Method and apparatus for mro in ltm procedures

Abstract

Various aspects of the present disclosure pertain to methods and apparatuses for mobility robustness optimization (MRO) mechanisms for L1 / L2 triggered mobility (LTM) cell switching procedures. According to embodiments of the present disclosure, a secondary node (SN) includes at least one memory and at least one processor coupled to the at least one memory and configured to cause the SN to obtain failure information related to a L1 / L2 triggered mobility (LTM) primary secondary cell group cell (PSCell) switching procedure in response to an occurrence of a failure associated with the LTM PSCell switching procedure from a source PSCell to a target PSCell for a user equipment (UE), wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or a SCG failure.

Description

Technical Field

[0001] This disclosure relates to wireless communications, and more specifically, to methods and apparatus for L1 / L2 triggered mobility (LTM) cell handover procedures, including mobility robustness optimization (MRO) mechanisms for LTM primary / secondary cell group (PSCell) handover procedures or LTM primary cell (PCell) handover procedures. Background Technology

[0002] A wireless communication system may include one or more network communication devices, such as base stations, which can support wireless communication with one or more user communication devices, also referred to as user equipment (UE) or other suitable terms. The wireless communication system can support wireless communication with one or more user communication devices by utilizing the resources of the wireless communication system (e.g., time-domain resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency-domain resources (e.g., subcarriers, carriers, etc.)). Furthermore, the wireless communication system can support wireless communication across various radio access technologies, including third-generation (3G), fourth-generation (4G), fifth-generation (5G), and other suitable radio access technologies above 5G (e.g., sixth-generation (6G)). Summary of the Invention

[0003] The article “a” preceding an element is not limited and is understood to refer to “at least one” or “one or more” of those elements. The terms “a,” “at least one,” “one or more,” and “at least one of one or more” are interchangeable. As used herein (included in the claims), the word “or” used in a list of items (e.g., a list of items beginning with phrases such as “at least one of…”, “one or more of…”, or “one or both of…”) indicates an inclusive list, such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase “based on” should not be construed as a reference to a closed set of conditions. For example, an instance step described as “based on condition A” may be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase “based on” should be interpreted in the same manner as the phrase “at least partially based on.” Furthermore, as used herein (included in the claims), a “set” may comprise one or more elements.

[0004] In the secondary cell group (SCG) LTM procedure or the LTM PSCell handover procedure from the source PSCell to the target PSCell in a dual connectivity scenario, the node that generates the RRC reconfiguration message or determines to start the SCG LTM configuration for the SCG LTM / LTM PSCell handover procedure can be the MN or SN, or the CU of the MN or the CU of the SN. In addition, the SN can be the node that manages the serving PSCell or the source PSCell (e.g., the source SN), or the SN can be the node that manages the target PSCell for LTM (e.g., the target SN).

[0005] Some embodiments of this disclosure provide an auxiliary node (SN). The SN includes: at least one memory; and at least one processor coupled to the at least one memory and configured such that the SN: in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) to a target PSCell of a user equipment (UE), the SN obtains failure information related to the LTM PSCell handover procedure, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure.

[0006] In some implementations of the SN described herein, the processor is configured to cause the SN to perform one of the following, or the SN includes a centralized unit (CU) and the CU is configured to perform one of the following: receiving information about the failure type of the failure from the master node (MN), wherein the failure type is detected by the MN; or detecting the failure type of the failure.

[0007] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to verify the failure type after receiving information about the failure type from the MN.

[0008] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to: transmit first information to the MN indicating that the failure type detected by the MN is correct if the failure type is correct; or transmit second information to the MN indicating that the failure type detected by the MN is incorrect if the failure type is incorrect.

[0009] In some implementations of the SN described herein, the SN further includes at least one distributed unit (DU), the CU being configured to transmit at least one of the following to the at least one DU: the failure information related to the LTM PSCell handover procedure; the information of the failure type received from the MN; or the information of the failure type detected by the CU.

[0010] In some implementations of the SN described herein, the at least one DU is configured to: detect the failure type of the failure; or verify the failure type detected by the MN or by the CU.

[0011] In some embodiments of the SN described herein, the at least one DU is configured to: transmit to the CU the failure type detected by the at least one DU; or if the failure type detected by the MN or the CU is correct, then transmit to the CU information indicating that the failure type detected by the MN or the CU is correct; or if the failure type detected by the MN or the CU is incorrect, then transmit to the CU information indicating that the failure type detected by the MN or the CU is incorrect.

[0012] In some embodiments of the SN described herein, the processor is configured such that the SN or the CU is configured to indicate to the MN the failure type detected by the SN or the CU, or the failure type verified by the SN or the CU, or the failure type detected by the at least one DU, or the failure type verified by the at least one DU.

[0013] In some embodiments of the SN described herein, the processor is configured such that the SN or the CU is configured to transmit to the MN at least one of the following: information indicating that the failure type detected by the MN is an error; or information indicating that the failure type detected by the MN is correct.

[0014] In some implementations of the SN described herein, the failure type includes at least one of the following: a first failure type, defined as too late SCG LTM, wherein the UE has received configuration information for the LTM PSCell handover procedure, but the SCG failure occurs after the UE has remained in the source PSCell for a certain period of time or before the LTM PSCell handover command that triggers the LTM PSCell handover procedure to the UE, and a suitable PSCell different from the source PSCell is found based on Layer 1 (L1) or Layer 3 (L3) measurements reported by the UE; a second failure type, defined as too early SCG LTM, wherein the SCG failure occurs shortly after the successful completion of the LTM PSCell handover from the source PSCell to the target PSCell or the SCG LTM execution fails, and the source PSCell is the suitable PSCell based on the L1 or L3 measurements reported by the UE; or a third failure type, defined as SCG LTM to an incorrect PSCell, wherein the SCG failure occurs during the LTM from the source PSCell to the target PSCell. Shortly after the successful completion of the PSCell handover or when the SCG LTM execution fails, the appropriate PSCell, which is different from the source PSCell and the target PSCell, is found based on the L1 or L3 measurement results reported by the UE.

[0015] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to: receive information about a suitable PSCell or select the suitable PSCell in response to the occurrence of the failure.

[0016] In some implementations of the SN described herein, the suitable PSCell is selected by the MN, and the information of the suitable PSCell is received from the MN.

[0017] In some implementations of the SN described herein, the SN includes a centralized unit (CU) and at least one distributed unit (DU), and the CU is configured to transmit the information of the appropriate PSCell to the at least one DU.

[0018] In some implementations of the SN described herein, the suitable PSCell is selected by the SN or the CU.

[0019] In some implementations of the SN described herein, the SN further includes at least one distributed unit (DU), the appropriate PSCell is selected by the at least one DU, and the information of the appropriate PSCell is received by the CU from the at least one DU.

[0020] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to transmit the information of the appropriate PSCell to the MN.

[0021] In some implementations of the SN described herein, the failure type further includes at least one of the following: a fourth failure type, wherein the suitable PSCell selected in response to the occurrence of the failure is not one of the first set of LTM candidate PSCells provided by the CU of the SN to at least one DU of the SN; a fifth failure type, wherein the suitable PSCell is one of the first set of LTM candidate PSCells, but not one of the second set of LTM candidate PSCells selected by the at least one DU; or a sixth failure type, wherein the suitable PSCell is one of the second set of LTM candidate PSCells.

[0022] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to detect whether the failure type is one of the fourth failure type, the fifth failure type, and the sixth failure type.

[0023] In some implementations of the SN described herein, if the failure type is the fourth failure type, then it is inappropriate for the processor to be configured such that the SN or the CU is configured to determine the first set of LTM candidate PSCells provided by the SN or the CU.

[0024] In some implementations of the SN described herein, the SN further includes at least one distributed unit (DU), and wherein the processor is configured such that the SN or the DU is configured to transmit to the MN or the at least one DU information indicating that the first set of LTM candidate PSCells provided by the SN or the DU is inappropriate.

[0025] In some implementations of the SN described herein, the SN further includes at least one distributed unit (DU), and if the failure type is the fifth failure type, the CU is configured to: detect the selection of one or more erroneous LTM candidate PSCells by the at least one DU; or transmit third information to the at least one DU indicating that the at least one DU has selected the one or more erroneous LTM candidate PSCells.

[0026] In some implementations of the SN described herein, the at least one DU is configured to verify the failure type or whether the at least one DU selects one or more error LTM candidate PSCells.

[0027] In some implementations of the SN described herein, the at least one DU is configured to transmit to the CU one of the following: information indicating that the CU has performed a correct detection of the third information; information indicating that the CU has performed an incorrect detection of the third information; or information of the failure type detected or verified by the at least one DU.

[0028] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to transmit to the MN the information of the failure type detected or verified by the at least one DU.

[0029] In some implementations of the SN described herein, if the failure type is the sixth failure type, then the CU is configured to: detect the selection of an incorrect LTM target PSCell by the source DU of the SN; or transmit fourth information to the source DU indicating that the source DU has selected the incorrect LTM target PSCell.

[0030] In some implementations of the SN described herein, the source DU is configured to verify the failure type or whether the source DU selects the error LTM target PSCell.

[0031] In some implementations of the SN described herein, the source DU is configured to transmit to the CU one of the following: information indicating that the CU has performed a correct detection of the fourth information; information indicating that the CU has performed an incorrect detection of the fourth information; or information of the failure type detected or verified by the source DU.

[0032] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to transmit the information of the failure type detected or verified by the source DU to the MN.

[0033] In some implementations of the SN described herein, the SN further includes at least one distributed unit (DU); wherein the DU is configured to transmit at least one of the failure information or the information of the appropriate PSCell to the at least one DU; and wherein the at least one DU is configured to detect the failure type.

[0034] In some implementations of the SN described herein, if the failure type is the fourth failure type, then the at least one DU is configured to: detect that the first set of LTM candidate PSCells provided by the CU is inappropriate; or transmit a fifth message to the CU indicating that the first set of LTM candidate PSCells provided by the CU is inappropriate.

[0035] In some implementations of the SN described herein, if the failure type is the fifth failure type, then the at least one DU is configured to: detect the selection of one or more erroneous LTM candidate PSCells by the at least one DU; or transmit sixth information to the CU indicating that the at least one DU has selected the one or more erroneous LTM candidate PSCells.

[0036] In some implementations of the SN described herein, if the failure type is the sixth failure type, then the source DU is configured to: detect that the source DU has selected an incorrect LTM target PSCell; or transmit seventh information to the CU indicating that the source DU has selected the incorrect LTM target PSCell.

[0037] In some implementations of the SN described herein, the processor is configured such that the SN or the CU is configured to transmit the fifth, sixth, or seventh information to the MN.

[0038] In some implementations of the SN described herein, the SN includes a centralized unit (CU) for obtaining the failure information. The processor is configured such that the SN or the CU is configured to derive the failure information itself or receive the failure information stored or transmitted by the UE. The failure information includes at least one of the following: information about the source PSCell; information about the PSCell where the failure occurred; information about the selected beam in the target PSCell; information about one or more neighboring cells; L1 or L3 measurement results of the source PSCell; L1 or L3 measurement results of the PSCell where the failure occurred; L1 or L3 measurement results of the neighboring cells; information indicating whether the neighboring cells included in the L1 or L3 measurement results are LTM candidate PSCells; information indicating that the failure occurred during the LTM PSCell handover procedure; information about at least one LTM candidate PSCell configured for the LTM PSCell handover procedure; cell configuration information of the at least one LTM candidate PSCell; a set of Channel State Information (CSI) resources for the LTM PSCell handover procedure; and the LTM... The reference configuration of the PSCell handover procedure; the time elapsed between the reception of the LTM PSCell handover command and the reception of the most recent RRC reconfiguration message of the LTM PSCell handover procedure; the time elapsed between the reception of the LTM PSCell handover command and the occurrence of the failure; the time elapsed between the occurrence of the failure and the transmission of the failure information by the UE; the time alignment (TA) value of the SCG LTM without a random access channel (RACH); or the TA value derived in the early RACH procedure for early TA acquisition.

[0039] In some implementations of the SN described herein, the SN includes at least one distributed unit (DU), and the CU is configured to transmit the failure information to the at least one DU after receiving the failure information.

[0040] In some implementations of the SN described herein, the SN includes a centralized unit (CU) and at least one distributed unit (DU), wherein the processor is configured to enable the SN or the CU to detect whether a ping-pong event has occurred, and wherein, for the ping-pong event, after a successful LTM PSCell handover from a first PSCell to a second PSCell, the UE hands back to the first PSCell within a predefined period or the UE successfully performs another LTM PSCell handover from the second PSCell back to the first PSCell.

[0041] In some implementations of the SN described herein, the CU is configured to transmit information to the at least one DU indicating the occurrence of the ping-pong event.

[0042] In some implementations of the SN described herein, the ping-pong event is detected based on: the UE's historical information; the duration between receiving two LTM cell change notification messages on the same PSCell; or the duration between receiving two access success messages on the same PSCell.

[0043] In some embodiments of the SN described herein, the at least one DU of the SN is at least one of the following: a source DU; a target DU; or at least one candidate target DU.

[0044] Some embodiments of this disclosure provide a processor for wireless communication, including at least one controller coupled to at least one memory and configured such that the processor: in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) of a user equipment (UE) to a target PSCell, the processor obtains failure information related to the LTM PSCell handover procedure, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure.

[0045] Some embodiments of this disclosure provide a method performed by a secondary node (SN). The method includes: obtaining failure information related to the LTM PSCell handover procedure in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) of a user equipment (UE) to a target PSCell, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure.

[0046] Some embodiments of this disclosure provide an auxiliary node (SN). The SN includes: at least one memory; and at least one processor coupled to the at least one memory and configured such that the SN: receives from or transmits to the master node (MN) physical random access channel (PRACH) configuration information for an early timing advance (TA) acquisition triggered random access (RA) procedure.

[0047] Some embodiments of this disclosure provide a processor for wireless communication, including at least one controller coupled to at least one memory and configured such that the processor receives or transmits physical random access channel (PRACH) configuration information from or to a master node (MN) for an early timing advance (TA) fetch triggered random access (RA) procedure.

[0048] Some embodiments of this disclosure provide a method performed by an auxiliary node (SN). The method includes: receiving from or transmitting to the master node (MN) physical random access channel (PRACH) configuration information for an early timing advance (TA) acquisition-triggered random access (RA) procedure.

[0049] Some embodiments of this disclosure provide an auxiliary node (SN). The SN includes: at least one memory; and at least one processor coupled to the at least one memory and configured to receive random access (RA) reports from a user equipment (UE) or a master node (MN), wherein the RA report includes at least one of the following: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0050] Some embodiments of this disclosure provide a processor for wireless communication, comprising at least one controller coupled to at least one memory and configured to: receive a random access (RA) report from a user equipment (UE) or a master node (MN), wherein the RA report contains at least one of: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0051] Some embodiments of this disclosure provide a method performed by an auxiliary node (SN). The method includes receiving a random access (RA) report from a user equipment (UE) or a primary node (MN), wherein the RA report includes at least one of: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0052] Some embodiments of this disclosure provide a master node (MN). The MN includes: at least one memory; and at least one processor coupled to the at least one memory and configured such that the MN: in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) to a target PSCell of a user equipment (UE), performs at least one of the following: receiving failure information related to the LTM PSCell handover procedure from the UE; or obtaining information about the failure type of the failure, wherein the failure includes at least one of secondary cell group (SCG) LTM execution failure or SCG failure.

[0053] In some implementations of the MN described herein, the processor is configured to cause the MN to transmit the failure information to the SN.

[0054] In some implementations of the MN described herein, the failure information includes at least one of the following: information about the source PSCell; information about the PSCell where the failure occurred; information about the selected beam in the target PSCell; information about one or more neighboring cells; L1 or L3 measurement results of the source PSCell; L1 or L3 measurement results of the PSCell where the failure occurred; L1 or L3 measurement results of the neighboring cells; information indicating whether the neighboring cells included in the L1 or L3 measurement results are LTM candidate PSCells; information indicating that the failure occurred in the LTM PSCell handover procedure; information about at least one LTM candidate PSCell configured for the LTM PSCell handover procedure; cell configuration information of the at least one LTM candidate PSCell; a set of Channel State Information (CSI) resources for the LTM PSCell handover procedure; a reference configuration for the LTM PSCell handover procedure; the time elapsed between the receipt of the LTM PSCell handover command and the receipt of the most recent RRC reconfiguration message for the LTM PSCell handover procedure; and the time elapsed between the receipt of the LTM PSCell handover command and the receipt of the most recent RRC reconfiguration message for the LTM PSCell handover procedure. The time elapsed between the receipt of the PSCell handover command and the occurrence of the failure; the time elapsed between the occurrence of the failure and the transmission of the failure information by the UE; the time alignment (TA) value of the SCG LTM without a random access channel (RACH); or the TA value derived in the early RACH procedure for early TA acquisition.

[0055] In some implementations of the MN described herein, in order to obtain the information about the failure type, the processor is configured to cause the MN to perform at least one of the following: detect the failure type; receive the information about the failure type from the SN; or transmit the information about the failure type detected by the MN to the SN.

[0056] In some implementations of the MN described herein, the processor is configured to receive from the SN one of the following: information indicating that the failure type detected by the MN is correct; information indicating that the failure type detected by the MN is incorrect; information indicating the failure type detected by the SN; or information indicating the failure type verified by the SN.

[0057] In some implementations of the MN described herein, the failure type includes at least one of the following: a first failure type, defined as a late SCG LTM, wherein the UE has received configuration information for the LTM PSCell handover procedure, but the SCG failure occurs after the UE has remained in the source PSCell for a certain period of time or before an LTM PSCell handover command triggering the LTM PSCell handover procedure to the UE, and a suitable PSCell different from the source PSCell is found based on Layer 1 (L1) or Layer 3 (L3) measurements reported by the UE; a second failure type, defined as a premature SCG LTM, wherein the SCG failure occurs shortly after the successful completion of an LTM PSCell handover from the source PSCell to the target PSCell or the SCG LTM execution fails, and the source PSCell is the suitable PSCell based on the L1 or L3 measurements reported by the UE; or a third failure type, defined as an SCG LTM to an incorrect PSCell, wherein the SCG failure occurs during the LTM from the source PSCell to the target PSCell. Shortly after the successful completion of the PSCell handover or when the SCG LTM execution fails, the appropriate PSCell, which is different from the source PSCell and the target PSCell, is found based on the L1 or L3 measurement results reported by the UE.

[0058] In some implementations of the MN described herein, the processor is configured to cause the MN to: select a suitable PSCell in response to the occurrence of the failure; and transmit information about the suitable PSCell to the SN.

