Method and apparatus for performing lower layer triggered mobility in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments herein disclose a method of handling lower layer triggered mobility (LTM) by a UE (100) in a wireless network (1000). The method comprises receiving, from a network entity (200), an RRC reconfiguration comprising an LTM configuration having at least one of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Further, the method comprises, upon successful completion of the RRC reconfiguration, sending the RRC reconfiguration completion to the network entity (200) based on the RRC reconfiguration. Further, the method includes reusing one of: the L3 measurement result, and a portion of the L3 measurement result for LTM measurement, when the UE (100) is measuring the same reference signal for the L3 measurement result and the LTM measurement.

Description

Technical Field

[0001] Embodiments disclosed herein relate to wireless communication networks, and more particularly, to managing lower layer triggered mobility in wireless communication networks. Background Art

[0002] 5G mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be implemented not only in "Sub 6 GHz" frequency bands such as 3.5 GHz, but also in "Above 6 GHz" frequency bands called millimeter waves, including 28 GHz and 39 GHz. In addition, consideration has been given to implementing 6G mobile communication technology (called a super 5G system) in the terahertz (THz) frequency band (for example, the 95 GHz to 3 THz band) to achieve a transmission rate 50 times faster than 5G mobile communication technology and an ultra-low latency one-tenth of that of 5G mobile communication technology.

[0003] At the beginning of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC) and massive machine type communication (mMTC), standardization has been carried out on the following items: beamforming and massive MIMO for mitigating radio wave path loss in millimeter waves and increasing radio wave transmission distance, parameter sets supporting dynamic operation for efficient utilization of millimeter wave resources and time slot formats (for example, operating multiple subcarrier spacings), initial access technology for supporting multi-beam transmission and broadband, definition and operation of BWP (bandwidth part), new channel coding methods such as LDPC (low-density parity check) codes for large-scale data transmission and polar codes for highly reliable transmission of control information, L2 preprocessing, and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, in view of the services that 5G mobile communication technology will support, discussions are underway on improvements and performance enhancements of initial 5G mobile communication technology, and there is already physical layer standardization on the following technologies: such as V2X (Vehicle to Everything) for assisting driving determination of autonomous vehicles based on information about the location and status of the vehicle sent by the vehicle and for enhancing user convenience, NR-U (New Radio Unlicensed) targeting system operation in compliance with various regulatory requirements in unlicensed bands, NR UE energy saving, non-terrestrial network (NTN) as UE satellite direct communication for providing coverage in areas where communication with terrestrial networks is not available, and positioning.

[0005] In addition, standardization of the following technologies is ongoing in the air interface architecture / protocol: for example, the Industrial Internet of Things (IIoT) for supporting new services through interworking and integration with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancements including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access (two-step RACH for NR) for simplifying the random access procedure. Standardization of the following is also ongoing in the system architecture / service: a 5G baseline architecture (e.g., a service-based architecture or service-based interface) for combining network function virtualization (NFV) and software-defined networking (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, an exponentially increasing number of connected devices will be connected to the communication network. Therefore, it is expected that enhanced functionality and performance of 5G mobile communication systems and the integrated operation of connected devices will become necessary. To this end, new research is being planned in conjunction with the following: extended reality (XR) for effectively supporting AR (augmented reality), VR (virtual reality), MR (mixed reality), etc.; improving 5G performance and reducing complexity by utilizing artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communications.

[0007] Furthermore, this evolution of 5G mobile communication systems will serve not only as a foundation for developing: new waveforms for providing coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as full-dimensional MIMO (FD-MIMO), array antennas, and massive antennas, metamaterial-based lenses and antennas for improving the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using OAM (orbital angular momentum), and RIS (reconfigurable smart surfaces); but also as a foundation for developing: full-duplex technology for improving the frequency efficiency of 6G mobile communication technology and improving system networks, AI-based communication technology for achieving system optimization by leveraging 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 a complexity level that exceeds the limits of UE operating capabilities by utilizing ultra-high-performance communication and computing resources.

[0008] In wireless technologies such as Fifth Generation New Radio (5G NR), devices (e.g., UEs) can move between different cells. In RRC_IDLE mode, mobility is performed using a process called cell reselection. Until NR Release 17, mobility in RRC_CONNECTED mode was performed using a process called handover. Network-controlled mobility applies to UEs in RRC_CONNECTED mode. It requires the gNB in NR to trigger explicit RRC signaling. Handover in NR typically involves three steps: handover preparation, handover execution, and handover completion. The gNB can configure the UE to report measurements. Based on the reported measurements or its own understanding of the network topology, the gNB sends an RRC reconfiguration message to handover the UE from the source cell to another cell (called the target cell). The UE accesses the target cell and sends an RRC reconfiguration complete message to the target cell. In another approach (introduced in Third Generation Partnership Project (3GPP) NR Release 16), the gNB can configure execution conditions for the UE to trigger the handover. Once the execution conditions are met, the UE can move to the target cell and send an RRC reconfiguration complete message. 3GPP also introduced a new handover procedure called the Dual Active Protocol Stack (DAPS) handover procedure. In Release 16, the handover procedure maintains the source gNB connection after receiving the RRC message for handover and until the source cell is released after a successful random access to the target gNB. In the case of the DAPS handover procedure, the UE continues to receive downlink user data from the source gNB until the source cell is released and continues to send uplink user data to the source gNB until a successful random access procedure to the target gNB is performed. In all of these methods, the UE performs handover by sending Layer 3 (RRC) messages, which results in considerable signaling overhead and latency issues. Handover, DAPS handover, and conditional handover (CHO) can be referred to as Layer 3 mobility.

[0009] Dual Connection : 3GPP specifies dual connectivity or more technical multi-radio dual connectivity in specifications such as TS 37.340. The details of dual connectivity are summarized below.

[0010] NG-RAN facilitates Multi-Radio Dual Connectivity (MR-DC) operation, in which a UE in RRC_CONNECTED is configured to use radio resources provided by two different schedulers located in separate NG-RAN nodes. These nodes are connected via a non-ideal backhaul, one of which provides access to NR (New Radio) and the other provides access to E-UTRA (Evolved UMTS Terrestrial Radio Access) or NR. One node acts as a master node (MN) while the other functions as a secondary node (SN). The nodes are linked via a network interface, and at least the MN is connected to the core network. The cell group associated with the MN can be called an MCG, and the cell group associated with the SN can be called an SCG. The SN can configure multiple data radio bearers (DRBs) and optional signaling radio bearers (SRBs) for the UE. In NR, the SRBs configured by the SN are called SRB3. Traditionally, wireless technologies have limited the amount and type of data that can be transmitted over SRB3, for example, to ensure that the MN has sufficient control and understanding of the UE's behavior. For example, in NR-DC and NE-DC, in (NG)EN-DC and NR-DC, only measConfig, radioBearerConfig, conditionalReconfiguration, bap-Config, iab-IP-AddressConfigurationList, otherConfig and / or secondaryCellGroup are included in the RRCReconfigurationn received over SRB3, unless the RRCReconfiguration is received in the NR message for resuming the MCG link, such as in DLInformationTransferMRDC. The primary cell of the MCG is called PSCell.

[0011] In the case of dual connectivity, the UE can perform PSCellChange or conditional PSCellChange mainly through layer 3 signaling.

[0012] In the context of dual connectivity, PSCellChange or conditional PSCellChange may also be referred to as Layer 3 mobility. That is, handover, conditional handover, PSCellChange, conditional PSCellChange, etc. refer to L3 mobility. In the context of dual connectivity, PSCellChange or conditional PSCellChange may also be referred to herein as secondary cell group (SCG) Layer 3 mobility, and handover and CHO are referred to as primary cell group (MCG) Layer 3 mobility. Conditional handover and conditional PSCell change may also be referred to as conditional mobility. In addition, the UE may receive RRC configuration for updating some security parameters.

[0013] Traditionally, for conditional mobility, the gNB configures candidate cell configuration after AS security is configured. However, measurement configuration for conditional mobility can be provided before AS security is configured. Similarly, any reference configuration, such as reference signal configuration, can also be provided before AS security is configured. This is done while balancing security requirements with network implementation flexibility. When measurements are configured without AS security, further restrictions can be placed on UE behavior, such as measurement reporting.

[0014] Furthermore, 3GPP specifications such as Technical Specifications (TS) 38.300, TS 38.331, and TS 38.321 V17.2.0 can be considered as relevant background. Furthermore, 3GPP Release 18 is considering lower layer (L1 / L2 layer) triggered mobility (also known as LTM) to address issues such as latency and signaling overhead associated with Layer 3 mobility. According to 3GPP, the goal of LTM is to enable serving cell changes via L1 / L2 signaling to reduce latency, overhead, and disruption time. The network (e.g., gNB, etc.) can configure multiple candidate cells for the UE to allow for rapid application of the candidate cell configuration. The network can also send a Medium Access Control Control-element (MAC CE) or L1 signaling to dynamically switch the UE from the source cell to one of the configured candidate cells. Furthermore, LTM can be triggered based on L1 measurements rather than L3 measurements.

