Method and device for handover of mobile base station

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. According to an embodiment of the present disclosure, provided is a method performed by a source radio access network (RAN) of a wireless communication system. The method comprises the steps of: transmitting, to a source access and mobility management function (AMF), a handover-required message including a protocol data unit (PDU) session identifier (ID); and receiving, from a target AMF through the source AMF, a message including a cause associated with a handover failure. The cause indicates that single-network slice selection assistance information (S-NSSAI) corresponding to the PDU session ID cannot be used in a mobile gNB (gNodeB) with wireless access backhauling (MWAB) node.

Description

Mobile base station handover method and device

[0001] The present disclosure relates to the mobility of a mobile base station in a wireless communication system. More specifically, the present disclosure relates to a method and apparatus for a handover procedure of a mobile base station when the mobile base station moves and a handover occurs in a wireless communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands called millimeter waves (mmWave), such as 28 GHz and 39 GHz ('Above 6 GHz'). In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, implementation in the terahertz (THX) band (e.g., the 3 terahertz band at 95 GHz) is being considered to achieve transmission speeds 50 times faster and ultra-low latency reduced to one-tenth compared to 5G mobile communication technology.

[0003] In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), technologies included beamforming and Massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands; support for various numerologies (such as operating multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources; initial access technologies to support multi-beam transmission and broadband; definition and operation of Band-Width Parts (BWPs); Low Density Parity Check (LDPC) codes for high-volume data transmission; new channel coding methods such as Polar Codes for the reliable transmission of control information; and Layer 2 pre-processing. Standardization has been carried out for network slicing, which provides a dedicated network specialized for specific services.

[0004] Currently, discussions are underway to improve and enhance the performance of the initial 5G mobile communication technology, taking into account the services that the 5G mobile communication technology was intended to support. Additionally, standardization of the physical layer is in progress for technologies such as V2X (Vehicle-to-Everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (New Radio Unlicensed), which aims for system operation in unlicensed bands to comply with various regulatory requirements; NR terminal low power consumption technology (UE Power Saving); Non-Terrestrial Network (NTN), which is direct terminal-satellite communication for securing coverage in areas where communication with the terrestrial network is impossible; and positioning.

[0005] In addition, standardization is underway in the field of wireless interface architecture / protocols for technologies such as the Industrial Internet of Things (IIoT) for supporting new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) which provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) Handover, and 2-step Random Access (2-step RACH for NR) which simplifies random access procedures. Standardization is also underway in the field of system architecture / services for 5G baseline architectures (e.g., Service based Architecture, Service based Interface) for incorporating Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC), which provides services based on the location of the terminal.

[0006] When such 5G mobile communication systems are commercialized, connected devices, which are increasing explosively, will be connected to communication networks. Accordingly, it is expected that there will be a need to enhance the functionality and performance of 5G mobile communication systems and to integrate the operation of connected devices. To this end, new research is planned to be conducted on 5G performance improvement and complexity reduction, support for AI services, support for metaverse services, and drone communication using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] Furthermore, the advancement of these 5G mobile communication systems encompasses multi-antenna transmission technologies such as new waveforms to guarantee coverage in the terahertz band of 6G mobile communication technology, Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas; metamaterial-based lenses and antennas to improve terahertz band signal coverage; high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum); and Reconfigurable Intelligent Surface (RIS) technology; as well as Full Duplex technology for enhancing frequency efficiency and system networks in 6G mobile communication technology; AI-based communication technologies that realize system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions; and the realization of services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could serve as a foundation for the development of next-generation distributed computing technologies.

[0008] As a result of the aforementioned development and advancements in wireless communication systems, it has become possible to provide various services, and thus measures are required to provide these services smoothly.

[0009] Based on the discussion described above, the present disclosure aims to provide a method and apparatus for a handover procedure of a mobile base station when a mobile base station moves and a handover occurs in a wireless communication system.

[0010] The technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0011] According to various embodiments of the present disclosure, a method for processing a control signal in a wireless communication system may include: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

[0012] According to one embodiment of the present disclosure, a method is provided to be performed by a source RAN (radio access network) of a wireless communication system. The method comprises the steps of: transmitting a handover required message to a source AMF (access and mobility management function) that includes a PDU (protocol data unit) session ID (identifier); and receiving a message from a target AMF through the source AMF that includes a cause associated with a failure of the handover. The cause indicates that S-NSSAI (single-network slice selection assistance information) corresponding to the PDU session ID is not available at a MWAB (mobile gNB (gNodeB) with wireless access backhauling) node.

[0013] According to one embodiment of the present disclosure, a method is provided to be performed by a source AMF (access and mobility management function) of a wireless communication system. The method comprises: receiving a handover required message from a source RAN (radio access network) that includes a protocol data unit (PDU) session ID (identifier); selecting a target AMF for the handover; transmitting a UE (user equipment) context request message to the selected target AMF that includes the PDU session ID and S-NSSAI (single-network slice selection assistance information) corresponding to the PDU session ID; receiving a message from the target AMF that includes a cause associated with the failure of the handover, wherein the cause indicates that the S-NSSAI cannot be used by a MWAB (mobile gNB (gNodeB) with wireless access backhauling) node; and transmitting a message containing the cause to the source RAN.

[0014] According to one embodiment of the present disclosure, a method is provided to be performed by a target access and mobility management function (AMF) of a wireless communication system. The method comprises: receiving a user equipment (UE) context request message from a source AMF that has received a handover required message, the message including a protocol data unit (PDU) session ID (identifier) ​​and single-network slice selection assistance information (S-NSSAI) corresponding to the PDU session ID; and transmitting a message through the source AMF to a source radio access network (RAN), the message including a cause associated with a handover failure. The cause indicates that the S-NSSAI cannot be used at a mobile gNB (gNodeB) with wireless access backhauling (MWAB) node.

[0015] According to one embodiment of the present disclosure, a source RAN (radio access network) of a wireless communication system is provided. The source RAN comprises: at least one transceiver; at least one processor connected to communicate with the at least one transceiver; and a memory connected to communicate with the at least one processor and executable to the at least one processor individually or in any combination thereof, wherein the source RAN stores instructions to transmit a handover required message containing a protocol data unit (PDU) session ID (identifier) ​​to a source access and mobility management function (AMF), and to receive a message containing a cause associated with a handover failure from a target AMF through the source AMF. The cause indicates that single-network slice selection assistance information (S-NSSAI) corresponding to the PDU session ID is not available at a mobile gNB (gNodeB) with wireless access backhauling (MWAB) node.

[0016] According to one embodiment of the present disclosure, a source access and mobility management function (AMF) of a wireless communication system is provided. The source AMF comprises: at least one transceiver; at least one processor connected to communicate with the at least one transceiver; and a memory connected to communicate with the at least one processor and executable individually or in any combination on the at least one processor, wherein the source AMF receives a handover required message containing a protocol data unit (PDU) session ID (identifier) ​​from a source radio access network (RAN), selects a target AMF for handover, transmits a user equipment (UE) context request message containing the PDU session ID and single-network slice selection assistance information (S-NSSAI) corresponding to the PDU session ID to the selected target AMF, receives a message containing a cause associated with the failure of the handover from the target AMF, and transmits a message containing the cause to the source RAN. The above cause indicates that the above S-NSSAI cannot be used in the MWAB (mobile gNB (gNodeB) with wireless access backhauling) node.