[0059] In some implementations of the MN described herein, the MN includes a centralized unit (CU) and at least one distributed unit (DU), the CU or the at least one DU being configured to select the appropriate PSCell.

[0060] In some implementations of the MN described herein, the processor is configured to enable the MN to receive information about a suitable PSCell from the SN, and the suitable PSCell is selected by the SN.

[0061] In some implementations of the MN described herein, in response to the occurrence of the failure, the failure type includes at least one of the following: a fourth failure type, wherein the suitable PSCell selected in response to the occurrence of the failure is not one of the first set of LTM candidate PSCells provided by the CU of the SN to at least one DU of the SN; a fifth failure type, wherein the suitable PSCell is one of the first set of LTM candidate PSCells, but not one of the second set of LTM candidate PSCells selected by the at least one DU of the SN; or a sixth failure type, wherein the suitable PSCell is one of the second set of LTM candidate PSCells.

[0062] In some embodiments of the MN described herein, the processor is configured to receive from the SN one of the following: information indicating that the first set of LTM candidate PSCells provided by the SN or the CU of the SN is inappropriate; information indicating that the SN or the at least one DU of the SN selects the one or more erroneous LTM candidate PSCells; information indicating that the SN or the source DU of the SN selects the erroneous LTM target PSCell; information on the failure type detected or verified by the at least one DU of the SN; information on the failure type detected or verified by the source DU of the SN; or information on the failure type detected or verified by the SN.

[0063] Some embodiments of this disclosure provide a processor for wireless communication, comprising at least one controller coupled to at least one memory and configured such that the processor: in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) of a user equipment (UE) to a target PSCell, performs at least one of the following: receiving failure information related to the LTM PSCell handover procedure from the UE; or obtaining information on the failure type of the failure, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure.

[0064] Some embodiments of this disclosure provide a method performed by a master node (MN). The method includes: in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) of a user equipment (UE) to a target PSCell, performing at least one of the following: receiving failure information related to the LTM PSCell handover procedure from the UE; or obtaining information about the failure type of the failure, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure.

[0065] Some embodiments of this disclosure provide a master node (MN). The MN includes: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the MN to: transmit to or receive from an auxiliary node (SN) physical random access channel (PRACH) configuration information for a random access (RA) procedure triggered by early timing advance (TA) fetch.

[0066] Some embodiments of this disclosure provide a processor for wireless communication, including at least one controller coupled to at least one memory and configured to cause the processor to: transmit to or receive from an auxiliary node (SN) physical random access channel (PRACH) configuration information for a random access (RA) procedure triggered by early timing advance (TA) fetch.

[0067] Some embodiments of this disclosure provide a method performed by a master node (MN). The method includes: transmitting to a source auxiliary node (SN) or receiving from a source auxiliary node (SN) physical random access channel (PRACH) configuration information for a random access (RA) procedure triggered by early timing advance (TA) acquisition.

[0068] Some embodiments of this disclosure provide a master node (MN). The MN includes: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the MN to perform at least one of the following: receiving a random access (RA) report from a user equipment (UE); or transmitting the RA report to a source auxiliary node (SN), wherein the RA report includes at least one of the following: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0069] Some embodiments of this disclosure provide a processor for wireless communication, comprising at least one controller coupled to at least one memory and configured to cause the processor to perform at least one of the following: receiving a random access (RA) report from a user equipment (UE); or transmitting the RA report to a source auxiliary node (SN), wherein the RA report contains at least one of the following: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0070] Some embodiments of this disclosure provide a method performed by a master node (MN). The method includes at least one of the following: receiving a random access (RA) report from a user equipment (UE); or transmitting the RA report to a source auxiliary node (SN), wherein the RA report includes at least one of the following: Early Random Access Channel (RACH) procedure-related information; L1 / L2 triggered mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0071] Some embodiments of this disclosure provide a user equipment (UE). The UE includes: at least one memory; and at least one processor coupled to the at least one memory and configured such that the UE: in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from the UE's source primary / secondary cell group (PSCell) to a target PSCell, the failure including at least one of secondary cell group (SCG) LTM execution failure or SCG failure; and transmits the failure information.

[0072] In some implementations of the UE described herein, the failure information includes at least one of the following: information about the source PSCell; information about the PSCell where the failure occurred; information about the selected beam in the target PSCell; information about one or more neighboring cells; L1 or L3 measurement results of the source PSCell; L1 or L3 measurement results of the PSCell where the failure occurred; L1 or L3 measurement results of the neighboring cells; information indicating whether the neighboring cells included in the L1 or L3 measurement results are LTM candidate PSCells; information indicating that the failure occurred in the LTM PSCell handover procedure; information about at least one LTM candidate PSCell configured for the LTM PSCell handover procedure; cell configuration information of the at least one LTM candidate PSCell; a set of Channel State Information (CSI) resources for the LTM PSCell handover procedure; a reference configuration for the LTM PSCell handover procedure; the time elapsed between the reception of the LTM PSCell handover command and the reception of the most recent RRC reconfiguration message for the LTM PSCell handover procedure; and the time elapsed between the reception of the LTM PSCell handover command and the reception of the most recent RRC reconfiguration message for the LTM PSCell handover procedure. The time elapsed between the receipt of the PSCell handover command and the occurrence of the failure; the time elapsed between the occurrence of the failure and the transmission of the failure information by the UE; the time alignment (TA) value of the SCG LTM without a random access channel (RACH); or the TA value derived in the early RACH procedure for early TA acquisition.

[0073] Some embodiments of this disclosure provide a processor for wireless communication, comprising at least one controller coupled to at least one memory and configured to: store failure information related to the LTM PSCell handover procedure in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) of the UE to a target PSCell, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure; and transmit the failure information.

[0074] Some embodiments of this disclosure provide a method performed by a user equipment (UE). The method includes: storing failure information related to the LTM PSCell handover procedure in response to the occurrence of a failure associated with an L1 / L2 triggered mobility (LTM) PSCell handover procedure from a source primary / secondary cell group (PSCell) of the UE to a target PSCell, wherein the failure includes at least one of a secondary cell group (SCG) LTM execution failure or an SCG failure; and transmitting the failure information.

[0075] Some embodiments of this disclosure provide a user equipment (UE). The UE includes: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the UE to: store or transmit random access (RA) reports, wherein the RA reports include at least one of: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for Early Timing Advance (TA) acquisition.

[0076] Some embodiments of this disclosure provide a processor for wireless communication, including at least one controller coupled to at least one memory and configured to: store or transmit random access (RA) reports, wherein the RA reports include at least one of: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for Early Timing Advance (TA) acquisition.

[0077] Some embodiments of this disclosure provide a method performed by a user equipment (UE). The method includes: storing or transmitting a random access (RA) report, wherein the RA report includes at least one of: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition. Attached Figure Description

[0079] Figure 1 Examples of wireless communication systems according to aspects of this disclosure are described.

[0080] Figure 2 An example of a user equipment (UE) 200 according to aspects of this disclosure is described.

[0081] Figure 3 An example of processor 300 according to aspects of this disclosure is described.

[0082] Figure 4 Examples of network equipment (NE) 400 according to aspects of this disclosure are described.

[0083] Figure 5A A schematic diagram illustrating a mobility scenario within a CU and DU according to aspects of this disclosure.

[0084] Figure 5B A schematic diagram illustrating a scenario of mobility between DUs within a CU according to aspects of this disclosure.

[0085] Figure 5C A schematic diagram illustrating a scenario of inter-CU mobility according to aspects of this disclosure.

[0086] Figure 6 A schematic diagram illustrating the LTM procedure for DU-CU within NR according to aspects of this disclosure.

[0087] Figure 7 A flowchart illustrating a method related to the LTM PSCell switching procedure according to aspects of this disclosure. Detailed Implementation

[0088] Generally, when a UE moves from one cell to another, a serving cell change needs to be performed at some point. Traditionally, serving cell changes are accomplished through explicit RRC reconfiguration signaling (e.g., handover (HO) commands) used to trigger synchronization of the target cell based on L3 measurement reports. Compared to beam-level mobility, this results in longer latency, greater overhead, and longer downtime. Therefore, in 3GPP, LTM is permitted to change serving cells via L1 / L2 signaling to reduce latency, overhead, and downtime.

[0089] LTM is a procedure in which the BS receives L1 measurement reports from the UE, and based on these reports, the BS changes the UE's serving cell via a cell handover command signaled by a Media Access Control (MAC) element (CE), such as an LTM Cell Handover MAC CE or an LTM Command MAC CE. The cell handover command indicates the LTM target cell, such as an LTM candidate cell configuration previously prepared by the BS and provided to the UE via RRC signaling. The UE then hands over to the LTM target cell according to the cell handover command. LTM procedures can be used to reduce mobility latency.

[0090] In some cases, subsequent LTM may be supported. Subsequent LTM refers to a subsequent LTM cell handover procedure between LTM candidate cells in which the UE does not require reconfiguration by the network in between.

[0091] A supervisory timer can be used to detect failures in LTM execution or LTM cell handover procedures. If the LTM supervisory timer expires, the LTM procedure fails, and the UE initiates an RRC connection re-establishment procedure. For example, the conventional T304 timer is used as a supervisory timer to monitor the LTM cell handover procedure.

[0092] "LTM candidate PSCell" refers to a candidate PSCell configured for the UE for SCG LTM or LTM PSCell handover. Multiple LTM candidate PSCells may exist for a UE, and these candidate PSCells may belong to the same or different candidate DUs of the CU of the SN. The SN can be a source SN, a target SN, or a candidate target SN. The source SN is the node that manages the source PSCell, the target SN is the node that manages the LTM target PSCell, and the candidate target SN is the node that manages one or more LTM candidate PSCells.

[0093] "LTM Candidate PSCell Configuration" refers to the configuration associated with an LTM candidate PSCell. An LTM candidate PSCell configuration can be a complete LTM candidate PSCell configuration or a differential configuration relative to an LTM reference configuration. Each LTM candidate PSCell configuration is identified by an index, referred to as the LTM candidate PSCell configuration index, LTM candidate configuration index, or other names. In one instance, the LTM candidate PSCell configuration index is LTM-CandidateId, which identifies the LTM candidate PSCell configuration.

[0094] "LTM Reference Configuration" refers to the configuration provided by the network to the UE that is common to all configured LTM candidate PSCells. The UE uses it to generate the complete LTM candidate PSCell configuration (i.e., by applying the LTM candidate PSCell configuration on top of the LTM Reference Configuration).

[0095] "Complete LTM Candidate PSCell Configuration" refers to a configuration containing all the necessary fields required to perform the LTM PSCell switching procedure. This configuration can be generated either by the LTM Candidate PSCell Configuration itself or by applying the LTM Candidate PSCell Configuration on top of the LTM Reference Configuration.

[0096] In dual-connectivity scenarios, SCG LTM or LTM PSCell handover is a PSCell handover procedure triggered by the MAC CE based on L1 measurements. In 3GPP Rel-18, intra-SN SCG LTM without involving the MN is supported. Subsequent 3GPP releases will also support intra-SN SCG LTM involving the MN and / or inter-SN SCG LTM. Potential applicable scenarios for SCG LTM or LTM PSCell handover include "CU-internal / DU-internal LTM," "CU-internal / DU-internal LTM," and "CU-internal LTM," as described below. Figures 5A to 5C It is displayed in the middle.

[0097] (1) Mobility within CU and DU: The UE moves between different cells within the DU of the SN (e.g., in the case of SCG LTM within the SN with or without MN, the SN is the source SN).

[0098] (2) Mobility between DUs within a CU: The UE moves between different cells within the same CU of a SN (e.g., in the case of SCGLTM within a SN involving or not involving an MN, the SN is the source SN) but in the same CU of the SN (e.g., in the case of SCG LTM within a SN involving or not involving an MN, the SN is the source SN).

[0099] (3) Inter-CU mobility: The UE moves between different cells belonging to different DUs and different CUs.

[0100] Generally, the purpose of the SCG failure information procedure is to notify the E-UTRAN or NR MN of an SCG failure experienced by the UE, namely, SCG radio link failure, failure of synchronized SCG reconfiguration, failure of SCG configuration of RRC messages on Signaling Radio Bearer (SRB) 3, failure of SCG integrity check, and failure of consistent uplink listen-before-talk (LBT) for shared spectrum channel access operation on PSCell. The failure type, measurement results in MCG, and / or measurement results in SCG may be included in the SCG failure information message. After the network receives the SCG failure information message, it may trigger the UE to perform SN release, modification, or change procedures. In the case of an SCG failure, the following information (e.g., SCG failure-related information) may be included in the SCG failure information message: cell information of the previous PSCell; cell information of the failed PSCell; time of SCG failure, indicating the time elapsed since the last execution of an RRC reconfiguration with SCG reconfigurationWithSync until the SCG failure; RA information; and / or failure type. Cell information may include a global cell identifier, the cell tracking area code and / or physical cell identifier (PCI) and carrier frequency information.

[0101] One of the self-optimization features for PSCell changes is the detection of PSCell change failures caused by excessively late or premature PSCell changes, or by triggering a PSCell change to an incorrect PSCell. These issues can be defined as follows:

[0102] - Late PSCell Change: SCG failure occurs after the UE has been in a PSCell for an extended period of time; the appropriate different PSCell is found based on measurements reported from the UE.

[0103] - Premature PSCell Change: SCG failure occurs shortly after a successful PSCell change from source PSCell to target PSCell or during the PSCell change procedure; the source PSCell is still the appropriate PSCell based on the measurement reported from the UE.

[0104] - Triggering a PSCell change to an incorrect PSCell: SCG failure occurs shortly after a successful PSCell change from the source PSCell to the target PSCell or during the PSCell change procedure; the appropriate PSCell, which is different from the source PSCell or the target PSCell, is found based on measurements reported from the UE.

[0105] In the above definition, "successful PSCell change" refers to the UE state, that is, the successful completion of the RA procedure.

[0106] One objective of mobility enhancements in 3GPP Rel-18 is to specify the SCG LTM procedure (i.e., the PSCell handover procedure triggered by the network via MAC CE based on L1 measurement results) in dual-connectivity scenarios. During SCG LTM or LTM PSCell handover procedures, SCG LTM execution failure, LTM PSCell handover failure, or SCG failure may occur. To improve mobility robustness, the following issues regarding the MRO mechanism for LTM PSCell handover or SCG LTM procedures need to be considered, including, for example, how to define the failure type of LTM PSCell handover when LTM PSCell handover failure, SCG LTM execution failure, or SCG failure occurs, and how to define ping-pong events when supporting subsequent LTM PSCell handovers; what information the network needs to report from the UE to perform MRO optimization for LTM PSCell handover-related configurations; how the network performs MRO detection or analysis (e.g., signaling exchange between MN and SN and between relevant CU and relevant DU); and how to enhance RA reporting for LTM PSCell handover procedures.

[0107] Currently, details regarding MRO mechanisms for failures in LTM PSCell handover or SCG LTM procedures have not been discussed. Embodiments of this disclosure aim to address the aforementioned issues. In cases where an LTM failure recovery mechanism is applied when a connection failure (e.g., SCG LTM execution failure or SCG failure) occurs, some embodiments of this application define failure types for LTM PSCell handover.

[0108] Some embodiments of this disclosure study the MRO mechanism of LTM PSCell handover or SCG LTM procedure. More specifically, in some embodiments of this disclosure, when an SCG failure occurs due to LTM PSCell handover, the MN or its CU may select a suitable PSCell; or, the MN's DU may select a suitable PSCell, for example, based on an optional request from the MN's CU, and then the MN's DU may indicate the selected suitable PSCell to the MN's CU. The MN's CU may indicate the suitable PSCell information to the SN or the SN's CU, and the SN may be a source SN, a target SN, or a candidate target SN. Then, the SN's CU may indicate the suitable PSCell information to the SN's DU. Alternatively, the SN's CU may select a suitable PSCell; or, the SN's DU may select a suitable PSCell, for example, based on an optional request from the SN's CU, and then the SN's DU may indicate the suitable PSCell information to the SN's CU. The suitable PSCell information may be the cell ID of the suitable PSCell, which may include a global cell identifier, the cell's tracking area code and / or physical cell identifier (PCI), and carrier frequency information. The DU in an SN can be a source DU, a target DU, or a candidate target DU. A source DU is a node that manages the source PSCell, a target DU is a node that manages the LTM target PSCell, and a candidate target DU is a node that manages the LTM candidate PSCell.

[0109] Some embodiments of this disclosure define failure types for SCG LTM that occur too late, too early, or to an incorrect PSCell. Furthermore, some embodiments of this disclosure define ping-pong problems in subsequent SCG LTM / LTM PSCell handover procedures if a subsequent PSCell handover procedure is executed.

[0110] In some embodiments of this disclosure, to perform MRO analysis and optimization for SCG failures caused by SCG LTM / LTM PSCell handover, the UE may store or report SCG LTM-related failure information (e.g., including indications of SCG failures caused by LTM PSCell handover, a list of LTM candidate PSCells, LTM PSCell handover related time information, etc.) to the MN or the CU of the MN. Then, the CU of the MN may send the SCG LTM-related failure information to the SN or the CU of the SN. Next, the CU of the SN may send the SCG LTM-related failure information to at least one DU of the SN (e.g., the source DU of the SN and / or the target DU of the SN and / or at least one candidate target DU). The SN may be a source SN, a target SN, or a candidate target SN.

[0111] In some embodiments of this disclosure, to avoid RACH conflicts, PRACH configurations for RA procedures triggered by early TA acquisition can be exchanged via the Xn or F1 interface. To help the network optimize RACH-related configurations for MCG LTM or SCG LTM, RA reports need to be enhanced to include LTM-related information (e.g., information related to early RACH procedures for early TA acquisition) or LTM-related information without RACH.

[0112] In some embodiments of this disclosure, the following operations may be performed for MRO detection or analysis of LTM PSCell switching:

[0113] - SN detects CU and indicates the occurrence of ping-pong in the subsequent LTM PSCell handover procedure to its corresponding DU (e.g., source DU, target DU, or at least one candidate target DU), and SN can be source SN, target SN, or candidate target SN.

[0114] - The CU or MN detection of MN and the CU of SN indicating the failure type of SCG LTM, SCG LTM, or SCG LTM to the wrong PSCell. Optionally, the CU or DU of SN can further verify whether the problem was detected by MN or the CU of MN, and SN can be the source SN, the target SN, or the candidate target SN.

[0115] - SN's CU detection and indicate the failure type of SCG LTM, SCG LTM, or SCGLTM to the erroneous PSCell to the corresponding DU; Optionally, the DU of the SN can further verify whether the problem is detected by the SN or the SN's CU, where the SN can be the source SN, the target SN, or a candidate target SN.

