Apparatus and method for controlling uplink path in dual connectivity

Abstract

An apparatus including a first node operating in a master node (MN) in dual connectivity is provided. The apparatus can include at least one transceiver and at least one processor coupled to the at least one transceiver. The at least one processor is capable of receiving an SN modification request message from a second node operating in a secondary node (SN) over an Xn interface. The SN modification request message can include indication information for the MN terminating split bearer. The indication information can indicate availability of UL usage at the SN. The at least one processor can identify an uplink (UL) primary path of the MN terminated split bearer based on indication information for the MN terminated split bearer, and can transmit information for indicating the UL primary path to the terminal.

Description

Technical Field

[0001] The present disclosure generally relates to dual connectivity, for example, to an apparatus and / or method for controlling an uplink path in dual connectivity. Background Art

[0002] Dual connectivity refers to a technology in which a user equipment (e.g., a mobile phone) is directly or indirectly connected to two or more independent heterogeneous and / or homogeneous wireless communication cell groups with separate radio resource control entities at the same time. It is possible to improve the efficiency of frequency usage by using frequency resources located in different frequency bands. Summary of the invention

[0003] Certain example embodiments may provide an apparatus and / or method for a dual-connected master node (MN) to provide a secondary node (SN) with an indication of use of an uplink (UL) path in the MN.

[0004] Certain example embodiments may provide an apparatus and / or method for a secondary node (SN) for dual connectivity to provide a primary node (MN) with an indication of usage of an uplink (UL) path in the SN.

[0005] According to certain example embodiments, a method performed by a first node operating as a master node (MN) in a dual connection may include receiving an SN modification request message from a second node operating as a secondary node (SN) via an Xn interface. The SN modification request message may include indication information for a MN-terminated split bearer. The indication information may indicate the availability of uplink (UL) usage at the SN. The method may include identifying a UL primary path of the MN-terminated split bearer based on the indication information for the MN-terminated split bearer. The method may include sending information indicating the UL primary path to a user equipment (UE). The UL primary path may be associated with a primary cell group (MCG) of the MN and one of a secondary cell group (SCG) of the SN.

[0006] According to certain example embodiments, a method performed by a second node operating as a secondary node (SN) in a dual connection may include obtaining uplink state information through a measurement report or a medium access control (MAC) indication from a user equipment (UE). The method may include generating indication information for a MN terminated split bearer based on the uplink state information. The indication information may indicate the availability of uplink (UL) use at the SN. The method may include sending an SN modification request message to a first node operating as a primary node (MN) via an Xn interface. The indication information for the MN terminated split bearer may be used to identify the UL primary path of the MN terminated split bearer. The UL primary path may be associated with one of the primary cell group (MCG) of the MN and the secondary cell group (SCG) of the SN.

[0007] According to certain example embodiments, a device of a first node operating as a master node (MN) in a dual connection may include at least one transceiver and at least one processor directly or indirectly coupled to the at least one transceiver. The at least one processor may be configured to receive an SN modification requirement message from a second node operating as a secondary node (SN) via an Xn interface. The SN modification requirement message may include indication information for MN termination split bearer. The indication information may indicate the availability of uplink (UL) usage at the SN. The at least one processor may be configured to identify the UL primary path of the MN termination split bearer based on the indication information for the MN termination split bearer. The at least one processor may be configured to send information indicating the UL primary path to a user equipment (UE). The UL primary path may be associated with one of the primary cell group (MCG) of the MN and the secondary cell group (SCG) of the SN.

[0008] According to certain example embodiments, a device of a second node working as a secondary node (SN) in a dual connection may include at least one transceiver and at least one processor directly or indirectly coupled to the at least one transceiver. The at least one processor may be configured to obtain uplink state information through a measurement report or a medium access control (MAC) indication from a user equipment (UE). The at least one processor may be configured to generate indication information for MN termination split bearer based on the uplink state information. The indication information may indicate the availability of uplink (UL) use at the SN. The at least one processor may be configured to send an SN modification request message to a first node working as a primary node (MN) via an Xn interface. The indication information for the MN termination split bearer may be used to identify the UL primary path of the MN termination split bearer. The UL primary path may be associated with one of the primary cell group (MCG) of the MN and the secondary cell group (SCG) of the SN.

[0009] Effects of the Invention

[0010] An apparatus and / or method according to example embodiments may make it possible to improve the performance of uplink transmission by enabling measurement of uplink quality outside a range managed by each node.

[0011] Effects that can be obtained are not limited to those described above, and any other effects not mentioned herein will be clearly understood by a person of ordinary skill in the technical field to which the present disclosure belongs from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1a and Figure 1b Each shows an example of a wireless communication environment according to an example embodiment.

[0013] Figure 2 An example of a downlink path and an uplink path in dual connectivity (DC) according to an example embodiment is shown.

[0014] Figure 3a An interface of a base station with a distributed deployment according to an example embodiment is shown.

[0015] Figure 3b An example of signaling with distributed deployed base stations according to an example embodiment is shown.

[0016] Figure 4a An interface in a dual connection according to an example embodiment is shown.

[0017] Figure 4b Various layers of a control plane in dual connectivity according to an example embodiment are shown.

[0018] Figure 4c The layers of the user plane in dual connectivity according to an example embodiment are shown.

[0019] Figure 5 An example of a radio bearer according to an example embodiment is shown.

[0020] Figure 6a An example of signaling for uplink (UL) path control of a secondary node (SN) terminating a split bearer according to an example embodiment is shown.

[0021] Figure 6b Another example of signaling for UL path control of an SN terminated split bearer according to an example embodiment is shown.

[0022] Figure 7a An example of signaling for UL path control of a master node (MN) terminating a split bearer according to an example embodiment is shown.

[0023] Figure 7b Another example of signaling for UL path control of a MN terminated split bearer according to an example embodiment is shown.

[0024] Figure 8a An example of signaling between CU-DUs for controlling the UL path of an SN terminated split bearer according to an example embodiment is shown.

[0025] Figure 8b An example of signaling between CU-DUs for controlling a MN-terminated UL path of a split bearer according to an example embodiment is shown.

[0026] Fig. 9 An example of messages for UL path control of a SN terminated split bearer according to an example embodiment is shown.

[0027] Fig.10 An example of messages for UL path control of a MN-terminated split bearer according to an example embodiment is shown.

[0028] Fig.11 A functional configuration of a device serving as an MN or a SN according to an exemplary embodiment is shown. DETAILED DESCRIPTION

[0029] The terms used in the present disclosure are only used to better describe a certain embodiment and may not be intended to limit the scope of other embodiments. Unless the context clearly stipulates otherwise, singular expressions may include plural expressions. The terms used herein (including technical terms and scientific terms) may have the same meanings as those commonly understood by those skilled in the art to which the present disclosure relates. The terms defined in general dictionaries among the terms used in the present disclosure may be interpreted as having the same or similar meanings as those terms in the context of the relevant technology, and unless explicitly defined in the present disclosure, they will not be interpreted in an ideal or overly formal sense. In some cases, even the terms defined in the present disclosure may not be interpreted as excluding example embodiments.

[0030] In various examples of the present disclosure described below, a hardware method will be described as an example. However, since various example embodiments include techniques utilizing both hardware-based methods and software-based methods, they are not intended to exclude software-based methods.

[0031] As used in the following description, terms referring to signals (e.g., signal, information, message, signaling), terms referring to resources (e.g., symbol, time slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), opportunity), terms referring to the state of resources (enabled, disabled, activated, deactivated, available, unavailable, convenient, applicable, accessible), terms used to indicate operation states (e.g., steps, operations, processes), terms referring to data (e.g., packets, user streams, information, bits, symbols, codewords), terms referring to channels, terms referring to network entities, terms referring to components of devices, etc. are shown for the convenience of description. Therefore, the present disclosure is not limited to those terms described below, and other terms with equivalent technical meanings may be used for this purpose.

[0032] In addition, throughout this disclosure, expressions such as, for example, "higher than" or "lower than" may be used to determine whether a particular condition is satisfied or fulfilled, but this is merely a description for expressing an example and is not intended to exclude the meaning of "greater than or equal to" or "less than or equal to". A condition described as "greater than or equal to" may be replaced with "higher than", a condition described as "less than or equal to" may be replaced with "lower than", and conditions described as "greater than or equal to" and "lower than" may be replaced with "higher than" and "less than or equal to", respectively. In addition, unless explicitly stated otherwise, "A" to "B" is intended to mean at least one of the elements from A (including A) and B (including B).

[0033] In addition, the present disclosure uses terms used in some communication specifications (e.g., 3GPP (3rd Generation Partnership Project), xRAN (Extensible Radio Access Network), and O-RAN (Open Radio Access Network) to describe various embodiments, but this is merely an example for description. Various embodiments of the present disclosure can be easily modified and applied even in other communication systems.

[0034] Throughout the present disclosure, a measurement signal may refer to a signal measured by a terminal in order to obtain signal quality for use in mobility, admission control, or radio resource management (RRM). For example, the measurement signal may be at least one of a synchronization signal (e.g., SS block), a beam reference signal (BRS), a beam refinement reference signal (BRRS), a cell-specific reference signal (CRS), a channel state information-reference signal (CSI-RS), or a demodulation reference signal (DM-RS). According to an embodiment, the base station may transmit not only one type of measurement signal, but also each type of measurement signal of two or more types.

[0035] Signal quality may refer to, for example, at least one of reference signal received power (RSRP), beam reference signal received power (BRSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), signal to interference and noise ratio (SINR), carrier to interference and noise ratio (CINR), signal to noise ratio (SNR), error vector magnitude (EVM), bit error rate (BER), or block error rate (BLER). In addition to the above examples, it should be clearly understood that other terms with equivalent technical meanings or other metrics indicating channel quality may also be used. In the following, the term "high signal quality" used in the present disclosure may refer to occasions where the signal quality value related to the signal size is relatively large or the signal quality value related to the error rate is relatively small. A higher signal quality value may imply that a smoother wireless communication environment is guaranteed. In addition, the best beam may refer to a beam with the highest signal quality among multiple beams.

[0036] Certain example embodiments relate to a process for determining an uplink primary path in a dual connection of a wireless communication system. More specifically, the present disclosure provides a solution for providing information about the use of an uplink (UL) path by a master node (MN) to a secondary node (SN) or by a SN to a MN in order to determine the UL primary path in a split bearer. In addition, by sharing information about the use of the UL path between the MN and the SN, the present disclosure makes it possible to significantly improve the performance of data transmission via an optimal uplink primary path.

[0037] Figure 1a and Figure 1b An example of a wireless communication environment according to an embodiment is shown. Figure 1a and Figure 1b A terminal (or user equipment) and a base station are each shown as a node using a wireless channel in a wireless communication system.

[0038] Reference Figure 1a and Figure 1b , the wireless communication system may include a first base station 110, a second base station 120 and a terminal 130.

[0039] The first base station 110 or the second base station 120 is a network infrastructure that provides wireless access. In addition to the term "base station", the first base station 110 or the second base station 120 may also be referred to as an "access point (AP)", "eNodeB (or eNB)", "fifth generation node (5G node)", "5G NodeB (NB)", "next generation Node B (gNB)", "radio access network (RAN) node", transmission / reception point (TRP), distributed unit (DU), radio unit (RU), remote radio head (RRH), or other terms with technical meanings equivalent thereto. According to an embodiment, the first base station 110 or the second base station 120 may be directly or indirectly connected to one or more transmission / reception points (TRPs). The first base station 110 or the second base station 120 may send a downlink signal to the terminal 130 or receive an uplink signal from the terminal 130 through one or more TRPs.

[0040] The terminal 130, which is a device used by a user, can communicate with the first base station 110 or the second base station 120 through a wireless channel. In some cases, the terminal 130 can work without any user intervention. That is, at least one of the terminals 130 can be a device that performs machine type communication (MTC), and the user can not carry the device. In addition to the terminal, the terminal 130 can also be referred to as "user equipment (UE)", "mobile station", "subscriber station", "customer premises equipment (CPE)", "remote terminal", "wireless terminal", "electronic device" or "vehicle terminal", "user equipment", or any other term equivalent to it in technical meaning.

[0041] The terminal 130 according to the embodiment can be configured in dual connectivity (DC) using both the first base station 110 and the second base station 120. Dual connectivity refers to a technology in which a terminal can be directly or indirectly connected to two different radio resource entities to use radio resources allocated by each radio resource entity. In MR-DC, a UE (e.g., UE 130, which can be, for example, a mobile phone) in an RRC connected state (e.g., RRC_CONNCETED) can be configured to use radio resources provided by two independent schedulers, each of which can be located at a NG-RAN node (e.g., a first base station 110 and a second base station 120). Here, one node is a master node (MN) and the other node is a secondary node (SN). The MN and the SN can be connected via a network interface, and the MN can be connected to a core network. The SN may or may not be directly or indirectly connected to the core network.

[0042] MN may provide a master cell group (MCG). MN may be referred to as an M-NODE or M-NG-RAN node other than MN. MCG may include one or more cells. MCG may include a master cell (PCell). MCG may include multiple aggregated cells. MCG may include PCell and one or more secondary cells (SCell). SN may provide a secondary cell group (SCG). SN may be referred to as an S-NODE or S-NG-RAN node other than SN. SCG may include one or more cells. SCG may include multiple aggregated cells. Like MCG, SCG may include PCell and / or SCell. A cell that is a PCell in SCG may be referred to as a primary secondary cell (PSCell). A subcell group may include a PSCell and one or more SCells. In the following, a special cell (SpCell) may be used as a term including PCell and PSCell. SpCell refers to a master cell of an MCG or SCG. In other words, the SpCell of an MCG may indicate a PCell, and the SpCell of an SCG may indicate an SCell.

[0043] Definitions of possible types of DC may be provided as follows.

[0044] EN-DC: Dual connectivity in which the eNB is directly or indirectly connected to the Evolved Packet Core (EPC) and the terminal is directly or indirectly connected to the eNB as the MN and the gNB as the SN. Here, the gNB may be referred to as en-gNB, and the en-gNB may or may not be connected to the EPC.

[0045] NGEN-DC: Dual connectivity in which the eNB is directly or indirectly connected to the 5G core (5GC) and the terminal is directly or indirectly connected to the eNB as the MN and the gNB as the SN. Here, the eNB can be referred to as ng-eNB.

[0046] NE-DC: Dual connectivity in which the gNB is directly or indirectly connected to the 5GC and the terminal is directly or indirectly connected to the gNB working as the MN and the eNB working as the SN. Here, the eNB may be referred to as ng-eNB.

[0047] NR-DC: Dual connectivity in which the gNB is directly or indirectly connected to the 5GC and the terminal is connected to the gNB as the MN and the gNB as the SN. NR-DC can also be used when the UE is directly or indirectly connected to a (e.g., single) gNB to perform the roles of both MN and SN and configures both MCG and SCG.

[0048] The terminal 130 may support multi-radio (MR)-DC. The terminal 130 may be directly or indirectly connected to the first base station 110 and the second base station 120. The first base station 110 may be a MN and the second base station 120 may be a SN so that they can be connected to the terminal. Together with the carrier aggregation (CA) provided by each base station, the dual connection may provide a higher data rate. The first base station 110 and the second base station 120 may send downlink traffic to the terminal 130 or receive uplink traffic from the terminal 130 as a MN and a SN, respectively.

[0049] The terminal 130 may be located within the cell coverage of the first base station 110. The terminal 130 may be located within the cell coverage of the second base station 120. In a split bearer, downlink transmission may be performed through a PCell and a PSCell. A split bearer may refer to a radio bearer having an RLC bearer in both an MCG and an SCG in an MR-DC. The terminal 130 may use the wireless network resources of the first base station 110 and the second base station 120 together through a split bearer. According to an embodiment, the split bearer may be an MN terminated bearer. An MN terminated bearer may refer to a bearer in which a packet data convergence protocol (PDCP) is in the MN. The split bearer may be an SN terminated bearer. An SN terminated bearer refers to a bearer in which a PDCP is in the SN.

