Method and apparatus for managing conditional ltm

Abstract

Embodiments herein disclose methods and systems for configuring lower layer triggered mobility and conditional lower layer triggered mobility by the gNB (106) and handling the configurations by the UE. Embodiments herein disclose methods and systems for executing conditional LTM. In an embodiment, a method can be used for managing conditional LTM by the UE (200). The method includes receiving a conditional LTM configuration for executing an LTM cell switch. The conditional LTM configuration comprises one or more conditions. Further, the method includes measuring one or more reference signals of at least one candidate cell and at least one serving cell. Further, the method includes executing the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

Description

METHOD AND APPARATUS FOR MANAGING CONDITIONAL LTM

[0001] Embodiments disclosed herein relate to wireless communication networks, and more particularly to managing mobility and conditional mobility in wireless communication networks.

[0002] In the initial stage of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced mobile broadband (eMBB), ultra reliable & low latency communications (URLLC), and massive machine-type communications (mMTC), there has been ongoing standardization regarding beamforming and massive multiple-input multiple-output (MIMO) for alleviating radio-wave path loss and increasing radio-wave transmission distances in mmWave, numerology (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of bandwidth part (BWP), new channel coding methods, such as a low density parity check (LDPC) code for large-capacity data transmission and a polar code for highly reliable transmission of control information, layer 2 (L2) pre-processing, and network slicing for providing a dedicated network customized to a specific service.

[0003] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies, such as vehicle-to-everything (V2X) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, new radio unlicensed (NR-U) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, new radio (NR) user equipment (UE) power saving, non-terrestrial network (NTN) which is UE-satellite direct communication for securing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0004] Moreover, there has been ongoing standardization in wireless interface architecture / protocol fields regarding technologies, such as industrial Internet of things (IIoT) for supporting new services through interworking and convergence with other industries, integrated access and backhaul (IAB) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and dual active protocol stack (DAPS) handover, and two-step random access for simplifying random access procedures (2-step random access channel (RACH) for NR). There also has been ongoing standardization in system architecture / service fields regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining network functions virtualization (NFV) and software-defined networking (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE positions.

[0005] If such 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with extended reality (XR) for efficiently supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), or the like, 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, and drone communication.

[0006] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for securing coverage in terahertz bands of 6G mobile communication technologies, full dimensional MIMO (FD-MIMO), multi-antenna transmission technologies, such as array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using orbital angular momentum (OAM), and reconfigurable intelligent surface (RIS), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and artificial intelligence (AI) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0007] The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure.

[0008] The evolution of mobile communication technologies has been marked by the gradual phasing out of older standards in favor of more advanced and efficient systems. The shutdown of 2G and 3G networks is a part of this global trend, as operators and countries prepare to adopt newer technologies such as 5G and even anticipate the future deployment of 6G. The Global Mobile Suppliers Association (GSA) has identified numerous operators worldwide that have either announced or completed the shutdown of their 2G and / or 3G networks. Despite being introduced in 1991 and serving as a foundation for mobile communication for decades, 2G is now considered outdated, with some providers beginning to close down their networks as early as 2017. However, there remains a divergence in strategy, as certain carriers continue to operate 2G networks, citing reasons such as coverage and compatibility with existing devices.

[0009] The transition away from 2G and 3G networks presents several challenges, particularly in terms of security and connectivity. One significant concern is the vulnerability of devices to fake base station attacks, which exploit the weaker encryption and lack of authentication inherent in 2G and 3G networks. These attacks can intercept calls and messages, leading to privacy breaches and potential fraud. The absence of base station authentication in 2G networks allows attackers to impersonate legitimate base stations, making it possible for them to conduct bidding down attacks. Such attacks can redirect a device from a secure 4G or 5G network to a less secure 2G or 3G network, exposing sensitive information like the International Mobile Subscriber Identity (IMSI) and enabling tracking of the user equipment (UE).

[0010] Moreover, users are often provided with the option to manually disable 2G connectivity on their devices to mitigate these security risks. However, this solution is not without drawbacks. Disabling 2G can render a device out of service in regions where 2G is the only available network for voice calls or where roaming requires 2G connectivity. This limitation highlights the need for a more sophisticated mechanism that allows the network to determine the supported wireless generation and guide the UE accordingly, based on factors such as location, radio conditions, and device capabilities.

[0011] In addition to security concerns, the prioritization of available networks is another area that requires attention. When powered on, a UE performs PLMN selection, ideally choosing its home public land mobile network (HPLMN). However, the process involves various factors, including operator and user-controlled PLMN selectors, which can influence the prioritization of one network over another. The automatic selection algorithm typically favors the HPLMN or equivalent networks, but challenges arise when the UE encounters 2G / 3G networks, which may still be prioritized in certain scenarios.

[0012] Given these challenges, there is a pressing need for solutions that address the security vulnerabilities associated with 2G and 3G networks, ensure seamless connectivity in areas where these networks are still in use, and optimize network selection processes to prioritize more secure and efficient technologies. Such solutions would not only enhance the security and reliability of mobile communications but also provide a more robust framework for the ongoing transition to newer generations of wireless technology

[0013] The principal object of embodiments herein is to disclose methods and systems for configuring lower layer triggered mobility and conditional lower layer triggered mobility by the gNB and handling the configurations by the UE.

[0014] Another object of embodiments herein is to disclose methods and systems for executing conditional LTM.

[0015] Another object of embodiments herein is to receive a conditional LTM configuration for executing an LTM cell switch, wherein the conditional LTM configuration comprises one or more conditions.

[0016] Another object of embodiments herein is to measure one or more reference signals of at least one candidate cell and at least one serving cell.

[0017] Another object of embodiments herein is to execute the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

[0018] Another object of embodiments herein is to disclose methods and systems for UE capability reporting for conditional LTM.

[0019] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

[0020] Accordingly, the embodiments herein provide a method for managing conditional LTM. The method includes receiving, by a UE, a conditional LTM configuration for executing an LTM cell switch. The conditional LTM configuration comprises one or more conditions. Further, the method includes measuring, by the UE, one or more reference signals of at least one candidate cell and at least one serving cell. Further, the method includes executing, by the UE, the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

[0021] Accordingly, the embodiments herein provide a UE includes a processor and a memory. The processor is configured to receive a conditional LTM configuration for executing an LTM cell switch, where the conditional LTM configuration comprises one or more conditions. Further, the processor is configure to measure one or more reference signals of at least one candidate cell and at least one serving cell. Further, the processor is configured to execute the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

[0022] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating at least one embodiment and numerous specific details thereof, are given by way of illustration and not of limitation. 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.

[0023] The present invention provides methods and systems for configuring lower layer triggered mobility and conditional lower layer triggered mobility by the gNB and handling the configurations by the UE.

[0024] The present invention provides methods and systems for executing conditional LTM.

[0025] The present invention provides a method to receive a conditional LTM configuration for executing an LTM cell switch, wherein the conditional LTM configuration comprises one or more conditions.

[0026] The present invention provides a method to measure one or more reference signals of at least one candidate cell and at least one serving cell.

[0027] The present invention provides a method to execute the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

[0028] The present invention provides methods and systems for UE capability reporting for conditional LTM.

[0029] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

[0030] Embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the following illustratory drawings. Embodiments herein are illustrated by way of examples in the accompanying drawings, and in which:

[0031] FIG. 1 depicts the NG-RAN architecture (as in TS 38.401), according to existing arts;

[0032] FIG. 2 depicts the signaling procedure for LTM, according to existing arts;

[0033] FIG. 3 shows various hardware components of a wireless network for managing conditional LTM, according to embodiments as disclosed herein;

[0034] FIG. 4a shows various hardware components of a UE, according to embodiments as disclosed herein;

[0035] FIG. 4b shows various hardware components of the network node, according to embodiments as disclosed herein;

[0036] FIG. 5 is a flow chart illustrating a method for managing conditional Lower-layer　Triggered　Mobility (LTM), according to embodiments as disclosed herein;

[0037] FIG. 6 depicts the process of Conditional LTM configuration, according to embodiments as disclosed herein; and

[0038] FIG. 7 depicts the process of releasing conditional LTM configuration, according to embodiments as disclosed herein.

[0039] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0040] The words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.,", "i.e.," are merely used herein to mean "serving as an example, instance, or illustration. Any embodiment or implementation of the present subject matter described herein using the words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.," , "i.e.," is not necessarily to be construed as preferred or advantageous over other embodiments.

[0041] Embodiments herein may be described and illustrated in terms of blocks which carry out a described function or functions.　These blocks, which may be referred to herein as managers, units, modules, hardware components or the like, 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, hardwired circuits and the like, and may optionally be driven by a firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like.　The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block.　Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure.　Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

[0042] It should be noted that elements in the drawings are illustrated for the purposes of this description and ease of understanding and may not have necessarily been drawn to scale. For example, the flowcharts / sequence diagrams illustrate the method in terms of the steps required for understanding of aspects of the embodiments as disclosed herein. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Furthermore, in terms of the system, one or more components / modules which comprise the system may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0043] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any modifications, equivalents, and substitutes in addition to those which are particularly set out in the accompanying drawings and the corresponding description. Usage of words such as first, second, third etc., to describe components / elements / steps is for the purposes of this description and should not be construed as sequential ordering / placement / occurrence unless specified otherwise.

[0044] From TS 38.401, FIG. 1 depicts the NG-RAN architecture. The NG-RAN (104) comprises a set of gNBs (106a, 106b) (hereafter the label for gNB is 106) connected to a 5GC (102) through the NG interface. The gNBs can be interconnected through the Xn interface. A gNB may consist of a gNB-CU (108a) and one or more gNB-DU(s) (110a, 110b). The gNB-CU (108a) and the gNB-DU is connected via F1 interface.

