Handling of conditional handover with candidate scg in wireless communication network

Abstract

Embodiments herein provide a method for handling a CHO with a candidate SCG in a wireless network. The method includes receiving, by a UE (100), a conditional reconfiguration configuration for the CHO and information for attempting a conditional reconfiguration upon an RLF. Further detecting whether the RLF has occurred. Further, selecting a cell for which a conditional reconfiguration for the CHO is configured when the RLF has occurred. The selection is performed while a timer is active. Further, performing one skipping the conditional reconfiguration based on the conditional reconfiguration configured for the CHO for the selected cell, the conditional reconfiguration configured for the CHO is the conditional reconfiguration configured for the CHO with the candidate SCG. In addition, initiating a transmission of a RRC reestablishment request message to the network apparatus, the conditional reconfiguration is not configured for the CHO without the candidate SCG for the selected cell.

Description

HANDLING OF CONDITIONAL HANDOVER WITH CANDIDATE SCG IN WIRELESS COMMUNICATION NETWORK

[0001] The present disclosure is related to wireless communication network systems. More particularly, the present disclosure is related to a method and system for handling of a Conditional Handover (CHO) with a candidate Secondary Cell Group (SCG) in the wireless communication network system.

[0002]

[0003] In wireless technologies like 5th Generation (5G) New Radio (NR), devices can move across different cells.

[0004] In RRC_IDLE mode, mobility is accomplished using a process known as cell reselection. Mobility is carried out using a process known as handover in RRC_CONNECTED mode up till NR R17. Network-controlled mobility is applicable to RRC_CONNECTED user equipment (UEs). The next generation Node B (gNB) in NR must explicitly initiate Radio Resource Control (RRC) signalling. In NR, the handover process typically includes of three stages: preparation, execution, and completion. The UE can be configured by the gNB to submit measurements. Then, the gNB will send the RRC reconfiguration message to transfer the UE from the source cell to the destination cell, depending on the measurements reported or on its own perception of the network topology. The UE accesses the target cell and sends a complete RRC reconfiguration complete. In an alternative way introduced in 3rd Generation Partnership Project (3GPP) NR Release 16, known as conditional handover, CHO, gNB may configure the UE with the execution conditions for triggering handover, and once the execution conditions are satisfied, the UE may move to the target cell and send the RRC reconfiguration complete.

[0005] Further, a lot of these manual tasks must be carried out again if a new service is added or a neighbor gNB is built. 3GPP has implemented self-organizing networks (SON) approaches in wireless technologies such as NR to address this issue. In LTE, SON was initially introduced in 3GPP Release 9. The three types of SON solutions are self-configuration, self-optimization, and self-healing. The SON architecture might be a distributed, hybrid, or centralized system. Mobility robustness optimization (MRO), which lessens the driving test, is a key component of SON. For the goal of self-optimization, the　UE records and reports a variety of data in the Successful Handover Report (SHR), Radio Link Failure (RLF) Report, Success PSCell change or addition information report (SPR) and other reports.

[0006] In traditional wireless systems, networks cannot configure SCG candidate cells within a CHO configuration. This causes considerable delays for the addition and change of PSCells, which adversely affects the UE performance in dual connectivity scenarios. Hence, 3GPP is introducing CHO, including target MCGs and candidate SCGs, in NR Release 18. CHO, including target MCG and candidate SCGs, is a handover procedure in the NR-DC scenario that is executed only when the execution condition(s) of candidate PCells and the execution condition(s) of PSCells are met. This procedure may also be called CHO with the candidate SCG(s).

[0007] If the UE attempts to perform CHO with candidate SCG(s) after a radio link failure, the PSCell may not be suitably strong which may lead to SCG failures immediately after the CHO.

[0008] Current SON algorithms don't support CHO with the candidate SCG(s). Thus, it is desired to address the above-mentioned disadvantages, issues, or other shortcomings, or at least provide a useful alternative.

[0009]

[0010] The principal object of the embodiments herein is to provide handling of a CHO with a candidate SCG in a wireless communication network system.

[0011] Yet another objective of the embodiments herein is to disclose methods and systems for attempting conditional reconfiguration during cell selection after RLF, when CHO with candidate SCG(s) are configured.

[0012] Yet another objective of the embodiment herein is to disclose the handling of an attemptCondReconfig flag in the UE when the conditional handover with candidate SCG is configured and / or where the conditional handover is configured, and the conditional reconfiguration message includes SCG configuration.

[0013]

[0014] In one aspect, the objectives are achieved by a method for handling a CHO with a candidate SCG in a wireless communication network system. The method includes receiving, by a UE, a conditional reconfiguration configuration for the CHO and information for attempting a conditional reconfiguration upon an RLF. Further, the method includes detecting, by the UE, whether the RLF has occurred. Further, the method includes selecting, by the UE, a cell for which a conditional reconfiguration for the CHO is configured when the RLF has occurred. The selection is performed while a timer is active. Further, the method includes performing, by the UE, that the UE has skipped the conditional reconfiguration based on the conditional reconfiguration configured for the CHO for the selected cell. The conditional reconfiguration configured for the CHO is the conditional reconfiguration configured for the CHO with the candidate SCG. Further, the method includes performing, by the UE, that the UE has initiated a transmission of a RRC reestablishment request message to the network apparatus. The conditional reconfiguration is not configured for the CHO without the candidate SCG for the selected cell.

[0015] In an embodiment, the method includes the timer NR timer, which is a T311 timer.

[0016] In an embodiment, the method includes the selected cell as a target candidate cell, and the selected cell is the first cell selected after detection of the failure.

[0017] In an embodiment, the method includes detecting, by the UE, whether a RLF failure or conditions for logging of the SHR and a SCG failure have occurred or whether conditions for logging of the SPR have occurred. Further, the method includes performing, by the UE, that the UE stores SCG information when the RLF failure or conditions for logging of SHR have occurred, transmitting the stored SCG information to a network apparatus in the wireless network. Further, the method includes performing, by the UE, that the UE stores Master Cell Group (MCG) information when the SCG failure or conditions for logging of SPR are detected, and transmitting the SCG information to the network apparatus in the wireless network. In an embodiment, the method includes the storing and transmitting SCG information, which comprises at least one of the neighbor measurements of the SCG cells, a list of SCG conditions associated with the neighbors of the SCG cells, events fulfilled for the candidate SCG and time elapsed between SCG events for neighbor, associated PCells in the same conditional reconfiguration as SCG neighbor cells, which are candidate PSCells, a time elapsed between the fulfilment of SCG and MCG conditions; whether a PCell condition or a PSCell condition is satisfied for associated PCells or conditional reconfigurations; a first satisfied PSCell event when the PCell event is satisfied first; a time elapsed between the fulfilment of the first fulfilled PCell event and the second satisfied PSCell event when the PCell event is satisfied first.

[0018] In an embodiment, the method includes storing and transmitting the MCG information, which comprises neighbor measurements, a list of MCG conditions associated with neighbors, events fulfilled for MCG, a time elapsed between MCG events, associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, a time elapsed between the fulfilment of SCG and MCG conditions, event information, and an order of events.

[0019] Accordingly, the embodiment herein is to provide a UE for handling CHO with a candidate SCG(s) in a wireless communication network system. The UE comprises a memory comprising information about a network apparatus in the wireless network system, a processor, and a CHO optimization controller. The CHO optimization controller receives a conditional reconfiguration for the CHO from a network and information for attempting conditional reconfiguration upon an RLF. Further, the CHO optimization controller detects whether the RLF has occurred. Further, the CHO optimization controller selects a cell for which a conditional reconfiguration for the CHO is configured when the RLF has occurred. The selection is performed while a timer is active. Further, the CHO optimization controller performs to skip the conditional reconfiguration based on the conditional reconfiguration configured for the CHO for the selected cell; the conditional reconfiguration configured for the CHO is the conditional reconfiguration configured for the CHO with the candidate SCG. Further, the CHO optimization controller performs to initiate a transmission of a RRC reestablishment request (such as NR RRC Reestablishment request) message to the network apparatus. The conditional reconfiguration is not configured for the CHO without the candidate SCG for the selected cell.

[0020] In an embodiment, the timer is an NR timer, which is a T311 timer.

[0021] In an embodiment, the selected cell is a target candidate cell, and the selected cell is the first cell selected after detection of the failure.

[0022] In an embodiment, the CHO optimization controller detects whether a RLF failure or conditions for logging the SHR and a SCG failure have occurred or whether conditions for logging the SPR have occurred. Further, the CHO optimization controller stores SCG information when the RLF failure has occurred, and transmits the stored SCG information to a network apparatus in the wireless network. Further, the CHO optimization controller stores MCG information when the SCG failure is detected, and transmits the SCG information to the network apparatus in the wireless network.

[0023] In an embodiment, the SCG information comprises at least one of the neighbor measurements of the SCG cells, a list of SCG conditions associated with neighbors of the SCG cells, events fulfilled for the candidate SCG and time elapsed between SCG events for neighbors, associated PCells in the same conditional reconfiguration as SCG neighbor cells which are candidate PScells, a time elapsed between the fulfilment of SCG and MCG conditions, whether a PCell condition or a PSCell condition is satisfied for associated PCells or conditional reconfigurations; a first satisfied PSCell event when the PCell event is satisfied first; a time elapsed between the fulfilment of the first fulfilled PCell event and the second satisfied PSCell event when the PCell event is satisfied first.

[0024] In an embodiment, the MCG information comprises neighbor measurements, a list of MCG conditions associated with neighbors, events fulfilled for MCG, a time elapsed between MCG events, associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, a time elapsed between the fulfilment of SCG and MCG conditions, event information, and an order of events.

[0025] 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 preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications can be made within the scope of the embodiments.

[0026]

[0027] According to an example of the present disclosure, by handling CHO with candidate SCGs through conditional reconfiguration, UE can improve performance in dual connectivity scenarios.

[0028]

[0029] These and other features, aspects, and advantages of the present embodiments 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 drawings, in which:

[0030] Figure 1 illustrates a block diagram of a UE implemented to carry out the disclosed subject matter according to the embodiments disclosed herein;

[0031] Figure. 2 illustrates a sequence diagram that illustrates handling an attemptCondConfig with conditional reconfiguration, including CHO with Candidate SCG, according to the embodiments disclosed herein;

[0032] Figure. 3 is a flow chart that illustrates a method for selecting conditional reconfiguration when multiple conditional reconfigurations are configured, according to the embodiments disclosed herein;

[0033] Figure. 4 is a sequence diagram that illustrates a scenario where the UE initiates a RRC reestablishment when all the associated conditional reconfigurations are CHO with candidate SCG(s) according to the embodiments disclosed herein;

[0034] Figure. 5 is a sequence diagram that illustrates a scenario for handling the attemptCondConfig with conditional reconfiguration, including CHO with candidate SCG, according to the embodiments as disclosed herein;

[0035] Figure. 6 is a flow chart that illustrates a method for RLF report or SHR handling when the UE is configured for CHO with Candidate SCG(s), according to the embodiment as disclosed herein;

[0036] Figure. 7 is a flow chart that illustrates a method for SCG failure information reporting when the UE is configured for CHO with candidate SCG(s) according to the embodiments as disclosed herein; and

[0037] Figure. 8 is a flow chart that illustrates a method for handling a CHO with a candidate SCG in a wireless communication network system according to the embodiments as disclosed herein.

[0038] It may be noted that to the extent possible, like reference numerals have been used to represent like elements in the drawing. Further, those of ordinary skill in the art will appreciate that elements in the drawing are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the dimension of some of the elements in the drawing may be exaggerated relative to other elements to help to improve the understanding of aspects of the invention. Furthermore, the elements may have been represented in the drawing by conventional symbols, and the drawings may show only those specific details that are pertinent to the understanding the embodiments of the invention so as not to obscure the drawing with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

[0039]

[0040] 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. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term "or" as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples are not be construed as limiting the scope of the embodiments herein.