[0015] 3GPP recommends performing LTM without resetting lower layers such as Medium Access Control (MAC) to avoid data loss as much as possible and reduce additional delays in data recovery.

[0016] In addition, the gNB may provide LTMCandidateConfiguration. That is, the gNB may configure LTM candidate cells through one RRCReconfiguration for the candidate target cell, or through one CellGroupConfig for each candidate target cell, or through any similar RRC structure or information element (IE) containing similar fields. For example, a new IE LTM-CandidateConfig may be defined as an ASN.1 sequence that contains CellGroupConfig and some other information elements in RRCReconfiguration. The gNB may further release or modify the candidate configuration. Even after moving to a candidate cell via LTM, the UE may store the LTM configuration of other candidate cells. The gNB may also provide the UE with configurations for performing LTM measurements on different candidate frequencies and candidate cells and reporting based on the performed LTM measurements.

[0017] NR R17 UE may be configured with MeasConfig IE to perform layer 3 measurements. The R17 v17.2.0 NR specification defines MeasConfig as follows.

[0018]

[0019]

[0020] Additional details and definitions of all parameters of MeasConfig are given in 3GPP TS 38.331 V17.2.0.

[0021] The above information is provided as background information only to help readers understand the present disclosure. Applicant has not determined or asserted that any of the above is applicable as prior art to the present application. Summary of the Invention

[0022] Solution to the problem

[0023] The main purpose of the embodiments herein is to disclose methods and wireless networks for handling the coexistence and interaction of LTM (L1 / L2 Triggered Mobility) with various RRC procedures, such as measurement assessment and measurement reporting, L3 mobility, security key update, conditional handover, and DAPS handover in wireless networks.

[0024] Another object of embodiments herein is to configure LTM.

[0025] Another object of embodiments herein is to release the LTM.

[0026] Therefore, embodiments herein provide a method for handling lower layer triggered mobility (LTM) in a wireless network. The method includes receiving, by a UE, a radio resource control (RRC) reconfiguration from a network entity, the RRC reconfiguration including an LTM configuration having an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, the method includes, upon successful completion of the RRC reconfiguration, sending, by the UE, an RRC reconfiguration complete message to the network entity based on the RRC reconfiguration. Furthermore, the method includes, when the UE is measuring the same reference signal for an L3 measurement result and an LTM measurement, reusing, by the UE, one of: the L3 measurement result, and a portion of the L3 measurement result for the LTM measurement.

[0027] In various embodiments, when access stratum (AS) security has been activated, the network entity provides an LTM configuration in an RRC reconfiguration, the LTM configuration including one or more of an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration.

[0028] In various embodiments, when a signaling radio bearer 2 (SRB2) having at least one of a data radio bearer (DRB) is set and not suspended, or when one of a multicast radio bearer (MRB) and an SRB2 is set and not suspended, the network entity provides an LTM configuration in an RRC reconfiguration, the LTM configuration including one or more of an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration.

[0029] In various embodiments, a network entity provides LTM configuration for a secondary cell group (SCG) in New Radio Dual Connectivity (NR-DC) in an RRC reconfiguration in SRB3.

[0030] In various embodiments, the reference signals correspond to the same serving cell or the same neighbor cell.

[0031] Therefore, embodiments herein provide a method for handling lower layer triggered mobility in a wireless network. The method includes receiving, by a UE, an RRC reconfiguration, the RRC reconfiguration including information for releasing a LTM configuration. Furthermore, the method includes releasing, by the UE, the LTM configuration based on the received RRC reconfiguration.

[0032] Therefore, embodiments herein provide a method for handling lower layer triggered mobility. The method includes receiving, by a first network entity, a DAPS handover command from a second network entity in the first network entity. Furthermore, the method includes sending, by the first network entity, the DAPS handover command to a UE. Furthermore, the method includes releasing, by the first network entity, an LTM configuration before sending the DAPS handover command to the UE.

[0033] In various embodiments, the method includes skipping configuring, by the second network entity, LTM configuration until the DAPS handover is complete.

[0034] Therefore, embodiments herein provide a method for handling lower layer triggered mobility in a wireless network. The method includes sending, by a network entity, an RRC reconfiguration to a user equipment (UE), the RRC reconfiguration including an LTM configuration having one or more of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, the method includes receiving, by the network entity, an RRC reconfiguration completion from the UE based on the RRC reconfiguration.

[0035] Therefore, embodiments herein provide a UE comprising an LTM controller coupled to a processor and a memory. The LTM controller is configured to receive an RRC reconfiguration from a network entity, the RRC reconfiguration comprising an LTM configuration having at least one of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, upon successful completion of the RRC reconfiguration, the LTM controller is configured to send an RRC reconfiguration complete message to the network entity based on the RRC reconfiguration. Furthermore, the LTM controller is configured to, when the UE is measuring the same reference signal for both L3 measurement results and LTM measurements, reuse one of the following: the L3 measurement result and a portion of the L3 measurement result used for the LTM measurement.

[0036] Therefore, embodiments herein provide a UE comprising a LTM controller coupled to a processor and a memory. The LTM controller is configured to receive an RRC reconfiguration including information for releasing the LTM configuration. Furthermore, the LTM controller is configured to release the LTM configuration based on the RRC reconfiguration.

[0037] Therefore, embodiments herein provide a network entity comprising a length-time-limit (LTM) controller coupled to a processor and a memory. The LTM controller is configured to receive a DAPS handover command from a second network entity in a first network entity. Furthermore, the LTM controller is configured to send the DAPS handover command to a user equipment (UE). Furthermore, the LTM controller is configured to release an LTM configuration before sending the DAPS handover command to the UE.

[0038] Therefore, embodiments herein provide a network entity comprising an LTM controller coupled to a processor and a memory. The LTM controller is configured to send an RRC reconfiguration to a UE, the RRC reconfiguration comprising an LTM configuration having an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, the LTM controller is configured to receive an RRC reconfiguration complete from the UE based on the RRC reconfiguration.

[0039] These and other aspects of the embodiments herein will be better understood and appreciated when considered in conjunction with the following description and accompanying drawings. However, it should be understood that the following description, while indicating at least one embodiment and many specific details thereof, is intended to be illustrative and not restrictive. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

[0040] Advantageous Effects of the Invention

[0041] Aspects of the present disclosure are to address at least the above-mentioned problems and / or disadvantages and to provide at least the advantages described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings illustrate embodiments disclosed herein, and like reference numerals denote corresponding parts throughout the accompanying drawings. The embodiments disclosed herein will be better understood by the following description with reference to the accompanying drawings, wherein:

[0043] Figure 1 A wireless network for processing LTM according to embodiments disclosed herein is shown.

[0044] Figure 2 Various hardware components of a UE according to embodiments disclosed herein are shown.

[0045] Figure 3 Various hardware components of a network entity according to embodiments disclosed herein are shown.

[0046] Figure 4 and Figure 5 is a flow chart illustrating a method implemented by a UE for handling LTM in a wireless network according to an embodiment disclosed herein.

[0047] Figure 6 and Figure 7 is a flow chart illustrating a method implemented by a network entity for handling LTM in a wireless network according to embodiments disclosed herein.

[0048] Figure 8 Depicted is a process for performing LTM and L3 measurements according to embodiments disclosed herein.

[0049] Figure 9 The process of L3 HO and LTM interaction according to the embodiments disclosed herein is depicted.

[0050] Figure 10 Depicted is a process for updating security keys while processing an LTM according to embodiments disclosed herein.

[0051] Figure 11 The process of DAPS interacting with LTM according to the embodiments disclosed herein is depicted.

[0052] Figure 12 Depicted is a process for performing conditional mobility configuration according to embodiments disclosed herein.

[0053] Figure 13 The structure of a UE according to an embodiment of the present disclosure is shown.

[0054] Figure 14 The structure of a network entity according to the embodiments disclosed herein is shown. DETAILED DESCRIPTION

[0055] Aspects of the present disclosure address at least the above-mentioned problems and / or disadvantages and provide at least the advantages described below. Therefore, one aspect of the present invention is to provide a terminal in a wireless communication system and a communication method thereof.

[0056] Invention Mode

[0057] The embodiments herein and their various features and advantageous details will be explained more fully with reference to the non-limiting embodiments shown in the accompanying drawings and described in detail in the following description. Descriptions of well-known components and processing techniques are omitted so as not to unnecessarily obscure the embodiments herein. The examples used herein are intended only to facilitate an understanding of the embodiments herein and to further enable those skilled in the art to practice the embodiments herein. Therefore, these examples should not be construed as limiting the scope of the embodiments herein.

[0058] For purposes of interpreting this specification, the definitions (as defined herein) will apply, and where appropriate, terms used in the singular will also include the plural, and vice versa. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Unless otherwise indicated, the terms "including," "having," and "comprising" should be interpreted as open-ended terms.

