Method and apparatus for CHO with candidate SCG for CPC / CPA procedure

Abstract

Embodiments of the present application relate to methods and apparatus for conditional handover (CHO) for a candidate secondary cell group (SCG) with a conditional primary secondary cell group cell (PSCell) change (CPC) / conditional PSCell addition (CPA) procedure. In accordance with an embodiment of the present application, a user equipment (UE) includes a transceiver and a processor coupled to the transceiver; and the processor is configured to cause the UE to: receive radio resource control (RRC) configuration information for a CHO having a candidate secondary cell group (SCG) for a conditional primary secondary cell group cell (PSCell) change (CPC) / conditional PSCell addition (CPA) procedure; and accessing a candidate PCell based on the RRC configuration information.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication technology, and more particularly to methods and apparatus for conditional handover (CHO) of a candidate secondary cell group (SCG) with a conditional primary secondary cell group cell (PSCell) change (CPC) / conditional PSCell add (CPA) procedure. Background Art

[0002] In a multi-radio dual connectivity (MR-DC) scenario, a UE with multiple transceivers can be configured to utilize resources provided by two different nodes connected via a non-ideal backhaul. One of the nodes can provide New Radio (NR) access and the other can provide Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) (E-UTRA) or NR access. One node can act as a master node (MN) and the other can act as a secondary node (SN). The MN and SN are connected via a network interface (for example, an Xn interface or an X2 interface as specified in the 3rd Generation Partnership Project (3GPP) standard documents), and at least the MN is connected to the core network.

[0003] Currently, the conditional PSCell addition (CPA) procedure and the conditional PSCell change (CPC) procedure are supported. The CPAC procedure can be a CPA procedure or a CPC procedure. According to the agreement of the 3GPP standard document, the CPAC procedure is defined as the PSCell addition or PSCell change performed by the UE when the configured CPAC execution conditions are met or satisfied. After receiving the CPAC-related configuration information, the UE immediately starts to evaluate the CPAC execution conditions, and once the PSCell addition and / or change procedure is triggered or executed, the UE stops evaluating the CPAC execution conditions. Triggering or executing the PSCell addition and / or change procedure means that when the CPAC execution conditions of the candidate PSCell are met or satisfied ("candidate PSCell" can also be referred to as "CPAC candidate PSCell"), the UE determines the candidate PSCell as the target PSCell and executes the PSCell addition or change procedure for the target PSCell, for example, the UE performs a RA procedure on the target PSCell.

[0004] A CHO having a candidate SCG for a CPC / CPA procedure may also be referred to as a "CHO having a candidate SCG procedure", or a "CHO comprising a target MCG and a candidate SCG for a CPC / CPA procedure", or a "CHO comprising a target MCG and a candidate SCG for a CPA / CPC procedure", or a "CHO with a candidate SCG procedure", or a "CHO comprising a target MCG and a candidate SCG procedure", or a "CHO comprising a candidate target MCG and a candidate target SCG for a CPC / CPA procedure", or a "CHO comprising a candidate target MCG and a candidate target SCG procedure", etc.

[0005] In a CHO with a candidate SCG for a CPC / CPA procedure, when the UE receives a configuration for a CHO including a target MCG and a candidate SCG for a CPC / CPA procedure (i.e., a CHO configuration involving or including a CPC or CPA configuration, or a configuration for a CHO with a candidate SCG procedure), for example, when the UE receives a configuration for a CHO candidate (target) PCell, a CHO execution condition, a configuration for a CPAC candidate (target) PSCell, and a CPAC execution condition, CHO evaluation and CPC or CPA evaluation may be performed simultaneously. For example, the UE starts evaluating the CHO execution condition for the candidate (target) PCell and the CPAC execution condition for the candidate (target) PSCell (when receiving the configuration for the CHO with the candidate SCG procedure) at the same time. The UE does not perform CPC or CPA unless the CHO execution condition for the CHO candidate PCell is met.

[0006] Currently, details on the MRO mechanism for simultaneously performing PCell / PSCell changes and for a CHO with a candidate SCG for CPC / CPA procedures (ie, a CHO with a candidate SCG procedure) have not been discussed. Summary of the Invention

[0007] Some embodiments of the present application provide a user equipment (UE). The UE includes a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to cause the UE to: receive first radio resource control (RRC) configuration information for a candidate secondary cell group (SCG) having a conditional primary secondary cell group (PSCell) change (CPC) / conditional PSCell add (CPA) procedure; and access a candidate PCell based on the first RRC configuration information.

[0008] In some embodiments, the first RRC configuration information includes: a first CHO configuration related to a candidate primary cell (PCell); a first CHO execution condition for the candidate PCell; configuration information for one or more candidate SCGs associated with one or more candidate PSCells; and a set of execution conditions for the one or more candidate SCGs.

[0009] In some embodiments, the processor is configured to cause the UE to receive second RRC configuration information for a second CHO configuration without a candidate SCG.

[0010] In some embodiments, a second CHO execution condition is configured for the second CHO configuration.

[0011] In some embodiments, the second RRC configuration information includes a first indication indicating an association relationship between the second CHO configuration and the first CHO configuration.

[0012] In some embodiments, in response to receiving the first indication, the processor is configured to cause the UE to consider that a second CHO execution condition for the second CHO configuration is the same as the first CHO execution condition for the candidate PCell.

[0013] In some embodiments, in response to satisfying both the second CHO execution condition for the second CHO configuration and the first CHO execution condition for the first CHO configuration, the processor is configured to cause the UE to: in response to satisfying the set of execution conditions for one candidate SCG within the one or more candidate SCGs, perform CHO on the candidate PCell and a candidate PSCell associated with the one candidate SCG based on the first CHO configuration; or in response to not satisfying the set of execution conditions for the one or more candidate SCGs, perform CHO on the candidate PCell based on the second CHO configuration.

[0014] In some embodiments, the processor is configured to cause the UE to receive: a second indication indicating that CHO is allowed to be performed by the UE based on a second CHO configuration without a candidate SCG; or a third indication indicating that the second CHO configuration without a candidate SCG associated with the candidate PCell is the same as the first CHO configuration associated with the candidate PCell.

[0015] In some embodiments, in response to receiving the second indication or the third indication, the processor is configured to cause the UE to consider the second CHO configuration to be the same as the first CHO configuration.

[0016] In some embodiments, in response to the set of execution conditions for the one or more candidate SCGs not being met and the first CHO execution condition being met, the processor is configured to cause the UE to access the candidate PCell based on the second CHO configuration.

[0017] In some embodiments, after successfully accessing the candidate PCell based on the second CHO configuration, the processor is configured to cause the UE to: release one or more SCG bearers configured in the one or more candidate SCGs; or remap the one or more SCG bearers to a master cell group (MCG) bearer configured in the candidate PCell.

[0018] In some embodiments, the processor is configured to cause the UE to: perform CHO based on the first CHO configuration or the second CHO configuration; and after successfully accessing the candidate PCell, transmit an RRC reconfiguration complete message to the candidate PCell.

[0019] In some embodiments, the RRC reconfiguration complete message includes an indication indicating which one of the first CHO configuration and the second CHO configuration the UE has performed CHO based on.

[0020] In some embodiments, the RRC reconfiguration complete message includes at least one of: an identifier (ID) of the candidate PCell accessed by the UE; or an ID of a candidate PSCell accessed by the UE.

[0021] In some embodiments, in response to a trigger condition being met, the processor is configured to cause the UE to transmit both a successful handover report (SHR) and a successful PSCell change report (SPCR) to a target network node.

[0022] In some embodiments, the processor is configured to cause the UE to receive a threshold value related to the trigger condition from a source network node, and wherein the threshold value is: a first threshold value associated with a timer for initiating failure recovery based on a triggered measurement report; or a second threshold value associated with a physical layer problem timer; or a third threshold value associated with a handover timer.