[0041] As is traditional in the field, embodiments are described and illustrated in terms of blocks that carry out a described function or functions.　These blocks, which 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 optionally be driven by firmware and software. The circuits, 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 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 be physically separated into two or more interacting and discrete blocks without departing from the scope of the proposed method.　Likewise, the blocks of the embodiments be physically combined into more complex blocks without departing from the scope of the proposed method.

[0042] The accompanying drawings are used to help easily understand various technical features and it is understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the proposed method is construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. used herein to describe various elements, these elements are not be limited by these terms. These terms are generally used to distinguish one element from another.

[0043] Dual connectivity, or more technically, multi-radio dual connectivity, is specified by 3GPP in specifications such as TS 37.340. A summary of the details on dual connectivity is given below. Next-Generation Radio-Access Network (NG-RAN) supports Multi-Radio Dual Connectivity (MR-DC) operation, whereby UE in RRC_CONNECTED is configured to utilize radio resources provided by two distinct schedulers, located in two different NG-RAN nodes connected via a non-ideal backhaul, one providing NR access and the other one providing either Evolved UMTS Terrestrial Radio Access (E-UTRA) or NR access. One node acts as the master node (MN) and the other as the secondary node (SN). The MN and SN are connected via a network interface, and at least the MN is connected to the core network. NG-RAN supports NG-RAN E-UTRA-NR Dual Connectivity (NGEN-DC), in which a UE is connected to one ng-eNB (an E-UTRA base station that can connect to a 5G core) that acts as a MN and one gNB (5G base station) that acts as a SN. NG-RAN also supports NR-E-UTRA Dual Connectivity (NE-DC), in which a UE is connected to one gNB that acts as a MN and one ng-eNB that acts as a SN.

[0044] PSCell change can occur due to mobility and may or may not be associated with the SN change. The SN Change procedure is initiated either by MN or SN and used to transfer a UE context from a source SN to a target SN and to change the SCG configuration in UE from one SN to another. A conditional PSCell Change (CPC) is defined as a PSCell change that is executed by the UE when the execution condition(s) is met. The UE starts evaluating the execution condition(s) upon receiving the CPC configuration and stops evaluating the execution condition(s) once the PSCell change is triggered. Intra-SN CPC without MN involvement and inter-SN CPC initiated either by MN or SN are supported.

[0045] A 5G NR radio access network, also known as the NG-RAN, comprises a number of NR base stations known as gNBs. gNBs can be connected to each other through the Xn interface and will be connected to various core network elements like Access and Mobility Management Function (AMF), User Plane Function (UPF), etc. Further gNBs can be divided into two physical entities named Centralized Unit (CU) and Distributed Unit (DU). CU provides support for the higher layers of the protocol stack, such as Session Data Application Protocol (SDAP), Packet Data Convergence Protocol (PDCP), and Radio Resource Control (RRC), while DU provides support for the lower layers of the protocol stack, such as Radio Link Control (RLC), Medium Access Control (MAC), and the physical layer. Each gNB can have multiple cells serving many UEs. There are a large number of algorithms and configuration parameters used in NG-RAN. Especially, it is a very difficult task to identify the most optimal radio parameters, and operators used to resort to manual techniques like drive tests to identify the parameters. However, such manual parameter tuning is a costly operation since it depends on a lot of factors like the number of users, number of neighbors, maximum throughput in the cell, average throughput in the cell, etc.

[0046] For CHO with candidate SCG(s), the network may also configure the UE with one or more candidate target PCells in the conditional reconfiguration, and each candidate target PCell is associated with one or more candidate PSCells. The UE starts to evaluate the condition of each candidate target PCell and the condition of each associated candidate PSCell upon reception of the conditional reconfiguration. When one of the targets PCells fulfills the associated PCell execution condition and one of its associated candidates PSCells fulfills the associated PSCell execution condition, the UE applies the conditional reconfiguration of the corresponding target PCell and the corresponding candidate PSCell. The network provides the configuration parameters for the target PCell and its associated candidate PSCells in the ConditionalReconfiguration IE or similar such IEs. If there are multiple candidate PSCells associated with one candidate target PCell, the NW can provide multiple conditional configurations for the same candidate target PCell, for example, each one contains one Master Cell Group (MCG) configuration (for the same candidate target PCell) and one SCG configuration (for a different candidate PSCell).

[0047] Embodiments disclosed herein provide a system and method for performing and optimising CHO with candidate SCG(s).

[0048] The current method involves the UE logging and reporting SCG information during radio link failure. This information includes neighbor measurements, a list of SCG conditions associated with neighbors, events fulfilled for SCG and the time elapsed between SCG events for neighbors, associated PCells in the same conditional reconfiguration as SCG neighbor cells, which are candidate PScells, and the time elapsed between the fulfillment of SCG and MCG conditions in the RLF report. Associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, time elapsed between MCG events, neighbor measurements, a list of MCG conditions associated with neighbor and time elapsed between the fulfilment of SCG and MCG conditions are all reported by the UE during SCG failure.

[0049] In the current scenario, where the UE may have multiple candidate configurations for the selected cell, it deals with how the UE chooses a configuration while attempting conditional reconfiguration after RLF.

[0050] The proposed solution provides a method for handling a CHO with a candidate SCG in the wireless network system.

[0051] Figure 1 illustrates a block diagram of a UE (100) implemented to carry out the disclosed subject matter according to the embodiments disclosed herein. As shown, the UE (100) includes a processor (104), a memory (102), and a CHO optimization controller (108). The UE (100) may be an end-user device that connects with a communication network to access services. For example, the UE (100) may include, but is not limited to, a smartphone, personal computer (PC), tablet, personal device assistant (PDA), and the like.

[0052] The processor (104) communicates with the memory, and the CHO optimization controller (108). The processor (104) is configured to implement instructions stored in memory (102) and to perform various methods. The processor (104) can include one or a plurality of processors. It is 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 Artificial Intelligence (AI) dedicated processor such as a neural processing unit (NPU). Further, the memory (102) of the UE (100) includes storage locations to be addressable through the processor (104). The memory (102) is not limited to a volatile memory and / or a non-volatile memory. Further, the memory (102) can include one or more computer-readable storage media. The memory (102) can include non-volatile storage elements. For example, non-volatile storage elements can include magnetic hard discs, optical discs, floppy discs, and flash memories.

[0053] In an embodiment, the CHO optimization controller (108) is innovative hardware that is realized through the physical implementation of both analog and digital circuits, including logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive and active electronic components, as well as optical components.

[0054] In an embodiment, the CHO optimization controller (108), is communicatively coupled to the memory (102) and the processor (104). Further, the CHO optimization controller (108) receives a conditional reconfiguration configuration for the CHO from a network and information for attempting conditional reconfiguration upon an RLF. Further, the CHO optimization controller (108) detects whether the RLF has occurred. Further, the CHO optimization controller (108) selects a cell for which a conditional reconfiguration for the CHO is configured when the RLF has occurred. The selection is performed while a timer is active. Furthermore, the conditional reconfiguration configured for the CHO is the conditional reconfiguration configured for the CHO with the candidate SCG. The CHO optimization controller (108) performs to skip the conditional reconfiguration based on the conditional reconfiguration configured for the CHO for the selected cell. Further, the CHO optimization controller (108) does not perform conditional reconfiguration for the CHO if there is no CHO configuration without the candidate SCG for the chosen cell. Instead, it starts transmitting an RRC reestablishment request message to the network apparatus. The network apparatus is one instance may be the gNB(104).

[0055] In this present invention, ther term attemptCondReconfig may be used in various modified forms. For example, modified terms such as attemptCondReconfig flag or attemptCondConfig may be used. These modified terms all refer to the same concept and may be used interchangeably to aid in the understanding of the present invention.

[0056] Figure 2 illustrates a sequence diagram that illustrates handling an attemptCondConfig with conditional reconfiguration, including CHO with Candidate SCG, according to the embodiments disclosed herein. As shown in the sequence diagram, the UE (100) is in communication with the gNB (104)

[0057] At step S201, the UE (100) is configured with a configuration for CHO with candidate SCG(s) and a flag attemptCondConfig. Handling of attemptCondReconfig flag in the UE (100) when the conditional handover with candidate SCG is configured and / or where conditional handover is configured, and the conditional reconfiguration message includes SCG configuration. attemptCondReconfig flag is described in detail in 3gpp specifications such as NR TS 38.331. The UE (100) applies the stored conditional reconfiguration for the candidate cell excluding the SCG configuration or SCG related configuration (for example, releases SCG configuration from the stored conditional reconfiguration for the candidate cell) while performing the conditional reconfiguration when the selected cell is a target candidate cell and it is the first cell selection after failure; for example, the UE (100) applies only the MCG related configuration from the stored condRRCReconfig associated to the selected cell in this scenario. Failures as referred to herein, may be RLF, radio link failure of the MCG or re-configuration with sync failure of the MCG or mobility from NR failure etc. as described in the background.

[0058] In an embodiment, the UE (100) may exclude SCG cell group configuration, SCG radio bearer configuration, SRB3 configuration and other SCG configurations while applying stored condRRCReconfig associated to the selected cell (i.e., does not apply SCG cell group configuration, SCG radio bearer configuration, SRB3 configuration and other SCG configurations). In an embodiment, the UE (100) may exclude applying the SCG related configuration configured by MCG also (for e.g., in MCG OtherConfig), in the above scenario.

[0059] At step S202, a failure in the MCG is detected. Upon detection of the failure, a candidate cell is selected with associated conditional reconfigurations as CHO with Candidate SCG(s). Release the SCG configuration from the conditional reconfiguration at step S203. Without the completion of the SCG reconfiguration, the RRCReconfigurationComplete message was sent to the gNB (104) at step S204.

[0060] Figure 3 is a flow chart that illustrates a method for selecting conditional reconfiguration when multiple conditional reconfigurations are configured, according to the embodiments disclosed herein.

[0061] In an embodiment, at step 302, multiple conditional reconfigurations are received in one or multiple RRC messages for the same candidate cell Cx. For instance, information on which conditional reconfiguration to be performed for the candidate cell Cx upon cell selection after the failure may be received. MCG failure is followed by cell selection at step 304. The chosen cell, Cx, was chosen as the initial choice following a failure. At step 306, a conditional reconfiguration is performed according to or based on the information received.

[0062] Figure 4 is a sequence diagram that illustrates a scenario, where the UE (100) initiates a RRC Reestablishment when all the associated conditional reconfigurations are CHO with Candidate SCG(s) according to the embodiments disclosed herein;

[0063] In an embodiment, at step S401, the UE (100) is configured with configuration for CHO with Candidate SCG(s) and an attemptCondConfig, and at step S402, failure occurs in MCG and the UE (100) selects a candidate cell where all the associated conditional reconfigurations are CHO with Candidate SCG(s). At step S403, the UE (100) sends a RRC Reestablishment message to the gNB(104).

[0064] Figure 5 is a sequence diagram that illustrates a scenario for handling attemptCondConfig with conditional reconfiguration including CHO with Candidate SCG, according to the embodiments as disclosed herein;

[0065] At step S501, the UE (100) is configured with configuration for CHO with candidate SCG(s) and attemptCondConfig. At step S502, failure occurs in MCG and the UE (100) selects a candidate cell with associated conditional reconfigurations as CHO with Candidate SCG(s). At step S503, the UE (100) keeps the SCG configuration from the conditional reconfiguration. At step S504, the RRCReconfigurationComplete message is sent to gNB (104), including SCG reconfiguration complete without checking SCG criteria.

