Methods and apparatuses for network optimization

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). A method performed by a User Equipment (UE) (302) for network optimization is disclosed. The method includes performing (804) Layer 1 (L1) measurements associated with one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells. Further, the method includes detecting (806) at least one of a mobility event or a failure event. Furthermore, the method includes transmitting (808), to a network entity (304), a report based on the detection. The report comprises one or more of the L1 measurements, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements.

Description

METHODS AND APPARATUSES FOR NETWORK OPTIMIZATION

[0001] The present disclosure generally relates to field of wireless communication networks. More particularly, the present disclosure relates to methods and apparatuses for network optimization

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] The present invention has been made to address at least the above problems and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention provides a method and apparatus for network optimization.

[0009] This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention nor is it intended for determining the scope of the invention.

[0010] According to an embodiment of the present disclosure, a method performed by a User Equipment (UE) for network optimization is disclosed. The method includes performing Layer 1 (L1) measurements associated with one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells. Further, the method includes detecting at least one of a mobility event or a failure event. Furthermore, the method includes transmitting, to a network entity, a report based on the detection. The report comprises one or more of the L1 measurements, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements.

[0011] According to another embodiment of the present disclosure, a method performed by a network entity for network optimization is disclosed. The method includes receiving, from a User Equipment (UE), a report. The report comprises one or more of Layer 1 (L1) measurements corresponding to each of one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells corresponding to the UE, and the PCI and a channel frequency number corresponding to the L1 measurements. Further, the method includes mapping the L1 measurements to one of the one or more LTM candidate cells based on the report for network optimization.

[0012] According to yet another embodiment of the present disclosure, a User Equipment (UE) for network optimization is disclosed. The UE includes a memory and a processor operatively coupled to the memory. The processor is configured to perform Layer 1 (L1) measurements associated with one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells. The processor is also configured to detect at least one of a mobility event or a failure event. The processor is further configured to transmit, to a network entity, a report based on the detection. The report comprises one or more of the L1 measurements, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements.

[0013] According to an embodiment of the present disclosure, a network entity for network optimization is disclosed. The network entity includes a memory and a processor operatively coupled to the memory. The processor is configured to receive, from a User Equipment (UE), a report. The report comprises one or more of Layer 1 (L1) measurements corresponding to each of one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells corresponding to the UE, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements. The processor is also configured to map the L1 measurements to one of the one or more LTM candidate cells based on the report for network optimization.

[0014] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

[0015] In accordance with an aspect of the disclosure, a method performed by a user equipment is provided. The method includes receiving, from a base station, a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information; based on the LTM configuration information, performing an L1 measurement; and in case that a radio link failure (RLF) for the LTM is detected, transmitting, to a base station, a RLF report, wherein the RLF report includes first L1 measurement result information associated with the LTM.

[0016] In accordance with an aspect of the disclosure, a method performed by a base station is provided. The method includes transmitting, to a user equipment (UE), a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information, wherein an L1 measurement is performed based on the LTM configuration information; and in case that a radio link failure (RLF) for the LTM is detected, receiving, from the UE, a RLF report, wherein the RLF report includes first L1 measurement result information associated with the LTM.

[0017] In accordance with an aspect of the disclosure, a user equipment is provided. The UE comprisisng: a transceiver, and a controlled coupled with the transceiver, and configured to: receive, from a base station, a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information, based on the LTM configuration information, perform an L1 measurement, and in case that a radio link failure (RLF) for the LTM is detected, transmit, to a base station, a RLF report, wherein the RLF report includes first L1 measurement result information associated with the LTM.

[0018] In accordance with an aspect of the disclosure, a base station is provided. The base station comprisisng: a transceiver, and a controlled coupled with the transceiver, and configured to: transmit, to a user equipment (UE), a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information, wherein an L1 measurement is performed based on the LTM configuration information, and in case that a radio link failure (RLF) for the LTM is detected, receive, from the UE, a RLF report, wherein the RLF report includes first L1 measurement result information associated with the LTM.

[0019] Advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. For more enhanced communication system, there is a need for optimizaing a network.

[0020] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0021] Figure 1 illustrates an exemplary configuration, according to existing techniques;

[0022] Figure 2 illustrates an exemplary successful PSCell report (SPR), according to existing techniques;

[0023] Figure 3 illustrates a block diagram depicting an environment for network optimization, in accordance with an embodiment of the present disclosure;

[0024] Figure 4 illustrates a flowchart depicting a method of reporting Lower layers (L1 / L2 layers) Triggered Mobility (LTM) measurements for Self-Organizing Networks (SON) / Minimization of Drive Tests (MDT), according to an embodiment of the present disclosure;

[0025] Figure 5 illustrates a flowchart depicting a method of logging conditional LTM information for SON / MDT, according to an embodiment of the present disclosure;

[0026] Figure 6 illustrates a flowchart depicting a method of logging conditional early synchronisation information for SON / MDT, according to an embodiment of the present disclosure;

[0027] Figure 7 illustrates an exemplary reporting of LTM measurements in SON / MDT report, according to an embodiment of the present disclosure;

[0028] Figure 8 illustrates a flowchart depicting a method performed by a User Equipment (UE) for the network optimization, in accordance with an embodiment of the present disclosure;

[0029] Figure 9 illustrates a flowchart depicting a method performed by a network entity for the network optimization, in accordance with an embodiment of the present disclosure;

[0030] Figure 10 illustrates an example block diagram of the UE, in accordance with an embodiment of the present disclosure; and

[0031] Figure 11 illustrates an example block diagram of the network entity, in accordance with an embodiment of the present disclosure.

[0032] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale.

[0033] Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0034] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the various embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

[0035] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.

[0036] Whether or not a certain feature or element was limited to being used only once, it may still be referred to as "one or more features" or "one or more elements" or "at least one feature" or "at least one element." Furthermore, the use of the terms "one or more" or "at least one" feature or element does not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, "there needs to be one or more쪋" or "one or more elements is required."

[0037] Reference is made herein to some "embodiments." It should be understood that an embodiment is an example of a possible implementation of any features and / or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and / or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.

[0038] Use of the phrases and / or terms including, but not limited to, "a first embodiment," "a further embodiment," "an alternate embodiment," "one embodiment," "an embodiment," "multiple embodiments," "some embodiments," "other embodiments," "further embodiment", "furthermore embodiment", "additional embodiment" or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and / or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and / or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and / or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and / or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[0039] Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

[0040] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[0041] Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

[0042] The present invention addresses issues such as the reporting of Layer 1 (L1) measurements logged by a User Equipment (UE) for a serving cell, a target cell, and other Lower Layers (L1 / L2 layers) Triggered Mobility (LTM) candidate cells during a failure event or a mobility event. The failure event may include, but is not limited to, a Radio Link Failure (RLF), a HO failure, an LTM cell switch failure, or a Secondary Cell Group (SCG) Failure. The mobility event may include, but is not limited to, one or more of an LTM cell switch, a Successful Handover (SHO), a successful Primary Secondary Cell (PSCell) addition, a successful PScell change, and the like.

[0043] The present invention also provides a method by which a network maps the reported L1 measurements for the LTM candidate cells to the correct candidate cell.

[0044] In addition, the present invention describes techniques using which the UE reports a time elapsed between the failure event (e.g., the RLF or Secondary Cell Group (SCG) failure) and either a successful Master Cell Group (MCG) or a SCG LTM cell switch. The present invention also provides a time elapsed between a configuration of LTM settings and an execution of an LTM cell switch. Furthermore, the present invention addresses the technical problems associated with an optimization of a conditional early synchronization.

[0045] Further, the present disclosure discloses that the UE reports Layer 1 (L1) measurements for LTM, including information to map the L1 measurements to the corresponding LTM candidate cells in Self-Organizing Network (SON) / Minimization of Drive Tests (MDT) reports such as Radio Link Failure (RLF) report, Successful Handover Report (SHR), Successful PSCell Addition or Change Report (SPR), and in the Secondary Cell Group Failure Information (SCGFailureInformation). The UE includes the LTM candidate identifier (e.g., ltm-CandidateId-r18 in New Radio (NR)) in these reports, along with the L1 measurements for the LTM, to facilitate mapping to the correct candidate cell. Additionally, the UE includes Cell Global Identity (CGI) information (e.g., CGI-Info-Logging-r16 in NR) of the LTM candidate cells in the reports, allowing the serving cell to identify neighbor cells even when multiple neighbors have the same Physical Cell Identity (PCI) and frequency. This also permits later retrieval and processing of neighbor cell information, as candidate identifiers may be reallocated to different cells over time.

