WO2025036301A1

WO2025036301A1 - Method and device for l1/l2 triggered mobility

Info

Publication number: WO2025036301A1
Application number: PCT/CN2024/111131
Authority: WO
Inventors: Wanchen LIN; Meiju SHIH; Chiahung Lin
Original assignee: FG Innovation Co Ltd
Current assignee: FG Innovation Co Ltd
Priority date: 2023-08-11
Filing date: 2024-08-09
Publication date: 2025-02-20
Anticipated expiration: 2026-02-11

Abstract

A method for layer 1/layer 2 (L1/L2) triggered mobility (LTM) performed by a user equipment (UE) is provided. The method receives a radio resource control (RRC) reconfiguration message. The RRC reconfiguration message includes one or more measurement gap configurations and an index for each of the one or more measurement gap configurations. The method further receives a medium access control (MAC) control element (CE) which includes a first field indicating one of the one or more measurement gap configurations using the index, and performs an inter-frequency-based measurement based on the one of the one or more measurement gap configurations. Each of the one or more measurement gap configurations is associated with a Synchronization Signal Block (SSB) resource or a Channel State Information-Reference Signal (CSI-RS) resource.

Description

METHOD AND DEVICE FOR L1/L2 TRIGGERED MOBILITY

CROSS-REFERENCE TO RELATED APPLICATION (S)

The present disclosure claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 63/532,216, filed on August 11, 2023, entitled “METHOD AND APPARATUS FOR HANDLING MEASUREMENT GAP FOR LTM, ” the content of which is hereby incorporated herein fully by reference into the present disclosure for all purposes.

FIELD

The present disclosure generally relates to wireless communications and, more particularly, to methods and devices for Layer 1/Layer 2 (L1/L2) triggered mobility.

BACKGROUND

Various efforts have been made to improve different aspects of wireless communication for cellular wireless communication systems, such as the 5^th Generation (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 is a need for further improvements in wireless communication in the next-generation wireless communication systems.

SUMMARY

The present disclosure is directed to methods and devices for Layer 1/Layer 2 (L1/L2) triggered mobility (LTM) .

According to a first aspect of the present disclosure, a method for LTM performed by a user equipment (UE) is provided. The method includes receiving a radio resource control (RRC) reconfiguration message, the RRC reconfiguration message including one or more measurement gap configurations and an index for each of the one or more measurement gap configurations; receiving a medium access control (MAC) control element (CE) , the MAC CE including a first field indicating one of the one or more measurement gap configurations using the index; and performing an inter-frequency-based measurement based on the one of the one or more measurement gap configurations. Each of the one or more measurement gap configurations is associated with a synchronization signal block (SSB) resource or a channel state information-reference signal (CSI-RS) resource.

In some implementations of the first aspect of the present disclosure, the method further includes: switching to a target cell based on a measurement result of the inter-frequency-based measurement.

In some implementations of the first aspect of the present disclosure, the RRC reconfiguration message further includes a measurement gap length, a measurement gap offset, measurement repetition information, a reference cell, reference SSB information, and reference CSI-RS information, for each of the one or more measurement gap configurations.

In some implementations of the first aspect of the present disclosure, the measurement gap length is in units of symbols.

In some implementations of the first aspect of the present disclosure, each of the one or more measurement gap configurations is configured to be applied to a frequency band.

In some implementations of the first aspect of the present disclosure, the MAC CE further includes a cell switch command.

In some implementations of the first aspect of the present disclosure, the MAC CE further includes a second field indicating an SSB index or a CSI-RS index, and the SSB index or the CSI-RS index indicated by the second field is associated with the one of the one or more measurement gap configurations indicated by the first field.

According to a second aspect of the present disclosure, a user equipment (UE) is provided. The UE includes one or more processors 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 of the one or more processors, cause the UE to: receive a radio resource control (RRC) reconfiguration message, the RRC reconfiguration message including one or more measurement gap configurations and an index for each of the one or more measurement gap configurations; receive a medium access control (MAC) control element (CE) , the MAC CE including a first field indicating one of the one or more measurement gap configurations using the index; and perform an inter-frequency-based measurement based on the one of the one or more measurement gap configurations. Each of the one or more measurement gap configurations is associated with a synchronization signal block (SSB) resource or a channel state information-reference signal (CSI-RS) resource.

In some implementations of the second aspect of the present disclosure, the one or more computer-executable instructions, when executed by the at least one of the one or more processors, further cause the UE to: switch to a target cell based on a measurement result of the inter-frequency-based measurement.

In some implementations of the second aspect of the present disclosure, the RRC reconfiguration message further includes a measurement gap length, a measurement gap offset, measurement repetition information, a reference cell, reference SSB information, and reference CSI-RS information, for each of the one or more measurement gap configurations.

In some implementations of the second aspect of the present disclosure, the measurement gap length is in units of symbols.

In some implementations of the second aspect of the present disclosure, each of the one or more measurement gap configurations is configured to be applied to a frequency band.

In some implementations of the second aspect of the present disclosure, the MAC CE further includes a cell switch command.

In some implementations of the second aspect of the present disclosure, the MAC CE further includes a second field indicating an SSB index or a CSI-RS index, and the SSB index or the CSI-RS index indicated by the second field is associated with the one of the one or more measurement gap configurations indicated by the first field.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 is a flowchart for a method/process for Layer 1/Layer 2 Triggered Mobility, according to an example implementation of the present disclosure.

FIG. 2 is a block diagram illustrating a node for wireless communication, according to an example implementation of the present disclosure.

DETAILED DESCRIPTION

The terms mentioned in the present disclosure are defined as follows. Unless otherwise specified, the terms in the present disclosure have the following meanings.
Abbreviation          Full name
3GPP                 3rd Generation Partnership Project
5G                   5th generation
ACK                 Acknowledgment
AL                   Aggregation level
ARFCN               Absolute Radio Frequency Channel Number
BFD                  Beam Failure Detection
BWP                 Band Width Part
CA                   Carrier Aggregation
CORESET             Control resource set
CC                   Component Carrier
CCE                  Control Chanel Element
CRC                  Cyclic Redundancy Check
C-RNTI               Cell Radio Network Temporary Identifier
CS-RNTI              Configured Scheduling Radio Network Temporary Identifier
CSS                  Common Search Space
CSI                  Channel State Information
DC                   Dual Connectivity
DCI                  Downlink Control Information
DL                   Downlink
GC-PDCCH           Group Common Physical Downlink Control Channel
HARQ                Hybrid Automatic Repeat Request
IE                    Information Element
IIoT                  Industrial Internet of Things
LSB                  Least Significant Bit
LTE                  Long Term Evolution
L1                    Layer 1
L2                   Layer 2
LTM                 L1/L2 Triggered Mobility
MAC                Medium Access Control
MCG                Master Cell Group
MCS-C-RNTI         Modulation Coding Scheme Cell Radio Network Temporary Identifier
mTRP               Multiple Transmission Reception Point
MIMO               Multiple-input Multiple-output
MSB                Most Significant Bit
NACK               Negative Acknowledgment
NDI                 New Data Indicator
NR                  New RAT/Radio
NW                 Network
NUL                 Normal UL
PCI                  Physical Cell ID
PCell                Primary Cell
PSCell               Primary Secondary Cell
PBCH               Physical Broadcast Channel
PDCCH              Physical Downlink Control Channel
PDSCH              Physical Downlink Shared Channel
PDU                 Protocol Data Unit
PHY                 Physical
PRACH              Physical Random Access Channel
PTAG               Primary Timing Advance Group
PUCCH              Physical Uplink Control Channel
PUSCH              Physical Uplink Shared Channel
RA                  Random Access
RAN                Radio Access Network
RAR                Random Access Response
Rel                  Release
RMSI                Remaining Minimum System Information
RNTI                Radio Network Temporary Identifier
RRC                 Radio Resource Control
RRM                Radio Resource Measurement
RS                   Reference Signal
RSRP                Reference Signal Received Power
RV                   Redundancy Version
SCell                 Secondary Cell
SCG                  Secondary Cell Group
SCS                  Subcarrier Spacing
SDM                 Spatial Division Multiplexing
SINR                 Signal to Interference plus Noise Ratio
SpCell                Special Cell
SR                   Scheduling Request
SRS                  Sounding Reference Signal
SRI                  SRS Resource Indicator
SSB                  Synchronization Signal Block
STAG                Secondary Timing Advance Group
STxMP               Simultaneous Transmission on Multiple Panels
SUL                  Supplementary UL
TA                   Timing Advance
TAG                 Timing Advance Group
TB                   Transport Block
TBS                  Transport Block Size
TCI                  Transmission Configuration Indication
TPMI                 Transmission Precoding Matrix Indicator
TR                   Technical Report
TRP                  Transmission Reception Point
TS                   Technical Specification
QCL                 Quasi-CoLocation
UE                   User Equipment
UL                   Uplink
URLLC               Ultra Reliable Low Latency Communication
USS                  UE-Specific Search Space
WG                  Working Group
WI              Working Item

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.