[0023] In some embodiments, the threshold is a percentage of the timer length.

[0024] In some embodiments, the trigger condition includes at least one of the following: the elapsed duration of the timer for initiating fault recovery based on a triggered measurement report exceeds the first threshold multiplied by the length of the timer for initiating fault recovery based on a triggered measurement report; the elapsed duration of the physical layer problem timer exceeds the second threshold multiplied by the length of the physical layer problem timer; or the elapsed duration of the switching timer exceeds the third threshold multiplied by the length of the switching timer.

[0025] In some embodiments, the SHR and SPCR are included in the UE Information Response message.

[0026] In some embodiments, in response to a set of execution conditions of multiple SCGs within the one or more candidate SCGs being met, the UE information response message further includes ID information of other SCGs within the multiple SCGs except for the SCG accessed by the UE.

[0027] Some embodiments of the present application provide a source network node, comprising: a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to cause the source network node to: transmit a handover request for CHO; and receive a response from a candidate network node, wherein the response includes: a first CHO configuration associated with a candidate primary cell (PCell); and configuration information for one or more candidate SCGs associated with one or more candidate PSCells.

[0028] In some embodiments, the response includes a set of execution conditions for the one or more candidate SCGs.

[0029] In some embodiments, the processor is configured to cause the source network node to receive an indication from the candidate network node, wherein the indication indicates that a second CHO configuration associated with the candidate PCell is the same as a first CHO configuration associated with the candidate PCell.

[0030] In some embodiments, the indication is included in a handover request confirm message.

[0031] In some embodiments, the processor is configured to cause the source network node to transmit the indication to the UE.

[0032] In some embodiments, the processor is configured to cause the source network node to transmit a threshold value related to a triggering condition to a user equipment (UE), and wherein the triggering condition is used to trigger simultaneous transmission of both a successful handover report (SHR) and a successful PSCell change report (SPCR).

[0033] In some embodiments, the threshold is a percentage of the timer length.

[0034] In some embodiments, the threshold is: a first threshold associated with a timer for initiating fault recovery based on triggering a measurement report; or a second threshold associated with a physical layer problem timer; or a third threshold associated with a handover timer.

[0035] In some embodiments, the trigger condition includes at least one of the following: the elapsed duration of the timer for initiating fault recovery based on a triggered measurement report exceeds the first threshold multiplied by the length of the timer for initiating fault recovery based on a triggered measurement report; the elapsed duration of the physical layer problem timer exceeds the second threshold multiplied by the length of the physical layer problem timer; or the elapsed duration of the switching timer exceeds the third threshold multiplied by the length of the switching timer.

[0036] Some embodiments of the present application provide a candidate network node, comprising: a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to cause the candidate network node to: receive a handover request for CHO from a source network node; and transmit a response to the source network node, wherein the response comprises: a first CHO configuration related to a candidate primary cell (PCell); and configuration information for one or more candidate SCGs associated with one or more candidate PSCells.

[0037] In some embodiments, the response includes a set of execution conditions for the one or more candidate SCGs.

[0038] In some embodiments, the processor is configured to cause the candidate network node to transmit an indication to the source network node, and wherein the indication indicates that a second CHO configuration associated with the candidate PCell is the same as a first CHO configuration associated with the candidate PCell.

[0039] In some embodiments, the processor is configured to cause the candidate network node to receive both a successful handover report (SHR) and a successful PSCell change report (SPCR) from a user equipment (UE), and wherein the SHR and the SPCR are transmitted simultaneously by the UE in response to satisfaction of a triggering condition.

[0040] In some embodiments, the trigger condition includes at least one of the following: the elapsed duration of the timer for initiating fault recovery based on a triggered measurement report exceeds a first threshold multiplied by the length of the timer for initiating fault recovery based on a triggered measurement report; the elapsed duration of the physical layer problem timer exceeds a second threshold multiplied by the length of the physical layer problem timer; or the elapsed duration of the switching timer exceeds a third threshold multiplied by the length of the switching timer.

[0041] In some embodiments, each of the first threshold, the second threshold, and the third threshold is a percentage value of a timer length.

[0042] In some embodiments, the SHR and SPCR are included in the UE Information Response message.

[0043] In some embodiments, in response to satisfying the set of execution conditions for multiple SCGs within the one or more candidate SCGs, the UE information response message further includes identifier (ID) information of other SCGs within the multiple SCGs except for the SCG accessed by the UE.

[0044] Some embodiments of the present application provide a method executable by a user equipment (UE), comprising: receiving first radio resource control (RRC) configuration information for a candidate secondary cell group (SCG) having a conditional primary secondary cell group (PSCell) change (CPC) / conditional PSCell add (CPA) procedure; and accessing the candidate PCell based on the first RRC configuration information.

[0045] Some embodiments of the present application provide a method that can be performed by a source network node, the method comprising: transmitting a handover request for CHO; and receiving a response from a candidate network node, wherein the response comprises: a first CHO configuration associated with a candidate primary cell (PCell); and configuration information for one or more candidate SCGs associated with one or more candidate PSCells.

[0046] Some embodiments of the present application provide a method that can be performed by a candidate network node. The method includes: receiving a handover request for CHO from a source network node; and transmitting a response to the source network node, wherein the response includes: a first CHO configuration related to a candidate primary cell (PCell); and configuration information for one or more candidate SCGs associated with one or more candidate PSCells.

[0047] Some embodiments of the present application also provide an apparatus for wireless communication. The apparatus includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement any of the above methods performed by a UE, a source network node, or a candidate network node.

[0048] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the present application and therefore should not be considered to limit its scope.

[0050] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application is illustrated.

[0051] Figure 2 Illustrated is an exemplary UE information procedure according to some embodiments of the present application.

[0052] Figure 3 An exemplary flow diagram illustrating accessing a candidate PCell according to some embodiments of the present application is illustrated.

[0053] Figure 4 An exemplary flow diagram illustrating transmission of a handover request according to some embodiments of the present application is illustrated.

[0054] Figure 5 An exemplary flow diagram illustrating receiving a handover request according to some embodiments of the present application is illustrated.

[0055] Figures 6 to 8 Illustrated is an exemplary flow chart related to CHO with candidate SCG procedures according to some embodiments of the present application.

[0056] Figure 9 Illustrated is an exemplary block diagram of an apparatus according to some embodiments of the present application. DETAILED DESCRIPTION

[0057] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments, which are intended to be included in the spirit and scope of the present application.

[0058] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, the embodiments are provided in the context of specific network architectures and new service scenarios, such as 3GPP 5G and 3GPP LTE Release 8. Please note that as network architectures and new service scenarios evolve, all embodiments in this application are also applicable to similar technical problems; and further, the terms described in this application may change, which should not affect the principles of this application.

[0059] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application is illustrated.

[0060] like Figure 1 As illustrated and shown in FIG, a wireless communication system 100 includes at least one UE 101 and at least one BS 102. Specifically, for illustrative purposes, the wireless communication system 100 includes one UE 101 (e.g., UE 101a) and three BSs 102 (e.g., BS 102a, BS 102b, and BS 102c). Figure 1 A specific number of UEs 101 and BSs 102 are depicted in FIG. 1 , but please consider that any number of UEs 101 and BSs 102 may be included in the wireless communication system 100 .

[0061] UE 101 may include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), an in-vehicle computer, a network device (e.g., a router, a switch, and a modem), an Internet of Things (IoT) device, etc. According to some embodiments of the present application, UE 101 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of transmitting and receiving communication signals on a wireless network. In some embodiments of the present application, UE 101 includes a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, etc. In addition, UE 101 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or may be described using other terms used in the art. UE 101 may communicate directly with BS 102 via an uplink (UL) communication signal.

