METHOD AND APPARATUS FOR REVOKING USER EQUIPMENT AUTHENTICATION IN WIRELESS COMMUNICATION SYSTEM

A method for discarding authentication of a user equipment in a wireless communication system, including: determining, by a network, authentication revocation of a first remote user equipment; determining whether or not a PDU session of a relay user equipment, which is used by the first remote user equipment, is used by another remote user equipment; and transmitting, to the relay user equipment, a release request for the PDU session of the relay user equipment or a release request for a PC5 link of the first remote user equipment.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2022-0002893, filed on Jan. 7, 2022, the contents of which are hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a wireless communication system, that is, to a method for revoking authentication of a user equipment. More particularly, the present disclosure relates to a method for revoking secondary authentication of a remote user equipment (UE) that performs communication with a core network based on UE-network relay.

Description of the Related Art

In particular, as a large number of communication devices require a large communication capacity, the enhanced mobile broadband (eMBB) communication technology, as compared to the conventional radio access technology (RAT), is being proposed. In addition, not only massive machine type communications (massive MTC), which provide a variety of services anytime and anywhere by connecting multiple devices and objects, but also a communication system considering a service/user equipment (UE) sensitive to reliability and latency is being proposed. Various technical configurations for this are being proposed.

SUMMARY

The present disclosure may provide a method and apparatus for revoking authentication of a user equipment in a wireless communication system.

The present disclosure may provide a method and apparatus for revoking authentication for a remote user equipment (UE) that performs communication with a core network through a relay UE based on UE-network relay in a wireless communication system.

The present disclosure may provide a method and apparatus for determining whether or not to maintain a packet data unit (PDU) session of a relay UE, in case of revoking secondary authentication for a remote UE in a wireless communication system.

The present disclosure may provide a method and apparatus for determining a subject determining whether or not to maintain a PDU session of a relay UE based on revocation of secondary authentication for a remote UE in a wireless communication system.

The technical objects to be achieved in the present disclosure are not limited to the above-mentioned technical objects, and other technical objects that are not mentioned may be considered by those skilled in the art through the embodiments described below.

The present disclosure may provide a method for discarding authentication of a user equipment in a wireless communication system, the method comprising: determining, by a network, revocation of authentication of a first remote user equipment, determining whether another remote user equipment uses a packet data unit (PDU) session of a relay user equipment, which the first remote user equipment is using, and transmitting a release request for a PDU session of a relay user equipment or a release request for a PC5 link of the first remote user equipment to the relay user equipment.

The present disclosure may provide based on the PDU session of the relay user equipment being used only by the first remote user equipment, but not by the another remote user equipment, the network transmits, to the relay user equipment, the release request for the PDU session of the relay user equipment.

The present disclosure may provide based on the PDU session of the relay user equipment being used not only by the first remote user equipment but also by the another remote user equipment, the network transmits the release request for the PC5 link of the first remote user equipment.

The present disclosure may provide the revocation of authentication of the first remote user equipment is determined by a session management function (SMF) or data network-authentication, authorization and accounting (DN-AAA).

The present disclosure may provide based on the revocation of authentication of the first remote user equipment being determined based on the DN-AAA, the SMF receives an authentication revocation request message for the first remote user equipment from the DN-AAA.

The present disclosure may provide based on the network performing authentication for at least one remote user equipment through the relay user equipment, the network obtains identification information and relevant information on each of the at least one remote user equipment through the relay user equipment.

The present disclosure may provide the network determines whether or not the another remote user equipment different from the first remote user equipment uses the PDU session of the relay user equipment, based on the identification information and the relevant information on the each of the at least one remote user equipment.

The present disclosure may provide based on the network transmitting the release request for the PDU session of the relay user equipment, the release request for the PDU session of the relay user equipment includes a release cause value, and wherein the release cause value indicates authentication revocation for the first remote user equipment.

The present disclosure may provide based on the release request for the PDU session of the relay user equipment, the relay user equipment performs a procedure of releasing the PC5 link with the first remote user equipment, releases the PDU session and reports PDU session release completion to the network.

The present disclosure may provide based on the network transmitting the release request for the PC5 link of the first remote user equipment to the relay user equipment, the release request for the PC5 link of the first remote user equipment includes identification information of the first remote user equipment and a release cause value indicating the authentication revocation of the first remote user equipment.

