Apparatus and method for supporting data forwarding in wireless communication system

Abstract

An object of the present disclosure is to support data forwarding in a wireless communication system, and a method performed by a first network node may comprise the steps of: transmitting a secondary node (SN) addition request message to a second network node; and receiving an SN addition request acknowledgement message from the second network node.

Description

TECHNICAL FIELD

[0001] The following description relates to a wireless communication system, and more particularly, to an apparatus and method for supporting data forwarding for a subsequent conditional primary secondary cell (PSCell) addition or change (CPAC) procedure in a wireless communication system. BACKGROUND

[0002] Wireless access systems are widely deployed to provide various types of communication services such as voice and data. Generally, a wireless access system is a multiple access system that can support communication by shared use of a resource (for example, a bandwidth, transmit power, and the like). Examples of multiple access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and the like.

[0003] In particular, since many communication devices require large communication capacity, an enhanced mobile broadband (eMBB) communication technology that improves compared to an existing radio access technology (RAT) has been proposed. In addition, a communication system that not only considers massive machine type communications (mMTC) that connects multiple devices and objects to provide various services anytime and anywhere but also considers reliability and latency sensitive services / user equipments (UEs) has been proposed. Various technical configurations for this purpose are being proposed. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] The disclosure relates to an apparatus and method for efficiently supporting data forwarding in a wireless communication system.

[0006] The disclosure relates to an apparatus and method for supporting data forwarding for a subsequent conditional primary secondary cell (PSCell) addition or change (CPAC) procedure in a wireless communication system.

[0007] The disclosure relates to an apparatus and method for supporting a subsequent CPAC without reconfiguration or reinitialization of a CPAC configuration in a wireless communication system.

[0008] The disclosure relates to an apparatus and method for obtaining information related to a data forwarding proposal from at least one candidate secondary node (SN) during a PSCell addition or change preparation phase in a wireless communication system.

[0009] The disclosure relates to an apparatus and method for obtaining information related to a data forwarding proposal of a candidate SN using an SN addition procedure in a wireless communication system.

[0010] The disclosure relates to a device and method for retrieving information related to a data forwarding proposal of a candidate SN using an SN addition request message in a wireless communication system.

[0011] The disclosure relates to a device and method for transmitting an SN addition acknowledgement message including information related to a data forwarding proposal in a wireless communication system.

[0012] The disclosure relates to a device and method for obtaining information related to a data forwarding proposal of at least one of a protocol data unit (PDU) session or a data radio bearer (DRB) initiated by a candidate SN for a subsequent CPAC in a wireless communication system.

[0013] The disclosure relates to a device and method for using information related to a data forwarding proposal pre-obtained from a candidate SN based on the candidate SN being selected for access in a wireless communication system.

[0014] The disclosure relates to a device and method for obtaining information related to a forwarding transport network layer address (TNL) allocated based on a data forwarding proposal of a candidate SN in a wireless communication system.

[0015] Technical objects to be achieved by the disclosure are not limited to what has been mentioned above and a person skilled in the art to which the technical configuration of the disclosure applies can consider other technical objects not mentioned above from the embodiments of the disclosure to be described below.

[0016] Technical solutions

[0017] As an example of the disclosure, a method performed by a first network node in a wireless communication system includes the steps of transmitting a secondary node (SN) addition request message to a second network node and receiving an SN addition request acknowledgement message from the second network node. The SN addition request acknowledgement message can include information related to a data forwarding proposal of the second network node.

[0018] As an example of the disclosure, a method performed by a second network node in a wireless communication system includes the steps of receiving a secondary node (SN) addition request message from a first network node and transmitting an SN addition request acknowledgement message to the first network node. The SN addition request acknowledgement message can include information related to a data forwarding proposal of the second network node.

[0019] As an example of the disclosure, a first network node in a wireless communication system includes a transceiver and a processor connected to the transceiver. The processor is configured to control transmitting a secondary node (SN) addition request message to a second network node and receiving an SN addition request acknowledgement message from the second network node. The SN addition request acknowledgement message can include information related to a data forwarding proposal of the second network node.

[0020] As an example of the disclosure, a second network node in a wireless communication system includes a transceiver and a processor connected to the transceiver. The processor is configured to control: receiving a secondary node (SN) addition request message from a first network node, and transmitting an SN addition request acknowledgement message to the first network node. The SN addition request acknowledgement message can include information related to a data forwarding proposal of the second network node.

[0021] As an example of the disclosure, a communication device includes: at least one processor; and at least one computer memory connected to the at least one processor and storing instructions that, based on execution by the at least one processor, perform operations comprising: transmitting a secondary node (SN) addition request message to a second network node, and receiving an SN addition request acknowledgement message from the second network node. The SN addition request acknowledgement message can include information related to a data forwarding proposal of the second network node.

[0022] As an example of the disclosure, a non-transitory computer-readable medium storing at least one instruction includes at least one instruction executable by a processor. The at least one instruction controls a device to: transmit a secondary node (SN) addition request message to a second network node, and receive an SN addition request acknowledgement message from the second network node. The SN addition request acknowledgement message can include information related to a data forwarding proposal of the second network node.

[0023] Advantageous Effects

[0024] The following effects can be achieved based on the embodiments of the disclosure.

[0025] The disclosure can support subsequent conditional PSCell addition or change (CPAC) in a wireless communication system without reconfiguration or reinitialization of a CPAC configuration.

[0026] Effects obtainable from the embodiments of the disclosure are not limited to what has been described above and thus other effects which are not described above can become apparent to those skilled in the art from the following description of the embodiments of the disclosure. That is, the skilled person can also obtain unexpected effects from the embodiments of the disclosure, which effects are brought about by the configurations described in the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0027] The following drawings are provided to assist in the understanding of the disclosure and can be provided together with the detailed description to provide embodiments of the disclosure. However, technical features of the disclosure are not limited to specific drawings, and features disclosed in each drawing can be combined with each other to constitute new embodiments. Reference numerals in each drawing can indicate structural elements.

[0028] Figure 1 Examples of application to the communication system of the present disclosure are illustrated.

[0029] Figure 2 Examples of UE suitable for the present disclosure are illustrated.

[0030] Figure 3 Examples of functional split between NG-RAN and Fifth Generation Core (5GC) suitable for the present disclosure are illustrated.

[0031] Figure 4 Examples of general architecture of a Fifth Generation (5G) system suitable for the present disclosure are illustrated.

[0032] Figure 5a and Figure 5b Examples of inter-MN handover procedure with / without MN initiated SN change procedure are illustrated.

[0033] Figure 6 Examples of successful procedure of S-NG-RAN node addition preparation are illustrated.

[0034] Figure 7 Examples of unsuccessful procedure of S-NG-RAN node addition preparation are illustrated.

[0035] Figure 8a and Figure 8b Examples of data forwarding support procedure for subsequent CPAC according to embodiments of the present disclosure are illustrated.

[0036] Figure 9 Examples of procedure for obtaining information related to data forwarding proposal according to embodiments of the present disclosure are illustrated.

[0037] Figure 10 Examples of procedure for sending information related to data forwarding proposal according to embodiments of the present disclosure are illustrated. DETAILED DESCRIPTION

[0038] The following embodiments are combinations of components and features of the present disclosure in predetermined forms. Each component or feature can be considered selectively applicable to a corresponding embodiment unless otherwise explicitly described. Each component or feature can be implemented without being combined with other components or features. Also, a plurality of embodiments of the present disclosure can be configured by combining some components and / or features. The order of operations described in embodiments of the present disclosure can be changed. Some configurations or features of one embodiment can be included in another embodiment, or can be substituted with corresponding configurations or features of another embodiment.

[0039] In the description of the drawings, processes or steps that can obscure the gist of the disclosure are not described, and processes or steps that can be understood by those skilled in the art are also not described.

[0040] Throughout the specification, when a part is referred to as "including" or "comprising" a component, it means that it can also include other components rather than excluding other components, unless explicitly stated to the contrary. In addition, the terms such as "unit", "device", and "module" described in the specification mean a unit that processes at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software. In addition, "one" or "one", "one", "the", and similar related words can be used in the context of describing the present disclosure (particularly in the context of the appended claims) with the meaning of including both singular and plural, unless otherwise stated herein or clearly contradicted by the context.

[0041] In the present specification, embodiments of the disclosure have been described with respect to a data transmission and reception relationship between a base station and a mobile station. Here, the base station has the meaning of a terminal node of a network that directly communicates with the mobile station. The specific operations described herein as performed by the base station can be performed by an upper node of the base station in some cases.

[0042] That is, various operations for communicating with a mobile station performed in a network composed of a plurality of network nodes including a base station can be performed by the base station or other network nodes other than the base station. At this time, the "base station" can be replaced by terms such as a fixed station, a node B, an eNB (eNode B), a gNB (gNode B), an ng-eNB, an advanced base station (ABS), or an access point.

[0043] In addition, in the embodiments of the disclosure, a terminal can be replaced by terms such as a user equipment (UE), a mobile station (MS), a subscriber station (SS), a mobile subscriber station (MSS), a mobile terminal, or an advanced mobile station (AMS).

[0044] In addition, the transmission end refers to a fixed and / or mobile node that provides a data service or a voice service, and the reception end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in the case of uplink, the mobile station can be the transmission end, and the base station can be the reception end. Similarly, in the case of downlink, the mobile station can be the reception end, and the base station can be the transmission end.

[0045] Embodiments of the disclosure can be supported by standard documents disclosed in at least one of wireless access systems, including IEEE 802.xx systems, a 3rd Generation Partnership Project (3GPP) system, a 3GPP Long Term Evolution (LTE) system, a 3GPP Fifth Generation (5G) New Radio (NR) system, and a 3GPP2 system, specifically, the embodiments of the disclosure can be supported by the 3GPP Technical Specification (TS) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321, and 3GPP TS 38.331 documents.

[0046] In addition, the embodiments of the disclosure can be applied to other wireless access systems and are not limited to the above-described systems. For example, they can be applicable to systems applied after the 3GPP 5G NR system, and are not limited to a certain system.

[0047] That is, obvious steps or parts not described among the embodiments of the disclosure can be described with reference to the above-described documents. In addition, all terms disclosed in this document can be described through the above-described standard documents.

[0048] Hereinafter, preferred embodiments according to the disclosure will be described in detail with reference to the accompanying drawings. The following detailed description is provided to assist in a comprehensive understanding of one exemplary embodiment of the disclosure and are not intended to represent the only embodiment in which the technical configuration of the disclosure can be implemented. Figure 1 The detailed description disclosed herein is intended to describe exemplary embodiments of the disclosure and is not intended to represent the only embodiment in which the technical configuration of the disclosure can be implemented.

[0049] In addition, specific terms used in the embodiments of the disclosure are provided to assist in understanding the disclosure, and the use of such specific terms can be changed to other forms without departing from the technical spirit of the disclosure.

[0050] The following techniques can be applied to various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc.

[0051] For clarity, the following description is based on a 3GPP communication system (e.g., LTE, NR, etc.), but the technical spirit of the present disclosure is not limited thereto. LTE can refer to technologies after Release 8 of 3GPP TS 36.xxx. In particular, LTE technologies after Release 10 of 3GPP TS 36.xxx can be referred to as LTE-A, and LTE technologies after Release 13 of 3GPP TS 36.xxx can be referred to as LTE-A Pro. 3GPP NR can refer to technologies after Release 15 of TS 38.xxx. 3GPP 6G can refer to technologies after Release 17 and / or Release 18 of TS. "xxx" means a detailed number of a standard document. LTE / NR / 6G can be collectively referred to as a 3GPP system.

[0052] As for background technologies, terms, abbreviations, etc. used in the present disclosure, reference can be made to what is described in standard documents disclosed before the present disclosure. For example, reference can be made to 36.xxx and 38.xxx standard documents.

[0053] As for terms, abbreviations, and other background technologies that can be used in the present document, reference can be made to what is described in the following standard documents disclosed before the present document. In particular, as for LTE / Evolved Packet System (EPS)-related terms, abbreviations, and other background technologies, reference can be made to 36.xxx series, 23.xxx series, and 24.xxx series, and as for New Radio (NR) / 5G System (5GS)-related terms, abbreviations, and other background technologies, reference can be made to 38.xxx series, 23.xxx series, and 24.xxx series.