[0062] In some embodiments of the present application, each of UE 101 may be deployed with an IoT application, an eMBB application, and / or a URLLC application. Please note that the specific type of application deployed in UE 101 may vary and is not limited.

[0063] BSs 102 may be distributed across a geographic area. In certain embodiments of the present application, each of BSs 102 may also be referred to as an access point, access terminal, base, base unit, macrocell, Node B, evolved Node B (eNB), gNB, NG-RAN (Next Generation Radio Access Network) node, Home Node B, relay node, or device, or described using other terms used in the art. BSs 102 are typically part of a radio access network, which may include one or more controllers communicatively coupled to one or more corresponding BSs 102.

[0064] The wireless communication system 100 may be compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with wireless communication networks, cellular telephone networks, time division multiple access (TDMA)-based networks, code division multiple access (CDMA)-based networks, orthogonal frequency division multiple access (OFDMA)-based networks, LTE networks, 3GPP-based networks, 3GPP 5G networks, satellite communication networks, high altitude platform networks, and / or other communication networks.

[0065] In some embodiments of the present application, the wireless communication system 100 is compatible with the 5G of the 3GPP protocol, wherein the BS 102 transmits data using an OFDM modulation scheme on the downlink (DL) and the UE 101 transmits data using a single carrier frequency division multiple access (SC-FDMA) or OFDM scheme on the UL. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0066] In some embodiments of the present application, BS 102 may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Furthermore, in some embodiments of the present application, BS 102 may communicate via licensed spectrum, while in other embodiments, BS 102 may communicate via unlicensed spectrum. The present application is not intended to be limited to any particular wireless communication system architecture or protocol implementation. In still other embodiments of the present application, BS 102 may communicate with UE 101 using 3GPP 5G protocols.

[0067] Each BS 102 may include one or more cells. Each UE 101 may perform a cell segment procedure between different cells of different BSs. Each UE 101 may switch from a serving cell of a source BS to a target cell of a target BS. For example, in Figure 1 In the wireless communication system 100 illustrated and shown in FIG, BS 102a may serve as a source BS, and each of BS 102b and BS 102c may serve as a target BS. Figure 1 UE 101a illustrated and shown in FIG may perform a handover procedure from a serving cell of BS 102a to a target cell of BS 102b or a target cell of BS 102c, depending on the result of the cell selection procedure. The handover procedure performed by UE 101a may be a CHO procedure.

[0068] As specified in the 3GPP standard documents, CHO is defined as a handover performed by a user equipment (UE) when one or more CHO execution conditions are met. Upon receiving CHO-related configuration information (e.g., including one or more configurations associated with a candidate PCell and one or more CHO execution conditions), the UE immediately starts evaluating the one or more CHO execution conditions, and stops evaluating the CHO execution conditions during CHO execution or once one or more CHO execution conditions are met. CHO execution means that when the CHO execution conditions of a candidate PCell are met or satisfied ("candidate PCell" may also be referred to as "CHO candidate PCell"), the UE determines the candidate PCell as the target PCell and performs a PCell change or handover procedure for the target PCell, such as the UE performing an RA procedure on the target PCell.

[0069] Mobility Robustness Optimization (MRO) detects connectivity failures caused by premature or late handovers, or handovers to the wrong cell. The general procedure is that after an RLF / HO failure occurs, the UE accesses a new cell through reestablishment or connection establishment. Once the UE enters the Connected state, it transmits an RLF report and a RACH report to the serving cell. The serving cell then transmits a failure indication including the RLF report to the last serving cell. This information is then used to optimize mobility. One of the functions of Mobility Robustness Optimization is to detect connectivity failures caused by premature or late handovers, or handovers to the wrong cell.

[0070] Generally speaking, in the UE information procedure, after an RLF or HO failure occurs, the UE may perform an RRC reestablishment procedure in the cell. The UE will store some information related to the RLF failure and / or HO failure. The UE stores the latest RLF report, including both LTE and NRRLF reports, until the RLF report is retrieved by the network or 48 hours after the connection failure is detected. To analyze the connection failure, the UE makes the RLF report available to the network.

[0071] Figure 2 Illustrated is an exemplary UE information procedure according to some embodiments of the present application. Figure 2 The embodiment of FIG. 1 shows a procedure for a UE (eg, UE 210) to communicate with a BS (eg, BS 220). In some examples, UE 210 may be used as Figure 1 UE 101a in. BS 220 can be used as Figure 1 BS102a, BS102b or BS102c in.

[0072] like Figure 2 As shown in FIG. 2 , in operation 201, BS 220 (e.g., Figure 1 1 and 2. The BS 102a illustrated and shown in FIG. 1 may provide a UE 210 (e.g., Figure 1 UE 101a) transmits a UE Information Request message. BS 220 may be a source BS that controls a serving cell of UE 210. In operation 202, BS 210 transmits a UE Information Response message including an RLF report to BS 220. BS 220 may optimize mobility issues based on the response transmitted from UE 210.

[0073] In 3GPP Rel-17, a Successful Handover Report (SHR) was introduced for MRO of the PCell change procedure. The PCell change can be a legacy PCell change or handover or a conditional PCell change or conditional handover (CHO). In particular, the MRO functionality in NR can be enhanced to provide more robust mobility by reporting failure events observed during a successful handover from the source NG-RAN to the target NG-RAN by SHR. SHR is a report associated with a successful handover, which includes a set of measurements collected during the handover phase, i.e., measurements at the time of handover triggering, measurements at the end of handover execution, or measurements after handover execution. For example, when at least one of the following triggering conditions is met and / or the RA for the PCell is successful, the UE may store information related to the successful PCell change or generate a VarSuccessHO-Report / SHR:

[0074] (1) The ratio between the value of the elapsed time of timer T310 of the source PCell and the configured value of timer T310 configured for the source PCell when the UE was connected to the source PCell before performing the last PCell change / HO procedure is greater than a configured threshold (e.g., thresholdPercentageT310 configured by the source PCell before performing the last PCell change / HO procedure).

[0075] (2) If T312 associated with the measurement identifier of the target PCell is running when the PCell change / HO procedure is initiated, and if the ratio between the value of the elapsed time of timer T312 and the configured value of timer T312 (configured when the UE was connected to the source PCell before the last PCell change / HO procedure was performed) is greater than a configured threshold (e.g., thresholdPercentageT312 configured by the source PCell before the last PCell change / HO procedure was performed).

[0076] (3) The ratio between the value of the elapsed time of the target PCell's elapsed timer T304 and the configured value of timer T304 (i.e., included in the last applied RRCReconfiguration message, which includes reconfigurationWithSync for the PCell change / HO procedure) is greater than a configured threshold (e.g., thresholdPercentageT304 configured by the target PCell before performing the last PCell change / HO procedure).

[0077] Information related to a successful PCell change is included in the SHR, such as at least one of the following: cell information of the source PCell, cell information of the target PCell, SHR cause value (e.g., t304-Cause, t310-Cause, or t312-Cause), measurement results of the source PCell and / or target PCell when the HO is performed or successful, and RA information (e.g., RACH configuration of the target PCell). Generally, the cell information includes the cell's global cell identity and tracking area code, or PCI and frequency information (e.g., ARFCN).

[0078] The availability of an SHR may be indicated by a handover complete message (RRCReconfigurationComplete) transmitted from the UE to the target NG-RAN node via RRC. The target NG-RAN node may extract information from a successful handover report via the UE Information Request / Response mechanism. Additionally, the target NG-RAN node may then forward the SHR to the source NR-RAN node to indicate the failures experienced during a successful handover event.