[0017] According to one embodiment of the present disclosure, a target access and mobility management function (AMF) of a wireless communication system is provided. The target AMF comprises: at least one transceiver; at least one processor connected to communicate with the at least one transceiver; and a memory connected to communicate with the at least one processor and executable individually or in any combination thereof, wherein the target AMF receives a user equipment (UE) context request message from a source AMF that has received a handover required message, the message including a protocol data unit (PDU) session ID (identifier) ​​and single-network slice selection assistance information (S-NSSAI) corresponding to the PDU session ID, and transmits a message including a cause associated with a handover failure to a source radio access network (RAN) through the source AMF. The cause indicates that the S-NSSAI cannot be used at a mobile gNB (gNodeB) with wireless access backhauling (MWAB) node.

[0018] One embodiment of the present invention provides a device and a method capable of effectively providing services in a wireless communication system.

[0019] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0020] FIG. 1 illustrates the structure of a wireless communication system according to various embodiments of the present disclosure.

[0021] FIG. 2 illustrates an embodiment of the deployment of a mobile base station according to the present disclosure.

[0022] FIG. 3 illustrates an embodiment of a mobile base station structure of the present disclosure.

[0023] FIG. 4 illustrates an example of a protocol stack for an N2 Interface.

[0024] FIG. 5 illustrates an example of a protocol stack for an N3 Interface.

[0025] Figure 6 illustrates a handover scenario when the MWAB moves.

[0026] FIG. 7 is a diagram illustrating a terminal handover procedure using an interface between base stations according to the movement of a terminal according to one embodiment of the present disclosure.

[0027] FIG. 8a is a diagram illustrating a terminal handover procedure using an interface between a base station and an AMF according to an embodiment of the present disclosure as the terminal moves.

[0028] FIG. 8b is a diagram illustrating a terminal handover procedure using an interface between a base station and an AMF according to an embodiment of the present disclosure as the terminal moves.

[0029] FIG. 9a is a diagram illustrating a terminal handover procedure using an interface between a base station and an AMF according to an embodiment of the present disclosure as the terminal moves.

[0030] FIG. 9b is a diagram illustrating a terminal handover procedure using an interface between a base station and an AMF according to an embodiment of the present disclosure as the terminal moves.

[0031] FIG. 10 illustrates the configuration of a terminal according to embodiments of the present disclosure.

[0032] FIG. 11 illustrates the configuration of a base station or network entity according to embodiments of the present disclosure.

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. It should be noted that identical components in the attached drawings are indicated by the same reference numerals whenever possible. Furthermore, detailed descriptions of known functions and configurations that may obscure the essence of the present invention will be omitted.

[0034] In describing the embodiments in this specification, technical details that are well known in the technical field to which this disclosure belongs and are not directly related to the present invention are omitted. This is intended to convey the essence of this disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0035] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference number.

[0036] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the disclosure is defined only by the scope of the claims. Throughout the specification, like reference numerals refer to like components.

[0037] Furthermore, in describing the present disclosure, if it is determined that a detailed description of related functions or configurations could unnecessarily obscure the essence of the present disclosure, such detailed description is omitted. Additionally, the terms described below are defined in consideration of their functions within the present disclosure, and these definitions may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0038] Hereinafter, a base station is an entity that performs resource allocation for a terminal and may be at least one of a gNode B (gNB), eNode B (eNB), Node B, BS (Base Station), wireless access unit, base station controller, or a node on a network. A terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. In this disclosure, a downlink (DL) refers to a wireless transmission path of a signal transmitted by a base station to a terminal, and an uplink (UL) refers to a wireless transmission path of a signal transmitted by a terminal to a base station. Additionally, hereinafter, LTE (long-term evolution), LTE-A (LTE-advanced), or 5G (5 th While a generation system may be described as an example, the embodiments of the present disclosure may also be applied to other communication systems having a similar technical background or channel type. For example, 5th generation mobile communication technology (5G, new radio (NR)) developed after LTE-A may be included, and the 5G below may be a concept that includes existing LTE, LTE-A, and other similar services. Furthermore, the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with technical knowledge, without significantly departing from the scope of the present disclosure.

[0039] At this time, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing the means of instruction to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0040] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specified logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order according to their corresponding functions.

[0041] In this case, the term "part" as used in the embodiments refers to a software or hardware component, such as an FPGA or ASIC, and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to operate one or more processors. Thus, as an example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." Furthermore, the components and "parts" may be implemented to operate one or more CPUs within a device or secure multimedia card. In addition, in the embodiments, '~part' may include one or more processors.

[0042] Wireless communication systems are evolving from providing early voice-oriented services to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards like 3GPP’s HSPA (High Speed ​​Packet Access), LTE (or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2’s HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE’s 802.16e.

[0043] As a representative example of a broadband wireless communication system, the LTE system uses the Orthogonal Frequency Division Multiplexing (OFDM) method for the downlink and the Single Carrier Frequency Division Multiple Access (SC-FDMA) method for the uplink. The uplink refers to a wireless link through which a terminal (User Equipment (UE) or Mobile Station (MS)) transmits data or control signals to a base station (eNode B, gNode B, or base station (BS)), and the downlink refers to a wireless link through which a base station transmits data or control signals to a terminal. The aforementioned multiple access method can distinguish the data or control information of each user by allocating and operating time-frequency resources to be sent, including data or control information for each user, so that they do not overlap (i.e., so that orthogonality is established).

[0044] As a future communication system following LTE, that is, a 5G communication system, it must be able to freely reflect the diverse requirements of users and service providers, and therefore, services that satisfy various requirements simultaneously must be supported. Services being considered for the 5G communication system include enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC), and Ultra-Reliable Low Latency Communication (URLLC).

[0045] eMBB aims to provide data transmission speeds that are superior to those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to provide a peak data rate of 20 Gbps in the downlink and 10 Gbps in the uplink from the perspective of a single base station. Furthermore, while providing these peak data rates, the 5G communication system must also provide an increased user-perceived data rate. To satisfy these requirements, it necessitates improvements in various transmission and reception technologies, including enhanced Multi-Input Multi-Output (MIMO) transmission technology. Additionally, while LTE transmits signals using a maximum bandwidth of 20 MHz in the 2 GHz band, the 5G communication system can meet the data transmission speeds required by using a frequency bandwidth wider than 20 MHz in frequency bands of 3–6 GHz or above 6 GHz.

[0046] Simultaneously, Massive Machine Type Communications (mmTC) is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide IoT, mMTC requires support for a large number of terminal connections within a cell, improved terminal coverage, extended battery life, and reduced terminal costs. Since IoT devices are attached to various sensors and equipment to provide communication functions, the system must be able to support a large number of terminals within a cell (e.g., 1,000,000 terminals / km²). Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in dead zones not covered by cells, such as building basements; therefore, they may require wider coverage compared to other services provided by 5G communication systems. Terminals supporting mMTC must consist of low-cost devices, and because it is difficult to frequently replace terminal batteries, a very long battery life of 10 to 15 years may be required.