[0054] Hereinafter, the present specification is described based on the terms as defined above.

[0055] Three main areas of requirements for 5G include (1) enhanced mobile broadband (eMBB) area, (2) massive machine type communication (mMTC) area, and (3) ultra-reliable and low latency communications (URLLC) area.

[0056] Some use cases can require multiple areas for optimization, and other use cases can focus on only one key performance indicator (KPI). 5G supports these various use cases in a flexible and reliable manner.

[0057] Communication system suitable for the present disclosure

[0058] Although not limited thereto, various descriptions, functions, procedures, proposals, methods, and / or operation flowcharts of the present disclosure disclosed in the present document can be applied to various fields requiring wireless communication / connection between devices (e.g., 5G).

[0059] Hereinafter, more specific examples are illustrated with reference to the accompanying drawings. In the following drawings / description, the same reference numerals can illustrate the same or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

[0060] Figure 1 Examples applied to a communication system of the disclosure are illustrated.

[0061] Referring to Figure 1 The communication system 100 applied to the disclosure includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (e.g., 5G NR, LTE), and can be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device can include a robot 100a, a vehicle 100b-1 and 100b-2, an extended reality (XR) device 100c, a handheld device 100d, a home appliance 100e, an Internet of Things (IoT) device 100f, and an artificial intelligence (AI) device / server 100g. For example, the vehicle can include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicles 100b-1 and 100b-2 can include unmanned aerial vehicles (UAVs) (e.g., drones). The XR device 100c includes an augmented reality (AR) / virtual reality (VR) / mixed reality (MR) device, and can be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) mounted in a vehicle, a television, a smart phone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a robot, etc. The handheld device 100d can include a smart phone, a smart pad, a wearable device (e.g., a smart watch, smart glasses), a computer (e.g., a laptop, etc.), etc. The home appliance 100e can include a TV, a refrigerator, a washing machine, etc. The IoT device 100f can include a sensor, a smart meter, etc. For example, the base station 120 and the network 130 can also be implemented as a wireless device, and a specific wireless device 120a can operate as a base station / network node for other wireless devices.

[0062] The wireless devices 100a-100f can be connected to the network 130 through the base stations 120. The AI technology can be applied to the wireless devices 100a-100f, and the wireless devices 100a-100f can be connected to the AI server 100g through the network 130. The network 130 can be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network, etc. The wireless devices 100a-100f can communicate with each other through the base stations 120 / network 130, but can also communicate directly (e.g., sidelink communication) without going through the base stations 120 / network 130. For example, the vehicles 100b-1 and 100b-2 can perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). Also, the IoT device 100f (e.g., a sensor) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices 100a-100f.

[0063] Wireless communication / connections 150a, 150b, and 150c can be established between the wireless devices 100a-100f / base stations 120 and between the base stations 120 / 120. Here, the wireless communication / connections can be implemented through various radio access technologies (e.g., 5G NR), such as uplink / downlink communication 150a, sidelink communication 150b (or D2D communication), and inter-base station communication 150c (e.g., relay, integrated access backhaul (IAB)). Through the wireless communication / connections 150a, 150b, and 150c, wireless devices and base stations / wireless devices and base stations can transmit / receive wireless signals to / from each other. For example, the wireless communication / connections 150a, 150b, and 150c can transmit / receive signals through various physical channels. To this end, based on various proposals of the disclosure, at least some of various configuration information setting procedures, various signal processing procedures (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), resource allocation procedures, etc. for wireless signal transmission / reception can be performed.

[0064] Figure 2 Examples applicable to the UE of the disclosure are illustrated.

[0065] Referring to Figure 2 The UE 200 can include a processor 202, a memory 204, a transceiver 206, one or more antennas 208, a power management module 241, a battery 242, a display 243, a keypad 244, a subscriber identity module (SIM) card 245, a speaker 246, and a microphone 247.

[0066] The processor 202 can be configured to implement proposed descriptions, functions, procedures, methods and / or operational flowcharts disclosed herein. The processor 202 can be configured to control one or more other components in the UE 200 to carry out proposed descriptions, functions, procedures, methods and / or operational flowcharts disclosed herein. Radio interface protocol layers can be implemented in the processor 202. The processor 202 can include ASIC, other chip set, logic circuit and / or data processing apparatus. The processor 202 can be an application processor. The processor 202 can include at least one of a DSP, a central processing unit (CPU), a graphics processing unit (GPU) and a modem (modulator and demodulator).

[0067] The memory 204 is operatively coupled with the processor 202 and can store various information to operate the processor 202. The memory 204 can include ROM, RAM, flash memory, memory card, storage medium and / or other storage device. When implemented in software, the techniques described herein can be implemented using a module or a process, for example, procedures, functions, and so on, to perform the techniques described herein. The module can be stored in the memory 204 and executed by the processor 202. The memory 204 can be implemented within the processor 202 or external to the processor 202 in which case it can be communicatively coupled to the processor 202 via various means as is known in the art.

[0068] The transceiver 206 is operatively coupled with the processor 202 and can transmit and / or receive a wireless signal. The transceiver 206 can include a transmitter and a receiver. The transceiver 206 can include a baseband circuitry for processing radio frequency signals. The transceiver 206 can control the one or more antennas 208 to transmit and / or receive a wireless signal.

[0069] The power management module 241 can manage power used by the processor 202 and / or the transceiver 206. The battery 242 can supply power to the power management module 241.

[0070] The display 243 can output results of processing by the processor 202. The keypad 244 can receive input to be used by the processor 202. The keypad 244 can be shown on the display 243.

[0071] The SIM card 245 is an integrated circuit for securely storing an international mobile subscriber identity (IMSI) and related key, and can be used in the identification and authentication of subscribers in mobile telephony devices, such as mobile phones or computers. Also, contact information can be stored in many SIM cards.

[0072] The speaker 246 can output sound-related results processed by the processor 202. The microphone 247 can receive sound-related input for use by the processor 202.

[0073] In implementations of the present specification, the UE can operate as a transmitting device in uplink and as a receiving device in downlink. In implementations of the present specification, the base station can operate as a receiving device in UL and as a transmitting device in DL. In the present specification, the base station can be referred to as a Node B, an eNode B (eNB), a gNB, and can not be limited to a specific form.

[0074] Further, for example, the UE can be implemented in various forms according to a use case / service. The UE can be configured by various components, devices / parts, and / or modules. For example, each UE can include a communication device, a control device, a memory device, and additional components. The communication device can include a communication circuit and a transceiver. For example, the communication circuit can include one or more processors and / or one or more memories. For example, the transceiver can include one or more transceivers and / or one or more antennas. The control device is electrically connected to the communication device, the memory device, and the additional components, and can control the overall operation of each UE. For example, the control device can control the electrical / mechanical operation of each UE based on programs / codes / instructions / information stored in the memory device. The control device can transmit information stored in the memory device to the outside (e.g., other communication devices) via the communication device through a wireless / wired interface, or store information received from the outside (e.g., other communication devices) in the memory device via the communication device through a wireless / wired interface.

[0075] The additional components can be variously configured according to the type of the UE. For example, the additional components can include at least one of a power device / battery, an input / output (I / O) device (e.g., an audio I / O port, a video I / O port), a driving device, and a computing device. Further, the UE can be implemented in the following forms, but is not limited thereto: a robot (e.g., 100a in FIG. 1), a vehicle (e.g., 100b-1 and 100b-2 in FIG. 1), an XR device (e.g., 100c in FIG. 1), a portable device (e.g., 100d in FIG. 1), a home appliance (e.g., 100e in FIG. 1), an IoT device (e.g., 100f in FIG. 1), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate / environment device, an AI server / device (e.g., 100g in FIG. 1), a base station (e.g., 100h in FIG. 1), and the like. Figure 1 Figure 1 Figure 1 Figure 1 Figure 1 Figure 1 Figure 1 Figure 1 ​​​​​​​(120 in the middle) network nodes. The UE can be used in mobile or fixed locations depending on the use case / service.

[0076] All the various components, devices / parts, and / or modules of the UE can be connected to each other via wired interfaces, or at least some can be wirelessly connected via communication devices. Furthermore, each component, device / part, and / or module of the UE may include one or more elements. For example, the control unit may be configured with one or more processor groups. For instance, the control unit may be configured with a group of communication control processors, application processors (APs), electronic control units (ECUs), graphics processing units, and memory control processors. As another example, the memory device may be configured with RAM, dynamic RAM (DRAM), ROM, flash memory, volatile memory, non-volatile memory, and / or combinations thereof.

[0077] 5G system architecture suitable for the present disclosure

[0078] 5G systems are advanced technologies derived from fourth-generation LTE mobile communication technology. They support new radio access technologies (RATs), extended LTE (eLTE) as an extension of LTE, and non-3GPP (e.g., WLAN) access through the evolution or clean state architecture of existing mobile communication networks.

[0079] 5G systems are service-defined, and the interaction between network functions (NFs) within the 5G system architecture can be represented in the following two ways: - Reference point representation: Represents the interaction between NF services within an NF described by a point-to-point reference point (e.g., N11) between two NFs (e.g., AMF and SMF).

[0080] - Service-based representation: Network functions within the control plane (CP) (e.g., AMF) allow other authorized network functions to access their services. This representation may also include point-to-point reference points where necessary.

[0081] The 5G core (5GC) can include various components, including Access and Mobility Management Function (AMF), Session Management Function (SMF), Policy Control Function (PCF), User Plane Function (UPF), Application Function (AF), Unified Data Management (UDM), and Non-3GPP Interoperability Function (N3IWF).

[0082] The UE connects to the data network via a UPF through a Next Generation Radio Access Network (NG-RAN) including a gNB. The UE can receive data services through untrusted non-3GPP access, such as a Wireless Local Area Network (WLAN). To connect non-3GPP access to the core network, an N3IWF can be deployed.

[0083] The N3IWF manages interoperability between non-3GPP access points and 5G systems. When a UE connects to a non-3GPP access point (e.g., WiFi known as IEEE 802.11), the UE can connect to the 5G system via the N3IWF. The N3IWF communicates with the AMF (Advanced Management Function) for control signaling and connects to the UPF (Uplink Function) via the N3 interface for data transmission.

[0084] AMF can manage access and mobility in 5G systems. AMF can perform functions to manage Non-Access Stratum (NAS) security. AMF can perform functions to handle mobility in idle states.

[0085] UPF performs gateway functions for sending and receiving user data. UPF nodes can perform all or part of the user plane functions of a Serving Gateway (S-GW) and Packet Data Network Gateway (P-GW) for fourth-generation mobile communications.

[0086] The UPF serves as the boundary point between the Next Generation RAN (NG-RAN) and the core network, and is an element that maintains the data path between the gNB and the SMF. Furthermore, the UPF acts as a mobility anchor point when the UE moves across an area served by the gNB. The UPF can perform the function of disposing of PDUs. For mobility within the NG-RAN (e.g., NG-RAN defined after 3GPP Release 15), the UPF can route packets. Additionally, the UPF can serve as an anchor point for mobility with other 3GPP networks (e.g., RANs defined before 3GPP Release 15), such as UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network (UTRAN), Evolved UTRAN (E-UTRAN), or GSM (Global System for Mobile Communications) / EDGE (Global Evolution Enhanced Data Rate) Radio Access Network (GERAN). The UPF can correspond to the termination point of the data interface toward the data network.

[0087] PCF is the node that controls operator policies. AF is the server that provides various services to UE. UDM is the server that manages subscriber information, such as the Home Subscriber Server (HSS) in fourth-generation mobile communications. UDM 460 stores and manages subscriber information in the Unified Data Repository (UDR).

[0088] The SMF can perform the function of allocating Internet Protocol (IP) addresses to UEs. Furthermore, the SMF can control Protocol Data Unit (PDU) sessions.