[0045] Mobility in wireless networks:In wireless technologies like 5G NR, devices can move across different cells. Mobility is performed using a procedure called cell reselection in RRC_IDLE mode. Till NR R17, mobility is performed using a procedure called handover in RRC_CONNECTED mode. Network controlled mobility applies to UEs in RRC_CONNECTED. It requires explicit RRC signalling to be triggered by the gNB (106) in NR. Handover in NR usually consists of three steps: handover preparation, handover execution and handover completion. The gNB (106) may configure the UE to report measurements and based on the reported measurements or based on its own understanding of the network topology, the gNB (106) will send RRC Reconfiguration message to handover the UE to another cell called target cell from the source cell. the UE accesses the target cell and sends RRC Reconfiguration complete message. In an alternative way (introduced in 3gpp NR release 16), the gNB (106) may configure the UE with the execution conditions for triggering handover. Once the execution conditions are satisfied, the UE may move to target cell and sends the RRC Reconfiguration complete. 3gpp also introduced a new handover called DAPS handover in release 16. In all these methods, the UE performs handover by sending layer 3 (RRC) messages which causes considerable signalling overhead and latency issues. The handover, and conditional handover (CHO) are referred to herein as layer 3 mobility. In case of dual connectivity, the UE may perform PSCellChange or Conditional PSCellChange. In the context of dual connectivity, PSCellChange or Conditional PSCellChange are also referred to herein as layer 3 mobility; i.e., Handover, Conditional Handover, PSCellChange,Conditional PSCellChange etc. refers to L3 mobility. PSCellChange or Conditional PSCellChange are also referred to herein as SCG layer 3 mobility and the handover and CHO are also referred to herein as MCG layer 3 mobility in the context of dual connectivity.

[0046] 3gpp release 18 is considering Lower Layers (L1 / L2 layers) Triggered Mobility, also known as LTM to solve the problem related to latency, signalling overhead etc. associated with layer 3 mobility. As per 3gpp, the goal of LTM is to enable a serving cell change via L1 / L2 signalling, in order to reduce the latency, overhead and interruption time. The network node (gNB) (106) may configure the UE with multiple candidate cells to allow fast application of configurations for candidate cells. The network may further send MAC CE or L1 signalling to dynamically switch the UE from a source cell to one of the configured candidate cells. Further, LTM can be triggered based on L1 measurements rather than L3 measurements.

[0047] 3gpp proposes to perform LTM, without reset of lower layers like MAC to avoid data loss and to reduce the additional delay of data recovery wherever it is possible.

[0048] The gNB CU (108) may provide LTMCandidateConfiguration, i.e. configure LTM candidate cells through one RRCReconfiguration message for a candidate target cell. The gNB (106) may further release or modify the candidate configurations. A UE may store the LTM configuration of other candidate cells even after moving to a candidate cell through LTM. The gNB CU (108) also may provide the UE with configuration for performing LTM measurements for different candidate frequencies and candidate cells and reporting based on the performed LTM measurements. The gNB (106) may further release or modify the candidate configurations. The UE may store the LTM configuration of other candidate cells even after moving to a candidate cell through LTM. The gNB (106) also may provide the UE with configuration for performing LTM measurements for different candidate frequencies and candidate cells and reporting based on the performed LTM measurements. 3gpp supports subsequent LTM, i.e., after one LTM candidate cell becomes a source cell due to LTM, the UE may store LTM candidate configuration and continue to report LTM measurements (L1 measurements for LTM) and the new serving cell may send LTM cell switch command to the UE and the UE performs LTM. Such an LTM is called subsequent LTM.

[0049] The UE performs the L1 measurements on the source cell and candidate cell and report L1 measurements through CSI reports to the gNB DU of the source cell. The gNB DU (110) may send a MAC CE (for e.g. LTM MAC CE or cell switch MAC CE) asking the UE to switch to another cell which is an LTM candidate cell. The UE may perform random access during LTM cell switch, or the cell switch may be RACH less. CellSwitch may be guarded by a timer (referred as T3xx in this invention)

[0050] The UE may be requested to perform random access on a candidate cell before the cell switch, so that the network can calculate the timing advance before the cell switch and inform the UE either through a random access response or within the MAC CE which is send for the cell switch. The gNB (106) may configure the UE to perform random access towards one or more LTM candidate cells for receiving the timing advance (TA) before the cell switch is performed (known as Early TA or Early Sync TA or TA for Early Sync). Random access performed on LTM candidate cells for the timing advance reception is known as Random access for early TA. The gNB (106) sends a PDCCH order to initiate RACH for TA measurement for candidate cells. The UE receives PDCCH order from the serving cell. Upon reception of this PDCCH order, the UE initiates RACH for TA measurement for candidate cells on the one or more candidate cell. The UE sends RACH preamble to the candidate cells and receives the Timing Advance (TA) value from the candidate cell. The TA for candidate cells may be received from the source cell also. Normally, the TA will be received in the random access response, but it may be also received through a MAC CE. If source DU indicates the UE to retransmit the RACH for early TA, the UE retransmits the same. The gNB (106) may also send PDCCH order to retransmit RACH for TA measurement (also known as RACH for early sync).

[0051] A detailed description of the LTM from 3gpp documents is give below.

[0052] The LTM is a procedure in which the gNB (106) receives L1 measurement report(s) from a UE, and on their basis the gNB (106) changes UE's serving cell by a cell switch command signaled via a MAC CE. The cell switch command indicates an LTM candidate cell configuration that the gNB (106) previously prepared and provided to the UE through RRC signalling. Then the UE switches to the target cell according to the cell switch command. The LTM procedure can be used to reduce the mobility latency as described.

[0053] Network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition is triggered by PDCCH order [or through UE-based TA measurement].

[0054] The network indicates in the cell switch command whether the UE shall access the target cell with a RA procedure if a TA value is not provided or with PUSCH transmission using the indicated TA value. For RACH-less LTM, the UE either monitors PDCCH for dynamic scheduling from the target cell upon LTM cell switch, or the UE selects the configured grant occasion associated with the beam indicated in the cell switch command.

[0055] The following principles apply to LTM:

[0056] a) The UE doesn't update its security key in LTM.

[0057] b) Subsequent LTM is supported.

[0058] LTM supports both intra-gNB-DU and intra-gNB-CU inter-gNB-DU mobility. LTM also supports inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. The following scenarios are supported:

[0059] a) PCell change in non-CA scenario,

[0060] b) PCell change in CA scenario,

[0061] c) Dual connectivity scenario, at least for the PSCell change without MN involvement case, i.e. intra-SN PSCell change.

[0062] A supervision timer can be used to detect failure of LTM cell switch procedure, wherein LTM procedure fails if the LTM supervision timer expires, upon which the UE initiates RRC connection re-establishment procedure.

[0063] While the UE has stored LTM candidate cell configurations the UE can also execute any L3 handover command sent by the network. It is up to the network to avoid any issue due to a collision between LTM execution and L3 handover execution, e.g. avoiding sending LTM cell switch command and L3 handover command simultaneously.

[0064] Cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

[0065] The signaling procedure for LTM is shown in FIG. 2. Subsequent LTM is done by repeating the early synchronization, LTM execution, and LTM completion steps without releasing other LTM candidate cell configurations after each LTM completion. In step 1, the UE sends a MeasurementReport message to the gNB (106). The gNB (106) decides to configure LTM and initiates candidate cell(s) preparation. In step 2, the gNB (106) transmits an RRCReconfiguration message to the UE including the LTM candidate cell configurations of one or multiple candidate cells. In step 3, the UE stores the LTM candidate cell configurations and transmits an RRCReconfigurationComplete message to the gNB (106). In step 4a, the UE [may] perform DL synchronization with candidate cell(s) before receiving the cell switch command. In step 4b, the UE [may] perform early TA acquisition with candidate cell(s) requested by the network before receiving the cell switch command. This is done via CFRA triggered by a PDCCH order from the source cell, following which the UE sends preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the UE doesn't receive RAR for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE doesn't maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity. In step 5, the UE performs L1 measurements on the configured candidate cell(s), and transmits lower-layer measurement reports to the gNB (106). The L1 measurement should be performed as long as apply the RRC reconfiguration in step 2. In step 6, the gNB (106) decides to execute cell switch to a target cell, and transmits a MAC CE triggering cell switch by including the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by candidate configuration index. In step 7, the UE performs the random access procedure towards the target cell, if UE does not have valid TA of the target cell. In step 8, the UE completes the LTM cell switch procedure [by sending RRCReconfigurationComplete message to target cell]. If the UE has performed a RA procedure (as in step 7), the UE considers that LTM execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers that LTM execution is successfully completed when the UE determines that the network has successfully received its first UL data. The steps 4-8 can be performed multiple times for subsequent LTM cell switch using the LTM candidate cell configuration(s) (as provided in step 2).

[0066] For the purpose herein, 3gpp specifications such as TS38.300, TS38.331, TS 38.321 V17.4.0 can be considered as relevant background.

[0067] A set of known specification extracts for the LTM with respect to the discussions in 3gpp for TS 38.331 are given below:

[0068] Complete LTM Candidate Cell Configuration: A configuration that contains all the necessary fields needed to perform an LTM cell switch procedure. This configuration can be an LTM candidate cell configuration itself or be generated by applying an LTM candidate cell configuration on top of an LTM reference configuration.

[0069] LTM Candidate Cell Configuration:A configuration associated with an LTM candidate cell. An LTM candidate cell configuration can be a complete LTM candidate cell configuration or a delta (difference) configuration with respect to an LTM reference configuration.

[0070] LTM Reference Configuration:A configuration provided by the network to the UE that is common to all the configured LTM candidate cells. It is used by the UE to generate a complete LTM candidate cell configuration (i.e., by applying an LTM candidate cell configuration on top of an LTM reference configuration).

[0071] 5.3.5.3Reception of an RRCReconfiguration by the UE:The UE shall perform the following actions upon reception of the RRCReconfiguration, upon execution of the conditional reconfiguration (CHO, CPA or CPC), or upon execution of an LTM cell switch:

[0072] 1> if the RRCReconfiguration message includes the ltm-Config:

[0073] 2> if the ltm-Config is set as setup:

[0074] 3> perform the LTM configuration procedure as specified in 5.3.5.x;

[0075] 2> else:

[0076] 3> perform LTM configuration release as specified in clause 5.3.5.x.7;

[0077] 1> if reconfigurationWithSync was included in spCellConfig of an MCG or SCG due to an LTM cell switch without performing a Random Access procedure and when MAC indicates the successful reception of a PDCCH transmission addressed to C-RNTI:

[0078] 2> stop timer T304 for that cell group if running;

[0079] 2> if sl-PathSwitchConfig was included in reconfigurationWithSync:

[0080] 3> stop timer T420;

[0081] 3> release all radio resources, including release of the RLC entities and the MAC configuration at the source side;

[0082] 3> reset MAC used in the source cell;

[0083] NOTE 2b: PDCP and SDAP configured by the source prior to the path switch that are reconfigured and re-used by target when delta signalling is used, are not released as part of this procedure.