[0066] Embodiments herein disclose methods and systems for attempting conditional reconfiguration during cell selection after RLF, when CHO Conditional Handover with candidate SCG(s) are configured.

[0067] In an embodiment, a NR UE which is configured for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig, may exclude applying all the configurations configured by IEs such as secondaryCellGroup or mrdc-SecondaryCellGroupConfig while performing the conditional reconfiguration when the selected cell is a target candidate cell and it is the first cell selection after failure. The UE (100) applies the stored conditional reconfiguration for the candidate cell excluding all the configurations configured by IEs such as secondaryCellGroup or mrdc-SecondaryCellGroupConfig in this scenario. Further, at step S204, the UE (100) sends a RRCReconfigurationComplete without including the SCG RRC reconfiguration complete. RRCReconfigurationComplete is sent after applying the stored conditional reconfiguration for the candidate cell (excluding SCG configuration).

[0068] An example specification extract from TS 38.331 is given below:

[0069] 5.3.7.3 Actions following cell selection while T311 is running

[0070] Upon selecting a suitable NR cell, the UE shall:

[0071] 1> if attemptCondReconfig is configured; and

[0072] 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

[0073] 1> if the selected cell is one of the candidate cells for which the reconfigurationWithSync is included in the masterCellGroup in the MCG VarConditionalReconfig:

[0074] 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;

[0075] 2> if the stored condRRCReconfig associated to the selected cell includes condExecutionCondSCG or condExecutionCondPSCell

[0076] 2> release the configurations configured by IEs such as secondaryCellGroup or mrdc-SecondaryCellGroupConfig and SCG radio bearers including SRB3 and SCG DRB / MRB and apply the stored condRRCReconfig associated to the selected cell and perform actions as specified in 5.3.5.3; (i.e., apply the MCG related configuration from the stored condRRCReconfig associated to the selected cell and perform actions as specified in 5.3.5.3)

[0077] 2> else

[0078] 3> apply the stored condRRCReconfig associated to the selected cell and perform actions as specified in 5.3.5.3;

[0079] In an embodiment, at step S203, the release of SCG configuration is applicable only for performing conditional reconfiguration for this cell selection after failure. The UE (100) keeps SCG configuration in the stored conditional reconfiguration, and may perform CHO with candidate SCG(s) later using the same conditional reconfiguration when both CHO and CPA / CPC conditions are satisfied.

[0080] In an alternate embodiment, the network informs the UE (100) which is configured for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig whether to release SCG configuration (i.e., whether to apply SCG configuration) while performing the conditional reconfiguration when the selected cell is a target candidate cell, and it is the first cell selection after failure. This may be informed through a RRC message. In an embodiment, this may be through a flag or an enumerated or an indicator in the conditional reconfiguration configuration or any other IEs such as reconfiguration identifiers or other identifiers and indicator informs that upon the selection of the associated candidate cells, release may be performed (or alternatively flag / enum / id / list tells not to perform release of SCG). Based on the received information from the network, the UE (100) decides whether to apply SCG configuration while performing the conditional reconfiguration when the selected cell is a target candidate cell, and it is the first cell selection after failure and attemptCondReconfig is configured.

[0081] In an alternate embodiment, the UE (100) (which is configured for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig) may apply both MCG and SCG configuration (keep the SCG configuration), while performing the conditional reconfiguration when the selected cell is a target candidate cell and it is the first cell selection after failure. Even though the SCG conditions may not be satisfied, the UE (100) includes the SCG reconfiguration complete (RRCReconfigurationComplete) message in the MCG reconfiguration complete message send to the MN. In an embodiment, the UE (100) may inform the network that the Reconfiguration complete is send due to attemptCondReconfig. Network may further release the SCG configuration. Alternatively, the UE (100) may apply both MCG and SCG configuration (keep the SCG configuration) while performing the conditional reconfiguration when the selected cell is a target candidate cell and it is the first cell selection after failure, but may not include SCG Reconfiguration complete in the MCG Reconfiguration Complete send.

[0082] The UE (100) (which is configured for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig and has performed the conditional reconfiguration when the selected cell is a target candidate cell and it is the first cell selection after failure) may inform the network that it has SCG measurements available (if available). The UE (100) may include an availability indicator in the RRCReconfigurationComplete to inform the network. In an embodiment, a NR UE may include this information in the IE UE -MeasurementsAvailable.

[0083] -- ASN1START

[0084] -- TAG-UE-MeasurementsAvailable-START

[0085]

[0086] UE-MeasurementsAvailable-r16 ::=　　　SEQUENCE {

[0087] logMeasAvailable-r16　　　ENUMERATED {true}　　　OPTIONAL,

[0088] logMeasAvailableBT-r16　　　ENUMERATED {true}　　　OPTIONAL,

[0089] logMeasAvailableWLAN-r16　　　ENUMERATED {true}　　　OPTIONAL,

[0090] connEstFailInfoAvailable-r16　　　ENUMERATED {true}　　　OPTIONAL,

[0091] rlf-InfoAvailable-r16　　　ENUMERATED {true}　　　OPTIONAL,

[0092] ...,

[0093] [[

[0094] successHO-InfoAvailable-r17　　　ENUMERATED {true}　　　OPTIONAL,

[0095] sigLogMeasConfigAvailable-r17　　　BOOLEAN　　　OPTIONAL

[0096] ]]

[0097] [[

[0098] SCGMeasAvailalbeAfterCondReconfig　　　ENUMERATED {true}　　　OPTIONAL

[0099] ]]

[0100] }

[0101] The network may further retrieve these measurements by sending RRC message such as UEInformationRequest; for e.g., by including a flag SCGMeasAfterCondReconfigReq and the UE (100) reports the available SCG measurements in the UEInformationResponse.

[0102] 5.7.10.3 Reception of the UEInformationRequest message:

[0103] Upon receiving the UEInformationRequest message, the UE shall, only after successful security activation:

[0104] 1> If the SCGMeasAfterCondReconfigReq is included in the UEInformationRequest and the UE has SCG measurements available before the failure

[0105] 2> for each serving cell configured with servingCellMO:

[0106] 3> if SSB based serving cell measurements are available:

[0107] 4> set the measResultServingCell within measResultServingMOList to include RSRP, RSRQ and the available SINR of the serving cell, derived based on SSB;

[0108] 3> else if CSI-RS based serving cell measurements are available:

[0109] 4> set the measResultServingCell within measResultServingMOList to include RSRP, RSRQ and the available SINR of the serving cell, derived based on CSI-RS;

[0110] 4> set the servCellId within measResultServingMOList to include each NR serving cell that is configured with servingCellMO, if any;

[0111] 4> set the measResultNeighCellListNR within measResultServFreqListNR-SCG to include one entry with the physCellId and the available measurement quantities based on the reportQuantityCell and rsType indicated in reportConfig of the non-serving cell corresponding to the concerned measObjectNR with the highest measured RSRP if RSRP measurement results are available for cells corresponding to this measObjectNR, otherwise with the highest measured RSRQ if RSRQ measurement results are available for cells corresponding to this measObjectNR, otherwise with the highest measured SINR, where availability is considered according to the measurement configuration associated with the SCG;

[0112] 5> if the reportConfig associated with the measId that triggered the measurement reporting includes reportQuantityRS-Indexes and maxNrofRS-IndexesToReport:

[0113] 6> for each best non-serving cell included in the measurement report:

[0114] 7> include beam measurement information according to the associated reportConfig as described in 5.5.5.2, where availability is considered according to the measurement configuration associated with the SCG;

[0115] In an embodiment, the UE (100) may store the SCG measurements after failure and reports the same upon request by the network through UEInformationRequest. In an embodiment, the UE (100) may store the SCG measurements in the VarMeasIdleReport or VarLogMeasReport. In an embodiment, the UE (100) may store the SCG measurements in a separate UE (100) variable VarSCGMeasReport and report the same upon request from the network through UEInformationRequest.

[0116] In an embodiment, the UE (100) may discard these stored SCG measurements after sending the same to the network, while moving to RRC_IDLE or RRC_INACTIVE or after a specific timer such as 48h from storing the SCG measurements.

[0117] In an embodiment, the UE (100) (which is configured with attemptCondReconfig) may apply only MCG related configuration from the stored conditional reconfiguration (i.e., release the SCG related configuration) while performing the conditional reconfiguration including SCG, irrespective of whether the UE (100) is configured for CHO with candidate SCG(s) when the selected cell is a target candidate cell (i.e., even when the UE (100) is configured for CHO with SCG configuration and without conditions for CPA / CPC, the UE (100) applies only MCG related configuration), and it is the first cell selection after failure.

[0118] In an alternate embodiment, the UE (100) (which is configured for the CHO with candidate SCG(s) and has experienced the failure when the CHO conditions are satisfied, but while waiting for CPA / CPC conditions are fulfilled) performs conditional reconfiguration without performing RRC Reestablishment procedure.

[0119] In an alternate embodiment, the UE (100) (which is configured for the CHO with candidate SCG(s) and is also configured with attemptCondReconfig and has experienced the failure when the CHO conditions are satisfied, but while waiting for CPA / CPC conditions are fulfilled) performs conditional reconfiguration without performing cell selection after failure.

[0120] In an alternate embodiment, the UE (100) (which is configured for the CHO with candidate SCG(s) and has experienced the failure when the CHO conditions are satisfied, but while waiting for CPA / CPC conditions are fulfilled) performs conditional reconfiguration only for MCG (i.e., does not apply SCG configuration) without performing RRC Reestablishment procedure

[0121] In an alternate embodiment, the UE (100) (which is configured for the CHO with candidate SCG(s) and is also configured with attemptCondReconfig and has experienced the failure when the CHO conditions are satisfied, but while waiting for CPA / CPC conditions are fulfilled) performs conditional reconfiguration only for MCG (i.e. doesn't apply SCG configuration) without performing cell selection after failure.

[0122] In an embodiment, when the UE (100) is configured with multiple conditional reconfigurations for the same candidate cell, the network may inform the UE (100) which conditional reconfiguration to be used for performing various embodiments in this invention (and for the behavior in background) after it has experienced the failure.

[0123] In an embodiment, when the UE (100) is configured with multiple conditional reconfigurations for the same candidate cell, network includes an indication about which conditional reconfiguration is to be used for performing conditional reconfiguration after the UE (100) has experienced failure and the UE (100) has selected the same candidate cell and it is the first cell selection after failure. The indication may be conditional reconfiguration identifier to be used. This indication may be a flag or enumerated or any such indication and is included in CondReconfigToAddMod SEQUENCE. In an embodiment, if the UE (100) receives the information about which conditional reconfiguration to be used for performing conditional reconfiguration after the UE (100) has experienced failure and the UE (100) has selected the same candidate cell and it is the first cell selection after failure, the UE (100) perform conditional reconfiguration according to the received information.

[0124] CondReconfigToAddMod-r16 ::=　　　SEQUENCE {

[0125] condReconfigId-r16　　　CondReconfigId-r16,

[0126] condExecutionCond-r16　　　　SEQUENCE (SIZE (1..2)) OF MeasID　　　OPTIONAL,　　　-- Need M

[0127] condRRCReconfig-r16　　　　　　OCTET STRING (CONTAINING RRCReconfiguration)　　　OPTIONAL,　　　-- Cond condReconfigAdd

[0128] ...,

[0129] [[

[0130] condExecutionCondSCG-r17　　　OCTET STRING (CONTAINING CondReconfigExecCondSCG-r17)　　　OPTIONAL　　　-- Need M

[0131] ]] ,

[0132] [[

[0133] condExecutionCondPSCell-r18　　　SEQUENCE (SIZE (1..2)) OF MeasId　　　OPTIONAL　　　-- Need M

[0134] ]]

[0135] [[

[0136] SelectCondReconfig　　　ENUMERATED {true}　　　OPTIONAL,　　　-- Cond CHO

[0137] }

[0138] ConditionalReconfiguration field descriptions:

[0139] selectCondReconfig: If present, the UE shall perform conditional reconfiguration using this condReconfig if selected cell is this target candidate cell and it is the first cell selection after failure as described in clause 5.3.7.3.