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.

For 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 shall not be narrowly included to what is illustrated in the drawings.

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 one implementation, ” 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.

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.

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.

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.

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) .

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.

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.

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.

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.

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.

The BS is operable to provide radio coverage to a specific geographical area using multiple cells forming the RAN. The BS supports the operations of the cells. Each cell is operable to provide services to at least one UE within its radio coverage.

Each cell (often referred to as a serving cell) provides services to serve one or more UEs within its 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. The BS may communicate with one or more UEs in the radio communication system via multiple cells.

A cell may allocate sidelink (SL) resources for supporting Proximity Service (ProSe) or Vehicle to Everything (V2X) service. Each cell may have overlapped coverage areas with other cells.

In Multi-RAT Dual Connectivity (MR-DC) scenario, the primary cell of a Master Cell Group (MCG) or a Secondary Cell Group (SCG) may be called 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.

As described above, the frame structure for NR supports 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.

Two coding schemes are 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.

At least 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.

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.

Any sentence, paragraph, (sub) -bullet, point, action, behavior, term, or claim described in the present disclosure may be implemented independently and separately to form a specific method.

Dependency (e.g., “based on” , “more specifically” , “preferably” , “in one embodiment” , “in some implementations” , etc. ) in the present disclosure may be only one possible example and shall not restrict the specific method.

“A and/or B, ” in the present disclosure, may include either A or B, both A and B, or at least one of A and B.

Examples of some selected terms are provided as follows.

Cell: A radio network object that may be uniquely identified by a User Equipment from a (cell) identification that is broadcast over a geographical area from, for example, a UTRAN Access Point. A Cell is either in an FDD mode or a TDD mode.

Serving Cell: For a UE in the RRC_CONNECTED state, that is not configured with CA/DC, there is only one serving cell including a primary cell. For a UE in the RRC_CONNECTED state, that is configured with CA/DC, the term ‘serving cells’ is used to denote a set of cells including the Special Cell (s) and all secondary cells.

CA: In Carrier Aggregation (CA) scenario, two or more Component Carriers (CCs) are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is deployed, the frame timing and SFN may be aligned across cells that are capable of aggregation. The maximum number of configured CCs for a UE is 16 for DL and 16 for UL. When CA is configured, the UE may only have one RRC connection with the network. At the RRC connection establishment/re-establishment/handover, a serving cell may provide the NAS mobility information, and at the RRC connection re-establishment/handover, a serving cell may provide the security input. Such a cell may be referred to as the Primary Cell (PCell) . Depending on the UE capabilities, Secondary Cells (SCells) may be configured to form, together with the PCell, a set of serving cells. Therefore, the configured set of serving cells for a UE may always include one PCell and one or more SCells.

BWP: A subset of the total cell bandwidth of a cell is referred to as a Bandwidth Part (BWP) and a Bandwidth Adaptation (BA) may be achieved by configuring the UE with BWP (s) and instructing the UE which of the configured BWPs is currently the active one. To enable a BA on the PCell, the gNB configures the UE with UL and DL BWP (s) . To enable the BA on SCells, in case of CA, the gNB configures the UE with at least one or more DL BWPs (e.g., there may be no BWP in the UL) . For the PCell, the initial BWP is the BWP used for an initial access. For the SCell (s) , the initial BWP is the BWP configured for the UE to operate after an SCell activation. The UE may be configured with a first active uplink BWP by a firstActiveUplinkBWP IE. If the first active uplink BWP is configured for an SpCell, the firstActiveUplinkBWP IE field may contain the ID of the UL BWP to be activated upon performing the RRC (re-) configuration. If the field is absent, the RRC (re-) configuration does not impose a BWP switching. If the first active uplink BWP is configured for an SCell, the firstActiveUplinkBWP IE field contains the ID of the uplink bandwidth part to be used upon the MAC-activation of an SCell.

Timer: A MAC entity may set up one or more timers for different purposes, for example, triggering one or more uplink signaling retransmissions or limiting one or more uplink signaling retransmission periods. A timer is running once it is started, until it is stopped, or until it expires; otherwise, it is not running. A timer may be started if it is not running, or restarted if it is running. A timer is always started or restarted from its initial value. The initial value may be, but is not limited to be, configured by the gNB via downlink RRC signaling or be a pre-defined/pre-determined value addressed in some specifications.

PDCCH: In the downlink, the gNB may dynamically allocate resources to the UEs at least via the C-RNTI/MCS-C-RNTI/CS-RNTI on PDCCH (s) . A UE always monitors the PDCCH (s) in order to find possible assignments when its downlink reception is enabled (e.g., activities governed by the DRX when configured) . When CA is configured, the same C-RNTI applies to all serving cells. In NR wireless communication systems, a downlink data reception at the UE side is achieved by monitoring the PDCCH and finding a possible assignment. The assignment may be represented as (UE-specific) DCI. The DCI may be identified on the PDCCH via blind decoding. From the implementation of the blind decoding aspect, the UE may be configured with a set of PDCCH candidates within one or more CORESETs. The PDCCH candidate set for the UE to monitor may be defined in terms of PDCCH search space sets (or search space sets) .

A search space set may be categorized into two types (e.g., a Common Search space (CSS) set or a UE-Specific Search Space (USS) set) . That is, a UE monitors the PDCCH candidates, according to one or more configured search space sets to decode a possible PDCCH transmitted by the gNB. In other words, a PDCCH may be identified in the PDCCH candidates within the monitored search space sets. More specifically, in some implementations, the UE may monitor a set of PDCCH candidates in one or more CORESETs and/or Search Spaces on a DL BWP (e.g., the active DL BWP on each activated serving cell or the initial BWP on a camped cell) configured with the PDCCH monitoring, according to corresponding search space sets, where the monitoring implies decoding each PDCCH candidate, according to the monitored DCI formats. That is, the DCI with CRC bits scrambled by a UE-specific RNTI (e.g., C-RNTI) may be carried by the PDCCH, and the DCI may be identified by the UE descrambling the CRC bits with the RNTI.

PDSCH/PUSCH: The PDCCH may be used to schedule the DL transmissions on a PDSCH, and UL transmissions on a PUSCH.

Transport Block: The data received from the upper layer (or MAC) , for example, given to the physical layer, may be referred to as a transport block.

HARQ: A functionality that ensures the delivery between peer entities at Layer 1 (e.g., Physical Layer) . A single HARQ process supports one Transport Block (TB) when the physical layer is not configured for the downlink/uplink spatial multiplexing, and when the physical layer is configured for downlink/uplink spatial multiplexing, a single HARQ process may support one or more TBs. There is one HARQ entity per serving cell. Each HARQ entity may support a parallel (number of) DL and UL HARQ process.

Hybrid automatic repeat request acknowledgement (HARQ-ACK) : A HARQ-ACK information bit value of 0 represents a negative acknowledgement (NACK) while a HARQ-ACK information bit value of 1 represents a positive acknowledgement (ACK) .

Beam: A beam may refer to a spatial (domain) filtering. In one example, the spatial filtering is applied in the analog domain by adjusting a phase and/or amplitude of the signal before being transmitted by a corresponding antenna element. In another example, the spatial filtering is applied in the digital domain by the Multi-Input Multi-Output (MIMO) technique in the wireless communication system. For example, “aUE made a PUSCH transmission by using a specific beam” means that the UE made the PUSCH transmission by using the specific spatial/digital domain filter. The “beam” may also be, but is not limited to be, represented as an antenna, an antenna port, an antenna element, a group of antennas, a group of antenna ports, or a group of antenna elements. The beam may also be formed by a certain reference signal resource. In short, the beam may be equivalent to a spatial domain filter through which the EM wave is radiated.