[0050] The uplink transmission of the terminal 130 may be performed through at least one of the PCell or the PSCell. The terminal 130 may determine whether to transmit the uplink data to one of the first base station 110 and the second base station 120 or whether to transmit the uplink data to the first base station 110 and the second base station 120 by splitting based on the size of the uplink data. In this case, it is required to set the uplink main path used in both situations. For example, the channel state of the uplink transmission at the cell edge may be bad. For example, the terminal 130 may be located at the cell edge of the PSCell. Figure 1a Different, multiple terminals can be Figure 1b The PScell ​​connected to the terminal 130 is shown. That is, multiple terminals can access the second base station 120. In such a situation, it is required to find the UL primary path of the terminal 130.

[0051] Figure 2 An example of a downlink path and an uplink path in dual connectivity (DC) according to an embodiment is shown. The first base station 110 may serve as a MN of the dual connectivity, and the second base station 120 may serve as a SN of the dual connectivity.

[0052] Reference Figure 2 , the server 200 may send downlink traffic to the terminal 130. In a split bearer, the path of the downlink traffic may include at least two paths. For example, the split bearer may be an SN-terminated split bearer. The server 200 may provide downlink traffic to the second base station 120 via path 251. Then, path 251 may branch into two paths from the second base station 120. The first path may include a backhaul 253 and a first wireless network 255. The terminal 130 may receive downlink traffic from the second base station 120 via the first base station 110. The second path may include a second wireless network 257 (e.g., see DLTCP). The terminal 130 may receive downlink traffic directly from the second base station 120.

[0053] Transmission Control Protocol (TCP) type services may be the primary services of the network. TCP service transmission relies on feedback sent by the receiving end for end-to-end flow control. The terminal 130 may send uplink feedback (e.g., an acknowledgement (ACK) or a negative acknowledgement (NACK)) to the server 200. The current primary UL path of the terminal 130 may include an uplink wireless network 261 with the second base station 120. The terminal 130 may send uplink feedback to the second base station 120. The second base station 120 may send uplink feedback to the server 200 via path 263. In this case, as Figure 1bAs shown, the uplink channel state of the terminal 130 may be poor due to the terminal being connected to the PScell. Such a bad channel state may delay feedback. When the traffic is congested in a specific path, the server 200 may reduce the data transmission rate according to a specific TCP flow control algorithm. However, the reduced transmission rate may reduce its throughput. At the same time, when the uplink traffic can be sent to the server 200 without delay through the first base station 110, the terminal 130 can send uplink feedback without reducing throughput. In order to achieve higher throughput, the terminal 130 is required to change the main UL path to the wireless network with the first base station 110. However, as Figure 2 As shown, in the SN terminated split bearer, the second base station 120 as the SN does not know the uplink channel state of the first base station 110 as the MN. That is, the second base station 120 may not ensure that the state of the uplink channel between the terminal 130 and the first base station 110 is higher than the state of the uplink channel between the terminal 130 and the second base station 120.

[0054] In order to solve the above problems, the exemplary embodiments propose a solution for the MN to inform the SN of the uplink channel state of the MN or for the SN to inform the MN of the uplink channel state of the SN so as to accurately set the uplink primary path in the split bearer. According to the embodiment, in the SN terminating the split bearer, the MN can send information about the uplink usage of the MN to the SN. According to the embodiment, in the MN terminating the split bearer, the SN can send information about the uplink usage of the SN to the MN.

[0055] In the following, reference will be made to Figures 3a to 5 Describe the nodes, interfaces and hierarchical structure according to the distributed deployment of base stations as MN or SN. Then, refer to Figures 6a to 10 Describe the operations of MN and SN.

[0056] Figure 3a An interface of a base station with a distributed deployment according to an embodiment is shown.

[0057] Reference Figure 3a , MN may refer to an NG-RAN node that provides MCG in DC. MN may include a central unit (CU). CU may include a user plane (CU-UP) 301 and a control plane (CU-CP) 303. Hereinafter, the CU-UP 301 of the MN may be referred to as MN-UP. The CU-CP 303 of the MN may be referred to as MN-CP. MN-UP 301 and MN-CP 303 may perform communication via an E1 interface. MN may include a distributed unit (DU) 305. Hereinafter, the DU 305 of the MN may be referred to as MN-DU. MN-DU 305 and MN-CP 303 may perform communication via an F1 interface.

[0058] SN may refer to an NG-RAN node that provides SCG in DC. SN may include CU. CU may include CU-UP 311 and CU-CP 313. Hereinafter, CU-UP 311 of SN may be referred to as SN-UP. CU-CP 313 of SN may be referred to as SN-CP. SN-UP 311 and SN-CP 313 may perform communication through an E1 interface. SN may include a distributed unit (DU) 315. Hereinafter, DU 315 of SN may be referred to as SN-DU. SN-DU 315 and SN-CP 313 may perform communication through an F1 interface.

[0059] The MN and the SN may communicate via a backhaul interface (e.g., an Xn interface). The MN-CP 303 may send information to the SN-CP 313 via the Xn interface. The SN-CP 313 may send information to the MN-CP 303 via the Xn interface.

[0060] Figure 3b An example of signaling with distributed deployed base stations according to an embodiment is shown.

[0061] Reference Figure 3b , the base station may include UP 351 of the CU, CP 353 of the CU, and DU 355. First, DU 355 may send a medium access control (MAC) indication to UP 351. The MAC indication may include a downlink data delivery status (DDDS). DU355 may notify UP 351 of the UL radio link interruption / recovery cause. UP 351 may send a UL configuration to CP 353 via an E1 interface. Here, the UL configuration may include information about uplink usage. Then, CP 353 may provide RRC signaling. CP353 may send a UL configuration to DU 355 via an F1 interface. However, this scheme requires the participation of UP 351. Since more nodes are required to process information, the probability of failure increases. In addition, even if the MAC indication fails to be sent to UP 351, a mechanism for retransmitting the MAC indication is not defined, and therefore the above scheme is not suitable for determining a stable UL configuration. Therefore, instead of F1-U signaling from DU 355 to UP 351, example embodiments propose signaling between CP 353 and another CP 353 (eg, signaling using an Xn interface) or signaling between DU 355 and CP 353 (eg, F1 interface).

[0062] Figure 4a An interface in a dual connection according to an embodiment is shown.

[0063] Reference Figure 4a, network entities for dual connectivity may include UE 430, MN-CU 410, MN-DU 415, SN-CU 420, and SN-DU 425. UE 430 may support MR-DC.

[0064] UE 430 may be connected to a first NG-RAN node. The first NG-RAN node may include MN-CU 410 and MN-DU 415. UE 430 may communicate with MN-DU 415 through a Uu interface. MN-DU 415 may communicate with MN-CU 410 through an F1 interface. MN-CU 410 and MN-DU 415 may provide an MCG. UE 430 may be connected to a second NG-RAN node. The second NG-RAN node may include SN-CU 420 and SN-DU 425. UE 430 may communicate with SN-DU 425 through a Uu interface. SN-DU 425 may communicate with SN-CU 420 through an F1 interface. SN-CU 420 and SN-DU 425 may provide an SCG.

[0065] Figure 4b Various layers of a control plane in dual connectivity according to an embodiment are shown. Figure 4c 2 shows the layers of the user plane in the dual connection according to the embodiment. Figure 4a As described in , the network entities for dual connectivity may include UE 430, MN-CU 410, MN-DU 415, SN-CU 420 and SN-DU 425.

[0066] Reference Figure 4b In the control plane, the CU may host the radio resource control (RRC) protocol and the packet data convergence protocol (PDCP) protocol, and the DU may host the radio link control (RLC) layer, the medium access control (MAC) layer, and the physical (PHY) layer. The F1 interface between the CU and the DU may be referred to as F1-C (control).

[0067] Reference Figure 4c In the control plane, the CU may host the SDAP protocol and the PDCP protocol, and the DU may host the RLC layer, the MAC layer, and the PHY layer. The F1 interface between the CU and the DU may be referred to as F1-U (user).

[0068] Figure 5 An example 500 of a radio bearer according to an embodiment is shown. The radio bearer may include a signaling radio bearer (SRB) and a data radio bearer (DRB). The SRB may be used as a path for sending RRC messages in the control plane. The DRB may be used as a path for sending user data in the user plane. Figure 5In the present invention, bearers constituting the user plane of NR-NR DC are described as an example, but the example embodiments may also be applied to various types of DCs such as, for example, EN-DC, NE-DC, and NGEN-DC.

[0069] Reference Figure 5 , MN can be a gNB. MN can provide MCG. SN can be a gNB. SN can provide SCG. MN and SN can communicate via Xn interface. In the user plane, MN can receive one or more quality of service (QoS) flows through SDAP protocol. MN can perform QoS flow mapping with data radio bearer (DRB). MN can map at least one QoS flow to DRB. In the user plane, SN can receive one or more QoS flows through SDAP protocol. SN can perform QoS flow mapping with DRB. SN can map at least one QoS flow to DRB.

[0070] From the UE perspective, DRBs may be of three types. These three types may include MCG bearers, SCG bearers, and split bearers. MCG bearers may refer to radio bearers in which RLC bearers exist only in MN (or MCG). SCG bearers may refer to radio bearers in which RLC bearers exist only in SN (or SCG). Split bearers may refer to radio bearers in which RLC bearers exist in both MN (or MCG) and SN (or SCG).

[0071] From the network perspective, DRBs may be of two types. These two types may include MN-terminated bearers and SN-terminated bearers. MN-terminated bearers may refer to bearers where PDCP is in the MN. SN-terminated bearers may refer to bearers where PDCP is in the SN.

[0072] The process according to the example embodiment is used to control the UL path of the terminal of the DC. In the MCG bearer or the SCG bearer, the UL path of the terminal is not required for selection. This is because the terminal of the MCG bearer can send UL services to the MN. Similarly, the terminal of the SCG bearer can send UL services to the SN. The process according to certain example embodiments is to select whether the target of the UL path for delivering UL services is for the MN or the SN. Therefore, the wireless bearer that is the target of the UL path according to the embodiment can be a split bearer.

[0073] Split bearers can provide a high degree of freedom for downlink transmission and uplink transmission. For split bearers, the gNB can independently configure downlink transmission and uplink transmission. For example, in a split bearer, the terminal can receive DL services through both the MN radio spectrum and the SN radio spectrum and can send UL services only in any one of the MN and the SN. As another example, in a split bearer, the terminal can receive DL services through both the MN radio spectrum and the SN radio spectrum, send split UL services to any one of the MN and the SN, and send another split UL service to the other of the MN and the SN. The threshold set for the terminal (for example, ul-DataSplitThreshold of 3GPP TS 38.331) can be used to determine whether to split. The uplink path used in all the above examples may be referred to as the uplink main path. As referred to Figure 2 As described above, since uplink feedback affects the throughput of flow control, it is required to identify the best uplink primary path.

[0074] According to an embodiment, the base station may configure an uplink main path for the terminal. According to an embodiment, the base station may send an RRC reconfiguration message (e.g., RRCReconfiguration of 3GPP TS 38.331) to the terminal. The RRC reconfiguration message may include a radio bearer configuration (e.g., RadioBearerConfig IE (Information Element) of 3GPP TS 38.331). The radio bearer configuration may be used for adding, modifying or releasing SRBs, MRBs (multicast / broadcast service (MBS) radio bearers) and / or DRBs. In particular, the radio bearer configuration may include parameters related to PDCP. The radio bearer configuration may or may not include parameters related to SDAP.

[0075] Parameters related to PDCP may be included in a PDCP configuration (e.g., PDCP-Config of 3GPP TS 38.331). When the currently configured radio bearer is a split bearer, two or more RLC entities in the terminal may be associated with one PDCP entity. The two or more RLC entities may include a primary RLC entity and one or more child RLC entities. For UL data transmission, the PDCP configuration may include information indicating that two or more RLC entities are associated with one PDCP entity (e.g., "moreThanOneRLC" IE of 3GPP TS 38.331). According to an embodiment, the PDCP configuration may include information about the primary path (e.g., "primarypath" IE of 3GPP TS 38.331). The information about the primary path may indicate a cell group ID and a logical channel identifier (LCID) of the primary RLC entity.

[0076] According to an embodiment, the PDCP configuration may include information about a split threshold (e.g., ul-DataSplitThreshold of TS 38.331 of 3GPP). The terminal may identify the split threshold from the PDCP configuration. The split threshold may indicate the data size. For example, the split threshold may indicate 100 bytes. As another example, the split threshold may indicate 200 bytes. When the terminal sends uplink data whose size is greater than the split threshold, the terminal may divide the uplink data. According to another embodiment of the present disclosure, when a split bearer is configured, the PDCP configuration may not include information about the split threshold. The default value of the threshold may be infinity. That is, the terminal may not perform the division of the uplink data.

[0077] Generally speaking, the UL path requires selection of a cell group with relatively good channel quality (e.g., RSRP, RSRQ, SINR) to avoid failure in delivery of UL packets. In addition to channel quality, the base station as MN or the base station as SN may also identify the UL primary path based on various parameters such as, for example, the number of terminals using the cell group, the available resources of the cell group, and the congestion status of the cell group.

[0078] In the MN-terminated split bearer, the PDCP is located in the base station acting as the MN. Figure 5 As shown, the split bearer includes paths from the PDCP branch to two RLC entities. Therefore, such a change in the UL main path can be performed by the MN. This is because the UL main path is related to the PDCP configuration. At the same time, the base station as the MN can obtain uplink measurement results for cells related to the base station (for example, at least one serving cell or at least one neighboring cell) from the terminal. However, the base station as the MN may not be able to obtain uplink measurement results for cells related to the base station as the SN. In the absence of usage information about the uplink of the base station as the SN, the base station as the MN may have difficulty in identifying the best UL main path for the MN to terminate the split bearer.

[0079] Similar to the MN terminated split bearer, in the SN terminated split bearer, the PDCP is located in the base station acting as the SN. Such a change in the UL primary path can be performed by the SN. At the same time, the base station acting as the SN can obtain uplink measurement results for cells related to the base station (e.g., at least one serving cell or at least one neighboring cell) from the terminal. However, the base station acting as the SN cannot obtain uplink measurement results for cells related to the base station acting as the MN. Therefore, without usage information about the uplink of the base station acting as the MN, it may be difficult for the base station acting as the SN to identify the best UL primary path for the SN terminated split bearer.

[0080] As a solution to the above, a solution may be considered to configure the terminal with configuration information for the cell related to the SN when the MN configures the measurement cell. However, there may be the following limitation: the value of the parameter configured by the MN for the terminal should be the same as the value of the parameter configured by the SN for the terminal, so the determination of the MN and the determination of the SN are most likely to be different from each other. In addition, since a certain measurement gap is required to be set, this may result in reduced throughput. Alternatively, another solution may be considered to perform periodic measurements in the MN and the SN respectively and share these measurement results. However, such periodic measurements may impose a certain burden on the power of the terminal.

[0081] Certain example embodiments may solve the above-mentioned problems via signaling of the MN and the SN. Figure 3a The interface can be used to set the best UL path for the split bearer.

[0082] According to an embodiment, the base station as the MN may send information about the uplink usage of the MN to the base station as the SN by using an Xn interface message of the current standard specification. The base station as the SN may identify the primary path for the SN to terminate the split bearer based on the information about the uplink usage of the MN. Figure 6a and Figure 6b , an embodiment in which information about uplink usage of a MN is sent to a base station acting as a SN is described for SN terminated split bearer.