[0084] 2> stop timer T310 for source SpCell if running;

[0085] 2> apply the parts of the CSI reporting configuration, the scheduling request configuration and the sounding RS configuration that do not require the UE to know the SFN of the respective target SpCell, if any;

[0086] 2> apply the parts of the measurement and the radio resource configuration that require the UE to know the SFN of the respective target SpCell (e.g. measurement gaps, periodic CQI reporting, scheduling request configuration, sounding RS configuration), if any, upon acquiring the SFN of that target SpCell;

[0087] <various other steps for LTM >

[0088] 5.3.5.xLTM configuration and execution

[0089] 5.3.5.x.1 General:The network configures the UE with one or more LTM candidate cell configurations within the LTM-Config IE.

[0090] In NR-DC, the UE may receive two independent ltm-Config:

[0091] a) an ltm-Config associated with the MCG that is included within an RRCReconfiguration message received via SRB1; and / or

[0092] b) an ltm-Config associated with the SCG that is included within an RRCReconfiguration message either received via SRB3, or, alternatively, embedded in a RRCReconfiguration message received via SRB1.

[0093] In this case:

[0094] a) the UE maintains two independent VarLTM-Config, one associated with each ltm-Config;

[0095] b) the UE maintains two independent VarLTM-UE-Config, one associated with each ltm-Config;

[0096] c) the UE independently performs all the procedures in clause 5.3.5.x for each ltm-Config and the associated VarLTM-Config and VarLTM-UE-Config, unless explicitly stated otherwise.

[0097] The UE shall perform the following actions based on the received LTM-Config IE:

[0098] 1> if ltm-ReferenceConfiguration is present within VarLTM-Config and LTM-Config includes ltm-ReferenceConfiguration:

[0099] 2> replace ltm-ReferenceConfiguration within VarLTM-Config with the received ltm-ReferenceConfiguration within the LTM-Config IE.

[0100] 2> for each ltm-CandidateId value in VarLTM-Config:

[0101] 3> perform the actions to generate a complete LTM configuration as specified in 5.3.5.x.4;

[0102] 1> else:

[0103] 2> store the received ltm-ReferenceConfiguration in VarLTM-Config;

[0104] 1> if the LTM-Config includes ltm-ServingCellNoResetID:

[0105] 2> consider the received ltm-ServingCellNoResetID value as the ltm-ServingCellNoResetID value associated with current serving cell for this cell group;

[0106] 1> if the LTM-Config includes the ltm-CandidateToAddModList:

[0107] 2> perform the LTM candidate cell addition or reconfiguration as specified in 5.3.5.x.3;

[0108] 1> else if the LTM-Config includes the ltm-CandidateToReleaseList:

[0109] 2> perform the LTM candidate cell release as specified in 5.3.5.x.2;

[0110] 5.3.5.x.2 LTM candidate cell release

[0111] The UE shall:

[0112] 1> for each ltm-CandidateId value in the ltm-CandidateToReleaseList:

[0113] 2> if the current VarLTM-Config includes an LTM-Candidate associated with the given ltm-CandidateId value:

[0114] 3> remove the entry related to LTM-Candidate from VarLTM-Config;

[0115] 2> if the current VarLTM-UE-Config includes a UE-LTM-Candidate with the given ltm-CandidateId value:

[0116] 3> remove the entry related to UE-LTM-Candidate from VarLTM-UE-Config.

[0117] 5.3.5.x.3 LTM candidate cell addition / modification:

[0118] The UE shall:

[0119] 1> for each ltm-CandidateId value in the ltm-CandidateToAddModList:

[0120] 2> if the current VarLTM-Config includes an LTM-Candidate with the given ltm-CandidateId value:

[0121] 3> replace the LTM-Candidate within VarLTM-Config in accordance with the received LTM-Candidate;

[0122] 2> else:

[0123] 3> add the received LTM-Candidate to VarLTM-Config.

[0124] 2> perform the actions to generate a complete LTM configuration as specified in 5.3.5.x.4;

[0125] NOTE X: It is up to the UE implementation to postpone the generation of a complete LTM configuration as specified in 5.3.5.x.4 until the executing of an LTM cell switch.

[0126] 5.3.5.x.4Generation of UE LTM configuration:The purpose of this procedure is for the UE to generate a complete LTM candidate cell configuration to be stored upon it is generated and applied only when an indication of an LTM cell switch is received by lower layers. During the generation of a complete LTM candidate cell configuration, the UE shall not modify its current configuration.

[0127] The UE shall:

[0128] 1> if there is no entry in ue-ltm-ConfigCandidateList within VarLTM-UE-Config with ltm-CandidateId value set to the value of ltm-CandidateId included in the LTM-Candidate:

[0129] 2> create an entry in ue-ltm-ConfigCandidateList within VarLTM-UE-Config with value ltm-CandidateId;

[0130] 2> set to the value of ltm-CandidateId in that entry to the value included in the LTM-Candidate;

[0131] 1> in the entry of ue-ltm-ConfigCandidateList within VarLTM-UE-Config with ltm-CandidateId set to the value of ltm-CandidateId value included in the LTM-Candidate:

[0132] 2> if the LTM-Candidate includes ltm-ConfigComplete;

[0133] 3> if ue-LTM-config is present within VarLTM-UE-Config:

[0134] 4> replace ue-LTM-Config with the ltm-CandidateConfig included in the LTM-Config ;

[0135] 3> else:

[0136] 4> store in ue-LTM-Config the ltm-CandidateConfig included in the LTM-Config;

[0137] 2> else:

[0138] 3> generate a complete LTM candidate cell configuration by applying ltm-CandidateConfig on top of ltm-referenceConfiguration, according to clause 5.3.5.x.5.3> ue-LTM-config is present within VarLTM-UE-Config :

[0139] 4> replace replace ue-LTM-Config with the generated complete LTM candidate cell configuration;

[0140] 3> else:

[0141] 4> store in ue-LTM-Config the generated complete LTM candidate cell configuration.

[0142] 5.3.5.x.6 LTM cell switch execution:Upon the indication by lower layers that an LTM cell switch procedure is triggered, or upon performing LTM cell switch upon to cell selection performed while timer T311 was running, as specified in 5.3.7.3, the UE shall:

[0143] 1> release / clear all current dedicated radio configuration related to cell group to which the LTM cell switch procedure is triggered except for the following:

[0144] 2> if the LTM cell switch is triggered on the MCG:

[0145] - the MCG C-RNTI;

[0146] - the AS security configurations associated with the master key;

[0147] 2> else, if the LTM cell switch is triggered on the SCG:

[0148] - the AS security configurations associated with the secondary key;

[0149] - the SRB1 / SRB2 configurations and DRB configurations as configured by radioBearerConfig or radioBearerConfig2;

[0150] - the RLC entity configuration, which include one or more RLC-BearerConfig IEs;

[0151] - the UE variables VarLTM-Config and VarLTM-UE-Config.

[0152] NOTE X: Upon an LTM cell switch, the UE shall release the radio bearer(s) that are part of the current UE's configuration but not part of the LTM candidate cell configuration indicated by lower layers.

[0153] 1> release / clear all current common radio configuration related to cell group to which the LTM cell switch procedure is triggered;

[0154] 1> use the default values specified in 9.2.3 for timers T310, T311 and constants N310, N311 related to cell group to which the LTM cell switch procedure is triggered;

[0155] 1> apply the default L1 parameter values as specified in corresponding physical layer specifications;

[0156] 1> if the value of field ltm-NoResetID contained within the LTM-Candidate IE related to the LTM candidate cell configuration identity as received by lower layers is equal to the value of ltm-ServingCellNoResetID within VarLTM-ServingCellNoResetID:

[0157] 2> continue using the current RLC entity in the LTM candidate cell configuration indicated by lower layers;

[0158] 2> replace the value of ltm-ServingCellNoResetID in VarLTM-ServingCellNoResetID with the value received within ltm-NoResetID;

[0159] 1> else:

[0160] 2> for each RLC-BearerConfig within rlc-BearerToAddModList that is part of current UE configuration:

[0161] 3> re-establish the RLC entity as specified in TS 38.322 [4];

[0162] 2> for each drb-Identity value included in the drb-ToAddModList that is part of the current UE configuration:

[0163] 3> trigger the PDCP entity of this DRB to perform data recovery as specified in TS 38.323 [5];

[0164] 2> replace the value of ltm-ServingCellNoResetID in VarLTM-ServingCellNoResetID with the value received within ltm-NoResetID;

[0165] 1> continue using the current PDCP entity in the LTM candidate cell configuration indicated by lower layers;1> if the LTM cell switch is triggered by an indication from lower layers:

[0166] 2> apply the LTM configuration in ue-LTM-Config within VarLTM-UE-Config related to the LTM candidate cell configuration identity as received from lower layers according to clause 5.3.5.3;

[0167] 1> else (LTM cell switch triggered upon cell selection performed while timer T311 was running):

[0168] 2> apply the LTM configuration in ue-LTM-Config within VarLTM-UE-Config related to the LTM candidate cell configuration identity selected while timer T311 was running according to clause 5.3.5.3;

[0169] 2> perform LTM configuration release as specified in clause 5.3.5.x.7.

[0170] 1> consider the LTM candidate cell indicated by lower layers to be the serving cell;

[0171] 5.3.5.x.7 LTM configuration release:The UE shall:

[0172] 1> remove all entries within VarLTM-UE-Config for the cell group for which the LTM configuration release is triggered;

[0173] 1> remove all entries within VarLTM-Config for the cell group for which the LTM configuration release is triggered;

[0174] 1> remove ltm-Config for the cell group for which the LTM configuration release is triggered;

[0175] 1> remove from current UE configuration all entries of ltm-CSI-ReportConfigToAddModList for all serving cell related to the cell group for which the LTM configuration release is triggered.

[0176] While LTM is helpful for reducing the latency to near zero level, it may not be very robust. For instance, LTM depends on the UE reporting measurements and the network sending LTM cell switch command to trigger the mobility. Since the UE mobility occurs many a times while the UE is in low coverage, it is highly likely that the LTM cell switch command will not reach the UE. Thus there is a need to have a UE based LTM, which is not currently available.

[0177] Hence, there is a need in the art for solutions which will overcome the above mentioned drawback(s), among others.