[0089] For ease of description below, reference numerals for AMF, SMF, PCF, UPF, AF, UDM, N3IWF, gNB, or UE may be omitted, and reference may be made to the descriptions in standard documents previously published in this document.

[0090] Figure 3 An example of functional separation between NG-RAN and fifth-generation core (5GC) applicable to this disclosure is illustrated.

[0091] Reference Figure 3 The UE connects to the data network (DN) via the next-generation RAN. Control plane function (CPF) nodes perform all or part of the functions of the mobility management entity (MME) for fourth-generation mobile communications, as well as all or part of the control plane functions of the serving gateway (S-GW) and PDN gateway (P-GW). CPF nodes include the AMF and SMF.

[0092] UPF nodes perform the functions of a gateway through which user data is sent and received.

[0093] The Authentication Server Function (AUSF) authenticates and manages the UE. The Network Slice Selection Function (NSSF) is a node used for network slicing as described below.

[0094] Network Open Function (NEF) provides a mechanism to securely open up 5G core services and functions.

[0095] Figure 3 The reference points shown are as follows: N1 represents the reference point between the UE and AMF. N2 represents the reference point between (R)AN and AMF. N3 represents the reference point between (R)AN and UPF. N4 represents the reference point between SMF and UPF. N5 represents the reference point between PCF and AF. N6 represents the reference point between UPF and DN. N7 represents the reference point between SMF and PCF. N8 represents the reference point between UDM and AMF. N9 represents the reference point between UPFs. N10 represents the reference point between UDM and SMF. N11 represents the reference point between AMF and SMF. N12 represents the reference point between AMF and AUSF. N13 represents the reference point between UDM and AUSF. N14 represents the reference point between AMFs. N15 represents the reference point between PCF and AMF in non-roaming scenarios, and the reference point between AMF and PCF of the visited network in roaming scenarios. N16 represents the reference point between SMFs. N22 represents the reference point between AMF and NSSF. N30 represents the reference point between PCF and NEF. N33 can represent the reference point between AF and NEF, and the above entities and interfaces can be configured with reference to the descriptions in the standard documents previously published in this document. N58 represents the reference point between AMF and NSSAAF. N59 represents the reference point between UDM and NSSAAF. N80 represents the reference point between AMF and NSACF. N81 represents the reference point between SMF and NSACF.

[0096] The radio interface protocol is based on the 3GPP radio access network specification. The radio interface protocol consists of a physical layer, a data link layer, and a network layer horizontally, and is vertically divided into a user plane for data information transmission and a control plane for control signal (signaling) transmission.

[0097] The protocol layer can be divided into L1 (layer-1), L2 (layer-2), and L3 (layer-3) based on the three layers of the Open Systems Interconnection (OSI) reference model, which is widely known in communication systems.

[0098] Each wireless protocol layer is described below. Figure 4 An example of a general architecture applicable to the fifth-generation (5G) system of this disclosure is illustrated.

[0099] Reference Figure 4 The access layer (AS) may include the physical (PHY) layer, the medium access control layer, the radio link control (RLC) layer, the packet data convergence protocol (PDCP) layer, and the radio resource control (RRC) layer, and the operation of each layer can be referenced to the descriptions in the standard documents previously published in this document.

[0100] In the TS 37.340 specification document, the MR-DC process is described as follows:

[0101] 10.7.2 Multiple Radio Dual Connectivity (MR-DC) with 5GC

[0102] Inter-MN handover with or without MN-initiated SN change is used to transfer UE context data from the source MN to the target MN, while the UE context at the SN is maintained or moved to another SN. During the inter-MN handover, the target MN decides whether to maintain or change the SN (or release the SN, as described in Clause 10.8). Only intra-RAT inter-MN handovers with or without SN change are supported (e.g., no transition from NGEN-DC to NR-DC).

[0103] Figure 5a and Figure 5b An example of an inter-MN switching process is shown, which has / does not have an MN-initiated SN change process.

[0104] Note 1: This refers to switching between primary nodes where there are no changes to secondary nodes. Figure 5a and Figure 5b The source SN and target SN shown are the same node.

[0105] 1. The source MN initiates the handover process by launching an Xn handover preparation procedure that includes both MCG configuration and SCG configuration. The source MN includes the source SN, UE XnAP ID, SN ID, and UE context in the source SN in the handover request message.

[0106] Note 2: Before step 1, the source MN can trigger an SN modification process initiated by the MN (to the source SN) to retrieve the current SCG configuration and allow the provision of data forwarding related information.

[0107] 2. If the target MN decides to retain the UE context in the source SN, the target MN sends an SN add request to the SN, which includes the SN UE XnAP ID as a reference to the UE context established by the source MN in the SN. If the target MN decides to change the SN to allow incremental configuration, the target MN sends an SN add request to the target SN, which includes the UE context established by the source MN in the source SN. Otherwise, the target MN may send an SN add request to the target SN that does not include the SN UE XnAP ID or the UE context established by the source MN in the source SN.

[0108] 3. The (target) SN responds with an SN addition request confirmation. The (target) SN may include indications of full or incremental RRC configuration.

[0109] Note 2a0: In a CHO with SCG configuration, the target MN implementation ensures that the CG-Config provided from the (target) SN can be used for all CHO preparations.

[0110] 3a. For SN-terminated bearers using MCG resources, the target MN provides Xn-U DLTNL address information in the Xn-U address indication message.

[0111] 4. The target MN includes an MN RRC reconfiguration message to be sent to the UE to perform the handover in the handover request confirmation message, and may also provide a forwarding address to the source MN. If PDU session splitting is performed on the target side during the handover process, the handover request confirmation message includes more than one data forwarding address corresponding to each node. If the target MN and SN decide to maintain the UE context in the SN in steps 2 and 3, the target MN instructs the source MN to maintain the UE context in the SN.

[0112] 5a / 5b. The source MN sends an SN release request message to the (source) SN, which includes an indication of the reason for MCG mobility. The (source) SN acknowledges the release request. If the source MN receives the indication from the target MN, the source MN instructs the (source) SN to maintain the UE context in the SN. If an indication as maintaining the UE context in the SN is included, the SN maintains the UE context.

[0113] 5c. The source MN sends an XN-U address indication message to the (source) SN to transmit data forwarding information. If the PDU session is split on the target side, more than one data forwarding address can be provided.

[0114] 6. The source MN triggers the UE to perform a handover and apply the new configuration.

[0115] 7 / 8. The UE synchronizes with the target MN and replies with an MN RRC reconfiguration completion message.

[0116] 9. If a bearer requiring SCG radio resources is configured, the UE synchronizes to the (target) SN.

[0117] Note 2a1: The order in which the UE performs random access toward the MN (step 7) and random access toward the SN (step 9) is not defined.

[0118] 10. If the RRC connection reconfiguration process is successful, the target MN will notify the (target) SN of the reconfiguration completion message via the SN.

[0119] 11a. The source SN sends secondary RAT data to the source MN using a report message, and includes the amount of data delivered to and received from the UE via NR / E-UTRA radio, as described in Clause 10.11.2.

[0120] Note 2a2: The order in which the source SN sends secondary RAT data using report messages and performs data forwarding with the MN / target SN is undefined. SNs may send reports when transmissions for the relevant QoS cease.

[0121] 11b. The source MN sends a secondary RAT report message to the AMF to provide information about the NR / E-UTRA resources used.

[0122] 12. For bearers using RLC AM, the source MN sends an SN status transmission message to the target MN, including (if necessary) the SN status received from the source SN. If necessary, the target forwards the SN status to the target SN.

[0123] 13. If applicable, data forwarding is performed from the source side. If the SN is preserved, data forwarding can be omitted for SN-terminated bearers or QoS flows preserved in the SN.

[0124] 14-17. The target MN initiates the path switching process. If the target MN includes multiple DL TEIDs for a PDU session in the path switching request message, then if there is a TEID update in the UPF, the path switching confirmation message should include multiple UL TEIDs for the PDU session's UPF.

[0125] Note 3: If a new UL TEID for the UPF is included for the SN, the target MN performs the MN-initiated SN modification process to provide them to the SN.

[0126] 18. The target MN initiates a UE context release procedure toward the source MN.

[0127] 19. Upon receiving a UE context release message from the source MN, the (source) SN releases the C-plane-related resources associated with the UE context toward the source MN. Any ongoing data forwarding can continue. If a UE context hold indication is included in the SN release request message in step 5, the SN will not release the UE context associated with the target MN.

[0128]

[0129] Figure 6 An example of a successful S-NG-RAN node addition preparation process is provided, and Figure 7 An example of an unsuccessful S-NG-RAN node addition preparation process is illustrated. S-NG-RAN node addition preparation is defined and described in the TS 38.423 specification document as follows.

[0130]

[0131] 8.3.1 Preparation for Adding S-NG-RAN Nodes

[0132] 8.3.1.1 Overview

[0133] The purpose of the S-NG-RAN node add preparation process is to request the S-NG-RAN node to allocate resources for dual-connectivity operation for a specific UE.

[0134] This process uses UE-associated signaling.

[0135] 8.3.1.2 Successful Operation

[0136] The M-NG-RAN node initiates this process by sending an S-NG-RAN node add request message to the S-NG-RAN node.

[0137] When an M-NG-RAN node sends an S-Node Add Request message, it should start timer TXn.

[0138] The allocation of resources based on the values ​​of the allocation and retention priority IE included in the QoS flow level QoS parameter IE for each QoS flow should follow the principles specified in TS 38.413[5] for the PDU session resource setting procedure.

[0139] The S-NG-RAN node shall select an encryption algorithm based on the information in the UE security capability IE and the priority list of the local configuration of the AS encryption algorithm, and apply the key indicated in the S-NG-RAN node security key IE as specified in TS 33.501

[28] .

[0140] If the S-node add request message includes the TSC service feature IE for the QoS flow, then the S-NG-RAN node should behave the same as the NG-RAN node during the PDU session resource setup process, as specified in TS 38.413 [5].

[0141] If the S-node add request message includes additional QoS flow information (IE) for the QoS flow, then the S-NG-RAN node should behave the same as the NG-RAN node during the PDU session resource setup process, as specified in TS 38.413 [5].

[0142] For each GBR QoS flow, if an alternative QoS parameter set IE is included in the GBR QoS flow information IE, the S-NG-RAN node should (if supported) behave the same as the NG-RAN node during the PDU session resource setup process, as specified in TS 38.413 [5].

[0143] For each PDU session, if the network instance IE is included in the list of PDU session resources to be added in the IE containing the PDU session resource settings information - SN termination IE and the public network instance IE does not exist, then the S-NG-RAN node should (if supported) use it when selecting transport network resources as specified in TS 23.501 [7].

[0144] For each GBR QoS flow, if the supplied GBR QoS flow information IE is included in the list of QoS flows to be configured contained in the PDU session resource setting information - SN termination IE, then the S-NG-RAN node can request the M-NG-RAN node to configure the DRB to which the QoS flow is mapped to to have MCG resources.

[0145] For each PDU session, if the non-GBR resource IE provided is included in the list of PDU session resources to be added IE and is set to "true", then the S-NG-RAN node can request the M-NG-RAN node to configure the DRB to be mapped to the non-GBR QoS flow of the PDU session to have MCG resources.

[0146] For each PDU session, if the public network instance IE is included in the list of PDU session resources to be added IE containing the PDU session resource settings information - SN termination IE, then the S-NG-RAN node should (if supported) use it when selecting transport network resources as specified in TS23.501 [7].

[0147] Redundant transmission: - For each PDU session, if the redundant UL NG-U UP TNL information IE at the UPF is included in the PDU session resource setting information - SN termination IE, the S-NG-RAN node shall (if supported) use it as the uplink termination point for the user plane data of that PDU session for redundant transmission, and it shall include the redundant DL NG-U UP TNL information IE at the NG-RAN in the PDU session resource setting response information - SN termination IE as described in TS 23.501 [7].

[0148] - For each PDU session, if the redundant public network instance IE is included in the PDU session resource settings information - SN termination IE, the S-NG-RAN node should (if supported) use it when selecting transport network resources for redundant transport as specified in TS 23.501 [7].

