving RAN may configure priority levels / sequences for RACH-less / RACH-based LTM SCS operation).

[0161] In some implementations, the UE may be configured with different priority values for different LTM candidates. The UE may decide the target LTM candidate of conditional LTM SCS operation while more than one L1 event (associated with more than one LTM candidate) is fulfilled. In other words, the UE may select an LTM candidate based on the given priority sequence for LTM SCS operation while more than one L1 event (associated with more than one LTM candidate) is fulfilled.

[0162] In some implementations, the UE may be configured or enabled to decide the target LTM candidate by itself while or upon multiple L1 triggering events (associated with more than one LTM candidate) are fulfilled.

[0163] Evaluation / Implementation entity (e.g., MAC entity / RRC entity)

[0164] In some implementations, the MAC entity of the UE may be configured by the RRC entity of the UE side with one or more L1 events associated with different actions (e.g., Action A / B / C / D / E).

[0165] In some implementations, each MAC entity (e.g., MAC entity associated with MCG / master node and / or MAC entity associated with SCG / secondary node) may be enabled or allowed to be independently configured with one or more L1 (measurement / report / triggering) events. In some implementations, only the MAC entity of MCG may be configured with L1 (measurement / report / triggering) events.

[0166] In some implementations, the L1 (measurement / report / triggering) events associated with MCG may be configured by the serving RAN via SRB1 / SRB3. The L1 (measurement / report / triggering) events associated with SCG may be configured by the serving RAN via SRB1 / SRB3.

[0167] In some implementations, the MAC entity associated with MCG / SCG may evaluate and trigger Action A / B / C independently (e.g., based on the TTT timer counting activity). Therefore, the Action A / B / C associated with MCG / SCG may be triggered or implemented jointly (with independent configurations) in the time domain.

[0168] In some implementations, the L1 (measurement / report / triggering) events may be allowed to be configured only with MCG / SCG.

[0169] In some implementations, only one cell group is capable of implementing Action A / B / C based on the given L1 (measurement / report / triggering) event in the time domain. Therefore, while one MAC entity (e.g., MAC entity associated with MCG or SCG) starts Action A / B / C based on an L1 (measurement / report / triggering) event, the UE may stop / suspend / release the evaluation / TTT timer counting activity of another MAC entity.

[0170] In some implementations, the MAC entities may report the L1 event (enter / leave) indication / L1 measurement result to the RRC entity.

[0171] TimeToTrigger (for Layer-3 beam / cell measurement) and TimeToTrigger-L1 Co-existence

[0172] In some implementations, the UE may be configured with a TimeToTrigger-L1 IE associated with one or more L1 (measurement / report / triggering) events. In addition, the UE may also be configured with a TimeToTrigger IE associated with one or more L3 cell / beam level-measurement reports. In such a case, the UE may be triggered to implement Action A / B / C while, upon, or after a running TimeToTrigger-L1 timer expires. In addition, the UE may stop a running TimeToTrigger timer of one or more or all L3 reporting procedures if there are any.

[0173] Joint triggering events for one LTM candidate

[0174] In some implementations, the serving RAN may configure different combinations of L1 (measurement / report / triggering) events towards a single LTM candidate. For example, the serving RAN may configure a set of L1 events {Event A2-b (1st L1 event), Event A4-b (2nd L1 event)}, where the 1st L1 event is associated with Action A (e.g., early synchronization procedure) and the 2nd L1 event is associated with Action C (e.g., LTM SCS operation).

[0175] In some implementations, the 1st L1 event or 2nd L1 event may be associated with multiple LTM candidates (or all of the configured LTM candidates). In some implementations, the 1st L1 event or 2nd L1 event may be associated with one given LTM candidate. In some implementations, the same L1 event may be associated with two or more different actions of one LTM candidate. In addition, in some implementations, the L1 event may be associated with the same threshold(s) / Time-To-Trigger configuration for the evaluation of different actions. In some implementations, different threshold(s) / Time-ToTrigger(s) of the same L1 event may be associated with different actions for the UE to evaluate whether to trigger the action (e.g., Action A / B / C / D / E) based on different values.