[0046] The UE further includes the NR Cell Global Identifier (NCGI) of the LTM candidate cells in the reports for accurate mapping. If the LTM candidate cell is an inter-Next Generation Node B (inter-gNB) (inter-Central Unit (inter-CU)) cell, the UE includes CGI information; otherwise, the UE may not include the CGI information. Moreover, the UE provides the physical cell identity and carrier frequency number of the LTM candidate cells in the reports to assist in distinguishing between neighbors with the same PCI and frequency, based on deployment maps or other network factors.

[0047] The information in this section merely provides background information related to the present disclosure and may not constitute prior art(s) for the present disclosure.

[0048] Layer 1 / Layer 2 Triggered Mobility (LTM) solves problems of latency and signalling overhead associated with Layer 3 (L3) mobility. The goal of the LTM is to enable a serving cell to change through L1 / L2 layers signalling in order to reduce the latency, overhead, and interruption time.

[0049] A network (e.g., a Next Generation Node B (gNB)) configures a User Equipment (UE) with multiple candidate cells to allow fast application of configurations for the multiple candidate cells.

[0050] Figure 1 illustrates an exemplary configuration 100, according to existing techniques. The configuration 100 is in accordance with a Third Generation Partnership Project (3GPP) specification. The exemplary configuration 100 may be sent by a network entity to a User Equipment (UE).

[0051] Further, the network transmits Medium Access Control (MAC) Control Elements (CE) or L1 layer signaling to dynamically switch the UE from a source cell to one of the multiple candidate cells. Furthermore, the LTM can be initiated based on L1 layer measurements rather than L3 layer measurements. For beam selection using a Synchronization Signal Block (SSB) based L1-Reference Signal Received Power (RSRP) measurement report in the context of the LTM, the UE reports L*M values, where L represents a number of cells and M represents a number of beams.

[0052] - For the value of M, L

[0053] - A Radio Resource Control (RRC) configured candidate values are:

[0054] - M = 1, 2, 3, 4

[0055] - L = 1, 2, 3, 4

[0056] Details from the 3GPP Technical Specification (TS) 38.212 are given below:

[0057] While reporting the L1 measurements, the UE includes the Synchronization Signal-Reference Signal Received Power (SS-RSRP) for the L1 measurements for Synchronization Signal Block Reference Index#1 (SSBRI#1) and differential RSRP for the remaining entries, as defined in Table-1 provided below.

[0058]

[0059] Table 1

[0060] Further, the maximum value of M*L and the combination of M and L are up to the capability of the UE. The reporting range of the SS-RSRP and Channel State Information Reference Signal Received Power (CSI-RSRP) for L1 reporting is defined from -140 to -44　dBm with 1　dB resolution. The reporting range of differential SS-RSRP and the CSI-RSRP for the L1 reporting and L3 reporting is defined from 0 dB to -30 dB with 2　dB resolution.

[0061] The reporting range when an absolute RSRP range reporting is used is defined in Table 2 provided below. As shown in Table 2, when the absolute RSRP range reporting is performed, the UE reports an integer value corresponding to the measured L3 RSRP or measured L1 RSRP. If the measured L1 RSRP is less than -140 dBm, while reporting the absolute RSRP range, the UE reports RSRP_16. If the measured L1 RSRP is greater than or equal to -140 dBm and less than -139 dBm, while reporting the absolute RSRP range, the UE reports RSRP_17. If the measured L1 RSRP is greater than or equal to -139 dBm and less than -138 dBm, while reporting the absolute RSRP range, the UE reports RSRP_18. If the measured L1 RSRP is greater than or equal to -138 dBm and less than -137 dBm, while reporting the absolute RSRP range, the UE reports RSRP_19.

[0062]

[0063]

[0064] Table 2: SS-RSRP and CSI-RSRP measurement report mapping (Absolute RSRP range reporting)

[0065] Table 3 illustrates an example of differential RSRP range reporting. Further, a mapping of measured quantity is defined in Table 3 provided below. The range in the signalling is larger than the guaranteed accuracy range.

[0066]

[0067] Table 3: Differential SS-RSRP and CSI-RSRP measurement (for L1 reporting and L3 reporting) report mapping

[0068] The 3GPP proposes to perform the LTM, without reset of lower layers like MAC to avoid data loss and to reduce the additional delay of data recovery wherever it is possible. A detailed description of the LTM from 3GPP specifications is given below.

[0069] The LTM is a procedure in which a gNB receives L1 measurement report(s) from the UE, and on basis of the received L1 measurement report(s), the gNB changes the UE's serving cell by a cell switch command signalled via the MAC CE. The cell switch command indicates an LTM candidate cell configuration that the gNB previously prepared and provided to the UE through RRC signalling. Then, the UE switches to a target cell according to the cell switch command. The LTM procedure can be used to reduce mobility latency.

[0070] The network requests the UE to perform early Timing Advance (TA) acquisition of a candidate cell before a cell switch. The network indicates in the cell switch command whether the UE is required to access the target cell with a Random Access (RA) procedure if a TA value is not provided or with a Physical Downlink Control Channel (PDCCH) transmission using the TA value. For a Random Access Channel (RACH)-less LTM, the UE either monitors a PDCCH for dynamic scheduling from the target cell upon a LTM cell switch, or the UE selects a configured grant occasion associated with a beam indicated in the cell switch command.

[0071] The following principles apply to the LTM:

[0072] - The UE does not update a security key in the LTM.

[0073] - Subsequent LTM is supported.

[0074] The LTM supports an intra-Next Generation NodeB - Distributed Unit (intra-gNB-DU), an intra-gNB-Control Unit (CU), and an inter-gNB-DU mobility. The LTM also supports inter-frequency mobility, including mobility to an inter-frequency cell that is not a current serving cell. The following scenarios are supported:

[0075] - Primary Cell (PCell) change in a non-Carrier Aggregation (CA) scenario,

[0076] - PCell change in a CA scenario,

[0077] - Dual connectivity scenario, at least for a Primary Secondary Cell (PSCell) change without a Master Node (MN) involvement case, i.e., intra-Secondary Node (intra-SN) PSCell change.

[0078] The cell switch command is conveyed in the MAC CE, which contains the necessary information to perform the LTM cell switch. Furthermore, the LTM cell switch execution is provided below:

[0079] Upon the indication by the lower layers that an LTM cell switch procedure is triggered, or upon performing the LTM cell switch following cell selection performed while a timer is running, as specified in the 3GPP specifications, the UE is required to:

[0080] 1> if the LTM cell switch is triggered on a Master Cell Group (MCG):

[0081] 2> release / clear all current dedicated and common radio configurations which have not been received either via a Signaling Radio Bearer 1 (SRB1) within mrdc-SecondaryCellGroup, or via SRB3 except for the following:

[0082] - the radio bearer configuration (configured via RadioBearerConfig)

[0083] - the logicalChannelIdentity and logicalChannelIdentityExt of Radio Link Control (RLC) bearers configured in RLC-BearerConfig and the associated RLC entities, their state variables, buffers, and timers;

[0084] - the UE variables VarLTM-ServingCellNoResetID and VarLTM-ServingCellUE-MeasuredTA-ID;

[0085] - the ltm-Config;

[0086] - the Master Cell Group - Cell Radio Network Temporary Identifier (MCG C-RNTI);

[0087] - Access Stratum (AS) security configurations associated with a master key;

[0088] 1> else, if the LTM cell switch is triggered on a Secondary Cell Group (SCG):

[0089] 2> release / clear all current dedicated and common radio configurations which have been received either via the SRB1 within mrdc-SecondaryCellGroup, or via SRB3, except for the following:

[0090] - the radio bearer configuration (configured via RadioBearerConfig IE)

[0091] - the logicalChannelIdentity and logicalChannelIdentityExt of RLC bearers configured in RLC-BearerConfig and the associated RLC entities, their state variables, buffers, and timers;

[0092] - the UE variables VarLTM-ServingCellNoResetID and VarLTM-ServingCellUE-MeasuredTA-ID;