[0116] - Furthermore, the SN or its CU can detect whether it is an inappropriate LTM candidate PSCell provided by the SN or its CU, or an incorrect LTM candidate PSCell selected by the (candidate) target DU of the SN, or an incorrect LTM target PSCell selected at the source DU of the SN, which can be a source SN, a target SN, or a candidate target SN, and then the SN's CU can indicate the detected problem to the corresponding DU of the SN; optionally, the corresponding DU can further verify whether it is a problem detected by the CU; or

[0117] - The CU of the SN can forward SCG LTM-related failure information to the corresponding DU of the SN. The SN can be the source SN, the target SN, or a candidate target SN. Then, the corresponding DU detects the problem and indicates it to the CU of the SN.

[0118] Further details of embodiments of this disclosure will be described below in conjunction with the accompanying drawings.

[0119] Figure 1 This describes an example of a wireless communication system 100 according to aspects of this disclosure. The wireless communication system 100 may include one or more NEs 102, one or more UEs 104, and a core network (CN) 106. The wireless communication system 100 may support various radio access technologies. In some embodiments, the wireless communication system 100 may be a 4G network, such as an LTE network or an LTE-A network. In some other embodiments, the wireless communication system 100 may be an NR network, such as a 5G network, a 5G-A network, or a 5G Ultra Wideband (5G-UWB) network. In other embodiments, the wireless communication system 100 may be a combination of 4G and 5G networks, or other suitable radio access technologies, including IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), and IEEE 802.20. The wireless communication system 100 may support radio access technologies beyond 5G, such as 6G. In addition, the wireless communication system 100 can support technologies such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), or Code Division Multiple Access (CDMA).

[0120] One or more NEs 102 may be distributed across a geographical area to form a wireless communication system 100. One or more of the NEs 102 described herein may be, include, or be referred to as a network node, base station, network element, network function, network entity, radio access network (RAN), NodeB, eNodeB (eNB), next-generation NodeB (gNB), or other suitable terms. NEs 102 and UEs 104 may communicate via a communication link, which may be a wireless or wired connection. For example, NEs 102 and UEs 104 may perform wireless communication (e.g., receive signaling, transmit signaling) via a Uu interface.

[0121] NE 102 can provide a geographic coverage area that supports services for one or more UEs 104 within that geographic coverage area. For example, NE 102 and UE 104 can support wireless communication of signals associated with services (e.g., voice, video, packet data, messaging, broadcasting, etc.) based on one or more radio access technologies. In some embodiments, NE 102 can be mobile, for example, a satellite associated with a non-terrestrial network (NTN). In some embodiments, different geographic coverage areas 112 associated with the same or different radio access technologies can overlap, but different geographic coverage areas can be associated with different NEs 102.

[0122] One or more UEs 104 may be distributed across a geographical area of ​​the wireless communication system 100. UE 104 may include or be referred to as a remote unit, mobile device, wireless device, remote device, subscriber device, transmitter device, receiver device, or some other suitable term. In some implementations, UE 104 may be referred to as a unit, station, terminal, or client, and other instances thereof. Additionally or alternatively, UE 104 may be referred to as an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a Machine Type Communication (MTC) device, and other instances thereof.

[0123] UE 104 may be able to support direct wireless communication with other UE 104 via a communication link. For example, UE 104 may support direct wireless communication with another UE 104 via a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, communication link 114 may be referred to as a side link. For example, UE 104 may support direct wireless communication with another UE 104 via a PC5 interface.

[0124] NE 102 may support communication with CN 106 or with another NE 102 or both. For example, NE 102 may interface with other NE 102 or CN 106 via one or more backhaul links (e.g., S1, N2, N2, or network interfaces). In some embodiments, NE 102 may communicate directly with each other. In some other embodiments, NE 102 may communicate with each other or indirectly (e.g., via CN 106). In some embodiments, one or more NE 102 may include sub-components, such as access network entities, which may be instances of access node controllers (ANCs). The ANC may communicate with one or more UE 104s via one or more other access network transmitting entities (which may be referred to as radio heads, smart radio heads, or transmit-receive points (TRPs)).

[0125] CN 106 can support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. CN 106 can be an evolved packet core (EPC) or a 5G core (5GC), which may include control plane entities that manage access and mobility (e.g., a mobility management entity (MME), access and mobility management functions (AMF)) and user plane entities that route or interconnect packets to external networks (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)). In some implementations, the control plane entities may manage non-access stratum (NAS) functions of one or more UEs 104 served by one or more NEs 102 associated with CN 106, such as mobility, authentication, and bearer management (e.g., data bearers, signaling bearers, etc.).

[0126] CN 106 can communicate with the packet data network via one or more backhaul links (e.g., via S1, N2, N2, or another network interface). The packet data network may contain an application server. In some implementations, one or more UEs 104 can communicate with the application server. UE 104 can establish a session (e.g., a Protocol Data Unit (PDU) session, etc.) with CN 106 via NE 102. CN 106 can use the established session (e.g., an established PDU session) to route services (e.g., control information, data, etc.) between UE 104 and the application server. A PDU session may be an instance of a logical connection between UE 104 and CN 106 (e.g., one or more network functions of CN 106).

[0127] In the wireless communication system 100, NE 102 and UE 104 can use the resources of the wireless communication system 100 (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communication). In some embodiments, NE 102 and UE 104 may support different resource structures. For example, NE 102 and UE 104 may support different frame structures. In some embodiments, such as in 4G, NE 102 and UE 104 may support a single frame structure. In some other embodiments, such as in 5G and other suitable radio access technologies, NE 102 and UE 104 may support various frame structures (e.g., multiple frame structures). NE 102 and UE 104 may support various frame structures based on one or more parameter sets.

[0128] The wireless communication system 100 may support one or more parameter sets, and the parameter sets may include subcarrier spacing and cyclic prefixes. A first parameter set (e.g., μ=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a regular cyclic prefix. In some embodiments, the first parameter set (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one time slot per subframe. A second parameter set (e.g., μ=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a regular cyclic prefix. A third parameter set (e.g., μ=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a regular cyclic prefix or an extended cyclic prefix. A fourth parameter set (e.g., μ=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a regular cyclic prefix. A fifth parameter set (e.g., μ=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a regular cyclic prefix.

[0129] The time intervals of resources (e.g., communication resources) can be organized according to frames (also called radio frames). Each frame may have a duration, for example, 10 milliseconds (ms). In some embodiments, each frame may contain multiple subframes. For example, each frame may contain 10 subframes, and each subframe may have a duration, for example, 1 ms. In some embodiments, each frame may have the same duration. In some embodiments, each subframe of a frame may have the same duration.

[0130] Alternatively, the time intervals of resources (e.g., communication resources) can be organized according to time slots. For example, a subframe may contain a certain number (e.g., quantity) of time slots. The number of time slots in each subframe may also depend on one or more parameter sets supported in the wireless communication system 100. For example, the first, second, third, fourth, and fifth parameter sets (i.e., μ=0, μ=1, μ=2, μ=3, μ=4) associated with corresponding subcarrier intervals of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize one time slot per subframe, two time slots per subframe, four time slots per subframe, eight time slots per subframe, and 16 time slots per subframe, respectively. Each time slot may contain a certain number (e.g., quantity) of symbols (e.g., OFDM symbols). In some embodiments, the number (e.g., quantity) of time slots in a subframe may depend on the parameter set. For a conventional cyclic prefix, a time slot may contain 14 symbols. For an extended cyclic prefix (e.g., applicable to a 60 kHz subcarrier spacing), a time slot may contain 12 symbols. The relationship between the number of symbols per time slot for the regular cyclic prefix and the extended cyclic prefix, the number of time slots per subframe, and the number of time slots per frame may depend on the parameter set. It should be understood that references to the first parameter set (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and time slots.

[0131] In the wireless communication system 100, the electromagnetic (EM) spectrum can be divided into various categories, frequency bands, channels, etc., based on frequency or wavelength. For example, the wireless communication system 100 may support one or more operating frequency bands, such as frequency range names FR1 (410 MHz to 7.125 GHz), FR2 (24.25 GHz to 52.6 GHz), FR3 (7.125 GHz to 24.25 GHz), FR4 (52.6 GHz to 114.25 GHz), FR4a or FR4-1 (52.6 GHz to 71 GHz), and FR5 (114.25 GHz to 300 GHz). In some embodiments, NE 102 and UE 104 may perform wireless communication on one or more of the operating frequency bands. In some embodiments, FR1 may be used by NE 102 and UE 104, as well as other equipment or devices, for cellular communication services (e.g., control information, data). In some implementations, FR2 can be used by NE 102 and UE 104, as well as other equipment or devices, for short-range, high data rate capabilities.

[0132] FR1 may be associated with one or more parameter sets (e.g., at least three parameter sets). For example, FR1 may be associated with a first parameter set containing a 15 kHz subcarrier spacing (e.g., μ=0); a second parameter set containing a 30 kHz subcarrier spacing (e.g., μ=1); and a third parameter set containing a 60 kHz subcarrier spacing (e.g., μ=2). FR2 may be associated with one or more parameter sets (e.g., at least two parameter sets). For example, FR2 may be associated with a third parameter set containing a 60 kHz subcarrier spacing (e.g., μ=2); and a fourth parameter set containing a 120 kHz subcarrier spacing (e.g., μ=3).

[0133] Figure 2 An example of a UE 200 according to aspects of this disclosure is described. UE 200 may include a processor 202, a memory 204, a controller 206, and a transceiver 208. The processor 202, memory 204, controller 206, or transceiver 208, or various combinations thereof, or various components thereof, may be examples of components for performing the various aspects of this disclosure as described herein. These components may be coupled via one or more interfaces (e.g., operatively, communicatively, functionally, electronically, electrically).

[0134] Processor 202, memory 204, controller 206, or transceiver 208, or various combinations or components thereof, may be implemented in hardware (e.g., a circuit system). The hardware may be a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured or otherwise supporting components for performing the functions described in this disclosure.

[0135] Processor 202 may include intelligent hardware devices (e.g., a general-purpose processor, DSP, CPU, ASIC, FPGA, or any combination thereof). In some embodiments, processor 202 may be configured to operate memory 204. In some other embodiments, memory 204 may be integrated into processor 202. Processor 202 may be configured to execute computer-readable instructions stored in memory 204 to cause UE 200 to perform various functions of this disclosure.

[0136] Memory 204 may comprise volatile or non-volatile memory. Memory 204 may store computer-readable, computer-executable code containing instructions that, when executed by processor 202, cause UE 200 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as memory 204 or another type of memory. Computer-readable medium includes both non-transitory computer storage media and communication media, wherein the communication media includes any media that facilitates the transfer of a computer program from one place to another. Non-transitory storage media may be any available media accessible by a general-purpose or special-purpose computer.

[0137] In some embodiments, processor 202 and memory 204 coupled to processor 202 may be configured to cause UE 200 to perform one or more of the functions described herein (e.g., processor 202 executes instructions stored in memory 204). For example, processor 202 may be configured to perform one or more of the functions described herein (e.g., processor 202 executes instructions stored in memory 204). Figure 7 The disclosed examples support wireless communication at UE 200. For example, in response to the occurrence of a failure associated with an LTM PSCell handover procedure from the source PSCell to the target PSCell of UE 200, UE 200 may be configured to support components for storing failure information associated with the LTM PSCell handover procedure and components for transmitting failure information, wherein the failure includes at least one of SCG LTM execution failure or SCG failure.

[0138] For example, processor 202 may support wireless communication at UE 200, and UE 200 may be configured to support components for storing or transmitting RA reports, wherein the RA report includes at least one of the following: early RACH procedure related information; LTM related information without RACH; or RACH related information for early TA acquisition.

[0139] Controller 206 manages the input and output signals of UE 200. Controller 206 can also manage peripheral devices not integrated into UE 200. In some embodiments, controller 206 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some embodiments, controller 206 may be implemented as part of processor 202.

[0140] In some embodiments, UE 200 may include at least one transceiver 208. In other embodiments, UE 200 may have more than one transceiver 208. Transceiver 208 may represent a wireless transceiver. Transceiver 208 may include one or more receiver chains 210, one or more transmitter chains 212, or a combination thereof. The aforementioned components for receiving in processor 202 or for transmitting in processor 202 may be implemented via at least one transceiver 208.

[0141] Receiver chain 210 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, receiver chain 210 may include one or more antennas for receiving signals over the air or over a wireless medium. Receiver chain 210 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. Receiver chain 210 may include at least one demodulator configured to demodulate the received signal and obtain transmitted data by reversing the modulation technique applied during signal transmission. Receiver chain 210 may include at least one decoder for decoding the demodulated signal to receive the transmitted data.

[0142] Transmitter chain 212 can be configured to generate and transmit signals (e.g., control information, data, packets). Transmitter chain 212 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase shift keying (PSK) or quadrature amplitude modulation (QAM). Transmitter chain 212 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. Transmitter chain 212 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0143] Figure 3 An example of a processor 300 according to aspects of this disclosure is described. Processor 300 may be an example of a processor configured to perform various operations according to the examples described herein. Processor 300 may include a controller 302 configured to perform various operations according to the examples described herein. Processor 300 may optionally include at least one memory 304, which may be, for example, an L1 / L2 / L3 cache. Additionally or alternatively, processor 300 may optionally include one or more arithmetic logic units (ALUs) 306. One or more of these components may be electronically communicateable or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically).

[0144] Processor 300 may be a processor chipset and includes a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receive, acquire, retrieve, transmit, output, forward, store, determine, identify, access, write, read) according to the examples described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory native to the processor chipset (e.g., processor 300) or contained within the processor chipset (e.g., processor 300) or other memory (e.g., random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), static RAM (SRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase-change memory (PCM), and others)).

[0145] Controller 302 can be configured to manage and coordinate various operations of processor 300 (e.g., signaling, receiving, acquiring, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, and reading) to enable processor 300 to support various operations according to examples described herein. For example, controller 302 can operate as a control unit of processor 300, generating control signals that manage the operation of various components of processor 300. These control signals include enabling or disabling functional units, selecting data paths, initiating memory accesses, and coordinating operation timing.

[0146] Controller 302 may be configured to fetch (e.g., fetch, retrieve, receive) instructions from memory 304 and determine subsequent instructions to be executed to enable processor 300 to support various operations according to the examples described herein. Controller 302 may be configured to track the memory addresses of instructions associated with memory 304. Controller 302 may be configured to decode instructions to determine the operations to be performed and the operands involved. For example, controller 302 may be configured to interpret instructions and determine control signals to be output to other components of processor 300 to enable processor 300 to support various operations according to the examples described herein. Additionally or alternatively, controller 302 may be configured to manage data flow within processor 300. Controller 302 may be configured to control data transfers between registers, arithmetic logic unit (ALU), and other functional units of processor 300.

[0147] Memory 304 may include one or more caches (e.g., memory local to processor 300 or included in processor 300, or other memory such as RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc.). In some embodiments, memory 304 may reside within or on the processor chipset (e.g., local to processor 300). In some other embodiments, memory 304 may reside outside the processor chipset (e.g., remote from processor 300).

[0148] Memory 304 may store computer-readable, computer-executable code containing instructions that, when executed by processor 300, cause processor 300 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as system memory or another type of memory. Controller 302 and / or processor 300 may be configured to execute computer-readable instructions stored in memory 304 to cause processor 300 to perform various functions. For example, processor 300 and / or controller 302 may be coupled to or coupled to memory 304, and processor 300, controller 302, and memory 304 may be configured to perform the various functions described herein. In some instances, processor 300 may include multiple processors, and memory 304 may include multiple memories. One or more of the multiple processors may be coupled to one or more of the multiple memories, which may be individually or collectively configured to perform the various functions described herein.

[0149] One or more ALUs 306 may be configured to support various operations according to the examples described herein. In some embodiments, one or more ALUs 306 may reside within or on a processor chipset (e.g., processor 300). In some other embodiments, one or more ALUs 306 may reside outside the processor chipset (e.g., processor 300). One or more ALUs 306 may perform one or more calculations on data, such as addition, subtraction, multiplication, and division. For example, one or more ALUs 306 may receive input operands and an opcode that determines the operation to be performed. One or more ALUs 306 may be configured with various logic and arithmetic circuitry, including adders, subtractors, shifters, and logic gates, to process and manipulate data according to the operation. Alternatively, one or more ALU 306s may support logical operations such as AND, OR, XOR, NOR, and NAND, enabling one or more ALU 306s to handle conditional operations, comparisons, and bitwise operations.

[0150] Processor 300 may support wireless communication, as disclosed herein.

[0151] In some implementations, processor 300 may be configured to support components for performing operations on an SN, which may be a source SN, a target SN, or a candidate target SN. For example, in response to the occurrence of a failure associated with an LTMPSCell handover procedure from the UE's source PSCell to the target PSCell, processor 300 may be configured or operable to support components for obtaining failure information related to the LTMPSCell handover procedure, wherein the failure includes at least one of an SCG LTM execution failure or an SCG failure.

[0152] In some implementations, processor 300 may be configured to support components for performing operations on the SN, and the SN may be a source SN, a target SN, or a candidate target SN. Processor 300 may be configured or operable to support components for receiving from or transmitting to the MN PRACH configuration information for the RA procedure triggered by early TA acquisition.

[0153] In some implementations, processor 300 may be configured to support components for performing operations on a SN, whereby the SN may be a source SN, a target SN, or a candidate target SN. Processor 300 may be configured or operable to support components for receiving an RA report from a UE or MN, wherein the RA report contains at least one of the following: early RACH procedure-related information; LTM-related information without RACH; or RACH-related information for early TA acquisition.

[0154] In some implementations, processor 300 may be configured to support components for performing operations of the MN. For example, in response to the occurrence of a failure associated with an LTM PSCell handover procedure from the source PSCell to the target PSCell of the UE, processor 300 may be configured or operable to support components for performing at least one of the following: receiving failure information from the UE related to the LTM PSCell handover procedure; or obtaining information about the failure type of the failure, wherein the failure includes at least one of SCG LTM execution failure or SCG failure.

[0155] In some implementations, processor 300 may be configured to support components for performing operations of the MN. Processor 300 may be configured or operable to support components for transmitting to or receiving from the SN PRACH configuration information for triggering an RA procedure for early TA acquisition, and the SN may be a source SN, a target SN, or a candidate target SN.

[0156] In some implementations, processor 300 may be configured to support components for performing operations of the MN. Processor 300 may be configured or operable to support components for performing at least one of the following: receiving a random access (RA) report from a user equipment (UE); or transmitting an RA report to a SN, wherein the RA report contains at least one of the following: early RACH procedure-related information; LTM-related information without RACH; or RACH-related information for early TA acquisition, and the SN may be a source SN, a target SN, or a candidate target SN.