[0083] According to an embodiment, the base station as the SN may send information about the uplink usage of the SN to the base station as the MN by using an Xn interface message of the current standard specification. The base station as the MN may identify the primary path for the MN to terminate the split bearer based on the information about the uplink usage of the SN. Figure 7a and Figure 7b , an embodiment in which information about uplink usage of a MN is sent to a base station acting as a SN is described for SN terminated split bearer.

[0084] Figure 6a An example of signaling for controlling a secondary node (SN) to terminate an uplink (UL) path of a split bearer according to an embodiment is shown. MN-CP 610, MN-UP 615, SN-CP 620, SN-UP 625, or UE 630 is shown as a node for UL path control. For each node, refer to Figures 2 to 5 The description of the interfaces between the described nodes may also be applied to the MN-CP 610, the MN-UP 615, the SN-CP 620, the SN-UP 625 and / or the UE 630.

[0085] Reference Figure 6aIn operation S601, the MN-CP 610 may receive a measurement report or a medium access control (MAC) instruction. The measurement report may include at least one of a measurement result for a serving cell of the MN or a measurement result for a neighboring cell. The measurement result may indicate a radio state of an uplink channel of the MN. The MAC indication may include a downlink data delivery state (DDDS). The purpose of delivering the DDDS is to provide feedback from a corresponding node to a node hosting an NR PDCP entity so that the node hosting the NR PDCP entity can control downlink user data flow through the corresponding node for each data radio bearer. According to an embodiment, the MN-CP 610 may determine whether a UL path using the MCG is available based on at least one of the measurement report or the MAC indication.

[0086] In operation S603, the MN-CP 610 may send an SN modification request message to the SN-CP 620 through the Xn interface. According to an embodiment, the SN modification request message may include indication information. The indication information may include information about the use of the UL path. Throughout the present disclosure, the indication information may indicate whether MCG resources or SCG resources can be used for the UL path in the split bearer, that is, its availability. The PDCP of the SN-terminated split bearer is located in the SN, and the RLC and MAC of the SN-terminated split bearer are located in both the MN and the SN. In order to determine the best UL primary path, the SN-CP 620 may require information about uplink radio channels in the MN other than the SN. The MN-CP 610 may determine whether the UL path using the MCG is available. As the determination of the MN-CP 610 is provided to the SN, the SN is able to more accurately identify the best UL primary path.

[0087] According to an embodiment, the SN modification request message may include PDU session resource modification information. The PDU session resource information may be configured for the SN terminated split bearer. For example, the PDU session resource modification information may be the "PDUSession Resource Modification Info-SN terminated" IE of 3GPP TS 38.423. The IE may include information related to the PDU session resource for a request to modify a DRB configured with an option corresponding to the SN terminated bearer. The request may be initiated by the M-NG-RAN node.

[0088] According to an embodiment, the PDU session resource information may include a DRB and indication information corresponding to the DRB. The indication information may indicate whether the MCG resource can be used as a UL path in the DRB. For example, the PDU session resource information may include parameters as shown in the following table.

[0089] [Table 1]

[0090]

[0091]

[0092] Here, the term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The type of the DRB may be an SN terminated split bearer. "UL Path Usage Indication" may indicate indication information. The term "ULPath Usage Indication" may indicate the availability of UL usage associated with the MCG resources of the MN in the SN terminated split bearer. According to an embodiment, the indication information may only indicate whether the UL usage associated with the MCG resources is available. According to another embodiment, the indication information may indicate any one of the specified values. The specified value may indicate "unavailable", "shared" or "only". The term "unavailable" may indicate that the MCG is not available for UL data. The indication information may indicate "shared". The term "shared" may indicate that the MCG and other MCGs are available for UL data together. The indication information may indicate "only". "Only" may indicate that the MCG is available for UL data. According to another embodiment, the indication information may include whether the UL associated with the MCG resources is available and a metric (e.g., channel quality) related to the current uplink state when the UL is available. In operation S605, the SN-CP 620 may determine that the UL path is to be changed. The SN-CP 620 may identify the current UL primary path. The current UL primary path may refer to the UL primary path configured for the SN-terminated split bearer in the UE 130. The SN-CP 620 may identify the best UL primary path. When the current UL primary path is different from the best UL primary path, the SN-CP 620 may determine that the UL path is to be changed. According to an embodiment, the SN-CP 620 may identify the best UL primary path based on the indication information. The indication information may indicate the availability of an uplink wireless network provided by the MN. The UL primary path may be a first path using MCG resources or a second path using SCG resources. The first path may refer to an uplink wireless network provided by the MN. The second path may refer to an uplink wireless network provided by the SN. The availability may be determined by the MN-CP 610. For example, the indication information may indicate that the uplink wireless network provided by the MN is available for the SN-terminated split bearer. As another example, the indication information may indicate that the uplink wireless network provided by the MN is not available for the SN-terminated split bearer.

[0093] The SN-CP 620 may identify the best UL primary path based on the indication information and the uplink state information of the SN. The uplink state information of the SN may be collected through the wireless network of the SN. For example, the uplink state information of the SN may include a measurement report received from a terminal (e.g., UE 630) connected to the SN. For example, the SN-CP 620 may indicate that the channel quality of the uplink wireless network provided by the SN is lower than a threshold, and the indication information may indicate that the uplink wireless network provided by the MN is available. The SN-CP 620 may identify the uplink wireless network provided by the MN as the best UL primary path. As another example, the SN-CP 620 may indicate that the channel quality of the uplink wireless network provided by the SN is higher than a threshold, and the indication information may indicate that the uplink wireless network provided by the MN is unavailable. The SN-CP 620 may identify the uplink wireless network provided by the SN as the best UL primary path. As another example, the SN-CP 620 may indicate that the channel quality of the uplink wireless network provided by the SN is higher than a threshold, and the indication information may indicate that the uplink wireless network provided by the MN with the indication information is available. The SN-CP 620 may identify the currently configured primary path as the best UL primary path. It may not be advantageous in terms of radio resource management to unnecessarily change the currently configured UL primary path when all is possible.

[0094] In operation S607, the SN-CP 620 may send a bearer context modification request message to the SN-UP 625 via the E1 interface. The bearer context modification request message may include the UL configuration of the SCG in the split bearer (e.g., the UL configuration IE of 3GPP TS38.463). This is because the UL main path has changed. The UL configuration may indicate whether the SCG can be used for UL services. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the SCG is not used for UL data. The UL configuration may indicate "shared". The term "shared" may indicate that the SCG is used for UL data together with other SCGs. The UL configuration may indicate "only". The term "only" may indicate that only the SCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the indication information provided by the MN.

[0095] In operation S609, the SN-UP 625 may send a bearer context modification response message to the SN-CP 620 through the E1 interface.

[0096] In operation S611, the SN-CP 620 may send an SN Modification Request Acknowledge message to the MN-CP 610 through an Xn interface. According to an embodiment, the SN Modification Request message may include PDU session resource modification information. The PDU session resource information may be configured for the SN terminated split bearer. For example, the PDU session resource modification information may be a "PDU Session Resource Modification ResponseInfo-SN terminated" IE of 3GPP TS 38.423. The IE may include information related to the PDU session resource for a request to modify a DRB configured with an option corresponding to the SN terminated bearer.

[0097] According to an embodiment, the SN modification request confirmation message may include a UL configuration. The PDU session resource information of the SN modification request confirmation message may include a DRB and a UL configuration corresponding to the DRB. This is because the UL main path has changed. The UL configuration may indicate whether the SCG can be used for UL services. For example, the PDU session resource information may include the parameters shown in Table 2 below.

[0098] [Table 2]

[0099]

[0100] Here, the term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The type of the DRB may be an SN-terminated split bearer. The term "UL Configuration" may indicate a UL configuration. "UL Configuration" may include information about UL usage in an SN-terminated split bearer. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the SCG is not used for UL data. The UL configuration may refer to "shared". The term "shared" may indicate that the SCG and other SCGs are used together for UL data. The UL configuration may indicate "only". The term "only" may indicate that only the SCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the indication information provided by the MN. In operation S613, the MN-CP 610 may send a bearer context modification request message to the MN-UP 615 via an E1 interface. According to an embodiment, the bearer context modification request message may include a UL configuration. This is because the UL main path has changed. The UL configuration may indicate whether the MCG can be used for UL services. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the MCG is not used for UL data. The UL configuration may refer to "shared". The term "shared" may indicate that the MCG is used for UL data together with other MCGs. The UL configuration may indicate "only". The term "only" may indicate that only the MCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the UL configuration provided by the SN (i.e., the UL configuration received from operation S611).

[0101] In operation S615, the MN-UP 615 may send a bearer context modification response message to the MN-CP 610 through the E1 interface.

[0102] In operation S617, the MN-CP 610 may send an RRC reconfiguration message to the UE 630. The RRC reconfiguration message may be configured to carry the SN RRC reconfiguration. This is because the settings related to the SN have changed. The RRC reconfiguration message may include a PDCP configuration. The PDCP configuration may include information for indicating a UL primary path. For UL data transmission, the PDCP configuration may include information indicating that two or more RLC entities are associated with one PDCP entity (e.g., "moreThanOneRLC" IE of 3GPP TS 38.331). According to an embodiment, the PDCP configuration may include information about the primary path (e.g., "primarypath" IE of 3GPP TS 38.331).

[0103] In operation S619, the UE 630 may send an RRC reconfiguration complete message to the MN-CP 610. The RRC reconfiguration complete message may be configured to carry the SN RRC reconfiguration complete message.

[0104] In operation S621, the MN-CP 610 may send an SN reconfiguration complete message to the SN-CP 620 through an Xn interface. The SN reconfiguration complete message may be configured to carry an SN RRC reconfiguration complete message.

[0105] exist Figure 6a In the embodiment of determining the UL primary path based on the indication information of the MN in the SN termination split bearer, it has been described. According to another embodiment, the indication information can be used to determine the values ​​of other parameters of the PDCP configuration and the UL primary path. According to an embodiment, the split threshold (e.g., ul-DataSplitThreshold of 3GPP TS 38.331) of the PDCP configuration can be determined based on the indication information.

[0106] exist Figure 6a , operations for configuring the UL main path of the SN termination bearer in a structure in which the base station is divided into DU, CU-UP, and CU-CP are described. However, the example embodiments may also be applied to a structure in which the base station is divided into only DU and CU (e.g., a structure in which CU-CP and CU-UP are not separated), or may be applied to a structure in which the base station is not separated. In such occasions, some operations may be omitted. For example, in a structure in which CU-CP and CU-UP are not separated, operation S607, operation S609, operation S613, and / or operation S615 may be omitted.

[0107] Figure 6b Another example of signaling for controlling the UL path of a SN-terminated split bearer according to an embodiment is shown. Figure 6a In response to the SN-CP 620 receiving the indication information, it has been identified that the UL primary path has changed. However, the operation of changing the optimal primary path of the SN-CP 620 may be performed after the SN modification request process is performed. In this case, the SN-CP 620 is required to change the UL configuration. MN-CP 610, MN-UP 615, SN-CP 620, SN-UP 625, or UE 630 is shown as a node for path control. For each node and the above reference Figures 2 to 5 The description of the interfaces between the described nodes may be applied to the MN-CP 610 , the MN-UP 615 , the SN-CP 620 , the SN-UP 625 , or the UE 630 .

[0108] Reference Figure 6bIn operation S651, the MN-CP 610 may receive a measurement report or a medium access control (MAC) instruction. Operation S651 may correspond to Figure 6a Operation S601. Figure 6a The description of operation S601 in FIG. 1 may be applied to operation S651 in the same or similar manner.

[0109] In operation S653, the MN-CP 610 may send an SN modification request message to the SN-CP 620 through the Xn interface. Operation S653 may correspond to Figure 6a Operation S603. Figure 6a The description of operation S603 in may be applied to operation S653 in the same or similar manner.

[0110] In operation S655, the SN-CP 620 may send an SN Modification Request Acknowledge message to the MN-CP 610 through the Xn interface. The SN-CP 620 may send an SN Modification Request Acknowledge message to the MN-CP 610 in response to the SN Modification Request message. Figure 6a Different, since this is before the UL primary path is changed, the SN modification request confirmation message may not include the UL configuration.

[0111] In operation S657, the SN-CP 620 may determine that the UL path is to be changed. The SN-CP 620 may identify the current UL primary path. The current UL primary path may refer to the UL primary path configured for the SN-terminated split bearer in the UE 630. The SN-CP 620 may identify the best UL primary path. When the current UL primary path is different from the best UL primary path, the SN-CP 620 may determine that the UL path is to be changed. According to an embodiment, the SN-CP 620 may identify the best UL primary path based on the indication information. The indication information may indicate the availability of an uplink wireless network provided by the MN. The UL primary path may be a first path using MCG resources or a second path using SCG resources. The first path may refer to an uplink wireless network provided by the MN. The second path may refer to an uplink wireless network provided by the SN. The availability may be determined by the MN-CP 610. For example, the indication information may indicate that the uplink wireless network provided by the MN is available for the SN-terminated split bearer. As another example, the indication information may indicate that the uplink wireless network provided by the MN is not available for the SN-terminated split bearer. Operation S657 may correspond to Figure 6a Operation S605. Figure 6a The description of operation S605 in may be applied to operation S657 in the same or similar manner.

[0112] In operation S659, the SN-CP 620 may send an SN modification required message to the MN-CP 610 through the Xn interface. According to an embodiment, the SN modification required message may include PDU session resource modification information. The PDU session resource information may be configured for the SN terminated split bearer. For example, the PDU session resource modification information may be the "PDU Session Resource Modification Required Info-SN terminated" IE of 3GPP TS 38.423. The IE may include information related to the PDU session resources for a request to modify a DRB configured with an option corresponding to the SN terminated bearer. The request may be initiated by the S-NG-RAN node. For example, the SN modification required message may be referred to as an SN modification message.

[0113] According to an embodiment, the SN modification request message may include a UL configuration. The PDU session resource information of the SN modification request message may include a DRB and a UL configuration corresponding to the DRB. This is because the UL main path has changed. The UL configuration may indicate whether the SCG can be used for UL services. For example, the PDU session resource information may include the parameters shown in Table 3 below.

[0114] [Table 3]

[0115]

[0116] Here, the term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The type of the DRB may be an SN-terminated split bearer. The term "UL Configuration" may indicate a UL configuration. The term "UL Configuration" may include information about UL usage in an SN-terminated split bearer. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the SCG is not used for UL data. The UL configuration may indicate "shared". The term "shared" may indicate that the SCG and other SCGs are used together for UL data. The UL configuration may indicate "only". The term "only" may indicate that only the SCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the indication information provided by the MN. In operation S661, the MN-CP 610 may send a bearer context modification request message to the MN-UP 615 via an E1 interface. Operation S661 may correspond to Figure 6a Operation S613. Figure 6a The description of operation S613 in may be applied to operation S661 in the same or similar manner.

[0117] In operation S663, the MN-UP 615 may send a bearer context modification response message to the MN-CP 610 through the E1 interface.

[0118] In operation S665, MN-CP 610 may send an RRC reconfiguration message to UE 630. Operation S665 may correspond to Figure 6a Operation S617 in Figure 6a The description of operation S617 in may be applied to operation S665 in the same or similar manner.

[0119] In operation S667, the UE 630 may send an RRC reconfiguration complete message to the MN-CP 610. The RRC reconfiguration complete message may be configured to carry the SN RRC reconfiguration complete message.

[0120] In operation S669, the MN-CP 610 may send an SN Modification Confirm message to the SN-CP 620 through the Xn interface. The SN Modification Confirm message may be configured to carry an SN RRC Reconfiguration Complete message.