[0149] - For each PDU session in which the redundant QoS flow indicator IE is included in the list of QoS flows to be set contained in the S-Node Add Request message, the S-NG-RAN node should (if supported) store and use it as specified in TS 23.501 [7].

[0150] - For each PDU session, if the redundant PDU session information IE is included in the PDU session resource setting information - SN termination IE in the S-node add request message, then the S-node - RAN node shall (if supported) store the received information in the UE context and set the redundant user plane resources for the relevant PDU session as specified in TS 23.501[7].

[0151] For each PDU session resource successfully set up in the S-Node Add Request message that includes redundant PDU session information (IE), the S-NG-RAN node should (if supported) include the RSN information (IE) used in the PDU session resource setup response information -SN termination (IE) in the S-Node Add Request acknowledgment message. If the PDU session pair ID (IE) is included in the redundant PDU session information (IE), the S-NG-RAN node can store and use it to identify paired PDU sessions.

[0152] If the S-node add request message contains the selected PLMN IE, the S-NG-RAN node can use it for RRM purposes.

[0153] If the S-Node Add Request message contains the expected UE behavior IE, the S-NG-RAN node should (if supported) store this information and can use it to optimize resource allocation.

[0154] If the S-node add request message contains a list of mobility restrictions (IEs), the S-NG-RAN node (if supported) should store that information and use it to select the appropriate SCG.

[0155] If the S-node add request message includes the index / frequency selection priority IE to the RAT, the S-NG-RAN node can use it for RRM purposes.

[0156] If the S-NG-RAN node is a gNB and the S-Node Add Request message contains the PCell ID IE, then the S-NG-RAN node should search for the target NR cell among the NR neighbor cells of the indicated PCell, as specified in TS 37.340 [8].

[0157] If the S-node add request message contains the S-NG-RAN node PDU session aggregated maximum bit rate (IE), the S-NG-RAN node can use it for RRM purposes.

[0158] If the S-Node Add Request message contains MR-DC Resource Coordination Information (IE), the S-NG-RAN node should forward it to the lower layer, and it can use it for resource coordination with the M-NG-RAN node or for coordination with sidelink resources used by the M-NG-RAN node. The S-NG-RAN node should consider the value of the received UL Coordination Information (IE) valid until it receives a new update of the IE from the same UE. The S-NG-RAN node should consider the value of the received DL Coordination Information (IE) valid until it receives a new update of the IE from the same UE.

[0159] If the MR-DC resource coordination information IE contains E-UTRA coordination auxiliary information IE or NR coordination auxiliary information IE, then the S-NG-RAN node should (if supported) use this information to determine further coordination of resource utilization between the S-NG-RAN node and the M-NG-RAN node.

[0160] If the S-Node add request message contains the NE-DC TDM mode IE, the S-NG-RAN node should forward it to the lower layer and use it for a single uplink transmission. The S-NG-RAN node should consider the received NE-DC TDM mode IE value valid until it receives a new update of the IE from the same UE.

[0161] If the S-node add request message contains a QoS flow mapping indication (IE), the S-NG-RAN node may consider mapping only uplink QoS flows or downlink QoS flows to the DRB.

[0162] For each bearer requesting the allocation of a PDCP entity at an S-NG-RAN node: An M-NG-RAN node can propose to apply downlink data forwarding by adding a request message's PDU session resource setting information to the S-node and including a DL forwarding IE within the SN-terminated IE. For each bearer that has been granted permission, the S-NG-RAN node can add a request confirmation message's PDU session resource setting response information to the S-node and include a DL forwarding GTP tunnel endpoint IE within the SN-terminated IE to indicate that it accepts the proposed forwarding of downlink data for that bearer.

[0163] - S-NG-RAN nodes can set response information for each bearer in the PDU session resource -SN termination IE including the UL forwarding GTP tunnel endpoint IE to indicate that it requests data forwarding of uplink packets for that bearer.

[0164] - The M-NG-RAN node should add the PDU session resource setting information for the request message to the S node. - The DRB to QoS flow mapping list IE in the SN termination IE includes the RLC mode IE for each bearer offloaded from the M-NG-RAN node to the S-NG-RAN node, and the RLC mode IE indicates the M-NG-RAN mode used for DRB when hosted at the M-NG-RAN node.

[0165] For each bearer where the PDCP entity is located at an M-NG-RAN node: - The M-NG-RAN node should include the RLC mode IE for each bearer in the list of DRBs to be configured in the PDU session resource settings information - MN termination IE of the S-node add request message, to indicate that the RLC mode has been configured at the M-NG-RAN node, so that the S-NG-RAN node should configure the same RLC mode for the MN termination split bearer.

[0166] M-NG-RAN nodes can also propose applying UL data forwarding when offloading QoS flows that are delivered in order of delivery by adding the request message's PDU session resource setting information - SN termination IE to the S-node, including the UL forwarding proposal IE in the data forwarding and offloading information IE of the source NG-RAN node. S-NG-RAN nodes can also add the request confirmation message's PDU session resource setting response information - SN termination IE to the S-node, including the PDU session-level UL data forwarding UP TNL information IE in the data forwarding information IE of the target NG-RAN node, to indicate acceptance of the proposed forwarding.

[0167] If the IMEISV IE of the mask is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) use it to determine the characteristics of the UE for subsequent processing.

[0168] If the UE radio capability ID IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) store the information in the UE context and use the information as defined in TS 23.501 [7] and TS 23.502

[13] .

[0169] The S-NG-RAN node shall report the results of all requested PDU session resources to the M-NG-RAN node in the request confirmation message added to the S node as follows: - The list of successfully established PDU session resources should be included in the list of PDU session resources that are allowed to be added in the IE.

[0170] - The list of PDU session resources that failed to be established should be included in the list of PDU session resources that are not permitted in the IE.

[0171] When an S-node add request confirmation message is received, the M-NG-RAN node should stop timer TXn. DCprep .

[0172] If the S-node add request confirmation message contains MR-DC resource coordination information (IE), the M-NG-RAN node may use it for resource coordination purposes with the S-NG-RAN node. The M-NG-RAN node should consider the received UL coordination information IE value valid until a new update of the IE for the same UE is received. The M-NG-RAN node should consider the received DL coordination information IE value valid until a new update of the IE for the same UE is received. If the E-UTRA coordination assistance information IE or NR coordination assistance information IE is included in the MR-DC resource coordination information IE, the M-NG-RAN node should (if supported) use this information to determine further coordination of resource utilization between the M-NG-RAN node and the S-NG-RAN node.

[0173] An S-NG-RAN node can include the PDCP SN length IE in the list of DRBs to be established for each bearer in the S-node add request confirmation message to indicate the PDCP SN length for that DRB.

[0174] If the S-NG-RAN node UE XnAP ID IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) store and use that information as defined in TS 37.340 [8].

[0175] If the S-node add request message contains the PDCP SN length IE, the S-NG-RAN node should (if supported) store this information and use it for the low-level configuration of the relevant MN termination bearer.

[0176] If the S-Node Add Request message contains the SN Add Trigger Indicator (IE), the S-NG-RAN node shall include the RRC config Indicator (IE) in the S-Node Add Request Confirmation message to notify the M-NG-RAN node whether the S-NG-RAN node applies full or incremental configuration, as specified in TS 37.340 [8].

[0177] If the S-Node Add Request message contains the S-NG-RAN Node Maximum Integrity Protection Data Rate Uplink IE or the S-NG-RAN Node Maximum Integrity Protection Data Rate Downlink IE, then the S-NG-RAN Node should use the received information when implementing the Maximum Integrity Protection Data Rate for the UE.

[0178] If the security indication IE is included in the PDU session resource setting information - SN termination IE of the S-node add request message, then for the relevant PDU session, during the handover preparation process, the behavior of the S-NG-RAN node should be the same as the behavior specified by the same IE in the list IE for the PDU session resources to be set, and the S-NG-RAN node should include the security result IE in the PDU session resource setting response information - SN termination IE.

[0179] If the security result IE is included in the PDU session resource settings information - SN termination IE of the S-node add request message, the S-NG-RAN node can consider this information when deciding whether to perform user plane integrity protection or encryption for the DRB it establishes for the relevant PDU session, except that the split session indicator IE is included in the PDU session resource settings information - SN termination IE and is set to "split". In this case, it should perform user plane integrity protection or encryption based on the information in the security result IE.

[0180] An S-NG-RAN node may consider this information when deciding whether to perform user plane integrity protection or encryption for the DRB it establishes for the relevant PDU session, except that the split session indicator IE is included in the PDU session resource settings information - SN termination IE and is set to "split". In this case, it should perform user plane integrity protection or encryption based on the information in the security result IE. If the S-NG-RAN node is an ng-eNB, it should reject all PDU sessions for which the integrity protection indicator IE is set to "required", as specified in TS 33.501

[28] . If the S-NG-RAN node or M-NG-RAN node is an ng-eNB, the S-NG-RAN node should behave in accordance with clause 6.10.4 of TS 33.501

[28] for PDU sessions for which the integrity protection indicator IE is set to "preferred".

[0181] If the relevant information is available at the S-NG-RAN node, the S-NG-RAN node can include the location information (IE) at the S node in the S node add request confirmation message.

[0182] If the location information report (IE) at the S-node, set to "pscell", is included in the S-node add request, the S-NG-RAN node should begin providing information about the UE's current location. If the location information IE at the S-node is included in the S-node add request confirmation, the M-NG-RAN node should store the included information so that it can be transmitted to the AMF.

[0183] If the default DRB IE is allowed to be included in the PDU session resource settings information - SN termination IE of the S-node add request message and is set to "true", then the S-NG-RAN node can configure the default DRB for the PDU session.

[0184] If the S-node adds a request confirmation message that includes the DRB ID IE for use, then the M-NG-RAN node (if applicable) should function as specified in TS 37.340 [8].

[0185] If a tracking activation IE has been previously received for the UE, it should be included in the S-Node Add Request message. If the tracking activation IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) initiate the requested tracking function as described in TS 32.422

[23] .

[0186] If tracking IE activation is included in the S-node add request message, it includes the following items:

[0187] - If the MDT activation IE is set to "immediate MDT and tracing", the S-NG-RAN node should (if supported) initiate a requested tracing session and MDT session as described in TS 32.422

[23] .

[0188] - If the MDT activation IE is set to "Only Immediate MDT", the S-NG-RAN node should (if supported) initiate the requested MDT session as described in TS32.422

[23] , and the S-NG-RAN node should ignore the interface IE to be traced and the tracing depth IE.

[0189] If the MDT location information IE is within the MDT configuration IE, the S-NG-RAN node should (if supported) store this information and use it in the requested MDT session.

[0190] - An MDT activation IE set to "immediately only" can be used by an S-NG-RAN node to propagate the MDT configuration, as described in TS 37.320

[43] , if the signaling-based MDT PLMN list IE is included in the MDT configuration IE.

[0191] - If the Bluetooth measurement configuration IE is within the MDT configuration IE, then the S-NG-RAN node should (if supported) use it for the MDT configuration as described in TS 37.320

[43] .

[0192] - If the WLAN measurement configuration IE is within the MDT configuration IE, then the S-NG-RAN node should (if supported) use it for the MDT configuration as described in TS 37.320

[43] .

[0193] - If the sensor measurement configuration IE is within the MDT configuration IE, then the S-NG-RAN node should use it for the MDT configuration as described in TS 37.320

[43] .

[0194] - MDT configuration IE, and if the S-NG-RAN node is a gNB, then at least MDT configuration-NR IE should exist, and if the S-NG-RAN node is an ng-eNB, then at least MDT configuration-EUTRA IE should exist.

[0195] If a request for Fast MCG Recovery IE via SRB3 is included in the S-Node Add Request message if it is set to "True", and the S-NG-RAN node decides to configure Fast MCG Link Recovery via SRB3 as specified in TS 37.340 [8], then the S-NG-RAN node should (if supported) include the available Fast MCG Recovery IE via SRB3 set to "True" in the S-Node Add Request Confirmation message.