[0079] Upon receiving the SHR, the receiving node can immediately analyze whether its mobility configuration needs to be adjusted. Such adjustments may result in a change in the mobility configuration, such as a change in the RLM configuration or a change in the mobility threshold between the source and target. In addition, in the executed handover, the target NG-RAN node can further optimize the dedicated RACH resources based on the measurements reported after the successful handover.

[0080] In 3GPP Rel-18, a successful PSCell change report (SPCR) will be introduced to optimize PSCell change or CPAC related parameters, for example, if a physical layer problem is detected by the UE during an ongoing legacy PSCell change procedure or an ongoing CPAC procedure. In order to report the SPCR, a configuration (e.g., a successPSCellChange-Config IE (information element)) for the UE to record or generate the SPCR is configured by the network, for example, via an RRCReconfiguration message, wherein the RRCReconfiguration message includes a timer T304 related threshold (a threshold generated by the target PSCell, such as thresholdPercentageT304), a timer T310 related threshold (a threshold generated by the source PSCell or source PCell, such as thresholdPercentageT310), or a timer T312 related threshold (a threshold generated by the source PSCell or source PCell, such as thresholdPercentageT312). Based on the network configuration, the UE needs to record or generate successful PSCell change related parameters when at least one trigger condition is met. An SPCR may be generated and reported to the network, which includes the Cell Global Identifier (CGI) information of the source PSCell, the CGI information of the target PSCell, a cause value for a successful PSCell change report (eg, t304-Cause, t310-Cause, or t312-Cause), and measurement results.

[0081] CHO without candidate SCGs may also be referred to as "CHO only," etc. Currently, there may be the following two scenarios:

[0082] (1) Use Case #1: The CHO configuration of the CHO with the candidate SCG program and the CHO configuration of the CHO without the candidate SCG (i.e., CHO-only) are configured separately. In this scenario, the CHO execution conditions of the CHO with the candidate SCG program and the CHO execution conditions of the CHO-only can be the same or different.

[0083] (2) Use Case #2: The CHO configuration of the CHO without the candidate SCG (ie, CHO only) is the same as the CHO configuration from the CHO with the candidate SCG program (ie, CHO part).

[0084] However, the following issues need to be addressed: how to ensure that CHO with candidate SCG procedures can be executed preferentially in use case #1; how to implement use case #2; how to implement some enhancements to use case #2; what are the enhanced trigger conditions for successful CHO and CPC procedures; and what additional information should be reported in the case of CHO with candidate SCG procedures.

[0085] Embodiments of the present application are intended to address the above-mentioned issues. For example, some embodiments of the present application provide mechanisms for use case #1 and use case #2. Some embodiments of the present application provide mechanisms for performing PCell / PSCell changes simultaneously in a CHO with a candidate SCG program. Some embodiments of the present application provide an MRO mechanism for a CHO with a candidate SCG program. Further details will be illustrated below in conjunction with the accompanying drawings.

[0086] Figure 3 The exemplary flowchart 300 illustrates an exemplary flow chart for accessing a candidate PCell according to some embodiments of the present application. Figure 1 and 6 8 and UE 101, UE 601, UE 701 or UE 801) to perform. Although described with respect to a UE, it should be understood that other devices may also be configured to perform the following. Figure 3 An exemplary flow chart is shown and illustrated in FIG.

[0087] In such Figure 3 In the exemplary flow chart 300 shown in FIG, in operation 301, the UE may receive RRC configuration information for a CHO having a candidate SCG for a CPC / CPA procedure (i.e., a CHO with a candidate SCG procedure). In operation 302, the UE may access the candidate PCell based on the RRC configuration information.

[0088] For example, the RRC configuration information may be included in an RRC reconfiguration message. In some embodiments, the RRC configuration information may include:

[0089] (1) CHO configuration associated with the candidate PCell (denoted as CHO configuration #1 for simplicity);

[0090] (2) CHO execution condition for the candidate PCell (denoted as CHO execution condition #1);

[0091] (3) configuration information for one or more candidate SCGs associated with one or more candidate PSCells; and

[0092] (4) A set of execution conditions for one or more candidate SCGs.

[0093] In some embodiments of exemplary flowchart 300, such as in use case #1, the UE may receive additional RRC configuration information for a CHO configuration without a candidate SCG (i.e., a CHO-only CHO configuration, denoted as CHO configuration #2). For example, the additional RRC configuration information and the RRC configuration information in operation 301 may be included in the same RRC reconfiguration message or in different RRC reconfiguration messages.

[0094] In an embodiment, a CHO execution condition may be configured for CHO configuration #2 (denoted as CHO execution condition #2). For example, the trigger time (TTT) for CHO execution condition #2 may be greater than the TTT for CHO execution condition #1.

[0095] In an embodiment, the additional RRC configuration information includes an indication (denoted as indication #1) indicating the association relationship between CHO configuration #2 and CHO configuration #1. For example, indication #1 may indicate that CHO configuration #2 is a supplement to CHO configuration #1. Figure 6 Specific examples are described in the embodiments of the present invention.

[0096] In some embodiments of exemplary flowchart 300, if indication #1 is received, the UE may consider CHO execution condition #2 for CHO configuration #2 to be the same as CHO execution condition #1 for the candidate PCell. Therefore, specific configuration of CHO execution condition #2 may be avoided.

[0097] In some embodiments of the exemplary flow chart 300, if CHO execution condition #2 for CHO configuration #2 (e.g., for CHO only) and CHO execution condition #1 for CHO configuration #1 (e.g., for CHO with candidate SCG procedure) are satisfied, the UE may:

[0098] (1) If a set of execution conditions for one candidate SCG within one or more candidate SCGs is met, then CHO is performed on the "candidate PCell" and "a candidate PSCell associated with the one candidate SCG" based on CHO configuration #1; or

[0099] (2) If a set of execution conditions for one or more candidate SCGs are not met, CHO is performed on the candidate PCell based on CHO configuration #2.

[0100] In some embodiments of exemplary flowchart 300, for example, in use case #2, the UE may receive an indication (denoted as indication #2) indicating that the UE is permitted to perform CHO based on a CHO configuration without a candidate SCG (e.g., CHO configuration #2). In some embodiments, the UE may receive an indication (denoted as indication #3) indicating that the CHO configuration without a candidate SCG associated with the candidate PCell (e.g., CHO configuration #2) is the same as the CHO configuration #1 associated with the candidate PCell. In some embodiments, the UE may receive both indication #2 and indication #3.

[0101] In an embodiment, if indication #2 and / or indication #3 are received, for example, via the Uu interface, the UE may consider the CHO configuration without a candidate SCG (e.g., CHO configuration #2) and the CHO configuration #1 associated with the candidate PCell (e.g., for CHO with a candidate SCG procedure) to be the same.

[0102] In an embodiment, if a set of execution conditions for one or more candidate SCGs is not met and CHO execution condition #1 is met, the UE may access the candidate PCell based on CHO configuration #2. After successfully accessing the candidate PCell (i.e., the target PCell) based on CHO configuration #2, the UE may release one or more SCG bearers configured in the one or more candidate SCGs, or the UE may remap one or more SCG bearers to MCG bearers configured in the candidate PCell.

[0103] According to some embodiments of exemplary flowchart 300, the UE may perform CHO based on CHO Configuration #1 or CHO Configuration #2. After successfully accessing the candidate PCell (i.e., the target PCell), the UE may transmit an RRC Reconfiguration Complete message to the candidate PCell. In some embodiments, the RRC Reconfiguration Complete message includes an indication of whether the UE performed CHO based on CHO Configuration #1 or CHO Configuration #2.

[0104] In an embodiment, the RRC reconfiguration complete message includes at least one of the following: an ID of a candidate PCell accessed by the UE; or an ID of a candidate PSCell accessed by the UE. For example, if the UE has performed CHO based on CHO configuration #2, the RRC reconfiguration complete message may include the ID of the candidate PCell. If the UE has performed CHO based on CHO configuration #1, the RRC reconfiguration complete message includes both the ID of the candidate PCell and the ID of the candidate PSCell. Figure 7 Specific examples are described in the embodiments of the present invention.