[0047] Finally, URLLC is a mission-critical cellular-based wireless communication service. Examples include services used for remote control of robots or machinery, industrial automation, unmanned aerial vehicles, remote health care, and emergency alerts. Therefore, the communication provided by URLLC must offer very low latency and very high reliability. For instance, services supporting URLLC must satisfy an air interface latency of less than 0.5 milliseconds and simultaneously require a packet error rate of 10^-5 or less. Consequently, for services supporting URLLC, 5G systems must provide a Transmission Time Interval (TTI) smaller than for other services, and design considerations may be required to allocate wide resources in the frequency band to ensure the reliability of the communication link.

[0048] The three 5G services, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted within a single system. In this case, different transmission and reception techniques and parameters may be used between the services to satisfy the different requirements of each service. Of course, 5G is not limited to the three services mentioned above.

[0049] According to various embodiments of the present disclosure, each of the phrases such as “A and / or B”, “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof. Terms such as “first”, “second”, or “first” or “second” may be used simply to distinguish the corresponding component from other corresponding components and do not limit the corresponding components in any other aspect (e.g., importance or order).

[0050] Hereinafter, the base station is an entity that performs resource allocation for terminals and may be at least one of a Node B, BS (Base Station), eNB (eNode B), gNB (gNode B), a wireless access unit, a base station control unit, or a node on a network. The terminal may include a UE (User Equipment), MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions. Furthermore, the embodiments of the present disclosure may be applied to other communication systems having a technical background or channel type similar to the embodiments of the present disclosure described below. Additionally, the embodiments of the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, provided that they do not deviate significantly from the scope of the present disclosure.

[0051] In the present disclosure, network technology may refer to standard specifications defined by the International Telecommunication Union (ITU) or 3GPP (e.g., TS 23.501, TS 23.502, TS 23.503, etc.), and the components included in the network structure of FIG. 1 may each refer to a physical entity, or to software that performs an individual function, or to hardware combined with software. Reference numerals denoted by Nx, such as N1, N2, N3, ... in the drawings, represent known interfaces between network functions (NFs) in a 5G Core Network (CN), and since a detailed description can be found in standard specifications (e.g., TS 23.501), a detailed description is omitted.

[0052] Terms used in the following description to identify a connected node, terms referring to a network entity (NE) or network function (NF), terms referring to messages, terms referring to an interface between network entities, terms referring to various identification information, etc., are examples provided for the convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0053] For convenience of explanation below, some terms and names defined in the 3GPP (3rd generation partnership project long term evolution) standard may be used. However, the present disclosure is not limited by the above terms and names and may be equally applied to systems conforming to other standards.

[0054] FIG. 1 illustrates the structure of a wireless communication system according to various embodiments of the present disclosure. More specifically, FIG. 1 illustrates an example of the configuration of a 5G system. Referring to FIG. 1, a 5G network may include at least one of the network entities (NE) or network functions (NF) described below.

[0055] According to one embodiment, (R)AN ((radio) access network) is an entity that performs wireless resource allocation of terminals and may include at least one of eNode B, Node B, BS (base station), NG-RAN (next generation radio access network), 5G-AN (5G access network), 5G NR (5G new radio), a radio access unit, a base station control unit, or a node on the network.

[0056] According to one embodiment, the terminal may include a UE (user equipment), NG UE (next generation UE), MS (mobile station), cellular phone, smartphone, computer, IoT (Internet of Things) device, or a multimedia system capable of performing communication functions.

[0057] In addition, although embodiments of the present disclosure are described below using a 5G system as an example, embodiments of the present disclosure may be applied to other communication systems having a similar technical background. Furthermore, embodiments of the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, without significantly departing from the scope of the present disclosure.

[0058] As wireless communication systems evolve from 4G systems to 5G systems, they define a new core network (CN), called the NG Core (next generation core) or 5GC (5G core network). The new core network can virtualize all existing network entities (NE) to create network functions (NF). According to one embodiment of the present disclosure, a network function may refer to a network entity, a network component, or a network resource.

[0059] According to one embodiment of the present disclosure, 5GC may include one or more NFs illustrated in FIG. 1. Of course, it is not limited to the example of FIG. 1, and 5GC may include a greater number of NFs than the NFs illustrated in FIG. 1 or a smaller number of NFs.

[0060] According to one embodiment, the Access and Mobility Management Function (AMF) may be a network function that manages the access and mobility of a terminal (UE). For example, the AMF may perform network functions such as terminal registration, connection, reachability, mobility management, access verification, authentication, and the generation of mobility events.

[0061] According to one embodiment, the Session Management Function (SMF) may be a network function that manages Packet Data Network (PDN) connections provided to a User Terminal (UE). The PDN connection may be referred to as a Protocol Data Unit (PDU) Session. For example, the SMF may perform network functions such as session management functions through the establishment, modification, and release of sessions and the maintenance of tunnels between the User Plane Function (UPF) and the RAN required for these functions, selection and control of the User Plane (UP), control of traffic processing in the UPF, and control of billing data collection.

[0062] According to one embodiment, the Policy Control Function (PCF) may be a network function that applies a mobile carrier's service policy, billing policy, and policy for a PDU Session to a terminal.

[0063] According to one embodiment, Unified Data Management (UDM) may be a network function that stores information about a subscriber. For example, UDM may perform functions such as generating authentication information for 3GPP security, processing user identifiers (User IDs), managing a list of network functions supporting the UE, and managing subscription information.

[0064] According to one embodiment, the Network Exposure Function (NEF) may be a function that provides information about a terminal to a server located outside the 5G network. Additionally, the NEF may provide information necessary for services to the 5G network and store it in the Unified Data Repository (UDR).

[0065] According to one embodiment, a User Plane Function (UPF) may be a function that performs the role of a gateway for delivering user data (e.g., PDU) to a Data Network (DN). More specifically, the UPF may perform the role of processing data so that data transmitted by a terminal can be delivered to an external network or data received from an external network can be delivered to the terminal. As an example, the UPF may perform network functions such as acting as an anchor between Radio Access Technologies (RATs), packet routing and forwarding, packet inspection, application of user plane policies, generation of traffic usage reports, and buffering.

[0066] According to one embodiment, the Network Repository Function (NRF) can perform the function of storing profiles of NFs and discovering NFs.

[0067] According to one embodiment, the Authentication Server Function (AUSF) can perform terminal authentication in a 3GPP access network and a non-3GPP access network.

[0068] According to one embodiment, the Network Slice Selection Function (NSSF) can perform the function of selecting a Network Slice Instance provided to a terminal.

[0069] According to one embodiment, a Network Data Analytics Function (NWDAF) can collect data from multiple NF(s) for the purpose of efficient operation of a 5GC network. According to one embodiment, the collected data can be analyzed using a machine learning (ML) model, and the results of the analysis can be provided back to the NFs to help each NF provide efficient network services.