[0178] The embodiments herein achieve methods and systems for configuring lower layer triggered mobility and conditional lower layer triggered mobility by the gNB and handling the configurations by the UE. The conditional LTM allows the UE to execute the LTM without explicitly reporting the measurements to the network node or receiving the LTM cell switch command. This increases the reliability of mobility, by reducing the failures due to the unsuccessful transmission of measurements or unsuccessful reception of LTM cell switch command. This also saves signaling since the UL (uplink) measurements for LTM can be avoided.

[0179] Accordingly, the embodiments herein provide a method for managing conditional LTM. The method includes receiving, by a UE, a conditional LTM configuration for executing an LTM cell switch. The conditional LTM configuration comprises one or more conditions. Further, the method includes measuring, by the UE, one or more reference signals of at least one candidate cell and at least one serving cell. Further, the method includes executing, by the UE, the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

[0180] In an embodiment, the conditional LTM configuration includes LTM candidate configuration for the candidate LTM cell and the thresholds. Once the thresholds are met, the UE executes LTM cell switch. In an embodiment, the UE informs whether the UE is capable of performing conditional LTM to the network node and the network node configures the UE based on the received capability In an embodiment, the UE releases the configuration for conditional LTM during RRC Reestablishment and transition to RRC_INACTIVE. In an embodiment, the network node handles the conditional LTM configuration when the DAPS is configured.

[0181] The proposed method reduces the signalling overhead of providing as the configuration can be stored and applied. The conditional LTM provides additional latency gain, by avoiding the delay for the reception of LTM cell switch from the network node.

[0182] Referring now to the drawings, and more particularly to FIGS. 3 through 7, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0183] FIG. 3 shows various hardware components of a wireless network (1000) for managing conditional LTM, according to embodiments as disclosed herein. The wireless network (1000) includes a UE (200) and a network node (106). The UE (200) can be, for example, but not limited to a laptop, a desktop computer, a notebook, a Device-to-Device (D2D) device, a vehicle to everything (V2X) device, a smartphone, a foldable phone, a smart TV, a tablet, a server, an IoT device, an Augmented Reality (AR) device, a Mixed Reality (MR) device, a Virtual Reality (VR) device, an immersive device, an XR device, a metaverse device or the like.

[0184] In an embodiment herein, the network node (such as a gNB (106)) configures the UE (200) with conditional LTM configuration. In an embodiment herein, conditional LTM configuration includes LTM candidate configuration for a candidate cell. In an embodiment herein, conditional LTM configuration include LTM configuration.

[0185] In an embodiment herein, conditional LTM configuration includes thresholds for LTM measurements (such as RSRP, RSRQ, SINR). In an embodiment herein, once the thresholds are met (measurements greater than threshold, measurements equal to threshold etc.), the UE (200) executes LTM cell switch. In an embodiment herein, conditional LTM configuration includes a timer and if the thresholds are met for the duration of timer, the UE (200) executes LTM cell switch. The measurements can be layer 3 measurements or layer 1 measurements. The condition includes the measurements for candidate cells and serving cells.

[0186] Capability handling:

[0187] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing conditional LTM. It may be performed as a per-UE capability without any FRx / xDD differentiation. In an embodiment herein, a UE supporting conditional LTM supports both MCG LTM and SCG LTM. In an embodiment herein, the UE (200) supporting conditional LTM supports either or both of MCG LTM or SCG LTM. The UE (200) informing the network node (106) that it support conditional LTM will also inform the network node (106) that it supports at least one MCG LTM and SCG LTM. The network node (106) such as 5G gNB identifies the LTM supported by the UE (200) is MCG LTM or SCG LTM or both based on other capability indications. If the UE (200) supports conditional LTM and MCG LTM, UE supports conditional LTM in MCG.

[0188] If the UE (200) supports conditional LTM and SCG LTM, UE supports conditional LTM for SCG.

[0189] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing conditional LTM for MCG. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting conditional LTM for MCG supports LTM for MCG, i.e. it would inform the gNB (106) that it supports LTM for MCG. The embodiment allows finer granularity for the implementation of MCG LTM in the UE(200), i.e. this allows the UE (200) to support MCG LTM and not SCG LTM and vice versa.

[0190] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing conditional LTM for SCG. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting conditional LTM for SCG supports LTM for SCG, i.e. it would inform the gNB (106) that it supports LTM for SCG. The embodiment allows finer granularity for the implementation of SCG LTM in the UE (200), i.e. this allows the UE (200) to support MCG LTM and not SCG LTM and vice versa.

[0191] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing Inter-CU conditional LTM. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting Inter-CU conditional LTM supports Inter-CU LTM, i.e. it would inform the gNB (106) that it supports Inter-CU LTM.

[0192] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing Inter-CU conditional LTM for MCG. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting Inter-CU conditional LTM for MCG supports Inter-CU LTM for MCG, i.e. it would inform the gNB (106) that it supports Inter-CU LTM for MCG.

[0193] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing Inter-CU conditional LTM for SCG. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting Inter-CU conditional LTM for SCG supports Inter-CU LTM for SCG, i.e. it would inform the gNB (106) that it supports Inter-CU LTM for SCG.

[0194] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing Inter-CU conditional LTM. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting Inter-CU conditional LTM supports Inter-CU LTM, i.e. it would inform the gNB (106) that it supports Inter-CU LTM.

[0195] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing IntrA-CU conditional LTM for MCG. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting Intra-CU conditional LTM for MCG supports Intra-CU LTM for MCG, i.e. it would inform the gNB (106) that it supports Intra-CU LTM for MCG.

[0196] In an embodiment herein, the UE (200) informs the network node (106) whether it is capable of performing Intra-CU conditional LTM for SCG. It may be performed as a per-UE capability without any FRx / xDD differentiation. The UE (200) supporting Intra-CU conditional LTM for SCG supports Intra-CU LTM for SCG, i.e. it would inform the gNB (106) that it supports Intra-CU LTM for SCG.

[0197] Configuration handling:In an embodiment herein, the UE (200) keeps the configuration of conditional LTM including the conditions, thresholds, timers, candidate configurations etc. etc., upon LTM cell switch. In an embodiment in TS 38.331.

[0198] 5.3.5.x.6 LTM cell switch execution:Upon the indication by lower layers that an LTM cell switch procedure is triggered, or upon performing LTM cell switch upon to cell selection performed while timer T311 was running, as specified in 5.3.7.3, the UE (200) shall:

[0199] 1> release / clear all current dedicated radio configuration related to cell group to which the LTM cell switch procedure is triggered except for the following:

[0200] 2> if the LTM cell switch is triggered on the MCG:

[0201] - the MCG C-RNTI;

[0202] - the AS security configurations associated with the master key;

[0203] -subsequent CPAC candidate configuration stored in MCG VarConditionalReconfig

[0204] 2> else, if the LTM cell switch is triggered on the SCG:

[0205] - the AS security configurations associated with the secondary key;

[0206] - the SRB1 / SRB2 configurations and DRB configurations as configured by radioBearerConfig or radioBearerConfig2;

[0207] - the RLC entity configuration, which include one or more RLC-BearerConfig IEs;

[0208] - the UE variables VarLTM-Config and VarLTM-UE-Config.

[0209] - the UE variables storing conditional configuration for LTM

[0210] -subsequent CPAC candidate configuration stored in SCG VarConditionalReconfig

[0211] -conditional configuration for LTM.

[0212] NOTE X: Upon an LTM cell switch, the UE (200) shall release the radio bearer(s) that are part of the current UE's configuration but not part of the LTM candidate cell configuration indicated by lower layers.

[0213] 1> release / clear all current common radio configuration related to cell group to which the LTM cell switch procedure is triggered;

[0214] In an embodiment herein, the UE (200) keeps the configuration of conditional LTM including the conditions, thresholds, timers,candidate configurations etc., upon subsequent CPAC execution. In an embodiment herein, the UE keeps the configuration for LTM upon subsequent CPAC execution. In an embodiment in TS 38.331,

[0215] Upon the conditional reconfiguration execution for subsequent CPAC, the UE shall:

[0216] 1> if the selected subsequent CPAC candidate configuration is stored in MCG VarConditionalReconfig:

[0217] 2> release / clear all current dedicated radio configuration except for the following:

[0218] - the MCG C-RNTI;

[0219] - the AS security configurations associated with the master key and the secondary key;

[0220] - for each SRB / DRB in current UE configuration:

[0221] - keep the associated RLC, PDCP and SDAP entities, their state variables, buffers and timers;

[0222] - release all fields related to the SRB / DRB configuration except for srb-Identity and drb-Identity;

[0223] - the UE variables storing conditional configuration for LTM

[0224] -conditional configuration for LTM.

[0225] -all the UE variables related to LTM configuration including the UE variables for storing the configuration for cells among which the UEs can move across without resetting, the configuration for the cells where UE based TA can be applied etc.

[0226] 2> release / clear all current common radio configuration;

[0227] 1> else:

[0228] 2> release / clear all current dedicated radio configuration associated with the SCG except for the following:

[0229] - the AS security configurations associated with the secondary key;

[0230] - for each SRB / DRB in current UE configuration which is using the secondary key:

[0231] - keep the associated RLC, PDCP and SDAP entities, their state variables, buffers and timers;

[0232] - release all fields related to the SRB / DRB configuration except for srb-Identity and drb-Identity;

[0233] - the UE variables VarConditionalReconfig.

[0234] - the UE variables storing conditional configuration for LTM

[0235] -conditional configuration for LTM.

[0236] Conditional LTM and DAPS handover:In an embodiment herein, if the UE (200) performs DAPS handover, the UE (200) releases the configuration for conditional LTM. In an embodiment herein, if DAPS bearer is configured, the gNB (106) skips configuring configuration for conditional LTM. The gNB (106) may release the configuration for conditional LTM, if configured, on configuring DAPS bearer and may add the configuration for conditional LTM again on releasing DAPS bearer. Further, the gNB (106) may release DAPS bearer, while configuring configuration for conditional LTM.

[0237] In an embodiment herein, the source gNB releases configuration for conditional LTM before sending the DAPS handover command to the UE. Target gNB skips configuring configuration for conditional LTM until DAPS handover is completed.

[0238] An example specification change for the above embodiment as per 3gpp specification TS 38.300 is given below.