[0093] - the ltm-Config;

[0094] - the AS security configurations associated with the secondary key;

[0095] 1> for each SRB / Data Radio Bearer (DRB) in the current UE configuration:

[0096] 2> if the LTM cell switch is triggered on the MCG and the SRB / DRB using the master key; or

[0097] 2> if the LTM cell switch is triggered on the SCG and the SRB / DRB using the secondary key:

[0098] 3> keep the associated Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP) entities, their state variables, buffers and timers;

[0099] 3> release all fields related to the SRB / DRB configuration except for srb-Identity and drb-Identity;

[0100] 1> apply the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in System Information Block 1 (SIB1);

[0101] 1> use the default values specified in the 3GPP specifications for timers T310, T311 and constants N310, N311 associated with the cell group for which the LTM cell switch procedure is triggered;

[0102] 1> apply the default MAC Cell Group configuration as specified in the 3GPP specifications for the cell group for which the LTM cell switch procedure is triggered;

[0103] <various other steps for the LTM cell switch>

[0104] A Successful Handover Report (SHR) gives the network awareness of information when a handover is successful. For instance, giving the network information even when the handover is successful, even though the handover is successful does not mean that the handover is entirely unproblematic, as the handover takes a long time to complete. The network configures the UE with certain conditions, and if the conditions are fulfilled, the UE logs into the SHR.

[0105] The SHR contains the following information:

[0106] - Source and target cell information;

[0107] - Measurement of neighbouring cells;

[0108] - UE location information;

[0109] - Time since Conditional Handover (CHO) reconfiguration;

[0110] - SHR cause - T304, T310, T312. The SHR tells the network the reason why the SHR is triggered. The triggering may be based on the timer elapsed more than a certain percentage;

[0111] - Random access information;

[0112] - User plane interruption time during the handover;

[0113] - C-RNTI;

[0114] - Evolved Universal Terrestrial Radio Access (E-UTRA) information such as target cell ID and E-UTRA C-RNTI; and

[0115] - Time since the SHR.

[0116] Further, the conditions for logging into the SHR include:

[0117] a. T310 threshold (thresholdPercentageT310 in NR): the T310 threshold indicates a threshold for the ratio in percentage between an elapsed T310 timer and a configured value of a T310 timer. Detailed behavior may be found in the 3GPP specifications.

[0118] b. T312 threshold (thresholdPercentageT312 in NR): the T312 threshold indicates a threshold for the ratio in percentage between an elapsed T312 timer and a configured value of a T312 timer. Detailed behavior may be found in the 3GPP specifications.

[0119] c. T304 threshold (thresholdPercentageT304 in NR): the T304 threshold field indicates a threshold for the ratio in percentage between an elapsed T304 timer and a configured value of a T304 timer. Detailed behavior may be found in the 3GPP specifications.

[0120] d. the T310 threshold, the T312 threshold and the T304 threshold are applicable for the LTM. The UE logs the SHR if the ratio in percentage between the elapsed T310 timer / T312 timer / T304 timer and the configured value of the T310 timer / T312 timer / T304 timer is greater than the T310 threshold, T312 threshold, and T304 threshold configured for the LTM during the LTM cell switch triggered by the network.

[0121] Additionally, the SHR for the LTM is based on the following conditions:

[0122] - TA validation time-related triggering condition;

[0123] - Interruption time-related triggering condition;

[0124] - L1 measurement result validation related triggering condition;

[0125] - Random Access (RA) based cell switch: the UE logs the SHR for the LTM if the cell switch is the RA based cell switch; and

[0126] - Fallback from RACH-less LTM to RACH-based LTM. The UE logs the SHR for the LTM if there is a fallback from RACH less cell switch to RACH-based LTM cell switch.

[0127] The successful handover report (SHR) gives the network awareness of information when a handover is successful. This may for instance give the network information potential information even when a handover is successful, as even though a handover is successful does not mean that it is entirely unproblematic as the handover may take a long time to complete.

[0128] Further, to detect a sub-optimal successful PSCell change or sub-optimal successful Primary Secondary (PS) cell addition event, the UE reports information related to successful PSCell Addition and Successful PSCell Change. The information is to be stored and reported in a report called Successful PSCell Report (SPR). Figure 2 illustrates an exemplary successful PSCell report (SPR) 200, according to existing techniques. An example specification 200 is given in Figure 2. In the existing systems, SPR contents may be defined in Table 4 provided below:

[0129] Table 4

[0130]

[0131] Further, Radio Link Failure (RLF) procedures are introduced to allow the UE to regain a radio link in case the radio link fails. After having been triggered, the UE performs RRC re-establishment or recovery using the LTM candidate cells or conditional handover candidate cells, which means that the UE performs cell selection to potentially find a new cell (the same cell is a possible outcome) and connects to the cell. If the reestablishment or recovery is not feasible, the UE moves to an RRC_IDLE state. The UE logs information related to the RLF in the RLF report.

[0132] The RLF is declared in a number of cases. Some examples are:

[0133] ● The UE is out of synchronization,

[0134] ○ The UE measures the cell strength through radio link monitoring. If the cell strength is below a certain threshold for a configurable number of times (N310), the UE triggers a timer (T310) for the UE to recover. If the UE does not recover, the UE declares the RLF.

[0135] ○ The recovery condition is that the UE receives an in-sync indication a configurable amount of times (N311) during the T310 timer duration.

[0136] ● RLC Protocol Data Units (PDUs) are re-transmitted a number of times

[0137] ○ The network configures a number of times (maxRetxThreshold) that an RLC PDU may be attempted to be re-transmitted.

[0138] ● Random access problems

[0139] ○ The random access problems occur when the UE is in connected mode and the UE is trying to re-synchronize, for instance, after losing uplink synchronization.

[0140] ● Backhaul (BH) RLF (Integrated Access and Backhaul (IAB) related)

[0141] ○ Failure of backhaul links

[0142] ● Uplink Listen Before Talk (LBT) failure

[0143] ○ When the UE fails the LBT on an unlicensed band.

[0144] Although a handover failure does cause the UE to declare the RLF, a handover failure is still treated as the RLF in some cases, thus, handover failures are considered a part of an RLF report.

[0145] The RLF report includes the following information:

[0146] - Measurements of serving and neighbouring cells;

[0147] - The C-RNTI of the UE used;

[0148] - The previous Cell ID;

[0149] - The failed Cell ID;

[0150] - The Reconnect cell ID;

[0151] - Time until reconnection;

[0152] - Reestablishment cell ID;

[0153] - Time of connection failure;

[0154] - Time since the failure;

[0155] - Connection failure type - RLF or a Handover Failure;

[0156] - RLF cause - T310 expiry (receiving lower layer out-of-sync indications), random access problem, RLC maximum number of retransmissions, beam failure recovery, LBT, IAB backhaul radio link failure, T312 expiry;

[0157] - Location information of the UE;

[0158] - No suitable cell found;

[0159] - Random access information;

[0160] - Handover type - Conditional Handover (CHO) or Dual Active Protocol Stack (DAPS);

[0161] - Time since CHO reconfiguration or DAPS failure;

[0162] - E-UTRA RLF report including E-UTRA measurement result and cell ID of E-UTRA cell;

[0163] - CHO information such as CHO cell ID and CHO candidate cell list;

[0164] - MCG failure causes - T316 expiry or SCG deactivation;

[0165] - SCG failure causes - same as RLF cause;

[0166] - Time elapsed since SCG failure;

[0167] - Voice fallback handover;

[0168] - Received Signal Strength Indicator (RSSI) serving and neighbour cell measurement results; and

[0169] - Bandwidth Part (BWP) information.

[0170] When the RLF report is for the SCG, the UE includes the information for Self-Organizing Networks or Minimization of Drive Tests (SON / MDT) in SCGFailureInformation.

[0171] If available, the UE logs the L1 measurements for the serving cell, the target cell, and other LTM candidate cells in the RLF report, upon RLF or mobility failure. The UE also may log the L1 measurements in the SHR, the SPR, the SCGFailureInformation, etc. Version 18.1.0 of TSs 38.331, 38.321, 38.306, 37.340, 38.300 are considered as background for the present disclosure.