[0121] In operation S671, the SN-CP 620 may send a bearer context modification request message to the SN-UP 625 via the E1 interface. Operation S671 may correspond to Figure 6a Operation S607. Figure 6a The description of operation S607 may be applied to operation S671 in the same or similar manner.

[0122] In operation S673, the SN-UP 625 may send a bearer context modification response message to the SN-CP 620 through the E1 interface.

[0123] exist Figure 6b In the embodiment of determining the UL primary path based on the indication information of the MN in the SN termination split bearer, it has been described. According to another embodiment, the indication information can be used to determine the values ​​of other parameters of the PDCP configuration and the UL primary path. According to an embodiment, the split threshold (e.g., ul-DataSplitThreshold of 3GPP TS 38.331) of the PDCP configuration can be determined based on the indication information.

[0124] exist Figure 6bIn the above, operations for configuring the UL main path of the SN termination bearer in a structure in which the base station is divided into DU, CU-UP and CU-CP have been described. However, the example embodiments may also be applied to a structure in which the base station is divided into only DU and CU (e.g., a structure in which CU-CP and CU-UP are not separated) or a structure in which the base station is not separated. In such a case, some operations may be omitted. For example, in a structure in which CU-CP and CU-UP are not separated, operation S661, operation S663, operation S671 and / or operation S673 may be omitted.

[0125] Figure 7a An example of signaling for controlling a master node (MN) to terminate a UL path of a split bearer according to an embodiment is shown. MN-CP 710, MN-UP 715, SN-CP 720, SN-UP 725, or UE 730 is shown as a node for UL path control. For each node and the above reference Figures 2 to 5 The description of the interfaces between the described nodes may also be applied to the MN-CP 710 , the MN-UP 715 , the SN-CP 720 , the SN-UP 725 , or the UE 730 .

[0126] Reference Figure 7a In operation S701, the SN-CP 720 may receive a measurement report or a medium access control (MAC) instruction. The measurement report may include at least one of a measurement result for a serving cell of the SN or a measurement result for a neighboring cell. The measurement result may indicate a radio state of an uplink channel of the SN. The MAC indication may include a downlink data delivery state (DDDS). The purpose of delivering the DDDS is to provide feedback from a corresponding node to a node hosting an NR PDCP entity so that the node hosting the NR PDCP entity can control the downlink user data flow through the corresponding node for each data radio bearer. According to an embodiment, the SN-CP 720 may determine whether a UL path using an SCG is available based on at least one of a measurement report or a MAC indication.

[0127] In operation S703, the SN-CP 720 may send an SN modification request message to the MN-CP 710 through the Xn interface. According to an embodiment, the SN modification request message may include indication information. The indication information may include information about the use of the UL path. The indication information may indicate whether the MCG resources or the SCG resources are available for the UL path in the split bearer, i.e., availability. The PDCP of the MN-terminated split bearer is located in the MN, and the RLC and MAC of the MN-terminated split bearer are located in both the MN and the SN. In order to determine the best UL primary path, the MN-CP 710 requires information about the uplink radio channel in the SN other than the MN. The SN-CP 720 may determine whether the UL path using the SCG is available. As the determination of the SN-CP 720 is provided to the MN, the MN may more accurately identify the best UL primary path. For example, the SN modification request message may be referred to as an SN modification message.

[0128] According to an embodiment, the SN modification required message may include PDU session resource modification information. The PDU session resource information may be configured for the MN terminated split bearer. For example, the PDU session resource modification information may be "PDUSession Resource Modification Required Info-MN terminated" of 3GPP TS 38.423. The IE may include information related to the PDU session resource for a request to modify a DRB configured with an option corresponding to the MN terminated bearer. The request may be initiated by the S-NG-RAN node.

[0129] According to an embodiment, the PDU session resource information may include a DRB and indication information corresponding to the DRB. The indication information may indicate whether the MCG resources are available for the UL path in the DRB. For example, the PDU session resource information may include parameters as shown in Table 4 below.

[0130] [Table 4]

[0131]

[0132] Here, the term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The type of the DRB may be a MN terminated split bearer. The term "UL Path Usage Indication" may indicate the indication information. The term "UL Path Usage Indication" may indicate the availability of UL usage associated with the SCG resources of the MN in the MN terminated split bearer. According to an embodiment, the indication information may simply indicate whether the UL associated with the SCG resources is available. According to another embodiment, the indication information may indicate one of the specified values. The specified value may indicate "unavailable", "shared" and "only". The term "unavailable" may indicate that the SCG is not available for UL data (i.e., disabled, deactivated). The indication information may indicate "shared". The term "shared" may indicate that the SCG and other CGs (e.g., MCG) can be used for UL data together (i.e., enabled, activated). The indication information may indicate "only". The term "only" may indicate that the SCG can be used for UL data. According to another embodiment, the indication information may include whether the UL associated with the SCG resource is available and a metric (e.g., channel quality) associated with the current uplink state when the UL is available. In operation S705, the MN-CP 710 may determine that the UL path is to be changed. The MN-CP 710 may identify the current UL main path. The current UL main path may refer to the UL main path configured for the MN termination split bearer in the UE 730. The MN-CP 710 may identify the best UL main path. When the current UL main path is different from the best UL main path, the MN-CP 710 may determine that the UL path is to be changed. According to an embodiment, the MN-CP 710 may identify the best UL main path based on the indication information. The indication information may indicate the availability of an uplink wireless network provided by the MN. The UL main path may be a first path using MCG resources or a second path using SCG resources. The first path may refer to an uplink wireless network provided by the MN. The second path may refer to an uplink wireless network provided by the SN. The availability may be determined by the SN-CP 720. For example, the indication information may indicate that the uplink wireless network provided by the SN is available for the MN to terminate the split bearer. As another example, the indication information may indicate that the uplink wireless network provided by the SN is not available for the MN to terminate the split bearer.

[0133] The MN-CP 710 may identify the best UL primary path based on the indication information and the uplink state information of the MN. The uplink state information of the MN may be collected through the wireless network of the MN. For example, the uplink state information of the MN may include a measurement report received from a terminal (e.g., UE 730) connected to the MN. For example, the MN-CP 710 may indicate that the channel quality of the uplink wireless network provided by the SN is lower than a threshold, and the indication information may indicate that the uplink wireless network provided by the SN is available. The MN-CP 710 may identify the uplink wireless network provided by the SN as the best UL primary path. As another example, the MN-CP 710 may indicate that the channel quality of the uplink wireless network provided by the MN is higher than a threshold, and the indication information may indicate that the uplink wireless network provided by the SN is unavailable. The MN-CP 710 may identify the uplink wireless network provided by the MN as the best UL primary path. As another example, the MN-CP 710 may indicate that the channel quality of the uplink wireless network provided by the MN is higher than a threshold, and the indication information may indicate that the uplink wireless network provided by the SN is available. The MN-CP 710 may identify the currently set primary path as the best UL primary path. When all are available, it may not be advantageous in terms of radio resource management to unnecessarily change the currently set UL primary path.

[0134] In operation S707, the MN-CP 710 may send a bearer context modification request message to the MN-UP 715 via the E1 interface. According to an embodiment, the bearer context modification request confirmation message may include a UL configuration. This is because the UL main path has changed. The UL configuration may indicate whether the MCG can be used for UL services. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the MCG is not used for UL data. The UL configuration may indicate "shared". The term "shared" may indicate that the MCG is used for UL data together with other MCGs. The UL configuration may indicate "only". The term "only" may indicate that only the MCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the UL configuration provided by the SN (i.e., the UL configuration received from operation S703).

[0135] In operation S709, the MN-UP 715 may send a bearer context modification response message to the MN-CP 710 through the E1 interface.

[0136] In operation S711, the MN-CP 710 may send an SN modification request message to the SN-CP 720 through an Xn interface. According to an embodiment, the SN modification request message may include PDU session resource modification information. The PDU session resource information may be configured for the MN terminated split bearer. For example, the PDU session resource modification information may be a "PDU Session Resource Modification Response Info-SN terminated" IE of 3GPP TS 38.423. The IE may include information related to the PDU session resource for a request to modify a DRB configured with an option corresponding to the MN terminated bearer.

[0137] According to an embodiment, the SN modification request message may include a UL configuration. The PDU session resource information of the SN modification request message may include a DRB and a UL configuration corresponding to the DRB. This is because the UL main path has changed. The UL configuration may indicate whether the SCG can be used for UL services. For example, the PDU session resource information may include the parameters shown in Table 5 below.

[0138] [Table 5]

[0139]

[0140] Here, the term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The type of the DRB may be a MN terminated split bearer. The term "UL Configuration" may indicate a UL configuration. The term "UL Configuration" may include information about UL usage in a MN terminated split bearer. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the MCG is not used for UL data. The UL configuration may indicate "shared". The term "shared" may indicate that the MCG and other MCGs are used together for UL data. The UL configuration may indicate "only". The term "only" may indicate that only the MCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the indication information provided by the SN. In operation S713, the SN-CP 720 may send an SN Modification Request Acknowledge message to the MN-CP 710 via the Xn interface.

[0141] In operation S715, the MN-CP 710 may send an RRC reconfiguration message to the UE 730. The RRC reconfiguration message may be configured to carry an SN RRC reconfiguration message. This is because the settings related to the SN have changed. The RRC reconfiguration message may include a PDCP configuration. The PDCP configuration may include information for indicating a UL primary path. For UL data transmission, the PDCP configuration may include information indicating that two or more RLC entities are associated with one PDCP entity (e.g., "moreThanOneRLC" IE of 3GPP TS 38.331). According to an embodiment, the PDCP configuration may include information about the primary path (e.g., "primarypath" IE of 3GPP TS 38.331).

[0142] In operation S717, the UE 730 may send an RRC reconfiguration complete message to the MN-CP 710. The RRC reconfiguration complete message may be configured to carry the SN RRC reconfiguration complete message.

[0143] In operation S719, the MN-CP 710 may send an SN Modification Confirm message to the SN-CP 720 through the Xn interface. The SN Modification Confirm message may be configured to carry an SN RRC Reconfiguration Complete message.

[0144] exist Figure 7a In the embodiment of determining the UL primary path based on the indication information of the MN in the MN termination split bearer, it has been described. According to another embodiment, the indication information can be used to determine the values ​​of other parameters configured by the PDCP and the UL primary path. According to an embodiment, the split threshold (e.g., ul-DataSplitThreshold of 3GPP TS 38.331) configured by the PDCP can be determined based on the indication information.

[0145] exist Figure 7a In the above, operations for configuring the UL main path of the MN termination bearer in a structure in which the base station is divided into DU, CU-UP, and CU-CP have been described. However, the example embodiments may also be applied to a structure in which the base station is divided into only DU and CU (e.g., a structure in which CU-CP and CU-UP are not separated) or a structure in which the base station is not separated. In such occasions, some operations may be omitted. For example, in a structure in which CU-CP and CU-UP are not separated, operations S707 and S709 may be omitted.

[0146] Figure 7b Another example of signaling for controlling the UL path of a MN-terminated split bearer according to an embodiment is shown. Figure 7a In the embodiment, the change in the UL primary path is identified in response to the MN-CP 710 receiving the indication information. However, the operation of changing the optimal primary path of the MN-CP 710 may be performed after the SN modification request process. The MN-CP 710, the MN-UP 715, the SN-CP 720, the SN-UP 725, or the UE 730 is shown as a node for UL path control. For each node and the above reference Figures 2 to 5 The description of the interfaces between the described nodes may be applied to the MN-CP 710 , the MN-UP 715 , the SN-CP 720 , the SN-UP 725 , or the UE 730 .

[0147] Reference Figure 7b In operation S751, the SN-CP 720 may receive a measurement report or a medium access control (MAC) indication. Operation S751 may correspond to Figure 7a Operation S701. Figure 7a The description of operation S701 in FIG. 1 may also be applied to operation S751 in the same or similar manner.

[0148] In operation S753, the SN-CP 720 may send an SN modification request message to the MN-CP 710 through the Xn interface. According to an embodiment, the SN modification request message may include indication information. The indication information may include information about the use of the UL path. The indication information may indicate whether the MCG resource or the SCG resource is available for the UL path in the split bearer, that is, its availability. Operation S753 may correspond to Figure 7a Operation S703. Figure 7a The description of operation S703 in may also be applied to operation S753 in the same or similar manner.

[0149] In operation S755, the MN-CP 710 may determine that the UL path is to be changed. The MN-CP 710 may identify the current UL primary path. The current UL primary path may refer to the UL primary path configured for the MN terminated split bearer in the UE 730. The MN-CP 710 may identify the best UL primary path. When the current UL primary path is different from the best UL primary path, the MN-CP 710 may determine that the UL path is to be changed. Conversely, when the current UL primary path and the best UL primary path are the same, the MN-CP 710 may determine not to change the UL path. Figure 7b In the present invention, signaling in which an operation according to a UL path change is performed independently of an SN modification requirement procedure is described. Figure 7bThe operation of determining the UL path change is shown to be performed during the SN modification requirement procedure, but the embodiments of the present disclosure are not limited thereto. According to an embodiment, operation S755 may be performed after operation S757. Even if the SN-CP 720 sends instruction information to the MN-CP 710 through the SN modification requirement procedure, the MN-CP 710 may determine the UL configuration of the split bearer through an independent procedure (e.g., an SN modification request procedure). Thus, the MN-CP 710 may first perform operation S757.

[0150] In operation S757, the MN-CP 710 may send an SN modification confirmation message to the SN-CP 720 through the Xn interface. Since there is no change in the UL primary path during the SN modification request procedure, it is not required to send an RRC message to change the UL path. Thus, the MN-CP 710 may send an SN modification confirmation message to the SN-CP 720 in response to the SN modification request message.

[0151] In operation S759, the MN-CP 710 may send an SN modification request message to the SN-CP 720 through an Xn interface. According to an embodiment, the SN modification request message may include PDU session resource modification information. The PDU session resource information may be configured for the MN terminated split bearer. For example, the PDU session resource modification information may be a "PDU Session Resource Modification Response Info-SN terminated" IE of 3GPP TS 38.423. The IE may include information related to the PDU session resource for a request to modify a DRB configured with an option corresponding to the MN terminated bearer.

[0152] According to an embodiment, the SN modification request message may include a UL configuration. The PDU session resource information of the SN modification request message may include a DRB and a UL configuration corresponding to the DRB. This is because the UL main path has changed. The UL configuration may indicate whether the SCG can be used for UL services. For example, the PDU session resource information may include the parameters shown in Table 6 below.

[0153] [Table 6]

[0154]

[0155] Here, the term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The type of the DRB may be a MN terminated split bearer. The term "UL Configuration" may indicate a UL configuration. The term "UL Configuration" may include information about UL usage in a MN terminated split bearer. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the MCG is not used for UL data. The UL configuration may refer to "shared". The term "shared" may indicate that the MCG and other MCGs are used together for UL data. The UL configuration may indicate "only". The term "only" may indicate that only the MCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the indication information provided by the SN. In operation S761, the SN-CP 720 may send a bearer context modification request message to the SN-UP 725 via an E1 interface. The bearer context modification request message may include the UL configuration of the SCG in the split bearer (e.g., the UL configuration IE of TS 38.463 of 3GPP). This is because the UL main path has changed. The UL configuration may indicate whether the SCG is available for UL traffic. For example, the UL configuration may indicate "no data". The term "no data" may indicate that the SCG is not available for UL data. The UL configuration may refer to "shared". The term "shared" may indicate that the SCG and other SCGs may be available for UL data together. The UL configuration may indicate "only". The term "only" may indicate that only the SCG is used for UL data. According to an embodiment, the UL configuration may be determined not to conflict with the indication information provided by the MN.