[0070] According to one embodiment, an Application Function (AF) can communicate with a carrier network so that an external server (application server) can use network services provided by the carrier network. Depending on the deploying entity, the AF may be classified into an internal AF and an external AF. An internal AF deployed by a network operator can communicate directly with NFs within the carrier network. An AF deployed by a third-party service provider may need to pass through an NEF to communicate with NFs within the carrier network.

[0071] According to one embodiment, the DN (Data Network) may be a data network through which a terminal transmits and receives data in order to use the network operator's service or a third party service.

[0072] According to one embodiment, the Network Slice Admission Control Function (NSACF) can limit the number of PDU sessions of registered terminals in each slice and thereby perform a function of managing resources.

[0073] According to one embodiment, the Network Slice-Specific Authentication and Authorization Function (NSSAAF) can create a slice authentication context for a terminal and perform slice-specific authentication and authorization procedures.

[0074] According to one embodiment, the Edge Application Server Discovery Function (EASDF) can create a domain name system (DNS) context for a PDU session and can perform the function of storing UE IP (internet protocol) addresses, DNS message processing rules, etc. in the context.

[0075] According to one embodiment, a Service Communication Proxy (SCP) can perform indirect communication functions such as searching for services and responding to calls.

[0076] According to one embodiment, the terminal may include an IoT device. The IoT device may include a device that does not use battery power or operates with very little power, and such an IoT device may be referred to as an ambient IoT device (or ambient IoT).

[0077] In 3GPP systems, a conceptual link connecting NFs within a 5G system is defined as a reference point. The following is an example of a reference point included in the 5G system architecture depicted in Figure 1.

[0078] - N1: Reference point between UE and AMF

[0079] - N2: Reference point between (R)AN and AMF

[0080] - N3: Reference point between (R)AN and UPF

[0081] - N4: Reference point between SMF and UPF

[0082] - N6: Reference point between UPF and DN

[0083] - N9: Reference point between 2 core UPFs

[0084] In addition, in 3GPP systems, the 5G system architecture may include service-based interfaces such as the following examples.

[0085] - Nnssf: Service-based interface by NSSF

[0086] - Nnssaaf: Service-based interface based on NSSAAF (Network Slice-Specific Authentication and Authorization Function)

[0087] - Nnef: Service-based interface by NEF

[0088] - Nausf: Service-based interface by AUSF

[0089] - Nnrf: Service-based interface by NRF

[0090] - Namf: Service-based interface by AMF

[0091] - Npcf: Service-based interface by PCF

[0092] - Nsmf: Service-based interface by SMF

[0093] - Nupf: Service-based interface by UPF

[0094] - Nudm: Service-based interface by UDM

[0095] - Naf: Service-based interface by AF

[0096] - Nasaf: Service-based interface by AUSF

[0097] - Neasdf: Service-based interface by EASDF (Edge Application Server Discovery Function)

[0098] - Nnwdaf: Service-based interface by NWDAF

[0099] According to various embodiments of the present disclosure, mobile communication operators have proposed a method of providing network services to people inside a means of transportation (e.g., buses, trains, etc.) where multiple people travel together by installing a mobile base station. Since the base station is mobile, network services can be provided to many people by temporarily installing the base station in a place where a large number of people suddenly gather. Furthermore, because the base station moves together with people traveling together, such as on buses and trains, handover does not occur, thereby providing uninterrupted network services.

[0100] The present disclosure proposes a method for handling a handover when the mobile base station described above moves.

[0101] FIG. 2 illustrates an embodiment of the mobile base station deployment of the present disclosure. Specifically, below, an embodiment related to the deployment or placement of a vehicle-mounted relay (VMR) is described using FIG. 2.

[0102] Mobile base stations (Mobile gNB with wireless access backhaul: MWAB) can be installed on mobile means of transportation such as buses or trains. Mobile base stations can provide network services to passengers inside the means of transportation or to people near the means of transportation.

[0103] Mobile base stations can communicate with the core network to communicate with the data network. Since they are mobile base stations, they can use wireless access backhaul for connection to the core network. Wireless access backhaul can use terrestrial network (TN) gNBs, which are ground base stations, or non-terrestrial network (NTN) gNBs, such as satellites.

[0104] FIG. 3 illustrates an embodiment of the mobile base station structure of the present disclosure. Specifically, an embodiment related to the structure of the VMR is described below using FIG. 3.

[0105] A mobile base station can be composed of two components: MWAB-gNB and MWAB-UE. The MWAB-gNB acts as a mobile base station and can provide network services to terminals. The MWAB-gNB and the terminal can utilize the NR Uu interface to enable the MWAB-gNB to provide network services to the terminal. The MWAB-UE can establish a wireless network connection with the BH PLMN (backhaul PLMN), which is the MWAB's HPLMN (home public land mobile network), thereby allowing the mobile base station to transmit and receive data over the data network. The MWAB-UE can register with the MWAB's BH PLMN as a single terminal. After registering with the network, it can create a PDU session to transmit and receive data over the data network. Since this PDU session will later be used by the MWAB-gNB as a wireless access backhaul, it can be named the BH PDU Session (backhaul PDU session).

[0106] The BH PLMN of a mobile base station and the MWAB Broadcasted PLMN, which is the HPLMN of the terminal to which the mobile base station provides network services, may be different. That is, a mobile base station may receive requests to provide network services to its customers from an MWAB Broadcasted PLMN different from its own BH PLMN. For this reason, the mobile base station can transmit and receive data with N2, N3, or OAM from an MWAB Broadcasted PLMN different from its own BH PLMN by using the BH PDU Session generated by the MWAB-UE. Here, transmitting and receiving data with N2, N3, or OAM may mean configuring an N2, N3, or OAM interface and transmitting and receiving data through it.

[0107] MWAB-gNB can establish IP connectivity-based N2 and N3 connections with the AMF and UPF of the MWAB Broadcasted PLMN, respectively, using the BH PDU Session generated by MWAB-UE. Additionally, it can establish an IP connectivity-based Xn interface with the gNB of the MWAB Broadcasted PLMN or another mobile base station (e.g., MWAB, IAB-node, MBSR, etc.).

[0108] Below, an embodiment associated with the VMR Protocol Stack is described using FIGS. 4 and FIGS. 5.

[0109] FIG. 4 illustrates an example of a Protocol Stack for an N2 Interface.

[0110] MWAB-gNB can establish an N2 connection using the AMF of the MWAB Broadcasted PLMN and the IP / SCTP (or SCTP / IP) based NG-AP protocol using the PDU Session generated by MWAB-UE. This is merely one example and does not limit the use of other protocols.

[0111] FIG. 5 illustrates an example of a Protocol Stack for an N3 Interface.

[0112] MWAB-gNB can establish an N3 connection using the UPF of the MWAB Broadcasted PLMN and the IP / UDP (or UDP / IP)-based GTP-U protocol by utilizing the PDU Session generated by MWAB-UE. This is merely one example and does not limit the use of other protocols.

[0113] Figure 6 illustrates a handover scenario when the MWAB moves.