[0059] As used herein, the words / phrases "exemplary," "example," "illustrative," "in an instance," "etc," "for example," and "i.e." merely mean "serving as an example, instance, or illustration." Any embodiment or implementation of the subject matter described herein using the words / phrases "exemplary," "example," "illustrative," "in an instance," "etc," "etc," "for example," and "i.e." are not necessarily to be construed as better or advantageous over other embodiments.

[0060] Embodiments herein can be described and illustrated according to the frame that performs the function or multiple functions.These frames can be referred to as managers, units, modules, hardware components, etc. in this article, and are physically implemented by analog and / or digital circuits, such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hard-wired circuits, etc., and can be optionally driven by firmware.For example, the circuit can be embodied in one or more semiconductor chips, or on a substrate support such as a printed circuit board. The circuit constituting the frame can be implemented by dedicated hardware, or by a processor (for example, one or more programmed microprocessors and related circuits), or by a combination of dedicated hardware that performs some functions of the frame and a processor that performs other functions of the frame. Without departing from the scope of this disclosure, each frame of the embodiment can be physically divided into two or more interacting and discrete frames. Similarly, without departing from the scope of this disclosure, the frame of the embodiment can be physically combined into more complex frames.

[0061] It should be noted that the elements in the accompanying drawings are shown for the purpose of this specification and ease of understanding and may not necessarily be drawn to scale. For example, a flow chart / sequence diagram illustrates the method in terms of the steps required to understand aspects of the embodiments disclosed herein. In addition, with respect to the construction of the device, one or more components of the device may be represented in the accompanying drawings by conventional symbols, and the accompanying drawings may only show those specific details relevant to understanding the present embodiment, so as not to obscure the drawings with details that are readily apparent to those of ordinary skill in the art having the benefit of the description herein. In addition, with respect to the system, one or more components / modules comprising the system may be represented in the accompanying drawings by conventional symbols, and the accompanying drawings may only show those specific details relevant to understanding the present embodiment, so as not to obscure the drawings with details that are readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0062] The accompanying drawings are used to facilitate easy understanding of various technical features, and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. Therefore, the present disclosure should be interpreted as extending to any modifications, equivalents, and alternatives other than those specifically listed in the accompanying drawings and corresponding descriptions. The use of words such as first, second, and third to describe components / elements / steps is for the purpose of this specification and should not be interpreted as sequential ordering / placement / appearance unless otherwise specified.

[0063] Embodiments herein provide a method for handling LTM in a wireless network. The method includes receiving, by a UE, an RRC reconfiguration from a network entity, the RRC reconfiguration including an LTM configuration having an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, the method includes, upon successful completion of the RRC reconfiguration, the UE sending an RRC reconfiguration complete message to the network entity based on the RRC reconfiguration. Furthermore, the method includes, when the UE is measuring the same reference signal for an L3 measurement result and an LTM measurement, the UE reusing one of the following: the L3 measurement result, and a portion of the L3 measurement result for the LTM measurement.

[0064] The proposed method can be used to handle the coexistence and interaction of LTM (L1 / L2 Triggered Mobility) with various RRC procedures, such as measurement assessment and measurement reporting, L3 mobility, security key update, conditional handover, and DAPS handover, without wasting signaling resources.

[0065] The following are the technical advantages of the proposed method:

[0066] 1. Reuse of Layer 3 measurements When a UE reuses L3 measurements for L1 measurement reporting, the UE does not have to perform L1 measurement and reporting separately, or can perform L1 measurement and reporting for a smaller number of LTM candidate cells. Reduced measurement and reporting will also save power and reduce processing complexity.

[0067] 2. One-time LTM release Releasing the LTM configuration all at once requires less signaling than releasing each configuration separately. This also enables smooth interoperability with Layer 3 handovers and interoperability with network nodes that do not support LTM—they only need to implement a flag to release the entire LTM configuration, rather than using the full configuration.

[0068] 3. DAPS and LTM interoperability : Makes implementation in UE and network nodes simpler. The proposed method can be used to avoid complex interworking between the gNB CU and gNB DU, and between different layers / controllers in the UE protocol stack.

[0069] 4. AS security and LTM configuration behind SRB2 / DRB or SRB2 / MRB The proposed method can be used to prevent man-in-the-middle attacks and other security issues. For example, without the proposed method, an intruder could know the UE's radio bearer configuration, which could lead to privacy violations. This also simplifies UE and network implementations because additional checks for complex security processing can be reduced.

[0070] 5. Using SRB3The proposed method can be used to simplify the LTM configuration within the SN. This also reduces the inter-node signaling overhead between the MN and the SN as well as the signaling overhead on the air interface.

[0071] Referring now to the drawings and more particularly to Figures 1 to 12 , where like reference numerals represent corresponding features consistently throughout the drawings, illustrates at least one embodiment.

[0072] Figure 1 A wireless network (1000) for processing LTM according to embodiments disclosed herein is shown. The wireless network (1000) may be, for example, but not limited to, a fourth generation (4G) network, a fifth generation (5G) network, an open radio access network (ORAN), etc. In various embodiments, the wireless network (1000) includes a UE (100) and a network entity (200). The UE (100) may be, for example, but not limited to, a laptop, a smartphone, a desktop computer, a notebook computer, a device-to-device (D2D) device, a vehicle-to-everything (V2X) device, a foldable phone, a smart TV, a tablet, an immersive device, and an Internet of Things (IoT) device. The network entity (200) may be, for example, but not limited to, a gNB, an eNB, a new radio (NR) transceiver, etc.

[0073] The UE (100) receives an RRC reconfiguration from a network entity (200), the RRC reconfiguration including an LTM configuration including an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, upon successful completion of the RRC reconfiguration, the UE (100) transmits an RRC reconfiguration complete message to the network entity (200) based on the RRC reconfiguration. Furthermore, when the UE (100) is measuring the same reference signal for an L3 measurement result and an LTM measurement, the UE (100) reuses one of the following: the L3 measurement result and a portion of the L3 measurement result for the LTM measurement.

[0074] In another embodiment, the UE (100) receives an RRC reconfiguration including information for releasing the LTM configuration. Based on the received RRC reconfiguration, the UE (100) releases the LTM configuration.

[0075] In various embodiments, the network entity (200) triggers a DAPS handover command to the UE (100) to another network entity (not shown). In addition, the network entity (200) releases the LTM configuration before triggering the DAPS handover command to the UE (100).

[0076] In another embodiment, after activating AS security, the network entity (200) sends an RRC reconfiguration to the UE (100), the RRC reconfiguration including an LTM configuration including an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, the network entity (200) receives an RRC reconfiguration completion from the UE (100) based on the RRC reconfiguration.

[0077] All the following embodiments may be based on the capabilities of the UE reported to the network entity (200). There may be some UEs that do not support the provided capabilities. The embodiments herein show the following example sequence (SEQUENCE) that can be used to configure LTM.

[0078]

[0079]

[0080] In various embodiments, a network entity (e.g., a gNB) (200) sends an LTM configuration to a UE (100) in an RRC message. The gNB centralized unit (CU) may also send an LTM configuration including an LTM measurement configuration to the gNB distributed unit (DU). The LTM measurement configuration sent from the gNB CU to the gNBDU includes an L1 measurement configuration for LTM, including measurement objects for LTM measurement (such as frequencies to be measured, cells to be measured for LTM measurement), measurement identifiers for LTM measurement, measurement gap configurations for LTM measurement, and report configurations for LTM measurement including measurement filters / thresholds / offsets. The LTM measurement configuration may also include a CSI resource configuration for LTM.

[0081] Measurement configuration : The gNB may configure different measurement configurations for the UE (100) for Layer 3 mobility (e.g., using the MeasConfig IE in R17 NR) and LTM. The UE (100) has been configured with different measurement configurations for Layer 3 mobility (measurements configured / performed / reported for Layer 3 mobility (e.g., configured via the R17 MeasConfig IE, hereinafter referred to as L3 measurements) and LTM.

[0082] Measurement configuration (measurements configured / performed / reported for LTM, hereinafter referred to as LTM measurements), performing both L3 measurements and LTM measurements (such as Figure 8 depicted).

[0083] In various embodiments, when a UE (100) is configured to perform L3 measurements and LTM measurements on the same frequency, the UE (100) performs L3 measurements on all cells on the frequency regardless of whether the cells are configured for LTM measurements, unless explicitly prohibited or the UE is configured to perform measurements only on specific cells. For L3 measurements, the use of an excludedCell list (configured using excludedCellsToAddModList / excludedCellsToRemoveList) and the configuration of measuring only specific cells (allowedCells list) (accomplished using allowedCellsToAddModList / allowedCellsToRemoveList) are explicitly prohibited.

[0084] When measuring the same reference signal for both L3 measurement and LTM measurement (e.g., in the same serving cell or neighbor cell), the UE (100) reuses the entire LTM measurement result or a portion of the LTM measurement result for layer 3 measurement, or reuses the L3 measurement result or a portion of the L3 measurement result for LTM measurement. That is, when the UE (100) is configured for L3 measurement and LTM measurement, the UE (100) avoids repeated measurements of the same cell and the same reference signal for both LTM measurement and L3 measurement. In the example, the UE (100) can perform layer 1 measurement for LTM. The UE (100) applies an L3 filter and reports the measurement to the network entity (200) via an L3 measurement report (Meas Report). The UE (100) also sends the layer 1 measurement result to the gNB via a MAC CE and an L3 measurement report in the RRC based on the same measurement set available.