A DL RRC message in the present disclosure may include, but is not limited to, an RRC reconfiguration message (RRCReconfiguration) , an RRC resume message (RRCResume) , an RRC reestablishment message (RRCReestablishment) , an RRC setup message (RRCSetup) or any other DL unicast RRC message.

A PDSCH/PDSCH/PUSCH transmission may span multiple symbols in the time domain. A time duration of a PDSCH/PDSCH/PUSCH (transmission) implies a time interval that starts from the beginning of the first symbol of the PDSCH/PDSCH/PUSCH (transmission) and ends at the end of the last symbol of the PDSCH/PDSCH/PUSCH (transmission) .

The term “ (specific) PHY layer signaling” may refer to a specific format of the DCI, a specific field of the DCI, a specific field of the DCI with the field being set to a specific value, and/or the DCI with Cyclic Redundancy Check (CRC) bits scrambled with a specific RNTI.

TCI state: A TCI state may include parameters that configure a Quasi Co-Location (QCL) relationship between one or two reference signals and a target reference signal set. For example, the target set may include the Demodulation Reference Signals (DM-RS) ports of the PDSCH, PDCCH, PUCCH, or PUSCH. The reference signals may be either UL or DL signals. In NR Releases 15 and 16, the TCI state may be utilized for DL QCL indication, while spatial relation information may provide UL spatial transmission filter information for UL signals or channels. From a UL perspective, a TCI state may offer UL beam information, potentially guiding the relationship between a UL transmission and either DL or UL reference signals, such as CSI-RS, SSB, SRS, or Phase Tracking Reference Signals (PTRS) .

When a UE moves from the coverage area of one cell to another, a change in the serving cell may be required to maintain the radio connection and quality. The change of the serving cell may be initiated by Layer 3 (L3) measurements. In addition, the change may involve a Radio Resource Control (RRC) signaling triggered reconfiguration with synchronization for the change of the Primary Cell (PCell) and the Primary Secondary Cell (PSCell) , and when applicable, for the release and addition of Secondary Cells (SCells) . All the operations described above may require a complete Layer 2 (L2) and Layer 1 (L1) resets during the L3-based mobility, which may result in longer latency, increased overhead, and extended interruption times compared to a beam switching mobility. Therefore, the objective of an L1/L2 Triggered Mobility (LTM) enhancements may include facilitating serving cell changes through the L1/L2 signaling, thus reducing latency, overhead, and interruption times.

To minimize latency and signaling overhead resulting from the L3 measurements, enhancements are necessary for the LTM. The enhancements include L1-based measurements and reporting, configuration and maintenance of multiple candidate cells, a dynamic (e.g., serving cell) switching mechanism among the candidate cells based on the L1/L2 signaling, and management of timing advance. In the present disclosure, methods and apparatus for managing measurement gap information in LTM scenarios are described, thus facilitating the measurement process by utilizing L1-based measurement gap information.

When a UE moves from the coverage area of one cell to another, a serving cell change may be required to maintain the connection and the quality of service between the serving cell and the UE. The primary aim of the L1/L2-based mobility may be to reduce mobility latency, thus necessitating support for the L1 beam management and the L1-based measurements to enhance scheduling efficiency. Specifically, the UE may receive a pre-configuration message (e.g., an RRC (reconfiguration) message) that provides information about candidate cells or at least one target cell prior to switching. The UE may then perform the cell switch based on a cell switch command, which may introduce some mobility latency.

The mobility latency may include the time from when the UE receives the cell switch command to when the UE performs the first DL reception/transmission based on the indicated beam of the target cell. Specifically, the mobility latency may include the time (e.g., handover interruption time) the UE takes to process the cell switch command (T_cmd+T_{processing, 2}) , to perform a DL synchronization (T_search+T_Δ+T_margin) , to perform a UL synchronization (T_IU+T_RAR) , and to perform the first DL reception/transmission after the Random Access Response (RAR) . Here, T_cmd may represent the time for processing L1/L2 command (s) , T_{processing, 2} may represent the time for UE processing received data after cell switch command, T_search may represent the time required to search for the target cell, T_Δ may represent the time for fine tracking and acquiring full timing information, T_margin may represent the time for SSB or CSI-RS post-processing, T_IU may represent the interruption uncertainty in acquiring the first available Physical Random Access Channel (PRACH) occasion in the target cell, and T_RAR may represent the time for RAR delay. Additionally, the decision to switch the cell may depend on L1 measurements and reports, highlighting the importance of the procedures and methods for L1 measurement and reporting.

A source cell or a base station (BS) may transmit configurations or information about candidate cells (e.g., also referred to as a pre-configuration) , to the UE via RRC signaling. Upon receiving the pre-configuration (e.g., an RRC reconfiguration message) , the UE may store and/or apply the received settings for the LTM procedure.

In some implementations, the (RRC) pre-configuration may include a resource allocation configuration (e.g., either time or frequency domain) , a DL synchronization specific configuration, a UL synchronization specific configuration, a Bandwidth Part (BWP) configuration, a cell group configuration, a measurement configuration, a report configuration, a beam management configuration (e.g., Transmission Configuration Indicator (TCI) state configuration) , a mobility scenarios configuration, a DL control channel specific configuration, a DL data channel specific configuration, a UL control channel specific configuration, and/or a UL data channel specific configuration.

In some implementations, the UE may receive (RRC) pre-configuration (s) for all candidate cells simultaneously. In some implementations, the UE may receive an (RRC) pre-configuration for each candidate cell at different times. In some implementations, the (RRC) pre-configuration may be activated/applied by an RRC reconfiguration procedure. In some implementations, the (RRC) pre-configuration may include a reference configuration and a delta configuration.

During the LTM procedure, the source cell may inform the UE of cell switching related information with a cell switch command.

In some implementations, the cell switch command may refer to a MAC-CE. In some implementations, the cell switch command may include identification (s) (ID (s) ) of candidate cell (s) (e.g., Physical Cell Identity (PCI) index/indices of candidate cell (s) , or an additional PCI index or a PCI index of the serving cell) , the ID of the target cell (e.g., a PCI index of the target cell) , RRC pre-configuration index/indices associated with the candidate cell (s) or the target cell, BWP information for the candidate cells or the target cell, TA information, associated reference signal information (e.g., SSB index/indices or CSI-RS resource index/indices) , and/or TCI state information for the candidate cell (s) or the target cell (s) . After receiving the cell switch command from the source cell, the UE may switch from the serving cell to the target cell indicated in the cell switch command.

In some implementations, the cell switching may refer to a PCell Change (e.g., switch from the source PCell to the target PCell) , an SCell change, or/and a PSCell change. Before switching, the target cell may be, for example, an SCell, a PSCell, or a non-serving cell.

During the LTM procedure, the UE may perform a DL synchronization process to acquire DL time/frequency synchronization with the target cell (s) , DL system information, and DL data from the target cell.

In some implementations, the UE may perform the DL synchronization before processing the cell switch command to reduce the interruption time. In some implementations, the UE may perform the DL synchronization after processing the cell switch command when the target cell is indicated.

In some implementations, the UE may receive information for the DL synchronization from the (RRC) pre-configuration, MAC-CE, or DCI from the source cell. In some implementations, the received information may include logical cell ID (s) (e.g., the ID (s) of the candidate cell (s) , the PCI (s) of the candidate cell (s) , the ID of the target cell, the PCI of the target cell) , the SSB index/indices associated with the candidate cell (s) , the SSB index associated with the target cell, the time/frequency domain information for the candidate cell (s) , the time/frequency domain information for the target cell, the CSI resource index/indices associated with the candidate cell (s) , the CSI resource index associated with the target cell, the TCI state configuration associated with the candidate cell (s) , and/or the TCI state configuration associated with the target cell.

During the L1/L2 triggered mobility procedure, the UE may perform a UL synchronization process to evaluate the exact timing to send UL information/data to the target cell (e.g., timing advance acquisition) .