[0239] Only source and target PCell are used during DAPS handover. CA, DC, SUL, multi-TRP, EHC, CHO, UDC, NR sidelink configurations, V2X sidelink configurations and configuration for conditional LTM are released by the source gNB before the handover command is sent to the UE (200) and are not configured by the target gNB until the DAPS handover has completed (i.e. at earliest in the same message that releases the source PCell).

[0240] Release of configuration for conditional LTM:In an embodiment herein, during RRC Reestablishment procedure (RRC Reestablishment procedure includes the various steps as detailed in 3gpp TS 38.331 section 5.3.7), the UE (200) removes configuration for conditional LTM including the conditions, thresholds, timers,candidate configurations etc. In an embodiment herein, the removal will be performed following cell selection while timer T311 is running.

[0241] In an embodiment herein, the UE (200) removes configuration for conditional LTM including the conditions, thresholds, timers,candidate configurations etc.), during RRC Reestablishment procedure (RRC Reestablishment procedure includes the various steps as detailed in 3gpp TS 38.331 section 5.3.7). This can be performed while T311 is running. Alternatively, it can be performed following cell selection while a Radio Link Failure (RLF) is detected or upon the reception of RRC Reestablishment message.

[0242] In an embodiment herein, during the RRC reestablishment procedure (as in TS 38.331 section 5.3.7), the UE (200) stores the configuration for conditional LTM including the conditions, thresholds, timers, candidate configurations etc. The UE (200) may store the configurations based on a flag received from the network node (106). Further, UE (200) may restore the configuration for conditional LTM including the conditions, thresholds, timers,candidate configurations etc., once the RRC Reestablishment is successful. In an embodiment herein, the UE (200) decides whether to restore or release the configuration for conditional LTM including the conditions, thresholds, timers,candidate configurations etc. based on a flag.

[0243] In an embodiment herein, upon receiving RRC Release or RRC Release with suspend config, the UE (200) releases any configuration for conditional LTM including the conditions, thresholds, timers,candidate configurations etc. In an embodiment herein, the UE (200) may release these during RRC Resume procedure (RRC Resume procedure includes the various steps as detailed in 3gpp TS 38.331 section 5.7.3).

[0244] In an embodiment herein, based on TS 38.331, V18.0.0, the release of conditional LTM configuration is handled as below:

[0245] 5.3.7.2 Initiation: The UE (200) initiates the procedure when one of the following conditions is met:

[0246] 1> upon detecting radio link failure of the MCG and t316 is not configured, in accordance with 5.3.10; or

[0247] 1> upon detecting radio link failure of the MCG while SCG transmission is suspended, in accordance with 5.3.10; or

[0248] 1> upon detecting radio link failure of the MCG while PSCell change or PSCell addition is ongoing, in accordance with 5.3.10; or

[0249] 1> upon detecting radio link failure of the MCG while the SCG is deactivated, in accordance with 5.3.10; or

[0250] 1> upon re-configuration with sync failure of the MCG, in accordance with clause 5.3.5.8.3; or

[0251] 1> upon mobility from NR failure, in accordance with clause 5.4.3.5; or

[0252] 1> upon integrity check failure indication from lower layers concerning SRB1 or SRB2, except if the integrity check failure is detected on the RRCReestablishment message; or

[0253] 1> upon an RRC connection reconfiguration failure, in accordance with clause 5.3.5.8.2; or

[0254] 1> upon detecting radio link failure for the SCG while MCG transmission is suspended, in accordance with clause 5.3.10.3 in NR-DC or in accordance with TS 36.331

[0010] clause 5.3.11.3 in NE-DC; or

[0255] 1> upon reconfiguration with sync failure of the SCG while MCG transmission is suspended in accordance with clause 5.3.5.8.3; or

[0256] 1> upon SCG change failure while MCG transmission is suspended in accordance with TS 36.331

[0010] clause 5.3.5.7a; or

[0257] 1> upon SCG configuration failure while MCG transmission is suspended in accordance with clause 5.3.5.8.2 in NR-DC or in accordance with TS 36.331

[0010] clause 5.3.5.5 in NE-DC; or

[0258] 1> upon integrity check failure indication from SCG lower layers concerning SRB3 while MCG is suspended; or

[0259] 1> upon T316 expiry, in accordance with clause 5.7.3b.5; or

[0260] 1> upon detecting sidelink radio link failure by L2 U2N Remote UE in RRC_CONNECTED, in accordance with clause 5.8.9.3; or

[0261] 1> upon reception of NotificationMessageSidelink including indicationType by L2 U2N Remote UE in RRC_CONNECTED, in accordance with clause 5.8.9.10; or

[0262] 1> upon PC5 unicast link release indicated by upper layer at L2 U2N Remote UE in RRC_CONNECTED while T301 is not running.

[0263] NOTE 0: It is up to UE implementation whether to initiate the procedure while T346g is running.

[0264] Upon initiation of the procedure, the UE (200) shall:

[0265] 1> stop timer T310, if running;

[0266] 1> stop timer T312, if running;

[0267] 1> stop timer T304, if running;

[0268] 1> start timer T311;

[0269] 1> stop timer T316, if running;

[0270] 1> if UE is not configured with attemptCondReconfig; and

[0271] 1> if UE is not configured with attemptLTM-Switch:

[0272] 2> reset MAC;

[0273] 2> release spCellConfig, if configured;

[0274] 2> suspend all RBs, and BH RLC channels for IAB-MT, and Uu Relay RLC channels for L2 U2N Relay UE, except SRB0 and broadcast MRBs;

[0275] 2> release the MCG SCell(s), if configured;

[0276] 2> if MR-DC is configured:

[0277] 3> perform MR-DC release, as specified in clause 5.3.5.10;

[0278] 2> perform the LTM configuration release procedure for the MCG and the SCG as specified in clause 5.3.5.x.7;

[0279] 2> release all configurations related to conditional LTM including conditions, thresholds,timers etc.

[0280] 2> releases UE variables storing configurations related to conditional LTM including conditions, thresholds, timers etc.

[0281] <various other releases according to TS 38.331.>

[0282] <various other releases>

[0283] 1> release successHO-Config, if configured;

[0284] 5.3.7.3 Actions following cell selection while T311 is running

[0285] Upon selecting a suitable NR cell, the UE (200) shall:

[0286] 1> ensure having valid and up to date essential system information as specified in clause 5.2.2.2;

[0287] 1> stop timer T311;

[0288] 1> if T390 is running:

[0289] 2> stop timer T390 for all access categories;

[0290] 2> perform the actions as specified in 5.3.14.4;

[0291] 1> stop the relay (re)selection procedure, if ongoing;

[0292] 1> if the cell selection is triggered by detecting radio link failure of the MCG or re-configuration with sync failure of the MCG or mobility from NR failure, and

[0293] 1> if attemptCondReconfig is configured; and

[0294] 1> if the selected cell is not configured with CondEventT1, or the selected cell is configured with CondEventT1 and leaving condition has not been fulfilled; and

[0295] 1> if the selected cell is one of the candidate cells for which the reconfigurationWithSync is included in the masterCellGroup in the MCG VarConditionalReconfig and the condExecutionCondPSCell is not configured for the corresponding condReconfigId in the MCG VarConditionalReconfig:

[0296] 2> if the UE supports RLF-Report for conditional handover, set the choCellId in the VarRLF-Report to the global cell identity, if available, otherwise to the physical cell identity and carrier frequency of the selected cell;

[0297] 2> apply the stored condRRCReconfig associated to the selected cell and perform actions as specified in 5.3.5.3;

[0298] NOTE 1: It is left to network implementation to how to avoid keystream reuse in case of CHO based recovery after a failed handover without key change.

[0299] 1> if the cell selection is triggered by detecting radio link failure of the MCG or re-configuration with sync failure of the MCG or mobility from NR failure; and

[0300] 1> if attemptLTM-Switch is configured; and

[0301] 1> if the selected cell is one of the LTM candidate cells in the LTM-Candidate IE within VarLTM-Config associated with the MCG:

[0302] 2> perform the LTM cell switch procedure for the selected LTM candidate cell according to the actions specified in 5.3.5.x.6;

[0303] 1> else:

[0304] 2> if UE is configured with attemptCondReconfig; or

[0305] 2> if UE is configured with attemptLTM-Switch:

[0306] 3> reset MAC;3> release spCellConfig, if configured;

[0307] 3> release the MCG SCell(s), if configured;

[0308] 3>various other releases according to TS 38.331.

[0309] 2> remove all the entries within the MCG VarConditionalReconfig, if any;

[0310] 2> perform the LTM configuration release procedure for the MCG and the SCG as specified in clause 5.3.5.x.7;

[0311] 2> release all configurations related to conditional LTM including conditions, thresholds,timers etc.

[0312] 2> releases UE variables storing configurations related to conditional LTM including conditions, thresholds,timers etc.

[0313] 2> for each measId, if the associated reportConfig has a reportType set to condTriggerConfig:

[0314] 3> for the associated reportConfigId:

[0315] 4> remove the entry with the matching reportConfigId from the reportConfigList within the VarMeasConfig;

[0316] 3> if the associated measObjectId is only associated to a reportConfig with reportType set to condTriggerConfig:

[0317] 4> remove the entry with the matching measObjectId from the measObjectList within the VarMeasConfig;

[0318] 3> remove the entry with the matching measId from the measIdList within the VarMeasConfig;

[0319] 2> remove the servingSecurityCellSetId within the VarServingSecurityCellSetID, if any;

[0320] 2> release the PC5 RLC entity for SL-RLC0, if any;

[0321] 2> start timer T301;

[0322] 2> apply the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in SIB1;

[0323] 2> apply the default MAC Cell Group configuration as specified in 9.2.2;

[0324] 2> apply the CCCH configuration as specified in 9.1.1.2;

[0325] 2> apply the timeAlignmentTimerCommon included in SIB1;

[0326] 2> initiate transmission of the RRCReestablishmentRequest message in accordance with 5.3.7.4;

[0327] NOTE 2: This procedure applies also if the UE returns to the source PCell.

[0328] Upon selecting an inter-RAT cell, the UE (200) shall:

[0329] 1> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause 'RRC connection failure'.