[0085] In various embodiments, the gNB CU includes any LTM candidate cells for which the UE (100) has been configured in the excludedCells list, or includes only cells other than the LTM candidate cells for which the UE (100) has been configured in the allowedCells list to restrict the UE (100) from performing L3 measurements on the same cells for which LTM has been configured.

[0086] In various embodiments, the UE (100) is configured to perform L3 measurements on the frequency and has received an LTM configuration that includes LTM candidate cells. The UE (100) excludes performing L3 measurements on the LTM candidate cells. The L3 measurement configuration and the LTM configuration may come from different RRC messages, such as RRC reconfiguration or RRC recovery, or different RRC reconfiguration messages. In addition, the UE (100) excludes reporting L3 measurements on the LTM candidate cells on the frequency (e.g., Figure 8As depicted). In the example, the UE (100) (e.g., NRUE (100, etc.) has been configured with MeasConfig with a measurement object having an SSB frequency F1. On the same frequency F1, the UE (100) has been configured for LTM with LTM candidate cells C1 and C2. When performing measurements for L3 mobility or reporting measurements, the UE (100) does not consider C1 and C2 even if C1 and C2 are detected. Considering that the UE (100) has detected C1, C2, C3, and C4 on F1, the UE (100) only performs and reports measurements for C3 and C4. In other words, in this embodiment, the UE (100) behaves as if it has received LTM candidate cells as excludedCells for L3 measurement. That is, the UE (100) treats any LTM candidate cell as excludedCells for L3 measurement even if it is not in the received excludedCellsList.

[0087] L3 Mobility and LTM :The UE (100) performs L3 mobility when it receives an RRC reconfiguration message requiring the UE (100) to perform a handover, or when it performs a conditional reconfiguration (e.g., CHO, CPA (conditional PS Cell add), or CPC). In NR, the RRC reconfiguration message requiring the UE (100) to perform a handover may be an RRCReconfiguration message (including reconfigurationWithSync) and spCellConfigCommon in reconfigurationWithSync (including a physical cell identifier (physCellId)). Once the UE (100) moves to the target cell, the L3 mobility ends successfully. In most cases, the UE (100) can perform random access when moving to the target cell, except in certain cases, such as when the UE (100) is in a deactivated SCG in the target cell, or when RACHless handover is configured for a non-terrestrial network cell. The UE (100) applies the target configuration during the handover execution. In a DAPS handover, the UE (100) may retain both the source and target configurations until the target configuration is explicitly released by the network entity (200). L3 mobility may fail if the UE (100) does not successfully move to the target cell, for example due to a handover failure or due to an inability to apply the provided configuration.

[0088] The UE (100) performs LTM upon receiving a cell handover command from a network entity (200) (and may also decide to perform a cell handover if certain configured criteria are matched). It is also possible that if the UE (100) selects a cell as a candidate cell for LTM, then LTM triggering occurs (for example) due to other actions rather than receiving an L1 or L2 message from a gNB in the event of a radio link failure, the UE (100) may behave as if LTM was triggered, i.e., perform actions when LTM was triggered, if the network is configured to do so. If the UE (100) has successfully handed over to the target cell, then LTM is successfully completed. The UE (100) may successfully perform random access or may make an uplink transmission (on an L1 channel, such as a physical uplink control channel (PUCCH) / physical uplink shared channel (PUSCH)) to indicate the successful completion of LTM.

[0089] When performing L3 mobility, the UE (100) cancels (if any) the UL MAC CE triggered for reporting LTM measurements. That is, upon receiving an RRC message for L3 mobility or performing conditional handover, the UE (100) cancels the UL MAC CE triggered for sending LTM measurements to the gNB. This process is Figure 9 Depicted in.

[0090] When performing L3 mobility, the UE (100) cancels (if any) a Scheduling Request (SR) or a Buffer Status Report (BSR) triggered for reporting LTM measurements. After L3 handover, the UE (100) cancels (if any) a SR or BSR triggered for sending LTM measurements to the gNB.

[0091] When performing MCG L3 mobility, the UE (100) cancels (if any) the UL MAC CE triggered for reporting LTM measurements, the SR triggered for reporting LTM measurements to the primary network (MN) (instead of to the secondary network (SN)), and the triggered BSR. Alternatively, when performing MCG L3 mobility, the UE (100) cancels (if any) the UL MAC CE triggered for reporting LTM measurements, and the SR and BSR for reporting LTM measurements to any one of the MN and the SN.

[0092] When performing SCG L3 mobility, the UE (100) cancels (if any) the UL MAC CE triggered for reporting LTM measurements, the SR triggered for reporting LTM measurements to the SN (instead of the MN), and the triggered BSR. Alternatively, when performing SCG L3 mobility, the UE (100) cancels (if any) the UL MAC CE triggered for reporting LTM measurements, and the SR and BSR for reporting LTM measurements to any one of the SN and the MN.

[0093] When performing L3 mobility, the UE (100) stops LTM measurement and LTM measurement evaluation. When performing MCG L3 mobility, the UE (100) stops LTM measurement and measurement evaluation for the MCG but not for the SCG. Alternatively, when performing MCG L3 mobility, the UE (100) stops LTM measurement and measurement evaluation for the MCG and also stops LTM measurement and measurement evaluation for the SCG.

[0094] When performing SCG L3 mobility, the UE (100) stops LTM measurement and measurement evaluation for the SCG instead of the MCG. Alternatively, when performing SCG L3 mobility, the UE (100) stops LTM measurement and measurement evaluation for the SCG and also stops LTM measurement and measurement evaluation for the MCG.

[0095] When performing LTM, the UE (100) stops layer 3 measurements and measurement evaluations for layer 3 mobility. When performing MCG LTM, the UE (100) stops layer 3 measurements and measurement evaluations for the MCG but not for the SCG. Alternatively, when performing MCG LTM, the UE (100) stops layer 3 measurements and measurement evaluations for the MCG and also stops layer 3 measurements and measurement evaluations for the SCG.

[0096] When performing SCG LTM, the UE (100) stops layer 3 measurement and measurement evaluation for the SCG instead of the MCG. Alternatively, when performing SCG LTM, the UE (100) stops layer 3 measurement and measurement evaluation for the SCG and also stops layer 3 measurement and measurement evaluation for the MCG.

[0097] In various embodiments, when performing layer 3 mobility, the UE (100) clears the entire LTM configuration.

[0098] In another embodiment, when performing layer 3 mobility, a portion of the LTM configuration is cleared and a portion of the LTM configuration is retained. The cleared configuration may include some LTM candidate cell configurations and LTM reference configurations. In various embodiments, when performing layer 3 mobility, the UE (100) retains the LTM measurement configuration, such as the frequency to be measured for LTM, the measurement report configuration for LTM, and the measurement identifier for LTM.

[0099] In various embodiments, the UE (100) receives information from the gNB regarding whether the LTM configuration (in this embodiment, the LTM configuration may also be a part of the LTM configuration) needs to be released or retained. The UE (100) may receive an RRC IE such as a flag, and if the flag is set or set to true, the UE (100) releases the LTM configuration when performing L3 mobility. If the flag is set to false or not set, the UE (100) retains the LTM configuration. Alternatively, the UE (100) may receive an RRC IE (such as a flag), and if set or set to true, the UE (100) releases the LTM configuration when performing L3 mobility, and if not set or set to false, the UE (100) retains the LTM configuration when performing L3 mobility.

[0100] In various embodiments, when performing layer 3 inter-gNB mobility, the UE (100) clears the LTM configuration.

[0101] In various embodiments, when performing Layer 3 inter-gNB mobility, a portion of the LTM configuration is autonomously cleared, and the portion of the LTM configuration is retained unless explicitly released by the gNB. The cleared configuration may include candidate cell configuration and LTM reference configuration. In various embodiments, when performing Layer 3 inter-gNB mobility, the UE (100) retains the LTM measurement configuration (e.g., frequencies to be measured for LTM, measurement report configuration for LTM, and measurement identifiers for LTM) unless explicitly released by the gNB.

[0102] LTM and security key updates In various embodiments, the UE (100) clears the LTM configuration upon security key update. In various embodiments, the NR UE (100) clears the LTM candidate cell configuration upon receiving an RRCRe configuration including masterKeyUpdate or nextHopChainingCount or keySetChangeIndicator. Figure 10 Describes the process of updating security keys.

[0103] In various embodiments, the NR UE (100) clears the LTM candidate cell configuration when receiving an RRCReconfiguration including masterKeyUpdate or nextHopChainingCount or keySetChangeIndicator during handover (i.e., clears when the primary cell changes).