[0176] In some implementations, one LTM candidate may be limited to only one L1 event for one specific action. However, the L1 event may be associated with only one set of threshold / TTT or be associated with multiple threshold values / TTT(s) (so additional L1 control signaling may further indicate which threshold to apply for the L1 event evaluation).

[0177] In some implementations, an LTM candidate may be configured with a set of L1 events {Event A2-b (1st L1 event), Event A4-b (2nd L1 event)}. In some implementations, the UE may start to evaluate or implement the 2nd L1 event only upon the 1st L1 event being evaluated or triggered, or the action associated with the 1st L1 event being triggered or implemented successfully. In other words, the UE may not start to evaluate or implement the 2nd L1 event if the UE does not evaluate or implement the 1st L1 event yet, or the UE does not trigger or implement the action associated with the 1st L1 event successfully. In some implementations, the UE may measure / evaluate / implement the configured 1st L1 event and 2nd L1 event independently.

[0178] In some implementations, a specific action (e.g., either Action A / B / C / D / E) may be pre-configured to be associated with one or more LTM candidates. In addition, each LTM candidate may be further associated with one or more L1 events for the UE to trigger the given action.

[0179] In some implementations, an EarlySyncUp_conditional IE may be configured to the UE. The EarlySyncUp_conditional IE may include one or more LTM candidates (e.g., by giving the Physical Cell Identity of the LTM candidate) and one or more L1 events (e.g., by configuring the thresholds of trigger conditions and / or leave condition, TTT value) for the UE to initiate an early sync-up procedure during for LTM (SCS) preparation.

[0180] In some implementations, an LTM_CSC_Switch_Conditional IE may be configured to the UE. The LTM_CSC_Switch_Conditional IE may include one or more LTM candidates (e.g., by giving the Physical Cell Identity of the LTM candidate) and one or more L1 events (e.g., by configuring the thresholds of trigger conditions and / or leave condition, TTT value) for the UE to initiate an LTM SCS procedure.

[0181] In some implementations, while a UE starts or initiates an early synchronization procedure associated with one LTM candidate (e.g., LTM Candidate#1), the UE may stop the early synchronization evaluation procedure of other LTM candidates if there are any. Instead, the UE may only monitor or evaluate whether the conditional L1 events of LTM candidate#1 designed for LTM SCS operation (e.g., Action B) or other actions (e.g., Action C / D / E) are fulfilled or not. In some implementations, the UE may start to evaluate the L1 events of early synchronization (e.g., Action A) associated with other LTM candidates only upon or after the LTM SCS operation associated with the LTM candidate#1 is terminated successfully, the LTM SCS operation associated with the LTM candidate#1 is considered to fail, or the leave condition of the L1 event which the UE applied or used to trigger the early synchronization (e.g., Action A) with the LTM candidate#1 is fulfilled.

[0182] In some implementations, the serving RAN may configure an L1 (measurement / report / triggering) event but with different threshold values for different actions. In some implementations, the UE may be configured with an L1 Event A3-b and a set of thresholds {Threshold#1 (e.g., for Action A), Threshold#2 (e.g., for Action B)}. Therefore, the UE may evaluate the L1 event for Action A / B based on different threshold values. In this example, the value of Threshold#1 may be smaller than (or equivalent to) Threshold#2.

[0183] In some implementations, the serving RAN may configure one L1 (measurement / report / triggering) event with a single threshold. In such a case, the UE may implement Action A and Action B jointly towards one LTM candidate if the L1 event (associated with one LTM candidate) is fulfilled (and the TTT timer expires) by referring to the given threshold.

[0184] In some implementations, the serving RAN may configure one L1 (measurement / report / triggering) event with a single threshold and with different TTT values for different actions (e.g., TTT value T1 for Action A and TTT value T2 for Action B). In such a case, the UE may implement Action A when the L1 event is fulfilled for T1 and may implement Action B when the L1 event is fulfilled for T2.

[0185] In some implementations, for one LTM candidate, the serving RAN may only be able to configure one L1 event or a set of L1 events (e.g., {Event A2-b, Event A4-b}) to a single LTM candidate. In some implementations, one L1 event may be associated with one or multiple LTM candidates. For the serving RAN, one L1 event may be associated with a subset of (or all of the configured) LTM candidates (and so the association with one L1 (measurement / report / triggering) event ID and LTM candidate ID / index should be configured by the serving RAN).