In some implementations, the UE may perform the UL synchronization after finishing the DL synchronization process. In some implementations, the UE may perform the UL synchronization before processing the cell switch command to reduce the interruption time. In some implementations, the UE may perform the UL synchronization after processing the cell switch command when the target cell is indicated. In some implementations, the UE may perform an RA procedure (e.g., a contention-based RA procedure, a contention-free RA procedure, a 2-step RA procedure, or a 4-step RA procedure) to the candidate cell (s) or the target cell. In some implementations, the UE may perform a Random Access Channel-less (RACH-less) procedure (e.g., without performing the RA procedure) to the candidate cell (s) or the target cell.

In some implementations, the UE may receive information for UL synchronization from the (RRC) pre-configuration, MAC-CE, or DCI from the source cell. In some implementations, the received information may include the PRACH resource configuration associated with the candidate cell (s) or the target cell, the preamble sequence configuration associated with the candidate cell (s) or the target cell, the RACH procedure indication, the timing advance group index/indices associated with the candidate cell (s) or the target cell, the UL carrier types (e.g., the new uplink (NUL) or the supplementary uplink (SUL) ) for the candidate cell (s) or the target cell, the sounding reference signal (SRS) configuration associated with the candidate cell (s) or the target cell, and/or the TCI state configuration associated with the candidate cell (s) or the target cell.

The UE may perform and report an L1 measurement based on the received configuration or indication. The L1 measurement may be classified into an L1 intra-frequency measurement, or an L1 inter-frequency measurement. In some implementations, the L1 intra-frequency measurement and the L1 inter-frequency measurement may be performed based on the L1 reference signal receiving power (RSRP) by measuring the SSB (e.g., SS-RSRP) or the CSI-RS (e.g., CSI-RSRP) . In some implementations, the L1 intra-frequency measurement and the L1 inter-frequency measurement may be performed based on the L1-SINR through measuring the SSB (e.g., SS-SINR) or the CSI-RS (CSI-SINR) . In some implementations, the L1 intra-frequency measurement and the L1 inter-frequency measurement may be performed based on the L1-RSRQ through measuring the SSB (e.g., SS-RSRQ) or the CSI-RS (e.g., CSI-RSRQ) .

In some implementations, the L1 measurement report may include one or more PCIs (e.g., the PCI (s) of the candidate cell (s) , the PCI of the source cell, the PCI of the serving cell, or the PCI of the target cell) . In some implementations, the L1 measurement report may include one or more RS IDs.

In some implementations, the L1 measurement report as UCI transmitted on the PUCCH or the PUSCH may be considered as a result of measurement from the UE’s perspective. In some implementations, regarding the L1 measurement report type, the L1 measurement report may refer to a periodic report on the PUCCH, a semi-persistent report on the PUCCH or the PUSCH, and/or an aperiodic report on PUSCH. In some implementations, the L1 measurement report may be transmitted on a MAC-CE.

In some implementations, in the intra-frequency measurement scenario, the frequency of the measured RS may be covered by the active BWPs of the SpCell and the SCells configured for the UE. In some implementations, in the intra-frequency measurement scenario, the frequency of the measured RS may be covered by any of the configured BWPs of SpCell and SCells configured for the UE. In some implementations, in the intra-frequency measurement scenario, both the serving cell and candidate cell (s) (or the target cell) may correspond to the same SSB center frequency and subcarrier spacing. In some implementations, the center frequency and SCS of the neighbor cell for a SSB based intra-frequency L1 measurement configuration may be the same as the center frequency and SCS of the configured SSB of the serving cell in the ServingCellConfigCommon. In some implementations, if a bandwidth of a target cell with CSI resource (s) is within a bandwidth of the serving cell and shares the same subcarrier spacing with the bandwidth of the serving cell, the intra-frequency measurement may be applied.

In some implementations, in the inter-frequency measurement scenario, the frequency of the measured RS may not be covered by the active BWPs of the SpCell and the SCells configured for the UE In some implementations, in the inter-frequency measurement scenario, the frequency of the measured RS may not be covered by any of the configured BWPs of the SpCell and the SCells configured for the UE. In some implementations, the measurement scenarios which are the intra-frequency measurement scenario may be regarded as the inter-frequency measurement scenario.

In some implementations, the CSI report may include a Channel Quality Indicator (CQI) , a Precoding Matrix Indicator (PMI) , a CSI-RS resource indicator (CRI) , an SS/PBCH block resource indicator (SSBRI) , a Layer Indicator (LI) , a Rank Indicator (RI) , a Capability Index, an L1-RSRP, an L1-SINR, and/or an L1-RSRQ.

In some implementations, a cell in the present disclosure may refer to a PCell, a PSCell, a SpCell, an SCell, a candidate cell, a target cell, a neighboring cell, a serving cell and/or a source cell.

Inter-cell mobility scenarios may include, but not limited to, an intra-node mobility and an inter-node mobility. Moreover, each scenario may correspond to an intra-distributed unit (DU) case, an inter-DU case, an intra-central unit (CU) case, and/or an inter-CU case. It should be noted that, a network node (e.g., a BS) may include one CU and several DUs. A CU may be a logical node hosting the RRC, the service data adaptation protocol (SDAP) and the packet data convergence protocol (PDCP) protocol layers of the BS or the RRC and the PDCP protocols of the E-UTRA-NR gNB (EN-gNB) that controls the operation of one or more DUs. A DU may be a logical node hosting the radio link control (RLC) , the medium access control (MAC) and the physical (PHY) layers of the gNB or the EN-gNB, and the operation of the DU may be partly controlled by the gNB-CU. One DU may support one or more cells. The CU may connect to the DU(s) via the F1 interface (s) .

In the intra-node mobility scenario, the serving cell and the target cell may operate on the same network node and share the same MAC entity (e.g., carrier aggregation scenario) . It should be noted that, the intra-node mobility scenario may be further classified into two cases: an “intra-CU with intra-DU” case and an “intra-CU with inter-DU” case.

In the case of intra-CU with intra-DU, the serving cell and the target cell may belong to the same DU and the same CU. In the case of intra-CU with inter-DU, the serving cell and the target cell may belong to the same CU but correspond to different DUs.

In the inter-node mobility scenario, the serving cell and the target cell may operate on different network node. A UE may apply separate MAC entity to the serving cell and the target cell (e.g., dual connectivity scenario) . It should be noted that, the serving cell may refer to the special cell or the PCell, and the target cell may refer to the special cell, the PSCell, or the SCell.

In some implementations, the (RRC) pre-configuration (e.g., via RRC Reconfiguration message) may include measurement gap information.

In some implementations, the reference configuration for the LTM operation may include measurement gap information.

In some implementations, the delta configuration for the LTM operation may include measurement gap information.

In some implementations, one or more configurations may be provided for configuring the measurement gap information. In some implementations, one or more measurement gap configurations may be used to configure the measurement gap information. In other words, the measurement gap information may be included in the one or more measurement gap configurations.

In some implementations, each measurement gap configuration may correspond to a specific index. In other words, an index may be included in each measurement gap configuration.

In some implementations, the measurement gap information may be configured per cell. For example, each target cell may correspond to one measurement gap configuration. For example, the measurement gap information may correspond to the source cell. That is, during specific measurement gap (e.g., a time duration in units of milliseconds, subframes, slots, and/or symbols) determined based on the measurement gap information and the SFN of the source cell, the UE may switch to measure the reference signal (e.g., SSB, CSI-RS) of the (corresponding) target cell.

In some implementations, the measurement gap may be configured per frequency band. For example, each frequency band may correspond to one measurement gap configuration.

In some implementations, the measurement gap may be configured per frequency range. For example, when the target cell operates in a first frequency range FR1, a UE may apply the measurement gap configured for the first frequency range FR1. For example, when the target cell operates in a second frequency range FR2, a UE may apply the measurement gap configured for the second frequency range FR2.

In some implementations, the measurement gap applied may be dependent on the SCS configuration. For example, if the serving cell (e.g., the source cell) and the target cell (s) have different SCS configuration, a UE may apply the measurement gap configuration based on the cell with the smallest SCS. For example, if the serving cell and the target cell (s) have different SCS configuration, a UE may apply the measurement gap configuration based on the cell with the largest SCS.

In some implementations, the measurement gap may be configured per UE. For example, a UE may apply the same measurement gap configuration regardless of the frequency range, the SCS, and/or the number of configured cells.

In some implementations, the measurement gap may be configured per cell group.

In some implementations, the measurement gap information may be associated with an SSB identification. For example, the measurement gap configuration may be associated with the SSB to be measured (e.g., by the SSB index, the SSB position, and/or the SSB frequency) .