[0105] In some embodiments of the exemplary flowchart 300, in response to satisfying a trigger condition, the UE may transmit both a successful handover report (SHR) and a successful PSCell change report (SPCR) to the target network node. In an embodiment, the SHR and the SPCR are included in a UE information response message. For example, if a set of execution conditions for multiple SCGs within one or more candidate SCGs are satisfied, the UE may select one SCG from the multiple SCGs and perform CHO of the candidate SCG with the CPC / CPA procedure to access the one SCG. If a set of execution conditions for the multiple SCGs are satisfied, the UE information response message may also include ID information of other SCGs within the multiple SCGs except for the one SCG accessed by the UE. Figure 8 Specific examples are described in the embodiments of the present invention.

[0106] In an embodiment, the UE may receive a threshold value related to the trigger condition from the source network node. The threshold value may be a percentage value of the timer length. For example, the threshold value may be:

[0107] (1) a threshold value (denoted as Threshold #1) associated with a timer (e.g., timer T312) for initiating failure recovery based on triggering a measurement report; or

[0108] (2) a threshold (denoted as Threshold #2) associated with a physical layer problem timer (e.g., timer T310); or

[0109] (3) A threshold value (denoted as threshold value #3) associated with a switching timer (eg, timer T304).

[0110] In some embodiments, the triggering condition includes at least one of the following:

[0111] (1) The elapsed duration of the timer for initiating failure recovery based on a triggered measurement report (e.g., timer T312) exceeds a threshold #1 multiplied by the length of the timer for initiating failure recovery based on a triggered measurement report (e.g., timer T312);

[0112] (2) the elapsed duration of the physical layer problem timer (e.g., timer T310) exceeds threshold #2 multiplied by the length of the physical layer problem timer (e.g., timer T310); or

[0113] (3) The elapsed duration of the handover timer (eg, timer T304 ) exceeds threshold # 3 multiplied by the length of the handover timer (eg, timer T304 ).

[0114] Figure 4The exemplary flowchart 400 illustrates an exemplary flow chart for transmitting a handover request according to some embodiments of the present application. Figure 1 and 6 8, source gNB, source BS 602, source BS 702, or source BS 802). Although described with respect to a source network node, it should be understood that other devices may also be configured to perform the following. Figure 4 An exemplary flow chart is shown and illustrated in FIG.

[0115] In such Figure 4 In the exemplary flow chart 400 shown in FIG. 4 , in operation 401, a source network node may transmit a handover request for CHO. In operation 402, the source network node may receive a response from a candidate network node (e.g., a candidate gNB or a target gNB). The response may include at least one of the following:

[0116] (1) a CHO configuration associated with the candidate PCell (e.g., CHO configuration #1 described in exemplary flowchart 300);

[0117] (2) configuration information for one or more candidate SCGs associated with one or more candidate PSCells; or

[0118] (3) A set of execution conditions for one or more candidate SCGs.

[0119] In some embodiments of the exemplary flowchart 400, the source network node may receive an indication (denoted as indication #4) from the candidate network node, for example, via an Xn interface. Indication #4 may indicate that another CHO configuration associated with the candidate PCell (e.g., CHO configuration #2 described in the exemplary flowchart 300) is the same as the CHO configuration associated with the candidate PCell in operation 402, or indicate that only CHO configuration from the CHO configuration with the candidate SCG may be performed. In an embodiment, indication #4 is included in the handover request confirmation message. For example, the source network node may further transmit a similar indication (e.g., indication #3 described in the exemplary flowchart 300) to the UE. Figure 7 Specific examples are described in the embodiments of the present invention.

[0120] In some embodiments of exemplary flowchart 400, the source network node may send a message to a UE (e.g., Figure 1 and 6 8) transmits a threshold value related to a triggering condition. The triggering condition is used to trigger the simultaneous transmission of both the SHR and the SPCR. The threshold value may be a percentage value of the timer length. Figure 8Specific examples are described in the embodiments of the present invention.

[0121] According to some embodiments, the threshold is:

[0122] (1) a threshold value associated with a timer (e.g., timer T312) for initiating failure recovery based on triggering measurement reporting (e.g., threshold value #1 described in exemplary flowchart 300); or

[0123] (2) a threshold value associated with a physical layer problem timer (e.g., timer T310) (e.g., threshold value #2 described in exemplary flowchart 300); or

[0124] (3) A threshold value (eg, threshold value #3 as described in exemplary flowchart 300) associated with a switching timer (eg, timer T304).

[0125] According to some embodiments, the triggering condition includes at least one of the following:

[0126] (1) The elapsed duration of the timer for initiating failure recovery based on a triggered measurement report (e.g., timer T312) exceeds a threshold #1 multiplied by the length of the timer for initiating failure recovery based on a triggered measurement report (e.g., timer T312);

[0127] (2) the elapsed duration of the physical layer problem timer (e.g., timer T310) exceeds threshold #2 multiplied by the length of the physical layer problem timer (e.g., timer T310); or

[0128] (3) The elapsed duration of the handover timer (eg, timer T304 ) exceeds threshold # 3 multiplied by the length of the handover timer (eg, timer T304 ).

[0129] Figure 5 The exemplary flowchart 500 illustrates an exemplary flow chart for receiving a handover request according to some embodiments of the present application. Figure 1 and 6 8 , candidate gNB, candidate BS 603, candidate BS 703, or candidate BS 803). Although described with respect to a candidate network node, it should be understood that other devices may also be configured to perform the following. Figure 5 An exemplary flow chart is shown and illustrated in FIG.

[0130] In such Figure 5In the exemplary flow chart 500 shown in FIG, in operation 501, the candidate network node may receive a handover request for CHO from the source network node. In operation 502, the candidate network node may transmit a response to the source network node. The response may include at least one of the following:

[0131] (1) a CHO configuration associated with the candidate PCell (e.g., CHO configuration #1 described in exemplary flowchart 300);

[0132] (2) configuration information for one or more candidate SCGs associated with one or more candidate PSCells; and

[0133] (3) A set of execution conditions for one or more candidate SCGs.

[0134] In some embodiments of exemplary flowchart 500, the candidate network node may transmit an indication to the source network node, for example, via an Xn interface, indicating that another CHO configuration associated with the candidate PCell (e.g., CHO configuration #2 described in exemplary flowchart 300) is the same as the CHO configuration associated with the candidate PCell in operation 502.

[0135] In some embodiments of exemplary flowchart 500, the candidate network node may receive both an SHR and an SPCR from the UE. In response to a trigger condition being met, the UE may transmit both the SHR and the SPCR simultaneously. In some embodiments, the SHR and the SPCR are included in a UE Information Response message. In some embodiments, in response to a set of execution conditions being met for multiple SCGs within one or more candidate SCGs, the UE Information Response message further includes ID information for the other SCGs within the multiple SCGs, excluding the SCG accessed by the UE.

[0136] For example, the trigger condition includes at least one of the following:

[0137] (1) the elapsed duration of the timer for initiating failure recovery based on a triggered measurement report (e.g., timer T312) exceeds a threshold (e.g., threshold #1 described in exemplary flowchart 300) multiplied by the length of the timer for initiating failure recovery based on a triggered measurement report (e.g., timer T312);

[0138] (2) the elapsed duration of the physical layer problem timer (e.g., timer T310) exceeds a threshold (e.g., threshold #2 described in exemplary flowchart 300) multiplied by the length of the physical layer problem timer (e.g., timer T310); or

[0139] (3) The elapsed duration of the handover timer (eg, timer T304) exceeds a threshold (eg, threshold #3 described in exemplary flowchart 300) multiplied by the length of the handover timer (eg, timer T304).