[0186] Leave / cancel / Stop condition or L1 Leave / cancel / Stop event

[0187] In some implementations, a leave / cancel / stop condition may be configured with an L1 (measurement / report / triggering) event, which triggers the UE to stop an ongoing Action A / B / C after the ongoing action (A / B / C) is triggered or activated by the same L1 event.

[0188] In some implementations, an L1 leave / cancel / stop event may be configured to be associated with an L1 (measurement / report / triggering) event, which triggers the UE to stop an ongoing Action A / B / C after the ongoing action (A / B / C) is triggered or activated by the same L1 event.

[0189] The format / definition of an L1 (leave / cancel / stop) event may refer to an existing L1 (measurement / report / triggering) event. In some implementations, a specific L1 (measurement / report / triggering) event may be defined / configured as a leave / cancel / stop event while a specific action is triggered or implemented by the UE. While the leave / cancel / stop event is fulfilled, the UE may cancel / release / stop the ongoing action (and the LTM candidate may not be considered being selected).

[0190] In some implementations, a radio link failure event or a beam failure event associated with the LTM candidate may be defined as a leave / cancel / stop condition.

[0191] In some implementations, the leave / cancel / stop event may be an L3 cell-level / beam-level (report / triggering) event.

[0192] FIG. 4 is a diagram illustrating trigger and leave conditions, according to an example implementation of the present disclosure.

[0193] Referring to FIG. 4, in some implementations, an L1 (measurement / report / triggering) event (e.g., Event A4-b) may be configured with one threshold 401. The threshold 401 may be presented by DL-RSRP / DL-RSRQ / DL-SINR value. The UE may measure a DL-RSRP / DL-RSRQ / DL-SINR of one or more LTM candidates. Then, the UE may consider one Event A4-b is triggered / fulfilled upon or after the UE detects one (or more) LTM candidate(s) whose DL-RSRP / DL-RSRQ / DL-SINR values are larger than the threshold 401.

[0194] The UE may further decide a Trigger threshold 402 (e.g., by adding the threshold 401 with one additional hysteresis threshold 404) and / or a Leave threshold 403 (e.g., by decreasing the threshold 401 with one additional hysteresis value / threshold 404) if the hysteresis threshold 404 is configured to be associated with the L1 event (e.g., Event A4-b). In some implementations, the value of the hysteresis value 404 may be zero, and this means the value of the trigger threshold 402 / leave threshold 403 is the same as the threshold 401.

[0195] The UE may trigger a TTT timer upon or after the DL-RSRP / DL-RSRQ / DL-SINR values of the same LTM candidate (e.g., the LTM candidate which fulfills the threshold requirement) is higher than the Trigger threshold 402 (e.g., at time point 41). The UE may keep counting the TTT timer to zero (e.g., at time point 42) if the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate are still higher than the Trigger threshold 402. Otherwise, the UE may stop the TTT timer once the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate become lower than the Trigger threshold 402. In some implementations, the UE may re-start the TTT timer upon or after the UE finds out the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate become higher than the Trigger threshold 402 again. The UE may repeat the TTT timer stop / reset implementations before the TTT timer is counted to zero successfully or upon the leave condition (of the same LTM candidate / L1 event) is fulfilled (e.g., the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate become lower than the leave threshold 403).

[0196] In some implementations, the initial value of the TTT timer / L1 event threshold 401 / hysteresis value 404 / trigger threshold 402 / leave threshold 403 may be pre-configured to the UE (with associated L1 event / LTM candidate) as part of LTM configuration / reference configuration.

[0197] In some implementations, different initial values of the TTT timer / L1 event threshold 401 / hysteresis value 404 / trigger threshold 402 / leave threshold 403 may be associated with different LTM candidates. In some implementations, different initial values of TTT timer / L1 event threshold 401 / hysteresis value 404 / trigger threshold 402 / leave threshold 403 may be associated with different actions (e.g., Action A / B / C / D / E). In some implementations, different initial values of TTT timer / L1 event threshold 401 / hysteresis value 404 / trigger threshold 402 / leave threshold 403 may be associated with different L1 events.