[0114] The MWAB (601) at the far left of FIG. 6 before handover is connected to a general gNB (602). When the MWAB (601) moves, the MWAB-UE can perform the handover procedure. Starting from the left of FIG. 6, the MWAB-UE can handover to another MWAB-gNB (610). The MWAB-UE can handover to an IAB-node (620). The MWAB-UE can handover to an MBRS (630). The MWAB-UE can handover to a general gNB (640).

[0115] Of the four cases described above, except for the case where the MWAB-UE handovers to a standard gNB (640), in the other cases, the MWAB must pass through a wireless link of at least 2 hops to transmit data to the 5GC. The MWAB (601) can only do 1 hop wireless backhaul. Therefore, among the four handover scenarios in FIG. 6, only the handover to the standard gNB (640) is possible, and handover is not possible in the other cases.

[0116] FIG. 7 is a diagram illustrating a terminal handover procedure using an interface between base stations according to the movement of a terminal according to one embodiment of the present disclosure.

[0117] In the handover preparation stage, the terminal may determine that a handover to another NG-RAN is necessary because the transmission signal from the terminal's Source NG-RAN has weakened. The terminal can determine the Target NG-RAN by transmitting the transmission signal strength from the surrounding NG-RAN to the Source NG-RAN. At this time, the Source NG-RAN and the Target NG-RAN transmit and receive information regarding the terminal's handover, and if the Target NG-RAN approves the terminal's handover, the handover execution stage can proceed.

[0118] In the Handover Execution phase, the Source NG-RAN can transmit user data received from the UPF or terminal to the Target NG-RAN.

[0119] If PLMN has configured secondary RAT usage reporting in Step 1a, Source NG-RAN can send the RAN usage data report to AMF during the Handover Execution phase.

[0120] In Step 1b, the Target NG-RAN may send an N2 Path Switch Request message to the AMF. This message may include the following data: List of PDU Sessions To Be Switched with N2 SM Information, List of PDU Sessions that failed to be established with the failure cause given in the N2 SM information element, UE Location Information, established QoS Flows status (active / not active) (for one of the following: congestion information monitoring, ECN marking for L4S at PSA UPF, ECN marking for L4S at NG-RAN), PDU Set Based Handling Support Indication included in the N2 SM information.

[0121] Additionally, if the terminal performs an MWAB operation, the message may include an S-NSSAI for the MWAB operation.

[0122] Target NG-RAN can request AMF to change the paths of PDU sessions in List Of PDU Sessions To Be Switched to Target NG-RAN, as the terminal has handed over to a new Target cell.

[0123] If the N2 Path Switch Request message received in Step 1b contains an S-NSSAI for MWAB operation, the AMF can perform the following operations.

[0124] If the type of the Target NG-RAN belongs to one of the following, the AMF may cancel the handover procedure by sending an N2 Path Switch Request Nack message to the Target NG-RAN; MWAB, IAB-node, or MBRS node. This message may include a Cause value, which is the reason for cancellation. The Cause value may have a value indicating that the handover is canceled because the terminal is an MWAB node.

[0125] If the Target NG-RAN is one of the MWAB, IAB-node, or MBRS node, the terminal handover procedure may be canceled.

[0126] A Target NG-RAN that receives an N2 Path Switch Request Nack message can notify the Source NG-RAN of the cancellation of the terminal handover, and the Source NG-RAN that receives this can search for a new Target NG-RAN.

[0127] The above procedure may also be performed during the Handover preparation procedure. That is, while the Source NG-RAN and Target NG-RAN are performing the terminal handover procedure during the Handover preparation procedure, the Target NG-RAN may identify the S-NSSAI for the MWAB among the S-NSSAIs requested by the terminal, and if the Target NG-RAN itself is one of the MWAB, IAB-node, or MBRS node, it may notify the Source NG-RAN and cancel the terminal handover.

[0128] In Step 2, the AMF may send an Nsmf_PDUSession_UpdateSMContext Request message to the SMF. This message may include the following values: N2 SM information received from T-RAN in Step 1b and N2 SM Information from source NG-RAN (Secondary RAT usage data), UE Location Information, and UE presence in the LADN service area.

[0129] This message allows the AMF to request the SMF to change the path of the list of PDU Sessions included in the N2 Path Switch Request message received from the Target NG-RAN from the existing Source NG-RAN to the Target NG-RAN.

[0130] In Step 3, the SMF may send an N4 Session Modification Request message to the UPF. This message may include the following information; AN Tunnel Info.

[0131] SMF can send AN Tunnel Info to UPF for the user data transmission downlink (DL) path changed from Source NG-RAN to Target NG-RAN.

[0132] In Step 4, the UPF may send an N4 Session Modification Response message to the SMF. This message may include the following information; CN Tunnel Info.

[0133] UPF can send CN Tunnel Info to SMF for the user data transmission uplink (uplink, UL) path changed from Source NG-RAN to Target NG-RAN.

[0134] In step 5, the UPF may send one or more "end markers" to the Source NG-RAN and / or the Source NG-RAN may send one or more "end markers" to the Target NG-RAN for reordering data in the Target NG-RAN.

[0135] In Step 6, the SMF may send an Nsmf_PDUSession_UpdateSMContext Response message to the AMF. This message may include the following information: N2 SM Information (CN Tunnel Info, updated CN PDB for the accepted QoS Flows, Updated TSCAIs for the accepted QoS Flows).

[0136] In Step 7, the AMF can send an N2 Path Switch Request Ack to the Target NG-RAN. This message may include the following: N2 SM Information, Failed PDU Sessions, and UE Radio Capability ID.

[0137] In step 8, the Target NG-RAN can notify the Source NG-RAN that the terminal handover procedure was successful by sending a Release Resources message to the Source NG-RAN.

[0138] In Step 9, the terminal may perform the Mobility Registration Update procedure if necessary (Registration Procedure).

[0139] FIG. 8 is a diagram illustrating a terminal handover procedure using an interface between a base station and an AMF according to an embodiment of the present disclosure as the terminal moves.

[0140] In Step 1, the S-RAN (Source NG-RAN, S-NG-RAN) may send a Hanover Required message to the S-AMF (Source-AMF). This message may include the following information: Target ID, Source to Target transparent container, SM N2 info list, PDU Session IDs, intra-system handover indication.

[0141] This message contains information transmitted from S-RAN to T-RAN (Target NG-RAN, T-NG-RAN). This information can be included in a Source to Target transparent container.

[0142] Additionally, if the terminal performs an MWAB operation, the message may include an S-NSSAI for the MWAB operation.

[0143] In Step 2, if the Target NG-RAN goes out of the S-AMF range, the S-AMF can perform T-AMF (Target-AMF) Selection.

[0144] If, in Step 2a, the S-AMF controls the T-RAN—that is, does not perform the T-AMF Selection of Step 2—and the S-AMF includes an S-NSSAI for the MWAB operation in the Handover Required message received in Step 1, the S-AMF can perform the following operations.

[0145] If the type of the Target NG-RAN belongs to one of the following, the S-AMF may cancel the handover procedure by sending a Handover Reject message to the Source NG-RAN; MWAB, IAB-node, or MBRS node. This message may include a Cause value, which is the reason for cancellation. The Cause value may be the value that the handover is canceled because the terminal is an MWAB node.