[0156] In operation S763, the SN-UP 725 may send a bearer context modification response message to the SN-CP 720 through the E1 interface.

[0157] In operation S765, the SN-CP 720 may send an SN Modification Request Acknowledge message to the MN-CP 710 through the Xn interface.

[0158] In operation S767, the MN-CP 710 may send a bearer context modification request message to the MN-UP 715 via the E1 interface. Operation S767 may correspond to Figure 7a Operation S707. Figure 7a The description of operation S707 in may also be applied to operation S767 in the same or similar manner.

[0159] In operation S769, the MN-UP 715 may send a bearer context modification response message to the MN-CP 710 through the E1 interface.

[0160] In operation S771, MN-CP 710 may send an RRC reconfiguration message to UE 730. Operation S771 may correspond to Figure 7a Operation S715. Figure 7a The description of operation S715 in may also be applied to operation SS771 in the same or similar manner.

[0161] In operation S773, UE 730 may send an RRC reconfiguration complete message to MN-CP 710. Operation S773 may correspond to Figure 7a Operation S717. Figure 7a The description of operation S717 in may also be applied to operation S773 in the same or similar manner.

[0162] In operation S775, the MN-CP 710 may send an SN reconfiguration complete message to the SN-CP 720 through the Xn interface. The SN reconfiguration complete message may be configured to carry an SN RRC reconfiguration complete message.

[0163] exist Figure 7b In the embodiment of determining the UL primary path based on the indication information of the MN in the MN termination split bearer, it has been described. According to another embodiment, the indication information can be used to determine the values ​​of other parameters configured by the PDCP and the UL primary path. According to an embodiment, the split threshold configured by the PDCP (for example, ul-DataSplitThreshold of TS 38.331 of 3GPP) can be determined based on the indication information.

[0164] In addition, Figure 7b In the above, operations for configuring the UL main path of the MN termination bearer in a structure in which the base station is divided into DU, CU-UP, and CU-CP have been described. However, the example embodiments may also be applied to a structure in which the base station is divided into only DU and CU (e.g., a structure in which CU-CP and CU-UP are not separated), or may be applied to a structure in which the base station is not separated. In this case, some operations may be omitted. For example, in a structure in which CU-CP and CU-UP are not separated, operations S761, S763, S767, and S769 may be omitted.

[0165] Figure 8a 810, MN-DU 815, SN-CP 820 or UE 830 are shown as nodes for path control. For each node and the above reference Figures 2 to 5The description of the interface between the described nodes may be applied to the MN-CP 810 , the MN-DU 815 , the SN-CP 820 , or the UE 830 .

[0166] Reference Figure 8a , in operation S801, the MN-DU 815 may detect that a condition of a cell group has changed. The condition of a cell group may refer to a parameter for a cell group associated with a current split bearer (e.g., an SN terminated split bearer) or a specified metric for a cell group. According to an embodiment, the condition of a cell group may be configured based on a channel-related metric such as radio resource usage in each cell group (e.g., MCG or SCG), radio resource availability in each cell group, or channel quality of a cell (e.g., PCell or PSCell) in each cell group. In addition, according to an embodiment, the condition of a cell group may be configured based on a device condition of a node providing the cell group. For example, when the device of the current node has a mechanical defect or it is difficult to provide an uplink frequency, the cell group of the current node may not be suitable as a UL main path.

[0167] The above examples, combinations of these examples, or metrics with similar technical meanings may be defined as conditions for a cell group. The MN-DU 815 may detect changes in the conditions for a cell group. According to an embodiment, the MN-DU 815 may identify that a parameter or metric related to an MCG resource has changed.

[0168] When the conditions of the cell group change, the MN-DU 815 is required to inform the CU of the conditions of the cell group. This is because the PDCP is set in the CU. The MN-DU 815 can inform the CU whether the current cell group is sufficient to support the UL path to help the CU determine whether to change the UL primary path.

[0169] In operation S803, the MN-DU 815 may send a UE context modification required message to the MN-CP 810 via the F1 interface. For example, the UE context modification required message may be referred to as a UE context modification message. The MN-DU 815 may generate indication information for notifying the condition of the current cell group. When the state of the MCG resource changes, the MN-DU 815 may generate indication information for informing the CU of the availability of UL usage of the MCG. The MN-DU 815 may generate a UE context modification required message including the indication information. According to an embodiment, the UE context modification required message may include a DRB and indication information corresponding to the DRB. The indication information may indicate whether the MCG resource can be used as a UL path in the DRB. For example, the UE context modification required message may include parameters as shown in Table 7 below.

[0170] [Table 7]

[0171]

[0172] In this document, the term "Message Type" may indicate the type of message sent (e.g., initiation message, successful result, unsuccessful result). The term "gNB-CU UE F1AP ID" may indicate an ID for identifying a UE in the F1AP interface of a gNB-CU. The term "gNB-DU UE F1AP ID" may indicate an ID for identifying a UE in the F1AP interface of a gNB-DU. The term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The DRB may be an SN-terminated split bearer. The term "UL Path Usage Indication" may indicate indication information. The term "UL Path Usage Indication" may indicate the availability of UL usage related to the MCG resources of the MN in the SN-terminated split bearer. According to an embodiment, the indication information may simply indicate whether the UL usage related to the MCG resources is available. According to another embodiment, the indication information may indicate one of the specified values. The specified value may indicate "unavailable", "shared", and "only". The term "unavailable" may indicate that the MCG is not available for UL data. The indication information may indicate "shared". The term "shared" may indicate that the MCG can be used for UL data together with other MCGs. The indication information may indicate "only". The term "only" may indicate that the MCG can be used for UL data. According to another embodiment, the indication information may include both whether the UL related to the MCG resources is available and a metric (e.g., channel quality) related to the current uplink state when UL use is available. In operation S805, the MN-CP 810, the SN-CP 820, and the UE 830 may perform a UL path change procedure for the radio bearer. According to an embodiment, the radio bearer may be an SN terminated split bearer. For Figure 6a to Figure 6b The description of may also be applied to MN-CP 810, SN-CP 820 and UE 830. According to an embodiment, the radio bearer may be a MN-terminated split bearer. Figure 7a to Figure 7b The description may also be applied to MN-CP 810, SN-CP 820 and UE 830.

[0173] In operation S807, the MN-CP 810 may send a UE Context Modification Confirm message to the MN-DU 815 through the F1 interface.

[0174] Figure 8b810, SN-CP 820, SN-DU 825, or UE 830 are shown as nodes for path control. For each node and the above reference Figures 2 to 5 The description of the interface between the described nodes may be applied to the MN-CP 810, the SN-CP 820, the SN-DU 825, or the UE 830.

[0175] Reference Figure 8b , in operation S851, the SN-DU 825 may detect that the condition of the cell group has changed. The condition of the cell group may refer to a parameter for a cell group associated with the current split bearer (e.g., a MN terminated split bearer) or a specified metric for a cell group. According to an embodiment, the condition of the cell group may be configured based on channel-related metrics such as radio resource usage in each cell group (e.g., MCG or SCG), radio resource availability in each cell group, and channel quality of cells in each cell group (e.g., PCell or PSCell). In addition, according to an embodiment, the condition of the cell group may be configured based on the device status of the node providing the cell group. For example, when there is any mechanical defect in the device of the current node or the device has difficulty in providing uplink frequency, the cell group of the current node will not be suitable as the UL main path.

[0176] The above examples, combinations of these examples, or metrics similar to these in technical meaning may be defined as conditions for a cell group. The SN-DU 825 may detect changes in the conditions for a cell group. According to an embodiment, the SN-DU 825 may identify that a parameter or metric related to an MCG resource has changed.

[0177] When the cell group change condition is met, the SN-DU 825 is required to inform the CU of the cell group condition. This is because the PDCP is set in the CU. The SN-DU 825 can inform the CU whether the current cell group is sufficient to support the UL path to help the CU determine whether to change the UL primary path.

[0178] In operation S853, the SN-DU 825 may send a UE context modification request message to the SN-CP 820 via the F1 interface. For example, the UE context modification request message may be referred to as a UE context modification message. The SN-DU 825 may generate indication information for notifying the conditions of the current cell group. When the conditions of the SCG resources change, the SN-DU 825 may generate indication information for informing the CU of the availability of UL usage of the SCG. The SN-DU 825 may generate a UE context modification request message including the indication information. According to an embodiment, the UE context modification confirmation message may include a DRB and indication information corresponding to the DRB. The indication information may indicate whether the SCG resources in the DRB can be used as a UL path. For example, the UE context modification confirmation message may include parameters as shown in Table 8 below.

[0179] [Table 8]

[0180]

[0181] In this document, the term "Message Type" may indicate the type of message sent (e.g., initiation message, successful result, unsuccessful result). The term "gNB-CU UE F1AP ID" may indicate an ID for identifying a UE in the F1AP interface of a gNB-CU. The term "gNB-DU UE F1AP ID" may indicate an ID for identifying a UE in the F1AP interface of a gNB-DU. The term "DRB ID" may indicate an ID for identifying a DRB. The term "DRB ID" may indicate a DRB. The DRB may be a MN terminated split bearer. The term "UL Path Usage Indication" may indicate indication information. The term "UL Path Usage Indication" may indicate the availability of UL usage associated with SCG resources of the SN in the MN terminated split bearer. According to an embodiment, the indication information may simply indicate whether the UL usage associated with the SCG resources is available. According to another embodiment, the indication information may indicate one of the specified values. The specified value may indicate "unavailable", "shared", and "only". The term "unavailable" may indicate that the SCG is not available for UL data. The indication information may indicate "shared". The term "shared" may indicate that the SCG may be available for UL data together with other SCGs. The indication information may indicate "only". The term "only" may indicate that the SCG may be available for UL data. According to another embodiment, the indication information may include both whether the UL associated with the SCG resources is available and a metric (e.g., channel quality) associated with the current uplink state when the UL is available. In operation S855, the MN-CP 810, the SN-CP 820, and the UE 830 may perform a UL path change procedure for the radio bearer. According to an embodiment, the radio bearer may be an SN terminated split bearer. Figure 6a to Figure 6b The description of may also be applied to MN-CP 810, SN-CP 820 and UE 830. According to an embodiment, the radio bearer may be a MN-terminated split bearer. Figure 7a to Figure 7b The description may also be applied to MN-CP 810, SN-CP 820, and UE 830.

[0182] In operation S857, the SN-CP 820 may send a UE Context Modification Confirm message to the SN-DU 825 through the F1 interface.

[0183] exist Figures 6a to 8bIn the description, an IE (e.g., UL Path Usage Indication IE) indicating the availability of the UL path in the corresponding node included in the previously defined message has been described, but the embodiment is not limited thereto. In addition to the new IE, a new message may also be defined. A separate message may be defined for resource coordination between the MN and the SN. That is, the new message to be described later may be sent not only from the node to the node to recommend the UL main path, but also for other operations requiring resource adjustment. For example, when selecting the best band combination in the NR-DC scenario, the MN is required to know the band information supported in the SN and the information about the neighboring cells operating in the SN. Therefore, the MN can receive a message related to the wireless status in the SN from the SN. The MN can select an appropriate PSCell to optimize the band combination of NR-DC and NR SA.

[0184] In the following, reference will be made to Fig. 9 and Fig.10 A message for indicating availability of a UL path for use according to an example embodiment is described.

[0185] Fig. 9 An example of a message for controlling the UL path of the SN-terminated split bearer according to an embodiment is shown. Figures 2 to 5 The description of the interfaces between the described nodes may be applied to the MN 910 , the SN 920 , and the UE 930 .

[0186] Reference Fig. 9 , the wireless communication environment may include MN 910, SN 920, UE 930, UPF 940 and AMF 950. MN 910 as an NG-RAN node may provide an access network to UE 930. SN 920 as an NG-RAN node may provide an access network to UE 930. SN termination split bearer may be configured for UE 930. PDCP may be configured in SN 920, and a MAC layer, an RLC layer and a physical layer may be configured in each of MN 910 and SN 920. The core network may include a plurality of entities. UPF 940 of the core network is a network entity used as a gateway for transmitting user data (e.g., packet data unit (PDU)) to a data network (DN). AMF 950 of the core network is a network entity that manages the mobility of a terminal (e.g., UE 930).

[0187] In operation S901, the MN 910 may receive a measurement report or a medium access control (MAC) indication. The measurement report may include at least one of a measurement result for a serving cell of the MN or a measurement result for a neighboring cell. The measurement result may indicate a radio state of an uplink channel of the MN. The MAC indication may include a downlink data delivery state (DDDS). According to an embodiment, the MN 910 may determine whether a UL path using an MCG is available based on at least one of the measurement report or the MAC indication.

[0188] In operation S903, the MN 910 may send a resource usage notification message to the SN 920 through an Xn interface. According to an embodiment, the resource usage notification message may include indication information. The indication information may include information about the use of the UL path. The indication information may indicate whether MCG resources or SCG resources can be used for the UL path in the split bearer, i.e., availability (or preference). The PDCP of the SN-terminated split bearer is located in the SN 920, and the RLC and MAC of the SN-terminated split bearer are located in both the MN 910 and the SN 920. In order to determine the best UL primary path, the SN 920 requires information about the uplink radio channel in the MN 910 other than the SN 920. The MN 910 may determine whether the UL path using the MCG is available. As the determination of the MN 910 is provided to the SN 920, the SN 920 may identify the best UL primary path more accurately.

[0189] According to an embodiment, the resource usage notification message may include the following parameters as shown in Table 9.

[0190] [Table 9]

[0191]

[0192]

[0193] In this document, the term "Message Type" may indicate the type of message sent (e.g., initiation message, successful result, unsuccessful result). The term "M-NG-RAN node UE X1AP ID" refers to an ID used to identify the UE in the X1AP interface of the M-NG-RAN node. The term "S-NG-RAN node X1AP ID" may indicate an ID used to identify the UE in the X1AP interface of the S-NG-RAN node. The term "UE Context Level UL Path Usage Indication" may indicate the level of resource units for setting the UL primary path. The term "PDU Session Level UL Path Usage Indication" may indicate the use of the UL path in units of PDU sessions. The term "QoS Flow Identifier" may indicate an ID used to identify a QoS flow. The term "UL Path Usage Indication" may indicate indication information. The term "UL Path UsageIndication" may indicate a preference for UL usage related to the MCG resources of the MN 1010 in the SN terminated split bearer. According to an embodiment, the indication information may simply indicate whether the UL usage associated with the MCG resources is preferred. According to another embodiment, the indication information may indicate one of the specified values. The specified value may indicate "non-preferred", "shared" and "only". The term "non-preferred" may indicate that the use of the MCG resources is not preferred for UL data. The indication information may indicate "shared". The term "shared" may indicate that the MCG and other MCGs preferably use the UL data together. The indication information may indicate "only". The term "only" may indicate that the MCG is available for UL data. According to another embodiment, the indication information may include both whether the UL usage associated with the MCG resources is preferred and a metric (e.g., channel quality) related to the current uplink state when the UL usage is available. Referring to the above-mentioned embodiments, the preference for the UL path using the MCG resources or the SCG resources has been described as an example, but such preference may be replaced by its availability. According to an embodiment, the indication information may simply indicate whether the UL usage using the MCG resources is available. In addition, at least some of the above-mentioned parameters may be omitted for the efficiency of its message format or policy.

[0194] In operation S905, the SN 920 may trigger a UL path change. The SN 920 may determine that the UL path is to be changed. In order to determine the path change, the SN 920 may identify the current UL primary path. The current UL primary path may refer to the UL primary path configured for the SN terminated split bearer in the UE 930. The SN 920 may identify the best UL primary path. When the current UL primary path is different from the best UL primary path, the SN 920 may determine that the UL path is to be changed. According to an embodiment, the SN 920 may identify the best UL primary path based on the indication information. The indication information may indicate the availability or preference of the uplink wireless network provided by the MN 910.