[0140] In an embodiment, each of threshold #1, threshold #2, and threshold #3 is a percentage value of the timer length. Figure 8 Specific examples are described in the embodiments of the present invention.

[0141] All details described in other embodiments of this application apply to Figures 3 to 5 In addition, Figures 3 to 5 The details described in the embodiments apply to Figures 1 to 4 and all embodiments 6 to 9.

[0142] The following describes how Figures 3 to 5 The specific embodiment shown and illustrated in FIG, wherein the UE and the network nodes (eg, source base station (BS) and candidate BS) perform the following operations. It should be understood by those skilled in the art that changes may be made without departing from the spirit and scope of the present disclosure. Figures 6 to 8 The sequence of operations in any of the exemplary flowcharts 600, 700, and 800 in FIG. 1 and may be eliminated or modified Figures 6 to 8 Some operations in any of the exemplary flowcharts 600 to 800 in .

[0143] Figure 6 Illustrated is an exemplary flow chart related to CHO with candidate SCG procedures according to some embodiments of the present application. The details described in all other embodiments of the present application apply to Figure 6 The embodiments shown in . Figure 6 The example of reference use case #1.

[0144] In such Figure 6 In the exemplary flow chart 600 shown in FIG. 1 , in operation 611, a UE 601 in an RRC connected state accesses its serving BS (i.e., serving gNB, such as source BS 602). For example, dual connectivity (DC) may be configured for UE 601. In some embodiments, UE 601 may report measurement results to source BS 602 (e.g., source MN 602).

[0145] In operation 612, based on the measurement result, the source BS 602 may determine to transfer the UE 601 to the candidate BS 603 via CHO.

[0146] In operation 613, the source BS 602 may transmit a handover request message to the candidate BS 603. For example, the source BS 602 may instruct the candidate BS 603 to prepare a CHO configuration with a candidate SCG or a CHO configuration without a candidate SCG.

[0147] In operation 614, after receiving the handover request message from the source BS 602, if the candidate BS 603 (as the target MN) decides to prepare a candidate SCG, then the candidate BS 603 (i.e., the target MN 603) may transmit a request (e.g., an SgNB add request message or an SN modification request message) to the candidate SN 604 via the Xn interface.

[0148] In operation 615, the candidate SN 604 may transmit a confirmation message (e.g., SgNB Add Request Confirmation or SgNB Modify Request Confirmation) to the target MN 603. The CHO configuration for one or more candidate SCGs is included in the confirmation message.

[0149] In operation 616, after receiving the confirmation message from the candidate SN 604, the target MN 603 transmits a Handover Request Confirmation message (i.e., an Xn message) to the source BS 602 via the Xn interface. The Handover Request Confirmation message includes CHO configurations for one or more candidate SCGs. For example, a CHO configuration without a candidate SCG may be included in the same Xn message or in a separate Xn message. The target MN 603 may generate execution conditions for each candidate SCG.

[0150] In operation 617, after receiving the handover request confirmation message from the target MN 603, the source BS 602 transmits an RRC reconfiguration message to the UE 601, the RRC reconfiguration message including a CHO configuration for one or more candidate SCGs. For example, a corresponding CHO configuration without a candidate SCG may be transmitted to the UE 601 via the same RRC reconfiguration message or a different RRC reconfiguration message. The corresponding CHO configuration without a candidate SCG may include the same target PCell ID information as that included in the CHO configuration with one or more candidate SCGs.

[0151] In different embodiments of the present application, there may be the following two options, namely Option 1 and Option 2.

[0152] Option 1: The same execution condition may be configured for a CHO configuration without a candidate SCG and a CHO configuration with a candidate SCG.

[0153] For example, in option 1, in operation 617, the UE 601 may receive an indication indicating an association relationship (e.g., a complementary relationship) between the CHO configuration without a candidate SCG and the CHO configuration with a candidate SCG (e.g., indication #1 described in exemplary flowchart 300). The UE 601 may then consider that the execution condition for the CHO configuration without a candidate SCG is the same as the execution condition for the candidate PCell of the CHO configuration with a candidate SCG.

[0154] In an embodiment, the RRC information element (IE) may be as described below, which includes the above indication (eg, associatedCondReconfigId as described below) and the above configuration and execution conditions.

[0155] CondReconfigToAddModList Information Element (IE)

[0156]

[0157] Option 2: Different execution conditions may be configured for a CHO configuration without a candidate SCG and a CHO configuration with a candidate SCG, depending on the implementation scheme of the network.

[0158] Return Reference Figure 6 , in operation 618 , after receiving the RRC reconfiguration message for the CHO configuration with or without the candidate SCG from the source BS 602 , the UE 601 transmits an RRC reconfiguration complete message to the source BS 602 .

[0159] In operation 619 , the UE 601 starts evaluating an execution condition for a CHO configuration with a candidate SCG and an execution condition for a CHO configuration without a candidate SCG.

[0160] (1) For example, if in operation 617, UE 601 receives an indication indicating an association relationship between a CHO configuration without a candidate SCG and a CHO configuration with a candidate SCG (e.g., indication #1), then the execution condition for the CHO configuration with the candidate SCG may be the same as or associated with the execution condition for the CHO configuration without a candidate SCG.

[0161] (2) If the CHO execution conditions of the CHO with candidate SCG and the CHO without candidate SCG related to the same candidate PCell are satisfied, the CHO with candidate SCG procedure may be executed if the execution conditions of the candidate SCG are satisfied.

[0162] (3) If CHO execution conditions of CHO with candidate SCG and CHO without candidate SCG related to the same target PCell are satisfied, CHO without candidate SCG (ie, only CHO) may be executed without satisfying the execution conditions of the candidate SCG.

[0163] In exemplary flowchart 600, in some embodiments, in a case where CHO without a candidate SCG is configured for UE 601, execution conditions for candidate PCells from CHO without a candidate SCG and CHO with a candidate SCG are simultaneously satisfied. In this case, if the execution condition for the candidate SCG is also satisfied, UE 601 may prioritize executing CHO with the candidate SCG. If, when the execution conditions for candidate PCells from CHO without a candidate SCG and CHO with a candidate SCG are satisfied, the execution condition for the candidate SCG is not yet satisfied, UE 601 may not immediately execute CHO. Alternatively, a time offset may be configured for CHO without a candidate SCG for UE 601. That is, if the execution conditions for candidate PCells from CHO without a candidate SCG and CHO with a candidate SCG are simultaneously satisfied, but the execution condition for the candidate SCG is not yet satisfied, UE 601 needs to wait for a period of time. If the execution condition of the candidate SCG is still not satisfied after the time period, the UE 601 is allowed to perform CHO-only.

[0164] Figure 7 Illustrated is an exemplary flow chart related to CHO with candidate SCG procedures according to some embodiments of the present application. The details described in all other embodiments of the present application apply to Figure 7 The embodiments shown in . Figure 7 Refer to use case #2 for an example.

[0165] In such Figure 7 In the exemplary flow chart 700 shown in FIG. 7 , in operation 711, a UE 701 in an RRC connected state accesses its serving BS (i.e., a serving gNB, such as a source BS 702). For example, dual connectivity (DC) may be configured for the UE 701. In some embodiments, the UE 701 may report measurement results to the source BS 702 (e.g., the source MN 702).

[0166] In operation 712, based on the measurement result, the source BS 702 may determine to transfer the UE 701 to the candidate BS 703 via CHO.

[0167] In operation 713, the source BS 702 may transmit a handover request message to the candidate BS 703. For example, the source BS 702 may instruct the candidate BS 703 to prepare a CHO configuration with a candidate SCG or a CHO configuration without a candidate SCG.