[0198] In some implementations, the UE may start / initiate Action A / B / C or the additional Action D / E upon or after the TTT timer is counted to zero (e.g., at time point 42).

[0199] In some implementations, a leave condition 403 may also be defined for the L1 event (and the LTM candidate which triggers the L1 event). As shown in FIG. 4, the leave threshold 403 may be decided based on the L1 event threshold 401 with a hysteresis value 404. Then, in the L1 Event (e.g., Event A4-b), the UE may stop the triggered action (e.g., Action A / B / C) upon or after the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate become lower than the leave threshold 403.

[0200] FIG. 5 is a diagram illustrating a signaling procedure of an LTM SCS operation, according to an example implementation of the present disclosure.

[0201] Referring to FIG. 5, in action 501, the UE 51 may send a MeasurementReport message to the serving RAN 52 (e.g., to the serving / source gNB / BS which configures one or more serving cells to the UE). In action 502, the RAN 52 (e.g., serving / source gNB / BS of the UE) may decide to configure LTM and initiates LTM preparation. In action 503, the RAN 52 (e.g., serving gNB / BS of the UE) may transmit an RRCReconfiguration message to the UE 51 including the LTM candidate configurations (e.g., via the serving / source cells configured by the serving / source gNB / BS). In action 504, the UE 51 may store the LTM candidate configurations and transmit an RRCReconfigurationComplete message to the RAN 52 (e.g., to the serving / source gNB / BS). The LTM preparation may be completed by action 504.

[0202] In action 505, the UE 51 may perform DL synchronization with the LTM candidate cell(s) before receiving the cell switch command. The UE 51 may activate and deactivate TCI states of LTM candidate cell(s), which are configured by one or more gNBs / BSs of the serving RAN 52, as triggered by the gNB. In action 506, the UE 51 may perform UL synchronization with LTM candidate cell(s) (configured by the one or more gNBs / BSs of the serving RAN 52) 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 RAN 52. When UE-based TA measurement is configured, the UE 51 may acquire the TA value(s) of the candidate cell(s) by measurement. The UE 51 may perform early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command (e.g., as specified in clause 9.2.6 of 3GPP TS 38.300). This may be done via CFRA triggered by a PDCCH order from the source cell, following which the UE 51 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 51 may not receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE 51 may not maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity.

[0203] In action 507, the UE 51 may perform L1 measurements on the configured LTM candidate cell(s) and transmit L1 measurement reports to the RAN 52. The L1 measurement(s) may be performed as long as RRC reconfiguration (e.g., action 503) is applicable. 　　　　In action 508, the RAN 52 may decide to execute cell switch to a target cell (e.g., triggered by the source / serving gNB / BS which serves the UE), and in action 509, the RAN 52 (e.g., the source / serving gNB / BS and so the source / serving cell) may transmit an LTM cell switch command MAC CE triggering cell switch by including a target configuration ID which 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 action 510, the UE 51 may switch to the target cell and apply the candidate configuration indicated by the target configuration ID.

[0204] In action 511, the UE 51 may perform the random access procedure towards the target cell (e.g., target cell configured by a target gNB / BS, which is also part of the RAN 52), if UE 51 does not have valid TA of the target cell as specified in clause 5.18.35 of 3GPP TS 38.321. In action 512, the UE 51 may complete the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell (e.g., and so to the target gNB / BS). If the UE 51 has performed a RA procedure in action 511 the UE 51 may consider that LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE 51 may consider that LTM cell switch execution is successfully completed when the UE 51 determines that the network has successfully received its first UL data.

[0205] The actions 505 to 512 may be performed multiple times for subsequent LTM cell switch executions using the LTM candidate configuration(s) provided in action 503. The procedure over the air interface described in FIG. 5 may be applicable to both intra-gNB-DU LTM and inter-gNB-DU LTM. The overall LTM procedures over F1-C interface may be captured in 3GPP TS 38.401 v18.2.0.

[0206] FIG. 6 is a flowchart illustrating a method / process 600 performed by a UE for utilizing L1 triggering events, according to an example implementation of the present disclosure.