[0196] If the QoS Monitoring Request IE is included in the list of DRBs to be set in the PDU Session Resource Settings Information - MN Termination IE, containing the QoS Flow Level QoS Parameter IE of the QoS Flow, then the S-NG-RAN node should (if supported) use it to configure the lower layer for delay measurement and QoS monitoring purposes, as specified in TS 23.501 [7]. If the QoS Monitoring Report Frequency IE is included in the list of DRBs to be set in the PDU Session Resource Settings Information - MN Termination IE, containing the QoS Flow Level QoS Parameter IE of the QoS Flow, then the S-NG-RAN node should (if supported) use it for RAN portion delay reporting.

[0197] For each QoS flow successfully established in an S-NG-RAN node, if the QoS monitoring request IE is included in the QoS flow level QoS parameter IE contained in the PDU session resource setting information - SN termination IE, the S-NG-RAN node shall store this information and shall (if supported) perform delay measurement and QoS monitoring as specified in TS 23.501 [7]. If the QoS monitoring report frequency IE is included in the QoS flow level QoS parameter IE contained in the PDU session resource setting information - SN termination IE, the S-NG-RAN node shall store this information and shall (if supported) use it for RAN portion delay reporting. In the case where such a QoS flow is included in the list IE of DRBs to be set in the PDU session resource setting response information - SN termination IE, the M-NG-RAN node shall (if supported) use it to configure the lower layer for delay measurement and QoS monitoring purposes. If the QoS monitoring report frequency IE is included in the list of DRBs to be set in the PDU session resource setting response information - SN termination IE, then the M-NG-RAN node should (if supported) use it for the RAN portion delay reporting.

[0198] For each DRB configured as an MN-terminated split bearer / SCG bearer, if the QoS mapping information IE is included in the list of permitted DRBs in the PDU session resource setting response information - MN termination IE added by the S-node to request acknowledgment message, the M-NG-RAN node should (if supported) use it to set the DSCP and / or IPv6 flow label fields for downlink IP packets sent from the M-NG-RAN node to the S-NG-RAN node via the GTP tunnel indicated by the UP transport layer information IE.

[0199] If the source NG-RAN node ID IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) use it to determine the availability of the direct data path with the indicated source NG-RAN node, and if a direct data forwarding path is available, include the direct forwarding path availability IE in the S-Node Add Request Confirmation message.

[0200] If, for a given QoS flow, the source DL forwarding IP address IE and the source node DL forwarding IP address IE are included in the data forwarding and offloading information IE from the source NG-RAN node in the PDU session resource settings information - SN termination IE contained in the S-Node Add Request message, then the S-NG-RAN node should (if supported) store this information and use it as part of its ACL function configuration action (if such ACL function is deployed).

[0201] If, for a given QoS flow, the source DL forwarding IP address IE is included in the list of QoS flows mapped to the DRB in the PDU session resource setting response information - SN termination IE contained in the S node add request confirmation message, then the M-NG-RAN node should (if supported) store this information and use it as part of its ACL functionality (if such ACL functionality is deployed) to identify the source TNL address used for data forwarding in the event of subsequent handover preparation.

[0202] If the managed MDT PLMN list IE is included in the S-node add request message, the S-NG-RAN node should (if supported) store the received information in the UE context and use the information to allow subsequent selection of the UE for the managed MDT as defined in TS 32.422

[23] .

[0203] When an S-Node Add Request message is received, the S-NG-RAN node should (if supported) begin collecting SCG information and continue as long as the UE remains in one of its cells.

[0204] If UE history information (IE) from the UE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) store this information.

[0205] If the S-node add request message includes a PSCell change history IE set to "Report Full History", then the S-NG-RAN node should (if supported) signal the latest SCG UE history information to the M-NG-RAN node using the S-NG-RAN node modification procedure initiated by the S-NG-RAN node when each PSCell changes.

[0206] If the IAB node indicates that the IE is included in the S node add request message, then the S-NG-RAN node should (if supported) consider requesting a dual-connection operation for the IAB node. Additionally: - If the No PDU Session Indicator IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) treat the UE as an IAB node without any active PDU sessions, ignore the list IE of PDU session resources to be added, and should not take any action regarding PDU session settings. Subsequently, the M-NG-RAN node should (if supported) ignore the list IE of permitted PDU session resources in the S-Node Add Request Confirmation message.

[0207] - If the F1 Termination IAB-Donor Indicator IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) assume that it will become the F1 Termination IAB-Donor of the IAB node and act as described in TS 38.401 [2].

[0208] If the CHO information SN addition IE is included in the S-Node Addition Request message, the S-NG-RAN node should consider that the S-NG-RAN node addition preparation process has been triggered as part of a conditional handover. It can use the source M-NG-RAN node ID IE and the source M-NG-RAN node UE XnAP ID IE to identify other S-NG-RAN node addition preparation activities associated with that UE. If the estimated arrival probability IE is included in the CHO information SN addition IE included in the S-Node Addition Request message, the S-NG-RAN node can use this information to allocate necessary resources to the UE.

[0209] If the SCG activation request IE is included in the S-Node Add Request message, the S-NG-RAN node can use it to configure the SCG resource as specified in TS 37.340 [8], and should (if supported) include the SCG activation status IE in the S-Node Add Request Confirmation message. If the SCG activation request IE in the S-Node Add Request message is set to "Activate SCG", the S-NG-RAN node should (if supported) activate the SCG resource and set the SCG activation status IE in the S-Node Add Request Confirmation message to "SCG Activated".

[0210] If the Conditional PSCell Add Information Request IE is included in the S-Node Add Request message, the S-NG-RAN node should (if supported) consider the request to involve CPAC, as described in TS 37.340 [8]. Therefore, the S-NG-RAN node should (if supported) include the Conditional PSCell Add Confirmation IE in the S-Node Add Request Confirmation message.

[0211] If the conditional PSCell add information confirmation is included in the S-node add request confirmation message, the M-NG-RAN node should (if supported) treat the indicated PSCell selected by the target SN as a candidate PSCell for CPAC.

[0212] If the CG-CandidateList is included in the S-NG-RAN node to M-NG-RAN node container IE in the S-node add request confirmation message, then the M-NG-RAN node should (if supported) use it for CPAC purposes.

[0213] If the estimated arrival probability IE is included in the conditional PSCell add information request IE included in the S-node add request message, the candidate target S-NG-RAN node can use this information to allocate the necessary resources for the upcoming CPAC process.

[0214] If the maximum bit rate (IE) of the S-NG-RAN node UE slice for a specific S-NSSAI is included in the S-Node Add Request message, the S-NG-RAN node shall (if supported) store the received maximum bit rate of the S-NG-RAN node UE slice and use it for all PDU sessions associated with the S-NSSAI for the relevant UE, as defined in TS 23.501 [7].

[0215] Interaction with the S-NG-RAN node reconfiguration completion process: If an S-NG-RAN node grants at least one PDU session resource, the S-NG-RAN node should start timer TXn when sending an S-Node Add Request acknowledgment message (other than a CPAC request) to an M-NG-RAN node. If TXn DCoverall If the S node is running, the receiving of messages will stop timer TXn once the S node has been reconfigured. DCoverall .

[0216] Interaction with the event notification process

[0217] When an S-Node Add Request message containing the desired activity notification level (IE) is received, the S-NG-RAN node should (if supported) use this information to determine whether to trigger a subsequent activation notification process based on the requested notification level.

[0218] 8.3.1.3 Unsuccessful Operations

[0219] If an S-NG-RAN node cannot accept any bearers or a failure occurs during S-NG-RAN node add preparation, the S-NG-RAN node sends an S-Node Add Request Rejection message with an appropriate reason value to the M-NG-RAN node.

[0220] 8.3.1.4 Abnormal conditions

[0221] If an S-NG-RAN node receives an S-node add request message that does not contain either the PDU session resource setting information -SN terminator or the PDU session resource setting information -MN terminator in the project IE of the PDU session resource to be added, the S-NG-RAN node will be unable to perform the S-NG-RAN node add preparation process, indicating the appropriate reason.

[0222] If the supported encryption algorithms defined in the NR Encryption Algorithm IE in the NR UE Security Capability IE plus the mandatory support for NEA0 in all UEs (TS 33.501

[28] ) do not match any of the algorithms defined in the configuration list of allowed encryption algorithms in the S-NG-RAN node (TS 33.501

[28] ), then the S-NG-RAN node should reject the procedure using an S-Node Add Request Deny message.

[0223] If the supported integrity algorithms defined in the NR Integrity Protection Algorithm IE in the NR UE Security Capability IE do not match any of the algorithms defined in the list of allowed integrity protection algorithms configured in the S-NG-RAN node (TS33.501

[28] ), the S-NG-RAN node shall reject the procedure using an S-Node Add Request Deny Message.

[0224] If an S-NG-RAN node receives an S-Node Add Request message containing an S-NG-RAN UE XnAP ID IE that does not match any existing UE context with such an ID, the S-NG-RAN node should reject the procedure using an S-Node Add Request Reject message.

[0225] If an M-NG-RAN node receives an S-Node Add Request acknowledgment message containing the values ​​of the PDU session ID from the PDU session resource permission list IE and the PDU session resource disallowment list IE, the M-NG-RAN node should treat the setting of the S-NG-RAN node resources for that PDU session as a failure.

[0226] If an S-NG-RAN node receives an S-Node Add Request message for a PDU session that includes PDU session resource settings information -SN termination IE (where the split session indicator IE is included and set to "split", the security result IE is not included, and neither the integrity protection indicator IE nor the confidence protection indicator IE is set to "preferred"), then it should reject the PDU session.

[0227] Interaction with the S-NG-RAN node release process initiated by the M-NG-RAN node: If an M-NG-RAN node receives an S-Node Add Request message that does not contain either the PDU session resource setting response information -SN terminator or the PDU session resource setting response information -MN terminator in the item IE of the permitted PDU session resource, then the M-NG-RAN node should trigger an S-NG-RAN node release procedure initiated by the M-NG-RAN node, indicating an appropriate reason.

[0228] If timer TXn DCprepIf the timeout expires before the M-NG-RAN node receives the S-NG-RAN node add request confirmation message, the M-NG-RAN node should consider the S-NG-RAN node add preparation process to have failed and should trigger the S-NG-RAN node release process initiated by the M-NG-RAN node.

[0229] Interactions with the S-NG-RAN node after reconfiguration and the S-NG-RAN node initiating the S-NG-RAN node release process: If timer TXn DCoverall If the S-NG-RAN node expires before receiving the S-Node Reconfiguration Complete or S-Node Release Request message, the S-NG-RAN node should consider that the requested RRC connection reconfiguration has not been applied by the UE and should trigger the S-NG-RAN node release process initiated by the S-NG-RAN node.

[0230]

[0231] Detailed description of the present disclosure

[0232] This disclosure relates to apparatus and methods for supporting data forwarding between network nodes in a wireless communication system. Specifically, this disclosure relates to apparatus and methods for supporting data forwarding in a wireless communication system for subsequent Conditional Primary / Secondary Cell Addition or Change (CPAC) procedures.

[0233] According to the Rel-18 Network Mobility Enhancement Work Project (WI), the following is obtained to support subsequent CPAC without reconfiguring or reinitializing the CPAC configuration from the network.

[0234]

[0235] 3. Judgment

[0236] When a UE moves from the coverage area of ​​one cell to another, a serving cell change needs to be performed at some point. The current serving cell change is triggered by L3 measurements and completed via a reconfiguration triggered by RRC signaling, which synchronizes changes for PCell and PSCell, and releases / additions for SCells where applicable. All cases involve a full L2 (and L1) reset, resulting in longer latency, greater overhead, and longer downtime compared to beam-switching mobility. The goal of L1 / L2 mobility enhancement is to enable serving cell changes via L1 / L2 signaling to reduce latency, overhead, and downtime.