[0146] If the Target NG-RAN is one of the MWAB, IAB-node, or MBRS node, the terminal handover procedure may be canceled.

[0147] A Source NG-RAN that receives a Handover Reject message can cancel the terminal handover to the Target NG-RAN and search for a new Target NG-RAN.

[0148] In Step 3, the S-AMF may send a Namf_Communication_CreateUEContext Request message to the T-AMF. This message may include the following information: N2 Information (Target ID, Source to Target transparent container, SM N2 information list, PDU Session IDs), UE context information (SUPI, Service area restriction, Allowed NSSAI for each Access Type and Partially Allowed NSSAI if available, Tracing Requirements, LTE M Indication, the list of PDU Session IDs along with the corresponding SMF information and the corresponding S-NSSAI(s), PCF ID(s), DNN, UE Radio Capability ID and UE Radio Capability Information, N2 Notify URI.

[0149] If the S-AMF fails to control the Target NG-RAN in step 2, the S-AMF can transmit the information received from the S-RAN and terminal-related information to the T-AMF.

[0150] In Step 4, the T-AMF may send an Nsmf_PDUSession_UpdateSMContext Request message to the SMF. This message may include the following values: PDU Session ID, Target ID, T-AMF ID, and N2 SM Information.

[0151] In step 6a, the SMF may send an N4 Session Modification Request message to the UPF (PSA). This message may include the following information: CN Tunnel Info.

[0152] If the SMF selects a new intermediate UPF (I-UPF), it can send CN Tunnel Info (N9) with the I-UPF to the UPF (PSA).

[0153] In step 6b, the UPF (PSA) may send an N4 Session Modification Response message to the SMF. This message may include the following information: CN Tunnel Info.

[0154] If SMF selects a new intermediate UPF, UPF(PSA) can send CN Tunnel Info (N9) with I-UPF to SMF.

[0155] In Step 7, the SMF may send an Nsmf_PDUSession_UpdateSMContext Response message to the T-AMF. This message may include the following information: PDU Session ID, N2 SM Information, Reason for non-acceptance.

[0156] In Step 9, T-AMF may send a Handover Request message to T-RAN. This message may include the following: Source to Target transparent container, N2 MM Information, N2 SM Information list, Tracing Requirements, UE Radio Capability ID.

[0157] At Step 10, T-RAN may send a Handover Request Acknowledge message to T-AMF. This message may include the following information: Target to Source transparent container, List of PDU Sessions to Hand-over with N2 SM information, List of PDU Sessions that failed to be established with the failure cause given in the N2 SM information element, PDU Set Based Handling Support Indication included in the N2 SM information.

[0158] In step 11a, the T-AMF may send an Nsmf_PDUSession_UpdateSMContext Request message to the SMF. This message may include the following information: PDU Session ID, N2 SM response received from T-RAN (the N2 SM response received from T-RAN in step 10).

[0159] This message allows the AMF to request the SMF to change the path of the list of PDU Sessions included in the N2 Path Switch Request message received from the T-RAN from the existing Source NG-RAN to TG-RAN.

[0160] In step 11b, the SMF may send an N4 Session Modification Request message to the T-UPF (Target-UPF). This message may include the following information: T-RAN SM N3 forwarding Information list, indication to allocate DL forwarding tunnel(s) for indirect forwarding.

[0161] In step 11c, the T-UPF may send an N4 Session Modification Response message to the SMF. This message may include the following information: T-UPF SM N3 forwarding Information list.

[0162] At step 11d, the SMF may send an N4 Session Modification Request message to the S-UPF (Source-UPF). This message may include the following information: T-RAN SM N3 forwarding Information list or T-UPF SM N3 forwarding Information list, indication to allocate DL forwarding tunnel(s) for indirect forwarding.

[0163] At step 11e, S-UPF may send an N4 Session Modification Request message to SMF. This message may include the following information: S-UPF SM N3 forwarding Information list.

[0164] In step 11f, the SMF may send an Nsmf_PDUSession_UpdateSMContext Response message to the T-AMF. This message may include the following information: N2 SM Information.

[0165] At Step 12, T-AMF may send a Namf_Communication_CreateUEContext Response message to S-AMF. This message may include the following information: N2 information necessary for S-AMF to send Handover Command to S-RAN including Target to Source transparent container, PDU Sessions failed to be setup list, N2 SM information (N3 DL forwarding Information, PCF ID), [Target AMF ID].

[0166] FIG. 9 is a diagram illustrating a terminal handover procedure using an interface between a base station and an AMF according to an embodiment of the present disclosure as the terminal moves.

[0167] In Step 1, the S-RAN (Source NG-RAN, S-NG-RAN) may send a Hanover Required message to the S-AMF. This message may include the following information: Target ID, Source to Target transparent container, SM N2 info list, PDU Session IDs, intra-system handover indication.

[0168] This message contains information transmitted from S-RAN to T-RAN (Target NG-RAN, T-NG-RAN). This information can be included in a Source to Target transparent container.

[0169] Additionally, if the terminal performs an MWAB operation, the message may include an S-NSSAI for the MWAB operation.

[0170] In Step 2, if the Target NG-RAN goes out of the S-AMF (Source-AMF) range, the S-AMF can perform T-AMF Selection.

[0171] In Step 3, the S-AMF may send a Namf_Communication_CreateUEContext Request message to the T-AMF (Target-AMF). This message may include the following information: N2 Information (Target ID, Source to Target transparent container, SM N2 information list, PDU Session IDs), UE context information (SUPI, Service area restriction, Allowed NSSAI for each Access Type and Partially Allowed NSSAI if available, Tracing Requirements, LTE M Indication, the list of PDU Session IDs along with the corresponding SMF information and the corresponding S-NSSAI(s), PCF ID(s), DNN, UE Radio Capability ID and UE Radio Capability Information, N2 Notify URI.

[0172] If the S-AMF fails to control the Target NG-RAN in step 2, the S-AMF can transmit the information received from the S-RAN and terminal-related information to the T-AMF.

[0173] In Step 4, the T-AMF may send an Nsmf_PDUSession_UpdateSMContext Request message to the SMF. This message may include the following values: PDU Session ID, Target ID, T-AMF ID, and N2 SM Information.

[0174] In step 6a, the SMF may send an N4 Session Modification Request message to the UPF (PSA). This message may include the following information: CN Tunnel Info.

[0175] If the SMF selects a new intermediate UPF, it can send the CN Tunnel Info (N9) with the I-UPF to the UPF (PSA).

[0176] In step 6b, the UPF (PSA) may send an N4 Session Modification Response message to the SMF. This message may include the following information: CN Tunnel Info.

[0177] If SMF selects a new intermediate UPF, UPF(PSA) can send CN Tunnel Info (N9) with I-UPF to SMF.

[0178] In Step 7, the SMF may send an Nsmf_PDUSession_UpdateSMContext Response message to the T-AMF. This message may include the following information: PDU Session ID, N2 SM Information, Reason for non-acceptance.

[0179] In steps 8a and 8b, if the Handover Required message in step 1 contains an S-NSSAI for the MWAB operation, the T-AMF can perform the following actions.