[0207] In the action 602, the process 600 may start by receive, from a BS, an RRC configuration of one or more L1 triggering events associated with one or more candidate cells. Each of the one or more L1 triggering events configured with a reference signal type, a reference signal quality and a TTT value (e.g., of a TTT timer) and associated with one of the one or more candidate cells. The RRC configuration may further configure multiple actions which are associated with the one or more L1 triggering events.

[0208] In some implementations, the one or more L1 triggering events may include one or more of the following: 　　　　- a first signal quality of a beam associated with a serving cell becoming better than a first absolute threshold, 　　　　- the first signal quality of the beam associated with the serving cell becoming worse than a second absolute threshold, 　　　　- a second signal quality of a beam associated with a candidate cell becoming better than a third signal quality of a beam associated with a primary cell (PCell), a primary secondary cell (PSCell), or the serving cell by a first offset, 　　　　- the second signal quality of the beam associated with the candidate cell becoming better than a third absolute threshold, 　　　　- the first signal quality of the beam associated with the serving cell becoming worse than a fourth absolute threshold and the second signal quality of the beam associated with the candidate cell becoming better than a fifth absolute threshold, and 　　　　- a fourth signal quality of a beam associated with a neighboring cell becoming better than a fifth signal quality of a beam associated with a secondary cell (SCell).

[0209] In some implementations, the multiple actions may include: 　　　　- performing an early synchronization with a target candidate cell, 　　　　- performing an LTM cell switch procedure with the target candidate cell, and 　　　　- transmitting the L1 measurement result to a serving RAN.

[0210] In some implementations, the multiple actions may include one or more of the following: 　　　　- performing or halting an L3 measurement, 　　　　- performing or halting an L3 measurement reporting, and 　　　　- performing a conditional mobility operation, which may include at least one of a conditional handover, a conditional PSCell addition, and a conditional PSCell change.

[0211] In some implementations, the UE may further receive, from the BS, DCI / MAC CE that includes an indication to activate at least one of the one or more L1 triggering events.

[0212] In some implementations, the UE may further receive, from the BS, a reference configuration and a delta configuration. The reference configuration may include a default configuration (e.g., a default setting of the rsType and / or rsQuantity) for the one or more L1 triggering event and the associated one or more candidate cells. The delta configuration (e.g., a delta setting of the rsType and / or rsQuantity for adjusting or overriding the default setting) may be associated with one of the one or more L1 triggering event or with one of the one or more candidate cells.

[0213] Referring to FIG. 6, in action 604, the process 600 may obtain an L1 measurement result by performing a physical layer measurement on the one or more candidate cells.

[0214] In some implementations, the UE may determine a beam for performing the physical layer measurement. The beam may include one of the following: 　　　　- a current TCI beam associated with a serving cell; 　　　　- a best beam determined based on a DL-RSRP; 　　　　- a best beam, among one or more activated TCI-state beams, determined based on the DL-RSRP; and 　　　　- a beam configured by a (e.g., serving) RAN.

[0215] Referring to FIG. 6, in action 606, the process 600 may determine, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied. In response to determining that the at least one of the one or more L1 triggering events is satisfied, in action 608, the process 600 may initiate one or more of the actions, configured in the RRC configuration (received in action 602), with a target candidate cell among the one or more candidate cells. The process 600 may then end. Specifically, the target candidate cell may be determined when the L1 triggering event(s) associated with the target candidate cell are satisfied.

[0216] In some implementations, when the reference configuration and the delta configuration are received by the UE, the initiation of the one or more actions may be determined by combining the reference configuration and the delta configuration.

[0217] In some implementations, the UE may determine, based on the L1 measurement result, whether an entering condition or a leaving condition is satisfied. For example, the entering condition may be the triggering condition (e.g., the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate become higher than the trigger threshold 402) and the leave condition (e.g., the DL-RSRP / DL-RSRQ / DL-SINR measurement results of the same LTM candidate become lower than the leave threshold 403) as illustrated in FIG. 4. In response to determining the entering condition has been continuously satisfied for a first duration indicated by a first TTT value (e.g., configured in the RRC configuration received in action 602) associated with the entering condition satisfied, the UE may determine to initiate the one or more of the multiple actions. In response to determining that the leaving condition has been continuously satisfied for a second duration indicated by a second TTT value (e.g., configured in the RRC configuration received in action 602) associated with the leaving condition, the UE may determine to halt the one or more of the multiple actions.