[0195] In operation S907, SN 920 may send an SN modification required message to MN 910. For example, the SN modification required message may be referred to as an SN modification message. According to an embodiment, the SN modification required message may include PDU session resource modification information. PDU session resource information may be configured for SN terminated split bearer. For example, the PDU session resource modification information may be the "PDU Session Resource Modification Required Info-SN terminated" IE of 3GPP TS38.423. The IE may include information related to PDU session resources for a request to modify a DRB configured with an option corresponding to an SN terminated bearer. The request may be initiated by an S-NG-RAN node. According to an embodiment, the PDU session resource information may include a DRB and indication information corresponding to the DRB. The indication information may indicate whether MCG resources are available as a UL path in the DRB. For example, the PDU session resource information may include parameters as shown in Table 4.

[0196] In operation S909, the MN 910 may perform an SN modification procedure. The SN modification procedure may be selectively performed. The SN modification procedure of the MN 910 may include sending an SN modification request message using an X2 interface and receiving an SN modification request completion message using an X2 interface. The MN 910 may send an SN modification request message to the SN 920. The MN 910 may receive an SN modification request completion message from the SN 920.

[0197] In operation S911, the MN 910 may send an RRC reconfiguration message to the UE 930. The RRC reconfiguration message may be configured to carry an SN RRC reconfiguration. This is because the settings related to the SN have changed. The RRC reconfiguration message may include a PDCP configuration. The PDCP configuration may include information for indicating a UL primary path. For UL data transmission, the PDCP configuration may include information indicating that two or more RLC entities are associated with one PDCP entity (e.g., "moreThanOneRLC" IE of 3GPP TS38.331). According to an embodiment, the PDCP configuration may include information about the primary path (e.g., "primarypath" IE of 3GPP TS 38.331).

[0198] In operation S913, the UE 930 may send an RRC reconfiguration complete message to the MN 910. The RRC reconfiguration complete message may be configured to carry the SN RRC reconfiguration complete message.

[0199] In operation S915, the MN 910 may send an SN modification confirmation message to the SN 920 through the Xn interface. The SN modification confirmation message may be configured to carry an SN RRC reconfiguration completion message.

[0200] although Fig. 9 It is shown that the MN 910 performs the SN modification procedure, but the embodiments of the present disclosure are not limited thereto. According to another embodiment, the SN modification procedure may be omitted.

[0201] Fig.10 An example of a message for controlling the MN to terminate the UL path of the split bearer according to an embodiment is shown. Figures 2 to 5 The description of the interfaces between the described nodes may also be applied to the MN 1010 , the SN 1020 , and the UE 1030 .

[0202] Reference Fig.10, the wireless communication environment may include MN 1010, SN 1020, UE 1030, UPF 1040 and AMF 1050. MN 1010 as an NG-RAN node may provide an access network to UE 1030. SN 1020 as an NG-RAN node may provide an access network to UE 1030. For UE 1030, MN termination split bearer may be configured. PDCP may be configured in SN 1020, and a MAC layer, an RLC layer, and a physical layer may be configured in each of MN 1010 and SN 1020. The core network may include a plurality of entities. UPF 1040 of the core network is a network entity used as a gateway for transmitting user data (e.g., packet data unit (PDU)) to a data network (DN). AMF 1050 of the core network is a network entity that manages the mobility of a terminal (e.g., UE 1030).

[0203] In operation S1001, the SN 1020 may receive a measurement report or a medium access control (MAC) indication. The measurement report may include at least one of a measurement result for a serving cell of the MN or a measurement result for a neighboring cell. The measurement result may indicate a radio state of an uplink channel of the MN. The MAC indication may include a downlink data delivery state (DDDS). According to an embodiment, the MN 1010 may determine whether a UL path using an MCG is available based on at least one of the measurement report or the MAC indication.

[0204] In operation S1003, the SN 1020 may send a resource usage notification message to the MN 1010 through an Xn interface. According to an embodiment, the resource usage notification message may include indication information. The indication information may include information about the use of the UL path. The indication information may indicate whether MCG resources or SCG resources are available for the UL path in the split bearer, i.e., availability (or preference). The PDCP of the MN terminated split bearer is located in the MN 1010, and the RLC and MAC of the MN terminated split bearer are located in both the MN 1010 and the SN 1020. In order to determine the best UL primary path, the SN 1020 requires information about the uplink radio channel in the MN 1010 other than the SN 1020. The SN 1020 may determine whether the UL path using the MCG is available. As the SN 1020 provides the result of the determination to the MN 1010, the MN 1010 may identify the best UL primary path more accurately.

[0205] According to an embodiment, the resource usage notification message may include parameters as shown in Table 10 as follows.

[0206] [Table 10]

[0207]

[0208] In this document, the term "Message Type" may indicate the type of message sent (e.g., initiation message, successful result, unsuccessful result). The term "M-NG-RAN node UE X1AP ID" may refer to an ID used to identify a UE in the X1AP interface of an M-NG-RAN node. The term "S-NG-RAN node X1AP ID" may indicate an ID used to identify a UE in the X1AP interface of an S-NG-RAN node. The term "UE Context Level UL Path Usage Indication" may indicate the level of resource units for setting a UL primary path. The term "PDU Session Level UL Path Usage Indication" may indicate the use of a UL path in units of PDU sessions. The term "QoS Flow Identifier" may indicate an ID used to identify a QoS flow. The term "UL Path Usage Indication" may indicate indication information. The term "UL Path UsageIndication" may indicate a preference for UL usage related to MCG resources of SN 1020 in an MN terminated split bearer. According to an embodiment, the indication information may simply indicate whether the UL usage associated with the MCG resource is preferred. According to another embodiment, the indication information may indicate one of the specified values. The specified value may indicate "non-preferred", "shared" and "only". The term "non-preferred" may indicate that the use of the MCG resource is not preferred for UL data. The indication information may indicate "shared". The term "shared" may indicate that the MCG and other MCGs prefer to use UL data together. The indication information may indicate "only". The term "only" may indicate that the MCG is available for UL data. According to another embodiment, the indication information may include both whether the UL usage associated with the MCG resource is preferred and a metric (e.g., channel quality) related to the current uplink state when the UL usage is available. In the above-mentioned embodiments, the preference for the UL path using the MCG resource or the SCG resource has been described as an example, but its availability may be used instead of the preference (e.g., the indication information may indicate "unavailable", "shared" or "only"). According to an embodiment, the indication information may simply indicate whether the UL using the MCG resource is available. In addition, at least some of the above-mentioned parameters may be omitted for the efficiency of its message format or policy.

[0209] In operation S1005, MN 1010 may trigger a UL path change. MN 1010 may determine that the UL path is to be changed. MN 1010 may identify a current UL primary path. The current UL primary path may refer to a UL primary path configured for MN termination split bearer in UE 1030. MN 1010 may identify an optimal UL primary path. When the current UL primary path is different from the optimal UL primary path, MN 1010 may determine that the UL path is to be changed. According to an embodiment, MN 1010 may identify the optimal UL primary path based on indication information. The indication information may indicate the availability or preference of an uplink wireless network provided by SN 1020.

[0210] In operation S1007, the MN 1010 may send an SN modification request message to the SN 1020 through an Xn interface. According to an embodiment, the SN modification request message may include PDU session resource modification information. The PDU session resource information may be configured for the MN terminated split bearer. For example, the PDU session resource modification information may be a "PDU Session Resource Modification Response Info-SN terminated" IE of 3GPP TS 38.423. The IE may include information related to the PDU session resource for a request to modify a DRB configured with an option corresponding to the MN terminated bearer.

[0211] According to an embodiment, the SN modification request message may include a UL configuration. The PDU session resource information of the SN modification request message may include a DRB and a UL configuration corresponding to the DRB. This is because the UL main path has changed. The UL configuration may indicate whether the SCG is available for UL services. For example, the PDU session resource information may include parameters as shown in Table 5 above.

[0212] In operation S1009, the SN 1020 may send an SN Modification Request Confirm message to the MN 1010 through the Xn interface.

[0213] In operation S1011, MN 1010 may send an RRC reconfiguration message to UE 1030. The RRC reconfiguration message may be configured to carry an SN RRC reconfiguration. This is because the settings related to the SN have changed. The RRC reconfiguration message may include a PDCP configuration. The PDCP configuration may include information for indicating a UL primary path. For UL data transmission, the PDCP configuration may include information indicating that two or more RLC entities are associated with one PDCP entity (e.g., 'moreThanOneRLC' IE of 3GPP TS 38.331). According to an embodiment, the PDCP configuration may include information about the primary path (e.g., 'primarypath' IE of 3GPP TS 38.331).

[0214] In operation S1013, UE 1030 may send an RRC reconfiguration complete message to MN 1010. The RRC reconfiguration complete message may be configured to carry an SN RRC reconfiguration complete message.

[0215] In operation S1015, the MN 1010 may send an SN reconfiguration complete message to the SN 1020 through an Xn interface. The SN reconfiguration complete message may be configured to carry an SN RRC reconfiguration complete message.

[0216] Fig.11 The functional configuration of the device as an MN or SN according to an embodiment is shown. The device 1100 as an MN or SN may be a base station or a partial element of a base station. According to an embodiment, the device may be a central unit (CU) of the MN or SN. According to an embodiment, the device may be a distributed unit (DU) of the MN or SN. According to an embodiment, the device may be a CU-CP (control plane) of the MN or SN. According to an embodiment, the device may be a CU-UP (user plane) of the MN or SN.

[0217] Reference Fig.11 , the device 1100 may include at least one transceiver 1110 , at least one memory 1120 , and at least one processor 1130 .

[0218] The transceiver 1110 can perform functions for sending and receiving signals through a wireless channel. For example, the transceiver 1110 can perform a conversion function between a baseband signal and a bit string according to the physical layer specification of the system. For example, when data is transmitted, the transceiver 1110 generates a complex symbol by encoding and modulating the transmission bit string. In addition, when data is received, the transceiver 1110 recovers the received bit string by demodulating and decoding the baseband signal. In addition, the transceiver 1110 can up-convert the baseband signal into a radio frequency (RF) band signal to transmit the RF band signal through an antenna, and down-convert the RF band signal received by the antenna into a baseband signal.

[0219] For this purpose, the transceiver 1110 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. In addition, the transceiver 1110 may include multiple transmit / receive paths. In addition, the transceiver 1110 may include at least one antenna array having multiple antenna elements. In terms of hardware, the transceiver 1110 may include a digital unit and an analog unit, wherein the analog unit may include multiple subunits according to operating power, operating frequency, etc.

[0220] The transceiver 1110 sends and receives signals as described above. Therefore, the transceiver 1110 may be referred to as a "transmitter unit", "receiver unit" or "transceiver unit". In addition, throughout the following description, the transmission and reception performed via a wireless channel, a backhaul network, an optical cable, an Ethernet, and other wired paths are used to include the meaning that the above-mentioned processing is performed by the transceiver 1110. According to an embodiment, the transceiver 1110 may provide an interface for communicating with other nodes in the network. In other words, the transceiver 1110 may convert a bit string sent from the device 1100 to another node (such as, for example, another access node, another base station, an upper node, a core network, etc.) into a physical signal, and convert a physical signal received from another node into a bit string.

[0221] The memory 1120 may store data such as, for example, basic programs, applications, and setting information for operating the device 1100. The memory 1120 may store various data used by at least one component (e.g., the transceiver 1110 or the processor 1130). The data may include, for example, software and input data or output data for instructions related thereto. The memory 1120 may include a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. In addition, the memory 1120 may provide data stored therein according to a request of the processor 1130.

[0222] The processor 1130 may control the overall operation of the device 1100. For example, the processor 1130 records or reads data in the memory 1120. For example, the processor 1130 transmits and receives signals through the transceiver 1110. Fig.11 One processor is shown, but the embodiments of the present disclosure are not limited thereto. The device 1100 may include at least one processor for executing the example embodiments. The processor 1130 may be referred to as a control unit or a control means, and may include a processing circuit. According to an embodiment, the processor 1130 may control the device 1100 to perform at least one of the operations or methods according to the example embodiments.

[0223] According to an example embodiment, a method performed by a first node as a master node (MN) in a dual connection may include receiving an SN modification request message from a second node as a secondary node (SN) via an Xn interface. The SN modification request message may include indication information for a MN terminated split bearer. The indication information may indicate the availability of UL usage at the SN. The method may include identifying an uplink (UL) primary path of the MN terminated split bearer based on the indication information about the MN terminated split bearer. The method may include sending information indicating the UL primary path to a terminal. The UL primary path may be associated with one of a primary cell group (MCG) of the MN and a secondary cell group (SCG) of the SN.

[0224] According to an embodiment, the MN terminated split bearer may be a data radio bearer (DRB) having both MCG resources related to the MN and SCG resources related to the SN, and the indication information may indicate whether the SCG resources are available for UL transmission at the SN.

[0225] According to an embodiment, the method may further include: in the case of detecting a change in the UL primary path, sending an SN modification request message to the second node working as the SN through the Xn interface. The method may further include receiving an SN modification request confirmation message from the second node working as the SN through the Xn interface. The SN modification request message may include a UL configuration for the MN terminated split bearer. The UL configuration may indicate a configuration method for how to configure a UL PDCP (Packet Data Convergence Protocol) related to the MN terminated split bearer in the SN. The UL configuration may be determined based on the indication information.

[0226] According to an embodiment, the method may further include sending an SN modification confirmation message to the base station serving as the SN through an Xn interface when no change in the UL primary path is detected.

[0227] According to an embodiment, the method may further include: in the case of detecting a change in the UL primary path, sending a bearer context modification request message to the central unit-user plane (CU-UP) of the MN through the E1 interface. The method may further include receiving a bearer context modification response message from the CU-UP of the MN through the E1 interface. The bearer context modification request message may include an UL configuration for the MN terminated split bearer. The UL configuration may indicate that the MCG is not used for uplink data, that the MCG is used for uplink data together with the SCG, or that only the MCG is used for uplink data.

[0228] According to an example embodiment, a method performed by a second node operating as a secondary node (SN) in a dual connection may include obtaining uplink state information through a measurement report or a medium access control (MAC) indication from a user equipment (UE). The method may include generating indication information for a MN terminated split bearer based on the uplink state information. The indication information may indicate the availability of uplink (UL) use at the SN. The method may include sending an SN modification request message to a first node operating as a primary node (MN) via an Xn interface. The indication information for the MN terminated split bearer may be used to identify the UL primary path of the MN terminated split bearer. The UL primary path may be associated with one of the primary cell group (MCG) of the MN and the secondary cell group (SCG) of the SN.

[0229] According to an embodiment, the MN terminated split bearer may be a data radio bearer (DRB) having both MCG resources related to the MN and SCG resources related to the SN. The indication information may indicate whether the SCG resources are available for UL transmission in the SN.

[0230] According to an embodiment, the method may further include receiving an SN modification request message from a base station operating as a MN via an Xn interface. The method may further include sending an SN modification request confirmation message to a base station operating as a MN via an Xn interface. The SN modification request message may include a UL configuration for a MN terminated split bearer. The UL configuration may indicate a configuration method for how to configure a UL PDCP (Packet Data Convergence Protocol) related to a MN terminated split bearer in the SN. The UL configuration may be associated with the indication information. Receipt of the SN modification request message may indicate a change in the UL primary path.

[0231] According to an embodiment, the method may further include receiving an SN modification confirmation message from the base station serving as the MN through an Xn interface.