The present disclosure may provide the relay user equipment performs a procedure for releasing the PC5 link with the first remote user equipment based on the identification information of the first remote user equipment and reports PC5 link release completion of the first remote user equipment to the network.

The present disclosure may provide a network operating in a wireless communication system, the network comprising, at least one transceiver, at least one processor and at least one memory coupled with the at least one processor in an operable manner and configured, when operated, to store instructions for the at least one processor to implement a specific operation, wherein the specific operation is configured to: determine authentication revocation of a first remote user equipment, determine whether another remote user equipment uses a PDU session of a relay user equipment, which the first remote user equipment is using, and control the transceiver to transmit a release request for the PDU session of the relay user equipment or a release request for a PC5 link of the first remote user equipment to a relay user equipment.

The present disclosure may provide a method for performing authentication discarding of a user equipment in a wireless communication system, the method comprising: receiving, from a network, a release request for a PDU session of a relay user equipment or a release request for a PC5 link of a first remote user equipment, and performing a procedure of releasing the PC5 link with the first remote user equipment based on the release request for the PDU session of the relay user equipment or the release request for the PC5 link of the first remote user equipment, wherein authentication revocation of the first remote user equipment is determined based on the network, and wherein the release request for the PDU session of the relay user equipment or the release request for the PC5 link of the first remote user equipment is received based on whether or not another remote user equipment uses the PDU session of the relay user equipment, which the first remote user equipment is using.

The present disclosure may provide a relay user equipment operating in a wireless communication system, the relay user equipment comprising: at least one transceiver, at least one processor, and at least one memory coupled with the at least one processor in an operable manner and configured, when operated, to store instructions for the at least one processor to implement a specific operation, wherein the specific operation is configured to: control the transceiver to receive, from a network, a release request for a PDU session of a relay user equipment or a release request for a PC5 link of a first remote user equipment, and perform a procedure of releasing the PC5 link with the first remote user equipment based on the release request for the PDU session of the relay user equipment or the release request for the PC5 link of the first remote user equipment, and wherein authentication revocation of the first remote user equipment is determined based on the network, and the release request for the PDU session of the relay user equipment or the release request for the PC5 link of the first remote user equipment is received based on whether or not another remote user equipment uses the PDU session of the relay user equipment, which the first remote user equipment is using.

The present disclosure may provide a method for revoking authentication of a UE in a wireless communication system.

The present disclosure may provide a method for revoking authentication for a remote UE that performs communication with a core network through a relay UE based on UE-network relay in a wireless communication system.

The present disclosure may provide a method for maintaining a relay service of another remote UE using a PDU session of a relay UE, in case of revoking secondary authentication for a remote UE in a wireless communication system.

The technical objects to be achieved in the present disclosure are not limited to the above-mentioned technical objects, and other technical objects that are not mentioned may be considered by those skilled in the art through the embodiments described below.

Effects obtained in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly derived and understood by those skilled in the art, to which a technical configuration of the present disclosure is applied, from the following description of embodiments of the present disclosure. That is, effects, which are not intended when implementing a configuration described in the present disclosure, may also be derived by those skilled in the art from the embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Following embodiments are achieved by combination of structural elements and features of the present disclosure in a predetermined manner. Each of the structural elements or features should be considered selectively unless specified separately. Each of the structural elements or features may be carried out without being combined with other structural elements or features. Also, some structural elements and/or features may be combined with one another to constitute the embodiments of the present disclosure. The order of operations described in the embodiments of the present disclosure may be changed. Some structural elements or features of one embodiment may be included in another embodiment, or may be replaced with corresponding structural elements or features of another embodiment.

In the description of the drawings, procedures or steps which render the scope of the present disclosure unnecessarily ambiguous will be omitted and procedures or steps which can be understood by those skilled in the art will be omitted.

In the entire specification, when a certain portion “comprises” or “includes” a certain component, this indicates that the other components are not excluded, but may be further included unless specially described. The terms “unit”, “-or/er” and “module” described in the specification indicate a unit for processing at least one function or operation, which may be implemented by hardware, software and a combination thereof In addition, “a or an”, “one”, “the” and similar related words may be used as the sense of including both a singular representation and a plural representation unless it is indicated in the context describing the present specification (especially in the context of the following claims) to be different from this specification or is clearly contradicted by the context.