[0218] Based on the above, implementations of the present disclosure may leverage L1 (e.g., physical layer) measurements and trigger events for mobility management in wireless systems, enabling faster and more granular decisions compared to the L3 approaches. By configuring L1 events with reference signal types (e.g., SSB or CSI-RS), signal qualities (e.g., beam-specific RSRP / SINR rather than L3’s averaged cell quality), and TTT values via RRC, the UE may perform physical layer measurements on candidate cells, evaluates event satisfaction, and initiates actions like early synchronization, or LTM cell switching, etc. Such a design may reduce handover latency to near-zero in L1 / L2, enhance beam-level precision in high-frequency scenarios, reduce signaling overhead, and improve power efficiency for dynamic environments.

[0219] FIG. 7 is a block diagram illustrating a node 700 for wireless communication in accordance with various aspects of the present disclosure. As illustrated in FIG. 7, a node 700 may include a transceiver 720, a processor 728, a memory 734, one or more presentation components 738, and at least one antenna 736. The node 700 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. 7).

[0220] Each of the components may directly or indirectly communicate with each other over one or more buses 740. The node 700 may be a UE or a BS that performs various functions disclosed with reference to FIGS. 1 to 6.

[0221] The transceiver 720 has a transmitter 722 (e.g., transmitting / transmission circuitry) and a receiver 724 (e.g., receiving / reception circuitry) and may be configured to transmit and / or receive time and / or frequency resource partitioning information. The transceiver 720 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 720 may be configured to receive data and control channels.

[0222] The node 700 may include a variety of computer-readable media. Computer-readable media may be any available media that may be accessed by the node 700 and include volatile (and / or non-volatile) media and removable (and / or non-removable) media.

[0223] 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, or data.

[0224] 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, 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.

[0225] 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.

[0226] The memory 734 may include computer-storage media in the form of volatile and / or non-volatile memory. The memory 734 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. 7, the memory 734 may store a computer-readable and / or computer-executable instructions 732 (e.g., software codes) that are configured to, when executed, cause the processor 728 to perform various functions disclosed herein, for example, with reference to FIGS. 1 to 6. Alternatively, the instructions 732 may not be directly executable by the processor 728 but may be configured to cause the node 700 (e.g., when compiled and executed) to perform various functions disclosed herein.

[0227] The processor 728 (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 728 may include memory. The processor 728 may process the data 730 and the instructions 732 received from the memory 734, and information transmitted and received via the transceiver 720, the baseband communications module, and / or the network communications module. The processor 728 may also process information to send to the transceiver 720 for transmission via the antenna 736 to the network communications module for transmission to a CN.

[0228] One or more presentation components 738 may present data indications to a person or another device. Examples of presentation components 738 may include a display device, a speaker, a printing component, a vibrating component, etc.

[0229] 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 utilizing Layer-1 (L1) triggering events in a wireless communication system, 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 Base Station (BS), a radio resource control (RRC) configuration of one or more L1 triggering events associated with one or more candidate cells, each of the one or more L1 triggering events configured with a reference signal type, a reference signal quality and a time-to-trigger (TTT) value and associated with one of the one or more candidate cells; 　　　　　　　　obtain an L1 measurement result by performing a physical layer measurement on the one or more candidate cells; 　　　　　　　　determine, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied; and 　　　　　　　　in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiate one or more of a plurality of actions with a target candidate cell among the one or more candidate cells, the plurality of actions configured in the RRC configuration to be associated with the one or more L1 triggering events, 　　　　　　　　wherein the plurality of actions comprises: 　　　　　　　　　　　　performing an early synchronization with the target candidate cell, 　　　　　　　　　　　　performing a Layer-1 / Layer-2 triggered mobility (LTM) cell switch procedure with the target candidate cell, and 　　　　　　　　　　　　transmitting the L1 measurement result to a serving random access network (RAN).