[0237] In Rel-17 Conditional PSCell Change (CPC) / Conditional PSCell Addition (CPA), a UE configured with CPC / CPA must release the CPC / CPA configuration upon completing random access to the target PSCell. Therefore, the UE has no opportunity to perform subsequent CPC / CPA without prior CPC / CPA reconfiguration and reinitialization from the network. This increases cell change latency and signaling overhead, especially with frequent SCG changes during FR2 operation. Therefore, MR-DC with selective activation of cell groups aims to enable subsequent CPC / CPA after an SCG change without requiring reconfiguration and reinitialization of CPC / CPA preparation from the network. This results in reduced signaling overhead and shorter downtime for SCG changes.

[0238] Currently, CHO and MR-DC cannot be configured simultaneously. This limits the usefulness of both features when MR-DC is configured. If this was not addressed in Rel-17, Rel-18 should specify a mechanism for configuring CHO and MR-DC simultaneously. However, this alone may not be sufficient to optimize MR-DC mobility, as the radio link quality of the conditionally configured PSCell may be insufficient or not the optimal candidate PSCell when the UE accesses the target PCell, potentially impacting UE throughput. To mitigate this throughput impact, Rel-18 CHO+MRDC can consider CHO for CPC / CPA, including the target MCG and multiple candidate SCGs.

[0239] 4. Objectives

[0240] 4.1. Target of SI or core WI or test WI

[0241] The specific objective of this work project is: 1. To specify the mechanisms and processes for L1 / L2-based inter-cell mobility for mobility latency reduction: - Configure and maintain multiple candidate cells to allow for rapid application of configurations for candidate cells [RAN2, RAN3] Dynamic handover mechanisms in candidate serving cells (including SpCell and SCell) based on potential L1 / L2 signaling application scenarios [RAN2, RAN1] L1 enhancements for inter-cell beam management include L1 measurement and reporting, as well as beam indication [RAN1, RAN2]. - Note 1: Early RAN2 involvement is necessary, including further clarifying the possibility of interaction between this project symbol and previous project symbols. - Note 2: Only SSB-based L1 measurements are supported in this version.

[0242] Scheduled advance management [RAN1, RAN2] If needed, CU-DU interface signaling is used to support L1 / L2 mobility [RAN3]. Note 3: FR2-specific enhancements (if any) are not excluded.

[0243] Note 4: The L1 / L2-based inter-cell mobility process is applicable to the following scenarios: - For independent, CA, and NR-DC cases involving changes to the serving cell within a CG, the MCG takes precedence. - Intra-DU and intra-CU DU scenarios (applicable to standalone and CA: no new RAN interfaces expected) - Both within and between frequencies - Both FR1 and FR2 - The source cell and the target cell can be synchronous or asynchronous.

[0244] 2. To specify the mechanism and process of NR-DC, wherein selective activation of cell groups (at least for SCGs) is performed via L3 enhancement: To allow subsequent cell group changes after a CG change without reconfiguration and re-initiation of CPC / CPA [RAN2, RAN3, RAN4] Note 5: A coordinated RRC modeling approach for objectives 1 and 2 can be considered to minimize the workload in RAN2.

[0245] 3. For CHO[RAN3] in NR-DC, which includes both the target MCG and the target SCG: To specify data forwarding optimizations; and To specify (if necessary) a solution to avoid unnecessary signaling exchanges between the source MN and the target SN.

[0246] 4. To specify the CHO [RAN3, RAN2] for CPC / CPA in NR-DC, including the target MCG and candidate SCG. The CHO, including the target MCG and the target SCG, was used as the baseline. 5. To specify the core RRM requirements (if applicable) [RAN4] for the following: Inter-cell mobility based on L1 / L2 Enhanced CHO configuration resolved by this WI 6. To specify RF requirements to cover frequency-based L1 / L2 mobility (if necessary) [RAN4].

[0247] 7. To investigate and specify how to reuse idle / inactive mode measurements reported during and / or after RRC connection setup / recovery in order to improve SCell / SCG setup delay [RAN4, RAN2], including: The availability and validation of idle / inactive mode measurement results to be reported [RAN4]; and Define the corresponding RRM requirements [RAN4]; and If necessary, define the corresponding signaling support [RAN2] based on the RAN4 results.

[0248] Note 6: RAN4 will coordinate with RAN2 as appropriate to begin work.

[0249] Note 7: R4-2220415 is used as a baseline for future work in RAN4.

[0250] Note 8: Apart from the scenarios mentioned above, enhancements to idle / inactive mode measurements and UE behavior in idle / inactive mode are not included.

[0251]

[0252] As mentioned above, the CPAC configuration prepared and configured for the UE on the network side is not used more than once. That is, after CPAC is performed, the CPAC configuration can be reused for subsequent CPAC operations, with the aim of reducing the signaling overhead and downtime of SCG changes in FR2.

[0253] However, simply reusing the CPAC configuration introduces new problems for data forwarding. This is because the secondary node (SN) corresponding to the PSCell selected during the initial CPAC execution at the UE becomes the new serving SN, and this SN is used as the source for data forwarding from at least one other candidate SN. In Rel-17, conditional configuration is used only once. That is, according to Rel-17, conditional configuration is released on both the UE and network sides during CPAC execution. This means that from the network's perspective, when applying early data forwarding, only data forwarding from the serving node to the candidate target node before execution needs to be considered, and when applying later data forwarding, only data forwarding from the selected target node needs to be considered. However, in the subsequent CPAC currently under development in Rel-18, the PSCell selected during CPAC execution can continue to change over time. Therefore, the network not only needs to forward data originating from one SN, but also needs to handle the forwarding of data originating from another SN at the next point in time.

[0254] In this scenario, reusing the same forwarding transport network layer (TNL) address assigned by the MN and / or candidate SN during CPAC preparation may lead to the following problems: (1) Since 4G LTE, the principle of data forwarding between network nodes is as follows: for downlink (DL), the source node proposes data forwarding, and the target node decides whether to accept it. During CPAC preparation, other candidate SNs can allocate forwarding TNLs (e.g., target GPRS Tunneling Protocol-User Plane Tunnel Endpoint Identifier (GTP-UTEID) and / or target IP address) based on the source SN's DL forwarding proposal. After CPAC is performed and one of the candidate SNs other than the source SN becomes the new serving SN, this principle is violated if the new serving SN reuses the same forwarding TNL for subsequent data forwarding operations. This is because those TNLs are not allocated based on the data forwarding proposal of the new serving SN, but based on the data forwarding proposal of the original source SN.

[0255] (2) Early data forwarding operations may be problematic. For example, suppose there are three SNs (e.g., source SN, candidate SN1, and candidate SN2). Here, a data radio bearer (DRB) terminated by the source SN is permitted at candidate SN1 and candidate SN2 without configuration changes, and DRB-level data forwarding is accepted. When CPAC is successfully configured for the UE, the source SN can perform early data forwarding to other candidate SNs for that DRB. If candidate SN1 becomes the new serving SN after CPAC is performed, the new serving SN candidate SN1 can perform early data forwarding to candidate SN2 for that DRB. If the same forwarding TNL allocated to candidate SN2 for that DRB during the CPAC preparation phase is reused for data forwarding operations of the new serving SN candidate SN1, there is a possibility that packets early forwarded from candidate SN1 will arrive at candidate SN2 along with some packets early forwarded from the source SN. Of course, when CPAC is performed and candidate SN1 becomes the new serving SN, early data forwarding from the source SN is stopped. However, packets forwarded early from the source SN before stopping may arrive at candidate SN2 later than the time when candidate SN1 begins early data forwarding for that DRB to candidate SN2. That is, a DL PDCP SDU with an SN assigned by the source SN and a DL PDCP SDU with an SN assigned by candidate SN1 can both arrive at the same forwarding TNL assigned by candidate SN2. In this case, packets delivered from the source SN can be dropped, and packets delivered from the new serving SN, candidate SN1, should not be dropped unless indicated by an early status transmission from candidate SN1. However, candidate SN2 cannot know which packets arriving via the same forwarding TNL were delivered from the source SN and which were delivered from candidate SN1. Candidate SN2 can verify whether a packet was forwarded from the source SN or candidate SN1 by decoding the source IP address of the received forwarded packet and comparing it with the source IP address of a packet received from the source SN. However, in the current data forwarding operation, verifying the source of each delivered packet is not considered at all, which could introduce an increased burden of implementation complexity.

[0256] Therefore, this disclosure proposes a mechanism for performing data forwarding operations between candidate SNs in subsequent CPAC. Specifically, this disclosure proposes a method for perfectly performing early or late data forwarding operations between candidate SNs during subsequent CPAC procedures of the UE.

[0257] Figure 8a and Figure 8b An example of a data forwarding support process for subsequent CPACs according to an embodiment of this disclosure is illustrated. Figure 8a and Figure 8bSuppose UE 810 performs CPAC and the serving SN changes from source-SN (S-SN) 820-2 to candidate-SN (C-SN) 820-3. S-SN 820-2 can be referred to as the previous serving SN, and C-SN 820-3 can be referred to as the new serving SN.

[0258] Reference Figure 8a and Figure 8b In step S801, a subsequent CPAC preparation and UE configuration process initiated by the MN or SN can be executed. The subsequent CPAC preparation and UE configuration process may include an SN addition process and a UE reconfiguration process. Depending on the implementation, the preparation and UE configuration process for the subsequent CPAC can be configured similarly to that of the Rel-17 CPAC.

[0259] The preparation and UE configuration process for subsequent CPACs initiated by the MN may include TS 37.340. Figure 10 Steps 1 to 4b of .5.2-3. For example, the subsequent CPAC preparation and UE configuration process initiated by the MN includes: Step 1, the MN sends an SN Add Request message to at least one candidate SN; Step 2, at least one candidate SN sends an SN Add Request Confirmation message to the MN; Step 2a, the MN provides an Xn-U Address Indication message including Xn-U DL TNL address information to the candidate SNs terminating the SNs using MCG resources; Step 3, the MN sends an RRC Reconfiguration message including a Conditional PSCell Change (CPC) configuration to the UE; Step 4, the UE applies the RRC Reconfiguration message and sends an RRC Reconfiguration Complete message to the MN; and Step 4a, the MN notifies the source SN that CPC has been configured through the Xn-U Address Indication process.

[0260] In steps 1 and 2, the MN requests the candidate SN to allocate resources for the UE to initiate a conditional SN change via the SN addition procedure, and indicates that the request is for the CPAC. Additionally, the MN provides candidate cells recommended by the MN based on the most recent measurements for the candidate SN to select and configure SCG cells, and provides an upper limit on the number of PSCells that the candidate SN can prepare. The candidate SN determines a list of PSCells to be prepared within the list of candidate cells indicated by the MN, and for each prepared PSCell, the candidate SN determines other SCG SCells and includes the NRRRCReconfiguration in the SN addition request confirmation message. The message, along with the prepared PSCell ID, provides the MN with the new corresponding SCG radio resource configuration. If data forwarding is required, the candidate SN provides the MN with the data forwarding address. The candidate SN includes a full or incremental RRC configuration indication. At this point, the candidate SN can accept or reject each candidate cell listed in the measurement results indicated by the MN, but cannot configure alternative candidates.

[0261] In step 3, the RRC reconfiguration message sent to the UE includes CPC configuration, namely, RRCReconfiguration. Message list and associated execution conditions. Each RRCReconfiguration The message includes RRCReconfiguration received from the candidate SN. The message's SCG configuration and possible MCG configuration. The RRC reconfiguration message may also include an updated MCG configuration for necessary conditional measurement configurations.

[0262] In step 4, the UE stores the CPC configuration included in the RRC reconfiguration message and sends an RRC reconfiguration complete message to the MN. If the UE cannot comply with at least some of the configurations included in the RRC reconfiguration message, the UE may execute a reconfiguration failure procedure.

[0263] In step 4a, the source SN can begin the early state transfer process and early data forwarding, and PDCP SDU delivery can occur during the early data forwarding.