In this specification, the embodiments of the present disclosure are described with focus on the relationship of data reception and transmission between a base station and a mobile station. Herein, the base station means a terminal node of a network that performs direct communication with the mobile station. In this document, a specific operation, which is described to be performed by a base station, may be performed by an upper node of the base station in some cases.

That is, in a network consisting of a plurality of network nodes including a base station, various operations for communicating with a mobile station may be performed by the base station or network nodes other than the base station. Herein, “base station” may be replaced by such terms as “fixed station”, “Node B”, “eNode B(eNB)”, “gNode B(gNB)”, “ng-eNB”, “advanced base station(ABS)”, or “access point”.

Also, in the embodiments of the present disclosure, “terminal” may be replaced by such terms as “user equipment(UE)”, “mobile station(MS)”, “subscriber station(SS)”, “mobile subscriber station(MSS)”, “mobile terminal” or “advanced mobile station(AMS)”.

In addition, a transmission end refers to a fixed and/or mobile node that provides a data service or a voice service, and a reception end means a fixed and/or mobile node that receives a data service or a voice service. Accordingly, in the case of an uplink, a mobile station may be a transmission end, and a base station may be a reception end. Likewise, in the case of a downlink, a mobile station may be a reception end, and a base station may be a transmission end.

The embodiments of the present disclosure may be supported by standard documents disclosed in at least one of the following radio access systems: an IEEE 802 xx system, a 3rd generation partnership project (3GPP) system, a 3GPP long term evolution (LTE) system, a 3GPP 5th generation (5G) new radio (NR) system and a 3GPP2 system, and in particular, the embodiments of the present disclosure may be supported by the following documents: 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321, and 3GPP TS 38.331.

In addition, the embodiments of the present disclosure are applicable to another radio access system but is not limited to the above-described system. As an example, they are applicable to a system applied after a 3GPP 5G NR system and are not limited to a specific system.

That is, obvious steps and parts not described in the embodiments of the present disclosure may be described with reference to the above documents. In addition, all the terms disclosed in this document may be explained by the standard document.

Hereinafter, a preferred embodiment according to the present disclosure will be described in detail with reference to accompanying drawings. Detailed descriptions disclosed below together with accompanying drawings are intended to describe example embodiments of the present disclosure and not intended to show any sole embodiment in which a technical configuration of the present disclosure can be implemented.

In addition, specific terms used in the embodiments of the present disclosure are provided to help understand the present disclosure, and such specific terms may be used in any other modified forms without departing from the technical idea of the present disclosure.

The following technology may be applied to various radio 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) and the like.

For clarity of explanation, the descriptions below are based on a 3GPP communication system (e.g. LTE, NR and the like), but the technical idea of the present disclosure is not limited thereto. LTE may mean a technology after 3GPP TS 36.xxx Release 8. Specifically, the LTE technology after 3GPP TS 36.xxx Release 10 may be referred to as LTE-A, and the one after 3GPP TS 36.xxx Release 13 may be referred to as LTE-A pro. 3GPP NR may mean a technology after TS 38.xxx Release 15. 3GPP 6G may mean a technology after TS Release 17 and/or Release 18. “xxx’ means the specific number of a standard document. LTE/NR/6G may be referred to collectively as 3GPP system.

Contents described in standard documents released earlier than the present disclosure may be referred to for the background art, terms and abbreviations used in the present disclosure. As an example, 36.xxx and 38.xxx standard documents may be referred to.

For terms, abbreviations, and other backgrounds that may be used in this document, reference may be made to the following standard document descriptions published prior to this document. In particular, terms, abbreviations, and other background technologies related to LTE/EPS (Evolved Packet System) may refer to 36.xxx series, 23.xxx series, and 24.xxx series, and NR (new radio)/5GS related terms and abbreviations and other backgrounds may refer to the 38.xxx series, 23.xxx series and 24.xxx series.