[0172] Further, in conditional LTM (C-LTM), the UE is configured with a condition and upon the fulfilment of the condition, the UE executes the LTM cell switch. Conditions for the C-LTM is based on a measured L1 RSRP, an L1 Reference Signal Received Quality (RSRQ), or an L1 Signal to Interphase plus Noise Ratio (SINR) of serving cell and neighbour cell. Further, the L1 RSRP, the L1 RSRQ, the L1 SINR are filtered before using the L1 RSRP, the L1 RSRQ, the L1 SINR for the C-LTM. The conditions may be also based on an L3 RSRP, an L3 RSRQ, an L3 SINR, etc.

[0173] For e.g., the UE is configured to perform the conditional LTM when the serving cell's measured RSRP or RSRQ is below a predefined threshold and that of the neighbour cell is above the predefined threshold.

[0174] In another case, the UE is configured to perform the conditional LTM when the neighbour cell's measured RSRP or RSRQ is better than an offset of that of the serving cell.

[0175] There is no SON / MDT optimisation available for the conditional LTM.

[0176] In another case, the UE is configured with a condition and upon the fulfilment of the condition, the UE initiates random access for receiving the early Timing Advance (TA is like random access performed for PDCCH ordered RACH).

[0177] The UE receives the timing advance in a random access response or in a MAC control element. The reception of timing advance by performing random access upon fulfilment of a condition is referred to as conditional early RACH synchronization. Conditions can be based on the measured L1 RSRP or the L1 RSRQ or the L1 SINR of the serving cell and the neighbour cell. The conditions can also be based on measured L3 RSRP, L3 RSRQ, or L3 SINR of the serving cell and the neighbour cell. For e.g., the UE is configured to perform conditional early RACH synchronisation when the serving cell's measured RSRP or RSRQ is below a predefined threshold and that of the neighbour cell is above the predefined threshold. In another case, the UE is configured to perform the conditional LTM when the neighbour cell's measured RSRP or RSRQ is better than an offset from that of the serving cell.

[0178] Therefore, there is a need for a solution that overcomes the above deficiencies and addresses issues such as the reporting of L1 measurements logged by the UE for the serving cell, target cell, and other LTM candidate cells during a RLF or mobility failure, and also considers the conditional LTM for optimisation.

[0179] This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention nor is it intended for determining the scope of the invention.

[0180] According to an embodiment of the present disclosure, a method performed by a User Equipment (UE) for network optimization is disclosed. The method includes performing Layer 1 (L1) measurements associated with one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells. Further, the method includes detecting at least one of a mobility event or a failure event. Furthermore, the method includes transmitting, to a network entity, a report based on the detection. The report comprises one or more of the L1 measurements, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements.

[0181] According to another embodiment of the present disclosure, a method performed by a network entity for network optimization is disclosed. The method includes receiving, from a User Equipment (UE), a report. The report comprises one or more of Layer 1 (L1) measurements corresponding to each of one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells corresponding to the UE, and the PCI and a channel frequency number corresponding to the L1 measurements. Further, the method includes mapping the L1 measurements to one of the one or more LTM candidate cells based on the report for network optimization.

[0182] According to yet another embodiment of the present disclosure, a User Equipment (UE) for network optimization is disclosed. The UE includes a memory and a processor operatively coupled to the memory. The processor is configured to perform Layer 1 (L1) measurements associated with one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells. The processor is also configured to detect at least one of a mobility event or a failure event. The processor is further configured to transmit, to a network entity, a report based on the detection. The report comprises one or more of the L1 measurements, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements.

[0183] According to an embodiment of the present disclosure, a network entity for network optimization is disclosed. The network entity includes a memory and a processor operatively coupled to the memory. The processor is configured to receive, from a User Equipment (UE), a report. The report comprises one or more of Layer 1 (L1) measurements corresponding to each of one or more of a source cell, a target cell, and one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells corresponding to the UE, and a Physical Cell Identity (PCI) and a channel frequency number corresponding to the L1 measurements. The processor is also configured to map the L1 measurements to one of the one or more LTM candidate cells based on the report for network optimization.

[0184] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

[0185] Figure 3 illustrates a block diagram depicting an environment 300 for network optimization, in accordance with an embodiment of the present disclosure. In an embodiment, the environment 300 may include a User Equipment (UE) 302, a network entity 304, and a network 306. Examples of the UE 302 may include, but are not limited to, a smartphone, a computing device, a tablet, a laptop, an Internet of Things (IoT) device, a smartwatch, an Augmented Reality (AR) headset, a Virtual Reality (VR) headset, or Extended Reality (XR) headsets, an embedded system with display and input capabilities, and the like. In an embodiment, examples of the network entity 304 may include, but are not limited to, a Next Generation NodeB (gNB) - Distributed Unit (gNB-DU), a gNB-Central Unit (gNB-CU),anAccess and Mobility Management Function (AMF), and the like.

[0186] In an embodiment, the UE 302 may be configured to perform Layer 1 (L1) measurements associated with one or more of a source cell, a target cell, and one or more LTM candidate cells. The L1 measurements may include Reference Signal Received Power (RSRP) measurements corresponding to each of the one or more of the source cell, the target cell, and the one or more LTM candidate cells. The UE 302 may include a RSRP range as the RSRP measurements.

[0187] In an embodiment, the UE may be configured to perform the L1 measurements in response to one or more configuration instructions. The one or more configuration instructions may be prestored at the UE. Alternatively, the one one or more configuration instructions may be received from the network entity 304 for performing one or more mobility procedures. The one or more configuration instructions may include one or more information elements and one or more signalling parameters. Further, examples of the one or more mobility procedures may include, but are not limited to, a Layer1 / Layer2 Triggered Mobility (LTM), a Conditional-LTM (C-LTM), and the like.

[0188] The source cell may refer to a serving cell of the UE 302 from which the one or more mobility procedures are initiated. The source cell may be the cell currently providing radio resources to the UE 302 for data and control communication. Further, the target cell may be a cell identified as a preferred replacement for the source cell during the mobility event. The target cell may be selected by the network entity 304 or the UE 302 and may be intended to become a new serving cell upon successful completion of a cell switch or handover.

[0189] The LTM cell switch may refer to a change of the serving cell initiated and executed at the lower layers L1 or L2. The LTM cell switch may be based on the L1 measurements. The LTM cell switch may be aimed at reducing latency. Further, the SHO may be a mobility procedure in which the UE 302 transitions from the source cell to the target cell. The handover may be considered successful when the UE 302 completes reconfiguration to the target cell and resumes communication without service interruption.

[0190] The successful PScell addition may refer to a successful addition of a Primary Secondary Cell Group Cell in a Dual Connectivity (DC) (e.g., when connected to a master gNB and a secondary gNB). A PSCell may be the primary cell of the SCG, and a successful addition means the UE 302 has established a working connection to the SCG via the added PScell.

[0191] Further, the successful PScell change may occur when the current PSCell in the SCG is replaced by another secondary cell, typically due to changes in signal quality or mobility requirements. The procedure may involve reconfiguring the SCG to reflect a new PSCell and is deemed successful if the communication continues without failure.

[0192] The one or more LTM candidate cells may refer to a set of one or more cells pre-configured by the network entity 304 and monitored by the UE 302. The one or more LTM candidate cells may be evaluated for the network optimization based on the L1 measurements.

[0193] In an embodiment, the UE 302 may be configured to detect the mobility event or a failure event.

[0194] In an embodiment, the RLF may refer to a condition where the UE 302 is no longer able to maintain a reliable radio link with the serving cell, typically due to degradation in signal quality or loss of synchronization. The UE 302 detects the RLF based on a predefined criteria and initiates recovery procedures such as cell re-establishment or move to an RRC_IDLE state.

[0195] The HO failure may occur when a handover procedure from the source cell to the target cell is not completed successfully. The HO failure may happen due to issues such as the UE 302 failing to access the target cell, a mismatch in reconfiguration parameters, or failure to receive necessary RRC messages. The UE 302 may typically trigger an RRC re-establishment or fallback procedure in such cases.

[0196] The UE 302 may inform the network entity 304 that the LTM cell switch failure is due to an execution of the conditional LTM. Further, the LTM cell switch failure may be due to incorrect beam selection, synchronization issues, or inability to decode necessary downlink information from the one or more LTM candidate cells. The SCG failure may refer to a disruption in a connection between the UE 302 and a SCG in the DC. The SCG failure may result from the degradation or loss of the PScell, synchronization loss, or radio link issues in the SCG.