[0180] If the type of the Target NG-RAN belongs to one of the following, the T-AMF may cancel the handover procedure by sending a Handover Reject message to the S-AMF; MWAB, IAB-node, or MBRS node. This message may include a Cause value, which is the reason for cancellation. The Cause value may have a value such that the handover is canceled because the terminal is an MWAB node.

[0181] If the Target NG-RAN is one of the MWAB, IAB-node, or MBRS node, the terminal handover procedure may be canceled.

[0182] Upon receiving the Handover Reject message, the S-AMF transmits this message to the Source NG-RAN, and the Source NG-RAN cancels the terminal handover to the Target NG-RAN and can search for a new Target NG-RAN.

[0183] In Step 9, T-AMF may send a Handover Request message to T-RAN. This message may include the following: Source to Target transparent container, N2 MM Information, N2 SM Information list, Tracing Requirements, UE Radio Capability ID.

[0184] At Step 10, T-RAN may send a Handover Request Acknowledge message to T-AMF. This message may include the following information: Target to Source transparent container, List of PDU Sessions to Hand-over with N2 SM information, List of PDU Sessions that failed to be established with the failure cause given in the N2 SM information element, PDU Set Based Handling Support Indication included in the N2 SM information.

[0185] In step 11a, the T-AMF may send an Nsmf_PDUSession_UpdateSMContext Request message to the SMF. This message may include the following information: PDU Session ID, N2 SM response received from T-RAN (the N2 SM response received from T-RAN in step 10).

[0186] This message allows the AMF to request the SMF to change the path of the list of PDU Sessions included in the N2 Path Switch Request message received from the T-RAN from the existing Source NG-RAN to TG-RAN.

[0187] In step 11b, the SMF may send an N4 Session Modification Request message to the T-UPF (Target-UPF). This message may include the following information: T-RAN SM N3 forwarding Information list, indication to allocate DL forwarding tunnel(s) for indirect forwarding.

[0188] In step 11c, the T-UPF may send an N4 Session Modification Response message to the SMF. This message may include the following information: T-UPF SM N3 forwarding Information list.

[0189] At step 11d, the SMF may send an N4 Session Modification Request message to the S-UPF. This message may include the following information: T-RAN SM N3 forwarding Information list or T-UPF SM N3 forwarding Information list, indication to allocate DL forwarding tunnel(s) for indirect forwarding.

[0190] At step 11e, S-UPF may send an N4 Session Modification Request message to SMF. This message may include the following information: S-UPF SM N3 forwarding Information list.

[0191] In step 11f, the SMF may send an Nsmf_PDUSession_UpdateSMContext Response message to the T-AMF. This message may include the following information: N2 SM Information.

[0192] At Step 12, T-AMF may send a Namf_Communication_CreateUEContext Response message to S-AMF. This message may include the following information: N2 information necessary for S-AMF to send Handover Command to S-RAN including Target to Source transparent container, PDU Sessions failed to be setup list, N2 SM information (N3 DL forwarding Information, PCF ID), [Target AMF ID].

[0193] FIG. 10 illustrates the configuration of a terminal according to embodiments of the present disclosure.

[0194] A terminal according to one embodiment of the present disclosure may include a processor (1020) that controls the overall operation of the terminal, a transceiver (1000) including a transmitter and a receiver, and a memory (1010). Of course, it is not limited to the examples described above, and the terminal may include more configurations than those shown in FIG. 10, or fewer configurations.

[0195] According to one embodiment of the present disclosure, the transceiver (1000) can transmit and receive signals with network entities or other terminals. The signals transmitted and received with network entities may include control information and data. Additionally, the transceiver (1000) can receive a signal through a wireless channel and output it to a processor (1020), and transmit the signal output from the processor (1020) through a wireless channel.

[0196] According to one embodiment of the present disclosure, the processor (1020) can control the terminal to perform any one of the above-described embodiments. Meanwhile, the processor (1020), memory (1010), and transceiver (1000) do not necessarily have to be implemented as separate modules, and can be implemented as a single component in the form of a single chip. Also, the processor (1020) and the transceiver (1000) can be electrically connected. Additionally, the processor (1020) may include an application processor (AP), a communication processor (CP), a circuit, an application-specific circuit, a controller, or at least one processor.

[0197] According to one embodiment of the present disclosure, the memory (1010) may store data such as a basic program, an application program, and setting information for the operation of a terminal. In particular, the memory (1010) provides the stored data upon a request from the processor (1020). The memory (1010) may be composed of a storage medium or a combination of storage media such as ROM, RAM, a hard disk, a CD-ROM, and a DVD. Additionally, the memory (1010) may be a plurality of. Furthermore, the processor (1020) may perform the aforementioned embodiments based on a program for performing the aforementioned embodiments of the present disclosure stored in the memory (1010).

[0198] FIG. 11 illustrates the configuration of a base station or network entity according to embodiments of the present disclosure.

[0199] A network entity according to one embodiment of the present disclosure may include a processor (1120) that controls the overall operation of the network entity, a transceiver (1100) including a transmitter and a receiver, and a memory (1110). Of course, it is not limited to the examples described above, and the network entity may include more configurations than the configuration shown in FIG. 11, or fewer configurations.

[0200] According to one embodiment of the present disclosure, the transmitting and receiving unit (1100) can transmit and receive a signal with at least one of other network entities or terminals. The signal transmitted and received with at least one of other network entities or terminals may include control information and data.

[0201] According to one embodiment of the present disclosure, the processor (1120) can control a network entity to perform any one of the above-described embodiments. Meanwhile, the processor (1120), memory (1110), and transceiver (1100) do not necessarily have to be implemented as separate modules, and can be implemented as a single component in the form of a single chip. Also, the processor (1120) and the transceiver (1100) can be electrically connected. Additionally, the processor (1120) may include an application processor (AP), a communication processor (CP), a circuit, an application-specific circuit, a controller, or at least one processor.

[0202] According to one embodiment of the present disclosure, the memory (1110) may store data such as a basic program, an application program, and configuration information for the operation of a network entity. In particular, the memory (1110) provides the stored data upon request by the processor (1120). The memory (1110) may be composed of a storage medium or a combination of storage media such as ROM, RAM, a hard disk, a CD-ROM, and a DVD. Additionally, the memory (1110) may be a plurality of. Furthermore, the processor (1120) may perform the aforementioned embodiments based on a program for performing the aforementioned embodiments of the present disclosure stored in the memory (1110).

[0203] It should be noted that the aforementioned configuration diagrams, exemplary diagrams of control / data signal transmission methods, exemplary diagrams of operation procedures, and configuration diagrams are not intended to limit the scope of the rights of the present disclosure. That is, all components, entities, or steps of operation described in the embodiments of the present disclosure should not be interpreted as essential components for the implementation of the disclosure, and may be implemented within a scope that does not impair the essence of the disclosure even if only some components are included. Furthermore, each embodiment may be combined and operated as needed. For example, parts of the methods proposed in the present disclosure may be combined to operate network entities and terminals.

[0204] The operations of the base station or terminal described above can be realized by providing a memory device storing the corresponding program code in any component within the base station or terminal device. That is, the control unit of the base station or terminal device can execute the operations described above by reading the program code stored in the memory device using a processor or CPU (Central Processing Unit) and executing it.