3GPP LTE/EPS3GPP TS 36.211: Physical channels and modulation3GPP TS 36.212: Multiplexing and channel coding3GPP TS 36.213: Physical layer procedures3GPP TS 36.214: Physical layer; Measurements3GPP TS 36.300: Overall description3GPP TS 36.304: User Equipment (UE) procedures in idle mode3GPP TS 36.306: User Equipment (UE) radio access capabilities3GPP TS 36.314: Layer 2—Measurements3GPP TS 36.321: Medium Access Control (MAC) protocol3GPP TS 36.322: Radio Link Control (RLC) protocol3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)3GPP TS 36.331: Radio Resource Control (RRC) protocol3GPP TS 36.413: S1 Application Protocol (S1AP)3GPP TS 36.423: X2 Application Protocol (X2AP)3GPPP TS 22.125: Unmanned Aerial System support in 3GPP; Stage 13GPP TS 23.303: Proximity-based services (Prose); Stage 23GPP TS 23.401: General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access3GPP TS 23.402: Architecture enhancements for non-3GPP accesses3GPP TS 23.286: Application layer support for V2X services; Functional architecture and information flows3GPP TS 24.301: Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 33GPP TS 24.302: Access to the 3GPP Evolved Packet Core (EPC) via non-3GPP access networks; Stage 33GPP TS 24.334: Proximity-services (ProSe) User Equipment (UE) to ProSe function protocol aspects; Stage 33GPP TS 24.386: User Equipment (UE) to V2X control function; protocol aspects; Stage 3

3GPP NR/5GS3GPP TS 38.211: Physical channels and modulation3GPP TS 38.212: Multiplexing and channel coding3GPP TS 38.213: Physical layer procedures for control3GPP TS 38.214: Physical layer procedures for data3GPP TS 38.215: Physical layer measurements3GPP TS 38.300: NR and NG-RAN Overall Description3GPP TS 38.304: User Equipment (UE) procedures in idle mode and in RRC inactive state3GPP TS 38.321: Medium Access Control (MAC) protocol3GPP TS 38.322: Radio Link Control (RLC) protocol3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)3GPP TS 38.331: Radio Resource Control (RRC) protocol3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)3GPP TS 37.340: Multi-connectivity; Overall description3GPP TS 23.501: System Architecture for the 5G System3GPP TS 23.502: Procedures for the 5G System3GPP TS 23.503: Policy and Charging Control Framework for the 5G System;

3GPP TS 24.502: Access to the 3GPP 5G Core Network (5GCN) via non-3GPP access networks3GPP TS 24.526: User Equipment (UE) policies for 5G System (5GS); Stage 3

Hereinafter, the present disclosure is described based on the terms defined as above.

Three major requirement areas of 5G include (1) an enhanced mobile broadband (eMBB) area, (2) a massive machine type communication (mMTC) area, and (3) an ultra-reliable and low latency communications (URLLC) area.

Some use cases may require multiple areas for optimization, and other use case may be focused on only one key performance indicator (KPI). 5G supports these various use cases in a flexible and reliable method.

5G System Architecture to which the Present Disclosure is Applicable

A 5G system is an advanced technology from 4G LTE mobile communication technology and supports a new radio access technology (RAT), extended long term evolution (eLTE) as an extended technology of LTE, non-3GPP access (e.g., wireless local area network (WLAN) access), etc. through the evolution of the existing mobile communication network structure or a clean-state structure.

The 5G system is defined based on a service, and an interaction between network functions (NFs) in an architecture for the 5G system can be represented in two ways as follows.

Reference point representation: indicates an interaction between NF services in NFs described by a point-to-point reference point (e.g., N11) between two NFs (e.g., AMF and SMF).

Service-based representation: network functions (e.g., AMF) within a control plane (CP) allow other authenticated network functions to access its services. The representation also includes a point-to-point reference point, if necessary.

Overview of 3GPP System

An example of the network structure ofFIG.1discloses an LTE/EPS-based network structure, and may operate with reference to matters described in standard documents published before this document. In the network structure ofFIG.1, at least one of SGW, PDN GW, MME, SGSN, and ePDG entities may operate with reference to matters described in standard documents published before this document. In addition, S1-MME, S1-U, S2a, S2b, S3, S4, S5, S11, and SGi may exist as interfaces between each entity, which are described in the standard document published before this document. can do. In addition, other entities and interfaces may be configured with reference to matters described in standard documents published before this document described above, and are not limited to specific forms.

FIG.2illustrates an example of a network structure of an evolved universal terrestrial radio access network (E-UTRAN) to which the present disclosure is applicable. An E-UTRAN system is an evolved version of the existing UTRAN system and may be, for example, 3GPP LTE/LTE-A system. Communication networks are widely deployed to provide various communication services such as voice (e.g., voice over Internet protocol (VoIP)) through IMS and packet data.