[0197] In an embodiment, the UE 302 may be configured to transmit a report based on the detection of the mobility event or the failure event to the network entity 304. The report may include the L1 measurements, a Physical Cell Identity (PCI) and a channel frequency number (such as New Radio - Absolute Radio-Frequency Channel Number (NR-ARFCN)) corresponding to the L1 measurements. The PCI and the channel frequency number may be associated with the one or more LTM candidate cells. The report may also include a Synchronization Signal Block (SSB) index corresponding to an SSB used to obtain the RSRP measurements, and an absolute RSRP range corresponding to one or more SSBs. The SSB index may include a Synchronization Signal and / or a Physical Broadcast Channel (PBCH).

[0198] Further, the report may correspond to a Self-Organizing Networks or Minimization of Drive Tests (SON or MDT) report. The SON or MDT may include at least one of an RLF report, a Successful Handover Report (SHR), a Successful PSCell Addition or Change Report (SPR), and a SCGFailureInformation.

[0199] In an embodiment, the RLF report may be generated by the UE 302 after the RLF occurs. The RLF report may include identity of the failed cell, cause and time of failure, neighboring cell measurements. The SHR may indicate that the handover procedure is completed successfully. The SHR may include source and target cell identities and timing and quality measurements. The SPR may indicate a successful addition or change of the PSCell in the DC. Further, the SPR may include PSCell identity and time of the mobility event. The SCGFailureInformation may include a detailed report generated by the UE 302 when the SCG failure occurs in a DC scenario.

[0200] Furthermore, the UE 302 may be configured to log the report and transmit the logged report to the network entity 304. The logged report may be transmitted to the network entity in a UEInformationResponse message. The UEInformationResponse message may be an RRC uplink message sent by the UE 302 to the network entity 304.

[0201] In an embodiment, when the one or more mobility procedures may correspond to the C-LTM, the report may include a type of last executed mobility procedure. The report may also include information associated with one or more LTM candidate cells configured for the C-LTM. Further, the report may include an indication of whether a neighbour cell associated with the UE 302 is an LTM candidate cell configured for the C-LTM. Furthermore, the report may include the information associated with one or more LTM candidate cells configured for the C-LTM for a Master Cell Group (MCG). In addition, the report may include an indication of whether the neighbour cell is the LTM candidate cell configured for the C-LTM for the MCG.

[0202] The report may include the information associated with one or more conditional events fulfilled for the C-LTM, and a time elapsed between fulfillment of the one or more conditional events. Further, the report may include the information associated with one or more conditional events fulfilled for the C-LTM for the MCG. Furthermore, the report may include a time elapsed between fulfillment of the one or more conditional events. In addition, the report may include the information associated with one or more conditional events fulfilled for the C-LTM for the SCG. Further, the report may include a time elapsed between fulfillment of the one or more conditional events. The UE 302 and the network entity 304 are described in greater detail in conjunction with Figure 10 and Figure 11 in the forthcoming paragraphs.

[0203] In an embodiment, the UE 302 may be configured to set pSCellId to a source PSCell (in case of PSCell change) or PSCell (in case of no PSCell change). If the UE 302 supports the RLF report, L1 measurement quantities based onSynchronization Signal or Physical Broadcast Channel (SS or PBCH) blocks may be available. Further, the UE 302 may be configured to set resultsSSB-Indexes in measResultL1LastServCell to include available measurement quantities of the source PCell (in case the HO failure) or PCell (in case of the RLF), ordered such that the highest SS / PBCH block L1-RSRP is listed first, based on the available SS / PBCH block-based L1 measurements collected up to the moment the UE detected failure.

[0204] Further, if the UE 302 supports the RLF report for the LTM, for each neighbour LTM candidate cells. If the SS / PBCH block-based L1-RSRP measurement quantities are available, measResultL1NeighCells field may be populated with all the available SS / PBCH block-based L1-RSRP measurement results corresponding to the best measured neighboring cells. The UE 302 may exclude the source PCell in the case of the HO failure or the serving PCell in the case of the RLF. The measurement results are to be ordered such that the cell with the highest SS / PBCH block-based L1-RSRP―among all measured SS / PBCH blocks for that cell―is listed first, followed by others in descending order of the highest measured SS / PBCH block-based L1-RSRP.

[0205] In an embodiment, if the UE 302 supports the SHR for the LTM, the resultsSSB-Indexes field in sourceCellMeasL1 may be set to include all available SS / PBCH block-based L1-RSRP measurement quantities of the source PCell that have been collected by the UE 302 up to the moment the UE 302 transmits the RRCReconfigurationComplete message. The measurements may represent the per-SSB signal strength of the source PCell, allowing the network to analyze beam-level quality at the time of reconfiguration completion.

[0206] In an embodiment, if the UE 302 supports the SHR for the LTM, the resultsSSB-Indexes field in targetCellMeasL1 may be set to include all available SS / PBCH block-based L1-RSRP measurement quantities of the target PCell have been collected by the UE 302 up to the moment the UE 302 transmits the RRCReconfigurationComplete message.

[0207] In an embodiment, if the UE 302 supports the SHR for the LTM, for each neighboring MCG LTM candidate cell included in the current UE configuration, if SS / PBCH block-based L1-RSRP measurement quantities are available, the UE 302 sets the neighCellsMeasL1ListNR field accordingly. The neighCellsMeasL1ListNR field may include all available SS / PBCH block-based L1-RSRP measurement results of the best measured cells, excluding the source PCell and the target PCell. The measurement results may be ordered such that the cell with the highest SS / PBCH block-based L1-RSRP―among all SSBs for that cell―is listed first. The measurement results may be based on data collected up to the time the UE 302 sends the RRCReconfigurationComplete message to the network entity 304.

[0208] Figure 4 illustrates a flowchart depicting a method 400 of reporting Lower layers (l1 / l2 layers) Triggered Mobility (LTM) measurements for Self-Organizing Networks (SON) / Minimization of Drive Tests (MDT), according to an embodiment of the present disclosure. In an embodiment, the method 400 may be implemented by the UE 302.

[0209] At step 402, the method 400 may include receiving the LTM configuration. At step 404, the method 400 may include performing the L1 measurements for the LTM on the source and LTM candidate cells. At step 406, the method 400 may include reporting LxM L1 measurements for the LTM, where L is the number of cells reported and M is the number of beams reported. The reporting may include the SSB-RI and differential RSRP for LxM-1 entries. At step 408, the method 400 may include detecting, for example, RLF or successful LTM cell switch or SCG RLF or successful SCG LTM cell switch. At step 410, the method 400 may include incorporating in SON / MDT reports all available LTM measurements for all the cells (source cell or target cell or LTM candidate cells) and SSBs. The SON / MDT report may also include CGI information or PCI / frequency information of the LTM candidate cells, and the SSB index along with RSRP-Range

[0210] Figure 5 illustrates a flowchart depicting a method 500 of logging conditional LTM information for the SON / MDT, according to an embodiment of the present disclosure. In an embodiment, the method 500 may be implemented by the UE 302.

[0211] At step 502, the method 500 may include receiving conditional LTM configuration. At step 504, the method 500 may include detecting, for example, the RLF or the successful LTM cell switch or the SCG RLF or the successful SCG LTM cell switch. At step 506, the method 500 may include incorporating in the SON / MDT reports information that last handover is conditional LTM, list of the LTM candidate cells for the conditional LTM, information whether the cell where measurements are logged is an LTM candidate cell for the conditional LTM, list of fulfilled events for the conditional LTM, time elapsed between the configuration of the conditional LTM and the RLF or successful mobility or failed mobility, time elapsed between the RLF or the successful mobility or the failed mobility and the fulfilment of events for the conditional LTM, first fulfilled event for conditional LTM, time elapsed between events for the conditional LTM, etc.

[0212] Figure 6 illustrates a flowchart depicting a method 600 of logging conditional early synchronisation information for SON / MDT, according to an embodiment of the present disclosure. In an embodiment, the method 600 may be implemented by the UE 302.