[0104] In various embodiments, the NR UE (100) clears the LTM candidate cell configuration upon receiving an RRCReconfiguration including masterKeyUpdate or nextHopChainingCount or keySetChangeIndicator, and the physCellId in the ServingCellConfigCommon in the reconfigurationWithSync in the spCellConfig includes a new physical cell identifier instead of the current cell. In various embodiments, the NR UE (100) clears the LTM reference configuration upon receiving an RR CReconfiguration including masterKeyUpdate or nextHopChainingCount or keySetChangeIndicator, and the physCellId in the ServingCellConfigCommon in the reconfigurationWithSync in the spCellConfig includes a new physical cell identifier instead of the current cell.

[0105] In various embodiments, the NR UE (100) clears the MCG LTM candidate cell configuration upon receiving an RRCReconfiguration including a masterKeyUpdate or nextHopChainingCount or keySetChangeIndicator, and the physCellId in the ServingCellConfigCommon in the reconfigurationWithSync in the spCellConfig of the MCG includes a new physical cell identifier instead of the current cell. In various embodiments, the NR UE (100) clears the MCG LTM reference configuration upon receiving an RRCReconfiguration including a masterKeyUpdate or nextHopChainingCount or keySetChangeIndicator, and the physCellId in the ServingCellConfigCommon in the reconfigurationWithSync in the spCellConfig of the MCG includes a new physical cell identifier instead of the current cell.

[0106] In various embodiments, the NR UE (100) clears the SCG LTM candidate cell configuration upon receiving an RRCReconfiguration including an sk-counter (SN counter), and the physCellId in the ServingCellConfigCommon in the reconfigurationWithSync in the spCellConfig of the SCG includes a new physical cell identifier instead of the current cell. In various embodiments, the NR UE (100) clears the SCG LTM reference configuration upon receiving an RRCReconfiguration including an sk-counter (SN counter), and the physCellId in the ServingCellConfigCommon in the reconfigurationWithSync in the spCellConfig of the SCG includes a new physical cell identifier instead of the current cell.

[0107] In various embodiments, the UE (100) clears the LTM candidate cell configuration and / or the LTM reference configuration upon security key update. In various embodiments, the UE (100) clears the MCG LTM candidate cell configuration and / or the LTM reference configuration upon MCG security key update. In various embodiments, the UE (100) clears the SCG LTM candidate cell configuration and / or the LTM reference configuration upon SCG security key update.

[0108] LTM and Inter-RAT HO : Upon successful completion of mobility from NR, the NR UE (100) releases the LTM configuration, which includes the LTM candidate cell configuration, the LTM reference configuration, the LTM measurement configuration, etc.

[0109] In various embodiments, for handover from Long Term Evolution (LTE) or other RATs to NR, the gNB does not include LTM configuration.

[0110] LTM and DAPS : Figure 11The process of DAPS and LTM interaction is described. In various embodiments, if the UE (100) performs DAPS handover, the UE (100) releases the LTM configuration configured by the source gNB, the LTM configuration including at least some of the LTM measurement configuration, LTM candidate cell configuration, LTM reference configuration, etc. In various embodiments, if a DAPS bearer is configured, the gNB skips configuring the LTM configuration (including at least one of the LTM measurement configuration, LTM candidate cell configuration, LTM reference configuration, etc.). The gNB releases the LTM configuration (if configured) when configuring the DAPS bearer and adds the LTM configuration again when releasing the DAPS bearer. In addition, the gNB can release the DAPS bearer while performing the LTM configuration.

[0111] In various embodiments, the source gNB releases the LTM configuration before sending a DAPS handover command to the UE (100). The target gNB skips configuring the LTM configuration until the DAPS handover is complete.

[0112] Example specification changes for the above embodiment according to 3gpp specification TS 38.300 are given below:

[0113] 1. Only the source and target PCells are used during DAPS handover. Carrier aggregation (CA), dual connectivity (DC), supplementary uplink (SUL), multiple TRPs, Ethernet header compression (EHC), CHO, unified data fusion (UDC), NR side link configuration, vehicle-to-everything (V2X) side link configuration and LTM configuration are released by the source gNB before the handover command is sent to the UE (100) and are not configured by the target gNB until the DAPS handover has been completed (i.e. at the earliest in the same message that releases the source PCell).

[0114] In an alternative embodiment, the gNB may configure the DAPS bearer and LTM configuration to the UE (100) simultaneously. In this case, upon receiving a handover command requesting a DAPS handover, the UE (100) suspends LTM measurements, evaluations, and reporting, stops sending any LTM measurements toward the source cell, and stops receiving cell handover commands from the source cell. When both the DAPS bearer and LTM configuration are configured, if the DAPS handover is successful, the UE (100) sends a UL MAC CE for reporting LTM measurements solely to the target gNB, rather than to the source gNB. Furthermore, upon a successful DAPS handover, even if the source configuration is not released, a DL MAC CE for LTM cell handover is sent from the target gNB (rather than from the source gNB) to the UE (100). When the source configuration is released, the UE (100) releases the LTM configuration. If the DAPS handover fails, the UE (100) resumes LTM measurements, evaluates, and reports LTM measurements to the source cell, and may receive a cell handover command from the source cell.

[0115] In another embodiment, the source gNB releases the LTM configuration on the source cell before the LTM command is sent, but the target gNB can configure the LTM configuration in the handover command.

[0116] LTM and SRB3 : In various embodiments, the gNB includes the LTM configuration in the RRC reconfiguration included in SRB3 even if the RRC reconfiguration is not received through DLInformationTransferMRDC.

[0117] This can be reflected in TS 38.331 as follows:

[0118] a. In (NG)EN-DC and NR-DC, SRB3 can be used for measurement configuration and reporting, for UE (100) assisted (re)configuration and reporting to save power, for IP address (re)configuration and reporting for IAB nodes, to (re)configure MAC, RLC, BAP, physical layer and RLF timers and constants configured by SCG, and to reconfigure PDCP for DRBs associated with S-KgNB or SRB3, and to reconfigure SDAP for DRBs associated with S-KgNB in NGEN-DC and NR-DC, and to add / modify / release conditional PSCell change configuration and configure LTM configuration, provided that the (re)configuration does not require any MN participation and RRC messages are sent between MN and UE (100) during fast MCG link recovery. Under (NG)EN-DC and NR-DC, only measConfig, radioBearerConfig, conditionalReconfiguration, bap-Config, iab-IP-AddressConfigurationList, otherConfig, LTM-Config and / or secondaryCellGroup are included in the RRCReconfiguration received over SRB3, unless the RRCReconfiguration is received in DLInformationTransferMRDC.

[0119] Conditions for LTM configuration and measurement reporting In various embodiments, the gNB includes LTM configuration in the RRC reconfiguration only when AS security has been activated. In various embodiments, the gNB includes LTM configuration in the RRC reconfiguration only when SRB2 with at least one of the DRBs is set and not suspended, or when a multicast MRB or (for integrated access and backhaul (IAB)) SRB2 is set and not suspended.

[0120] In various embodiments, the gNB includes the LTM candidate cell configuration in the RRC reconfiguration only when AS security is activated. In various embodiments, the gNB includes the LTM candidate cell configuration in the RRC reconfiguration only when SRB2 with at least one of a DRB or a multicast MRB is set and not suspended. In various embodiments, the gNB includes the LTM candidate cell configuration in the RRC reconfiguration only when a multicast MRB or (for IAB) SRB2 is set and not suspended.

[0121] In various embodiments, the gNB includes LTM measurement configuration in the RRC reconfiguration even if AS security has not been activated. In various embodiments, the UE (100) reports LTM measurements (e.g., sends an UL MAC CE including LTM measurements) only after AS security is activated, even if configured before AS security is activated.

[0122] In various embodiments, the gNB may include LTM measurement configuration in the RRC reconfiguration regardless of whether SRB2 and DRB or multicast MRB or (for IAB) SRB2 are set or suspended. In various embodiments, the gNB includes LTM candidate cell configuration in the RRC reconfiguration regardless of whether SRB2 and DRB or multicast MRB or (for IAB) SRB2 are set and not suspended.

[0123] In various embodiments, when sending LTM configuration to UE (100), MN does not include MRDC-SecondaryCellGroupConfig. UE (100) retains the secondary cell group configuration when LTM is executed, regardless of whether the reference configuration is configured or whether the LTM configuration includes fullconfig.

[0124] LTM and CHO In various embodiments, the gNB excludes the inclusion of the conditionalReconfiguration IE (as defined in TS 38.331) within the LTM configuration in the RRC reconfiguration message. In various embodiments, the gNB excludes the inclusion of the LTM configuration within the conditionalReconfiguration IE in the RRC reconfiguration message.

[0125] In various embodiments, if the gNB has configured LTM candidate cells for the UE (100), the gNB excludes configuring conditional reconfiguration for any cell. The gNB releases the LTM candidate cells before / when configuring any candidate cells for conditional reconfiguration.