Referring toFIG.2, an E-UMTS network includes an E-UTRAN, an EPC, and one or more UEs. The E-UTRAN consists of eNBs that provide control plane and user plane protocols to the UE, and the eNBs are interconnected with each other by means of the X2 interface, and reference may be made to matters described in standard documents published before this document.

FIG.3is a view illustrating a general E-URTAN and an example of an architecture of an evolved packet core (EPC).

As illustrated inFIG.3, the eNB can perform functions such as routing to gateway while radio resource control (RRC) connection is activated, scheduling and transmission of paging messages, scheduling and transmission of a broadcast channel (BCH), dynamic allocation of resources in uplink and downlink to the UE, configuration and provision for the measurement of the eNB, radio bearer control, radio admission control, and connection mobility control. The eNB can perform functions such as paging situation in the EPC, management of an LTE IDLE state, ciphering of a user plane, SAE bearer control, and ciphering and integrity protection of NAS signaling.

Annex J of 3GPP TR 23.799 shows various architectures combining 5G and 4G. And 3GPP TS 23.501 shows an architecture using NR and NGC.

FIG.4is a view illustrating an example of a structure of a radio interface protocol in a control plane between user equipment (UE) and evolved node B (eNB), andFIG.5is view illustrating an example of a structure of a radio interface protocol in a user plane between UE and eNB.

The radio interface protocol is based on 3GPP radio access network standard. The radio interface protocol horizontally consists of a physical layer, a data link layer, and a network layer, and is vertically divided into a user plane for data information transmission and a control plane for control signaling delivery.

The protocol layers may be divided into L1 (first layer), L2 (second layer), and L3 (third layer) based upon three lower layers of an open system interconnection (OSI) standard model that is well known in the art of communication systems, and it is possible to refer to the matters described in the standard document published before this document described above.

FIG.6is a view illustrating an example of a wireless communication system that is applied to the present disclosure.

5GC (5G Core) may include various components, part of which are shown inFIG.6, including an access and mobility management function (AMF)410, a session management function (SMF)420, a policy control function (PCF)430, a Prose user plane function (UPF)440, an application function (AF)450, unified data management (UDM)460, and a non-3GPP interworking function (N3IWF)490.

A UE100is connected to a data network via the UPF440through a next generation radio access network (NG-RAN) including the gNB300. The UE100may be provided with a data service even through untrusted non-3GPP access, e.g., a wireless local area network (WLAN). In order to connect the non-3GPP access to a core network, the N3IWF490may be deployed.

The N3IWF490performs a function of managing interworking between the non-3GPP access and the 5G system. When the UE100is connected to non-3GPP access (e.g., WiFi referred to as IEEE 801.11), the UE100may be connected to the 5G system through the N3IWF490. The N3IWF490performs control signaling with the AMF410and is connected to the UPF440through an N3 interface for data transmission.

The AMF410may manage access and mobility in the 5G system. The AMF410may perform a function of managing (non-access stratum) NAS security. The AMF410may perform a function of handling mobility in an idle state.

The UPF440performs a function of gateway for transmitting and receiving user data. The UPF node440may perform the entirety or a portion of a user plane function of a serving gateway (S-GW) and a packet data network gateway (P-GW) of 4G mobile communication.

The UPF440is a component that operates as a boundary point between a next generation radio access network (NG-RAN) and the core network and maintains a data path between the gNB300and the SMF420. In addition, when the UE100moves over an area served by the gNB300, the UPF440serves as a mobility anchor point. The UPF440may perform a function of handling a PDU. For mobility within the NG-RAN (which is defined after 3GPP Release-15), the UPF440may route packets. In addition, the UPF440may also serve as an anchor point for mobility with another 3GPP network (RAN defined before 3GPP Release-15, e.g., universal mobile telecommunications system (UMTS) terrestrial radio access network (UTRAN), evolved (E)-UTRAN or global system for mobile communication (GERAN)/enhanced data rates for global evolution (EDGE) RAN. The UPF440may correspond to a termination point of a data interface toward the data network.

The PCF430is a node that controls an operator's policy. The AF450is a server for providing various services to the UE100. The UDM460is a server that manages subscriber information, such as home subscriber server (HSS) of 4G mobile communication. The UDM460stores and manages the subscriber information in a unified data repository (UDR).