In some implementations, the measurement gap information may be associated with a CSI-RS identification. For example, the measurement gap configuration may be associated with a CSI-RS or tracking reference signal (TRS) identification to be measured (e.g., by the CSI-RS/TRS based mobility configuration, the CSI-RS/TRS resource index, and/or the CSI/TRS measurement configuration index) .

In some implementations, the measurement gap information may be associated with an inter-frequency-based measurement configuration. For example, the measurement gap information may be included in the inter-frequency-based measurement configuration. For example, the measurement gap configuration index may be included in the inter-frequency-based measurement configuration, and thus the UE may perform the inter-frequency-based measurement according to the associated measurement gap length value, measurement gap offset value, and/or measurement repetition value.

In some implementations, the measurement gap information may be associated with an SSB/CSI-RS/TRS based measurement configuration. For example, the measurement gap information may be included in the SSB/CSI-RS/TRS configuration.

In some implementations, the measurement object configuration may be configured to provide the target measurement object information (e.g., the target cell index, the target BWP index, the SSB frequency information, the ARFCN identity, the sub-carrier spacing information, the SSB Measurement Time Configuration (SMTC) information, the CSI-RS information, and/or the TRS information) and/or the measurement gap configuration.

In some implementations, the measurement gap information may include a measurement gap length to indicate the measurement gap length (e.g., in units of milliseconds, slots, symbols) of the measurement gap.

In some implementations, the measurement gap information may include a measurement gap repetition period (e.g., in units of milliseconds, slots, symbols) and a gap offset value to calculate the starting time of the measurement gap.

In some implementations, the measurement gap information may a measurement gap timing advance (e.g., in units of milliseconds, slots, symbols) to improve the alignment between the measurement gap and the SMTC.

In some implementations, an SMTC may correspond to a measurement gap configuration. In other words, the measurement timing offset and the duration for the target SSB may correspond to a specific measurement gap pattern (e.g., with a specific measurement gap length, a measurement gap offset, a measurement gap repetition) , then the UE may measure the SSB based on the SMTC and the associated measurement gap configuration. For example, the UE may perform an SSB measurement on the target (or candidate) cell for the inter-frequency measurement during the measurement gap, and the measurement gap may be determined by the UE based on the measurement gap information and the measurement gap configuration.

It should be noted that, the SMTC duration may be less than the duration of the measurement gap. When the measurement gap starts, the UE may spend time on radio frequency (RF) retuning to the inter-frequency SSB for the SSB measurement on the target (or candidate) cell, then start to perform the SSB measurement during the SMTC duration.

In some implementations, an SMTC may correspond to multiple measurement gap configurations. In other words, the multiple measurement gap configurations may adjust a given timing offset and the duration for the target SSB, such that there would be no conflict between the measurement gap and the SMTC (e.g., the UE may need to monitor the SSB based on the SMTC within the given measurement gap duration) .

In some examples, the corresponding measurement gap configurations for the SMTC may have different priorities. For example, each measurement gap configuration may correspond to a (priority) index, and the measurement gap configuration corresponding to the highest (priority) index may be configured if there is a conflict between multiple measurement gap configurations. For example, each measurement gap configuration may correspond to a (priority) index, and the measurement gap configuration with the lowest (priority) index may be configured if there is a conflict between multiple measurement gap configurations.

In some examples, the UE may apply the measurement gap configuration with the lowest index when one SMTC corresponds to multiple measurement gap configurations.

In some implementations, multiple SMTCs may correspond to one measurement gap configuration. Each SMTC may be associated with one target cell.

In some examples, multiple SMTCs may not configure overlapping timing of SSB for different target cells (e.g., or distinct PCIs) .

In some examples, when multiple SMTCs configure overlapping timing of SSB for different target cells, each SMTC may correspond to a (priority) index, and the SMTC corresponding to the highest (priority) index may be configured.

In some examples, when multiple SMTCs configure overlapping timing of SSB for different target cells, each SMTC may correspond to a (priority) index, and the SMTC corresponding to the lowest (priority) index may be configured.

In some examples, the SMTC corresponding to the lowest cell index may be configured.

In some implementations, the UE may measure the SSB corresponding to the SMTC with the highest priority.

In some implementations, the measurement gap information may include a reference cell, a reference SCS configuration, a reference absolute radio frequency channel number, reference SSB information, reference CSI-RS information, and/or reference TRS information.

In some implementations, the measurement gap information may include an indication which indicates a trigger of the measurement gap. The indication may be in the Boolean format or in the ENUMERATD format. For example, if the indication is set to ‘1’ , ‘true’ or ‘enable’ , a measurement gap length with a none zero value may be configured. For example, if the indication is set to ‘0’ , ‘false’ or ‘disable’ , a measurement gap length with a zero value may be configured.

In some implementations, the measurement gap information may include a gap priority index to identify the prioritized measurement gap configuration. For example, the lower gap priority index may correspond to a measurement gap configuration with a lower priority, while the higher gap priority index may correspond to a measurement gap configuration with a higher priority. Alternatively, the lower gap priority index may correspond to a measurement gap configuration with a higher priority, while the higher gap priority index may correspond to a measurement gap configuration with a lower priority.

In some implementations, only one measurement gap configuration is associated with the gap priority index, and the gap priority index may be used when multiple measurement gap configurations for multiple target (or candidate) cells provide conflicting measurement gap to the UE. The UE may use the gap priority index to determine which measurement gap configuration is to be applied.

In some implementations, only the measurement gap configuration with a specific gap priority index (e.g., “0” or “1” ) may be applied.

In some implementations, each of a list of measurement gap configurations may correspond to a gap priority index, and the gap priority index may be used to inform the UE which measurement gap configuration is to be applied first. For example, when a first measurement gap configuration corresponding to a first gap priority index (e.g., “0” ) and a second measurement gap configuration corresponding to a second gap priority index (e.g., “1” ) are configured to a UE with different measurement gap lengths and measurement gap starting points, the UE may apply the measurement gap configuration with the lower priority index (e.g., the first measurement gap configuration) . For example, when a first measurement gap configuration corresponding to a first gap priority index (e.g., “0” ) and a second measurement gap configuration corresponding to a second gap priority index (e.g., “1” ) are configured to a UE with different measurement gap lengths and measurement gap starting points, the UE may apply the measurement gap configuration with the higher priority index (e.g., the second measurement gap configuration)

In some implementations, a target (or candidate) cell may correspond to multiple measurement gap configurations. For example, a measurement gap list with multiple measurement gap configuration indices may be added to the measurement configuration for the target (or candidate) cell.

In some implementations, the measurement gap configuration indices for each configured target (or candidate) cell may have different values. For example, a first cell may be associated with a first and second measurement gap configuration indices (e.g., index#1 and index#2) and a second cell may be associated with a third measurement gap configuration index (e.g., index#3) . The first and second measurement gap configuration indices (e.g., index#1 and index#2) may not be included in the measurement gap list for the second cell.

In some implementations, the measurement gap configuration indices for each configured target (or candidate) cell may have the same value. For example, a first cell may be associated with a first and second measurement gap configuration indices (e.g., index#1 and index#2) and a second cell may be associated with the first measurement gap configuration index (e.g., index#1) .

In some implementations, one target (or candidate) cell may correspond to only one measurement gap configuration.

In some implementations, the measurement gap may be associated with a CSI report. For example, the measurement gap information may be included in a CSI report configuration.

In some implementations, measurement gap configurations may be included in a table and each entry of the table may correspond to a measurement gap configuration index. In some examples, the number of the entries in the table may not be equal to the maximum number of configured measurement gap configuration (s) . In some examples, the number of entries may be equal to a specific number (e.g., 2, 4, 8 or 16) . In some examples, the number of the entries may be equal to the maximum number of configured measurement gap configuration (s) .

In some implementations, each (RRC) pre-configuration associated with a candidate target cell may include one or more measurement gap configurations. The one or more measurement gap configurations may be associated with the measurement gap applied for the SSB measurement, the CSI measurement, and/or the measurement corresponding to different frequency bands, etc.