[0157] In some additional embodiments, processor 300 may be configured to support components for performing operations on the UE. For example, in response to the occurrence of a failure associated with an LTM PSCell handover procedure from the source PSCell to the target PSCell of the UE, processor 300 may be configured or operable to support components for storing failure information associated with the LTM PSCell handover procedure and for transmitting failure information, wherein the failure includes at least one of SCG LTM execution failure or SCG failure.

[0158] In some additional embodiments, processor 300 may be configured to support components for performing operations of the UE. Processor 300 may be configured or operable to support components for storing or transmitting random access (RA) reports, wherein the RA reports include at least one of the following: Early Random Access Channel (RACH) procedure-related information; L1 / L2 Triggered Mobility (LTM)-related information without RACH; or RACH-related information for early timing advance (TA) acquisition.

[0159] Those skilled in the art will understand that the components in the exemplary processor 300 can be changed; for example, some components in the exemplary processor 300 may be omitted or modified, or new components may be added to the exemplary processor 300, without departing from the spirit and scope of this disclosure. For instance, in some embodiments, the processor 300 may not include an ALU 306.

[0160] Figure 4 An example of NE 400 according to aspects of this disclosure is described. NE 400 may include a processor 402, a memory 404, a controller 406, and a transceiver 408. The processor 402, memory 404, controller 406, or transceiver 408, or various combinations thereof, or various components thereof, may be examples of components for performing the various aspects of this disclosure as described herein. These components may be coupled via one or more interfaces (e.g., operatively, communicatively, functionally, electronically, electrically).

[0161] Processor 402, memory 404, controller 406, or transceiver 408, or various combinations or components thereof, may be implemented in hardware (e.g., a circuit system). The hardware may be a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured or otherwise supporting components for performing the functions described in this disclosure.

[0162] Processor 402 may include intelligent hardware devices (e.g., a general-purpose processor, DSP, CPU, ASIC, FPGA, or any combination thereof). In some embodiments, processor 402 may be configured to operate memory 404. In some other embodiments, memory 404 may be integrated into processor 402. Processor 402 may be configured to execute computer-readable instructions stored in memory 404 to cause NE 400 to perform various functions of this disclosure.

[0163] Memory 404 may comprise volatile or non-volatile memory. Memory 404 may store computer-readable, computer-executable code containing instructions that, when executed by processor 402, cause NE 400 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as memory 404 or another type of memory. Computer-readable medium includes both non-transitory computer storage media and communication media, wherein the communication media includes any media that facilitates the transfer of a computer program from one place to another. Non-transitory storage media may be any available media accessible by a general-purpose or special-purpose computer.

[0164] In some implementations, processor 402 and memory 404 coupled to processor 402 may be configured to cause NE 400 to perform one or more of the functions described herein (e.g., processor 402 executes instructions stored in memory 404). For example, processor 402 may support wireless communication at NE 400 according to examples disclosed herein.

[0165] In some implementations, NE 400 may be an SN, and the SN may be a source SN, a target SN, or a candidate target SN. In response to the occurrence of a failure associated with the LTM PSCell handover procedure from the source PSCell of the UE to the target PSCell, NE 400 may be configured to support components for obtaining failure information related to the LTM PSCell handover procedure, wherein the failure includes at least one of SCGLTM execution failure or SCG failure.

[0166] In some implementations, NE 400 may be an SN, which may be a source SN, a target SN, or a candidate target SN, and NE 400 may be configured to support components for receiving or transmitting PRACH configuration information from or to the MN for RA procedures triggered by early TA acquisition.

[0167] In some implementations, NE 400 may be an SN, which may be a source SN, a target SN, or a candidate target SN, and NE 400 may be configured to support components for receiving random access (RA) reports from a UE or MN, wherein the RA report contains at least one of the following: early RACH procedure-related information; LTM-related information without RACH; or RACH-related information for early TA acquisition.

[0168] In some implementations, NE 400 may be MN. In response to the occurrence of a failure associated with the LTM PSCell handover procedure from the source PSCell to the target PSCell of the UE, NE 400 may be configured to support components for performing at least one of the following: receiving failure information associated with the LTM PSCell handover procedure from the UE; or obtaining information on the failure type of the failure, wherein the failure includes at least one of SCG LTM execution failure or SCG failure.

[0169] In some implementations, NE 400 may be MN, and NE 400 may be configured to support components for transmitting to or receiving from SN PRACH configuration information for RA procedures triggered by early TA acquisition, and SN may be source SN, target SN, or candidate target SN.

[0170] In some implementations, NE 400 may be MN, and NE 400 may be configured to support components for performing at least one of the following: receiving an RA report from the UE; or transmitting an RA report to the SN, wherein the RA report contains at least one of the following: early RACH procedure-related information; LTM-related information without RACH; or RACH-related information for early TA acquisition. SN may be a source SN, a target SN, or a candidate target SN.

[0171] Controller 406 manages the input and output signals of NE 400. Controller 406 can also manage peripheral devices not integrated into NE 400. In some embodiments, controller 406 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some embodiments, controller 406 may be implemented as part of processor 402.

[0172] In some embodiments, NE 400 may include at least one transceiver 408. In other embodiments, NE 400 may have more than one transceiver 408. Transceiver 408 may represent a wireless transceiver. Transceiver 408 may include one or more receiver chains 410, one or more transmitter chains 412, or a combination thereof. The aforementioned receiving or transmitting components in processor 402 may be implemented via at least one transceiver 408.

[0173] Receiver chain 410 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, receiver chain 410 may include one or more antennas for receiving signals over the air or over a wireless medium. Receiver chain 410 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. Receiver chain 410 may include at least one demodulator configured to demodulate the received signal and obtain transmitted data by reversing the modulation technique applied during signal transmission. Receiver chain 410 may include at least one decoder for decoding the demodulated signal to receive transmitted data.

[0174] Transmitter chain 412 can be configured to generate and transmit signals (e.g., control information, data, packets). Transmitter chain 412 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase shift keying (PSK) or quadrature amplitude modulation (QAM). Transmitter chain 412 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. Transmitter chain 412 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0175] Those skilled in the art will understand that components in the exemplary NE 400 can be changed; for example, some components in the exemplary NE 400 can be omitted or modified, or new components can be added to the exemplary NE 400, without departing from the spirit and scope of this disclosure. For instance, in some embodiments, the NE 400 may not include the controller 406.

[0176] Figure 5A A schematic diagram illustrating a mobility scenario within a CU and DU according to aspects of this disclosure. Figure 5AThe wireless communication system includes a DU, UEs (e.g., UE 101A), and several access nodes (e.g., access node 102A and access node 103A). Access nodes 102A and 103A are controlled by the DU and provide services to UEs within PSCell #1 and PSCell #2, respectively. Even Figure 5A There may be only one UE and two access nodes in the system, but those skilled in the art should recognize that any number of UEs and access nodes may be included in a wireless communication system.

[0177] exist Figure 5A In this scenario, UE 101A is moving from PSCell #1 to PSCell #2 and can execute an LTM cell handover procedure from PSCell #1 to PSCell #2. This is an LTM PSCell handover procedure performed between different cells within a DU. This scenario can be referred to as intra-CU / intra-DU mobility. It can be abbreviated as intra-DU mobility.

[0178] Figure 5B A schematic diagram illustrating a scenario of mobility between DUs within a CU according to aspects of this disclosure. Figure 5B The wireless communication system includes a CU, UEs (e.g., UE 101B), and several DUs (e.g., DU #1 and DU #2). DU #1 and DU #2 are controlled by the CU and provide services to the UEs within PSCell #A and PSCell #B, respectively. Even Figure 5B There may be only one UE and two DUs in the system, but those skilled in the art should recognize that any number of UEs and DUs may be included in a wireless communication system.

[0179] exist Figure 5B In this scenario, UE 101B is moving from PSCell #A to PSCell #B and can execute an LTM PSCell handover procedure from PSCell #A to PSCell #B. This LTM PSCell handover procedure is performed between different cells belonging to different DUs but within the same CU. This scenario can be referred to as intra-CU inter-DU mobility. This scenario can be simply referred to as inter-DU mobility.

[0180] Figure 5C A schematic diagram illustrating a scenario of inter-CU mobility according to aspects of this disclosure. Figure 5C The wireless communication system includes several CUs (e.g., CU #1 and CU #2), UEs (e.g., UE 101C), and several DUs (e.g., DU #A and DU #B). DU #A is controlled by CU #1 and provides service to the UE within PSCell #X. DU #B is controlled by CU #2 and provides service to the UE within PSCell #Y. Even Figure 5C There may be only one UE, two DUs and two CUs, but those skilled in the art should recognize that any number of UEs, DUs and CUs may be included in a wireless communication system.

[0181] exist Figure 5C In this scenario, UE 101C is moving from PSCell #X to PSCell #Y and can execute an LTM PSCell handover procedure from PSCell #X to PSCell #Y. This LTM PSCell handover procedure is performed between different cells of different DUs belonging to different CUs. This scenario can be referred to as inter-CU mobility.

[0182] Figure 6 This diagram illustrates an LTM procedure between DUs and within a CU within an NR based on aspects of this disclosure. The LTM procedure between DUs and within a CU is used when a UE moves from one DU to another within the same CU during NR operations for LTM.

[0183] exist Figure 6 In an embodiment, the wireless communication system includes a UE, a source DU (which may also be referred to as a serving DU, which serves the UE before the LTM procedure is triggered), a target DU, and one or more candidate DUs (which in Figure 6 The source DU and target DU, or one or more candidate DUs, are located within the CU. The source DU and target DU, or one or more candidate DUs, are located within the SN. The CU is the CU of the SN. The UE is moving from the source DU to one of the target DUs or one or more candidate DUs. The source DU can manage (or control) the UE's serving PSCell and one or more source PSCells. The serving PSCell and one or more source PSCells are considered to be within the source DU. Each candidate DU can manage one or more LTM candidate PSCells, and one or more candidate PSCells are considered to be within each candidate DU. One of the one or more candidate DUs manages the LTM candidate PSCell to which the UE can switch. In some embodiments, the LTM candidate PSCell to which the UE switches may be referred to as the "LTM candidate target PSCell". An LTM candidate PSCell is referred to as the LTM target PSCell when it is selected by the network as the target PSCell for LTM or indicated in the LTM cell handover MAC CE. The candidate DU that manages or controls the LTM candidate PSCell is then referred to as the target DU; that is, the LTM target PSCell is managed by the target DU, and the LTM candidate PSCell is managed by the candidate target DU.

[0184] In operation 601, the UE sends a measurement report message containing measurements of neighboring cells to the source DU. The source DU sends a UL RRC message transmission message to the CU conveying the received measurement report message.

[0185] In operation 602, the CU determines to start the LTM configuration.

[0186] In operation 603, the CU sends a UE context setting request message containing a target candidate PSCell ID to the candidate DU. The CU indicates the source DU ID and requests PRACH resources from the candidate DU.

[0187] In operation 604, if the candidate DU accepts the LTM configuration request, it responds with a UE context setting response message that includes the generated lower-layer RRC configuration (e.g., transmit configuration indication (TCI) state configuration and RACH configuration) and the RS configuration of the accepted LTM candidate PSCell.

[0188] In operation 605, the CU sends a UE context modification request message to the source DU, which contains the collected RS configuration, TCI state configuration and RACH configuration of the accepted LTM candidate PSCell in other DUs.

[0189] In operation 606, the source DU responds with a UE context modification response message, which may include the source cell, the RS configuration of the prepared LTM candidate PSCell, and the generated CSI resource configuration.

[0190] In operation 607, the CU sends a UE context modification request message to the candidate DU, which contains the cell ID of the prepared LTM candidate PSCell and the associated RS configuration for each LTM candidate PSCell in the other candidate DUs. In some cases, the source cell can be configured as an LTM candidate PSCell.

[0191] In operation 608, the candidate DU responds with a UE context modification response message containing the generated CSI resource configuration.

[0192] In operation 609, the CU sends a DL RRC message transmission message to the source DU, which contains the generated RRC reconfiguration message with LTM configuration.

[0193] In operation 610, the source DU forwards the received RRC reconfiguration message to the UE.

[0194] In operation 611, the UE responds to the source DU with an RRC reconfiguration complete message.

[0195] In operation 612, the source DU forwards the RRC reconfiguration complete message to the CU via the UL RRC message transmission message.

[0196] In operation 613, the UE sends the lower-layer measurement results, such as L1 measurement results, to the source DU.

[0197] In operation 614, the source DU decides to perform LTM on the LTM candidate target PSCell.

[0198] In operation 615, the source DU sends an LTM command to the UE.

[0199] In operation 616, the source DU sends an LTM cell change notification message to the CU to instruct the UE to initiate an LTM command containing the target PSCell ID and selected beam information.

[0200] In operation 617, the CU sends the target PSCell ID and selected beam information to the target DU.

[0201] In operation 618, the target DU detects the access of the UE.

[0202] In operation 619, the target DU sends an access success message with the target PSCell ID to the CU.

[0203] In operation 620 (optional), the CU may send a UE context release command message to the source DU to release the resources of the prepared PSCell.

[0204] In operation 621 (optional), the source DU responds with a UE context release complete message.

[0205] Some embodiments of this disclosure relate to LTM procedures within a DU and CU within an NR, wherein a serving or source PSCell and one or more LTM candidate PSCells are considered to be in the same DU. The wireless communication system for an LTM procedure within a DU includes a UE, a DU (which may also be referred to as a source or serving DU, a target DU, or a candidate DU), and a CU. The source DU is within the CU. That is, with... Figure 6 Unlike the source DU and target DU or candidate DU in inter-DU LTM, the intra-DU LTM procedure involves only one DU, meaning the source DU and the target DU or candidate DU are the same node. In the intra-DU LTM procedure, the messages transmitted between the DU and CU are similar to the messages transmitted between the source DU, target DU, or one or more candidate DUs and CU in the inter-DU LTM procedure, such as... Figure 6 The embodiments are described therein.

[0206] In some embodiments of this disclosure, LTM PSCell handover failure, SCG LTM execution failure (i.e., supervisory timer T304 expiring), or SCG failure (e.g., RLF) may occur during the LTM PSCell handover procedure or during the SCG LTM procedure (e.g., a PSCell change triggered by the LTM PSCell handover MAC CE). Upon SCG failure, the UE may transmit an SCG failure information message to the MN.

[0207] Figure 7 A flowchart illustrating a method related to an LTM PSCell handover procedure according to aspects of this disclosure is provided. The operation of the method can be implemented by the UE, as described herein. In some embodiments, the UE can execute a set of instructions to control functional elements of the UE to perform the described functions. In some embodiments, aspects operating 702 and 704 can be provided by reference to... Figure 2 and 5A Perform on UE 200, UE 101A, UE 101B or UE 101C as described in 5C. Each of operations 702 and 704 may be performed according to the examples described herein.

[0208] In operation 702, in response to the occurrence of a failure associated with the LTM PSCell handover procedure from the source PSCell to the target PSCell of the UE, the method may include having the UE store failure information related to the LTM PSCell handover procedure. The failure includes at least one of SCG LTM execution failure or SCG failure.

[0209] In operation 704, the method may include failure information transmitted by the UE. In some implementations, the failure information (referred to as "failure information #1") includes at least one of the following:

[0210] (1) Information about the source PSCell;

[0211] (2) Information about the PSCell where the failure occurred;

[0212] (3) Information about the selected beam in the target PSCell;

[0213] (4) Information about one or more adjacent cells;

[0214] (5) L1 or L3 measurement results of the source PSCell;

[0215] (6) The L1 or L3 measurement results of the PSCell where the failure occurred;

[0216] (7) L1 or L3 measurement results of adjacent cells;

[0217] (8) Information indicating whether the neighboring cells included in the L1 or L3 measurement results are LTM candidate PSCells;

[0218] (9) Indicates information about failures that occurred during the LTM PSCell switching procedure;

[0219] (10) Information regarding at least one LTM candidate PSCell configured for the LTM PSCell switching procedure;

[0220] (11) Cell configuration information of at least one LTM candidate PSCell;

[0221] (12) A set of Channel State Information (CSI) resources for LTM PSCell handover procedures;

[0222] (13) Reference configuration for LTM PSCell switching procedure;

[0223] (14) The time elapsed between the receipt of the LTM PSCell handover command and the receipt of the most recent RRC reconfiguration message of the LTM PSCell handover procedure;

[0224] (15) The time elapsed between the receipt of the LTM PSCell switching command and the occurrence of the failure;

[0225] (16) The time elapsed between the occurrence of the failure and the UE transmitting the failure message;

[0226] (17) TA value of SCG LTM without RACH; or

[0227] (18) TA value derived from the early RACH procedure used for early TA acquisition.

[0228] In embodiments of this disclosure, information about a cell (e.g., information about a source PSCell, information about a PSCell where a failure occurred, information about one or more neighboring cells) may be a cell ID, which may include a global cell identifier, the cell’s tracking area code and / or physical cell identifier (PCI) and carrier frequency information.

[0229] It should be noted that Figure 7 The methods described herein describe possible implementation schemes, and the operations and steps may be rearranged or otherwise exempted or modified, and other implementation schemes are possible without departing from the spirit and scope of this disclosure.

[0230] Some embodiments of this disclosure relate to a method associated with an LTM PSCell handover procedure implemented by a network node, as described herein. In some embodiments, the network node may be an SN (e.g., the SN may be a source SN, a target SN, or a candidate target SN), and may execute a set of instructions to control the functional elements of the SN to perform the described functions as follows.

[0231] In some implementations, in response to the occurrence of a failure associated with an LTM PSCell handover procedure from the source PSCell to the target PSCell of the UE, the method may include obtaining failure information associated with the LTM PSCell handover procedure from the SN, wherein the failure includes at least one of SCG LTM execution failure or SCG failure.

[0232] In some implementations, the SN or the CU of the SN may perform one of the following:

[0233] (1) Receive failure type information from MN, where the failure type is detected by MN; or

[0234] (2) Failure type of detection failure.

[0235] In the implementation scheme, the SN or its CU can verify the failure type after receiving information about the failure type from the MN. If the failure type is correct, the SN or CU can transmit a message to the MN indicating that the failure type detected by the MN is correct (represented as "Message #1"). If the failure type detected by the MN is incorrect, the SN or CU can transmit a message to the MN indicating that the failure type detected by the MN is incorrect (represented as "Message #2").

[0236] In some implementations, the CU of the SN may transmit at least one of the following to at least one DU of the SN:

[0237] (1) Failure information related to the LTM PSCell switching procedure;

[0238] (2) Information about the failure type received from MN; or

[0239] (3) Information on the failure type detected by the CU of the SN.