[0264] The subsequent CPAC preparation and UE configuration process initiated by the SN may include TS 37.340. Figure 10 Steps 1 to 9b of .5.2-4. For example, the subsequent CPAC preparation and UE configuration process initiated by the SN includes: Step 1, the source SN requests an SN change from the MN; Step 2, the MN sends an SN add request message to at least one candidate SN; Step 3, at least one candidate SN sends an SN add request confirmation message to the MN; Step 3a, the MN provides an Xn-U address indication message including Xn-U DL TNL address information to the candidate SNs for the bearers terminated by the SN using MCG resources; Step 4, the MN sends an SN modification request message to the source SN; Step 5, the source SN sends an SN modification request confirmation message to the MN; Step 6, the MN sends an RRC reconfiguration message including the conditional PSCell change (CPC) configuration to the UE; Step 7, the UE applies the RRC reconfiguration message and sends an RRC reconfiguration complete message to the MN; Step 8, the MN sends an SN change confirmation message to the source SN; Step 9a, the source SN sends a message indicating that an SN modification is needed to the MN; and Step 9b, the MN sends an RRC reconfiguration message to the UE.

[0265] In step 1, the source SN initiates a conditional SN change process by sending a SN change request message to the MN, including a CPC initiation indication. The SN change request message may include the candidate node ID, SCG configuration (supported for incremental configuration), measurement results for cells that are not CPC candidates, and a proposed list of PSCell candidates recommended by the source SN. The proposed list of PSCell candidates may include execution conditions, an upper limit on the number of PSCells that each candidate SN can prepare, and the SCG measurement configuration for the CPC (e.g., the measurement ID to be used for the CPC).

[0266] In steps 2 and 3, the MN requests each candidate SN to allocate resources for the UE through the SN addition procedure, indicating that the request is for the CPAC. At this time, the SN addition request message may include measurement results received from the source SN and the proposed PSCell candidate list. The candidate SN determines the PSCell list to be prepared within the source proposed PSCell list, determines the SCG SCell for each prepared PSCell, and confirms the NR RRCReconfiguration included in the SN addition request confirmation message. The message provides the MN with the new corresponding SCG radio resource configuration. If data forwarding is required, the candidate SN provides the MN with a data forwarding address. In this case, the candidate SN includes a full or incremental RRC configuration indication and a prepared list of PSCell IDs for the MN. The candidate SN can accept or reject each candidate cell proposed by the source SN, but cannot configure alternative candidates.

[0267] In steps 4 and 5, before configuring the UE, the MN can use an SN modification request message to indicate to the source SN the candidate PSCells accepted by each candidate SN. For example, if a candidate SN has not yet accepted all candidate PSCells proposed by the source SN, it can notify the source SN of the candidate PSCell information accepted by the candidate SNs. Upon receiving the SN modification request message, the source SN can provide the MN with updated measurement configurations and / or execution conditions. Steps 4 and 5 can be omitted.

[0268] In step 6, the RRC reconfiguration message sent to the UE includes CPC configuration, namely, RRCReconfiguration. Message list and associated execution conditions. Each RRCReconfiguration The message includes RRCReconfiguration received from the candidate SN. The message's SCG configuration and possible MCG configuration. The RRC reconfiguration message can also include the NR generated at the source SN. Messages and updated MCG configurations for necessary conditional measurement configurations.

[0269] In step 7, the UE stores the CPC configuration included in the RRC reconfiguration message and sends an RRC reconfiguration complete message to the MN. The RRC reconfiguration complete message may include NR RRCReconfigurationComplete. Message. If the UE cannot comply with at least some of the configurations included in the RRC reconfiguration message, the UE can execute the reconfiguration failure procedure. In step 8, the MN can use the SN change confirmation message to send the SN to RRCReconfigurationComplete. The message is sent to the source SN. If steps 4 and 5 are omitted, the SN change confirmation message may include information related to the candidate PSCell accepted by each candidate SN. The MN sends the SN change confirmation message to indicate to the source SN that the CPC is ready, in which case the source SN continues to provide user data to the UE. If early data forwarding is applied, the MN will notify the source SN of the data forwarding addresses received from the candidate SNs, and if applicable, the source SN may begin early data forwarding along with the early state transmission process. PDCP SDU delivery may occur during early data delivery. If multiple candidate SNs are prepared, the MN includes a list of target SN IDs and a list of data delivery addresses for the source SN.

[0270] In steps 9a and 9b, the source SN can send an SN modification request message to the MN to trigger an update of the CPC execution conditions and / or the corresponding SCG measurement configuration for the CPC. In this case, the MN can reconfigure the UE.

[0271] After performing the subsequent CPAC preparation and UE configuration process initiated by the MN or SN as described above, in step S803, UE 810 sends an RRC reconfiguration completion message to MN 820-1. The RRC reconfiguration complete message may include the SN identifier information of the selected candidate PSCell and the SN for the selected candidate PSCell. RRC reconfiguration complete. Message. At this point, a candidate PSCell can be selected based on the execution conditions for CPAC. Specifically, UE 810 can identify multiple candidate PSCells based on the CPAC configuration and check whether the CPAC execution conditions for the multiple candidate PSCells are met. If the execution conditions of any of the multiple candidate PSCells are met, UE 810 can select that candidate PSCell. UE 810 can apply the RRC reconfiguration message corresponding to the selected candidate PSCell and send an RRC reconfiguration completion message to MN 820-1, including the SN RRC reconfiguration completion message corresponding to the selected candidate PSCell and the SN identifier information of the selected candidate PSCell.

[0272] In step S805, UE 810 performs a random access procedure for C-SN1 820-3 to which the selected PSCell belongs. That is, UE 810 can perform synchronization with the selected PSCell.

[0273] In step S807, MN 820-1 confirms, based on the RRC reconfiguration completion message, that CPAC has been performed for the PSCell belonging to C-SN1820-3 of UE 810. At this time, MN 820-1 can recognize that C-SN1820-3 is the new serving SN. For example, MN 820-1 can confirm that C-SN1820-3 has been selected as the new serving SN of UE 810 based on at least one of the SN identification information of the selected candidate PSCell included in the RRC reconfiguration completion message or the SN corresponding to the selected candidate PSCell in the RRC reconfiguration completion message.

[0274] In step S809, MN 820-1 sends a data forwarding information request message to C-SN1 820-3. The data forwarding information request message may include the identification information of the selected PSCell. That is, MN 820-1 may send a message to C-SN1 820-3 requesting information related to the data forwarding proposal, where C-SN1 820-3 is the new service SN to which the selected PSCell belongs.

[0275] In step S811, C-SN1 820-3 sends a data forwarding information response message to MN 820-1. The data forwarding information response message may include information related to a data forwarding proposal for a terminated PDU session and / or DRB (Terminated PDU Session / DRB of C-SN1). Here, the terminated PDU session and / or DRB of C-SN1 includes data radio bearers in C-SN1 where the PDCP is located in the MR-DC. The information related to the data forwarding proposal may include at least one of information related to an uplink forwarding proposal or information related to a downlink forwarding proposal. For example, the information related to the data forwarding proposal may include information about C-SN1 820-3 proposing uplink and / or downlink forwarding to other SNs to prepare for when C-SN1 820-3 will operate as a new serving SN.

[0276] In step S813, MN 820-1 sends a data forwarding request and update permission message to other SNs (e.g., S-SN 820-2 and C-SN2 820-4) based on information related to the data forwarding proposal received from C-SN1 820-3. The data forwarding request and update permission message may include information related to the data forwarding proposal for a PDU session and / or DRB terminated for MN, and / or information related to the data forwarding proposal for a PDU session and / or DRB terminated for C-SN1.

[0277] In step S815, each of S-SN 820-2 and C-SN2 820-4 sends a data forwarding response message to MN 820-1. The data forwarding response message may include information related to a new forwarding TNL allocated based on information related to the data forwarding proposal included in the data forwarding request and update permission message. Specifically, each of S-SN 820-1 and C-SN2 820-3 may determine whether to accept the data forwarding proposal by considering information related to the data forwarding proposal for a PDU session and / or DRB terminating against MN, or information related to the data forwarding proposal for a PDU session and / or DRB terminating against C-SN1. If each of S-SN 820-1 and C-SN2 820-3 accepts the data forwarding, they may allocate a forwarding TNL for the corresponding PDU session and / or DRB and send a data forwarding response message to MN 820-1 including information related to the allocated forwarding TNL. Information related to the forwarding TNL may include at least one of the target GPRS Tunneling Protocol-User Plane Tunnel Endpoint Identifier (GTP-U TEID) or the target IP address. According to the implementation, if MN 820-1 learns in advance during the CPAC preparation phase that the prepared candidate PSCell of the corresponding SN does not allow the corresponding PDU session and / or DRB, that is, C-SN1 820-3 proposes the PDU session and DRB for data forwarding, steps S813 and S815 of that SN can be omitted. If there are PDU sessions or DRBs relocated to MN during the CPAC preparation phase of prepared candidate PSCells of SNs other than C-SN1, and data forwarding for these is proposed by C-SN1, then MN can determine to accept and assign the corresponding forwarding TNL. On the other hand, for a ready candidate PSCell belonging to an SN other than the new serving SN C-SN1, if the PDU session and / or DRB are established at the MN and relocated to that SN during the CPAC preparation phase and the selected PSCell will serve the UE, the MN can generate a corresponding forwarding proposal and request data forwarding from that SN.

[0278] In step S817, MN 820-1 sends an Xn-U address indication message to S-SN 820-2. The Xn-U address indication message can instruct the cessation of early data forwarding and instruct the initiation of later data forwarding to the new serving SN C-SN1 820-3. That is, by sending an Xn-U address indication to S-SN 820-2, if early data forwarding was triggered at S-SN 820-2, MN 820-1 can stop the triggered early data forwarding and deliver information related to the forwarding TNL previously assigned by C-SN1 820-3, causing S-SN 820-2 to begin later data forwarding to C-SN1 820-3, which has been selected as the new serving SN.

[0279] In step S819, MN 820-1 provides the new serving SN C-SN1 820-3 with information related to a new forwarding TNL allocated by MN and / or at least one other SN. For data forwarding of the PDU session and / or DRB associated with the selected PSCell by C-SN1 820-3, MN 820-1 may provide C-SN1 820-3 with information related to a new forwarding TNL allocated by MN and / or at least one other SN (e.g., S-SN 820-2 and C-SN2 820-4). The new forwarding TNL may include forwarding TNLs allocated at S-SN 820-2 and C-SN2 820-4 based on the data forwarding proposal of C-SN1 820-3. At this time, MN 820-1 may deliver the RRC reconfiguration completion message of the SCG received from UE 810 to C-SN1 820-3. Here, the SCG RRC reconfiguration completion message received from UE810 may be the SN RRC reconfiguration completion message included in the RRC reconfiguration completion message received in step S803.

[0280] In step S821, S-SN 820-2 sends an SN status transmission message to MN 820-1. MN 820 then sends an SN status transmission message to the new service SNC-SN1 820-3.

[0281] In step S823, S-SN 820-2 begins late data forwarding. Late data forwarding can proceed from S-SN 820-2 to C-SN1 820-3. For DRBs with PDCP state preservation, after C-SN1 820-3 receives the SN state transmission message from S-SN 820-2, early data delivery from C-SN1 830-3 to candidate PSCells in other SNs can occur toward the forwarding TNL received in step S819. DRBs with PDCP state preservation can include RLC unacknowledged mode (UM) / acknowledged mode (AM) DRBs with early data delivery or RLC AM bearers without early data delivery.

[0282] In reference Figure 8a and Figure 8b In the described implementation, steps S809 to S815 can be performed during the CPAC preparation process. In this case, the SN addition or modification process can be improved so that the MN retrieves the data forwarding proposals for the approved PDU session and / or DRB for each candidate PSCell. At this time, the retrieved forwarding proposals can be used when the corresponding candidate PSCell is selected for subsequent access. Alternatively, the SN addition or modification process can be improved to retrieve information related to at least one forwarding TNL to be used for subsequent CPAC operations when a candidate PSCell in another SN is selected for access.

[0283] According to the implementation, during steps S809 to S815, the MN may request PDU session modifications for candidate PSCells other than the selected PSCell. In this case, the CPAC configuration previously configured for the UE can be appropriately updated and reconfigured for the UE.