[0126] In various embodiments, if the gNB has already configured LTM candidate cells for the UE (100), the gNB excludes configuring any LTM candidate cells. The gNB releases any configured candidate cells for conditional reconfiguration before / when configuring any LTM candidate cells.

[0127] In various embodiments, the gNB excludes configuring both the LTM candidate cell configuration (LTMConfig) and the conditional reconfiguration configuration for the same candidate cell. In this example, if the gNB has configured cells C1, C2, and C3 as LTM candidate cells for frequency F1, the gNB excludes cells C1, C2, and C3 for F1 from the list of cells to be configured for conditional handover. Similarly, if the SN in NR-NRDC configures cells C4, C5, and C6 for frequency F2 as LTM candidate cells, the SN gNB excludes cells C4, C5, and C6 for frequency F2 from the list of cells to be configured for conditional PSCell change.

[0128] Figure 2 Various hardware components of a UE (100) according to embodiments disclosed herein are shown. In various embodiments, the UE (100) includes a processor (110), a communicator (120), a memory (130), and an LTM controller (140). The processor (110) is coupled to the communicator (120), the memory (130), and the LTM controller (140).

[0129] The LTM controller (140) receives an RRC reconfiguration from a network entity (200), the RRC reconfiguration including an LTM configuration including an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, upon successful completion of the RRC reconfiguration, the LTM controller (140) transmits an RRC reconfiguration completion message to the network entity (200) based on the RRC reconfiguration. Furthermore, when the UE (100) is measuring the same reference signal for both an L3 measurement result and an LTM measurement, the LTM controller (140) reuses one of the following: the L3 measurement result, and a portion of the L3 measurement result for the LTM measurement.

[0130] In another embodiment, the LTM controller (140) receives an RRCReconfiguration including information for releasing the LTM configuration. Based on the received RRC reconfiguration, the LTM controller (140) releases the LTM configuration.

[0131] The LTM controller (140) is implemented by analog and / or digital circuits, such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hard-wired circuits, etc., and may optionally be driven by firmware.

[0132] The processor (110) may include one or more processors. The one or more processors may be general-purpose processors (such as a central processing unit (CPU), an application processor (AP), etc.), graphics processing units (such as a graphics processing unit (GPU), a visual processing unit (VPU)), and / or AI-specific processors (such as a neural processing unit (NPU)). The processor (110) may include multiple cores and be configured to execute instructions stored in the memory (130).

[0133] In addition, the processor (110) is configured to execute instructions stored in the memory (130) and perform various processes. The communicator (120) is configured to communicate internally between internal hardware components and to communicate with external devices via one or more networks. The memory (130) also stores instructions to be executed by the processor (110). The memory (130) may include a non-volatile storage element. Examples of such non-volatile storage elements may include a magnetic hard disk, an optical disk, a floppy disk, a flash memory, or an electrically programmable memory (EPROM) or an electrically erasable programmable memory (EEPROM) memory. In addition, in some examples, the memory (130) may be considered a non-transitory storage medium. The term "non-transitory" may mean that the storage medium is not embodied in a carrier wave or propagating signal. However, the term "non-transitory" should not be interpreted as meaning that the memory (130) is non-removable. In some examples, the non-transitory storage medium may store (e.g., in random access memory (RAM) or cache) data that may change over time.

[0134] In various embodiments, the communicator (120) includes electronic circuitry dedicated to implementing standards for wired or wireless communication. The communicator (120) is configured to communicate internally between internal hardware components of the UE (100) and to communicate with external devices over one or more networks.

[0135] although Figure 2 Various hardware components of the UE (100) are shown, but it should be understood that other embodiments are not limited thereto. In other embodiments, the UE (100) may include fewer or greater numbers of components. Furthermore, the labels or names of the components are for illustrative purposes only and do not limit the scope of the present disclosure. One or more components may be combined to perform the same or substantially similar functions in the UE (100).

[0136] Figure 3Various hardware components of a network entity (200) according to embodiments disclosed herein are shown. In various embodiments, the network entity (200) includes a processor (210), a communicator (220), a memory (230), and an LTM controller (240). The processor (210) is coupled to the communicator (220), the memory (230), and the LTM controller (240).

[0137] The LTM controller (240) of the first network entity receives a DAPS handover command in the first network entity from the second network entity. The DAPS handover command is received by the first network entity as part of a handover request acknowledgment sent from the second network entity in response to a handover request sent by the first network entity for an inter-network node handover. The first network entity may also act as the second network entity when the handover is an intra-network node handover. In addition, the LTM controller (240) of the first network entity sends the DAPS handover command to the UE (100). In addition, the LTM controller (240) of the first network entity releases the LTM configuration before sending the DAPS handover command to the UE (100). In addition, the LTM controller (240) of the second network entity skips configuring the LTM configuration until the DAPS handover is completed.

[0138] In another embodiment, the LTM controller (240) sends an RRC reconfiguration to the UE (100), the RRC reconfiguration including an LTM configuration including an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. Furthermore, the LTM controller (240) receives an RRC reconfiguration completion from the UE (100) based on the RRC reconfiguration.

[0139] In another embodiment, when AS security has been activated, the LTM controller (240) provides an LTM configuration in an RRC reconfiguration, the LTM configuration including an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration.

[0140] In another embodiment, when a signaling radio bearer 2 (SRB2) having at least one of the DRBs is set and not suspended, or when one of the MRB and the SRB2 is set and not suspended, the LTM controller (240) provides an LTM configuration including an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration in an RRC reconfiguration.

[0141] In another embodiment, the LTM controller (240) provides LTM configuration for the SCG in NR-DC in the RRC reconfiguration included in SRB3.

[0142] The LTM controller (240) is implemented by analog and / or digital circuits, such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hard-wired circuits, etc., and may optionally be driven by firmware.

[0143] The processor (210) may include one or more processors. The one or more processors may be general-purpose processors (such as a central processing unit (CPU), an application processor (AP), etc.), graphics processing units (such as a graphics processing unit (GPU), a visual processing unit (VPU)), and / or AI-specific processors (such as a neural processing unit (NPU)). The processor (210) may include multiple cores and be configured to execute instructions stored in the memory (230).

[0144] In addition, the processor (210) is configured to execute instructions stored in the memory (230) and perform various processes. The communicator (220) is configured to communicate internally between internal hardware components and to communicate with external devices via one or more networks. The memory (230) also stores instructions to be executed by the processor (210). The memory (230) may include a non-volatile storage element. Examples of such non-volatile storage elements may include a magnetic hard disk, an optical disk, a floppy disk, a flash memory, or an electrically programmable programmable memory (EPROM) or an electrically erasable programmable programmable memory (EEPROM). In addition, in some examples, the memory (230) may be considered a non-transitory storage medium. The term "non-transitory" may mean that the storage medium is not embodied in a carrier wave or propagating signal. However, the term "non-transitory" should not be interpreted as meaning that the memory (230) is non-removable. In some examples, the non-transitory storage medium may store (e.g., in random access memory (RAM) or cache) data that may change over time.

[0145] In various embodiments, the communicator (220) includes electronic circuitry dedicated to implementing standards for wired or wireless communication. The communicator (220) is configured to communicate internally between internal hardware components of the UE (100) and to communicate with external devices over one or more networks.

[0146] although Figure 3 Various hardware components of the network entity (200) are shown, but it should be understood that other embodiments are not limited thereto. In other embodiments, the network entity (200) may include fewer or greater numbers of components. Furthermore, the labels or names of the components are for illustrative purposes only and do not limit the scope of the present disclosure. One or more components may be combined to perform the same or substantially similar functions in the network entity (200).

[0147] Figure 4 and Figure 5 Flowcharts (400 and 500) illustrate methods implemented by a UE (100) for handling LTM in a wireless network (1000) according to embodiments disclosed herein.

[0148] like Figure 4 As shown, operations (402-406) are processed by the LTM controller (140). At 402, the method includes receiving an RRC reconfiguration from a network entity (200), the RRC reconfiguration including an LTM configuration having an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. At 404, the method includes sending an RRC reconfiguration completion to the network entity (200) based on the RRC reconfiguration when the RRC reconfiguration is successfully completed. At 406, the method includes reusing one of the following: the L3 measurement result, and a portion of the L3 measurement result for the LTM measurement when the UE (100) is measuring the same reference signal for the L3 measurement result and the LTM measurement.

[0149] like Figure 5 As shown, operations (502 and 504) are handled by the LTM controller (140). At 502, the method includes receiving an RRCReconfiguration including information for releasing the LTM configuration. At 504, the method includes releasing the LTM configuration based on the received RRC reconfiguration.

[0150] Figure 6 and Figure 7 are flow charts (600 and 700) illustrating methods implemented by a network entity (200) for handling LTM in a wireless network (1000) according to embodiments disclosed herein.