[0140]

[0141] 5.3.7.3 Actions following cell selection while T311 is running:

[0142] Upon selecting a suitable NR cell, the UE shall:

[0143] 1> if attemptCondReconfig is configured; and

[0144] 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

[0145] 1> if the selected cell is one of the candidate cells for which the reconfigurationWithSync is included in the masterCellGroup in the MCG VarConditionalReconfig:

[0146] 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;

[0147] 2> if there are multiple condRRReconfig associated to the selected cell

[0148] 3> apply the stored condRRCReconfig with selectCondReconfig associated to the selected cell and perform actions as specified in 5.3.5.3.

[0149] else

[0150] 3> apply the stored condRRCReconfig associated to the selected cell and perform actions as specified in 5.3.5.3

[0151] In an embodiment, if the UE (100) is configured with SelectCondReconfig, the UE (100) may perform the conditional reconfiguration according to the stored condRRCReconfig including selectCondReconfig, associated to the selected cell only if attemptCondReconfig is also configured.

[0152] In an embodiment, if the UE (100) is configured with SelectCondReconfig, the UE (100) may perform the conditional reconfiguration according to the stored condRRCReconfig including selectCondReconfig, associated to the selected cell irrespective of whether attemptCondReconfig is also configured.

[0153] In an embodiment, the UE (100) which is configured for the CHO with candidate SCG(s) and for the CHO without candidate SCG(s) for the same candidate cell C1, and is also configured with attemptCondReconfig, performs the conditional reconfiguration using the conditional reconfiguration configured for CHO without candidate SCG(s), when the selected cell is the target candidate cell C1, and it is the first cell selection after failure. For e.g., the UE (100) is configured with CondReconfig with condReconfigId-r16 x, including one of condExecutionCondSCG or condExecutionCondPSCell and is configured with CondReconfig with condReconfigId-r16 y without any of condExecutionCondSCG or condExecutionCondPSCell for the same candidate cell C2. The UE (100) is also configured with attemptCondReconfig. Upon a failure and initiating RRC Reestablishment procedure and selecting the same cell C2, the UE (100) applies the conditional reconfiguration with condReconfigId-r16 y. Alternatively, the UE (100) may select the conditional reconfiguration with candidate SCG(s) in this case (i.e., select condReconfigId-r16 x).

[0154] The following principles apply to the CPC: The CPC configuration contains the configuration of CPC candidate PSCell(s) and execution condition(s) and may contain the MN configuration for inter-SN CPC. An execution condition may consist of one or two trigger conditions (CPC events A3 / A5, as defined in TS 38.331). Only a single Reference Signal (RS) type is supported, and at most two different trigger quantities (e.g., Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ), RSRP and Signal-to-Interference-plus-Noise Ratio (SINR), etc.) can be configured simultaneously for the evaluation of the CPC execution condition of a single candidate PSCell. Before any CPC execution condition is fulfilled, upon reception of the PSCell change command or the PCell change command, the UE (100) executes the PSCell change procedure as described in clauses 10.3 and 10.5 or the PCell change procedure as described in clause 9.2.3.2 in TS 38.300 or clause 10.1.2.1 in TS 36.300, regardless of any previously received CPC configuration. Upon the successful completion of the PSCell change procedure or PCell change procedure, the UE (100) releases all stored CPC configurations. While executing CPC, the UE (100) is not required to continue evaluating the execution condition of other candidate PSCell(s). Once the CPC procedure is executed successfully, the UE (100) releases all stored CPC configurations. Upon the release of SCG, the UE (100) releases the stored CPC configurations.

[0155] The MN adds PSCell during a PSCell addition procedure. A PSCell addition procedure that is executed only when PSCell addition condition(s) are met is called Conditional PSCell Addition (CPA).

[0156] The UE (100) sends SCGFailureInformation to report SCG failures to MN. The purpose of this procedure is to inform MN about an SCG failure the UE (100) has experienced, for example, SCG radio link failure, failure of SCG reconfiguration with sync, SCG configuration failure for RRC message on SRB3, SCG integrity check failure, and consistent uplink LBT failures on PSCell for operation with shared spectrum channel access.

[0157] The UE (100) behavior during SCGFailure is described in 3GPP specifications. In NR, this is captured in specifications such as TS 38.331 and TS 37.340, as given below.

[0158] According to TS 37.340, in all SCG failure cases,

[0159] the UE maintains the current measurement configurations from both the MN and the SN, and the UE continues measurements based on the configurations from the MN and the SN if possible. The SN measurements configured to be routed via the MN will continue to be reported after the SCG failure.

[0160] NOTE 2: the UE may not continue measurements based on configuration from the SN after SCG failure in certain cases (for example, the UE cannot maintain the timing of PSCell).

[0161] In the case of CPA / CPC, upon transmission of the SCGFailureInformation message to the MN, the UE stops evaluating the CPA / CPC execution condition.

[0162] The UE is not required to continue measurements for candidate PSCell(s) for execution condition upon transmission of the SCGFailureInformation message to the MN.

[0163] According to TS 38.331, upon initiating the procedure, the UE shall:

[0164] 1> if the procedure was not initiated due to beam failure of the PSCell while the SCG is deactivated:

[0165] 2> suspend SCG transmission for all SRBs, DRBs, and, if any, BH RLC channels;

[0166] 2> reset SCG MAC;

[0167] 1> stop T304 for the SCG, if running;

[0168] 1> Stop conditional reconfiguration evaluation for CPC or CPA, if configured;

[0169] 1> if the UE is in (NG)EN-DC:

[0170] 2> initiate transmission of the SCGFailureInformationNR message as specified in TS 36.331

[0010] , clause 5.6.13a.

[0171] In the conventional method, the network cannot configure SCG candidate cells in a CHO configuration. This causes considerable delays for the addition and change of PSCells, which adversely affects the UE (100) performance in dual connectivity scenarios. Hence, 3GPP is introducing CHO, including target MCGs and candidate SCGs, in NR Release 18. CHO, including target MCG and candidate SCGs, is a handover procedure in the NR-DC scenario that is executed only when the execution condition(s) of candidate PCells and the execution condition(s) of PSCells are met. This procedure may also be called CHO with the candidate SCG(s).

[0172] For CHO with candidate SCG(s), the network may also configure the UE (100) with one or more candidate target PCells in the conditional reconfiguration, and each candidate target PCell is associated with one or more candidate PSCells. The UE (100) starts to evaluate the condition of each candidate target PCell and the condition of each associated candidate PSCell upon reception of the conditional reconfiguration. When one of the target PCells fulfils the associated PCell execution condition, and one of its associated candidate PSCells fulfils the associated PSCell execution condition, the UE (100) applies the conditional reconfiguration of the corresponding target PCell and the corresponding candidate PSCell. The network provides the configuration parameters for the target PCell and its associated candidate PSCells in the ConditionalReconfiguration IE. If there are multiple candidate PSCells associated with one candidate target PCell, the NW can provide multiple conditional configurations for the same candidate target PCell, for example, each one contains one MCG configuration (for the same candidate target PCell) and one SCG configuration (for a different candidate PSCell).

[0173] An example specification of the configuration of CHO with candidate SCG(s) based on 3gpp TS 38.331 is given below.

[0174] - CondReconfigToAddModList

[0175]

[0176] The IE CondReconfigToAddModList concerns a list of conditional reconfigurations to add or modify, with for each entry the condReconfigId and the associated condExecutionCond / condExecutionCondSCG / condExecutionCondPSCell and condRRCReconfig.

[0177]

[0178] The IE ConditionalReconfiguration is used to add, modify, and release the configuration of conditional reconfiguration.

[0179] ConditionalReconfiguration information element:

[0180] -- ASN1START

[0181] -- TAG-CONDITIONALRECONFIGURATION-START

[0182]

[0183] ConditionalReconfiguration-r16 ::=　　　SEQUENCE {

[0184] attemptCondReconfig-r16　　　ENUMERATED {true}　　　OPTIONAL,　　　-- Cond CHO

[0185] condReconfigToRemoveList-r16　　　CondReconfigToRemoveList-r16　　　OPTIONAL,　　　-- Need N

[0186] condReconfigToAddModList-r16　　　CondReconfigToAddModList-r16　　　OPTIONAL,　　　-- Need N

[0187] ...

[0188] }

[0189]

[0190] CondReconfigToRemoveList-r16 ::=　　　SEQUENCE (SIZE (1.. maxNrofCondCells-r16)) OF CondReconfigId-r16

[0191]

[0192] -- TAG-CONDITIONALRECONFIGURATION-STOP

[0193] -- ASN1STOP

[0194]

[0195] ConditionalReconfiguration field descriptions:

[0196] attemptCondReconfig: If present, the UE shall perform conditional reconfiguration if the selected cell is a target candidate cell and it is the first cell selection after failure as described in clause 5.3.7.3.

[0197] condReconfigToAddModList: List of the configuration of candidate SpCells to be added or modified for CHO, CPA, or CPC.

[0198] condReconfigToRemoveList: List of the configuration of candidate SpCells to be removed.

[0199] Conditional Presence:

[0200] CHO: The field is optional and present; need R if the UE is configured with at least a candidate SpCell for CHO. Otherwise, the field is not present.

[0201] Performing conditional reconfiguration after failure:

[0202] As mentioned above, if the network includes the attemptCondReconfig flag in the CondtionalReconfiguration field, the UE (100) performs conditional reconfiguration if the selected cell is a target cell and if it is the first cell selection after failure. The details of the UE (100) usage of the flag are usually specified in 3GPP specifications, such as TS 38.331. Below is an example extract from the specification.

[0203] 5.3.7 RRC connection re-establishment

[0204] The purpose of this procedure is to re-establish the RRC connection. The UE in RRC_CONNECTED, for which Access Stratum (AS) security has been activated with Signaling Radio Bearer (SRB)2 and at least one Data Radio Bearer (DRB) / multicast Radio Bearer (MRB) setup or, for Integrated Access and Backhaul (IAB), SRB2, may initiate the procedure in order to continue the RRC connection. The connection re-establishment succeeds if the network is able to find and verify the valid UE context, if the UE context cannot be retrieved, and the network responds with an RRCSetup according to clause 5.3.3.4.

[0205] The network applies the procedure, e.g., as follows:

[0206] - When AS security has been activated and the network retrieves or verifies the UE context:

[0207] - to re-activate AS security without changing algorithms;

[0208] - to re-establish and resume SRB1;

[0209] - When the UE is re-establishing an RRC connection and the network is not able to retrieve or verify the UE context,

[0210] - to discard the stored AS context and release all Radio Bearer (RB)s and Back Haul Radio Link Control (BH RLC) channels and Uu (this is the radio interface between the UE and the evolved NodeB in LTE) Relay RLC channels;

[0211] - to fallback to establish a new RRC connection.

[0212] If AS security has not been activated, the UE shall not initiate the procedure but instead moves to RRC_IDLE directly, with release cause 'other'. If AS security has been activated but SRB2 and at least one DRB or multicast MRB or, for IAB, SRB2, are not setup, the UE does not initiate the procedure but instead moves to RRC_IDLE directly, with the release cause 'RRC connection failure'.