[0284] According to the implementation, when steps S809 and S811 are executed after CPAC execution, the SN modification procedure can be used to retrieve the forwarding proposal from the selected PSCell. That is, the MN can use the SN modification procedure during the CPAC preparation process to retrieve the allowed PDU session or DRB for the selected PSCell.

[0285] According to the implementation, when steps S813 and S815 are performed after CPAC execution, the SN modification process can be used and improved to enable the MN to request data forwarding from a candidate SN other than the selected SN and retrieve information related to the new forwarding TNL. If candidate SNs other than the selected SN are excluded from the candidates for subsequent CPAC operations of the UE, then in steps S813 and S815, the MN can use the SN release process to perform the release process of SNs that do not require data forwarding requests.

[0286] According to the implementation method, the delivery of the RRC reconfiguration completion message for the UE SCG of the selected SN can be performed separately from step S819 using the conventional SN reconfiguration completion process.

[0287] As described above, this disclosure presents apparatus and methods for supporting subsequent CPAC operations in a network system. According to embodiments, the network system may include network nodes (e.g., MN and at least one SN) interconnected via an X2 interface or an Xn interface to support the UE in performing subsequent CPAC operations. According to embodiments, a preparation process for the UE's subsequent CPAC can be performed between the MN and at least one SN.

[0288] According to one implementation, the MN can retrieve a data forwarding proposal from a candidate PDU session or DRB approved by the candidate PSCell. The retrieved data forwarding proposal can be used based on the corresponding PSCell being selected for subsequent UE access. According to another implementation, the MN can request data forwarding from a candidate PSCell and provide a data forwarding proposal as well as a data forwarding proposal retrieved from at least one other candidate PSCell. According to yet another implementation, when another candidate PSCell is selected for access by the UE, the MN can retrieve information related to the forwarding TNL from the candidate PSCell for subsequent CPAC.

[0289] According to one implementation, after a candidate PSCell is selected for UE access, the MN can retrieve a data forwarding proposal from the candidate PSCell. According to another implementation, after another candidate PSCell is selected for UE access, the MN can request data forwarding from the candidate PSCell. According to yet another implementation, after another candidate PSCell is selected for UE access, the MN can retrieve information related to forwarding TNL from the candidate PSCell.

[0290] According to the implementation, the MN can request modification of the previous permission result for at least one other candidate PSCell besides the PSCell selected for UE access, and can reconfigure the CPAC configuration previously configured for the UE.

[0291] According to the implementation method, the MN can selectively provide information related to the data forwarding TNL allocated by at least one other candidate PSCell to the candidate PSCell selected by the UE for access. In this case, the data forwarding proposal of the selected PSCell can be considered.

[0292] According to the implementation method, after receiving an SN state transmission message from a previous serving PSCell, the SN of the candidate PSCell selected for UE access can initiate early data forwarding to at least one other candidate PSCell among the candidate SNs applying PDCP state preservation DRB. The DRB applying PDCP state preservation may include an RLC UM / AM DRB that previously applied early data forwarding, or an RLC AM bearer when early data forwarding is not performed at the previous serving PSCell.

[0293] Figure 9 An example of a process for obtaining information related to a data forwarding proposal according to an embodiment of the present disclosure is illustrated. Figure 9 This example illustrates a method performed by a first network node. The first network node may include an MN. For example, the first network node could be... Figure 8a and Figure 8b MN 820-1 as described in the text.

[0294] Reference Figure 9 In step S901, the first network node sends an SN add request message. The first network node may send the SN add request message to at least one second network node during the subsequent CPAC preparation phase. The second network node may be a candidate SN. The first network node may use the SN add request message to request information related to the data forwarding proposal from at least one second network node. The SN add request message may be a message requesting resource allocation for the UE from at least one candidate SN and indicating that the request is for the CPAC.

[0295] In step S903, the first network node receives an SN Add Request Confirmation Message. The first network node can receive an SN Add Request Confirmation Message in response to an SN Add Request Message from at least one second network node. The SN Add Request Confirmation Message may include information related to the data forwarding proposal of the second network node (which is a candidate SN for a subsequent CPAC). For a PDU session and / or DRB terminated by the second network node, the information related to the data forwarding proposal of the second network node may include at least one of information related to uplink forwarding proposals or information related to downlink forwarding proposals. Here, the PDU session and / or DRB terminated by the second network node includes the data radio bearer of the PDCP located at the second network node in the MR-DC. When the PSCell of the second network node is later selected for UE access in a subsequent CPAC, the information related to the data forwarding proposal of the second network node can be used for data forwarding. That is, when the second network node becomes a new serving SN, the information related to the data forwarding proposal of the second network node can be used. For example, if the PSCell of the second network node meets the execution conditions configured for the UE, the PSCell of the second network node can be selected by the UE. At this point, data forwarding can be performed based on information related to the data forwarding proposal of the second network node and information related to the new forwarding TNL of other network nodes allocated based on the information related to the data forwarding proposal.

[0296] According to the implementation method, the first network node can send information related to the data forwarding proposal of the candidate SN to other network nodes (e.g., the source SN and / or other candidate SNs), and obtain information related to a new forwarding TNL allocated based on the information related to the data forwarding proposal of the candidate SN from each of the other network nodes. The operation of obtaining the information related to the new forwarding TNL can be performed during the CPAC preparation phase or after performing the CPAC preparation and UE configuration procedures. The first network node can provide the obtained information related to the new forwarding TNL to a second network node.

[0297] Figure 10 An example of a process for sending information related to a data forwarding proposal according to an embodiment of the present disclosure is illustrated. Figure 10 An example is provided showing a method performed by a second network node. The second network node may include a candidate SN. For example, the second network node could be... Figure 8a and Figure 8b Candidate SN1 820-3 is described in the text.

[0298] Reference Figure 10In step S1001, the second network node receives an SN add request message. The second network node can receive an SN add request message from the first network node for preparing for subsequent CPAC. The first network node can be an MN. The SN add request message may include a message requesting information related to a data forwarding proposal. The SN add request message may be a message requesting resource allocation for the UE from at least one candidate SN and indicating that the request is for CPAC.

[0299] In step S1003, the second network node sends an SN add request confirmation message. The second network node may respond to the SN add request message by sending an SN add request confirmation message to the first network node. The SN add request confirmation message may include information related to the second network node's data forwarding proposal for a subsequent CPAC. For example, the second network node may send an SN add request confirmation message to the first network node including information related to its forwarding proposal, to prepare for the second network node's PSCell to be selected later for UE access in a subsequent CPAC. For PDU sessions and / or DRBs terminated by the second network node, the information related to the data forwarding proposal may include at least one of information related to uplink forwarding proposals or downlink forwarding proposals. When the second network node becomes a new serving SN, the information related to the second network node's data forwarding proposal can be used. For example, if the second network node's PSCell meets the execution conditions configured for the UE, the second network node's PSCell can be selected by the UE. At this time, data forwarding can be performed based on the information related to the second network node's data forwarding proposal and information related to new forwarding TNLs of other network nodes allocated based on the information related to the data forwarding proposal.

[0300] According to the implementation method, the second network node can receive information related to a new forwarding TNL allocated by other network nodes from the first network node. The new forwarding TNL can be allocated based on information related to the data forwarding proposal of the second network node.

[0301] Examples of the methods proposed above can also be included as one of the implementation methods of this disclosure; therefore, it is clear that they can be considered as types of proposed methods. Furthermore, the methods proposed above can be implemented independently, but can also be implemented as a combination (or merging) of some proposed methods. Rules can be defined such that the base station notifies the terminal via predefined signals (e.g., physical layer signals or higher layer signals) of information regarding whether to apply the proposed methods (or information about the rules governing the proposed methods).

[0302] This disclosure may be embodied in other specific forms without departing from the technical concept and essential features described herein. Therefore, the above detailed description should not be construed as limiting in all respects, but rather as illustrative. The scope of this disclosure should be determined by a reasonable interpretation of the appended claims, and all variations within the equivalent scope of this disclosure are included within its scope. Furthermore, claims that are not explicitly referenced in the claims may be combined to form embodiments, or may be included as new claims by subsequent amendments.

[0303] Industrial applicability

[0304] The embodiments disclosed herein can be applied to a variety of wireless access systems. Examples of various wireless access systems include 3GPP or 3GPP2 systems.

[0305] The embodiments disclosed herein can be applied not only to the various wireless access systems described above, but also to all technical fields employing various wireless access systems. Furthermore, the proposed method can also be applied to millimeter-wave and THz communication systems using the ultra-high frequency band.

[0306] Furthermore, the embodiments disclosed herein can also be applied to various applications, such as autonomous vehicles and drones.

Claims

1. A method performed by a first network node in a wireless communication system, the method comprising the following steps: Send a secondary node SN addition request message to the second network node; as well as Receive the SN addition request confirmation message from the second network node. The SN add request confirmation message includes information related to the data forwarding proposal of the second network node.

2. The method according to claim 1, wherein, The information associated with the data forwarding proposal of the second network node includes information proposing data forwarding for at least one of a Protocol Data Unit (PDU) session or a Data Radio Bearer (DRB) that is terminated at the second network node.

3. The method according to claim 1, wherein, Based on the fact that the second network node is selected for access, the information related to the data forwarding proposal of the second network node is used.

4. The method according to claim 1, wherein, The information associated with the data forwarding proposal of the second network node includes at least one of information related to downlink forwarding proposals or information related to uplink forwarding proposals.

5. The method according to claim 1, wherein, The SN add request message is sent for subsequent conditional primary / secondary cell PSCell additions or CPAC changes, and The second network node includes candidate SNs.

6. The method according to claim 1, wherein, The method further includes the following steps: Based on the information related to the data forwarding proposal of the second network node, information related to at least one forwarding transport network layer address (TNL) is obtained; and Send the obtained information related to the at least one forwarding TNL to the second network node, and The at least one forwarding TNL is assigned by the first network node or at least one other network node based on the information related to the data forwarding proposal of the second network node.

7. The method according to claim 6, wherein, The steps of obtaining the information associated with the at least one forwarding TNL include: Send the information related to the data forwarding proposal of the second network node to the at least one other network node; and Receive information related to the forwarding TNL assigned at the at least one other network node.

8. The method according to claim 1, wherein, The SN add request message includes information related to the candidate PSCell.

9. A method performed by a second network node in a wireless communication system, the method comprising the following steps: Receive the secondary node SN add request message from the first network node; as well as Send an SN add request confirmation message to the first network node. The SN add request confirmation message includes information related to the data forwarding proposal of the second network node.

10. The method according to claim 9, wherein, The method further includes the following steps: receiving information related to at least one forwarding transport network layer address (TNL), and The at least one forwarding TNL is assigned by at least one of the first network node or another network node based on the information related to the data forwarding proposal of the second network node.

11. A first network node in a wireless communication system, the first network node comprising: transceiver; as well as The processor is connected to the transceiver. The processor is configured to control: Send a secondary node SN addition request message to the second network node, and Receive the SN addition request confirmation message from the second network node. The SN add request confirmation message includes information related to the data forwarding proposal of the second network node.

12. A second network node in a wireless communication system, the second network node comprising: transceiver; as well as The processor is connected to the transceiver. The processor is configured to control: Receive the secondary node SN addition request message from the first network node, and Send an SN add request confirmation message to the first network node. The SN add request confirmation message includes information related to the data forwarding proposal of the second network node.

13. A communication device, the communication device comprising: At least one processor; At least one computer memory, connected to the at least one processor and storing instructions that perform operations based on execution by the at least one processor, the operations including: Send a secondary node SN addition request message to the second network node; and Receive the SN addition request confirmation message from the second network node. The SN add request confirmation message includes information related to the data forwarding proposal of the second network node.

14. A non-transitory computer-readable medium storing at least one instruction, the non-transitory computer-readable medium comprising: The at least one instruction that can be executed by a processor, Wherein, the at least one instruction control device is: Send a secondary node SN addition request message to the second network node, and Receive the SN addition request confirmation message from the second network node. The SN add request confirmation message includes information related to the data forwarding proposal of the second network node.

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