[0232] According to an embodiment, the method may further include sending a bearer context modification request message to a central unit (CU)-UP (user plane) of the SN via an E1 interface. The method may further include receiving a bearer context modification response message from the CU-UP of the SN via an E1 interface. The bearer context modification request message may include an UL configuration for a MN terminated split bearer. The UL configuration may indicate that MCG resources are not used for uplink data, that only MCG resources are used for uplink data, or that both MCG resources and SCG resources are used for uplink data.

[0233] According to an example embodiment, a device of a first node operating as a master node (MN) in a dual connection may include at least one transceiver and at least one processor directly or indirectly coupled to the at least one transceiver. At least one processor may be configured to receive an SN modification message from a second node operating as a secondary node (SN) via an Xn interface. The SN modification message may include indication information for MN termination split bearer. The indication information may indicate the availability of uplink (UL) usage at the SN. At least one processor may be configured to identify the UL primary path of the MN termination split bearer based on the indication information for the MN termination split bearer. At least one processor may be configured to send information indicating the UL primary path to a user equipment (UE). The UL primary path may be associated with one of the primary cell group (MCG) of the MN and the secondary cell group (SCG) of the SN.

[0234] According to an embodiment, the MN terminated split bearer may be a data radio bearer (DRB) having both MCG resources associated with the MN and SCG resources associated with the SN. The indication information may indicate whether the SCG resources are available for UL transmission at the SN.

[0235] According to an embodiment, at least one processor may be further configured to send an SN modification request message to a base station as the SN through an Xn interface when a change in the UL primary path is detected. At least one processor may be further configured to receive an SN modification request confirmation message from the base station as the SN through an Xn interface. The SN modification request message may include a UL configuration for a MN terminated split bearer. The UL configuration may indicate a configuration device on how to configure a UL PDCP related to a MN terminated split bearer in the SN. The UL configuration may be determined based on the indication information.

[0236] According to an embodiment, at least one processor may be further configured to send an SN modification confirmation message to the base station serving as the SN through an Xn interface when no change in the UL primary path is detected.

[0237] According to an embodiment, at least one processor may be further configured to send a bearer context modification request message to a central unit (CU)-user plane (UP) of the MN via an E1 interface when a change in the UL primary path is detected. At least one processor may be further configured to receive a bearer context modification response message from the CU-UP of the MN via an E1 interface. The bearer context modification request message may include an UL configuration for a MN terminated split bearer. The UL configuration may indicate that MCG resources are not used for uplink data, only MCG resources are used for uplink data, or both MCG resources and SCG resources are used for uplink data.

[0238] According to an example embodiment, a device of a second node working as a secondary node (SN) in a dual connection may include at least one transceiver and at least one processor directly or indirectly coupled to the at least one transceiver. At least one processor may be configured to obtain uplink state information through a measurement report or a medium access control (MAC) indication from a user equipment (UE). At least one processor may be configured to generate indication information for MN termination split bearer based on the uplink state information. The indication information may indicate the availability of UL use at the SN. At least one processor may be configured to send an SN modification message to a first node working as a primary node (MN) via an Xn interface. The indication information for the MN termination split bearer may be used to identify the UL primary path of the MN termination split bearer. The UL primary path may be associated with one of the primary cell group (MCG) of the MN and the secondary cell group (SCG) of the SN.

[0239] According to an embodiment, the MN terminated split bearer may be a data radio bearer (DRB) having both MCG resources related to the MN and SCG resources related to the SN. The indication information may indicate whether the SCG resources are available for AUL transmission in the SN.

[0240] According to an embodiment, at least one processor may be further configured to receive an SN modification request message from a base station operating as a MN via an Xn interface. At least one processor may be further configured to send an SN modification request confirmation message to a base station operating as a MN via an Xn interface. The SN modification request message may include a UL configuration for a MN terminated split bearer. The UL configuration may indicate a configuration device for how to configure a UL PDCP (Packet Data Convergence Protocol) related to a MN terminated split bearer in the SN. The UL configuration may be associated with the indication information. Receipt of the SN modification request message may indicate a change in the UL primary path.

[0241] According to an embodiment, the at least one processor may be further configured to receive an SN modification confirmation message from the base station serving as the MN through an Xn interface.

[0242] According to an embodiment, at least one processor may be further configured to send a bearer context modification request message to a central unit (CU)-user plane (UP) of the SN via an E1 interface. At least one processor may be further configured to receive a bearer context modification response message from the CU-UP of the SN via an E1 interface. The bearer context modification request message may include an UL configuration for a MN terminated split bearer. The UL configuration may indicate that MCG resources are not used for uplink data, only MCG resources are used for uplink data, or both MCG resources and SCG resources are used for uplink data. Each "processor" herein includes a processing circuit.

[0243] According to an example embodiment, a method performed by a first node operating as a master node (MN) in a dual connection includes receiving an SN modification request message from a second node operating as a secondary node (SN) via an Xn interface. The SN modification request message includes indication information for a MN terminated split bearer associated with a packet data convergence protocol (PDCP) entity in the MN and two radio link control (RLC) entities, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN. The method includes identifying a UL primary path of the MN terminated split bearer based on the indication information for the MN terminated split bearer. The method includes sending a radio resource control (RRC) reconfiguration message including PDCP information for indicating the UL primary path to a user equipment (UE). The UL primary path is associated with one of the first RLC entity of the MN and the second RLC entity of the SN. The indication information indicates whether to enable or disable a secondary cell group (SCG) resource of the SN for the UL primary path of the MN terminated split bearer.

[0244] According to an embodiment, the method further includes: based on the change of the UL main path being identified, sending an SN modification request message to the second node working as the SN through the Xn interface. The method further includes receiving an SN modification request confirmation message from the second node working as the SN through the Xn interface. The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for the UL PDCP related to the MN terminated split bearer in the SN. The configuration method includes a method in which the master cell group (MCG) resources of the MN are not used for the UL PDCP. The UL configuration is based on the change of the UL main path.

[0245] According to an example embodiment, a method performed by a second node operating as a secondary node (SN) in a dual connection includes obtaining uplink state information through at least one of a measurement report or a medium access control (MAC) indication from a user equipment (UE). The method includes generating indication information for a MN terminated split bearer associated with a packet data convergence protocol (PDCP) entity in the MN and two radio link control (RLC) entities, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN. The method includes sending an SN modification request message to a first node operating as a primary node (MN) through an Xn interface, the SN modification request message including indication information for the MN terminated split bearer. The indication information for the MN terminated split bearer is used to identify the UL primary path of the MN terminated split bearer. The UL primary path is associated with one of the first RLC entity of the MN and the second RLC entity of the SN. The indication information indicates whether to enable or disable the secondary cell group (SCG) resource of the SN for the UL primary path of the MN terminated split bearer.

[0246] According to an embodiment, the method further includes receiving an SN modification request message from a first node working as a MN through an Xn interface. The method further includes sending an SN modification request confirmation message to a second node working as a MN through an Xn interface. The SN modification request message includes a UL configuration for a MN terminated split bearer. The UL configuration indicates a configuration method for a UL PDCP related to a MN terminated split bearer in the SN. The configuration method includes a method in which a master cell group (MCG) resource of the MN is not used for UL PDCP. The UL configuration is based on a change in the UL primary path.

[0247] According to an example embodiment, a device of a first node working as a master node (MN) in a dual connection includes at least one transceiver and at least one processor coupled to the at least one transceiver. At least one processor is configured to control at least one transceiver to receive an SN modification message from a second node working as a secondary node (SN) through an Xn interface. The SN modification message includes indication information for a MN terminated split bearer associated with a packet data convergence protocol (PDCP) entity in the MN and two radio link control (RLC) entities, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN. At least one processor is configured to identify a UL primary path of the MN terminated split bearer based on the indication information for the MN terminated split bearer. At least one processor is configured to control at least one transceiver to send a radio resource control (RRC) reconfiguration message including PDCP information for indicating the UL primary path to a user equipment (UE). The UL primary path is associated with one of the first RLC entity of the MN and the second RLC entity of the SN. The indication information indicates whether to enable or disable a secondary cell group (SCG) resource of the SN for the UL primary path of the MN terminated split bearer.

[0248] According to an embodiment, at least one processor is further configured to: based on the change of the UL main path being identified, control at least one transceiver to send an SN modification request message to a second node working as an SN through an Xn interface. At least one processor is further configured to control at least one transceiver to receive an SN modification request confirmation message from a second node working as an SN through an Xn interface. The SN modification request message includes a UL configuration for a MN terminated split bearer. The UL configuration indicates a configuration method for a UL PDCP related to a MN terminated split bearer in the SN. The configuration method includes a method in which a master cell group (MCG) resource of the MN is not used for UL PDCP. The UL configuration is based on a change in the UL main path.

[0249] According to an example embodiment, a device of a second node working as a secondary node (SN) in a dual connection includes at least one transceiver and at least one processor coupled to the at least one transceiver. At least one processor is configured to obtain uplink state information through at least one of a measurement report or a medium access control (MAC) indication from a user equipment (UE). At least one processor is configured to generate indication information for a MN terminated split bearer associated with a packet data convergence protocol (PDCP) entity in the MN and two radio link control (RLC) entities, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN. At least one processor is configured to control at least one transceiver to send an SN modification request message to a first node working as a primary node (MN) through an Xn interface, the SN modification request message including indication information for the MN terminated split bearer. The indication information for the MN terminated split bearer is configured to identify the UL primary path of the MN terminated split bearer. The UL primary path is associated with one of the first RLC entity of the MN and the second RLC entity of the SN. The indication information indicates whether to enable or disable the secondary cell group (SCG) resources of the SN for the UL primary path of the MN terminated split bearer.

[0250] According to an embodiment, at least one processor is further configured to control at least one transceiver to receive an SN modification request message from a first node working as a MN through an Xn interface. At least one processor is further configured to control at least one transceiver to send an SN modification request confirmation message to a second node working as a MN through an Xn interface. The SN modification request message includes a UL configuration for a MN terminated split bearer. The UL configuration indicates a configuration method for a UL PDCP related to a MN terminated split bearer in the SN. The configuration method includes a method in which a master cell group (MCG) resource of the MN is not used for UL PDCP. The UL configuration is based on a change in the UL primary path.

[0251] According to an example embodiment, a method performed by a first node operating as a master node (MN), the method comprising receiving an SN modification request message from a second node operating as a secondary node (SN) via an Xn interface. The SN modification request message includes indication information for indicating whether to enable or disable a secondary cell group (SCG) resource of the SN for uplink transmission. The method comprises, in response to the SN modification request message, sending an SN modification confirmation message to the second node via the Xn interface. The method comprises identifying a UL primary path associated with one of a first radio link control (RLC) entity in the MN and a second RLC entity of the SN based on the indication information. The method comprises sending a radio resource control (RRC) reconfiguration message including packet data convergence protocol (PDCP) information for indicating the UL primary path to a user equipment (UE). In the case where the SCG resource of the SN is disabled, the indicated UL primary path is associated with a first RLC entity in the MN.

[0252] According to an embodiment, the indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN. A first node and a second node are configured for a UE in dual connectivity.

[0253] According to an embodiment, the method further includes: based on the change of the UL primary path being identified, sending an SN modification request message to the second node through the Xn interface. The method includes receiving an SN modification request confirmation message from the second node through the Xn interface. The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for how to configure a UL packet data convergence protocol (PDCP) related to the MN terminated split bearer in the SN. The UL configuration is based on the indication information.

[0254] According to an embodiment, the indication information indicates whether the second RLC entity in the SN is used for UL transmission based on at least one measurement report in the SN.

[0255] According to an example embodiment, a method performed by a secondary node (SN) includes generating indication information for indicating whether to enable or disable a secondary cell group (SCG) resource of the SN for uplink transmission. The method includes sending an SN modification request message to a first node operating as a primary node (MN) via an Xn interface. The SN modification request message includes indication information. The method includes receiving an SN modification confirmation message from the first node via the Xn interface in response to the SN modification request message. The indication information is used to identify a UL primary path associated with one of a first radio link control (RLC) entity in the MN and a second RLC entity of the SN. In the case where the SCG resource of the SN is disabled, the identified UL primary path is associated with the first RLC entity in the MN.

[0256] According to an embodiment, the indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN. A first node and a second node are configured for a UE in dual connectivity.

[0257] According to an embodiment, the method further includes receiving an SN modification request message from the first node via an Xn interface. The method further includes sending an SN modification request confirmation message to the first node via an Xn interface. The SN modification request message includes an UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for how to configure a UL Packet Data Convergence Protocol (PDCP) related to the MN terminated split bearer in the SN. The UL configuration is based on a change in the UL primary path.

[0258] According to an embodiment, the indication information indicates whether the second RLC entity in the SN is used for UL transmission based on at least one measurement report received from the SN.

[0259] According to an example embodiment, a device of a first node working as a master node (MN). The device includes at least one transceiver and at least one processor coupled to the at least one transceiver. At least one processor is configured to control at least one transceiver to receive an SN modification requirement message from a second node working as a secondary node (SN) through an Xn interface. The SN modification requirement message includes indication information for indicating whether to enable or disable the secondary cell group (SCG) resource of the SN for uplink transmission. At least one processor is configured to control at least one transceiver to send an SN modification confirmation message to the second node through the Xn interface in response to the SN modification requirement message. At least one processor is configured to identify a UL primary path associated with one of a first radio link control (RLC) entity in the MN and a second RLC entity of the SN based on the indication information. At least one processor is configured to control at least one transceiver to send a radio resource control (RRC) reconfiguration message including packet data convergence protocol (PDCP) information for indicating the UL primary path to a user equipment (UE). In the case where the SCG resource of the SN is disabled, the indicated UL primary path is associated with the first RLC entity in the MN.

[0260] According to an embodiment, the indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN. A first node and a second node are configured for a UE in dual connectivity.

[0261] According to an embodiment, at least one processor is further configured to: based on the change of the UL primary path being identified, control at least one transceiver to send an SN modification request message to the second node through the Xn interface. At least one processor is further configured to control at least one transceiver to receive an SN modification request confirmation message from the second node through the Xn interface. The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for how to configure a UL packet data convergence protocol (PDCP) related to the MN terminated split bearer in the SN. The UL configuration is based on the indication information.

[0262] According to an embodiment, the indication information indicates whether the second RLC entity in the SN is used for UL transmission based on at least one measurement report in the SN.

[0263] According to an example embodiment, a device of a second node working as a secondary node (SN) includes at least one transceiver and at least one processor coupled to the at least one transceiver. At least one processor is configured to generate indication information for indicating whether to enable or disable the secondary cell group (SCG) resources of the SN for uplink transmission. At least one processor is configured to control at least one transceiver to send an SN modification request message to a first node working as a master node (MN) via an Xn interface. The SN modification request message includes indication information. At least one processor is configured to control at least one transceiver to receive an SN modification confirmation message from the first node via the Xn interface in response to the SN modification request message. The indication information is used to identify a UL primary path associated with one of a first radio link control (RLC) entity in the MN and a second RLC entity of the SN. In the case where the SCG resources of the SN are disabled, the identified UL primary path is associated with the first RLC entity in the MN.

[0264] According to an embodiment, the indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN. A first node and a second node are configured for a UE in dual connectivity.

[0265] According to an embodiment, at least one processor is further configured to control at least one transceiver to receive an SN modification request message from the first node via an Xn interface. At least one processor is further configured to control at least one transceiver to send an SN modification request confirmation message to the first node via an Xn interface. The SN modification request message includes a UL configuration for a MN terminated split bearer. The UL configuration indicates a configuration method for how to configure a UL Packet Data Convergence Protocol (PDCP) related to the MN terminated split bearer in the SN. The UL configuration is based on a change in the UL primary path.