[0213] 5.3.7.2 Initiation

[0214] The UE initiates the procedure when one of the following conditions is met:

[0215] 1> upon detecting radio link failure of the MCG and t316 is not configured, in accordance with 5.3.10; or

[0216] 1> upon detecting radio link failure of the MCG while SCG transmission is suspended, in accordance with 5.3.10; or

[0217] 1> upon detecting radio link failure of the MCG while PSCell change or PSCell addition is ongoing, in accordance with 5.3.10; or

[0218] 1> upon detecting radio link failure of the MCG while the SCG is deactivated, in accordance with 5.3.10; or

[0219] 1> upon re-configuration with sync failure of the MCG, in accordance with clause 5.3.5.8.3; or

[0220] 1> upon mobility from NR failure, in accordance with clause 5.4.3.5; or

[0221] 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

[0222] 1> upon an RRC connection reconfiguration failure, in accordance with clause 5.3.5.8.2; or

[0223] 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

[0224] 1> upon reconfiguration with sync failure of the SCG while MCG transmission is suspended in accordance with clause 5.3.5.8.3; or

[0225] 1> upon SCG change failure while MCG transmission is suspended in accordance with TS 36.331

[0010] clause 5.3.5.7a; or

[0226] 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

[0227] 1> upon integrity check failure indication from SCG lower layers concerning SRB3 while MCG is suspended; or

[0228] 1> upon T316 expiry, in accordance with clause 5.7.3b.5; or

[0229] 1> upon detecting sidelink radio link failure by L2 U2N Remote UE in RRC_CONNECTED, in accordance with clause 5.8.9.3; or

[0230] 1> upon reception of NotificationMessageSidelink, including indicationType, by L2 U2N Remote UE in RRC_CONNECTED, in accordance with clause 5.8.9.10; or

[0231] 1> upon PC5 unicast link release indicated by upper layer at L2 U2N Remote UE in RRC_CONNECTED.

[0232] NOTE 0: It is up to the UE implementation whether to initiate the procedure while T346g is running.

[0233] Upon initiation of the procedure, the UE shall:

[0234] 1> stop timer T310, if running;

[0235] 1> stop timer T312, if running;

[0236] 1> stop timer T304, if running;

[0237] 1> start timer T311;

[0238] 1> stop timer T316, if running;

[0239] 1> if UE is not configured with attemptCondReconfig:

[0240] 2> reset MAC;

[0241] 2> release spCellConfig, if configured;

[0242] 2> suspend all RBs, BH RLC channels for IAB-MT, and Uu Relay RLC channels for L2 U2N Relay UE, except SRB0 and broadcast MRBs;

[0243] 2> release the MCG SCell(s), if configured;

[0244] 2> if MR-DC is configured:

[0245] 3> perform MR-DC release, as specified in clause 5.3.5.10;

[0246] 2> release delayBudgetReportingConfig, if configured and stop timer T342, if running;

[0247] 2> release overheatingAssistanceConfig, if configured, and stop timer T345, if running;

[0248] 2> release idc-AssistanceConfig, if configured;

[0249] 2> release btNameList, if configured;

[0250] 2> release wlanNameList, if configured;

[0251] 2> release sensorNameList, if configured;

[0252] 2> release drx-PreferenceConfig for the MCG, if configured, and stop timer T346a associated with the MCG, if running;

[0253] 2> release maxBW-PreferenceConfig for the MCG, if configured, and stop timer T346b associated with the MCG, if running;

[0254] 2> release maxCC-PreferenceConfig for the MCG, if configured, and stop timer T346c associated with the MCG, if running;

[0255] 2> release maxMIMO-LayerPreferenceConfig for the MCG, if configured and stop timer T346d associated with the MCG, if running;

[0256] 2> release minSchedulingOffsetPreferenceConfig for the MCG, if configured, stop timer T346e associated with the MCG, if running;

[0257] 2> release rlm-RelaxationReportingConfig for the MCG, if configured, and stop timer T346j associated with the MCG, if running;

[0258] 2> release bfd-RelaxationReportingConfig for the MCG, if configured, and stop timer T346k associated with the MCG, if running;

[0259] 2> release releasePreferenceConfig, if configured stop timer T346f, if running;

[0260] 2> release onDemandSIB-Request if configured, and stop timer T350, if running;

[0261] 2> release referenceTimePreferenceReporting, if configured;

[0262] 2> release sl-AssistanceConfigNR, if configured;

[0263] 2> release obtainCommonLocation, if configured;

[0264] 2> release musim-GapAssistanceConfig, if configured and stop timer T346h, if running;

[0265] 2> release musim-LeaveAssistanceConfig, if configured;

[0266] 2> release ul-GapFR2-PreferenceConfig, if configured;

[0267] 2> release scg-DeactivationPreferenceConfig, if configured, and stop timer T346i, if running;

[0268] 2> release propDelayDiffReportConfig, if configured;

[0269] 2> release rrm-MeasRelaxationReportingConfig, if configured;

[0270] 2> release maxBW-PreferenceConfigFR2-2, if configured;

[0271] 2> release maxMIMO-LayerPreferenceConfigFR2-2, if configured;

[0272] 2> release minSchedulingOffsetPreferenceConfigExt, if configured;

[0273] 1> release successHO-Config, if configured;

[0274] 1> if any Dual Active Protocol Stack (DAPS) bearer is configured:

[0275] 2> reset the source MAC and release the source MAC configuration;

[0276] 2> for each DAPS bearer:

[0277] 3> release the RLC entity or entities as specified in TS 38.322 [4], clause 5.1.3, and the associated logical channel for the source SpCell;

[0278] 3> reconfigure the Packet Data Convergence Protocol (PDCP) entity to release DAPS as specified in TS 38.323 [5];

[0279] 2> for each SRB:

[0280] 3> release the PDCP entity for the source SpCell;

[0281] 3> release the RLC entity as specified in TS 38.322 [4], clause 5.1.3, and the associated logical channel for the source SpCell;

[0282] 2> release the physical channel configuration for the source SpCell;

[0283] 2> discard the keys used in the source SpCell (the KgNB key, the KRRCenc key, the KRRCint key, the KUPint key and the KUPenc key), if any;

[0284] 1> release sl-L2RelayUE-Config, if configured;

[0285] 1> release sl-L2RemoteUE-Config, if configured;

[0286] 1> release the SRAP entity, if configured;

[0287] 1> if the UE is acting as L2 U2N Remote UE:

[0288] 2> if the PC5-RRC connection with the U2N Relay UE is determined to be released:

[0289] 3> indicate upper layers to trigger PC5 unicast link release;

[0290] 3> perform either cell selection in accordance with the cell selection process as specified in TS 38.304

[0020] , or relay selection as specified in clause 5.8.15.3, or both;

[0291] 2> else (i.e., maintain the PC5 RRC connection):

[0292] 3> consider the connected L2 U2N Relay UE as suitable and perform actions as specified in clause 5.3.7.3a;

[0293] NOTE 1: It is up to Remote UE implementation whether to release or keep the current PC5 unicast link.

[0294] 1> else:

[0295] 2> if the UE is capable of L2 U2N Remote UE:

[0296] 3> perform either cell selection as specified in TS 38.304

[0020] , or relay selection as specified in clause 5.8.15.3, or both;

[0297] 2> else:

[0298] 3> perform cell selection in accordance with the cell selection process as specified in TS 38.304

[0020] .

[0299] NOTE 2: For L2 U2N Remote UE, if both a suitable cell and a suitable relay are available, the UE can select either one based on its implementation.

[0300] 5.3.7.3 Actions following cell selection while T311 is running:

[0301] Upon selecting a suitable NR cell, the UE shall:

[0302] 1> ensure having valid and up to date essential system information as specified in clause 5.2.2.2;

[0303] 1> stop timer T311;

[0304] 1> if T390 is running:

[0305] 2> stop timer T390 for all access categories;

[0306] 2> perform the actions as specified in 5.3.14.4;

[0307] 1> stop the relay (re)selection procedure, if ongoing;

[0308] 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

[0309] 1> if attemptCondReconfig is configured; and

[0310] 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

[0311] 1> if the selected cell is one of the candidate cells for which the reconfigurationWithSync is included in the masterCellGroup in the MCG VarConditionalReconfig:

[0312] 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;

[0313] 2> apply the stored condRRCReconfig associated to the selected cell and perform actions as specified in 5.3.5.3;

[0314] 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.

[0315] 1> else:

[0316] 2> if UE is configured with attemptCondReconfig:

[0317] 3> reset MAC;

[0318] 3> release spCellConfig, if configured;

[0319] 3> release the MCG SCell(s), if configured;

[0320] 3> release delayBudgetReportingConfig, if configured and stop timer T342, if running;

[0321] 3> release overheatingAssistanceConfig , if configured and stop timer T345, if running;

[0322] 3> if MR-DC is configured:

[0323] 4> perform MR-DC release, as specified in clause 5.3.5.10;

[0324] 3> release idc-AssistanceConfig, if configured;

[0325] 3> release btNameList, if configured;

[0326] 3> release wlanNameList, if configured;

[0327] 3> release sensorNameList, if configured;

[0328] 3> release drx-PreferenceConfig for the MCG, if configured and stop timer T346a associated with the MCG, if running;

[0329] 3> release maxBW-PreferenceConfig for the MCG, if configured and stop timer T346b associated with the MCG, if running;

[0330] 3> release maxCC-PreferenceConfig for the MCG, if configured and stop timer T346c associated with the MCG, if running;

[0331] 3> release maxMIMO-LayerPreferenceConfig for the MCG, if configured and stop timer T346d associated with the MCG, if running;

[0332] 3> release minSchedulingOffsetPreferenceConfig for the MCG, if configured and stop timer T346e associated with the MCG, if running;

[0333] 3> release rlm-RelaxationReportingConfig for the MCG, if configured and stop timer T346j associated with the MCG, if running;

[0334] 3> release bfd-RelaxationReportingConfig for the MCG, if configured and stop timer T346k associated with the MCG, if running;

[0335] 3> release releasePreferenceConfig, if configured and stop timer T346f, if running;

[0336] 3> release onDemandSIB-Request if configured, and stop timer T350, if running;

[0337] 3> release referenceTimePreferenceReporting, if configured;

[0338] 3> release sl-AssistanceConfigNR, if configured;

[0339] 3> release obtainCommonLocation, if configured;

[0340] 3> release scg-DeactivationPreferenceConfig, if configured, and stop timer T346i, if running;

[0341] 3> release musim-GapAssistanceConfig, if configured and stop timer T346h, if running;

[0342] 3> release musim-LeaveAssistanceConfig, if configured;

[0343] 3> release propDelayDiffReportConfig, if configured;

[0344] 3> release ul-GapFR2-PreferenceConfig, if configured;

[0345] 3> release rrm-MeasRelaxationReportingConfig, if configured;

[0346] 3> release maxBW-PreferenceConfigFR2-2, if configured;

[0347] 3> release maxMIMO-LayerPreferenceConfigFR2-2, if configured;

[0348] 3> release minSchedulingOffsetPreferenceConfigExt, if configured;

[0349] 3> suspend all RBs, and BH RLC channels for the IAB-MT, except SRB0 and broadcast MRBs;

[0350] 2> remove all the entries within the MCG VarConditionalReconfig, if any;

[0351] 2> for each measId, if the associated reportConfig has a reportType set to condTriggerConfig:

[0352] 3> for the associated reportConfigId:

[0353] 4> remove the entry with the matching reportConfigId from the reportConfigList within the VarMeasConfig;

[0354] 3> if the associated measObjectId is only associated to a reportConfig with reportType set to condTriggerConfig:

[0355] 4> remove the entry with the matching measObjectId from the measObjectList within the VarMeasConfig;

[0356] 3> remove the entry with the matching measId from the measIdList within the VarMeasConfig;

[0357] 2> release the PC5 RLC entity for SL-RLC0, if any;

[0358] 2> start timer T301;

[0359] 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;

[0360] 2> apply the default MAC Cell Group configuration as specified in 9.2.2;

[0361] 2> apply the CCCH configuration as specified in 9.1.1.2;

[0362] 2> apply the timeAlignmentTimerCommon included in SIB1;

[0363] 2> initiate transmission of the RRCReestablishmentRequest message in accordance with 5.3.7.4;

[0364] NOTE 2: This procedure applies also if the UE returns to the source PCell.