[0240] Next, at least one DU of the SN can detect the failure type of the failure or verify the failure type detected by the MN or by the CU of the SN.

[0241] In one implementation, at least one DU of the SN can transmit to the CU of the SN the failure type detected by the at least one DU. In another implementation, if the failure type detected by the MN or the CU is correct, then at least one DU can transmit to the CU information indicating that the failure type detected by the MN or the CU is correct. In yet another implementation, if the failure type detected by the MN or the CU is incorrect, then at least one DU can transmit to the CU information indicating that the failure type detected by the MN or the CU is incorrect, or at least one DU can transmit to the CU information indicating the failure type verified by at least one DU of the SN.

[0242] In some implementations, the SN or the CU of the SN may indicate to the MN any of the following:

[0243] (1) Failure type detected by SN or CU;

[0244] (2) Failure type verified by SN or CU;

[0245] (3) The failure type detected by at least one DU of the SN; or

[0246] (4) Failure type verified by at least one DU of SN.

[0247] In some implementations, the SN or the CU of the SN may transmit to the MN at least one of the following: (1) a message indicating that the failure type detected by the MN is an error; or (2) a message indicating that the failure type detected by the MN is correct.

[0248] In some implementations, the failure type includes at least one of the following:

[0249] (1) Failure type (represented as "failure type #1"), which is defined as "too late SCG LTM", in which the UE has received the configuration information of the LTM PSCell handover procedure, but the SCG failure occurs after the UE has stayed in the source PSCell for a certain period of time or before the LTM PSCell handover command that triggers the LTM PSCell handover procedure to the UE, and the appropriate PSCell different from the source PSCell is found based on the layer 1 (L1) or layer 3 (L3) measurement results reported by the UE. "Too late SCG LTM" can be named "too late LTM PSCell handover" or "too late LTM for SCG" or other names;

[0250] (2) Failure type (represented as "Failure Type #2"), which is defined as "Premature SCG LTM", where the SCG failure occurs shortly after the successful completion of the LTM PSCell handover from the source PSCell to the target PSCell or the SCG LTM execution fails, and the source PSCell is a suitable PSCell based on the L1 or L3 measurement results reported from the UE. "Premature SCG LTM" may be named "Premature LTM PSCell Handover" or "Premature LTM for SCG" or other names; or

[0251] (3) Failure type (referred to as “Failure type #3”), which is defined as “SCG LTM to the wrong PSCell”, where the SCG failure occurs shortly after the successful completion of the LTM PSCell handover from the source PSCell to the target PSCell or the SCGLTM execution failure occurs, and the appropriate PSCell, which is different from the source PSCell and the target PSCell, is found based on the L1 or L3 measurement results reported from the UE. “SCG LTM to the wrong PSCell” may be named “LTM PSCell handover to the wrong PSCell” or “LTM for SCG to the wrong PSCell” or other names.

[0252] In some implementations, in response to a failure, the SN or its CU may receive information about the appropriate PSCell. For example, the appropriate PSCell is selected by the MN, and information about the appropriate PSCell is received from the MN. In another implementation, the SN's CU may transmit the information about the appropriate PSCell received from the MN to at least one of the SN's DUs.

[0253] In some other embodiments, in response to a failure, the SN or its CU may select a suitable PSCell. In one embodiment, the suitable PSCell is selected by the CU. In another embodiment, the suitable PSCell is selected by at least one DU of the SN, and then the at least one DU may transmit information about the suitable PSCell to the CU. In some embodiments, the CU of the SN requests at least one DU of the SN to select a suitable PSCell. In some embodiments, the SN or its CU may transmit information about the suitable PSCell to the MN. The information about the suitable PSCell may be the cell ID of the suitable PSCell, which may include a global cell identifier, the cell's tracking area code and / or physical cell identifier (PCI), and carrier frequency information.

[0254] In some implementations, the failure type further includes at least one of the following:

[0255] (1) Failure type (referred to as "Failure type #4"), wherein the appropriate PSCell selected in response to the occurrence of failure is not one of a set of LTM candidate PSCells (referred to as "LTM candidate PSCell set #1") provided by the CU of the SN to at least one DU of the SN;

[0256] (2) Failure type (referred to as "Failure Type #5"), wherein the suitable PSCell is one of the LTM candidate PSCell groups #1, but not one of the LTM candidate PSCell groups (referred to as "LTM candidate PSCell group #2") selected by at least one DU; or

[0257] (3) Failure type (referred to as "failure type #6"), where the appropriate PSCell is one of the LTM candidate PSCell groups #2.

[0258] In some implementations, the SN or the CU of the SN can detect whether the failure type is one of failure type #4, failure type #5, and failure type #6.

[0259] If the failure type is failure type #4, then the SN or the CU of the SN can determine that the LTM candidate PSCell group #1 provided by the SN or the CU of the SN is inappropriate. In an implementation, the SN or the CU of the SN can transmit information to at least one DU of the MN or the SN indicating that the LTM candidate PSCell group #1 provided by the SN or the CU of the SN is inappropriate.

[0260] If the failure type is failure type #5, then the CU of the SN can detect that one or more erroneous LTM candidate PSCells have been selected by at least one DU; or the CU of the SN can transmit information to at least one DU indicating that one or more erroneous LTM candidate PSCells have been selected by at least one DU (referred to as "information #3"). In an implementation, at least one DU can verify the failure type or whether one or more erroneous LTM candidate PSCells have been selected by at least one DU.

[0261] In some implementations, at least one DU may transmit one of the following to the CU:

[0262] (1) Information indicating that CU has performed a correct check on information #3;

[0263] (2) Instructs CU to perform error detection regarding information #3; or

[0264] (3) Information on the failure type detected or verified by at least one DU.

[0265] In some implementations, the SN or the CU of the SN may transmit information about the failure type detected or verified by the SN or at least one DU to the MN.

[0266] If the failure type is failure type #6, then the CU of the SN can detect that the source DU of the SN has selected the wrong LTM target PSCell; or the CU can transmit a message to the source DU indicating that the source DU has selected the wrong LTM target PSCell (referred to as "message #4").

[0267] In some implementations, the source DU can verify the failure type or whether the source DU selected the erroneous LTM target PSCell. The source DU can then send one of the following to the CU:

[0268] (1) The CU was instructed to perform a correct check on information #4;

[0269] (2) Instructs CU to perform error detection regarding information #4; or

[0270] (3) Information on the failure type detected or verified by the source DU.

[0271] In some implementations, the SN or the CU of the SN may transmit information about the failure type detected or verified by the SN or the source DU to the MN.

[0272] In some implementations, the CU of the SN can transmit at least one of a failure message or a suitable PSCell message to at least one DU of the SN. The at least one DU is then configured to detect the failure type.

[0273] If the failure type is failure type #4, then at least one DU can detect that the LTM candidate PSCell group #1 provided by the CU is inappropriate; or at least one DU can transmit to the CU a message indicating that the LTM candidate PSCell group #1 provided by the CU is inappropriate (referred to as "message #5").

[0274] If the failure type is failure type #5, then at least one DU can detect that one or more erroneous LTM candidate PSCells have been selected by at least one DU; or at least one DU can transmit to the CU a message indicating that one or more erroneous LTM candidate PSCells have been selected by at least one DU (referred to as "message #6").

[0275] If the failure type is failure type #6, then the source DU can detect that the source DU has selected the wrong LTM target PSCell; or the source DU can transmit a message to the CU indicating that the source DU has selected the wrong LTM target PSCell (represented as "message #7").

[0276] In some implementations, the SN or the CU of the SN may transmit information #5, information #6 or information #7 to the MN.

[0277] In some implementations, in order to obtain failure information, the SN or its CU can independently derive the failure information or receive failure information stored or transmitted by the UE (e.g., such as...). Figure 7 The failure information described in the embodiments is #1). In the implementation, the CU of the SN may transmit failure information to at least one DU after receiving failure information.

[0278] In some implementations, the SN or its CU can detect whether a ping-pong event has occurred. In other implementations, the SN or at least one DU of the SN can detect whether a ping-pong event has occurred. For a ping-pong event, after a successful LTM PSCell handover from PSCell (e.g., PSCell #1) to another PSCell (e.g., PSCell #2), the UE hands back to PSCell #1 within a predefined period or the UE successfully performs another LTM PSCell handover from PSCell #2 back to PSCell #1.

[0279] In one implementation, the CU of the SN can transmit information indicating the occurrence of a ping-pong event to at least one DU. In another implementation, at least one DU of the SN can transmit information indicating the occurrence of a ping-pong event to the CU of the SN.

[0280] In some implementations, ping-pong events are detected based on: (1) the UE’s historical information; (2) the duration between receiving two LTM cell change notification messages on the same PSCell; or (3) the duration between receiving two access success messages on the same PSCell.

[0281] In some implementations, at least one DU of the SN is a source DU, a target DU, and / or at least one candidate target DU.

[0282] Some embodiments of this disclosure relate to a method associated with an LTM PSCell handover procedure implemented by a network node, as described herein. In some embodiments, the network node may be an MN, and may execute a set of instructions to control the functional elements of the MN to perform the described functions as follows.

[0283] In some implementations, in response to the occurrence of a failure associated with an LTM PSCell handover procedure from the source PSCell to the target PSCell of the UE, the method may include the MN performing at least one of the following: receiving failure information related to the LTM PSCell handover procedure from the UE; or obtaining information about the type of failure. The failure includes at least one of SCG LTM execution failure or SCG failure.

[0284] In the implementation scheme, the MN may transmit failure information to the SN (e.g., such as...). Figure 7 The failure information #1 described in the embodiments, and SN can be source SN, target SN or candidate target SN.

[0285] In some implementations, to obtain information about the type of failure, MN may perform at least one of the following:

[0286] (1) Detection failure types;

[0287] (2) Receive failure type information from SN; or

[0288] (3) Transmit information about the failure type detected by the MN to the SN; optionally, the SN may verify the failure type detected by the MN.

[0289] In some implementations, the MN may receive one of the following from the SN:

[0290] (1) The information indicates that the failure type detected by MN is correct;

[0291] (2) A message indicating that the failure type detected by MN is an error;

[0292] (3) Information indicating the type of failure detected by the SN; or

[0293] (4) Information indicating the type of failure verified by the SN.

[0294] In some implementations, the failure type includes at least one of the following described above: failure type #1, failure type #2, failure type #3, failure type #4, failure type #5, or failure type #6.

[0295] In some implementations, in response to a failure, the MN may select a suitable PSCell and transmit information about the suitable PSCell to the SN. In some implementations, the CU of the MN or at least one DU of the MN may select a suitable PSCell. In one instance, the CU of the MN requests at least one DU of the MN to select a suitable PSCell. In some implementations, the CU of the MN transmits information about the suitable PSCell to the SN.

[0296] In some implementations, the MN may receive information about the appropriate PSCell from the SN, wherein the appropriate PSCell is selected by the SN.

[0297] In some implementations, the MN may receive one of the following from the SN:

[0298] (1) It is inappropriate information to indicate a set of LTM candidate PSCells provided by the SN or the CU of the SN;

[0299] (2) Information indicating that one or more erroneous LTM candidate PSCells are selected by SN or at least one DU of SN;

[0300] (3) Information indicating that the LTM target PSCell was selected by the SN or the source DU of the SN;

[0301] (4) Information on the failure type detected or verified by at least one DU of the SN;

[0302] (5) Information on the failure type detected or verified by the source DU of the SN; or

[0303] (6) Information on the failure type detected or verified by SN.

[0304] The following describes specific embodiments of the flowcharts shown and illustrated above, namely, embodiments 1 to 4.

[0305] Example 1 (Definition of Stage 2 in Failure or Ping-Pong Situation)

[0306] Generally, there is a possibility that SCG LTM procedures and MCG LTM procedures can coexist. If so, then coordination is required between the maximum number of candidates between the MN and the SN (e.g., the SN can be the source SN, the target SN, or a candidate target SN).

[0307] In Example 1, if the MCG LTM is triggered first, then the MN may indicate at least one of the following to the SN (e.g., the SN may be a source SN, a target SN, or a candidate target SN):

[0308] (1) The maximum number of LTM configurations to be prepared;

[0309] (2) The maximum number of LTM candidate PCells prepared;

[0310] (3) The maximum number of LTM configurations to be prepared; or

[0311] (4) The maximum number of LTM candidate PSCells to be prepared.

[0312] In Example 1, if the SCG LTM procedure is triggered first, then the SN (e.g., the SN may be a source SN, a target SN, or a candidate target SN) may indicate at least one of the following to the MN:

[0313] (1) The maximum number of LTM configurations to be prepared;

[0314] (2) The maximum number of LTM candidate PSCells prepared;

[0315] (3) The maximum number of LTM configurations to be prepared; or

[0316] (4) The maximum number of LTM candidate PCells to be prepared.

[0317] In some embodiments, MCG release or SCG release has a higher priority than the SCG LTM procedure, and RRC rebuild / set / restore has a higher priority than the SCG LTM procedure. When the UE has stored an LTM candidate PSCell configuration, the UE can also execute any L3 PSCell change command sent by the network. The network avoids any problems caused by conflicts between LTM PSCell handover and L3 PSCell change, for example, avoiding the simultaneous sending of LTM PSCell handover commands and L3 PSCell change commands.

[0318] In cases where the L3 PSCell change is triggered earlier than the SCG LTM procedure (the L3 PSCell change is triggered before the SCG LTM procedure is triggered), the L3 PSCell change has high priority. In cases where the SCG LTM procedure is triggered earlier than the L3 PSCell change (e.g., the gNB-CU receives an LTM notification message, such as an LTM CELL CHANGE NOTIFICATION message, from the gNB-DU before the L3 PSCell change is triggered), the SCG LTM procedure has high priority. In cases where the SCG LTM procedure and the PSCell change are triggered almost simultaneously, the SN's gNB-DU responds by modifying the UE context with a failure message indicating that the SCG LTM has high priority, thus causing the L3 PSCell change to fail.

[0319] In an SCG LTM procedure (e.g., a PSCell change triggered by an LTM cell handover MAC CE), an LTM PSCell handover failure, an SCG LTM execution failure (i.e., the supervisory timer T304 expires), or an RLF may occur. After a connection failure, the UE can make SCG LTM-related failure information available to the MN, for example, by storing or reporting the SCG LTM-related failure information in a message. The message can be an existing message (e.g., an SCG failure message or other messages) or in a newly introduced message. For example, after the MN receives the SCG LTM-related failure information, the UE can, for example, send the SCG LTM-related failure information to the MN via an SCG failure information message. In different embodiments, the following two options may exist: Option #1 and Option #2.

[0320] Option #1: MN can select a suitable PSCell, for example, based on L1 or L3 measurements from the UE. For example, the following implementations may exist:

[0321] (1) The CU of MN or MN can, for example, select a suitable PSCell as the target PSCell for L3 PSCell change based on L3 measurement results; or

[0322] (2) The CU of MN or MN can, for example, select a suitable PSCell as the target PSCell for LTM PSCell switching based on L1 measurement results; or

[0323] (3) At least one DU of MN may select a suitable PSCell (e.g., as the LTM target PSCell for LTM PSCell handover, based on L1 measurement results). Optionally, CU of MN may instruct at least one DU of MN to select a suitable PSCell. Then, at least one DU of MN may indicate the information of the suitable PSCell (e.g., suitable PSCell ID, which may include global cell identifier, cell tracking area code and / or physical cell identifier (PCI) and carrier frequency information) to CU of MN.

[0324] In option #1, the MN may indicate the appropriate PSCell information (e.g., the appropriate PSCell ID) to the SN, or the CU of the MN may indicate the appropriate PSCell information (e.g., the appropriate PSCell ID) to the CU of the SN. Then, the CU of the SN may indicate the appropriate PSCell information (e.g., the appropriate PSCell ID) to the DU of the SN (e.g., the source DU of the SN, the target DU of the SN, or at least one candidate target DU of the SN).

[0325] In embodiments of this disclosure, the SN is the node that serves the UE during the final initialization of the SCG LTM procedure or the LTM PSCell handover procedure, or the node that triggers the SCG LTM procedure or the LTM PSCell handover procedure. For example, the SN may be a source SN, a target SN, or a candidate target SN.

[0326] Option #2: The MN can send SCG LTM-related failure information to the SN. The SN can then select a suitable PSCell, for example, based on L1 or L3 measurement results from the UE. For example, the following implementation may exist:

[0327] (1) The SN or the CU of the SN can, for example, select a suitable PSCell as the target PSCell for L3 PSCell change based on the L3 measurement results; or

[0328] (2) The SN or its CU can, for example, select a suitable PSCell as the target PSCell for LTM PSCell handover based on L1 measurement results. Then, the SN's CU can indicate suitable PSCell information (e.g., suitable PSCell ID, which may include the global cell identifier, the cell's tracking area code, and / or the physical cell identifier (PCI) and carrier frequency information) to at least one DU of the SN (e.g., the SN's source DU, the SN's target DU, or at least one candidate target DU of the SN); or

[0329] (3) At least one DU of the SN (e.g., a source DU of the SN, a target DU of the SN, or at least one candidate target DU of the SN) may select a suitable PSCell (e.g., as the target PSCell for LTM PSCell handover, based on L1 measurement results). Optionally, the CU of the SN may instruct at least one DU of the SN to select a suitable PSCell. Then, at least one DU of the SN may indicate the information of the suitable PSCell (e.g., the suitable PSCell ID, which may include the global cell identifier, the cell's tracking area code and / or the physical cell identifier (PCI) and carrier frequency information) to the CU of the SN.

[0330] In option #2, the SN or the CU of the SN may indicate the appropriate PSCell information (e.g., the appropriate PSCell ID) to the MN or the CU of the MN. Then, the CU of the MN may indicate the appropriate PSCell information (e.g., the appropriate PSCell ID) to at least one DU of the MN (e.g., the source DU of the MN, the target DU of the MN, or at least one candidate target DU of the MN).

[0331] In some embodiments of this disclosure, the MN may perform an initial analysis to identify the node that caused the failure. The MN may use an SCG failure information reporting procedure to verify whether the SCG LTM within the SN has been triggered in the last serving SN and to store the SCG failure information within the time required to receive a possible response from the last serving SN. If the failure was caused by the source SN, then the MN then forwards the SCG failure information to the source SN. The node responsible for the last LTM PSCell handover (e.g., the source SN, the last serving SN, the target SN, the candidate target SN, or the MN) performs a final root cause analysis.