In some implementations, the UE may receive an RRC message with a field used to indicate whether the pre-configured measurement gap configurations (e.g., the measurement gap configurations included in the RRC pre-configuration) associated with different candidate target cells are activated or deactivated. In some implementations, the first/leftmost bit of the (RRC) field may correspond to the measurement gap configuration (s) included in a first RRC pre-configuration, the second bit may correspond to the measurement gap configuration (s) included in a second RRC pre-configuration, and so on. In some implementations, a bit with the value “0” may indicate that the corresponding pre-configured measurement gap is deactivated; and a bit with the value “1” may indicate that the corresponding pre-configured measurement gap is activated. It should be noted that, the first RRC pre-configuration may be associated with the candidate target cell with the lowest cell ID, logical ID (e.g., additionalPCIIndex) or PCI value, the second RRC pre-configuration may be associated with the candidate target cell with the second lowest cell, logical ID (e.g., additionalPCIIndex) or PCI value, and so on.

In some implementations, the UE may receive an (RRC) field included in each (RRC) pre-configuration associated with different candidate target cells, for indicating whether the pre-configured measurement gap configuration (s) included in the corresponding RRC pre-configuration is/are activated or deactivated.

In some implementations, the (RRC) pre-configuration associated with a candidate target cell may include one or more measurement gap configurations associated with different frequency bands. In addition, the (RRC) pre-configuration associated with a candidate target cell may include an (RRC) field used to indicate whether the measurement gap configuration (s) (e.g., included in the (RRC) pre-configuration) are activated or deactivated. In some implementations, the first/leftmost bit of the (RRC) field may correspond to the measurement gap configuration associated with the first frequency band, the second bit of the (RRC) field may correspond to the measurement gap configuration associated with the second frequency band, and so on. In some implementations, the bit with the value of “0” may indicate that the corresponding measurement gap configuration is deactivated, and the bit with the value of “1” may indicate that the corresponding measurement gap configuration is activated.

It should be noted that, the measurement gap configuration associated with the first frequency band may correspond to the measurement gap configuration with the lowest ID, the measurement gap configuration associated with the second frequency band may correspond to the measurement gap configuration with the second lowest ID, and so on. It should be also noted that, each measurement configuration included in an (RRC) pre-configuration may be associated with an ID.

In some implementations, a MAC CE for indicating (e.g., including) the measurement gap information may include a field corresponding to one or more measurement gap indices, and the one or more measurement gap indices may be from the (RRC) pre-configuration for LTM.

In some implementations, if one or more measurement gaps are configured for the MAC entity with the measurement gap index (e.g., by the measurement gap configuration via the RRC reconfiguration message) , the field may indicate the identity of the measurement gap for which the MAC CE applies.

In some implementations, the size of the field may be associated with the maximum number of configured measurement gap configurations.

In some implementations, the field may include multiple bits and each combination of the bits may correspond to a measurement gap index. The UE may be configured with the measurement gap configuration associated with the measurement gap index when the UE receives the RRC reconfiguration message including the measurement gap configuration.

In some implementations, the MAC CE for indicating the measurement gap information may include other information (e.g., the TCI state information) than the measurement gap information, which is not relevant to the measurement gap.

In some implementations, the MAC CE for indicating the measurement gap information may be the MAC CE for indicating all measurement information (e.g., the measurement object (e.g., including the SSB, the CSI-RS, and/or the TRS) , the measurement type (e.g., the inter-frequency and/or the intra-frequency) ) .

In some implementations, the MAC CE dedicated to indicating the measurement gap information (e.g., also referred to as the measurement gap MAC CE) may include one or more fields to indicate the measurement gap information.

In some implementations, the MAC CE dedicated to indicating the measurement gap information may refer to a measurement gap command MAC CE.

In some implementations, the MAC CE dedicated to indicating the measurement gap information may refer to an inter-frequency-based measurement command MAC CE.

In some implementations, the MAC CE dedicated to indicating the measurement gap information may include the measurement gap information only.

In some implementations, the MAC CE dedicated to indicating measurement gap information may refer to a cell switch command.

In some implementations, the cell switch command may include the measurement gap information (e.g., the measurement gap configuration index received from the (RRC) pre-configuration described above) , the measurement type (e.g., the intra-frequency-based measurement, and/or the inter-frequency-based measurement) , the logical index (e.g., the PCI) , the SSB index, the TRS index, and/or the CSI-RS index.

In some implementations, the field in the MAC CE for indicating the measurement gap information may be configured in the (RRC) pre-configuration, as described above. In addition, the MAC CE field may be further used to indicate/activate the indication provided by the RRC reconfiguration message.

In some implementations, the MAC CE may be used to activate or deactivate the measurement gap information.

In some implementations, the MAC CE may include a 1-bit field to indicate an activation of a measurement gap configuration with a bit value 1 and indicate a deactivation of the measurement gap configuration with a bit value 0. For example, if a first measurement gap configuration received via the RRC reconfiguration message (e.g., the (RRC) pre-configuration) associated with a first cell corresponds to the 1-bit field with a value of 1, a second measurement gap configuration received via the RRC reconfiguration message (e.g., the (RRC) pre-configuration) associated with the first cell corresponds to the 1-bit field with a value of 0, and a third measurement configuration received from the RRC reconfiguration message (e.g., the (RRC) pre-configuration) associated with a second cell corresponds to the 1-bit field with a value of 1, the UE may apply the measurement gap information in the first measurement gap configuration for the first cell and the measurement gap information in the third measurement gap configuration for the second cell. Each measurement gap configuration may include an associated cell index.

In some implementations, the MAC CE may include a field with log₂ (x) bits to indicate an activation of a measurement gap configuration with a corresponding index, and x may be the maximum number of the configured measurement gap configuration (s) .

In some implementations, the measurement gap configurations for different cells may be activate/deactivate by a same MAC CE, where each measurement gap configuration may include a cell index.

In some implementations, the measurement gap configuration for different cells may be activate/deactivate by different MAC CEs, where the MAC CE may include a cell index to identify the cell that the MAC CE is applied to.

In some implementations, the MAC CE for indicating the SMTC may include an SMTC index configured by the RRC reconfiguration message (e.g., or the (RRC) pre-configuration) for one or more cells.

In some implementations, the MAC CE may include a cell index, a BWP index, and/or an SSB index.

In some implementations, the MAC CE may refer to a cell switch command. In other words, the SMTC may be included in the cell switch command.

In some implementations, the MAC CE may include a periodicity, an offset value, and/or a duration value.

In some implementations, a MAC CE for indicating the measurement gap information may include one or more fields to indicate the measurement type (e.g., the intra-frequency-based measurement, the inter-frequency-based measurement, the SSB-based measurement, the CSI-RS-based measurement, and/or the TRS-based measurement) , the SSB index, the CSI-RS index, the TRS index, the CSI measurement configuration index, the CSI report configuration index, the cell index (e.g., the serving cell index, the target cell index, and/or the additional PCI index) , the BWP index and/or the TCI state information (e.g., the TCI state ID) .

In some implementations, multiple cells may correspond to a same MAC CE for indicating the measurement gap information. For example, the MAC CE may include the measurement gap information for a set of cells, and the association between the measurement gap information and the cell (e.g., a cell index) may be configured in the RRC reconfiguration message (e.g., or the (RRC) pre-configuration) . For example, the MAC CE may include the measurement gap information for a cell group, and the cells included in the cell group may be configured via the RRC signaling. For example, the MAC CE may include the measurement gap information for a group of target cells, and the group may be configured in the RRC reconfiguration message or in the MAC CE including a group of target cell indices. For example, the MAC CE may include a reference cell indicator for the gap calculations or for indicating the reference gap configuration.

In some implementations, the MAC CE for indicating the measurement gap information may be applied to one or more cells with the same frequency range (e.g., FR1 or FR2) .

In some implementations, the MAC CE for indicating the measurement gap information may be applied to the BWPs including the target measured reference signals (e.g., the SSB, the CSI-RS, or the TRS) . For example, if a first measured RS corresponding to a first cell and a second measured RS corresponding to a second cell are located in the same BWP, the first cell and the second cell may be applied with the same measurement gap information.

In some implementations, the MAC CE may include information including the measurement gap length, the measurement gap starting point, and/or the measurement gap offset.

In some implementations, the measurement gap information may correspond to an entry of a table for the measurement gap, each entry may correspond to an index, and the index may be included in the MAC CE to indicate the measurement gap information.