[0330] 5.3.7.2 Initiation

[0331] The UE initiates the procedure when one of the following conditions is met:

[0332] 1> upon detecting radio link failure of the MCG and t316 is not configured, in accordance with 5.3.10; or

[0333] 1> upon detecting radio link failure of the MCG while SCG transmission is suspended, in accordance with 5.3.10; or

[0334] 1> upon detecting radio link failure of the MCG while PSCell change or PSCell addition is ongoing, in accordance with 5.3.10; or

[0335] 1> upon detecting radio link failure of the MCG while the SCG is deactivated, in accordance with 5.3.10; or

[0336] 1> upon re-configuration with sync failure of the MCG, in accordance with clause 5.3.5.8.3; or

[0337] 1> upon mobility from NR failure, in accordance with clause 5.4.3.5; or

[0338] 1> upon integrity check failure indication from lower layers concerning SRB1 or SRB2, except if the integrity check failure is detected on the RRCReestablishment message; or

[0339] 1> upon an RRC connection reconfiguration failure, in accordance with clause 5.3.5.8.2; or

[0340] 1> upon detecting radio link failure for the SCG while MCG transmission is suspended, in accordance with clause 5.3.10.3 in NR-DC or in accordance with TS 36.331

[0010] clause 5.3.11.3 in NE-DC; or

[0341] 1> upon reconfiguration with sync failure of the SCG while MCG transmission is suspended in accordance with clause 5.3.5.8.3; or

[0342] 1> upon SCG change failure while MCG transmission is suspended in accordance with TS 36.331

[0010] clause 5.3.5.7a; or

[0343] 1> upon SCG configuration failure while MCG transmission is suspended in accordance with clause 5.3.5.8.2 in NR-DC or in accordance with TS 36.331

[0010] clause 5.3.5.5 in NE-DC; or

[0344] 1> upon integrity check failure indication from SCG lower layers concerning SRB3 while MCG is suspended; or

[0345] 1> upon T316 expiry, in accordance with clause 5.7.3b.5; or

[0346] 1> upon detecting sidelink radio link failure by L2 U2N Remote UE in RRC_CONNECTED, in accordance with clause 5.8.9.3; or

[0347] 1> upon reception of NotificationMessageSidelink including indicationType by L2 U2N Remote UE in RRC_CONNECTED, in accordance with clause 5.8.9.10; or

[0348] 1> upon PC5 unicast link release indicated by upper layer at L2 U2N Remote UE in RRC_CONNECTED while T301 is not running.

[0349] NOTE 0: It is up to UE implementation whether to initiate the procedure while T346g is running.

[0350] Upon initiation of the procedure, the UE shall:

[0351] 1> stop timer T310, if running;

[0352] 1> stop timer T312, if running;

[0353] 1> stop timer T304, if running;

[0354] 1> start timer T311;

[0355] 1> stop timer T316, if running;

[0356] 1> if UE is not configured with attemptCondReconfig; and

[0357] 1> if UE is not configured with attemptLTM-Switch:

[0358] 2> reset MAC;

[0359] 2> release spCellConfig, if configured;

[0360] 2> suspend all RBs, and BH RLC channels for IAB-MT, and Uu Relay RLC channels for L2 U2N Relay UE, except SRB0 and broadcast MRBs;

[0361] 2> release the MCG SCell(s), if configured;

[0362] 2> if MR-DC is configured:

[0363] 3> perform MR-DC release, as specified in clause 5.3.5.10;

[0364] 2> perform the LTM configuration release procedure for the MCG and the SCG as specified in clause 5.3.5.x.7;

[0365] 2> release all configurations related to conditional LTM including conditions, thresholds,timers etc.

[0366] 2> releases UE variables storing configurations related to conditional LTM including conditions,thresholds,timers etc.

[0367] <various Releases according to TS 38.331>

[0368] 5.3.7.3 Actions following cell selection while T311 is running

[0369] Upon selecting a suitable NR cell, the UE (200) shall:

[0370] 1> if the cell selection is triggered by detecting radio link failure of the MCG or re-configuration with sync failure of the MCG or mobility from NR failure; and

[0371] 1> if attemptLTM-Switch is configured; and

[0372] 1> if the selected cell is one of the LTM candidate cells in the LTM-Candidate IE within VarLTM-Config associated with the MCG:

[0373] 2> perform the LTM cell switch procedure for the selected LTM candidate cell according to the actions specified in 5.3.5.x.6;

[0374] 1> else:

[0375] 2> if UE is configured with attemptCondReconfig; or

[0376] 2> if UE is configured with attemptLTM-Switch:

[0377] 3> reset MAC;

[0378] 2> remove all the entries within the MCG VarConditionalReconfig, if any;

[0379] 2> perform the LTM configuration release procedure for the MCG and the SCG as specified in clause 5.3.5.x.7;

[0380] 2> release all configurations related to conditional LTM including conditions, thresholds,timers etc.

[0381] 2> releases UE variables storing configurations related to conditional LTM including conditions,thresholds,timers etc.

[0382] 2> start timer T301;

[0383] 2> apply the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in SIB1;

[0384] 2> apply the default MAC Cell Group configuration as specified in 9.2.2;

[0385] 2> apply the CCCH configuration as specified in 9.1.1.2;

[0386] 2> apply the timeAlignmentTimerCommon included in SIB1;

[0387] 2> initiate transmission of the RRCReestablishmentRequest message in accordance with 5.3.7.4;

[0388] NOTE 2: This procedure applies also if the UE (200) returns to the source PCell.

[0389] Upon selecting an inter-RAT cell, the UE (200) shall:

[0390] 1> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause 'RRC connection failure'.

[0391] 5.3.8.3 Reception of the RRCRelease by the UE

[0392] The UE (200) shall:

[0393] 1> delay the following actions defined in this clause 60 ms from the moment the RRCRelease message was received or optionally when lower layers indicate that the receipt of the RRCRelease message has been successfully acknowledged, whichever is earlier;

[0394] 1> stop timer T380, if running;

[0395] 1> stop timer T320, if running;

[0396] 1> if timer T316 is running;

[0397] 2> stop timer T316;

[0398] 2> clear the information included in VarRLF-Report, if any;

[0399] 1> stop timer T350, if running;

[0400] 1> stop timer T346g, if running;

[0401] 1> if the AS security is not activated:

[0402] 2> ignore any field included in RRCRelease message except waitTime;

[0403] 2> perform the actions upon going to RRC_IDLE as specified in 5.3.11 with the release cause 'other' upon which the procedure ends;

[0404] 1> if the RRCRelease message includes redirectedCarrierInfo indicating redirection to eutra:

[0405] 2> if cnType is included:

[0406] 3> after the cell selection, indicate the available CN Type(s) and the received cnType to upper layers;

[0407] NOTE 1: Handling the case if the E-UTRA cell selected after the redirection does not support the core network type specified by the cnType, is up to UE implementation.

[0408] 2> if voiceFallbackIndication is included:

[0409] 3> consider the RRC connection release was for EPS fallback for IMS voice (see TS 23.502

[0043] );

[0410] 1> if the RRCRelease message includes the cellReselectionPriorities:

[0411] 2> store the cell reselection priority information provided by the cellReselectionPriorities;

[0412] 2> if the t320 is included:

[0413] 3> start timer T320, with the timer value set according to the value of t320;

[0414] 1> else:

[0415] 2> apply the cell reselection priority information broadcast in the system information;

[0416] 1> if deprioritisationReq is included and the UE (200) supports RRC connection release with deprioritisation:

[0417] 2> start or restart timer T325 with the timer value set to the deprioritisationTimer signalled;

[0418] 2> store the deprioritisationReq until T325 expiry;

[0419] NOTE 1a: The UE (200) stores the deprioritisation request irrespective of any cell reselection absolute priority assignments (by dedicated or common signalling) and regardless of RRC connections in NR or other RATs unless specified otherwise.

[0420] 1> if the RRCRelease includes the measIdleConfig:

[0421] 2> if T331 is running:

[0422] 3> stop timer T331;

[0423] 3> perform the actions as specified in 5.7.8.3;

[0424] 2> if the measIdleConfig is set to setup:

[0425] 3> store the received measIdleDuration in VarMeasIdleConfig;

[0426] 3> start timer T331 with the value set to measIdleDuration;

[0427] 3> if the measIdleConfig contains measIdleCarrierListNR:

[0428] 4> store the received measIdleCarrierListNR in VarMeasIdleConfig;

[0429] 3> if the measIdleConfig contains measIdleCarrierListEUTRA:

[0430] 4> store the received measIdleCarrierListEUTRA in VarMeasIdleConfig;

[0431] 3> if the measIdleConfig contains validityAreaList:

[0432] 4> store the received validityAreaList in VarMeasIdleConfig;

[0433] 1> if the RRCRelease includes suspendConfig:

[0434] 2> reset MAC and release the default MAC Cell Group configuration, if any;

[0435] 2> apply the received suspendConfig except the received nextHopChainingCount;

[0436] 2> if the sdt-Config is configured:

[0437] 3> for each of the DRB in the sdt-DRB-List:

[0438] 4> consider the DRB to be configured for SDT;

[0439] 3> if sdt-SRB2-Indication is configured:

[0440] 4> consider the SRB2 to be configured for SDT;

[0441] 3> for each RLC bearer (except those associated with broadcast MRBs) that is not suspended:

[0442] 4> re-establish the RLC entity as specified in TS 38.322 [4];

[0443] 3> for SRB2 (if it is resumed) and for SRB1:

[0444] 4> trigger the PDCP entity to perform SDU discard as specified in TS 38.323 [5];

[0445] 3> if sdt-MAC-PHY-CG-Config is configured:

[0446] 4> configure the PCell with the configured grant resources for SDT and instruct the MAC entity to start the cg-SDT-TimeAlignmentTimer;

[0447] 2> if srs-PosRRC-Inactive is configured:

[0448] 3> apply the configuration and instruct MAC to start the inactivePosSRS-TimeAlignmentTimer;

[0449] NOTE 1b: The network node (106) should provide full configuration to the UE (200) for SRS for Positioning in RRC_INACTIVE.

[0450] 2> perform the LTM configuration release procedure for the MCG and the SCG as specified in clause 5.3.5.x.7;

[0451] 2> release all configurations related to conditional LTM including conditions, thresholds,timers etc.

[0452] 2> releases UE variables storing configurations related to conditional LTM including conditions,thresholds,timers etc.