[0213] At step 602, the method 600 may include receiving configuration for the conditional early synchronisation. At step 604, the method 600 may include detecting, for example, the RLF or the successful LTM cell switch or the SCG RLF or the successful SCG LTM cell switch. At step 606, the method 600 may include incorporating in the SON / MDT reports a list of the LTM candidate cells for the conditional early synchronisation, information whether the cell where measurements are logged is configured as candidate for the conditional early synchronisation, a list of fulfilled events for the conditional early synchronisation, a time elapsed between the configuration of the conditional early synchronisation and the RLF or the successful mobility or the failed mobility, a time elapsed between the RLF or the successful mobility or the failed mobility and the fulfilment of events for early synchronisation, a first fulfilled event for the conditional early synchronisation, a time elapsed between events for the conditional early synchronisation, etc.

[0214] Figure 7 illustrates an exemplary reporting 700 of LTM measurements in SON / MDT reports, according to an embodiment of the present disclosure.

[0215] In an embodiment, the UE 302 reporting the L1 measurements for LTM, reports the information to map the L1 measurements to the corresponding LTM candidate cells in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. In an embodiment, UE includes the LTM candidate identifier (such as ltm-CandidateId-r18 in NR) in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. This may be included along with the L1 measurements for LTM and also may be used for mapping the reported L1 measurements to the corresponding candidate cell.

[0216] In an embodiment, the UE 302 includes the CGI information (such as CGI-Info-Logging-r16 in NR) of the LTM candidate cells in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. This may be included along with the L1 measurements for LTM and also may be used for mapping the reported L1 measurements to the corresponding candidate cell. Including CGI information of the LTM candidate cells in the SON / MDT reports allow the serving cell to identify the neighbour cell even when the same PCI and frequency are allocated to multiple neighbours. It also allows the processing / retrieval of the neighbour cell information at a later point of time, where the candidate identifier could be reallocated to different candidate cells.

[0217] In an embodiment, the UE 302 includes the NR Cell Global Identifier (NCGI) of the LTM candidate cells in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. This may be included along with the L1 measurements for LTM and also may be used for mapping the reported L1 measurements to the corresponding candidate cell.

[0218] In an embodiment, the UE 302 includes CGI information (such as CGI-Info-Logging-r16 in NR) of the LTM candidate cells if the LTM candidate cell is an inter-gNB (inter-CU) candidate cell. In an embodiment, UE does not include CGI-Info-Logging-r16 of the LTM candidate cells if the LTM candidate cell is not an inter-gNB (inter-CU) candidate cell (i.e. the cell is an intra-CU LTM candidate cell).

[0219] In an embodiment, the UE 302 includes the physical cell identity and carrier frequency number of the LTM candidate cell in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. This may be included along with the L1 measurements for LTM and also may be used for mapping the reported L1 measurements to the corresponding candidate cell. This may be used in implementations where the same PCI and frequency are allocated to multiple neighbours or where the network can distinctly identify the neighbours with the same PCI and frequency based on other factors such as the deployment map.

[0220] In an embodiment, if the LTM candidate cell is an intra-CU LTM candidate cell, the UE 302 includes the physical cell identity and carrier frequency number of the LTM candidate cell in the above SON / MDT reports and SCGFailureInformation and doesn't include the CGI information.

[0221] In an embodiment, if the LTM candidate cell is an inter-CU LTM candidate cell, the UE 302 includes the CGI information (such as CGI-Info-Logging-r16 in NR) in the above SON / MDT reports and SCGFailureInformation when the CGI information (such as CGI-Info-Logging-r16 in NR) is available. If the CGI information (such as CGI-Info-Logging-r16 in NR) is not available, UE includes the physical cell identity and carrier frequency of the LTM candidate cell in the above SON / MDT reports and SCGFailureInformation.

[0222] In an embodiment, the UE 302 includes the sub carrier spacing (SCS) of the LTM candidate in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. In an embodiment, the SCS may be the SCS received in the LTM-SSB-Config-r18 of the LTM candidate. This may be included along with the L1 measurements and also may be used for mapping the reported L1 measurements to the corresponding candidate cell.

[0223] In an embodiment, the UE 302 includes the ssb-index of the SSB used for measuring the L1 RSRP while reporting the L1 measurements for LTM in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. While the SSB-RI is reported in the L1 reporting, UE includes the actual ssb-index itself in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. The L1 measurements for LTM may correspond to the source cells, target cells or other LTM candidate cells.

[0224] In an embodiment, the UE 302 includes the rsrp-range as the L1 RSRP measurements while reporting the L1 measurements for LTM in SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. In an embodiment, the L1 RSRP measurements are performed on SSB or CSI-RS. While the UE may include differential RSRP in the L1 reports for the network for LTM cell switch for LxM-1 values as explained in the background, the UE includes only absolute RSRP range value (for e.g. as in Table 10.1.6.1-1 of TS 38.133) in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. Reporting the absolute RSRP range is more costly in terms of the signaling, but this will allow easier processing of RRC signaling. For e.g. this will allow easier implementation of ASN.1 encoding before reporting on the air interface. Since the SON / MDT reports are retrieved using RRC signaling, it may be useful to consider simpler implementation and report all the values using absolute RSRP range. The L1 measurements for LTM may correspond to source cells, target cells or other LTM candidate cells.

[0225] In an embodiment, the UE 302 includes the L1 RSRP measurements of the LTM candidate cells for which the measurements are last reported to the DU at the beginning of the list sent for reporting the L1 measurements for LTM in the SON / MDT reports. i.e. if the UE has last sent LTM measurements to DU (i.e. in CSI reports.) For n LTM candidate cells and the UE is including the LTM measurements for n+m LTM candidate cells in the SON / MDT reports, UE first includes the LTM measurements for the n LTM candidate cells for which it has last send LTM measurements to DU and then includes the LTM measurements for remaining m LTM candidate cells.

[0226] In an embodiment, the UE 302 includes the L1 RSRP measurements of the SSBs or CSI-RSs for which the measurements are last reported to the DU at the beginning of the list sent for reporting the L1 measurements for LTM in the SON / MDT reports. i.e. if the UE has last sent LTM measurements to DU (i.e. in CSI reports.)for p SSBs in a LTM candidate cell and the UE is including the LTM measurements for p+q SSBs for that LTM candidate cell in the SON / MDT reports, UE first includes the LTM measurements for the p SSBs for which it has last send LTM measurements to DU and then includes the LTM measurements for remaining q SSBs, as depicted in Figure 7.

[0227] In an embodiment, the UE 302 includes the CSI-RS index of the CSI-RS used for measuring the L1 RSRP while reporting the L1 measurements for LTM in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. The L1 measurements for LTM may correspond to source cells, target cells or other LTM candidate cells.

[0228] In an embodiment, the UE 302 includes the time elapsed between the configuration of the LTM candidate cell and an event (such as the radio link failure or successful LTM cell switch switch or SCG RLF or successful LTM cell switch in SCG) in the SON / MDT reports (such as RLF report, SHR, SPR and in the SCGFailureInformation). In an embodiment, the UE includes an identifier of the cell (Identifier can be PCI, NR-CGI, PCI+frequency information, candidate identifier etc.) which was the primary cell when the UE received the configuration of the LTM candidate cell in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. The event mentioned above can be RLF for RLF report, successful LTM cell switch of MCG for SHR, SCG RLF for SCGFailureInformation and successful LTM cell switch of SCG for SPR. In an embodiment, this cell can be the cell where the LTM configuration is added. In an embodiment, this cell can be the cell where the LTM configuration is last modified.

[0229] In an embodiment, the UE 302 includes the time elapsed between the configuration of LTM candidate cell and an event (such as the radio link failure or successful LTM cell switch switch or SCG RLF or successful LTM cell switch in SCG) in the SON / MDT reports (such as RLF report, SHR, SPR and in the SCGFailureInformation), if there was no LTM cell switch after the reception of the LTM configuration for the candidate cell. In the case of subsequent LTM, the time elapsed between the configuration of the LTM candidate cell and the event is not logged. The event mentioned above can be RLF for RLF report, successful LTM cell switch of MCG for SHR, SCG RLF for SCGFailureInformation and successful LTM cell switch of SCG for SPR.