In some implementations, the MAC CE may include the measurement gap length value, the measurement gap offset value, and/or the measurement repetition value.

In some implementations, the DCI may include a field to indicate the measurement gap information (e.g., the measurement gap configuration index) .

In some implementations, the DCI may include a field to indicate the measurement gap length, the measurement gap starting point, and/or the measurement gap offset.

In some implementations, the DCI transmitted on the LTM-specific search space (e.g., a search space configured to a UE via the (RRC) pre-configuration for LTM) may be used to schedule PDSCH (s) carrying the cell switch command, the measurement gap information, and/or the information for the inter-frequency-based measurement.

In some implementations, the DCI transmitted on the LTM-specific CORESET (e.g., a CORESET configured to a UE in the (RRC) pre-configuration for LTM) may be used to schedule PDSCH (s) carrying the cell switch command, the measurement gap information, and/or the information for the inter-frequency-based measurement.

In some implementations, the DCI may include a field to indicate the entry in the table in the (RRC) pre-configuration.

In some implementation, DCI with CRC scrambled by a specific CRC (e.g., an RNTI for identifying LTM scheduling) may be used to schedule the measurement gap information for the inter-frequency measurement.

In some implementation, a specific DCI format (e.g., a format for identifying LTM scheduling) may be used to schedule the measurement gap information for the inter-frequency measurement.

In some implementations, the UE may perform an RS measurement based on the measurement gap information provided by the RRC message, the MAC-CE and/or the DCI to generate a measurement report for the LTM.

For example, the UE may perform the inter-frequency measurement on the RS (e.g., the SSB, the CSI-RS, and/or the TRS) of the candidate cells within the measurement gap based on the measurement gap information.

In some implementations, the UE may report a UE capability of whether to require the measurement gap information to a BS, to receive the corresponding signaling (e.g., the measurement gap information) .

In some implementations, the UE may receive, from a BS, an RRC message (e.g., an RRC pre-configuration, an RRC reconfiguration, an RRC configuration) , a MAC-CE, and/or DCI including the measurement gap information.

In some implementations, the received RRC message, MAC-CE, and/or DCI may be used to indicate the measurement timing to the UE.

In some implementations, the UE may receive an RRC message, a MAC-CE, and DCI in a predetermined order.

In some implementations, the UE may receive an RRC message first and receive a MAC CE (e.g., an activation command, a cell switch command, etc. ) after receiving the RRC message.

In some implementations, the UE may receive an RRC message first and receive DCI after receiving the RRC message.

In some implementations, the UE may receive a MAC CE first and receive DCI after receiving the MAC CE.

In some implementations, the UE may receive an RRC message first, receive a MAC CE after receiving the RRC message, and then receive DCI after receiving the MAC CE.

In some implementations, the UE may receive the MAC CE for indicating the measurement gap, and the cell switch command, separately. For example, the UE may receive the MAC CE for indicating the measurement gap first, and then receive the cell switch command. For example, the UE may receive the cell switch command first, and then receive the MAC CE for indicating the measurement gap.

In some implementations, the UE may receive an (RRC) pre-configuration first and then receive an RRC configuration.

In some implementations, the UE may receive an RRC message for the serving cell before receiving an RRC message for at least one candidate cell.

In some implementations, the UE may receive an RRC message for the serving cell and an RRC message for at least one candidate cell simultaneously.

In some implementations, the UE may receive an RRC message for at least one candidate cell before receiving the cell switch command.

In some implementations, the UE may receive an RRC message for at least one candidate cell after receiving the cell switch command.

In some implementations, the UE may receive an RRC message for at least one candidate cell and the cell switch command simultaneously.

In some implementations, the UE may receive an RRC message for at least one candidate cell, the cell switch command, and the MAC CE for indicating the measurement gap simultaneously.

In some implementations, the UE may transmit a report for the intra-frequency measurement based on a given measurement gap to the BS.

In some implementations, the UE may transmit a report for the inter-frequency measurement based on a given measurement gap to the BS.

In some implementations, the UE may transmit a report including the measurement result for the intra-frequency measurement and the inter-frequency measurement to the BS.

In some implementations, when a UE receives the measurement gap information via an RRC signaling, a MAC CE, or DCI, the UE may apply the measurement gap information to the inter-frequency-based measurements. For example, the UE may measure the target RS (e.g., the SSB, the CSI-RS, and/or the TRS) on the target BWP. The target RS may be measured in a time duration which is apart from the given starting point and a specific period of time according to the measurement gap length value, measurement gap offset value, and measurement gap repetition value.

In some implementations, the UE may receive the SSB configuration, the CSI-RS configuration or the TRS configuration to determine the target RS according to the given frequency and time allocation, measurement periodicity, and/or measurement duration in the SSB configuration, the CSI-RS configuration or the TRS configuration.

In some implementations, the UE may receive the measurement configuration to perform an inter-frequency-based measurement based on the SSB, the CSI-RS, or the TRS. The SSB, the CSI-RS, or the TRS of the target cell may have different center frequency and SCS from the SSB, the CSI-RS, or the TRS of the serving cell.

In some implementations, the BS may transmit a measurement signaling including the measurement gap information (or the measurement configuration) provided by the RRC message, the MAC-CE and/or the DCI, to inform the UE to perform the measurement for LTM.

In some implementations, the BS may transmit a report signaling (or a report configuration) provided by the RRC message, the MAC-CE and/or the DCI, to inform the UE to generate the report for LTM.

In some implementations, the BS may receive a UE capability of whether to require the measurement gap information from the UE to transmit the corresponding signaling.

In some implementations, the BS may transmit an RRC message (e.g., an RRC pre-configuration, an RRC reconfiguration, or an RRC configuration) , a MAC-CE, and/or DCI including the measurement gap information to the UE.

In some implementations, the transmitted RRC message, MAC-CE, and/or DCI may be used to indicate the measurement gap configuration for the intra-frequency measurement.

In some implementations, the transmitted RRC message, MAC-CE, and/or DCI may be used to indicate the measurement gap configuration for the inter-frequency measurement.

In some implementations, the transmitted RRC message, MAC-CE, and/or DCI may be used to indicate the report configuration for the intra-frequency measurement.

In some implementations, the transmitted RRC message, MAC-CE, and/or DCI may be used to indicate the report configuration for the inter-frequency measurement.

In some implementations, the BS may transmit an RRC message, a MAC-CE, and DCI in a predetermined order.

In some implementations, the BS may transmit an RRC message first and transmit a MAC CE after transmitting the RRC message.

In some implementations, the BS may transmit an RRC message first and transmit DCI after transmitting the RRC message.

In some implementations, the BS may transmit a MAC CE message first and transmit DCI after transmitting the MAC CE.

In some implementations, the BS may transmit an RRC message first, transmit a MAC CE after transmitting the RRC message, and then transmit DCI.

In some implementations, the BS may transmit the MAC CE for indicating measurement gap information, and the cell switch command, separately. For example, the BS may transmit the MAC CE for indicating the measurement gap first, and then transmit the cell switch command. For example, the BS may transmit the cell switch command first, and then transmit the MAC CE for indicating the measurement gap.

In some implementations, the BS may transmit an (RRC) pre-configuration first and then transmit an RRC configuration.

In some implementations, the BS may transmit an RRC message for the serving cell before an RRC message for at least one candidate cell.

In some implementations, the BS may transmit an RRC message for the serving cell and an RRC message for at least one candidate cell simultaneously.

In some implementations, the BS may transmit an RRC message for at least one candidate cell before transmitting the cell switch command.

In some implementations, the BS may transmit an RRC message for at least one candidate cell after transmitting the cell switch command.

In some implementations, the BS may transmit an RRC message for at least one candidate cell and the cell switch command simultaneously.

In some implementations, the BS may transmit an RRC message for at least one candidate cell, the cell switch command, and the MAC CE for indicating the measurement gap simultaneously.

In some implementations, the BS may receive a report for the intra-frequency measurement based on the given measurement gap information from one or more UEs.

In some implementations, the BS may receive a report for the inter-frequency measurement based on the given measurement gap information from one or more UEs.

In some implementations, the BS may receive a report for the intra-frequency measurement and the inter-frequency measurement based on the given measurement gap information from one or more UEs.