[0168] In operation 714, after the candidate BS 703 receives the handover request message from the source BS 702, if the candidate BS 703 (as the target MN) decides to prepare a candidate SCG, the candidate BS 703 (i.e., the target MN 703) may transmit a request (e.g., an SgNB add request message or an SN modification request message) to the candidate SN 704 via the Xn interface.

[0169] In operation 715, the candidate SN 704 may transmit a confirmation message (e.g., SgNB Add Request Confirmation or SgNB Modify Request Confirmation) to the target MN 703. The CHO configuration for one or more candidate SCGs is included in the confirmation message.

[0170] In operation 716, after receiving the confirmation message from the candidate SN 704, the target MN 703 transmits a handover request confirmation message (ie, Xn message) to the source BS 702 via the Xn interface, the handover request confirmation message including CHO configuration for one or more candidate SCGs.

[0171] In an embodiment, the handover request confirmation message includes an indication (e.g., indication #4 described in exemplary flowchart 400) indicating that the CHO configuration without the candidate SCG and the CHO configuration from the CHO configuration with the candidate SCG (i.e., only the CHO configuration) associated with the candidate PCell are the same, or indicating that only the CHO configuration from the CHO configuration with the candidate SCG can be executed. More specifically, if the execution condition of the candidate SCG is not met, only the CHO configuration from the CHO configuration with the candidate SCG can be executed.

[0172] In operation 717, after receiving the handover request confirm message from the target MN 703, the source BS 702 transmits an RRC reconfiguration message containing the CHO configuration for the candidate SCG to the UE 701.

[0173] In an embodiment, the RRC reconfiguration message includes an indication (e.g., indication #2 described in exemplary flowchart 300) indicating that CHO is permitted to be performed by UE 701 based on the CHO configuration without a candidate SCG. If this indication is received, UE 701 may assume that the CHO-only configuration associated with the candidate PCell is the same as the CHO configuration associated with the candidate PCell for CHO with a candidate SCG procedure. Therefore, in this case, a separate configuration for CHO-only may be avoided. This indication may be referred to as a CHO-only indication, etc. UE 701 may perform CHO-only based on the CHO-only configuration.

[0174] In another embodiment, the RRC reconfiguration message includes an indication (e.g., indication #3 described in exemplary flowchart 300) indicating that the CHO configuration without the candidate SCG and the CHO configuration from the CHO configuration with the candidate SCG (i.e., only the CHO configuration) associated with the candidate PCell are the same, or indicating that only the CHO configuration from the CHO configuration with the candidate SCG can be performed. More specifically, if the execution condition of the candidate SCG is not met, the UE 701 can perform only the CHO configuration from the CHO configuration with the candidate SCG. In some examples, the RRC reconfiguration message may include both indication #2 and indication #3.

[0175] In another embodiment, the UE 701 may also receive a CHO-only configuration separate from the CHO configuration from the CHO with the candidate SCG, and then perform the CHO-only configuration based on the CHO-only configuration.

[0176] In an embodiment, the RRC IE is as follows, which includes the above indication (eg, CHOonlyallowed as described below) and the above configuration and execution conditions.

[0177] CondReconfigToAddModList information element

[0178]

[0179] If only CHO is performed, there may be different embodiments on how to handle the SCG bearers configured in the candidate SCG. In one embodiment, the UE 701 may release such SCG bearers. In another embodiment, the UE 701 may remap such SCG bearers to MCG bearers.

[0180] In operation 718 , the UE 701 starts evaluating execution conditions for the CHO configuration with the candidate SCG and for the CHO configuration without the candidate SCG (ie, CHO-only configuration).

[0181] In operation 719 , the UE 701 may perform a CHO with candidate SCG procedure or CHO only (ie, CHO without candidate SCG).

[0182] In operation 720, UE 701 may transmit an RRC reconfiguration complete message to target MN 703. In different embodiments, there may be the following two options, namely, option A and option B.

[0183] Option A: The RRC Reconfiguration Complete message may include an indication indicating based on which configuration the UE 701 has performed CHO (ie, based on CHO-only configuration or CHO configuration for CHO with candidate SCG procedure).

[0184] Option B: The RRC Reconfiguration Complete message includes the target PCell ID and / or the target PSCell ID, which can be used to indicate whether UE 701 performs CHO or CPC. For example, if the RRC Reconfiguration Complete message only includes the target PCell ID, this means that UE 701 has performed only CHO on the target PCell. If the RRC Reconfiguration Complete message includes both the target PCell ID and the target PSCell ID, this means that UE 701 has performed CHO on the target PCell and CPC / CPA on the target PSCell.

[0185] Figure 8 Illustrated is an exemplary flow chart related to CHO with candidate SCG procedures according to some embodiments of the present application. The details described in all other embodiments of the present application apply to Figure 8 The embodiments shown in .

[0186] In such Figure 8 In the exemplary flow chart 800 shown in FIG. 8 , in operation 811, a UE 801 in an RRC connected state accesses its serving BS (i.e., serving gNB, such as source BS 802). For example, dual connectivity (DC) may be configured for UE 801. In some embodiments, UE 801 may report measurement results to source BS 802 (e.g., source MN 802).

[0187] In operation 812, based on the measurement result, the source BS 802 may determine to transfer the UE 801 to the candidate BS 803 via CHO.

[0188] In operation 813, the source BS 802 may transmit a handover request message to the candidate BS 803. For example, the source BS 802 may instruct the candidate BS 803 to prepare a CHO configuration with a candidate SCG or a CHO configuration without a candidate SCG.

[0189] In operation 814, candidate BS 803 transmits a handover request confirmation message (i.e., an Xn message) to source BS 802 via the Xn interface. The handover request confirmation message includes a CHO configuration for one or more candidate SCGs. For example, a CHO configuration without a candidate SCG may be included in the same Xn message or in a separate Xn message. The execution condition for each candidate SCG may be generated by candidate BS 803 (also referred to as target MN 803).

[0190] In operation 815, after receiving the handover request confirmation message from candidate BS 803, source BS 802 transmits an RRC reconfiguration message to UE 801, the RRC reconfiguration message including a CHO configuration for one or more candidate SCGs. For example, a corresponding CHO configuration without a candidate SCG may be transmitted to UE 801 via the same RRC reconfiguration message or a different RRC reconfiguration message. The corresponding CHO configuration without a candidate SCG may include the same target PCell ID information as that included in the CHO configuration with one or more candidate SCGs.

[0191] In an embodiment, the RRC reconfiguration message includes a triggering condition for triggering the simultaneous transmission of both CHO-related information and CPC-related information (e.g., SHR and SPCR). For example, a new single threshold for timer T312, timer T311, or timer T304 for both the PCell and PSCell may be included in the RRC reconfiguration message. The threshold may be threshold #1, threshold #2, or threshold #3 as described in exemplary flowchart 300. The threshold may be a percentage value of the timer length. In one example, the threshold may be applied to both PCell changes and PSCell changes performed by UE 801. Once the threshold is triggered for a PCell change or a PSCell change, UE 801 may report both CHO-related information and CPC-related information (e.g., SHR and SPCR).

[0192] In operation 816 , after receiving the RRC reconfiguration message for the CHO configuration with or without the candidate SCG from the source BS 802 , the UE 801 transmits an RRC reconfiguration complete message to the source BS 802 .

[0193] In operation 817 , the UE 801 starts evaluating the execution conditions for the CHO configuration and the execution conditions for the candidate SCGs.

[0194] In operation 818, the UE 801 performs CHO with one candidate SCG, ie, both PCell change and PSCell change. After the UE 801 successfully accesses the target PCell and target PSCell, the SHR and SPCR may be triggered based on the following conditions.