[0365] Upon selecting an inter-RAT cell, the UE shall:

[0366] 1> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause 'RRC connection failure'.

[0367] In an embodiment, the UE which is configured for the CHO with candidate SCG(s) for a candidate cell C1, and is also configured with attemptCondReconfig, avoids performing the conditional reconfiguration using the conditional reconfiguration configured for CHO with candidate SCG(s), even when the selected cell is the target candidate cell C1, and it is the first cell selection after failure. In this embodiment, in this case, if there is no CHO without candidate SCG(s) configured for C1, the UE initiates transmission of the RRCReestablishmentRequest without performing the conditional reconfiguration using the conditional reconfiguration configured for CHO without candidate SCG(s).

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

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

[0370] 1> ensure having valid and up to date essential system information as specified in clause 5.2.2.2;

[0371] 1> stop timer T311;

[0372] 1> if T390 is running:

[0373] 2> stop timer T390 for all access categories;

[0374] 2> perform the actions as specified in 5.3.14.4;

[0375] 1> stop the relay (re)selection procedure, if ongoing;

[0376] 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

[0377] 1> if attemptCondReconfig is configured; and

[0378] 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

[0379] 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

[0380] 1> if there is at least one conditional reconfiguration not containing condExecutionCondSCG-r17 or condExecutionCondPSCell-r18associated with the selected cell

[0381] 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;

[0382] 2> apply the stored condRRCReconfig in the conditional reconfiguration not containing condExecutionCondSCG-r17 or condExecutionCondPSCell-r18, associated to the selected cell and perform actions as specified in 5.3.5.3;

[0383] 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.

[0384] 1> else:

[0385] 2> if UE is configured with attemptCondReconfig:

[0386] 3> reset MAC;

[0387] 3> release spCellConfig, if configured;

[0388] 3> release the MCG SCell(s), if configured;

[0389] 3> release delayBudgetReportingConfig, if configured and stop timer T342, if running;

[0390] 3> release overheatingAssistanceConfig , if configured and stop timer T345, if running;

[0391] 3> if MR-DC is configured:

[0392] 4> perform MR-DC release, as specified in clause 5.3.5.10;

[0393] 3> release idc-AssistanceConfig, if configured;

[0394] 3> release btNameList, if configured;

[0395] 3> release wlanNameList, if configured;

[0396] 3> release sensorNameList, if configured;

[0397] 3> release drx-PreferenceConfig for the MCG, if configured and stop timer T346a associated with the MCG, if running;

[0398] 3> release maxBW-PreferenceConfig for the MCG, if configured and stop timer T346b associated with the MCG, if running;

[0399] 3> release maxCC-PreferenceConfig for the MCG, if configured and stop timer T346c associated with the MCG, if running;

[0400] 3> release maxMIMO-LayerPreferenceConfig for the MCG, if configured and stop timer T346d associated with the MCG, if running;

[0401] 3> release minSchedulingOffsetPreferenceConfig for the MCG, if configured and stop timer T346e associated with the MCG, if running;

[0402] 3> release rlm-RelaxationReportingConfig for the MCG, if configured and stop timer T346j associated with the MCG, if running;

[0403] 3> release bfd-RelaxationReportingConfig for the MCG, if configured and stop timer T346k associated with the MCG, if running;

[0404] 3> release releasePreferenceConfig, if configured and stop timer T346f, if running;

[0405] 3> release onDemandSIB-Request if configured, and stop timer T350, if running;

[0406] 3> release referenceTimePreferenceReporting, if configured;

[0407] 3> release sl-AssistanceConfigNR, if configured;

[0408] 3> release obtainCommonLocation, if configured;

[0409] 3> release scg-DeactivationPreferenceConfig, if configured, and stop timer T346i, if running;

[0410] 3> release musim-GapAssistanceConfig, if configured and stop timer T346h, if running;

[0411] 3> release musim-LeaveAssistanceConfig, if configured;

[0412] 3> release propDelayDiffReportConfig, if configured;

[0413] 3> release ul-GapFR2-PreferenceConfig, if configured;

[0414] 3> release rrm-MeasRelaxationReportingConfig, if configured;

[0415] 3> release maxBW-PreferenceConfigFR2-2, if configured;

[0416] 3> release maxMIMO-LayerPreferenceConfigFR2-2, if configured;

[0417] 3> release minSchedulingOffsetPreferenceConfigExt, if configured;

[0418] 3> suspend all RBs, and BH RLC channels for the IAB-MT, except SRB0 and broadcast MRBs;

[0419] 2> remove all the entries within the MCG VarConditionalReconfig, if any;

[0420] 2> for each measId, if the associated reportConfig has a reportType set to condTriggerConfig:

[0421] 3> for the associated reportConfigId:

[0422] 4> remove the entry with the matching reportConfigId from the reportConfigList within the VarMeasConfig;

[0423] 3> if the associated measObjectId is only associated to a reportConfig with reportType set to condTriggerConfig:

[0424] 4> remove the entry with the matching measObjectId from the measObjectList within the VarMeasConfig;

[0425] 3> remove the entry with the matching measId from the measIdList within the VarMeasConfig;

[0426] 2> release the PC5 RLC entity for SL-RLC0, if any;

[0427] 2> start timer T301;

[0428] 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;

[0429] 2> apply the default MAC Cell Group configuration as specified in 9.2.2;

[0430] 2> apply the CCCH configuration as specified in 9.1.1.2;

[0431] 2> apply the timeAlignmentTimerCommon included in SIB1;

[0432] 2> initiate transmission of the RRCReestablishmentRequest message in accordance with 5.3.7.4;

[0433] NOTE 2: This procedure applies also if the UE returns to the source PCell.

[0434] Upon selecting an inter-RAT cell, the UE shall:

[0435] 1> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause 'RRC connection failure'.

[0436] AttemptCondReconfig, as disclosed herein, can also be applicable for any other flag or any other way by which the UE (100) is informed by the network to perform conditional reconfiguration after a failure such as RLF or handover failure or Inter-RAT HO failure or any such failure. Similarly, the conditions in this invention such as "if selected cell is a target candidate cell and it is the first cell selection after failure" for attempting to perform conditional reconfiguration is exemplary and are non-limiting. There may be additional conditions added or this condition may not be mandatory.

[0437] Figure 6 is a flow chart that illustrates a method for RLF report or SHR handling when the UE is configured for CHO with Candidate SCG(s), according to the embodiment as disclosed herein

[0438] At step 602, the UE is configured for the CHO, and there is information for attempting a conditional reconfiguration with the candidate SCG(s). At step 604, the UE detects whether the RLF occurred. At step 606, the UE logs and reports the SCG information including neighbor measurement of the SCG cells, a list of SCG conditions associated to neighbors of the SCG cells, events fulfilled for SCG and time elapsed between SCG events for neighbors, associated Pcells in the same conditional reconfiguration as SCG neighbor cells which are candidate Pscells, time elapsed between fulfilment of SCG and MCG conditions in the RLF report, whether a a PCell condition or a PSCell condition is satisfied for associated PCells or conditional reconfigurations, a first satisfied PSCell event when PCell event is satisfied first, a time elapsed between the fulfilment of the first fulfilled PCell event and second satisfied PSCell event when PCell event is satisfied first. The MCG information comprises neighbor measurements, a list of MCG conditions associated with neighbors, events fulfilled for MCG, a time elapsed between MCG events, associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, a time elapsed between the fulfilment of SCG and MCG conditions in SCG failure information, event information, and an order of events.

[0439] The SCG information includes at least one of the following: neighbor measurements of the SCG cells, a list of SCG conditions associated with the neighbors of the SCG cells, events fulfilled for the candidate SCG, the time elapsed between SCG events for neighbors, associated PCells in the same conditional reconfiguration as SCG neighbor cells that are candidate PSCells, the time elapsed between the fulfillment of SCG and MCG conditions, and whether a PCell condition or a PSCell condition is satisfied for associated PCells or conditional reconfigurations.

[0440] A first satisfied PSCell event occurs when the PCell event is satisfied first, followed by the time elapsed between the fulfillment of the initial PCell event and the subsequent satisfied PSCell event.

[0441] Figure 7 is a flow chart that illustrates a method for SCG failure information reporting when the UE is configured for CHO with candidate SCG(s) according to the embodiments as disclosed herein

[0442] At step 702, the UE (1000) is configured with CHO with Candidate SCG(s). At step 704, it is detected whether a SCG failure has occurred. At step 706, the MCG information is reported. For instance, the MCG information includes neighbor measurements, a list of MCG conditions associated with neighbors, events fulfilled for MCG, a time elapsed between MCG events, associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, a time elapsed between the fulfilment of SCG, MCG conditions in SCGFailureInformation, and the like. The UE also may also log the MCG information in SPR when there is no failure, but conditions for SPR are fulfilled.

[0443] The SCG information comprises at least one of neighbor measurements of the SCG cells, a list of SCG conditions associated to neighbors of the SCG cells, events fulfilled for the candidate SCG and the time elapsed between SCG events for neighbors, associated PCells in same conditional reconfiguration as SCG neighbor cells which are candidate PSCells, a time elapsed between fulfilment of SCG and MCG conditions, whether a PCell condition or a PSCell condition is satisfied for associated PCells or conditional reconfigurations, a first satisfied PSCell event when PCell event is satisfied first, a time elapsed between the fulfilment of the first fulfilled PCell event and second satisfied PSCell event when PCell event is satisfied first.

[0444] The MCG information comprises neighbor measurements, a list of MCG conditions associated to neighbors, events fulfilled for MCG, a time elapsed between MCG events, associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, a time elapsed between fulfilment of SCG and MCG conditions, event information and an order of events.

[0445] In an embodiment, the UE, which is configured for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) while performing the conditional reconfiguration when the selected cell is a target candidate cell and it is the first cell selection after failure. In an embodiment, the UE, which has applied the stored conditional reconfiguration for CHO with candidate SCG(s) after failure, and when the selected cell is a target candidate cell and it is the first cell selection after failure, suspends SCG transmission.

[0446] In an embodiment, the UE, which has applied the stored conditional reconfiguration for CHO with candidate SCG(s) after failure, and when the selected cell is a target candidate cell and it is the first cell selection after failure, deactivates SCG(s). In an embodiment, the UE, which has applied the stored conditional reconfiguration for CHO with candidate SCG(s) after failure, and when the selected cell is a target candidate cell and it is the first cell selection after failure, suspends transmission on SCG bearers.

[0447] In an embodiment, the UE, which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG with the highest measurements while performing the conditional reconfiguration when the selected cell (PCell) is a target candidate cell and it is the first cell selection after failure. In an embodiment, the UE, which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG with strongest RSRP measurements while performing the conditional reconfiguration when the selected cell (PCell) is a target candidate cell and it is the first cell selection after failure.