2. The UE of claim 1, wherein obtaining the L1 measurement result by performing the physical layer measurement comprises: 　　　　determining a beam for performing the physical layer measurement, wherein the beam comprises one of: 　　　　a current transmission configuration indicator (TCI) beam associated with a serving cell; 　　　　a best beam determined based on a downlink reference signal received power (DL-RSRP) 　　　　a best beam, among one or more activated TCI-state beams, determined based on the DL-RSRP; and 　　　　a beam configured by a radio access network (RAN).

3. The UE of claim 1, wherein the plurality of actions further comprises: 　　　　performing or halting an L3 measurement, 　　　　performing or halting an L3 measurement reporting, and 　　　　performing a conditional mobility operation, the conditional mobility operation comprising at least one of a conditional handover, a conditional Primary Secondary Cell (PSCell) addition, and a conditional PSCell change.

4. The UE of claim 1, wherein in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiating the one or more of the plurality of actions with the target candidate cell among the one or more candidate cells comprises: 　　　　determining, based on the L1 measurement result, whether an entering condition or a leaving condition is satisfied; 　　　　in response to determining that the entering condition has been continuously satisfied for a first duration indicated by a first TTT value associated with the entering condition satisfied, determining to initiate the one or more of the plurality of actions; 　　　　in response to determining that the leaving condition has been continuously satisfied for a second duration indicated by a second TTT value associated with the leaving condition satisfied, determining to halt the one or more of the plurality of actions, 　　　　wherein the first TTT and the second TTT are configured in the RRC configuration.

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 BS, a reference configuration comprising a default configuration for the one or more L1 triggering event and the associated one or more candidate cells; 　　　　receive, from the BS, a delta configuration associated with one of the one or more L1 triggering event or with one of the one or more candidate cells; and 　　　　initiate the one or more of the plurality of actions associated with the at least one of the one or more L1 triggering events satisfied on the target candidate cell by combining the reference configuration and the delta configuration.

6. The UE of claim 1, wherein the one or more L1 triggering events comprises one or more of the following: 　　　　a first signal quality of a beam associated with a serving cell becoming better than a first absolute threshold, 　　　　the first signal quality of the beam associated with the serving cell becoming worse than a second absolute threshold, 　　　　a second signal quality of a beam associated with a candidate cell becoming better than a third signal quality of a beam associated with a primary cell (PCell), a primary secondary cell (PSCell), or the serving cell by a first offset, 　　　　the second signal quality of the beam associated with the candidate cell becoming better than a third absolute threshold, 　　　　the first signal quality of the beam associated with the serving cell becoming worse than a fourth absolute threshold and the second signal quality of the beam associated with the candidate cell becoming better than a fifth absolute threshold, and 　　　　a fourth signal quality of a beam associated with a neighboring cell becoming better than a fifth signal quality of a beam associated with a secondary cell (SCell).

7. 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 BS, a medium access control control element (MAC CE) or downlink control information (DCI) comprising an indication to activate at least one of the one or more L1 triggering events.

8. A Base Station (BS) for utilizing Layer-1 (L1) triggering events in a wireless communication system, 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), a radio resource control (RRC) configuration of one or more L1 triggering events associated with one or more candidate cells, each of the one or more L1 triggering events configured with a reference signal type, a reference signal quality and a time-to-trigger (TTT) value and associated with one of the one or more candidate cells, 　　　　wherein: 　　　　　　　　the RRC configuration causes the UE to: 　　　　　　　　　　　　obtain an L1 measurement result by performing a physical layer measurement on the one or more candidate cells; 　　　　　　　　　　　　determine, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied; and 　　　　　　　　　　　　in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiate one or more of the plurality of actions with a target candidate cell among the one or more candidate cells, the plurality of actions configured in the RRC configuration to be associated with the one or more L1 triggering events, and 　　　　　　　　the plurality of actions comprises: 　　　　　　　　　　　　performing an early synchronization with the target candidate cell, 　　　　　　　　　　　　performing a Layer-1 / Layer-2 triggered mobility (LTM) cell switch procedure with the target candidate cell, and 　　　　　　　　　　　　transmitting the L1 measurement result to a serving random access network (RAN).