FIG. 1 is a flowchart for a method/process 100 for LTM, according to an example implementation of the present disclosure. In some embodiment the process 100 may be performed by a UE. It should be noted that although actions 102, 104, and 106 are illustrated as separate actions represented as independent blocks in FIG. 1, these separately illustrated actions should not be construed as necessarily order-dependent. Unless otherwise indicated, the order in which the actions are performed in FIG. 1 is not intended to be construed as a limitation, and any number of the disclosed blocks may be combined in any order to implement the method, or an alternate method. Moreover, each of actions 102, 104, and 106 may be performed independently of other actions and may be omitted in some implementations of the present disclosure.

Referring to FIG. 1, in action 102, the process 100 may start by receiving an RRC message which includes one or more measurement gap configurations and an index for each of the one or more measurement gap configurations. For example, the UE may receive an RRC reconfiguration message from a BS.

In some implementations, each of the one or more measurement gap configurations may be associated with an SSB resource or a CSI-RS resource.

In some implementations, the RRC (reconfiguration) message may further include a measurement gap length (e.g., in units of symbols) , a measurement gap offset, measurement repetition information, a reference cell, reference SSB information, and reference CSI-RS information, for each of the one or more measurement gap configurations.

In some implementations, the one or more measurement gap configurations is configured per frequency band. Specifically, each of the one or more measurement gap configurations may be associated with a frequency band. In other words, each of the one or more measurement gap configurations may be configured to be applied to the frequency band.

Referring back to FIG. 1, in action 104, the process 100 may receive a MAC CE including a first field which indicates one of the one or more measurement gap configurations using the index. For example, the UE may receive the MAC CE from the BS.

In some implementations, the received MAC CE may further include a second field which indicates an SSB index or a CSI-RS index. The SSB index or the CSI-RS index indicated by the second field may be associated with the one of the one or more measurement gap configurations indicated by the first field of the MAC CE.

In some implementations, the received MAC CE may include a cell switch command.

Referring back to FIG. 1, in action 106, the process 100 may perform an inter-frequency-based measurement based on the one of the one or more measurement gap configurations. The process 100 may then end.

In some implementations, the UE may perform the inter-frequency-based measurement based on the measurement gap length, the measurement gap offset, and/or the measurement repetition information associated with the one of the one or more measurement gap configurations.

In some implementations, the UE may perform the inter-frequency-based measurement based on the SSB resource, or the SSB index, associated with the one of the one or more measurement gap configurations.

In some implementations, the UE may perform the inter-frequency-based measurement based on the CSI-RS resource, or the CSI-RS index, associated with the one of the one or more measurement gap configurations.

In some implementations, after performing the inter-frequency-based measurement, the UE may switch to a target cell based on a measurement result of the inter-frequency-based measurement.

FIG. 2 is a block diagram illustrating a node 200 for wireless communication, according to an example implementation of the present disclosure. As illustrated in FIG. 2, a node 200 may include a transceiver 220, a processor 228, a memory 234, one or more presentation components 238, and at least one antenna 236. The node 200 may also include a radio frequency (RF) spectrum band module, a BS communications module, a NW communications module, and a system communications management module, Input /Output (I/O) ports, I/O components, and a power supply (not illustrated in FIG. 2) .

Each of the components may directly or indirectly communicate with each other over one or more buses 240. The node 200 may be a UE or a BS that performs various functions disclosed with reference to FIG. 1.

The transceiver 220 has a transmitter 222 (e.g., transmitting/transmission circuitry) and a receiver 224 (e.g., receiving/reception circuitry) and may be configured to transmit and/or receive time and/or frequency resource partitioning information. The transceiver 220 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 220 may be configured to receive data and control channels.

The node 200 may include a variety of computer-readable media. Computer-readable media may be any available media that may be accessed by the node 200 and include volatile (and/or non-volatile) media and removable (and/or non-removable) media.

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.

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.

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 NW or direct-wired connection, and wireless media, such as acoustic, RF, infrared, and other wireless media. Combinations of any of the previously listed components should also be included within the scope of computer-readable media.

The memory 234 may include computer-storage media in the form of volatile and/or non-volatile memory. The memory 234 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. 2, the memory 234 may store a computer-readable and/or computer-executable instructions 232 (e.g., software codes or programs) that are configured to, when executed, cause the processor 228 to perform various functions disclosed herein, for example, with reference to FIG. 1. Alternatively, the instructions 232 may not be directly executable by the processor 228 but may be configured to cause the node 200 (e.g., when compiled and executed) to perform various functions disclosed herein.

The processor 228 (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 228 may include memory. The processor 228 may process the data 230 and the instructions 232 received from the memory 234, and information transmitted and received via the transceiver 220, the baseband communications module, and/or the NW communications module. The processor 228 may also process information to send to the transceiver 220 for transmission via the antenna 236 to the NW communications module for transmission to a Core Network (CN) .

One or more presentation components 238 may present data indications to a person or another device. Examples of presentation components 238 may include a display device, a speaker, a printing component, a vibrating component, etc.

In view of the present disclosure, 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 considered in all respects as illustrative and not restrictive. It should also be understood that the present disclosure is not limited to the specific implementations disclosed. Still, many rearrangements, modifications, and substitutions are possible without departing from the scope of the present disclosure.

Claims

A method for Layer 1/Layer 2 (L1/L2) Triggered Mobility (LTM) performed by a user equipment (UE) , the method comprising:

receiving a Radio Resource Control (RRC) reconfiguration message, the RRC reconfiguration message comprising one or more measurement gap configurations and an index for each of the one or more measurement gap configurations;

receiving a Medium Access Control (MAC) Control Element (CE) , the MAC CE comprising a first field indicating one of the one or more measurement gap configurations using the index; and

performing an inter-frequency-based measurement based on the one of the one or more measurement gap configurations, wherein

each of the one or more measurement gap configurations is associated with a Synchronization Signal Block (SSB) resource or a Channel State Information-Reference Signal (CSI-RS) resource.
The method of claim 1, further comprising:

switching to a target cell based on a measurement result of the inter-frequency-based measurement.
The method of claim 1, wherein the RRC reconfiguration message further comprises a measurement gap length, a measurement gap offset, measurement repetition information, a reference cell, reference SSB information, and reference CSI-RS information, for each of the one or more measurement gap configurations.
The method of claim 3, wherein the measurement gap length is in units of symbols.
The method of claim 1, wherein each of the one or more measurement gap configurations is configured to be applied to a frequency band.
The method of claim 1, wherein the MAC CE further comprises a cell switch command.
The method of claim 1, wherein the MAC CE further comprises a second field indicating an SSB index or a CSI-RS index, and the SSB index or the CSI-RS index indicated by the second field is associated with the one of the one or more measurement gap configurations indicated by the first field.
A user equipment (UE) , comprising:

one or more processors; and

at least one non-transitory computer-readable medium coupled to at least one of the one or more processors and storing one or more computer-executable instructions that, when executed by the at least one of the one or more processors, cause the UE to:

receive a Radio Resource Control (RRC) reconfiguration message, the RRC reconfiguration message comprising one or more measurement gap configurations and an index for each of the one or more measurement gap configurations;

receive a Medium Access Control (MAC) Control Element (CE) , the MAC CE comprising a first field indicating one of the one or more measurement gap configurations using the index; and

perform an inter-frequency-based measurement based on the one of the one or more measurement gap configurations, wherein

each of the one or more measurement gap configurations is associated with a Synchronization Signal Block (SSB) resource or a Channel State Information-Reference Signal (CSI-RS) resource.
The UE of claim 8, wherein the one or more computer-executable instructions, when executed by the at least one of the one or more processors, further cause the UE to:

switch to a target cell based on a measurement result of the inter-frequency-based measurement.
The UE of claim 8, wherein the RRC reconfiguration message further comprises a measurement gap length, a measurement gap offset, measurement repetition information, a reference cell, reference SSB information, and reference CSI-RS information, for each of the one or more measurement gap configurations.
The UE of claim 10, wherein the measurement gap length is in units of symbols.
The UE of claim 8, wherein each of the one or more measurement gap configurations is configured to be applied to a frequency band.
The UE of claim 8, wherein the MAC CE further comprises a cell switch command.
The UE of claim 8, wherein the MAC CE further comprises a second field indicating an SSB index or a CSI-RS index, and the SSB index or the CSI-RS index indicated by the second field is associated with the one of the one or more measurement gap configurations indicated by the first field.