[0448] In an embodiment, the UE which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s), and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG with strongest RSRQ measurements while performing the conditional reconfiguration when the selected cell (PCell) is a target candidate cell and it is the first cell selection after failure.

[0449] In an embodiment, the UE which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s), and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG with strongest SINR measurements while performing the conditional reconfiguration when the selected cell (PCell) is a target candidate cell and it is the first cell selection after failure.

[0450] In an embodiment, the UE, which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG with the highest number of beams above a threshold while performing the conditional reconfiguration when the selected cell (PCell) is a target candidate cell and it is the first cell selection after failure.

[0451] In an embodiment, the UE, which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s) and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG if the latest SCG measurements are above a threshold provided by the network. In an embodiment, these thresholds are the cell selection thresholds. In an embodiment, this threshold is provided by the network node in an RRC message such as an RRC reconfiguration message or an RRC resume message.

[0452] In an embodiment, the UE, which is configured for multiple conditional reconfigurations for the CHO with candidate SCG(s) for the same PCell and which is also configured with attemptCondReconfig, applies the stored conditional reconfiguration for the candidate cell with the SCG configuration(s) corresponding to the SCG, which is closer to fulfilling the SCG criteria, while performing the conditional reconfiguration when the selected cell (PCell) is a target candidate cell and it is the first cell selection after failure. For example, if SCG1 in conditional reconfiguration with id = 1 requires x dBm to satisfy criteria and SCG2 in conditional reconfiguration with id = 2 requires y dBm to satisfy criteria, the UE selects conditional reconfiguration with id = 1 if x > y, otherwise, UE selects conditional reconfiguration with id = 2.

[0453] In an embodiment, the gNB allocates different transaction identifiers for each conditional reconfiguration which it configures for the UE for multiple conditional reconfigurations for the CHO with candidate SCG(s) for the same PCell. Upon performing conditional reconfiguration for the CHO with candidate SCG(s), the UE includes the same transaction identifier in the RRCReconfigurationComplete message, and the target RAN node (MN) identifies the mapped conditional reconfiguration identifier based on the transaction identifier.

[0454] In an embodiment, the UE may inform the network whether it is capable of supporting RLF-Report for conditional handover with candidate SCG(s). In NR, this may be reported using NR RRC message such as the UE Capability Information send from the UE to gNB.

[0455] In an embodiment, the gNB configures the UE to report RLF-report for conditional handover with candidate SCG(s). In an embodiment, in NR, this may be reported using OtherConfig IE in RRCReconfiguration message.

[0456] In an embodiment, the UE (100), which is configured for performing CHO with candidate SCG(s), logs and reports the following information in the RLF report: SCG measurements for the SCG neighbors, where the measurements are configured by either MN or SN. The UE also includes whether those SCG neighbor cells are candidate SCG cells and the candidate PCell or candidate PCells to which each of those neighbor cells which are a candidate PSCell is associated, one or more conditional reconfiguration identifiers to which the neighbor cell which is a candidate PSCell is associated, a list of PSCell events that are satisfied for each of the PCells / conditional reconfigurations and the PSCell event that is satisfied first, and the elapsed time between those PSCell events, whether PCell condition or PSCell condition is satisfied for each of the associated PCells / conditional reconfigurations.

[0457] Similarly, for each of the associated PCells / conditional reconfigurations, the UE also reports the time elapsed between the fulfilment of the first satisfied PCell event and first satisfied PSCell event when PCell event is satisfied first or the time elapsed between the fulfilment of the first fulfilled PCell event and second satisfied PSCell event when PCell event is satisfied first and the time elapsed between the fulfilment of the first satisfied PSCell event and first satisfied PCell event when PSCell event is satisfied first or the time elapsed between the fulfilment of the first fulfilled PSCell event and second satisfied PS / Cell event when PSCell event is satisfied first in the RLF report.

[0458] In an embodiment, the UE logs and reports this information in a successful handover report (SHR) when the SHR conditions are satisfied. As the UE logs the following in SHR: SCG measurements for the SCG neighbors, where the measurements are configured by either MN or SN. The UE also includes whether those SCG neighbor cells are candidate SCG cells and the candidate PCell or candidate PCells to which each of those neighbor cells which are a candidate PSCell is associated, one or more conditional reconfiguration identifiers to which the neighbor cell which is a candidate PSCell is associated, a list of PSCell events that are satisfied for each of the PCells / conditional reconfigurations and the PSCell event that is satisfied first, and the elapsed time between those PSCell events, whether PCell condition or PSCell condition is satisfied for each of the associated PCells / conditional reconfigurations. Similarly, for each of the associated PCells or conditional reconfigurations, the UE also reports the time elapsed between the fulfilment of the first satisfied PCell event and the first satisfied PSCell event when the PCell event is satisfied first, or the time elapsed between the fulfilment of the first fulfilled PCell event and the second satisfied PSCell event when the PCell event is satisfied first, or the time elapsed between the fulfilment of the first satisfied PSCell event and the second satisfied PSCell event when the PSCell event is satisfied first.

[0459] In an embodiment, the UE, which is configured for performing CHO with candidate SCG(s) logs and reports the SCG measurements in the RLF-report. In an embodiment the SCG measurements logged and reported are the measurements configured for CPA / CPC within the configuration for CHO with candidate SCG(s) in the RLF-report. This includes cell identifier for SCG and the RSRP, RSRQ and SINR measurements, if configured. The UE also logs and reports whether the neighbor cells for which measurements are reported are candidate cells. For each of the SCG cell for which the measurements are reported, the UE also logs and reports the SCG execution conditions. For e.g. a NR UE configured for performing CHO with candidate SCG(s) logs and reports the following in RLF-Report: the execution condition for each measurement identifier in condExecutionCondSCG or condExecutionCondPSCell associated to the neighbor cell within conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCondSCG or condExecutionCondPSCell, at the moment of radio link failure or handover failure, the UE logs and reports which among the fulfilled condition of SCG is the first fulfilled condition of SCG in RLF-Report.

[0460] In an embodiment, for each of the SCG PScell for which the measurements are reported, the UE also logs one or more conditional reconfiguration identifier(s) associated to the PSCell. For each of those conditional reconfigurations, the UE also logs and reports the SCG execution conditions. For example, a NR UE configured for performing CHO with candidate SCG(s) logs and reports the following in RLF-Report for each conditional reconfiguration identifier: the execution condition for each measurement identifier in condExecutionCondSCG or condExecutionCondPSCell associated to the neighbor cell within conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCondSCG or condExecutionCondPSCell, at the moment of radio link failure or handover failure, UE logs and reports which among the fulfilled condition of SCG is the first fulfilled condition of SCG in RLF-Report.

[0461] In an embodiment, for each of the SCG PSCell for which the measurements are reported, the UE also logs one or more PCells associated to the PSCell (PCell which is the candidate cell in the same conditional reconfiguration for CHO with candidate SCG(s)). For each of those PCells, the UE also logs and reports the SCG execution conditions. For e.g. a NR UE configured for performing CHO with candidate SCG(s) logs and reports the following in RLF-Report for each PCell which is the candidate cell in the sane conditional reconfiguration for CHO with candidate SCG(s): the execution condition for each measurement identifier in condExecutionCondSCG or condExecutionCondPSCell associated to the neighbor cell within conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCondSCG or condExecutionCondPSCell, at the moment of radio link failure or handover failure, the UE logs and reports which among the fulfilled condition of SCG is the first fulfilled condition of SCG in RLF-Report.

[0462] The UE may also report whether CHO condition or CPAC condition is first fulfilled for the conditional reconfiguration, if both CHO and CPAC conditions are fulfilled. The UE may also log and report the time elapsed between the fulfilments of conditions for CHO (if any condition is fulfilled) within the same conditional reconfiguration and the conditions for PSCell (if any condition is fulfilled). This may be the time elapsed between the fulfilment of first fulfilled PCell condition and the first fulfilled PSCell condition (for e.g. when PCell condition is fulfilled first). Alternatively, this may be the time elapsed between the fulfilment of first fulfilled PSCell condition and the first fulfilled PCell condition (for e.g. when PSCell condition is fulfilled first).

[0463] The UE may report the time elapsed between the fulfilment of first fulfilled PCell condition and the second fulfilled PSCell condition. The UE may report the time elapsed between the fulfilment of second fulfilled PCell condition and the first fulfilled PSCell condition. In an embodiment, the UE may report the time elapsed between the fulfilment of second fulfilled PCell condition and the second fulfilled PSCell condition (for e.g. all the above may bewhen PCell condition is fulfilled first).

[0464] Alternatively, the UE may report the time elapsed between the fulfilment of first fulfilled PSCell condition and the second fulfilled PCell condition. The UE may report the time elapsed between the fulfilment of second fulfilled PSCell condition and the first fulfilled PCell condition. In an embodiment, the UE may report the time elapsed between the fulfilment of second fulfilled PSCell condition and the second fulfilled PCell condition. (For e.g. all the above may be when PSCell condition is fulfilled first).

[0465] In an embodiment the SCG measurements logged and reported in the RLF report when the UE is configured for performing CHO with candidate SCG(s) includes the measurements for all the neighbor cells (i.e. not only the SCG candidate cells configured for CHO with candidate SCG(s)).

[0466] In an embodiment, MN retrieves the SCG related information in the RLF report and SPR and forward the same to SN. SN optimizes the criteria for CPAC in the CHO with conditional SCG(s) and other mobility parameters using the received information.

[0467] In an embodiment, the UE may inform the network whether it is capable of supporting enhancements in SCGFailureInformation for conditional handover with candidate SCG(s). In NR, this may be reported using NR RRC message such as the UE Capability Information send from UE to gNB.

[0468] In an embodiment, the RAN node such as gNB configures the UE to include enhancements for conditional handover with candidate SCG(s) in the SCGFailureInformation. In an embodiment, in NR, this may be send using OtherConfig Information Element (IE) in RRCReconfiguration message.

[0469] In an embodiment, the UE which is configured for performing CHO with candidate SCG(s) reports the following information in the SCGFailureInformation: measurements of the MCG neighbors (neighbor cells of PCell), where the measurements are configured by the MN. The UE also includes whether those MCG neighbor cells (neighbor cells of PCell) are candidate MCG cells and the candidate PSCell or candidate PSCells to which each of those neighbor MCG cells which are candidate PCells is associated, one or more conditional reconfiguration identifiers to which the neighbor PCell which is a candidate PCell is associated, list of PCell events that are satisfied for each of the PSCells / conditional reconfiugrations and the PCell event which is satisfied first and the elapsed time between those PCell events, whether PCell condition or PSCell condition is satisfied for each of the associated PSCells / conditional reconfigurations. Similarly, for each of the associated PSCells / conditional reconfigurations, the UE also reports the time elapsed between the fulfilment of the first satisfied PCell event and first satisfied PSCell event when PCell event is satisfied first or the time elapsed between the fulfilment of the first fulfilled PCell event and second satisfied PSCell event when PCell event is satisfied first and the time elapsed between the fulfilment of the first satisfied PSCell event and first satisfied PCell event when PSCell event is satisfied first or the time elapsed between the fulfilment of the first fulfilled PSCell event and second satisfied PS / Cell event when PSCell event is satisfied first.