9. The BS of claim 8, wherein the RRC configuration further causes the UE to: 　　　　determine a beam for performing the physical layer measurement, wherein the beam comprises one of: 　　　　a current transmission configuration indicator (TCI) beam associated with a serving cell; 　　　　a best beam determined based on a downlink reference signal received power (DL-RSRP) 　　　　a best beam, among one or more activated TCI-state beams, determined based on the DL-RSRP; and 　　　　a beam configured by a radio access network (RAN).

10. The BS of claim 8, wherein the plurality of actions further comprises: 　　　　performing or halting an L3 measurement, 　　　　performing or halting an L3 measurement reporting, and 　　　　performing a conditional mobility operation, the conditional mobility operation comprising at least one of a conditional handover, a conditional Primary Secondary Cell (PSCell) addition, and a conditional PSCell change.

11. The BS of claim 8, wherein the RRC configuration comprises a first TTT value and a second TTT value, and further causes the UE to: 　　　　determine, based on the L1 measurement result, whether an entering condition or a leaving condition is satisfied; 　　　　in response to determining that the entering condition has been continuously satisfied for a first duration indicated by the first TTT value associated with the entering condition satisfied, determine to initiate the one or more of the plurality of actions; and 　　　　in response to determining that the leaving condition has been continuously satisfied for a second duration indicated by the second TTT value associated with the leaving condition satisfied, determine to halt the one or more of the plurality of actions.

12. The BS of claim 8, 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, a reference configuration comprising a default configuration for the one or more L1 triggering event and the associated one or more candidate cells; and 　　　　transmit, to the UE, a delta configuration associated with one of the one or more L1 triggering event or with one of the one or more candidate cells, 　　　　wherein the RRC configuration, the reference configuration, and the delta configuration cause the UE to: 　　　　　　　　initiate the one or more of the plurality of actions associated with the at least one of the one or more L1 triggering events satisfied on the target candidate cell by combining the reference configuration and the delta configuration.

13. The BS of claim 8, wherein the one or more L1 triggering events comprises one or more of the following: 　　　　a first signal quality of a beam associated with a serving cell becoming better than a first absolute threshold, 　　　　the first signal quality of the beam associated with the serving cell becoming worse than a second absolute threshold, 　　　　a second signal quality of a beam associated with a candidate cell becoming better than a third signal quality of a beam associated with a primary cell (PCell), a primary secondary cell (PSCell), or the serving cell by a first offset, 　　　　the second signal quality of the beam associated with the candidate cell becoming better than a third absolute threshold, 　　　　the first signal quality of the beam associated with the serving cell becoming worse than a fourth absolute threshold and the second signal quality of the beam associated with the candidate cell becoming better than a fifth absolute threshold, and 　　　　a fourth signal quality of a beam associated with a neighboring cell becoming better than a fifth signal quality of a beam associated with a secondary cell (SCell).

14. The BS of claim 8, 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, a medium access control control element (MAC CE) or downlink control information (DCI) comprising an indication to activate at least one of the one or more L1 triggering events.

15. A method performed by a User Equipment (UE) for utilizing Layer-1 (L1) triggering events in a wireless communication system, the method comprising: 　　　　receiving, from a Base Station (BS), a radio resource control (RRC) configuration of one or more L1 triggering events associated with one or more candidate cells, each of the one or more L1 triggering events configured with a reference signal type, a reference signal quality and a time-to-trigger (TTT) value and associated with one of the one or more candidate cells; 　　　　obtaining an L1 measurement result by performing a physical layer measurement on the one or more candidate cells; 　　　　determining, based on the L1 measurement result, whether at least one of the one or more L1 triggering events is satisfied; and 　　　　in response to determining that the at least one of the one or more L1 triggering events is satisfied, initiating one or more of a plurality of actions with a target candidate cell among the one or more candidate cells, the plurality of actions configured in the RRC configuration to be associated with the one or more L1 triggering events, 　　　　wherein the plurality of actions comprises: 　　　　　　　　performing an early synchronization with the target candidate cell, 　　　　　　　　performing a Layer-1 / Layer-2 triggered mobility (LTM) cell switch procedure with the target candidate cell, and 　　　　　　　　transmitting the L1 measurement result to a serving random access network (RAN).

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