[0453] 2> remove all the entries within the MCG and the SCG VarConditionalReconfig, if any;

[0454] 2> remove the servingSecurityCellSetId within the VarServingSecurityCellSetID, if any;

[0455] 5.3.11 UE actions upon going to RRC_IDLE

[0456] The UE (200) shall:

[0457] 1> reset MAC;

[0458] 1> set the variable pendingRNA-Update to false, if that is set to true;

[0459] <various releases as in TS 38.331>

[0460] 1> release the suspendConfig, if configured;

[0461] 1> perform LTM configuration release procedure for the MCG and SCG as specified in clause 5.3.5.x.7;

[0462] 1> remove all the entries within the MCG and the SCG VarConditionalReconfig, if any;

[0463] 1> remove the servingSecurityCellSetId within the VarServingSecurityCellSetID, if any;

[0464] 1> release all configurations related to conditional LTM including conditions, thresholds, timers, candidate configurations etc.

[0465] 1> releases UE variables storing configurations related to conditional LTM including conditions, thresholds, timers, candidate configurations etc.

[0466] In an embodiment herein, the network node (such as the gNB) (106) avoids configuring the UE (200) with relaxed measurement configuration in LTM configuration or a RRCReconfiguration including reconfigurationwithsync which configures RACHless handover such the NTN configuration. In an embodiment herein, the UE (200) does not perform relaxed measurements for low mobility or stationery UEs in a cell, in which it has been moved to through RACHless handover or RACHless cell switch.

[0467] In an embodiment herein, lowMobilityEvaluationConnectedLTM-r19, goodServingCellEvaluationRLM-r17, goodServingCellEvaluationBFD-r17 will not be configured in an LTM candidate configuration. In an embodiment herein, SSearchDeltaP-StationaryConnected, TSearchDeltaP-Connected, SS-RSRPRefStationaryConnected and TSearchDeltaP-StationaryConnected will not be configured in an LTM candidate configuration or LTM reference configuration.

[0468] In an embodiment herein, lowMobilityEvaluationConnectedLTM-r19, goodServingCellEvaluationRLM-r17, goodServingCellEvaluationBFD-r17 will not be configured for mobility where the UE (200) performs RACHless handover or cell switch. In an embodiment SSearchDeltaP-StationaryConnected, TSearchDeltaP-Connected, SS-RSRPRefStationaryConnected and TSearchDeltaP-StationaryConnected will not be configured for mobility where the UE (200) performs RACHless handover or cell switch.

[0469] LTM configuration in dual connectivity: In an embodiment herein, the network node (such as the gNB) (106) receives information form the OAM whether it can configure LTM. The network node (such as the gNB) (106) configures the UE LTM based on received information from OAM.

[0470] In an embodiment herein, the network node (such as the gNB) receives information form OAM whether it can configure MCG LTM. The network node (such as the gNB) (106) configures the UE LTM based on received information from OAM.

[0471] In an embodiment herein, the network node (such as the gNB) (106) receives information form OAM whether it can configure SCG LTM. The network node (such as the gNB) (106) configures the UE LTM based on received information from OAM.

[0472] In an embodiment herein, the network node (such as the gNB) (106) receives information form OAM whether it can configure LTM while it is MN. The network node (such as the gNB) (106) configures the UE LTM based on received information from OAM.

[0473] In an embodiment herein, the network node (such as the gNB) (106) receives information form OAM whether it can configure LTM while it is SN. The network node (such as the gNB) (106) configures the UE LTM based on received information from OAM.

[0474] LTM measurement configuration:

[0475] Embodiments herein list the methods for configuring the LTM measurement configuration by MN and SN in dual connectivity below. In an embodiment herein, the SN configures only the frequencies that either MN or SN has configured for L3 measurements as frequencies for LTM measurements.

[0476] In an embodiment herein, the SN configures the same reference signals that either MN or SN has configured for L3 measurements for a frequency, as the reference signal for LTM measurements for the same frequency.

[0477] In an embodiment herein, the MN configures only the frequencies that either the MN or the SN has configured for L3 measurements as frequencies for LTM measurements.

[0478] In an embodiment herein, the MN configures the same reference signals that either the MN or the SN has configured for L3 measurements for a frequency, as the reference signal for LTM measurements for the same frequency.

[0479] In an embodiment herein, the SN configures only the frequencies that SN has configured for L3 measurements as frequencies for LTM measurements.

[0480] In an embodiment herein, the SN configures the same reference signals that the SN has configured for L3 measurements for a frequency, as the reference signal for LTM measurements for the same frequency.

[0481] In an embodiment herein, the MN configures only the frequencies that the MN has configured for L3 measurements as frequencies for LTM measurements.

[0482] In an embodiment herein, the MN configures the same reference signals that the MN has configured for L3 measurements for a frequency, as the reference signal for LTM measurements for the same frequency.

[0483] SN Initiated PSCell Change configuration:In an embodiment herein, sn-InitiatedPSCellChange is provided as a Need N parameter. The UE (200) applies the value and doesn't maintain the value.

[0484] MN Initiated PSCell Change configuration:In an embodiment herein, a network node (such as, the gNB) informs the UE (200) if the Reconfiguration message triggering ReconfigurationWithSync for a PSCellChange is MN initiated using an enumerated value (a flag). In NR, the gNB (106) may include a field (e.g. mn-InitiatedPSCellChange) in OtherConfig. If this field (mn-InitiatedPSCellChange) is included, ( i.e. if the field is set as true), the UE (200) identifies the Reconfiguration message is MN initiated. On the other hand, if the field is not included, the UE (200) identifies the PSCell change as SN initiated. In an embodiment herein, mn-InitiatedPSCellChange is provided as a Need N parameter. The UE (200) does not maintain the value.

[0485] In an embodiment herein, the UE (200) (which has received OtherConfig including SPR configuration) maintains the SPR configuration even when receiving OtherConfig without SPR configuration and releases this configuration after receiving a configuration which explicitly releases SPR configuration.

[0486] In an embodiment herein, sn-InitiatedPSCellChange and mn-InitiatedPSCellChange are included in RRCReconfiguration IEs rather than in OtherConfig.

[0487] In an embodiment herein, the UE (200) which has performed the random access using slicing specific or AI specific RACH parameters avoids storing the RA-InformationCommon in the RA-Report or storing the RA-Report.

[0488] In an embodiment herein, the UE (200) which has performed the random access using feature specific RACH and the used features are eRedCap or msg1-repetition, avoids storing the RA-InformationCommon in the RA-Report or storing the RA-Report.

[0489] In an embodiment herein, the UE (200) includes RSSI measurements, and the UE (200) may log and report the measurement object identifier in the RLF report or Successful Handover Report along with measurement results of neighboring frequencies.

[0490] FIG. 4a shows various hardware components of the UE (200), according to embodiments as disclosed herein. In an embodiment, the UE (200) includes a processor (410a), a communicator (420a), a memory (430a), and a conditional LTM handling controller (440a). The processor (410a) is coupled with the communicator (420a), the memory (430a), and the conditional LTM handling controller (440a).

[0491] The conditional LTM handling controller (440a) receives a conditional LTM configuration for executing the LTM cell switch. The conditional LTM configuration includes the one or more conditions. The conditional LTM configuration includes the LTM candidate configuration for at least one candidate cell, and the timer for measuring the one or more reference signals of the at least one candidate cell and at least one serving cell. The one or more conditions comprises threshold values of measurements of the one or more reference signals. The measurements of the one or more reference signals comprise at least one of a RSRP, a RSRQ, and a Signal to Interference and Noise Ratio (SINR).

[0492] Further, the conditional LTM handling controller (440a) measures one or more reference signals of at least one candidate cell and at least one serving cell. The serving cell can be PCell (Primary Cell) in MCG LTM or PSCell (Primary Secondary CellGroup Cell) in SCG LTM. Further, the conditional LTM handling controller (440a) execute the LTM switch if one or more measured values of the one or more reference signals satisfy the one or more received conditions.

[0493] The conditional LTM handling controller (440a) executes the LTM cell switch if the threshold values of the one or more reference signals are met within the duration of the timer.

[0494] Further, the conditional LTM handling controller (440a) sends the UE capability information related to the conditional LTM to the network node (106). The UE capability information indicates whether the UE (200) supports at least one of the conditional LTM, and the Inter-Centralized Unit (CU) conditional LTM. The UE capability information indicates whether the UE (200) supports the conditional LTM for at least one of the MCG, and the SCG. Further, the conditional LTM handling controller (440a) receives the conditional LTM configuration from the network node (106), based on the received UE capability information.

[0495] Further, the conditional LTM handling controller (440a) releases the conditional LTM configuration, during a Radio Resource Control (RRC) reestablishment procedure. The conditional LTM configuration is released following a cell selection while at least one of a timer T311 is running, a Radio Link Failure (RLF) is detected, and on receiving an RRC reestablishment message.

[0496] Further, the conditional LTM handling controller (440a) releases the conditional LTM configuration, during an RRC inactive transition, on receiving an RRC release message including suspend configuration.

[0497] The conditional LTM handling controller (440a) 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, hardwired circuits and the like, and may optionally be driven by firmware.

[0498] The processor (410a) may include one or a plurality of processors. The one or the plurality of processors may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The processor (410a) may include multiple cores and is configured to execute the instructions stored in the memory (430a).

[0499] Further, the processor (410a) is configured to execute instructions stored in the memory (430a) and to perform various processes. The communicator (420a) is configured for communicating internally between internal hardware components and with external devices via one or more networks. The memory (430a) also stores instructions to be executed by the processor (410a). The memory (430a) may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In addition, the memory (430a) may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term "non-transitory" should not be interpreted that the memory (430a) is non-movable. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0500] Although FIG. 4a shows various hardware components of the UE (200) but it is to be understood that other embodiments are not limited thereon. In other embodiments, the UE (200) may include less or more number of components. Further, the labels or names of the components are used only for illustrative purposes and does not limit the scope of the invention. One or more components can be combined together to perform the same or substantially similar function in the UE (200).

[0501] FIG. 4b shows various hardware components of the network node (106), according to embodiments as disclosed herein. In an embodiment, the network node (106) includes a processor (410b), a communicator (420b), a memory (430), and a conditional LTM handling controller (440b). The processor (110) is coupled with the communicator (120), the memory (130), and the conditional LTM handling controller (440b).