[0266] According to an embodiment, the indication information indicates whether the second RLC entity in the SN is used for UL transmission based on at least one measurement report received from the SN.

[0267] In the above embodiments, the split bearer of DRB has been described as an example. However, the technical principle of the exemplary embodiment can also be applied to the split bearer of SRB in the same way, that is, splitting the SRB bearer.

[0268] In the above-mentioned embodiments, NR-NR DC has been described as an example. However, the technical principles of the exemplary embodiments can also be applied to other types of DC (eg, EN-DC, NGEN-DC, and NE-DC) in the same manner.

[0269] MN and SN can exchange information about PCell and PSCell to configure UL basic path and UL split threshold of MN terminated split bearer or SN terminated split bearer. With this mechanism, MN can control UL path configuration for MN terminated split bearer based on cell group information hosted by other nodes. SN can control UL path configuration for SN terminated split bearer based on cell group information hosted by other nodes. "Based on" as used herein covers at least based on.

[0270] Each embodiment herein may be used in conjunction with any other embodiment described herein.

[0271] The example embodiments are capable of identifying an efficient and optimal UL path configuration. According to an embodiment, any network entity constituting a base station may be configured to trigger an operation for changing the UL path of a split bearer. That is, the example embodiments are capable of providing a greater degree of freedom in order to configure the UL primary path and UL split threshold of the split bearer. In addition, the example embodiments are capable of being performed before sending the UL path configuration (e.g., the "primary path" IE of 3GPP TS 38.331) to the UE, thereby providing enhanced compatibility with implementations in existing procedures.

[0272] The methods according to various embodiments described in the claims and / or specification of the present disclosure may be implemented by hardware, software, or a combination of hardware and software.

[0273] When implemented by software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in such a computer-readable storage medium are configured to be run by one or more processors in an electronic device. One or more programs include instructions that cause an electronic device to run the method according to the embodiments described in the claims or specification of the present disclosure.

[0274] Such a program (e.g., software module, software) may be stored in a random access memory, a non-volatile memory including flash memory, a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disk storage device, a compact disk-ROM (CD-ROM), a digital versatile disk (DVD), other types of optical storage devices or magnetic boxes. Alternatively, it may be stored in a memory configured with a combination of some or all of the above. In addition, the corresponding component memories may be provided in multiples. Each "module" herein may include a circuit.

[0275] In addition, the program can be stored in an attachable storage device that can be accessed via a communication network such as, for example, the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a communication network configured with a combination thereof. Such a storage device can access the apparatus for executing the embodiments of the present disclosure through an external port. In addition, a separate storage device on the communication network can be accessed by the apparatus for executing the embodiments of the present disclosure.

[0276] In the above-mentioned specific example embodiments, the components included therein may be expressed in singular or plural form according to the specific embodiment proposed. However, for the convenience of description, such singular or plural expressions may be appropriately selected for the context presented, and the present disclosure is not limited to singular or plural elements. Therefore, an element expressed in plural form may be formed by a singular element, or an element expressed in a singular form may be formed by a plural element.

[0277] While specific embodiments have been described in the detailed description of the present disclosure, it goes without saying that various modifications are possible without departing from the scope of the present disclosure.

[0278] Although the present disclosure has been illustrated and described with reference to various embodiments, it should be understood that the various embodiments are intended to be illustrative rather than restrictive. It will be further understood by those skilled in the art that various changes in form and detail may be made without departing from the true spirit and full scope of the present disclosure including the appended claims and their equivalents. It should also be understood that any of the (one or more) embodiments described herein may be used in conjunction with any other (one or more) embodiments described herein.

Claims

1. A method performed by a first node working as a master node MN in dual connectivity, the method comprising: receiving an SN modification request message from a second node operating as a secondary node SN via an Xn interface, wherein the SN modification request message includes indication information for a MN terminated split bearer associated with a Packet Data Convergence Protocol PDCP entity and two Radio Link Control RLC entities in the MN, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN; identifying a UL primary path of the MN terminated split bearer based on the indication information for the MN terminated split bearer; as well as sending a radio resource control (RRC) reconfiguration message including PDCP information indicating the UL primary path to a user equipment (UE); and The indication information indicates whether to enable or disable the secondary cell group SCG resources of the SN for the UL main path of the MN terminated split bearer.

2. The method according to claim 1, in, The MN terminated split bearer is a data radio bearer DRB including MCG resources associated with the MN and SCG resources associated with the SN, and The indication information indicates whether the SCG resources can be used for uplink transmission in the SN.

3. The method according to claim 1, further comprising: Based on the change of the UL primary path being identified, sending an SN modification request message to the second node working as the SN through the Xn interface; as well as receiving an SN modification request confirmation message from the second node operating as the SN through the Xn interface, The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for the UL PDCP related to the MN terminated split bearer in the SN, The configuration method includes a method in which the primary cell group MCG resources of the MN are not used for the UL PDCP, and The UL configuration is based on a change of the UL main path.

4. The method according to claim 1, further comprising: Based on the fact that the change of the UL primary path is not identified, an SN modification confirmation message is sent to the second node working as the SN through the Xn interface.

5. The method according to claim 1, further comprising: Based on the change of the UL primary path being identified, sending a bearer context modification request message to a central unit CU-user plane UP of the MN through an E1 interface; as well as receiving a bearer context modification response message from the CU-UP of the MN through the E1 interface, The bearer context modification request message includes a UL configuration for the MN terminated split bearer, and Wherein, the UL configuration: Indicates that the MCG resources are not used for uplink data, Indicates that only the MCG resources are used for uplink data, or Indicates that both the MCG resources and the SCG resources are used for uplink data.

6. A method performed by a second node operating as a secondary node SN in dual connectivity, the method comprising: obtaining uplink state information through at least one of a measurement report or a medium access control MAC indication from a user equipment UE; Generate indication information for MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN and two Radio Link Control (RLC) entities, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN; Sending an SN modification request message to a first node working as a master node MN through an Xn interface, wherein the SN modification request message includes the indication information for terminating and splitting the bearer for the MN, The indication information for the MN terminated split bearer is used to identify the UL primary path of the MN terminated split bearer, and wherein the UL primary path is associated with one of the first RLC entity of the MN and the second RLC entity of the SN, and The indication information indicates whether the UL main path of the MN terminated split bearer enables or disables the secondary cell group SCG resources of the SN.

7. The method according to claim 6, in, The MN terminated split bearer is a data radio bearer DRB including MCG resources associated with the MN and SCG resources associated with the SN, and The indication information indicates whether the SCG resources can be used for uplink transmission in the SN.

8. The method according to claim 6, further comprising: receiving an SN modification request message from the first node operating as the MN through an Xn interface; as well as Sending an SN modification request confirmation message to the second node working as the MN through the Xn interface, The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for the UL PDCP related to the MN terminated split bearer in the SN, The configuration method includes a method in which the primary cell group MCG resources of the MN are not used for the UL PDCP, and The UL configuration is based on a change of the UL main path.

9. The method according to claim 6, further comprising: An SN modification confirmation message is received from the first node operating as the MN through the Xn interface.

10. The method according to claim 6, further comprising: Sending a bearer context modification request message to the central unit CU-user plane UP of the SN via the E1 interface; as well as receiving a bearer context modification response message from the CU-UP of the SN through the E1 interface, The bearer context modification request message includes a UL configuration for the MN terminated split bearer, and Wherein, the UL configuration: Indicates that the MCG resources are not used for uplink data, Indicates that only the MCG resources are used for uplink data, or Indicates that both the MCG resources and the SCG resources are used for uplink data.

11. A device for a first node working as a master node MN in dual connectivity, the device comprising: at least one transceiver; as well as at least one processor coupled to the at least one transceiver, Wherein, the at least one processor is configured to: Controlling the at least one transceiver to receive an SN modification message from a second node operating as a secondary node SN via an Xn interface, wherein the SN modification message includes indication information for MN terminated split bearers associated with a Packet Data Convergence Protocol PDCP entity and two Radio Link Control RLC entities in the MN, the two RLC entities including a first RLC entity in the MN and a second RLC entity in the SN; identifying a UL primary path of the MN terminated split bearer based on the indication information for the MN terminated split bearer; and controlling the at least one transceiver to send a radio resource control (RRC) reconfiguration message including PDCP information indicating the UL primary path to a user equipment (UE); and The indication information indicates whether to enable or disable the secondary cell group SCG resources of the SN for the UL main path of the MN terminated split bearer.

12. The device according to claim 11, in, The MN terminated split bearer is a data radio bearer DRB including MCG resources associated with the MN and SCG resources associated with the SN, and The indication information indicates whether the SCG resources can be used for uplink transmission in the SN.

13. The device according to claim 11, wherein: The at least one processor is further configured to: Based on the change of the UL primary path being identified, controlling the at least one transceiver to send an SN modification request message to the second node operating as the SN through the Xn interface; as well as controlling the at least one transceiver to receive an SN modification request confirmation message from the second node operating as the SN through the Xn interface, The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for the UL PDCP related to the MN terminated split bearer in the SN, The configuration method includes a method in which the primary cell group MCG resources of the MN are not used for the UL PDCP, and The UL configuration is based on a change of the UL main path.

14. The device according to claim 11, wherein: The at least one processor is further configured to: based on the fact that the change of the UL primary path is not identified, control the at least one transceiver to send an SN modification confirmation message to the second node operating as the SN through the Xn interface.

15. The device according to claim 11, wherein The at least one processor is further configured to: Based on the change of the UL primary path being identified, controlling the at least one transceiver to send a bearer context modification request message to a central unit CU-user plane UP of the MN through an E1 interface; as well as controlling the at least one transceiver to receive a bearer context modification response message from the CU-UP of the MN through the E1 interface, The bearer context modification request message includes a UL configuration for the MN terminated split bearer, and Wherein, the UL configuration: Indicates that the MCG resources are not used for uplink data, Indicates that only the MCG resources are used for uplink data, or Indicates that both the MCG resources and the SCG resources are used for uplink data.

16. A method performed by a first node operating as a master node MN, the method comprising: receiving an SN modification request message from a second node operating as a secondary node SN via an Xn interface, wherein the SN modification request message includes indication information for indicating whether to enable or disable a secondary cell group SCG resource of the SN for uplink transmission; In response to the SN modification request message, sending an SN modification confirmation message to the second node through the Xn interface; identifying, based on the indication information, a UL primary path associated with one of a first radio link control RLC entity in the MN and a second RLC entity in the SN; as well as Sending a radio resource control RRC reconfiguration message including packet data convergence protocol PDCP information indicating the UL primary path to a user equipment UE, Wherein, when the SCG resources of the SN are disabled, the indicated UL primary path is associated with the first RLC entity in the MN.

17. The method according to claim 16, in, The indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN, and The first node and the second node are configured for the UE in dual connectivity.

18. The method according to claim 17, further comprising: Based on the change of the UL primary path being identified, sending an SN modification request message to the second node through the Xn interface; as well as receiving an SN modification request confirmation message from the second node through the Xn interface, The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for configuring a UL Packet Data Convergence Protocol (PDCP) related to the MN terminated split bearer in the SN, and The UL configuration is based on the indication information.

19. The method according to claim 16, in, The indication information indicates whether the second RLC entity in the SN is used for the UL transmission based on at least one measurement report in the SN.

20. A method performed by a secondary node SN, the method comprising: Generate indication information for indicating whether to enable or disable the secondary cell group SCG resources of the SN for uplink transmission; Sending an SN modification request message to the first node working as the master node MN through the Xn interface, wherein the SN modification request message includes the indication information; as well as In response to the SN modification request message, receiving an SN modification confirmation message from the first node through the Xn interface, The indication information is used to identify a UL primary path associated with one of a first radio link control RLC entity in the MN and a second RLC entity in the SN, and Wherein, when the SCG resources of the SN are disabled, the identified UL primary path is associated with the first RLC entity in the MN.

21. The method according to claim 20, in, The indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN, and The first node and the second node are configured for the UE in dual connectivity.

22. The method according to claim 21, further comprising: receiving an SN modification request message from the first node through the Xn interface; as well as Sending an SN modification request confirmation message to the first node through the Xn interface, The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for configuring a UL Packet Data Convergence Protocol (PDCP) related to the MN terminated split bearer in the SN, and The UL configuration is based on a change of the UL main path.

23. The method according to claim 20, in, The indication information indicates whether the second RLC entity in the SN is used for the UL transmission based on at least one measurement report received from the SN.

24. A device for a first node working as a master node MN, the device comprising: at least one transceiver; as well as at least one processor coupled to the at least one transceiver, wherein the at least one processor is configured to: Controlling the at least one transceiver to receive an SN modification request message from a second node operating as a secondary node SN through an Xn interface, wherein the SN modification request message includes indication information for indicating whether uplink transmission enables or disables secondary cell group SCG resources of the SN; In response to the SN modification request message, controlling the at least one transceiver to send an SN modification confirmation message to the second node through the Xn interface; identifying, based on the indication information, a UL primary path associated with one of a first radio link control RLC entity in the MN and a second RLC entity in the SN; and controlling the at least one transceiver to send a radio resource control RRC reconfiguration message including packet data convergence protocol PDCP information indicating the UL primary path to a user equipment UE, Wherein, when the SCG resources of the SN are disabled, the indicated UL primary path is associated with the first RLC entity in the MN.

25. The device according to claim 24, in, The indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN, and The first node and the second node are configured for the UE in dual connectivity.

26. The apparatus of claim 25, wherein the at least one processor is further configured to: Based on the change of the UL primary path being identified, controlling the at least one transceiver to send an SN modification request message to the second node through the Xn interface; and controlling the at least one transceiver to receive an SN modification request confirmation message from the second node through the Xn interface, in, The SN modification request message includes a UL configuration for the MN terminated split bearer, The UL configuration indicates a configuration method for configuring a UL Packet Data Convergence Protocol (PDCP) related to the MN terminated split bearer in the SN, and The UL configuration is based on the indication information.

27. The device according to claim 24, in, The indication information indicates whether the second RLC entity in the SN is used for the UL transmission based on at least one measurement report in the SN.

28. A device for a second node working as a secondary node SN, the device comprising: at least one transceiver; as well as at least one processor coupled to the at least one transceiver, Wherein, the at least one processor is configured to: Generate indication information for indicating whether to enable or disable the secondary cell group SCG resources of the SN for uplink transmission; controlling the at least one transceiver to send an SN modification request message to the first node working as the master node MN through the Xn interface, wherein the SN modification request message includes the indication information; and In response to the SN modification request message, controlling the at least one transceiver to receive an SN modification confirmation message from the first node through the Xn interface, The indication information is used to identify a UL primary path associated with one of a first radio link control RLC entity in the MN and a second RLC entity in the SN, and Wherein, when the SCG resources of the SN are disabled, the identified UL primary path is associated with the first RLC entity in the MN.

29. The device according to claim 28, in, The indication information is associated with a MN terminated split bearer associated with a Packet Data Convergence Protocol (PDCP) entity in the MN, and The first node and the second node are configured for the UE in dual connectivity.

30. The device according to claim 29, wherein: The at least one processor is further configured to: controlling the at least one transceiver to receive an SN modification request message from the first node through the Xn interface; and controlling the at least one transceiver to send an SN modification request confirmation message to the first node through the Xn interface, The SN modification request message includes a UL configuration for the MN terminated split bearer. The UL configuration indicates a configuration method for configuring a UL Packet Data Convergence Protocol (PDCP) related to the MN terminated split bearer in the SN, and The UL configuration is based on a change of the UL main path.

31. The device according to claim 28, in, The indication information indicates whether the second RLC entity in the SN is used for the UL transmission based on at least one measurement report received from the SN.

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