[0195] (1) The elapsed duration of T312 exceeds a threshold (e.g., threshold #1) multiplied by the length of T312;

[0196] (2) the elapsed duration of T310 exceeds a threshold (e.g., threshold #2) multiplied by the length of T310; or

[0197] (3) The elapsed duration of T304 exceeds a threshold (eg, threshold #3) multiplied by the length of T304.

[0198] In operation 819, the UE 801 transmits an RRC message including an indication (eg, an available indication) to the candidate BS 803 (ie, the target MN 803) to indicate that the SHR and / or SPCR are available.

[0199] In operation 820, the target MN 803 may transmit a UE Information Request message to the UE 801 based on the available indication. The UE Information Request message may include an SHR and / or an SPCR.

[0200] In operation 821, UE 801 transmits a UE Information Response message to target MN 803. For example, the UE Information Response message may include an SHR and an SPCR. Furthermore, in an embodiment, UE 801 selects one SCG from among multiple suitable SCGs and performs CHO with the selected SCG. Therefore, it may report whether execution conditions of other SCGs within the multiple suitable SCGs are satisfied. Therefore, the UE Information Response message may further include whether execution conditions of other SCGs within the multiple suitable SCGs, other than the selected SCG, are satisfied.

[0201] In operation 822 , the target MN 803 transmits the received report from the UE 801 to the source MN 802 .

[0202] Figure 9 An exemplary block diagram illustrating an apparatus according to some embodiments of the present application is shown. Figure 9 , apparatus 900 may include at least one processor 904 and at least one transceiver 902 coupled to the processor 904. Apparatus 900 may be a UE or a network node (eg, a source network node or a candidate network node).

[0203] Although elements such as at least one transceiver 902 and a processor 904 are described in the singular in this figure, plural forms are also contemplated unless expressly stated to be limited to the singular. In some embodiments of the present application, the transceiver 902 may be divided into two devices, such as a receive circuit system and a transmit circuit system. In some embodiments of the present application, the device 900 may further include an input device, a memory, and / or other components.

[0204] In some embodiments of the present application, the device 900 may further include at least one non-transitory computer-readable medium. In some embodiments of the present disclosure, the non-transitory computer-readable medium may store computer-executable instructions thereon to cause the processor to implement the method described above with respect to the UE or the network node (e.g., the source BS or the candidate BS). For example, when the computer-executable instructions are executed, the processor 904 interacts with the transceiver 902 to perform, for example, Figures 3 to 8 The operations of any of the methods described herein.

[0205] Although the present disclosure has been described using its specific embodiments, it is apparent that many alternatives, modifications, and variations are apparent to those skilled in the art. For example, the various components of an embodiment may be interchanged, added, or replaced in other embodiments. Furthermore, not all elements of each figure are necessary for the operation of the disclosed embodiments. For example, those skilled in the art will be able to make and use the teachings of the present disclosure by simply adopting elements of independent technical solutions. Therefore, the embodiments of the present disclosure as set forth herein are intended to be illustrative, not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0206] In this document, the term "includes", "including" or any other variations thereof are intended to encompass non-exclusive inclusion, such that the process, method, article or equipment comprising a series of elements does not only comprise those elements, but may comprise other elements that are not explicitly listed or inherent to such process, method, article or equipment. Without further constraints, elements beginning with "a, an" etc. do not exclude the presence of additional identical elements in the process, method, article or equipment comprising the elements. In addition, the term "another" is defined as at least a second or more. As used herein, the term "having" etc. is defined as "comprising". For example, expressions such as "A and / or B" or "at least one of A and B" may include any and all combinations of the words listed together with the expression. For example, expressions such as "A and / or B" or "at least one of A and B" may include A, B or both A and B. The phrases "first", "second", etc. are only used to clearly illustrate the embodiments of the present application, rather than to limit the essence of the present application.

Claims

1. A user equipment (UE), comprising: transceiver; as well as a processor coupled to the transceiver, wherein the processor is configured to cause the UE to: receiving first radio resource control (RRC) configuration information for a CHO of a candidate secondary cell group (SCG) having a conditional primary secondary cell group (PSCell) change CPC / conditional PSCell add CPA procedure; and Access the candidate PCell based on the first RRC configuration information.

2. The UE according to claim 1, wherein the first RRC configuration information comprises: a first CHO configuration associated with the candidate primary cell PCell; a first CHO execution condition for the candidate PCell; Configuration information for one or more candidate SCGs associated with one or more candidate PSCells; and A set of execution conditions for the one or more candidate SCGs.

3. The UE according to claim 1 or claim 2, wherein the processor is configured to cause the UE to receive second RRC configuration information for a second CHO configuration without a candidate SCG. The UE according to claim 3 , wherein a second CHO execution condition is configured for the second CHO configuration. 5 . The UE according to claim 3 , wherein the second RRC configuration information includes a first indication indicating an association relationship between the second CHO configuration and the first CHO configuration. 6 . The UE according to claim 5 , wherein in response to receiving the first indication, the processor is configured to cause the UE to consider that a second CHO execution condition for the second CHO configuration is the same as the first CHO execution condition for the candidate PCell.

7. The UE of claim 6 , wherein, in response to satisfying both the second CHO execution condition for the second CHO configuration and the first CHO execution condition for the first CHO configuration, the processor is configured to cause the UE to: In response to satisfying the set of execution conditions for one candidate SCG within the one or more candidate SCGs, performing CHO on the candidate PCell and a candidate PSCell associated with the one candidate SCG based on the first CHO configuration; or In response to the set of execution conditions for the one or more candidate SCGs not being met, performing CHO on the candidate PCell based on the second CHO configuration.

8. The UE of claim 2, wherein the processor is configured to cause the UE to receive at least one of: a second indication indicating that CHO is allowed to be performed by the UE based on a second CHO configuration without a candidate SCG; or A third indication indicates that the second CHO configuration associated with the candidate PCell but without a candidate SCG is the same as the first CHO configuration associated with the candidate PCell. 9 . The UE of claim 8 , in response to receiving at least one of the second indication or the third indication, the processor is configured to cause the UE to consider that the second CHO configuration is the same as the first CHO configuration.

10. The UE according to claim 8 or claim 9, wherein: In response to the set of execution conditions for the one or more candidate SCGs not being satisfied and the first CHO execution condition being satisfied, the processor is configured to cause the UE to access the candidate PCell based on the second CHO configuration.

11. The UE according to claim 10, after successfully accessing the candidate PCell based on the second CHO configuration, the processor is configured to cause the UE to: releasing one or more SCG bearers configured in the one or more candidate SCGs; or The one or more SCG bearers are remapped to the master cell group MCG bearer configured in the candidate PCell.

12. The UE according to claim 1 or claim 9, the processor being configured to cause the UE to: performing CHO based on the first CHO configuration or the second CHO configuration; and After successfully accessing the candidate PCell, an RRC reconfiguration complete message is transmitted to the candidate PCell. 13 . The UE according to claim 12 , wherein the RRC reconfiguration complete message includes an indication indicating which one of the first CHO configuration and the second CHO configuration the UE has performed CHO based on.

14. A source network node, comprising: transceiver; as well as a processor coupled to the transceiver, wherein the processor is configured to cause the source network node to: transmitting a handover request to the CHO; and Receive a response from the candidate network node, wherein the response comprises: a first CHO configuration associated with the candidate primary cell PCell; and Configuration information for one or more candidate SCGs associated with one or more candidate PSCells.

15. A candidate network node, comprising: transceiver; as well as a processor coupled to the transceiver, wherein the processor is configured to cause the UE to: receiving a handover request for CHO from the source network node; and transmitting a response to the source network node, wherein the response comprises: a first CHO configuration associated with the candidate primary cell PCell; and Configuration information for one or more candidate SCGs associated with one or more candidate PSCells.

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