[0502] The conditional LTM handling controller (440b) skips configuration of the conditional LTM configuration, if a Dual Active Protocol Stack (DAPS) bearer is configured in the network node (106). The network node (106)skips configuring the conditional LTM configuration until a DAPS handover is completed. In another embodiment, the conditional LTM handling controller (440b) releases the conditional LTM configuration, if configured, on configuring the DAPS bearer, wherein a source base station releases the conditional LTM configuration before sending a DAPS handover command to the UE. In another embodiment, the conditional LTM handling controller (440b) adds the conditional LTM configuration, on releasing the configured DAPS bearer. In another embodiment, the conditional LTM handling controller (440b) releases the configured DAPS bearer, while configuring the conditional LTM configuration.

[0503] The conditional LTM handling controller (440b) 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, hardwired circuits and the like, and may optionally be driven by firmware.

[0504] The processor (410b) may include one or a plurality of processors. The one or the plurality of processors may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The processor (410b) may include multiple cores and is configured to execute the instructions stored in the memory (430b).

[0505] Further, the processor (410b) is configured to execute instructions stored in the memory (430b) and to perform various processes. The communicator (420b) is configured for communicating internally between internal hardware components and with external devices via one or more networks. The memory (430b) also stores instructions to be executed by the processor (410b). The memory (430b) may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In addition, the memory (430b) may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term "non-transitory" should not be interpreted that the memory (430b) is non-movable. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0506] Although FIG. 4b shows various hardware components of the network node (106) but it is to be understood that other embodiments are not limited thereon. In other embodiments, the network node (106) may include less or more number of components. Further, the labels or names of the components are used only for illustrative purposes and does not limit the scope of the invention. One or more components can be combined together to perform the same or substantially similar function in the network node (106).

[0507] FIG. 5 is a flow chart illustrating a method for managing conditional the LTM by the UE 200, according to embodiments as disclosed herein.

[0508] The method S500 comprises receiving the conditional LTM configuration for executing an LTM cell switch, as depicted in step S502. The conditional LTM configuration comprises one or more conditions such as threshold values of measurements of the reference signals. The method S500 comprises measuring one or more reference signals of at least one candidate cell and at least one serving cell, as depicted in step S504. The serving cell can be PCell (Primary Cell) in MCG LTM or PSCell (Primary Secondary CellGroup Cell) in SCG LTM. The measurements of the reference signals can include, but not limited to, RSRP, RSRQ, and SINR.

[0509] Thereafter, the method S500 comprises executing the LTM switch if one or more measured values of the reference signals satisfy the received conditions, as depicted in step S506.

[0510] The various actions in method S500 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 5 may be omitted.

[0511] FIG. 6 depicts the process of Conditional LTM configuration, according to embodiments as disclosed herein.

[0512] In step 6-1, the gNB 106 transmits an RRC reconfiguration message including a conditional LTM configuration to the UERRC. The LTM configuration includes thresholds, timers, conditions, candidate configurations, and so on to be executed upon condition satisfaction. In step 6-2, the UE applies the conditional LTM configuration if the conditions are satisfied, and transmits an RRC reconfiguration complete message to the gNB. In step 6-3, the UE performs LTM (L1) measurements, and evaluates conditions. In step 6-4, the UE L1 / L2 triggers an LTM cell switch (if conditions are satisfied). In step 6-5, the UE transmits an RRC reconfiguration complete message to the gNB, on completing the LTM cell switch.

[0513] FIG. 7 depicts an example process S700 for managing conditional LTM by the UE 200, according to embodiments as disclosed herein. The UE 200 receives a conditional LTM configuration including timers, thresholds, conditions, candidate configurations, from the network node (106), as depicted in step S702. The UE 200 performs an RRC release / reestablishment / RRC resume procedure on receiving the conditional LTM configuration, as depicted in step S704. The UE 200 releases conditional LTM configuration for Master Cell Group (MCG) and a Secondary Cell Group (SCG) including timers, thresholds, conditions, candidate configurations, as depicted in step S706.

[0514] The various actions in method S700 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in FIG. 7 may be omitted.

[0515] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The elements shown include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.

[0516] The embodiment disclosed herein describes methods and systems for configuring lower layer triggered mobility and conditional lower layer triggered mobility by the gNB (106) and handling the configurations by the UE. Therefore, it is understood that the scope of the protection is extended to such a program and in addition to a computer readable means having a message therein, such computer readable storage means contain program code means for implementation of one or more steps of the method, when the program runs on a server or mobile deviceor any suitable programmable device. The method is implemented in at least one embodiment through or together with a software program written in e.g., Very high speed integrated circuit Hardware Description Language (VHDL) another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of portable device that can be programmed. The device may also include means which could be e.g., hardware means like e.g., an ASIC, or a combination of hardware and software means, e.g. an ASIC and an FPGA, or at least one microprocessor and at least one memory with software modules located therein. The method embodiments described herein could be implemented partly in hardware and partly in software. Alternatively, the invention may be implemented on different hardware devices, e.g., using a plurality of CPUs.

[0517] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a terminal in a wireless communication system, the method comprising:receiving, from a base station, a first message comprising information on a conditional LTM (L1 / L2(layer 1 / layer 2) triggered mobility) configuration, wherein the information on the LTM configuration comprises information on at least one LTM candidate cell and information on at least one execution conidiation for a conditional LTM cell switch of the at least one LTM candidate cell;in case that the at least one execution condition for a LTM cell among the at least one LTM candidate cell is fulfilled, identifying the LTM cell and triggering a LTM cell switch to the identified LTM cell; andtransmitting, to the LTM cell, a second message for completion of the conditional LTM cell switch to the identified LTM cell.2.The method of claim 1,wherein the first message comprises a radio resource control (RRC) reconfiguration message, andwherein the at least one execution condition comprises at least one measurement result of the at least one LTM candidate cell becomes worse than a first threshold and the at least one measurement result of the at least one LTM candidate cell becomes better than a second threshold.3.The method of claim 1, further comprising:transmitting, to the base station, information indicating whether the terminal supports the conditional LTM cell switch.4.The method of claim 1,wherein the information on the LTM configuration is released in case that at least one of the terminal performs a dual active protocol stack (DAPS) handover, the terminal receives information indicating to release the information on the LTM configuration from the base station, the terminal receives configuration information on a DAPS handover, the terminal performs a radio resource control (RRC) reestablishment procedure, or the terminal receives a an RRC release message.5.A method performed by a base station in a wireless communication system, the method comprising:transmitting, to a terminal, a first message comprising information on a conditional LTM (L1 / L2(layer 1 / layer 2) triggered mobility) configuration, wherein the information on the LTM configuration comprises information on at least one LTM candidate cell and information on at least one execution conidiation for a conditional LTM cell switch of the at least one LTM candidate cell; andreceiving, from a LTM cell, a second message indicating that the terminal has successfully accessed the LTM cell,wherein in case that the at least one execution condition for the LTM cell among the at least one LTM candidate cell is fulfilled, the LTM cell is identified and a LTM cell switch to the identified LTM cell is triggered.6.The method of claim 5,wherein the first message comprises a radio resource control (RRC) reconfiguration message, andwherein the at least one execution condition comprises at least one measurement result of the at least one LTM candidate cell becomes worse than a first threshold and the at least one measurement result of the at least one LTM candidate cell becomes better than a second threshold.7.The method of claim 5, further comprising:receiving, from the terminal, information indicating whether the terminal supports the conditional LTM cell switch.8.The method of claim 5,wherein the information on the LTM configuration is released in case that at least one of the terminal performs a dual active protocol stack (DAPS) handover, the terminal receives information indicating to release the information on the LTM configuration from the base station, the terminal receives configuration information on a DAPS handover, the terminal performs a radio resource control (RRC) reestablishment procedure, or the terminal receives a an RRC release message.9.A terminal in a wireless communication system, the terminal comprising:a transceiver; anda controller coupled with the transceiver and configured to:receive, from a base station, a first message comprising information on a conditional LTM (L1 / L2(layer 1 / layer 2) triggered mobility) configuration, wherein the information on the LTM configuration comprises information on at least one LTM candidate cell and information on at least one execution conidiation for a conditional LTM cell switch of the at least one LTM candidate cell,in case that the at least one execution condition for a LTM cell among the at least one LTM candidate cell is fulfilled, identify the LTM cell and trigger a LTM cell switch to the identified LTM cell, andtransmit, to the LTM cell, a second message for completion of the conditional LTM cell switch to the identified LTM cell.10.The terminal of claim 9,wherein the first message comprises a radio resource control (RRC) reconfiguration message, andwherein the at least one execution condition comprises at least one measurement result of the at least one LTM candidate cell becomes worse than a first threshold and the at least one measurement result of the at least one LTM candidate cell becomes better than a second threshold.11.The terminal of claim 9, wherein the controller is further configured to:transmit, to the base station, information indicating whether the terminal supports the conditional LTM cell switch.12.The terminal of claim 9,wherein the information on the LTM configuration is released in case that at least one of the terminal performs a dual active protocol stack (DAPS) handover, the terminal receives information indicating to release the information on the LTM configuration from the base station, the terminal receives configuration information on a DAPS handover, the terminal performs a radio resource control (RRC) reestablishment procedure, or the terminal receives a an RRC release message.13.A base station in a wireless communication system, the base station comprising:a transceiver; anda controller coupled with the transceiver and configured to:transmit, to a terminal, a first message comprising information on a conditional LTM (L1 / L2(layer 1 / layer 2) triggered mobility) configuration, wherein the information on the LTM configuration comprises information on at least one LTM candidate cell and information on at least one execution conidiation for a conditional LTM cell switch of the at least one LTM candidate cell, andreceive, from a LTM cell, a second message indicating that the terminal has successfully accessed the LTM cell,wherein in case that the at least one execution condition for the LTM cell among the at least one LTM candidate cell is fulfilled, the LTM cell is identified and a LTM cell switch to the identified LTM cell is triggered.14.The base station of claim 13,wherein the first message comprises a radio resource control (RRC) reconfiguration message, andwherein the at least one execution condition comprises at least one measurement result of the at least one LTM candidate cell becomes worse than a first threshold and the at least one measurement result of the at least one LTM candidate cell becomes better than a second threshold.15.The base station of claim 13, wherein the controller is further configured to:receive, from the terminal, information indicating whether the terminal supports the conditional LTM cell switch, andwherein the information on the LTM configuration is released in case that at least one of the terminal performs a dual active protocol stack (DAPS) handover, the terminal receives information indicating to release the information on the LTM configuration from the base station, the terminal receives configuration information on a DAPS handover, the terminal performs a radio resource control (RRC) reestablishment procedure, or the terminal receives a an RRC release message.

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