[0205] Various components of entities, base stations, or terminal devices and modules described herein may be operated using hardware circuits, such as, for example, complementary metal oxide semiconductor-based logic circuits, firmware, software, and / or a combination of hardware and firmware and / or software embedded in a machine-readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates, and application-specific semiconductors.

[0206] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the claims or embodiments described in the specification of this disclosure.

[0207] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), Electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disc storage devices, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0208] Additionally, the above program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0209] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0210] Meanwhile, although specific embodiments have been described in the detailed description of this disclosure, it is understood that various modifications are possible within the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof. In other words, it is obvious to those skilled in the art that other modifications based on the technical concept of this disclosure are possible. Furthermore, each of the above embodiments may be combined and operated as needed. For example, parts of the methods proposed in this disclosure may be combined to operate a base station and a terminal. Additionally, while the above embodiments have been presented based on 5G and NR systems, other modifications based on the technical concept of the above embodiments may be implemented in other systems such as LTE, LTE-A, and LTE-A-Pro systems.

Claims

1. A method performed by a source RAN (radio access network) of a wireless communication system, A step of transmitting a handover required message containing a PDU (protocol data unit) session ID (identifier) ​​to a source AMF (access and mobility management function), and The method includes the step of receiving a message containing a cause associated with a handover failure from the target AMF through the source AMF, and A method characterized in that the above cause indicates that the S-NSSAI (single-network slice selection assistance information) corresponding to the above PDU session ID cannot be used at the MWAB (mobile gNB (gNodeB) with wireless access backhauling) node.

2. In Paragraph 1, A method characterized in that the handover fails when the target RAN is the MWAB node and the S-NSSAI is not supported by the MWAB node.

3. In Paragraph 1, A method characterized in that the handover requirement message includes a target ID indicating a target RAN, and the target ID is included in a UE (user equipment) context message and transmitted to the target AMF.

4. A method performed by the source AMF (access and mobility management function) of a wireless communication system, A step of receiving a handover required message containing a PDU (protocol data unit) session ID (identifier) ​​from a source RAN (radio access network); Step of selecting a target AMF for handover; A step of transmitting a UE (user equipment) context request message to the selected target AMF, the message including the PDU session ID and S-NSSAI (single-network slice selection assistance information) corresponding to the PDU session ID; A step of receiving a message from the target AMF containing a cause associated with the failure of the handover, wherein the cause indicates that the S-NSSAI cannot be used at the MWAB (mobile gNB(gNodeB) with wireless access backhauling) node; and A method comprising the step of transmitting a message containing the cause to the source RAN.

5. In Paragraph 4, A method characterized in that the handover fails when the target RAN is the MWAB node and the S-NSSAI is not supported by the MWAB node.

6. In Paragraph 4, A method characterized in that the handover requirement message includes a target ID indicating a target RAN, and the target ID is included in the UE (user equipment) context message and transmitted to the target AMF.

7. A method performed by a target AMF (access and mobility management function) of a wireless communication system, A step of receiving a UE (user equipment) context request message from a source AMF that has received a handover required message, the message including a PDU (protocol data unit) session ID (identifier) ​​and S-NSSAI (single-network slice selection assistance information) corresponding to the PDU session ID; and The method includes the step of transmitting a message containing a cause associated with the failure of the handover to the source RAN (radio access network) through the source AMF, and A method characterized by the above cause indicating that the above S-NSSAI cannot be used in a MWAB (mobile gNB (gNodeB) with wireless access backhauling) node.

8. In Paragraph 7, If the target RAN is the MWAB node and the S-NSSAI is not supported by the MWAB node, the handover fails, and A method characterized in that the handover requirement message includes a target ID indicating the target RAN, and the target ID is included in the UE (user equipment) context message and transmitted to the target AMF.

9. In the source RAN (radio access network) of a wireless communication system, At least one transceiver; At least one processor connected to the above at least one transceiver so as to be able to communicate; and The source RAN is connected to communicate with at least one processor and is executable individually or in any combination on the at least one processor, so that the source RAN As the source AMF (access and mobility management function), send a handover required message containing a PDU (protocol data unit) session ID (identifier), and It includes a memory that stores a command to receive a message containing a cause associated with a handover failure from the target AMF through the source AMF; and Source RAN characterized by the above cause indicating that S-NSSAI (single-network slice selection assistance information) corresponding to the above PDU session ID cannot be used at the MWAB (mobile gNB (gNodeB) with wireless access backhauling) node.

10. In Paragraph 9, Source RAN characterized in that the handover fails when the target RAN is the MWAB node and the S-NSSAI is not supported by the MWAB node.

11. In Paragraph 9, A source RAN characterized in that the above handover requirement message includes a target ID indicating a target RAN, and the target ID is included in a UE (user equipment) context message and transmitted to the target AMF.

12. In the source AMF (access and mobility management function) of a wireless communication system, At least one transceiver; At least one processor connected to the above at least one transceiver so as to be able to communicate; and The source AMF is connected to communicate with at least one processor and is executable individually or in any combination on the at least one processor, so that the source AMF, Receive a handover required message containing a PDU (protocol data unit) session ID (identifier) ​​from the source RAN (radio access network), and Select the target AMF for the handover, A UE (user equipment) context request message including the PDU session ID and S-NSSAI (single-network slice selection assistance information) corresponding to the PDU session ID is transmitted to the above-mentioned selected target AMF, and Receive a message from the above target AMF containing a cause associated with the failure of the handover, and It includes a memory that stores a command to transmit a message containing the cause to the source RAN; and Source AMF characterized by the above cause indicating that the above S-NSSAI cannot be used in an MWAB (mobile gNB (gNodeB) with wireless access backhauling) node.

13. In Paragraph 12, If the target RAN is the MWAB node and the S-NSSAI is not supported by the MWAB node, the handover fails, and A source AMF characterized in that the above handover requirement message includes a target ID indicating a target RAN, and the target ID is included in the UE (user equipment) context message and transmitted to the target AMF.

14. In the target AMF (access and mobility management function) of a wireless communication system, At least one transceiver; At least one processor connected to the above at least one transceiver so as to be able to communicate; and The target AMF is connected to communicate with the at least one processor and can be executed individually or in any combination on the at least one processor, so that the target AMF, From a source AMF that has received a handover required message, a UE (user equipment) context request message is received that includes a PDU (protocol data unit) session ID (identifier) ​​and S-NSSAI (single-network slice selection assistance information) corresponding to the PDU session ID, and It includes a memory that stores a command to transmit a message containing a cause associated with a handover failure to the source RAN (radio access network) through the source AMF; and The above cause is characterized by indicating that the above S-NSSAI cannot be used in an MWAB (mobile gNB (gNodeB) with wireless access backhauling) node, a target AMF.

15. In Paragraph 14, If the target RAN is the MWAB node and the S-NSSAI is not supported by the MWAB node, the handover fails, and A target AMF characterized in that the handover requirement message includes a target ID indicating the target RAN, and the target ID is included in the UE (user equipment) context message and transmitted to the target AMF.

Images