[0230] If the LTM configuration for the candidate cell is received in the source cell and there is no LTM cell switch after the reception of the LTM configuration for the candidate cell, the UE 302 includes the time elapsed between the configuration of LTM candidate cell and an event such as the radio link failure or successful LTM cell switch or SCG RLF or successful LTM cell switch in SCG in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. The event mentioned above can be RLF for RLF report, successful LTM cell switch of MCG for SHR, SCG RLF for SCGFailureInformation and successful LTM cell switch of MCG for SPR.

[0231] In an embodiment, the UE 302 includes the time elapsed between the configuration of LTM candidate cell and an event such as the radio link failure or successful LTM cell switch or SCG RLF or successful LTM cell switch in SCG in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation, if the LTM configuration for the candidate cell is received in the source cell and there was no LTM cell switch or L3 mobility after the reception of the LTM configuration for the candidate cell. The event mentioned above can be RLF for RLF report, successful LTM cell switch of MCG for SHR, SCG RLF for SCGFailureInformation and successful LTM cell switch of SCG for SPR.

[0232] In an embodiment, if the LTM cell switch due to conditional LTM fails, the UE 302 informs the network that the LTM cell switch failure is due to the execution of conditional LTM.

[0233] In an embodiment, if the LTM cell switch due to conditional LTM fails, the UE 302 may inform the network that the last handover executed is the execution of conditional LTM.

[0234] In an embodiment, in NR, lastHO-Type in RLF-Report may be used to indicate the conditional LTM cell switch as the last executed mobility procedure.

[0235] In an embodiment, the UE 302 informs the network of the LTM candidate cells which are configured for conditional LTM in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. In an embodiment, the UE indicates if a neighbour cell for which the LTM measurements (L1 measurements for LTM) are included in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation is an LTM candidate cell configured for conditional LTM.

[0236] In an embodiment, the UE 302 informs the network of the LTM candidate cells which are configured for conditional LTM for MCG in RLF report or SHR. In an embodiment, the UE 302 indicates if a neighbour cell for which the LTM measurements (L1 measurements for LTM) are included in the SON / MDT reports such as RLF report or SHR is a LTM candidate cell configured for conditional LTM configured for MCG.

[0237] In an embodiment, the UE 302 informs the network of the LTM candidate cells which are configured for conditional LTM for SCG in the SPR and in the SCGFailureInformation. In an embodiment, the UE indicates if a neighbour cell for which the LTM measurements (L1 measurements for LTM) are included in the SON / MDT reports such as SPR and in the SCGFailureInformation is an LTM candidate cell configured for conditional LTM configured for SCG.

[0238] In an embodiment, the UE 302 informs the network of the LTM or CHO / CPAC candidate cells which are configured for conditional early synchronisation in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. In an embodiment, the UE indicates if a neighbour cell for which the LTM measurements (L1 measurements for LTM) or L3 measurements are included in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation is an LTM candidate cell configured for conditional early synchronization or a CHO / CPAC candidate cell.

[0239] In an embodiment, the UE 302 informs the network that the (LTM or CHO / CPAC) candidate cells are configured for conditional early synchronisation for MCG in RLF report or SHR. In an embodiment, the UE indicates if a neighbour cell for which the LTM measurements (L1 measurements for LTM) or L3 measurements are included in the SON / MDT reports such as RLF report or SHR is a LTM candidate cell configured for conditional early synchronisation configured for MCG or a CHO candidate cell.

[0240] In an embodiment, the UE 302 informs the network of the LTM or CHO / CPAC candidate cells which are configured for conditional early synchronisation for SCG in the SPR and in the SCGFailureInformation. In an embodiment, the UE indicates if a neighbour cell for which the LTM measurements (L1 measurements for LTM) or L3 measurements are included in the SON / MDT reports such as SPR and in the SCGFailureInformation is a LTM candidate cell configured for conditional LTM configured for SCG or a CPAC candidate cell.

[0241] In an embodiment, the UE 302 informs the network of the conditional event which was first fulfilled, and the time elapsed between the fulfilment of conditional events which are fulfilled for conditional LTM in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation.

[0242] In an embodiment, the UE 302 informs the conditional event that was first fulfilled, and the time elapsed between the fulfilment of conditional events which are fulfilled for conditional LTM for MCG in RLF report or SHR.

[0243] In an embodiment, the UE 302 informs the conditional event that was first fulfilled, and the time elapsed between the fulfilment of conditional events which are fulfilled for conditional LTM for SCG in the SPR and in the SCGFailureInformation.

[0244] In an embodiment, the UE 302 informs the network of the conditional event which was first fulfilled, and the time elapsed between the fulfilment of conditional events which are fulfilled for conditional early synchronisation in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation.

[0245] In an embodiment, the UE 302 informs the conditional event which was first fulfilled, and the time elapsed between the fulfilment of conditional events which are fulfilled for conditional early synchronisation for MCG in RLF report or SHR.

[0246] In an embodiment, the UE 302 informs the conditional event which was first fulfilled, and the time elapsed between the fulfilment of events which are fulfilled for conditional early synchronisation for SCG in the SPR and the SCGFailureInformation.

[0247] In an embodiment, the UE 302 includes the time elapsed between the fulfillment of conditional events for LTM candidate cell and an event such as the radio link failure or successful LTM cell switch or SCG RLF or successful LTM cell switch in SCG, in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. Event can be RLF for RLF report, successful LTM cell switch of MCG for SHR, SCG RLF for SCGFailureInformation and successful LTM cell switch of SCG for SPR.

[0248] In an embodiment, the UE 302 includes the time elapsed between the fulfillment of conditional events associated with conditional early synchronisation and an event such as the radio link failure or successful LTM cell switch or SCG RLF or successful LTM cell switch in SCG in the SON / MDT reports such as RLF report, SHR, SPR and in the SCGFailureInformation. Event can be RLF for RLF report, successful LTM cell switch of MCG for SHR, SCG RLF for SCGFailureInformation and successful LTM cell switch of SCG for SPR.

[0249] Figure 8 illustrates a flowchart depicting a method 800 performed by the UE 302 for the network optimization, in accordance with an embodiment of the present disclosure.

[0250] At step 802, the method 800 may include receiving, from the network entity 304, the one or more configuration instructions for performing the one or more mobility procedures.

[0251] At step 804, the method 800 may include performing the Layer 1 (L1) measurements associated with one or more of the source cell, the target cell, and the one or more Layer1 / Layer2 Triggered Mobility (LTM) candidate cells.

[0252] At step 806, the method 800 may include detecting at least one of the mobility event or the failure event.

[0253] At step 808, the method 800 may include transmitting, to the network entity 304, the report based on the detection. The report may include the one or more of the L1 measurements and the PCI and the channel frequency number corresponding to the L1 measurements. In an embodiment, the report may enable the network entity 304 to map the L1 measurements to one of the one or more other LTM candidate cells for network optimization.

[0254] The UE 302, after receiving the one or more configuration instructions, may perform the required L1 measurements and send the report to the network entity 304. For example, the report may include, for Cell A, Beam 1 = 30 dBm, Beam 2 = 35 and for Cell B: Beam 3 = 45. Reported values may correspond to a measured value according to Table 2.

[0255] In an embodiment, the method 800 may include logging the report. The method 800 may also include sending, to the network entity 304, the logged report in the UEInformationResponse message.

[0256] In an embodiment, when the one or more mobility procedures correspond to the C-LTM, the report may further include the type of last executed mobility procedure. Further, the report may include the information associated with one or more LTM candidate cells configured for the C-LTM. The report may include the indication of whether the neighbour cell associated with the UE 302 is the LTM candidate cell configured for the C-LTM.

[0257] Furthermore, the report may include the information associated with the one or more LTM candidate cells configured for the C-LTM for the MCG. The report may include the indication of whether the neighbour cell is the LTM candidate cell configured for the C-LTM for the MCG. The report may include the information associated with the one or more conditional events fulfilled for the C-LTM, and the time elapsed between fulfillment of the one or more conditional events.

[0258] The report may include the information associated with the one or more conditional events fulfilled for the C-LTM for the MCG, and the time elapsed between fulfillment of the one or more conditional events. The report may include the information associated with the one or more conditional events fulfilled for the C-LTM for the SCG, and the time elapsed between fulfillment of the one or more conditional events.

[0259] Figure 9 illustrates a flowchart depicting a method 900 performed by the network entity 304 for the network optimization, in accordance with an embodiment of the present disclosure.