[0470] In an embodiment, the UE (100), which is configured for performing CHO with candidate SCG(s), reports the MCG measurements in the SCGFailureInformation message. In an embodiment, the MCG measurements reported in the SCGFailureInformation are the measurements configured for CHO within the configuration for CHO with candidate SCG(s). This includes the cell identifier (Cell Global Identity (CGI) or Physical Cell Identifier (PCI)+Absolute Radio Frequency Channel Number (ARFCN)) for MCG and the RSRP, RSRQ, and SINR measurements, if configured PCI and ARFCN may be reported if CGI is not available. For each of the MCG cells for which the measurements are reported, the UE also logs and reports the MCG execution conditions. For example, a NR UE configured for performing CHO with candidate SCG(s) logs and reports the following in RLF-Report: the execution condition for each measurement identifier in condExecutionCond associated to the neighbor MCG cell within the conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCond, at the moment of SCG failure, the UE logs and reports which among the fulfilled condition of MCG is the first fulfilled condition of MCG in the SCGFailureInformation message.

[0471] In an embodiment, for each of the MCG PCell for which the measurements are reported, the UE reports one or more conditional reconfiguration identifier(s) associated to the PCell. For each of those conditional reconfigurations, the UE reports the MCG execution conditions. For example, the UE configured for performing CHO with candidate SCG(s) logs and reports the following in RLF-Report for each conditional reconfiguration identifier: the execution condition for each measurement identifier in condExecutionCond associated to the neighbor cell within conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCond, at the moment of radio link failure or handover failure, the UE reports which among the fulfilled condition of MCG is the first fulfilled condition of MCG in SCGFailureInformation message.

[0472] In an embodiment, for each of the SCG PS cells for which the measurements are reported in SCGFailureInformation, the UE also reports one or more PCells associated with the PSCell (the PCell which is the candidate cell in the same conditional reconfiguration for CHO with the candidate SCG(s)). For each of those PCells, the UE also reports the MCG execution conditions. For example, the UE configured for performing CHO with candidate SCG(s) logs and reports the following in SCGFailureInformation for each PCell, which is the candidate cell in the sane conditional reconfiguration for CHO with candidate SCG(s): the execution condition for each measurement identifier in condExecutionCond associated with the neighbor cell within conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCond at the moment of radio link failure or handover failure, the UE logs and reports which among the fulfilled condition of MCG is the first fulfilled condition of MCG in SCGFailureInformation.

[0473] In an embodiment, the UE may log the above information in the SPR when the conditions for reporting the SPR are satisfied. For each of the SCG PScells for which the measurements are reported in SPR, the UE also reports one or more PCells associated with the PSCell (PCell, which is the candidate cell in the same conditional reconfiguration for CHO with candidate SCG(s)). For each of those PCells, the UE also reports the MCG execution conditions. For e.g. a NR UE configured for performing CHO with candidate SCG(s) logs and reports the following in SPR for each PCell, which is the candidate cell in the sane conditional reconfiguration for CHO with candidate SCG(s): the execution condition for each measurement identifier in condExecutionCond associated with the neighbor cell within the conditional reconfiguration configuration. If there is at least one fulfilled condition in the logged condExecutionCond,at the moment of radio link failure or handover failure, the UE logs and reports which among the fulfilled condition of MCG is the first fulfilled conditions of MCG in SPR.

[0474] In an embodiment, for each of the MCG PCells for which the measurements are reported in SCGFailureInformation, the UE also logs one or more PSCells associated with the PCell (PSCell, which is the candidate cell in the same conditional reconfiguration for CHO with candidate SCG(s)). For each of those PSCells, the UE also reports the MCG execution conditions of the associated PCell. For e.g. a NR UE configured for performing CHO with candidate SCG(s) logs and reports the following in SCGFailureInformation for each PCell, which is the candidate cell in the sane conditional reconfiguration for CHO with candidate SCG(s): the execution condition for each measurement identifier in condExecutionCond associated with the neighbor cell within the conditional reconfiguration configuration. If there is at least one fulfilled condition in the reported condExecutionCond, at the moment of radio link failure or handover failure, the UE reports that among the fulfilled conditions of MCG, this is the first fulfilled condition of MCG in SCGFailureInformation.

[0475] The UE may also report whether the CHO condition or CPAC condition is first fulfilled for the conditional reconfiguration if both CHO and CPAC conditions are fulfilled. The UE may also log and report the time elapsed between the fulfilment of conditions for CHO (if any condition is fulfilled) within the same conditional reconfiguration and the conditions for PSCell (if any condition is fulfilled). This may be the time elapsed between the fulfilment of the first fulfilled PCell condition and the first fulfilled PSCell condition (for example, when PCell condition is fulfilled first). Alternatively, this may be the time elapsed between the fulfilment of the first fulfilled PSCell condition and the first fulfilled PCell condition (for example, when the PSCell condition is fulfilled first).

[0476] The UE may report the time elapsed between the fulfilment of the first fulfilled PCell condition and the second fulfilled PSCell condition. UE may report the time elapsed between the fulfilment of the second fulfilled PCell condition and the first fulfilled PSCell condition. In an embodiment, the UE may report the time elapsed between the fulfilment of the second fulfilled PCell condition and the second fulfilled PSCell condition (for example, all the above may be when the PCell condition is fulfilled first).

[0477] Alternatively, the UE may report the time elapsed between the fulfilment of the first fulfilled PSCell condition and the second fulfilled PCell condition. The UE may report the time elapsed between the fulfilment of the second fulfilled PSCell condition and the first fulfilled PCell condition. In an embodiment, the UE may report the time elapsed between the fulfilment of the second fulfilled PSCell condition and the second fulfilled PCell condition. (For example, all the above may be true when the PSCell condition is fulfilled first.).

[0478] In an embodiment, the MCG measurements reported in the SCGFailureInformation when the UE is configured for performing CHO with candidate SCG(s) include the measurements for all the neighbor cells (such as. not only the MCG candidate cells configured for CHO with candidate SCG(s)). In an embodiment, SN retrieves the MCG-related information in the SCGFailureInformation and SPR and forwards the same to MN. MN optimizes the criteria for CHO in the CHO with conditional SCG(s) and other mobility parameters using the received information.

[0479] Figure 8 is a flow chart that illustrates a method for handling a CHO with a candidate SCG in the wireless communication network system, according to the embodiments as disclosed herein; The flow chart includes steps (802-810). Each step is explained in further detail below.

[0480] In step 802, a conditional reconfiguration configuration for the CHO and an information for attempting a conditional reconfiguration upon a RLF is received by the UE.

[0481] In step 804, the UE detects whether the RLF has occurred. The UE performs storing SCG information when the RLF failure or conditions for logging of SHR have occurred and transmitting the stored SCG information to a network apparatus in the wireless network and storing MCG information when the SCG failure or conditions for logging of SPR are detected, and transmitting the SCG information to the network apparatus in the wireless network. The SCG information comprises at least one of neighbor measurements of the SCG cells, a list of SCG conditions associated to neighbors of the SCG cells, events fulfilled for the candidate SCG and the time elapsed between SCG events for neighbors, associated PCells in same conditional reconfiguration as SCG neighbor cells which are candidate PSCells, a time elapsed between fulfilment of SCG and MCG conditions, whether a PCell condition or a PSCell condition is satisfied for associated PCells or conditional reconfigurations, a first satisfied PSCell event when PCell event is satisfied first, a time elapsed between the fulfilment of the first fulfilled PCell event and second satisfied PSCell event when PCell event is satisfied first. Here are the are the measurements of neighbors for the SCG cells.

[0482] In an embodiment, the MCG information comprises neighbor measurements, a list of MCG conditions associated to neighbors, events fulfilled for MCG, a time elapsed between MCG events, associated PSCells in the same conditional reconfiguration as MCG neighbor candidate cells, a time elapsed between fulfilment of SCG and MCG conditions, event information and an order of events.

[0483] In step 806, selecting a cell configured for conditional reconfiguration of the CHO when an RLF occurs, with the selection taking place while a timer is running. The selected cell is a target candidate cell, and the selected cell is a first cell selection after the detection of failure. The timer is the NR T311 timer.

[0484] In step 808, performing either skipping the conditional reconfiguration based on the configuration for the CHO for the chosen cell, where the conditional reconfiguration for the CHO aligns with that configured for CHO with the candidate SCG candidates.

[0485] In step 810, initiating the transmission of an RRC reestablishment request message to the network apparatus, where the conditional reconfiguration is not set for the CHO without the candidate SCG for the selected cell.

[0486] The various actions, acts, blocks, steps, or the like in the method is performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some of the actions, acts, blocks, steps, or the like are omitted, added, modified, skipped, or the like without departing from the scope of the proposed method.

[0487] 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 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 preferred 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:detecting a radio link failure (RLF) for a serving cell of a base station;selecting a target cell for initiating a radio resource control (RRC) connection re-establishment based on the RLF being detected;identifying whether the target cell is included in at least one candidate cell of a master cell group (MCG) for conditional handover (CHO) and information associated with a secondary cell group (SCG) for CHO is configured for a corresponding conditional reconfiguration identity (ID) of the target cell, based on information for attempting a conditional reconfiguration included in conditional reconfiguration information; andapplying the conditional reconfiguration associated with the target cell, in case that the target cell is included in at least one candidate cell of the MCG for CHO and the information associated with the SCG for CHO is not configured for the corresponding conditional reconfiguration ID of the target cell.2.The method of claim 1, further comprising:receiving, from the base station, an RRC reconfiguration message including the conditional reconfiguration information,wherein the conditional reconfiguration information includes the conditional reconfiguration associated with the target cell and the corresponding reconfiguration ID of the target cell.3.The method of claim 1,wherein a timer is started upon initiating the RRC connection re-establishment, andthe target cell is selected while the timer is running.4.The method of claim 1,wherein the target cell is a first cell selected by the terminal after the RLF.5.The method of claim 1,wherein the information associated with the SCG for CHO includes information for an execution condition to be fulfilled for associated PSCell.6.The method of claim 1, further comprising:skipping the conditional reconfiguration associated with the target cell, in case that the information associated with the SCG for CHO is configured for the corresponding conditional reconfiguration ID of the target cell.7.The method of claim 1, further comprising:initiating a transmission of an RRC message used to request the reestablishment of an RRC connection to network, in case that the target cell is not included in the at least one candidate cell for CHO.8.A terminal in a wireless communication system, the terminal comprising:a transceiver; anda processor, configured to:detect a radio link failure (RLF) for a serving cell of a base station;select a target cell for initiating a radio resource control (RRC) connection re-establishment based on the RLF being detected;identify whether the target cell is included in at least one candidate cell of a master cell group (MCG) for conditional handover (CHO) and information associated with a secondary cell group (SCG) for CHO is configured for a corresponding conditional reconfiguration identity (ID) of the target cell, based on information for attempting a conditional reconfiguration included in conditional reconfiguration information; andapply the conditional reconfiguration associated with the target cell, in case that the target cell is included in at least one candidate cell of the MCG for CHO and the information associated with the SCG for CHO is not configured for the corresponding conditional reconfiguration ID of the target cell.9.The terminal of claim 8,wherein the processor is further configured to receive from the base station, an RRC reconfiguration message including the conditional reconfiguration information, andwherein the conditional reconfiguration information includes the conditional reconfiguration associated with the target cell and the corresponding reconfiguration ID of the target cell.10.The terminal of claim 8,wherein a timer is started upon initiating the RRC connection re-establishment, andthe target cell is selected while the timer is running.11.The terminal of claim 8,wherein the target cell is a first cell selected by the terminal after the RLF.12.The terminal of claim 8,wherein the information associated with the SCG for CHO includes information for an execution condition to be fulfilled for associated PSCell.13.The terminal of claim 8,wherein the processor is further configured to skip the conditional reconfiguration associated with the target cell, in case that the information associated with the SCG for CHO is configured for the corresponding conditional reconfiguration ID of the target cell.14.The terminal of claim 8,wherein the processor is further configured to initiate a transmission of an RRC message used to request the reestablishment of an RRC connection to network, in case that the target cell is not included in the at least one candidate cell for CHO.

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