[0332] In some embodiments of this disclosure, one of the self-optimization functions for the LTM PSCell switching procedure or the SCG LTM procedure is to detect failures due to excessively late SCG LTM, excessively early SCG LTM, or SCG LTM to an incorrect PSCell. Failure types may also be named "problem type," "event type," or "condition type," etc. Failure types can be defined as follows:

[0333] - Too Late SCG LTM: The UE receives the configuration for the SCG LTM procedure, but the SCG failure occurs after the UE has been in the serving PSCell for a long period of time, or after LTM for SCG has been configured, but the SCG RLF occurs before the MAC CE for initiating / triggering the LTM PSCell handover to the UE; the appropriate different PSCell is found based on the L1 or L3 measurement results reported by the UE. "Too Late SCG LTM" can also be named "Too Late LTM PSCell Handover", "Too Late LTM for SCG", or others.

[0334] - Premature SCG LTM: SCG failure occurs shortly after a successful LTM PSCell handover from the source PSCell to the target PSCell, or during the SCG LTM execution procedure if the LTM PSCell handover fails or the SCG LTM execution fails; the source PSCell is still a suitable PSCell based on L1 or L3 measurements reported from the UE. "Premature SCG LTM" may also be named "Premature LTM PSCell Handover," "Premature LTM for SCG," or others.

[0335] - SCG LTM to an incorrect PSCell: SCG failure occurs shortly after a successful LTM PSCell handover from the source PSCell to the target PSCell, or during an LTM PSCell handover failure / SCG LTM execution failure. The appropriate PSCell, different from the source or target PSCell, is found based on L1 or L3 measurements reported by the UE. "SCG LTM to an incorrect PSCell" can also be named "LTM PSCell handover to an incorrect PSCell," "LTM for SCG to an incorrect PSCell," or others.

[0336] In the above definition, "successful LTM PSCell handover" means that the UE successfully completes the access procedure to the target PSCell.

[0337] In some embodiments of this disclosure, the failure type definition of the LTM PSCell handover procedure or the SCG LTM procedure may be defined as follows (e.g., in the case of selecting an appropriate PSCell after a connection failure occurs in an SCG LTM within an SN that does not involve the MN or in an SN-initiated LTM PSCell handover within an SN):

[0338] (1) If the appropriate PSCell is not one of at least one LTM candidate PSCells provided by the CU of the SN (e.g., if the appropriate PSCell is not one of at least one LTM candidate PSCells provided by the CU of the SN to the source DU or target DU or at least one candidate target DU of the SN), then it is an incorrect LTM candidate PSCell list selection at the SN or the CU of the SN, and the SN may be the source SN or the target SN or the candidate target SN.

[0339] (2) If the suitable PSCell is one of at least one LTM candidate PSCells provided by the CU of the SN (e.g., if the suitable PSCell is not one of at least one LTM candidate PSCells provided by the CU of the SN to the source DU or target DU or at least one candidate target DU of the SN), but is not one of at least one LTM candidate PSCells selected by the source DU or target DU or at least one candidate target DU of the SN, then it is an incorrect LTM candidate PSCell selection at the source DU or target DU or at least one candidate target DU of the SN.

[0340] (3) If the appropriate PSCell is one of at least one LTM candidate PSCells selected by the source DU or target DU of the SN or at least one candidate target DU, then it is an incorrect target PSCell at the source DU of the SN for the LTM PSCell handover decision (e.g., the reference ID of the target PSCell, i.e., the “target configuration ID” contained in the LTM PSCell handover command or LTM command MAC CE is incorrect).

[0341] Furthermore, if a subsequent SCG LTM or subsequent LTM PSCell handover procedure is executed, one of the functions of the MRO is to detect ping-pong occurring during the subsequent SCG LTM or subsequent LTM PSCell handover procedure. Ping-pong can be named a "ping-pong event" or "ping-pong situation," etc. The event of "ping-pong in a subsequent SCG LTM / LTM PSCell handover procedure" can be defined as follows:

[0342] - The UE successfully performs an LTM PSCell handover from the first PSCell to the second PSCell, but within a predefined finite time, the UE hands back to the first PSCell, or the UE successfully performs an LTM PSCell handover from the second PSCell back to the first PSCell. This event can occur more than once after the UE receives an RRC reconfiguration message for LTM (e.g., an LTM candidate PSCell configuration containing one or more LTM candidate PSCells).

[0343] Example 2 (LTM PSCell handover related failure information)

[0344] As described in Example 1, during an SCG LTM procedure (e.g., a PSCell change triggered by an LTM PSCell handover command or MAC CE), LTM PSCell handover failure, SCG LTM execution failure, or SCG RLF may occur. For any SCF failure, in order for the network to understand why the SCG LTM procedure was not successfully executed or to help the network understand whether or how to modify SCG LTM-related configurations (e.g., optimizing the list of LTM candidate PSCells or RA resource information for early TA acquisition or SCG LTM without RACH, or CFRA resource information included in the LTM PSCell handover MAC CE), LTM-specific information or failure information related to the LTM PSCell handover procedure needs to be stored or reported by the UE to distinguish between failures in the SCG LTM procedure and failures in the L3 PSCell change procedure. For example, the UE stores or reports SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure in messages. Messages may be existing reports (e.g., SCG failure information messages or others) or newly introduced messages. SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure can be sent by the UE to the MN. The MN can then send the SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to the source SN, target SN, or candidate target SN via existing X2 / Xn messages (e.g., SCG FAILUREINFORMATION REPORT or others) or newly introduced X2 / Xn messages. For example, in the case of intra-SN SCG LTM not involving the MN, or during intra-SN LTM PSCell handover initiated by the SN, the MN's CU can send SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to the source SN's CU. Then, the source SN's CU can send the SCG LTM-related failure information to the source SN's source DU and / or the source SN's target DU and / or at least one candidate target DU via newly introduced F1 messages or existing F1 messages (e.g., Access and Mobility Indication messages or others). In the case of SCG LTM within an SN that does not involve an MN, or in the handover of LTM PSCell within an SN initiated by an SN, the source SN is the node that serves the UE during the final initialization of the SCG LTM / LTM PSCell handover procedure or the node that triggers the SCG LTM / LTM PSCell handover procedure. In this case, the source SN and the target SN are the same node, the source SN and the candidate target SN are the same node, and the target SN and the candidate target SN are the same node.

[0345] In some embodiments, the SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure stored or reported by the UE may include LTM-specific information or LTM PSCell handover-related failure information. For example, the SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure may include at least one of the following:

[0346] (1) Information about the source PSCell (e.g., cell ID, measurement results). For example, the cell ID may include a reference ID or index that maps to the source PSCell, PCI+ carrier frequency information (e.g., ARFCN), and / or CGI information (e.g., PLMN identifier, cell identifier, and tracking area code). For example, the measurement results may include L1 measurement results or L3 measurement results;

[0347] (2) Information about failed PSCells (e.g., cell ID, measurement results). For example, measurement results may include L1 or L3 measurement results;

[0348] (3) Information about the selected beam in the target PSCell (e.g., the CTI status of the target PSCell), if indicated in the LTMPSCell switching MAC CE;

[0349] (4) Information on one or more neighboring cells (e.g., cell ID of each neighboring cell, measurement results of each neighboring cell, a flag used to indicate whether the measured neighboring cell included in the L1 or L3 measurement results is an LTM candidate PSCell);

[0350] (5) Indications regarding SCG failures that occur during the SCG LTM procedure or due to LTM PSCell handover, for example, introducing new failure types or reasons for SCG failures, such as SCG LTM failure, SCG LTM execution failure, or failure shortly after a successful SCG LTM execution; or introducing new failures to indicate that the failure occurred during the SCG LTM procedure; or introducing explicit indications regarding the type of SCG LTM cell handover; or including a new one-bit flag (adding an indicator indicating whether the last mobility performed before the SCG failure was an LTM PSCell handover procedure);

[0351] (6) A list of LTM candidate PSCells (e.g., cell IDs), for example, those not included in L1 or L3 measurement results;

[0352] (7) The reference configuration of SCG LTM, for example, is represented by IE ltm-ReferenceConfiguration-r18 configured in the RRC reconfiguration message to the UE, which contains the LTM candidate PSCell configuration of one or more LTM candidate PSCells;

[0353] (8) A list of LTM candidate PSCell configurations, each configuration being used to configure an LTM candidate PSCell, for example, represented by IE LTM-Candidate-r18 configured in the RRC reconfiguration message to the UE, an LTM candidate PSCell configuration containing one or more LTM candidate PSCells, for example, the configuration includes at least LTM-CandidateId, differential configuration located on top of the reference configuration, configuration for early UL-Sync, ltm-NoResetID, TCI status of the LTM candidate PSCell, etc.

[0354] (9) A group of one or more CSI resources configured in the LTM candidate PSCell configuration, for example, represented by the IE LTM-CSI-ResourceConfig configured in the RRC reconfiguration message to the UE, which contains one or more LTM candidate PSCell configurations.

[0355] (10) The time elapsed between the receipt of the LTM PSCell switching command or MAC CE (or the triggering of an LTM PSCell switching toward the target PSCell) and the receipt of the corresponding most recent RRC reconfiguration message of the SCG LTM;

[0356] (11) The time elapsed between the receipt of the LTM PSCell switching command or MAC CE (or the triggering of an LTM PSCell switching toward the target PSCell) and the occurrence of the SCG failure;

[0357] (12) The time elapsed between the occurrence of SCG failure and the information stored in the report or between the report itself;

[0358] (13) TA value of SCG LTM without RACH; or

[0359] (14) TA value derived from the early RACH procedure used for early TA acquisition.

[0360] In another solution, some information can be derived by the node that triggers the SCG LTM procedure or LTM PSCell handover procedure (e.g., in the case of intra-SN SCG LTM not involving MN or in intra-SN LTM PSCell handover initiated by SN, in one instance, the node is the source SN or the CU of the source SN or at least one DU of the source SN; and in another instance, the node is the MN or the CU of the MN or at least one DU of the MN; in the case of intra-SN SCG LTM involving MN or in inter-SN SCG LTM, in one instance, the node is the source SN or the CU of the source SN or at least one DU of the source SN; in another instance, the CU is a node, is the target SN or the CU of the target SN or at least one DU of the target SN; in another instance, the node is the MN or the CU of the MN or at least one DU of the MN; and in another instance, the node is the candidate target SN or the CU of the candidate target SN or at least one DU of the candidate target SN), even if the UE does not report them to the network. For example, in the case of SCG LTM within an SN that does not involve MN, or in an SN-initiated LTM PSCell handover within an SN, the source SN, its CU, or at least one of its DUs can automatically derive at least one of the following SCGLTM-related failure information or failure information related to the LTM PSCell handover procedure:

[0361] (1) Information regarding whether the measured neighboring cells included in the L1 or L3 measurement results reported by the UE are LTM candidate PSCells;

[0362] (2) Information regarding whether the failure occurred during the SCG LTM or LTM PSCell switching procedure or was due to an LTM-related SCG failure;

[0363] (3) A list of LTM candidate PSCells (e.g., cell IDs);

[0364] (4) TA values ​​used for SCG LTM without RACH or derived in the early RACH procedure for early TA acquisition;

[0365] (5) The reference configuration of LTM, for example, is represented by IE ltm-ReferenceConfiguration-r18 configured in the RRC reconfiguration message to the UE, which contains the LTM candidate PSCell configuration of one or more LTM candidate PSCells.

[0366] (6) A list of LTM candidate PSCell configurations, each configuration being used to configure an LTM candidate PSCell, for example, represented by IE LTM-Candidate-r18 configured in the RRC reconfiguration message to the UE, an LTM candidate PSCell configuration containing one or more LTM candidate PSCells, for example, the configuration includes at least LTM-CandidateId, differential configuration located on top of the reference configuration, configuration for early UL-Sync, ltm-NoResetID, TCI status of the LTM candidate PSCell, etc.

[0367] (7) A group of one or more CSI resources configured in the LTM candidate PSCell configuration, for example, represented by the IE LTM-CSI-ResourceConfig configured in the RRC reconfiguration message to the UE, which contains one or more LTM candidate PSCell configurations.

[0368] (8) The time elapsed between the receipt of an LTM PSCell switch command or MAC CE (or the triggering of an LTM PSCell switch toward the target PCell) and the receipt of the corresponding most recent RRC reconfiguration message for the SCG LTM. For example, the CU can derive this duration, which is equal to the time between the receipt of the UL RRC MESSAGE TRANSFER message (containing RRC reconfiguration completion) and the receipt of the most recent LTM CELL CHANGE NOTIFICATION message; or

[0369] (9) The time elapsed between the receipt of the LTM PSCell switching command or MAC CE (or the triggering of an LTM PSCell switching toward the target PCell) and the failure of the SCG.

[0370] In an SCG LTM or LTM PSCell handover procedure (e.g., a PSCell change triggered by an LTM PSCell handover command or MAC CE), when an SCG RLF occurs before receiving an LTM PSCell handover MAC CE, or when an LTM PSCell handover fails or an SCG LTM execution fails (i.e., the supervisory timer T304 expires), or when an SCG failure occurs shortly after a successful LTM PSCell handover from the source PSCell to the target PSCell, the receiving node (e.g., the MN or CU of the MN that receives SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure from the UE) sends the SCG LTM-related failure information to the node that triggered the LTM PSCell handover at its location (e.g., the source SN or CU of the source SN in the case of an SCG LTM within the SN that does not involve the MN, or in an LTM PSCell handover within the SN that is initiated by the SN). The CU of the source SN may send SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to the source DU and / or the target DU and / or at least one candidate target DU of the source SN via newly introduced F1 messages or existing F1 messages (such as access and mobility indication messages or others). Optionally, the CU of the MN may send SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to the DU of the MN via newly introduced F1 messages or existing F1 messages (such as access and mobility indication messages or others).

[0371] In the above embodiments, the CU (e.g., the CU of the MN, the CU of the source SN, the CU of the target SN, or the CU of the candidate target SN) can send SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to its corresponding source DU and / or target DU and / or at least one candidate target DU via newly introduced F1 messages or existing F1 messages (e.g., access and mobility indication messages or others). For example, the SCG LTM-related failure information or the failure information related to the LTM PSCell handover procedure includes at least one of the following information (the following information can be reported by the UE or derived by the CU itself):

[0372] (1) Information about the source PSCell (e.g., cell ID, measurement results). For example, the cell ID may include a reference ID or index that maps to the source PSCell, PCI+ carrier frequency information (e.g., ARFCN), and / or CGI information (e.g., PLMN identifier, cell identifier, and tracking area code). For example, the measurement results may include L1 measurement results or L3 measurement results;

[0373] (2) Information about failed PSCells (e.g., cell ID, measurement results). For example, measurement results may include L1 or L3 measurement results;

[0374] (3) Information about the selected beam in the target PSCell (e.g., the CTI status of the target PSCell), if indicated in the LTMPSCell switching MAC CE;

[0375] (4) Information on one or more neighboring cells (e.g., cell ID of each neighboring cell, measurement results of each neighboring cell, a flag used to indicate whether the measured neighboring cell included in the L1 or L3 measurement results is an LTM candidate PSCell);

[0376] (5) Indications regarding SCG failures that occur during the SCG LTM procedure or due to LTM PSCell handover, for example, introducing new failure types or reasons for SCG failures, such as SCG LTM failure, SCG LTM execution failure, or failure shortly after a successful SCG LTM execution; or introducing new failures to indicate that the failure occurred during the SCG LTM procedure; or introducing explicit indications regarding the type of SCG LTM cell handover; or including a new one-bit flag (adding an indicator indicating whether the last mobility performed before the SCG failure was an LTM PSCell handover procedure);

[0377] (6) A list of LTM candidate PSCells (e.g., cell IDs), for example, those not included in L1 or L3 measurement results;

[0378] (7) The reference configuration of LTM, for example, is represented by IE ltm-ReferenceConfiguration-r18 configured in the RRC reconfiguration message to the UE, which contains the LTM candidate PSCell configuration of one or more LTM candidate PSCells.

[0379] (8) A list of LTM candidate PSCell configurations, each configuration being used to configure an LTM candidate PSCell, for example, represented by IE LTM-Candidate-r18 configured in the RRC reconfiguration message to the UE, an LTM candidate PSCell configuration containing one or more LTM candidate PSCells, for example, the configuration includes at least LTM-CandidateId, differential configuration located on top of the reference configuration, configuration for early UL-Sync, ltm-NoResetID, TCI status of the LTM candidate PSCell, etc.

[0380] (9) A group of one or more CSI resources configured in the LTM candidate PSCell configuration, for example, represented by the IE LTM-CSI-ResourceConfig configured in the RRC reconfiguration message to the UE, which contains one or more LTM candidate PSCell configurations.

[0381] (10) The time elapsed between the receipt of the LTM PSCell switching command or MAC CE (or the triggering of an LTM PSCell switching toward the target PCell) and the receipt of the corresponding most recent RRC reconfiguration message of the SCG LTM;

[0382] (11) The time elapsed between the receipt of the LTM PSCell switching command or MAC CE (or the triggering of an LTM PSCell switching toward the target PCell) and the occurrence of the SCG failure.

[0383] (12) The time elapsed between the occurrence of the SCG failure and the report of the stored information or report;

[0384] (13) TA value of SCG LTM without RACH; or

[0385] (14) TA value derived from the early RACH procedure used for early TA acquisition.

[0386] Example 3 (MRO detection or analysis)

[0387] Example 3 provides a solution for how a network performs MRO detection or analysis on an SCG LTM or LTM PSCell switching procedure.

[0388] Example 3-1 (Mechanism for failure detection or analysis)

[0389] In the case of SCG LTM within SN without involving MN, or in the SN-initiated LTM PSCell switching procedure within SN, there are two possible solutions, namely, Solution #1 and Solution #2.

[0390] Solution #1: A delayed SCG LTM, an early SCG LTM, or an SCG LTM to an incorrect PSCell can be detected by the CU of the MN or MN. The CU of the MN or MN can, for example, indicate the failure type of the delayed SCG LTM, early SCG LTM, or SCG LTM to an incorrect PSCell to the CU of the source SN via an existing X2 / Xn message (e.g., SCG FAILURE INFORMATION REPORT or others) or a newly introduced X2 / Xn message. Then, the CU of the source SN can indicate the failure type of the delayed SCG LTM, early SCG LTM, or SCG LTM to an incorrect PSCell to the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., Access and Mobility Indication message or others).

[0391] - Optionally, the source SN or its CU may further verify whether it is the failure type or problem detected by the MN or its CU. If yes, then the source SN or its CU may respond to the MN or its CU as follows: the failure type or problem detected by the MN or its CU is correct. If no, then the source SN or its CU may respond to the MN or its CU as follows: the failure type or problem detected by the MN or its CU is incorrect; optionally, the source SN or its CU may transmit its verified failure type or problem to the MN or its CU.