[0260] At step 902, the method 900 may include transmitting the one or more configuration instructions to the UE 302.

[0261] At step 904, the method 900 may include receiving the report from the UE 302. In an embodiment, the network entity 304 may receive the report in response to transmitting the one or more configuration instructions.

[0262] At step 906, the method 900 may include mapping the L1 measurements to the one of the one or more LTM candidates based on the report for the network optimization.

[0263] Particularly, the network entity 304 may interpret the report, and map the L1 measurements to the one or more LTM candidate cells (based on PCI, channel frequency number, etc.), and makes a decision. The decision may include whether to perform the LTM cell switch, the measurements at which the LTM cell switch may be performed, etc..

[0264] The L1 measurements may include the RSRP measurements corresponding to each of the one or more of the source cell, the target cell, and the one or more other LTM candidate cells.

[0265] In an embodiment, the report may include the SSB index corresponding to the SSB used to obtain the RSRP measurements. The report may include the absolute RSRP range corresponding to the one or more SSBs. Further, the report may correspond to the SON / MDT report. The SON / MDT report may include the RLF report and the SHR.

[0266] For instance, 3rd Generation Partnership Project (3GPP) specification may include, for example, "set the resultsSSB-Indexes in sourceCellMeasL1 to include all available Synchronization Signal / Physical Broadcast Channel (SS / PBCH) block L1-RSRP measurement quantities of the source PCell collected up to the moment the UE 302 sends RRCReconfigurationComplete message.

[0267] Figure 10 illustrates an example block diagram 1000 of the UE 302, in accordance with an embodiment of the present disclosure. The UE 302 may include one or more processors 1002 (also referred to as the "processor" 1002), a memory unit 1004 (also referred to as the "memory" 1004), and a communication unit 1006 (e.g., communicator or communication interface).

[0268] In an embodiment, the processor 1002 may be a single processing unit or a number of units, all of which could include multiple computing units. The processor 1002 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and / or any devices that manipulate signals based on operational instructions. Among other capabilities, the processor 1002 is configured to fetch and execute computer-readable instructions and data stored in the memory unit 1004 to perform operations / functions associated with the the UE 302, as discussed throughout the present disclosure. The processor 1002 may include one or a plurality of processors. At this time, one or a plurality of processors 1002 may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The one or a plurality of processors 1002 may control the processing of the input data in accordance with a predefined operating rule or artificial intelligence (AI) model stored in the non-volatile memory and the volatile memory, i.e., memory unit 1004. The predefined operating rule or artificial intelligence model is provided through training or learning.

[0269] In an embodiment, the memory unit 1004 may include any non-transitory computer-readable medium known in the art including, for example, volatile memory, such as static random access memory (SRAM) and dynamic random access memory (DRAM), and / or non-volatile memory, such as read-only memory (ROM), erasable programmable ROM, flash memories, hard disks, optical disks, and magnetic tapes.

[0270] In an embodiment, the communication unit 1006 may be configured to perform one or more functions for transmitting and receiving signals via a wireless channel.

[0271] Figure 11 illustrates an example block diagram 1100 of network entity 304, in accordance with an embodiment of the present disclosure. The network entity 304 may include one or more processors 1102 (also referred to as the "processor" 1102), a memory unit 1104 (also referred to as the "memory" 1104), and a communication unit 1106 (e.g., communicator or communication interface). The processor 1102, the memory unit 1104, and the communication unit 1106 may be similar to the processor 1002, the memory unit 1004, and the communication unit 1006 of Figure 10. Therefore, the description of the processor 1102, the memory unit 1104, and the communication unit 1106 has been omitted in respect of Figure 11 for the sake of brevity.

[0272] The present disclosure provides various advantages. Particularly, mobility decisions (e.g., serving cell change) are performed using L1 / L2 signaling, thereby avoiding time-consuming RRC-level handover procedures. The present invention enables the optimisation of the LTM and the C-LTM. The present invention allows the UE to report the L1 measurements more accurately for optimisation by using an absolute RSRP range rather than the differential RSRP used during making mobility decisions. Further, the present invention allows the UE to report the PCI and carrier frequency number of the candidate cells unlike the candidate cell identifier reported for LTM execution, thereby allowing the retrieval of the report at a later point of time by the network. Similarly, the present invention allows more precise reporting of SSB information. Further, the present invention reduces air-interface and processing load at the UE and the network entity. The present invention enables the network entity to map measurements to exact cells, thereby improving mobility robustness and avoiding incorrect switch decisions.

[0273] Additionally, the present invention supports reporting of L1 measurements in the context of RLF, HO failure, or SCG failure, allowing the network to correlate failures with cell conditions.

[0274] The present invention also enables the SON / MDT for C-LTM where the UE autonomously switches the cells based on its measurements utilising the configuration from the network. Moreover, the present invention allows the network entity to identify the L1 measurements used for C-LTM, thereby providing an option for improving decision quality.

[0275] While specific language has been used to describe the present subject matter, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein.

[0276] It is understood that terms including "unit" or "module" at the end may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

[0277] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0278] Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

[0279] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

[0280] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of at least one embodiment, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

1.A method performed by a user equipment (UE) in a communication system, the method comprising:receiving, from a base station, a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information;based on the LTM configuration information, performing an L1 measurement; andin case that a radio link failure (RLF) for the LTM is detected, transmitting, to a base station, a RLF report,wherein the RLF report includes first L1 measurement result information associated with the LTM.2.The method of claim 1,wherein the L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.3.The method of claim 1,in case that a successful handover for the LTM is detected, transmitting, to the base station, a successful handover report,wherein the successful handover report includes second L1 measurement result information.4.The method of claim 3,wherein the second L1 measurement result information is associated with at least one of a source cell L1 measurement result, target cell L1 measurement result, or a neighbor cell L1 measurement result, andwherein the second L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.5.A method performed by a base station in a communication system, the method comprising:transmitting, to a user equipment (UE), a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information, wherein an L1 measurement is performed based on the LTM configuration information; andin case that a radio link failure (RLF) for the LTM is detected, receiving, from the UE, a RLF report,wherein the RLF report includes first L1 measurement result information associated with the LTM.6.The method of claim 5,wherein the L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.7.The method of claim 5,in case that a successful handover for the LTM is detected, receiving, from the UE, a successful handover report,wherein the successful handover report includes second L1 measurement result information.8.The method of claim 7,wherein the second L1 measurement result information is associated with at least one of a source cell L1 measurement result, target cell L1 measurement result, or a neighbor cell L1 measurement result, andwherein the second L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.9.A user equipment (UE) in a communication system, the UE comprising:a transceiver, anda controlled coupled with the transceiver, and configured to:receive, from a base station, a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information,based on the LTM configuration information, perform an L1 measurement, andin case that a radio link failure (RLF) for the LTM is detected, transmit, to a base station, a RLF report,wherein the RLF report includes first L1 measurement result information associated with the LTM.10.The UE of claim 9,wherein the L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.11.The UE of claim 9, wherein the controller is further configured to:in case that a successful handover for the LTM is detected, transmit, to the base station, a successful handover report,wherein the successful handover report includes second L1 measurement result information.12.The UE of claim 11,wherein the second L1 measurement result information is associated with at least one of a source cell L1 measurement result, target cell L1 measurement result, or a neighbor cell L1 measurement result, andwherein the second L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.13.A base station in a communication system, the base station comprising:a transceiver, anda controlled coupled with the transceiver, and configured to:transmit, to a user equipment (UE), a radio resource control (RRC) message including Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) configuration information, wherein an L1 measurement is performed based on the LTM configuration information, andin case that a radio link failure (RLF) for the LTM is detected, receive, from the UE, a RLF report,wherein the RLF report includes first L1 measurement result information associated with the LTM.14.The base station of claim 13,wherein the L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.15.The base station of claim 13, wherein the controller is further configured to:in case that a successful handover for the LTM is detected, receive, from the UE, a successful handover report,wherein the successful handover report includes second L1 measurement result information,wherein the second L1 measurement result information is associated with at least one of a source cell L1 measurement result, target cell L1 measurement result, or a neighbor cell L1 measurement result, andwherein the second L1 measurement result information includes at least one synchronization signal block (SSB) index or reference signal received power (RSRP) range associated with the SSB index.

Images