[0151] like Figure 6 As shown, operations (602-608) are processed by the controller (240). At 602, the method includes receiving, by the first network entity, a DAPS handover command in the first network entity (200) from the second network entity. The DAPS handover command may be received by the first network entity as part of a handover request acknowledgment sent from the second network entity in response to a handover request sent by the first network entity for an inter-network node handover. The first network entity may also act as the second network entity when the handover is an intra-network node handover. At 604, the method includes sending, by the first network entity, a DAPS handover command to the UE (100). At 606, the method includes releasing, by the first network entity, an LTM configuration before sending the DAPS handover command to the UE (100). At 608, the method includes skipping configuring the LTM configuration by the second network entity until the DAPS handover is completed. In NR, the first network entity is a source gNB and the second network entity is a target gNB.

[0152] like Figure 7 As shown, operations (702 and 704) are processed by the LTM controller (240). At 702, the method includes sending an RRC reconfiguration to the UE (100) after AS security is activated and in at least one of the following situations: when SRB2 with at least one of the DRBs is set and not suspended, or when one of the MRB and SRB2 is set and not suspended. The RRC reconfiguration includes an LTM configuration including an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration. At 704, the method includes receiving an RRC reconfiguration completion from the UE (100) based on the RRC reconfiguration.

[0153] Figure 8 A process for performing LTM and L3 measurements according to embodiments disclosed herein is described. In step 1, the RRC layer of the gNB sends an RRC reconfiguration including an LTM configuration and an L3 measurement configuration to the RRC layer of the UE (100). In step 2, the RRC layer of the UE (100) sends an RRC reconfiguration complete to the RRC layer of the gNB. In step 3, the L1 / L2 and RRC layers of the UE (100) perform LTM (L1) measurements on the candidate cell. In addition, the L1 / L2 and RRC layers of the UE (100) skip L3 measurements on the LTM candidate.

[0154] Figure 9 The process of L3 HO and LTM interaction according to the embodiments disclosed herein is described. In step 1, the RRC layer of the gNB sends an RRC reconfiguration including LTM configuration and L3 measurement configuration to the RRC layer of the UE (100). In step 2, the RRC layer of the UE (100) sends an RRC reconfiguration completion to the RRC layer of the gNB. In step 3, the RRC layer of the UE (100) sends an RRC measurement report to the RRC layer of the gNB. In step 4, the RRC layer of the gNB sends an RRC reconfiguration for handover to the RRC layer of the UE (100). In step 5, the L1 / L2 layer of the UE (100) cancels any triggered UL MAC CE for LTM measurement reporting and any SR or BSR for LTM measurement reporting. In addition, the L1 / L2 layer of the UE (100) stops LTM measurement and evaluation.

[0155] Figure 10 A process for updating security keys while processing LTM according to an embodiment disclosed herein is described. In step 1, the RRC layer of the gNB sends an RRC reconfiguration including LTM configuration and L3 measurement configuration to the RRC layer of the UE (100). In step 2, the RRC layer of the UE (100) sends an RRC reconfiguration complete to the RRC layer of the gNB. In step 3, the L1 / L2 and RRC layers of the UE (100) clear the LTM candidate cell configuration according to an embodiment.

[0156] Figure 11 The process of DAPS interacting with LTM according to the embodiments disclosed herein is depicted.

[0157] In step 1, the RRC layer of the gNB sends an RRC reconfiguration including LTM configuration and L3 measurement configuration to the RRC layer of the UE (100). In step 2, the RRC layer of the UE (100) sends an RRC reconfiguration complete to the RRC layer of the gNB. In step 3, the RRC layer of the UE (100) sends an RRC measurement report to the RRC layer of the gNB. In step 4, the RRC layer of the gNB sends an RRC reconfiguration for removing the LTM configuration or part of the LTM configuration to the RRC layer of the UE (100). In step 5, the RRC layer of the UE (100) sends an RRC reconfiguration complete to the RRC layer of the gNB. In step 6, the RRC layer of the gNB sends an RRC reconfiguration including a DAPS bearer and a target RRC reconfiguration without LTM configuration to the RRC layer of the UE (100). In step 7, the RRC layer of the UE (100) sends an RRC reconfiguration complete to the RRC layer of the gNB.

[0158] Figure 12 A process for performing conditional mobility configuration according to an embodiment disclosed herein is described. In step 1, the RRC layer of the gNB sends an RRC reconfiguration including LTM configuration and conditional mobility configuration. The LTM candidates and conditional mobility candidates are disjoint sets. In step 2, the RRC layer of the UE (100) sends an RRC reconfiguration complete to the RRC layer of the gNB.

[0159] The various actions, behaviors, blocks, steps, etc. in the flowcharts (400-700) may be performed in the order presented, in a different order, or simultaneously. Furthermore, in some embodiments, some actions, behaviors, blocks, steps, etc. may be omitted, added, modified, skipped, etc. without departing from the scope of the present disclosure.

[0160] Figure 13 The structure of a UE according to an embodiment of the present disclosure is shown.

[0161] like Figure 13 As shown, the UE according to the embodiment may include a transceiver 1310, a memory 1320, and a processor 1330. The transceiver 1310, the memory 1320, and the processor 1330 of the UE may operate according to the communication method of the above-mentioned UE. However, the components of the UE are not limited thereto. For example, the UE may include more or fewer components than the above-mentioned components. In addition, the processor 1330, the transceiver 1310, and the memory 1320 may be implemented as a single chip. In addition, the processor 1330 may include at least one processor. In addition, Figure 13 The UE corresponds to Figure 2UE.

[0162] The transceiver 1310 is collectively referred to as a UE receiver and a UE transmitter, and can transmit and receive signals to and from a base station or network entity. Signals transmitted to and received from a base station or network entity may include control information and data. The transceiver 1310 may include an RF transmitter for up-converting and amplifying the frequency of transmitted signals, and an RF receiver for amplifying low noise and down-converting the frequency of received signals. However, this is only one example of the transceiver 1310, and the components of the transceiver 1310 are not limited to an RF transmitter and an RF receiver.

[0163] In addition, the transceiver 1310 may receive a signal through a wireless channel and output it to the processor 1330 , and transmit a signal output from the processor 1330 through a wireless channel.

[0164] The memory 1320 may store programs and data required for UE operation. In addition, the memory 1320 may store control information or data included in signals obtained by the UE. The memory 1320 may be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, a DVD, or a combination of storage media.

[0165] The processor 1330 may control a series of processes so that the UE operates as described above. For example, the transceiver 1310 may receive a data signal including a control signal transmitted by a base station or a network entity, and the processor 1330 may determine the result of receiving the control signal and the data signal transmitted by the base station or the network entity.

[0166] Figure 14 The structure of a network entity according to the embodiments disclosed herein is shown.

[0167] Reference Figure 14 , the network entity includes a transceiver (1410), a memory (1420), and a processor (1430). The transceiver (1410), the memory (1420), and the processor (1430) of the network entity can operate according to the communication method of the above-mentioned network entity. However, the components of the terminal are not limited thereto. For example, the network entity may include fewer or more components than the above-mentioned components. However, the components of the network entity are not limited thereto. For example, the network entity may include more or fewer components than the above-mentioned components. In addition, the processor (1430), the transceiver (1410), and the memory (1420) can be implemented as a single chip. In addition, the processor (1430) may include at least one processor.

[0168] The network entity includes at least one entity of the core network. For example, the network entity includes AMF, session management function (SMF), policy control function (PCF), network repository function (NRF), user plane function (UPF), network slice selection function (NSSF), authentication server function (AUSF), UDM and network exposure function (NEF), but the network entity is not limited thereto.

[0169] The transceiver (1410) is generally referred to as a network entity receiver and a network entity transmitter, and can transmit and receive signals to and from a base station or a UE. The signals transmitted to and received from the base station or the UE may include control information and data. In this regard, the transceiver (1410) may include an RF transmitter for up-converting and amplifying the frequency of a transmitted signal, and an RF receiver for amplifying low noise and down-converting the frequency of a received signal. However, this is only one example of the transceiver (1410), and the components of the transceiver (1410) are not limited to the RF transmitter and the RF receiver.

[0170] The transceiver (1410) may receive a signal through a wireless channel and output it to the processor (1430), and transmit a signal output from the processor (1430) through a wireless channel.

[0171] The memory (1420) can store programs and data required for the operation of the network entity. In addition, the memory (1420) can store control information or data included in the signal obtained by the network entity. The memory (1420) can be a storage medium such as ROM, RAM, hard disk, CD-ROM and DVD, or a combination of storage media.

[0172] The processor (1430) may control a series of processes so that the network entity operates as described above. For example, the transceiver (1410) may receive a data signal including a control signal, and the processor (1430) may determine a result of receiving the data signal.

[0173] The processors disclosed herein may include various processing circuits and / or multiple processors. For example, as used herein, including the claims, the term "processor" may include various processing circuits, including at least one processor, wherein one or more of the at least one processor may be configured, individually and / or collectively, in a distributed manner to perform the various functions described herein. As used herein, when "processor," "at least one processor," and "one or more processors" are described as being configured to perform multiple functions, these terms cover, for example, but not limited to, situations where one processor performs some of the described functions and another processor performs other described functions, as well as situations where a single processor may perform all of the described functions. In addition, the at least one processor may include, for example, a combination of processors that perform the various described / disclosed functions in a distributed manner. The at least one processor may execute program instructions to implement or perform the various functions.