[0392] - Optionally, the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may further verify whether it is the indicated detected failure type or problem. If so, then the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may respond to the CU of the source SN as follows: the indicated failure type or problem is correct. Then, the source SN or the CU of the source SN may respond to the CU of the MN or the CU of the MN as follows: the failure type or problem detected by the CU of the MN or the CU of the MN is correct. If not, then the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may respond to the CU of the source SN as follows: the failure type or problem detected by the CU of the MN or the CU of the MN is incorrect; optionally, the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may transmit its verified failure type or problem to the CU of the source SN. Next, the source SN or the CU of the source SN may respond to the MN or the CU of the MN as follows: the problem detected by the CU of the MN or the CU of the MN is an error; optionally, the source SN or the CU of the source SN may transmit the received verified failure type or problem to the CU of the MN or the CU of the MN.

[0393] Solution #2: Too late SCG LTM, too early SCG LTM, or SCG LTM to the wrong PSCell can be detected by the source SN or its CU. The source SN's CU can indicate the failure type of the too late SCG LTM, too early SCG LTM, or SCG LTM to the source DU and / or the target DU and / or at least one candidate target DU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., Access and Mobility Indication message or others).

[0394] - Optionally, the relevant DU (e.g., a source DU of the source SN and / or a target DU of the source SN and / or at least one candidate target DU of the source SN) may further verify whether it is a failure type or problem detected by the CU of the source SN. If yes, then the relevant DU may respond to the CU of the source SN as follows: the failure type / problem detected by the CU of the source SN is correct. If no, then the relevant DU may respond to the CU of the source SN as follows: the failure type or problem detected by the CU of the source SN is incorrect; optionally, the relevant DU may transmit its verified failure type or problem to the CU of the source SN.

[0395] - Optionally, the source SN or the CU of the source SN may indicate the failure type to the MN or the CU of the MN via existing X2 / Xn messages (such as SCG FAILURE TRANSFER or others) or newly introduced X2 / Xn messages.

[0396] Example 3-2 (Detection of Ping-Pong Incidents)

[0397] Similarly, statistics regarding ping-pong occurrences in subsequent SCG LTM or LTM PSCell handover procedures can be collected by the node. For example, the node that triggers the SCG LTM / LTM PSCell handover or generates the RRC reconfiguration message for the SCG LTM / LTM PSCell handover, for instance, in the case of intra-SN SCG LTM not involving MN or in intra-SN LTM PSCell handover initiated by SN, the node is the source SN or the CU of the source SN or the CU of MN or the CU of MN. Then, the ping-pong in subsequent SCG LTM / LTM PSCell handover procedures can be analyzed by the source SN or the CU of the source SN or the CU of MN or the CU of MN. In different embodiments, the following three options may exist: Option #A, Option #B, and Option #C.

[0398] Option #A: Ping-pong in subsequent SCG LTM / LTM PSCell handover procedures can be analyzed based on UE history information stored by the source SN or the CU of the source SN or the MN or the CU of the MN, or based on UE history information received from the UE or from the CU of the MN or the CU of the MN.

[0399] - For example, based on the duration of the UE's stay in the first PSCell or the second PSCell or when it returns to the first PSCell, if the UE leaves the first PSCell and then returns to the first PSCell within a predefined finite time, or if the UE stays in the second PSCell within a short predefined time, then the source SN or the CU of the source SN or the MN or the CU of the MN detects it as a ping-pong situation.

[0400] Option #B: Ping-pong in subsequent SCG LTM / LTM PSCell handover procedures can be analyzed based on the received LTM CELLCHANGE NOTIFICATION messages, for example, based on the duration between two LTM CELL CHANGE NOTIFICATION messages received from the same cell (e.g., the UE returns to its first PSCell).

[0401] - For example, the received LTM CELL CHANGE NOTIFICATION message indicates that an LTM CELL handover MAC CE is initiated to the UE. Based on the duration between receiving the LTM CELL CHANGE NOTIFICATION message from the first PSCell and receiving the LTM CELL CHANGE NOTIFICATION message from the second PSCell, and / or based on the duration between receiving the LTM CELL CHANGE NOTIFICATION message from the second PSCell and receiving the LTM CELL CHANGE NOTIFICATION message returning to the first PSCell, if the UE hands back to the first PSCell within a predefined finite time, or if the UE stays in the second PSCell for a short predefined time and leaves the second PSCell and then returns to the first PSCell (for example, the duration the UE stays in the second PSCell is equal to the time between receiving the ACCESSSUCCESS message from the second PSCell and receiving the LTM CELL CHANGE NOTIFICATION message returning to the first PSCell), then the source SN or the CU of the source SN or the MN or the CU of the MN detects it as a ping-pong situation.

[0402] Option #C: Ping-pong in subsequent SCG LTM / LTM PSCell handover procedures can be analyzed based on the received ACCESSSUCCESS messages, for example, based on the duration between two ACCESSSUCCESS messages received from the same cell (e.g., the UE returns to its first PSCell).

[0403] - For example, the received ACCESS SUCCESS message indicates the success of LTM execution containing the target PSCell ID. Based on the duration between receiving the ACCESS SUCCESS message for the first PSCell and receiving the ACCESS SUCCESS message for the second PSCell, and / or based on the duration between receiving the ACCESS SUCCESS message for the second PSCell and receiving the ACCESS SUCCESS message returning to the first PSCell, if the UE successfully switches back to the first PSCell within a predefined finite time, or if the UE remains in the second PSCell for a short predefined time and leaves the second PSCell and then successfully returns to the first PSCell, then the source SN or the CU of the source SN or the MN or the CU of the MN detects it as a ping-pong situation.

[0404] Next, the CU of the source SN or the CU of the MN can indicate the occurrence of a potential ping-pong situation to the corresponding DU (e.g., the source DU or the target DU or at least one candidate target DU other than the target DU, such as the DU where ping-pong occurs, such as the DU of the source SN, including the DU that manages the first PSCell or the DU that manages the second PSCell).

[0405] Example 3-3 (F1 Interface Signaling)

[0406] Based on Example 3-1, in the case of intra-SN SCG LTM without involving the MN, or during intra-SN LTMPSCell handover initiated by the SN, when the SCG RLF occurs before receiving the LTM PSCell handover MAC CE, or when the LTM PSCell handover fails or the SCG LTM execution fails (i.e., the supervisory timer T304 expires), or when the SCG failure occurs shortly after a successful LTM PSCell handover from the source PSCell to the target PSCell, the MN or the CU of the MN can receive SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure from the UE. Then, the MN or the CU of the MN can send appropriate PSCell information (if present) and / or SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to the node (e.g., the source SN or the CU of the source SN) where the LTM PSCell handover was triggered (e.g., the source SN or the CU of the source SN) via existing X2 / Xn messages (e.g., SCG FAILURE INFORMATION REPORT or others) or newly introduced X2 / Xn messages. There are two possible solutions: Solution #A and Solution #B.

[0407] Solution #A: The failure analysis of the source SN or the CU of the source SN to execute is as follows:

[0408] In Solution #A, if a suitable PSCell (e.g., the suitable PSCell mentioned in Example 1) is not included in at least one LTM candidate PSCell provided by the source SN or its CU to the target DU or at least one candidate target DU of the source SN, then it is inappropriate for the source SN or its CU to detect at least one LTM candidate PSCell provided by the source SN or its CU. The source SN or its CU may then modify the list of at least one LTM candidate PSCell or candidate PSCells for LTM PSCell switching. Optionally, the source SN or its CU may indicate the detected problem to the MN or its CU via an existing X2 / Xn message (e.g., SCG FAILURETRANSFER or others) or a newly introduced X2 / Xn message.

[0409] In solution #A, a suitable PSCell is included in at least one LTM candidate PSCell provided by the source SN or by the CU of the source SN to the target DU or candidate target DU of the source SN, but not in at least one LTM candidate PSCell selected or prepared by the target DU or (candidate) target DU of the source SN (i.e., the candidate target DU of the source SN is any one of at least one candidate target DU of the source SN). In different embodiments, the following two options may exist: Option #M and Option #N.

[0410] Option #M: If the CU of the source SN detects that it is an incorrect LTM candidate PSCell selection or preparation at the target DU or candidate target DU of the source SN, the CU of the source SN may indicate to the target DU or candidate target DU of the source SN, via a newly introduced F1 message or an existing F1 message (such as an Access and Mobility Indication message or others), that the incorrect LTM candidate PSCell should be selected or prepared by the target DU or candidate target DU of the source SN. For example, an explicit or implicit indication regarding the selection or preparation of the incorrect LTM candidate PSCell may be included in a newly introduced F1 message or an existing F1 message.

[0411] In option #M, optionally, the CU of the source SN may forward information about the appropriate PSCell (e.g., the cell ID of the appropriate PSCell, PCI+ carrier frequency information (e.g., ARFCN) and / or CGI information (e.g., PLMN identifier, cell identifier and tracking area code)) and / or SCGLTM-related failure information (e.g., failure information related to the LTM PSCell handover procedure as mentioned in Example 2, such as at least one LTM candidate PSCell provided by the source SN or the CU of the source SN) to the target DU or candidate target DU of the source SN, for example, via a newly introduced F1 message or an existing F1 message (e.g., access and mobility indication message or others).

[0412] In option #M, optionally, the target DU or candidate target DU of the source SN can further verify whether the problem detected by the CU of the source SN is correct or whether it is an erroneous LTM candidate PSCell selected or prepared by the target DU or candidate target DU of the source SN:

[0413] 1) If so, the target DU or candidate target DU of the source SN may modify one or more LTM candidate PSCells it has selected or prepared. Optionally, the target DU or candidate target DU of the source SN may respond to the CU of the source SN, for example, via a newly introduced F1 message or an existing F1 message (e.g., GNB-DU CONFIGURATION UPDATE message or others), that the problem detected by the CU of the source SN is correct or that the target DU or candidate target DU of the source SN has selected or prepared an incorrect LTM candidate PSCell. For example, an explicit or implicit indication regarding whether the detected problem is correct or whether the target DU or candidate target DU of the source SN has selected or prepared an incorrect LTM candidate PSCell may be included in a newly introduced F1 message or an existing F1 message.

[0414] 2) If not, then optionally, the target DU or candidate target DU of the source SN may respond to the CU of the source SN, for example via a newly introduced F1 message or an existing F1 message (e.g., a GNB-DU CONFIGURATION UPDATE message or others), as follows: the CU of the source SN has performed an error detection, i.e., it is not an incorrect LTM candidate PSCell selection or preparation in the target DU or candidate target DU of the source SN. For example, an explicit or implicit indication that the CU of the source SN has performed an error detection or that it is not an incorrect LTM candidate PSCell selection or preparation in the target DU or candidate target DU of the source SN may be included in the newly introduced F1 message or an existing F1 message. Furthermore, the target DU or candidate target DU of the source SN may notify the CU of the source SN of a detected / verified problem, such as that the LTM candidate PSCell selection or preparation is appropriate in the target DU or candidate target DU of the source SN.

[0415] In option #M, optionally, the source SN or the CU of the source SN can indicate a verified or detected problem to the MN or the CU of the MN via existing X2 / Xn messages (such as SCG FAILURETRANSFER or others) or newly introduced X2 / Xn messages.

[0416] Option #N: The CU of the source SN may, for example, forward the information of the appropriate PSCell and / or SCG LTM-related failure information (e.g., failure information related to the LTM PSCell handover procedure as mentioned in Embodiment 2, such as at least one LTM candidate PSCell provided by the source SN or its CU) to the target DU or candidate target DU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., access and mobility indication message or others). The target DU or candidate target DU of the source SN detects that one or more erroneous LTM candidate PSCells have been selected or prepared at the target DU or candidate target DU of the source SN (e.g., based on the information of the appropriate PSCell, at least one LTM candidate PSCell provided by the CU of the source SN to the target DU or (candidate) target DU of the source SN, and at least one LTM candidate PSCell selected or prepared by the target DU or (candidate) target DU of the source SN). Then, the target DU or (candidate) target DU of the source SN may modify the one or more LTM candidate PSCells it has selected or prepared;

[0417] In option #N, optionally, the target DU or (candidate) target DU of the source SN may, for example, instruct the CU of the source SN to select or prepare an error LTM candidate PSCell by the target DU or (candidate) target DU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., a GNB-DU CONFIGURATION UPDATE message or others). For example, an explicit or implicit instruction regarding the selection or preparation of an error LTM candidate PSCell may be included in a newly introduced F1 message or an existing F1 message.

[0418] In option #N, optionally, the source SN or the CU of the source SN may indicate a verified or detected problem to the MN or the CU of the MN via existing X2 / Xn messages (such as SCG FAILURETRANSFER or others) or newly introduced X2 / Xn messages.

[0419] In solution #A, if a suitable PSCell is contained in at least one LTM candidate PSCell selected or prepared by the target DU or a candidate target DU of the source SN (i.e., a candidate target DU of the source SN is any one of at least one candidate target DU of the source SN), then in different embodiments, the following two options may exist, namely, option #X and option #Y.

[0420] Option #X: The CU of the source SN detects an incorrect LTM target cell selection or decision at the source DU of the source SN (e.g., the reference ID of the target PSCell, i.e., the "target configuration ID" contained in the LTM PSCell handover command or MAC CE is incorrect).

[0421] In option #X, the CU of the source SN can instruct the source DU of the source SN to configure / indicate an incorrect LTM target PSCell via a newly introduced F1 message or an existing F1 message (such as an Access and Mobility Indication message or others). For example, an explicit or implicit indication regarding the selection or determination of an incorrect LTM target PSCell at the source DU of the source SN can be included in a newly introduced F1 message or an existing F1 message.

[0422] In option #X, optionally, the CU of the source SN may forward the appropriate PSCell information and / or SCG LTM-related failure information (e.g., failure information related to the LTM PSCell handover procedure as mentioned in Example 2, such as at least one LTM candidate PSCell provided by the source SN or the CU of the source SN, at least one LTM candidate PSCell selected or prepared by the target DU or candidate target DU of the source SN, etc.) to the source DU of the source SN, for example via newly introduced F1 messages or existing F1 messages (e.g., access and mobility indication messages or others)

[0423] In option #X, optionally, the source DU of the source SN can further verify whether the problem detected by the CU of the source SN is correct or whether it is an error at the source DU of the source SN in LTM target cell selection or decision:

[0424] (1) If so, the source DU of the source SN can modify the target PSCell for LTM PSCell switching. Optionally, the source DU of the source SN responds to the CU of the source SN, for example via a newly introduced F1 message or an existing F1 message (e.g., GNB-DU CONFIGURATION UPDATE message or others), as follows: the problem detected by the CU of the source SN is correct or the source DU of the source SN has selected or determined an incorrect LTM target PSCell. For example, an explicit or implicit indication regarding whether the detected problem is correct or the source DU of the source SN has selected or determined an incorrect LTM target PSCell may be included in a newly introduced F1 message or an existing F1 message.

[0425] (2) If not, optionally, the source DU of the source SN may respond to the CU of the source SN, for example via a newly introduced F1 message or an existing F1 message (e.g., a GNB-DU CONFIGURATION UPDATE message or others), that the CU of the source SN has performed an error detection, i.e., that at the source DU of the source SN, it is not an incorrect LTM target PSCell selection or decision. For example, an explicit or implicit indication that the CU of the source SN has performed an error detection or that it is not an incorrect LTM target PSCell selection or decision at the source DU of the source SN may be included in the newly introduced F1 message or an existing F1 message. Furthermore, the source DU of the source SN may notify the CU of the source SN of a detected / verified problem, such as that at the source DU of the source SN, the LTM target PSCell selection or decision is appropriate.

[0426] In option #X, optionally, the source SN or the CU of the source SN may indicate a verified or detected problem to the MN or the CU of the MN via existing X2 / Xn messages (such as SCG FAILURETRANSFER or others) or newly introduced X2 / Xn messages.

[0427] Option #Y: The CU of the source SN may, for example, forward the appropriate PSCell information and / or SCG LTM-related failure information (e.g., failure information related to the LTM PSCell handover procedure as mentioned in Embodiment 2, such as at least one LTM candidate PSCell provided by the source SN or its CU to the candidate target DU of the source SN, at least one LTM candidate PSCell selected or prepared by the candidate target DU of the source SN, etc.) to the source DU of the source SN. The source DU of the source SN detects that it is an incorrect LTM target PSCell selection or decision at the source SN (e.g., the reference ID of the target PSCell, i.e., the "target configuration ID" contained in the LTM PSCell handover command or MAC CE is incorrect) (e.g., based on the information of the appropriate PSCell and at least one LTM candidate PSCell selected or prepared by the (candidate) target DU of the source SN). Then, the source DU of the source SN may modify the target PSCell for the LTM PSCell handover.

[0428] In option #Y, optionally, the source DU of the source SN may, for example, indicate to the CU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., GNB-DU CONFIGURATION UPDATE message or others) that the source DU of the source SN has selected or determined the erroneous LTM target PSCell. For example, an explicit or implicit indication regarding the selection or determination of the erroneous LTM target PSCell may be included in a newly introduced F1 message or an existing F1 message. Optionally, the source SN or the CU of the source SN may indicate to the MN or the CU of the MN via an existing X2 / Xn message (e.g., SCG FAILURE TRANSFER) or a newly introduced X2 / Xn message that a detected problem (e.g., the source SN or the source DU of the source SN has selected or determined the erroneous LTM target PSCell) has been detected.

[0429] Solution #B: The CU of MN or MN can perform failure analysis, such as detecting whether it is an inappropriate LTM candidate PSCell selection at the source SN or the CU of the source SN, or whether it is an incorrect LTM candidate PSCell selection or preparation at the target DU or candidate target DU of the source SN, or whether it is an incorrect LTM target PSCell selection or decision at the source DU of the source SN. Then, the CU of MN or MN can indicate the detected problem to the source SN or the CU of the source SN, for example, via existing X2 / Xn messages (e.g., SCG FAILURE INFORMATION REPORT or others) or newly introduced X2 / Xn messages.

[0430] In Solution #B, optionally, the source SN or its CU can further verify whether the problem is detected by the MN or its CU. If so, the source SN or its CU can respond to the MN or its CU as follows: The problem detected by the MN or its CU is correct. If not, the source SN or its CU can respond to the MN or its CU as follows: The problem detected by the MN or its CU is incorrect. Optionally, the source SN or its CU can transmit the detected / verified failure type / problem to the MN or its CU. The source SN's CU can then indicate the detected failure type or problem (indicated by the MN's CU or detected or verified by the source SN's CU through its verification) to the source DU and / or the target DU and / or at least one candidate target DU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., an Access and Mobility Indication message or others).

[0431] In Solution #B, optionally, the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may further verify whether it is the indicated detected failure type or problem (indicated by the CU of the MN or detected or verified by the CU of the source SN through its verification). If yes, then the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may respond to the CU of the source SN as follows: the indicated detected failure type or problem is correct. Optionally, the source SN or the CU of the source SN may respond to the CU of the MN or the CU of the MN as follows: the indicated detected failure type or problem is correct. If no, then the source DU of the source SN and / or the target DU of the source SN and / or at least one candidate target DU of the source SN may respond to the CU of the source SN as follows: the indicated detected failure type or problem is incorrect. Optionally, the source SN or the CU of the source SN may respond to the CU of the MN or the CU of the MN as follows: the problem detected by the CU of the MN or the CU of the MN is incorrect.

[0432] Example 3-4 (UE Context Identifier)

[0433] When a source DU, target DU, or candidate target DU of a source SN receives SCG LTM-related failure information or LTM PSCell handover procedure-related failure information from a CU of the source SN (e.g., in the case of SN-internal SCGLTM involving or not involving MN, the source SN is the node serving the UE or triggering the SCGLTM / LTM PSCell handover procedure at the last initialization of the SCG LTM / LTM PSCell handover procedure), the UE context (e.g., UE-related information, such as UE-related configurations or mobility policies of interest) can be released. Examples 3 and 4 provide solutions on how to enable a source DU, target DU, or candidate target DU of a source SN to retrieve the UE context.

[0434] To identify the UE context in the source DU, target DU, or candidate target DU of the source SN when receiving SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure from the CU of the source SN (e.g., in the case of SCG LTM within an SN involving or not involving the MN, the source SN is the node that serves the UE or triggers the SCG LTM / LTM PSCell handover procedure at the last initialization of the handover procedure), the following operations may exist:

[0435] (1) The source DU of the source SN may create a reference related to the UE context or a configuration or set of parameters used by a UE or group of UEs involved in the LTM procedure (e.g., via the source DU implementation of the source SN, the reference may be referred to as "configuration information" or "mobility information" or "LTM information" or other names), and the source DU of the source SN may send this reference to the CU of the source SN, for example, via a UE context modification response message or a UL RRC message transmission message or an LTM cell change notification message or other messages (which may be referred to as "configuration information" or "mobility information" or "LTM information" or other names).

[0436] (2) The target DU or candidate target DU of the source SN may create a reference related to the UE context or a configuration or set of parameters used by a UE or group of UEs involved in the LTM procedure (e.g., via the target DU or candidate target DU implementation of the source SN, the reference may be referred to as "configuration information" or "mobility information" or "LTM information" or other names). The target DU or candidate target DU of the source SN may send this reference to the CU of the source SN, for example, via a UE context setting response message or a UE context modification response message or an access success message or other message (which may be represented by "configuration information" or "mobility information" or "LTM information" or other names).

[0437] (3) Specifically, if a reference (which may be represented by “configuration information”, “mobility information”, “LTM information” or other names) is received from a source DU of a source SN, then the CU of the source SN may store the reference; if a reference (which may be represented by “configuration information”, “mobility information”, “LTM information” or other names) is received from a target DU of a source SN, then the CU of the source SN may store the reference; and if a reference (which may be represented by “configuration information”, “mobility information”, “LTM information” or other names) is received from a candidate target DU of a source SN, then the CU of the source SN may store the reference.

[0438] (4) When the CU of the source SN sends SCG LTM-related failure information or failure information related to the LTM PSCell handover procedure to the source DU of the source SN, for example via a newly introduced F1 message or an existing F1 message (such as an access and mobility indication message or other messages), the CU of the source SN may send the reference received from the source DU of the source SN (which may be represented by “configuration information” or “mobility information” or “LTM information” or other names) back to the source DU of the source SN.

[0439] (5) When the CU of the source SN sends SCG LTM-related failure information or LTMPSCell handover procedure-related failure information to the target DU or candidate target DU of the source SN via a newly introduced F1 message or an existing F1 message (e.g., access and mobility indication message or other message), the CU of the source SN may send the reference received from the target DU or candidate target DU of the source SN (which may be represented by “configuration information” or “mobility information” or “LTM information” or other names) back to the target DU or candidate target DU of the source SN.

[0440] Based on a reference (which may be represented by "configuration information", "mobility information", "LTM information" or other names), the source DU of the source SN, the target DU of the source SN, or the candidate target DU of the source SN can identify the context of the UE.

[0441] Example 4 (RA Reporting Enhancement for LTM)

[0442] Example 4 provides enhancements to the RA report in the case of the MCG LTM / LTM PCell switchover procedure or the SCG LTM / LTM PSCell switchover procedure.

[0443] To avoid RACH conflicts, the PRACH configuration for the RA procedure triggered by early TA acquisition (or the RA procedure for LTM triggering or the PRACH configuration for the early RACH procedure for early TA acquisition) can be exchanged via the Xn interface (e.g., between the source CU or source node and the candidate target CU or candidate target node in the case of inter-CU LTM, or between the source CU or source node and the target CU or target node in the case of inter-CU LTM, or between the CU of the MN and the CU of the SN in the case of coexistence of MCG LTM and SCG LTM (or between the MN and the SN, where the SN can be the source SN, the target SN, or the candidate target SN), via newly introduced Xn messages or existing Xn messages (e.g., XN SETUP REQUEST, XN SETUP RESPONSE, NG-RAN NODE CONFIGURATION UPDATE, NG-RAN NODE CONFIGURATION UPDATE). ACKNOWLEDGE or other) or exchanged via the F1 interface (e.g., between CU and candidate target DU, or between CU and source DU, or between CU and target DU, via newly introduced F1 messages or existing F1 messages (e.g., F1 SETUP REQUEST, GNB-DU CONFIGURATION UPDATE, GNB-CU CONFIGURATION UPDATE messages or others), where CU, source DU, target DU, or candidate target DU can be MN, source SN, target SN, or candidate target SN).

[0444] To help the network optimize RACH-related configurations for MCG LTM or SCG LTM (e.g., optimizing RA resource information for early TA acquisition or LTM without RACH, or CFRA resource information contained in LTM cell handover commands or MAC CEs), it is necessary to enhance the RA report to include LTM-related information. For example, the RA report may include information related to early RACH procedures, LTM without RACH, or RACH-related information for early TA acquisition. The UE may store and / or report RA reports. For instance, an RA report may contain at least one of the following:

[0445] (1) New RA purpose, such as indicating that the RA is triggered by initiating an early TA acquisition for LTM or that the RA procedure is triggered in an MCG or SCG LTM procedure, or that the RA procedure is an LTM-triggered RA or an early TA acquisition-triggered RA. Alternatively, the RA report may contain an indication that the RA is triggered by initiating an early TA acquisition for MCG or SCG LTM procedure or that the RA procedure is triggered in an MCG or SCG LTM procedure;

[0446] (2) Information about the cell where the RA procedure is performed, such as the cell ID, which may include the cell’s reference ID / index (e.g., the “target configuration ID” contained in the LTM cell handover command or MAC CE) or PCI+ carrier frequency information (e.g., ARFCN) and / or CGI information (e.g., PLMN identifier, cell identifier and tracking area code).

[0447] (3) TA value of MCG or SCG LTM procedure without RACH, for example, if it is included in LTM cell handover command or MAC CE;

[0448] (4) Indication regarding whether the UE receives CFRA resource-related information, for example, in an LTM cell handover command or MAC CE;

[0449] (5) RA resource-related parameters (e.g., RA resource-related information and / or CFRA resource-related information used for early TA acquisition or MCG or SCG LTM procedures without RACH, for example, contained in the LTM cell handover command or MAC CE, for example, including at least the preamble index, UL / SUL indicator, SSB index, PRACH mask index, Msg1 repeat number, frequency start, FDM, subcarrier spacing, start preamble, or number of preambles); or

[0450] (6) Instructions regarding the success of the RACH procedure for early TA acquisition, the success of the early RACH procedure, or the success of the MCG or SCG LTM procedure without RACH, or instructions regarding the failure of the RACH procedure for early TA acquisition, the failure of the early RACH procedure, or the failure of the MCG or SCG LTM procedure without RACH. Once the preamble transmission is instructed to the lower layer, the RACH procedure toward the candidate cell can be considered successful or complete. In the case of MCG LTM, the RA report needs to be enhanced to include MCG LTM-related information, and the candidate cell is the candidate PCell; and in the case of SCG LTM, the RA report needs to be enhanced to include SCG LTM-related information, and the candidate cell is the candidate PSCell.

[0451] In the case of an MCG LTM procedure or an LTM PCell handover procedure, the CU (e.g., the node that triggers the MCG LTM procedure or LTM PCell handover procedure or the node that generates the RRC reconfiguration message for the MCG LTM procedure or LTM PCell handover procedure, such as the source node or MN or the CU of the source node or the CU of the source MN) may receive the RA report directly from the UE or from a third node that receives the RA report from the UE; and then the CU may transmit the RA report to its corresponding source DU and / or target DU and / or at least one candidate target DU, for example, via a newly introduced F1 message or an existing F1 message (e.g., access and mobility indication message or others) (e.g., if received directly from the UE or from a third node).

[0452] In the case of an SCG LTM or LTM PSCell handover procedure, the UE may transmit an RA report to the MN or its CU or SN or the CU of the SN (e.g., the SN is a source SN, target SN, candidate target SN, or the node that triggered the SCG LTM / LTM PSCell handover, or the node that generated the RRC reconfiguration message for the SCG LTM / LTM PSCell handover); and then, the MN or its CU or SN or the CU of the SN may, for example, transmit an RA report to its corresponding source DU and / or target DU and / or at least one candidate target DU via a newly introduced F1 message or an existing F1 message (e.g., an Access and Mobility Indication message or others) (e.g., if received from the UE or the MN or the SN). For example, the UE may transmit an RA report to the MN; and then, the MN may transmit an RA report to the source SN and / or the target SN. For example, the UE may transmit an RA report to the source SN and / or the target SN. To give another example, if the CU of the source SN or the CU of the target SN receives an RA report, then the CU of the source SN or the CU of the target SN may, for example, transmit an RA report to its corresponding source DU and / or target DU and / or at least one candidate target DU via a newly introduced F1 message or an existing F1 message (such as an access and mobility indication message or others).

[0453] The description herein is provided to enable those skilled in the art to make or use this disclosure. Those skilled in the art will understand that various modifications to this disclosure are possible, and that the general principles defined herein may be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An auxiliary node SN, comprising: At least one memory; and At least one processor, coupled to the at least one memory and configured to cause the SN to: In response to the occurrence of a failure associated with the L1 / L2 triggered mobility LTM PSCell handover procedure from the source primary and secondary cell group PSCell of the user equipment UE to the target PSCell, failure information related to the LTM PSCell handover procedure is obtained. The failure mentioned therein includes at least one of secondary cell group SCG LTM execution failure or SCG failure.

2. The SN of claim 1, wherein the processor is configured to perform one of the following, or wherein the SN comprises a centralized unit CU and the CU is configured to perform one of the following: Receive information about the failure type from the master node MN, wherein the failure type is detected by the MN; or Detect the failure type of the failure.

3. The SN of claim 2, wherein the SN further comprises at least one distributed unit (DU), the CU being configured to transmit at least one of the following to the at least one DU: The failure information related to the LTM PSCell switching procedure; The information received from the MN regarding the failure type; or The information regarding the failure type detected by the CU.

4. The SN according to claim 3, wherein the at least one DU is configured to: Detect the failure type of the failure; or Verify the failure type detected by the MN or the CU.

5. The SN according to claim 4, wherein the at least one DU is configured to: The failure type detected by the at least one DU is transmitted to the CU; or If the failure type detected by the MN or the CU is correct, then transmit a message to the CU indicating that the failure type detected by the MN or the CU is correct; or If the failure type detected by the MN or the CU is incorrect, then a message indicating that the failure type detected by the MN or the CU is incorrect is transmitted to the CU.

6. The SN according to any one of claims 2 to 5, wherein the failure type comprises at least one of the following: The first type of failure is defined as too late SCG LTM, wherein the UE has received the configuration information of the LTM PSCell handover procedure, but the SCG failure occurs after the UE has stayed in the source PSCell for a certain period of time or before the LTM PSCell handover command that triggers the LTM PSCell handover procedure to the UE, and the appropriate PSCell, which is different from the source PSCell, is found based on the layer 1 L1 or layer 3 L3 measurement results reported by the UE. The second type of failure is defined as premature SCG LTM, wherein the SCG failure occurs shortly after the successful completion of the LTM PSCell handover from the source PSCell to the target PSCell or the SCG LTM execution failure occurs, and the source PSCell is the appropriate PSCell based on the L1 or L3 measurement results reported by the UE. or The third failure type is defined as an SCG LTM to an incorrect PSCell, wherein the SCG failure occurs shortly after the successful completion of the LTM PSCell handover from the source PSCell to the target PSCell or the SCGLTM execution fails, and the appropriate PSCell, which is different from the source PSCell and the target PSCell, is found based on the L1 or L3 measurement results reported by the UE.

7. The SN of claim 2, wherein the processor is configured such that the SN or the CU is configured to: In response to the occurrence of the failure, receive information about the appropriate PSCell or select the appropriate PSCell.

8. The SN according to any one of claims 2 to 5 and 7, wherein the failure type further comprises at least one of the following: The fourth failure type, wherein the appropriate PSCell selected in response to the occurrence of the failure is not one of the first set of LTM candidate PSCells provided by the CU of the SN to at least one DU of the SN; The fifth failure type, wherein the suitable PSCell is one of the first group of LTM candidate PSCells, but not one of the second group of LTM candidate PSCells selected by the at least one DU; or The sixth failure type, wherein the suitable PSCell is one of the second group of LTM candidate PSCells.

9. The SN of claim 8, wherein the processor is configured such that the SN or the CU is configured to detect whether the failure type is one of the fourth failure type, the fifth failure type, and the sixth failure type.

10. The SN of claim 9, wherein if the failure type is the fourth failure type, then the processor is configured such that the SN or the CU is configured to determine that the first set of LTM candidate PSCells provided by the SN or the CU is inappropriate.

11. The SN of claim 9, wherein the SN further comprises at least one distributed unit (DU), and if the failure type is the fifth failure type, then the DU is configured to: The detection is performed by selecting one or more erroneous LTM candidate PSCells by at least one DU; or A third message is transmitted to the at least one DU, instructing the at least one DU to select one or more erroneous LTM candidate PSCells.

12. The SN of claim 9, wherein if the failure type is the sixth failure type, then the CU is configured to: Detection of source DU selection error LTM target PSCell by the SN; or The source DU transmits fourth information indicating that the source DU selects the erroneous LTM target PSCell.

13. The SN of claim 8, wherein the SN further comprises at least one distributed unit (DU); wherein the DU is configured to transmit at least one of the failure information or the information of the appropriate PSCell to the at least one DU; and wherein the at least one DU is configured to detect the failure type.

14. The SN of claim 13, wherein if the failure type is the fifth failure type, then the at least one DU is configured to: The detection is performed by selecting one or more erroneous LTM candidate PSCells by at least one DU; or The CU is sent a sixth message instructing the at least one DU to select one or more erroneous LTM candidate PSCells.

15. The SN of claim 13, wherein if the failure type is the sixth failure type, then the source DU is configured to: Detecting the incorrect LTM target PSCell selected by the source DU; or The seventh message is transmitted to the CU, indicating that the source DU selects the erroneous LTM target PSCell.

16. The SN of claim 1, wherein the SN includes a centralized unit CU for obtaining the failure information, the processor being configured such that the SN or the CU is configured to automatically derive the failure information or receive the failure information stored or transmitted by the UE, wherein the failure information includes at least one of the following: Information regarding the source PSCell; Information about the PSCell where the failure occurred; Information regarding the selected beam in the target PSCell; Information about one or more adjacent cells; The L1 or L3 measurement results of the source PSCell; The failure occurred at the location of the L1 or L3 measurement result of the PSCell; The L1 or L3 measurement results of the adjacent cells; Information indicating whether the neighboring cells included in the L1 or L3 measurement results are LTM candidate PSCells; Information indicating that the failure occurred during the LTM PSCell switching procedure; Information regarding at least one LTM candidate PSCell configured for the LTM PSCell switching procedure; Cell configuration information of at least one LTM candidate PSCell; The LTM PSCell handover procedure includes a set of Channel State Information (CSI) resources. Reference configuration for the LTM PSCell switching procedure; The time elapsed between the receipt of the LTM PSCell handover command and the receipt of the most recent RRC reconfiguration message of the LTM PSCell handover procedure; The time elapsed between the receipt of the LTM PSCell switching command and the occurrence of the failure; The time elapsed between the occurrence of the failure and the transmission of the failure information by the UE; Time alignment TA value of SCG LTM without random access channel RACH; or TA values ​​exported from the early RACH procedure used for early TA acquisition.

17. The SN of claim 1, wherein the SN comprises a centralized unit (CU) and at least one distributed unit (DU), wherein the processor is configured to enable the SN or the CU to detect whether a ping-pong event has occurred, and wherein, for the ping-pong event, after a successful LTM PSCell handover from the first PSCell to the second PSCell, the UE switches back to the first PSCell within a predefined time period or the UE successfully performs another LTM PSCell handover from the second PSCell back to the first PSCell.

18. A master node MN, comprising: At least one memory; and At least one processor coupled to the at least one memory and configured to cause the MN to: In response to the occurrence of a failure associated with the L1 / L2 triggered mobility LTM PSCell handover procedure from the source primary / secondary cell group PSCell of the UE to the target PSCell, perform at least one of the following: Receive failure information related to the LTM PSCell handover procedure from the UE; or Obtain information about the failure type. The failure mentioned therein includes at least one of secondary cell group SCG LTM execution failure or SCG failure.

19. A master node MN, comprising: At least one memory; and At least one processor coupled to the at least one memory and configured to cause the MN to: Transmit to or receive from the auxiliary node SN the physical random access channel (PRACH) configuration information for the random access RA procedure triggered by early timing advance TA acquisition.

20. A user equipment (UE) comprising: At least one memory; and At least one processor coupled to the at least one memory and configured to cause the UE to: In response to the occurrence of a failure associated with an L1 / L2 triggered mobility LTM PSCell handover procedure from the source primary / secondary cell group cell PSCell to the target PSCell of the UE, failure information related to the LTM PSCell handover procedure is stored, wherein the failure includes at least one of secondary cell group SCG LTM execution failure or SCG failure; and The failure message was transmitted.

Images