[0174] In various embodiments, a method for handling lower layer triggered mobility (LTM) in a wireless network (1000) includes: a user equipment (UE) (100) receiving a radio resource control (RRC) reconfiguration from a network entity (200), the RRC reconfiguration including an LTM configuration having at least one of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration; upon successful completion of the RRC reconfiguration, the UE (100) sending an RRC reconfiguration complete to the network entity (200) based on the RRC reconfiguration; and when the UE (100) is measuring the same reference signal for an L3 measurement result and an LTM measurement, the UE (100) reusing one of: the L3 measurement result, and a portion of the L3 measurement result for the LTM measurement.

[0175] Preferably, when access stratum (AS) security has been activated, the network entity (200) provides an LTM configuration in RRC reconfiguration, the LTM configuration including at least one of an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration.

[0176] Preferably, when a signaling radio bearer 2 (SRB2) having at least one of a data radio bearer (DRB) is set and not suspended, or when one of a multicast radio bearer (MRB) and SRB2 is set and not suspended, the network entity (200) provides an LTM configuration including at least one of an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration in RRC reconfiguration.

[0177] Preferably, the network entity (200) provides LTM configuration for a secondary cell group (SCG) in New Radio Dual Connectivity (NR-DC) in RRC reconfiguration in SRB3.

[0178] Preferably, the reference signals correspond to the same serving cell or the same neighbor cell.

[0179] In various embodiments, a method for handling lower layer triggered mobility in a wireless network (1000) includes: receiving, by a UE (100), an RRCReconfiguration including information for releasing an LTM configuration; and releasing, by the UE (100), the LTM configuration based on the received RRCReconfiguration.

[0180] In various embodiments, a method for handling lower layer triggered mobility includes: receiving, by a first network entity, a Dual Active Protocol Stack (DAPS) handover command in the first network entity from a second network entity; sending, by the first network entity, the DAPS handover command to a UE (100); and releasing, by the first network entity, an LTM configuration before sending the DAPS handover command to the UE (100).

[0181] Preferably, the method further comprises: skipping LTM configuration by the second network entity until the DAPS handover is completed.

[0182] In various embodiments, a method for handling lower layer triggered mobility in a wireless network (1000) includes: sending, by a network entity (200), a radio resource control (RRC) reconfiguration to a user equipment (UE) (100), the RRC reconfiguration including an LTM configuration having at least one of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration; and receiving, by the network entity (200), an RRC reconfiguration complete from the UE (100) based on the RRC reconfiguration.

[0183] Preferably, when access stratum (AS) security has been activated, the network entity (200) provides an LTM configuration including at least one of an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration in an RRC reconfiguration.

[0184] Preferably, when a signaling radio bearer 2 (SRB2) having at least one of a data radio bearer (DRB) is set and not suspended, or when one of a multicast radio bearer (MRB) and SRB2 is set and not suspended, the network entity (200) provides an LTM configuration including at least one of an LTM candidate cell configuration, an LTM reference configuration, and an LTM measurement configuration in RRC reconfiguration.

[0185] Preferably, when the RRC reconfiguration is not sent through DLInformationTransferMRDC, the network entity (200) provides the LTM configuration for the SCG in NR-DC in the RRC reconfiguration included in SRB3.

[0186] In various embodiments, a UE (100) includes: a processor (110); a memory (130); and an LTM controller (140), the LTM controller being coupled to the processor (110) and the memory (130) and configured to: receive a radio resource control (RRC) reconfiguration from a network entity (200), the RRC reconfiguration including an LTM configuration having at least one of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration; upon successful completion of the RRC reconfiguration, send an RRC reconfiguration completion to the network entity (200) based on the RRC reconfiguration; and when the UE (100) is measuring the same reference signal for an L3 measurement result and an LTM measurement, reuse one of the following: the L3 measurement result, and a portion of the L3 measurement result for the LTM measurement.

[0187] In various embodiments, a UE (100) includes: a processor (110); a memory (130); and an LTM controller (140), the LTM controller being coupled to the processor (110) and the memory (130) and configured to: receive an RRC reconfiguration including information for releasing an LTM configuration; and release the LTM configuration based on the RRC reconfiguration.

[0188] In various embodiments, a network entity (200) includes: a processor (210); a memory (230); and an LTM controller (240), the LTM controller being coupled to the processor (210) and the memory (230) and configured to: receive a dual active protocol stack (DAPS) handover command in a first network entity from a second network entity; send the DAPS handover command to a UE (100); and release an LTM configuration before triggering the DAPS handover command to the UE (100).

[0189] In various embodiments, a network entity (200) includes: a processor (210); a memory (230); and an LTM controller (240), the LTM controller being coupled to the processor (210) and the memory (230) and configured to: send a radio resource control (RRC) reconfiguration to a user equipment (UE) (100), the RRC reconfiguration including an LTM configuration having at least one of an LTM candidate cell configuration, an LTM measurement configuration, and an LTM reference configuration; and receive an RRC reconfiguration completion from the UE (100) based on the RRC reconfiguration.

[0190] The embodiments disclosed herein may be implemented by at least one software program running on at least one hardware device and performing network management functions to control elements. These elements may be at least one of a hardware device or a combination of a hardware device and a software module.

[0191] The embodiments herein have been explained using 5G and associated modules (gNB, NR, UE); however, it will be clear to those skilled in the art that the embodiments herein can be extended to any network / technology (6G, etc.) and associated components (i.e., the gNB can be any network node, and the UE can be any technology / network, etc.).

[0192] The foregoing description of specific embodiments will fully reveal the general nature of the embodiments herein so that others can easily modify and / or adapt these specific embodiments to various applications by applying current knowledge without departing from the general concepts, and therefore, these adaptations and modifications should and are intended to be understood as being within the equivalent meaning and scope of the disclosed embodiments. It should be understood that the words or terms used herein are for description and not limitation. Therefore, although 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 modifications made within the spirit and scope of the embodiments described herein.

Claims

1. A method performed by a user equipment (UE) in wireless communication, the method comprising: receiving a radio resource control RRC reconfiguration message from a base station BS, the RRC reconfiguration message including information about a lower layer triggered mobility LTM configuration; performing L3 measurements on at least one cell; and An L1 measurement report including a result of the L3 measurement is sent to the BS.

2. The method according to claim 1, in, The information is configured to release the LTM configuration. The method further includes executing an LTM configuration release process.

3. The method according to claim 1, in, The information about the LTM configuration is received from the BS via signaling radio bearer 3 SRB3.

4. The method according to claim 1, in, The information about the LTM configuration is included in case access stratum AS security is activated and signaling radio bearer 2 SRB2 with data radio bearer DRB is set up and not suspended.

5. A user equipment (UE) in a wireless communication system, the UE comprising: transceiver; at least one processor coupled to the transceiver and configured to: receiving a radio resource control RRC reconfiguration message from a base station BS, the RRC reconfiguration message including information about a lower layer triggered mobility LTM configuration; performing L3 measurements on at least one cell; and An L1 measurement report including a result of the L3 measurement is sent to the BS.

6. The UE according to claim 5, in, The information is configured to release the LTM configuration. The method further includes executing an LTM configuration release process.

7. The UE according to claim 5, in, The information about the LTM configuration is received from the BS via signaling radio bearer 3 SRB3.

8. The UE according to claim 5, in, The information about the LTM configuration is included in case access stratum AS security is activated and signaling radio bearer 2 SRB2 with data radio bearer DRB is set up and not suspended.

9. A method performed by a base station (BS) in wireless communication, the method comprising: Sending a radio resource control (RRC) reconfiguration message to a user equipment (UE), wherein the RRC reconfiguration message includes information about a lower layer triggered mobility (LTM) configuration; as well as An L1 measurement report including a result of an L3 measurement is received from the UE.

10. The method according to claim 9, in, The information is arranged to release the LTM configuration.

11. The method according to claim 9, in, The information about the LTM configuration is sent to the UE via signaling radio bearer 3 SRB3.

12. The method according to claim 9, in, The information about the LTM configuration is included in case access stratum AS security is activated and signaling radio bearer 2 SRB2 with data radio bearer DRB is set up and not suspended.

13. A base station (BS) in a wireless communication system, the BS comprising: transceiver; at least one processor coupled to the transceiver and configured to: sending a radio resource control (RRC) reconfiguration message to a user equipment (UE), the RRC reconfiguration message including information about a lower layer triggered mobility (LTM) configuration; and An L1 measurement report including a result of an L3 measurement is received from the UE.

14. The BS according to claim 13, in, The information is arranged to release the LTM configuration.

15. The BS according to claim 13, in, The information about the LTM configuration is sent to the UE via signaling radio bearer 3 SRB3, and Wherein, the information about the LTM configuration is included when access layer AS security is activated and a signaling radio bearer 2 SRB2 having a data radio bearer DRB is set and not suspended.

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