The SMF420may perform a function of allocating an Internet protocol (IP) address of the UE100. In addition, the SMF420may control a packet data unit (PDU) session.

For convenience of explanation, hereinafter, reference numerals may be omitted for AMF410, SMF420, PCF430, UPF440, AF450, UDM460, N3IWF490, gNB300, or UE100, which may operate with reference to contents described in standard documents released earlier than the present document.

FIG.7is a view illustrating an example expressing a structure of a wireless communication system, which is applied to the present disclosure, from a node perspective.

Referring toFIG.7, a UE is connected to a data network (DN) through a next generation RAN. A control plane function (CPF) node performs all or a part of the functions of a mobility management entity (MME) of 4G mobile communication and all or a part of serving gateway (S-GW) and PDN gateway (P-GW) functions. The CPF node includes AMF and SMF.

A UPF node performs a function of a gateway in which data of a user is transmitted and received.

An authentication server function (AUSF) authenticates and manages a UE. A network slice selection function (NSSF) is a node for network slicing described below.

A network exposure function (NEF) provides a mechanism that safely opens the service and function of 5G core.

Reference points inFIG.7are described as follows. N1 represents a reference point between UE and AMF. N2 represents a reference point between (R)AN and AMF. N3 represents a reference point between (R)AN and UPF. N4 represents a reference point between SMF and UPF. N5 represents a reference point between PCF and AF. N6 represents a reference point between UPF and DN. N7 represents a reference point between SMF and PCF. N8 represents a reference point between UDM and AMF. N9 represents a reference point between UPFs. N10 represents a reference point between UDM and SMF. N11 represents a reference point between AMF and SMF. N12 represents a reference point between AMF and AUSF. N13 represents a reference point between UDM and AUSF. N14 represents a reference point between AMFs. N15 represents a reference point between PCF and AMF in a non-roaming scenario and a reference point between AMF and PCF of a visited network in a roaming scenario. N16 represents a reference point between SMFs. N22 represents a reference point between AMF and NSSF. N30 represents a reference point between PCF and NEF. N33 may represent a reference point between AF and NEF, and the above-described entity and interface may be configured with reference to contents described in standard documents released earlier than the present document.

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

The protocol layers may be divided into L1 (layer-1), L2 (layer-2), and L3 (layer-3) based on the three lower layers of the open system interconnection (OSI) reference model widely known in communication systems.

Hereinafter, the present disclosure will describe each layer of a radio protocol.FIG.8is a view illustrating an example of a radio interface protocol between UE and gBN.

Referring toFIG.8, an access stratum (AS) layer may include a physical (PHY) layer, a medium access control layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer, and an operation based on each layer may be performed with reference to contents described standard documents released earlier than the present document.

Communication System Applicable to the Present Disclosure

Although not limited thereto, various descriptions, functions, procedures, proposals, methods and/or operation flowcharts disclosed in the present disclosure are applicable to various fields requiring wireless communication/connection (e.g., 5G) between devices.

Hereinafter, it will be described in greater detail with reference to the drawings. In the following drawings/description, the same reference numerals may denote the same or corresponding hardware blocks, software blocks or functional blocks unless otherwise stated.

Communication System Applicable to the Present Disclosure

FIG.9is a view showing an example of a wireless device applicable to the present disclosure.

Referring toFIG.9, a first wireless device900aand a second wireless device900bmay transmit and receive radio signals through various radio access technologies (e.g., LTE or NR). Here, {the first wireless device900a, the second wireless device900b} may correspond to {the wireless device100x, the base station90} and/or {the wireless device100x, the wireless device100x}.

The first wireless device900amay include one or more processors902aand one or more memories904aand may further include one or more transceivers906aand/or one or more antennas908a. The processor902amay be configured to control the memory904aand/or the transceiver906aand to implement descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein. For example, the processor902amay process information in the memory904ato generate first information/signal and then transmit a radio signal including the first information/signal through the transceiver906a. In addition, the processor902amay receive a radio signal including second information/signal through the transceiver906aand then store information obtained from signal processing of the second information/signal in the memory904a. The memory904amay be coupled with the processor902a, and store a variety of information related to operation of the processor902a. For example, the memory904amay store software code including instructions for performing all or some of the processes controlled by the processor902aor performing the descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein. Here, the processor902aand the memory904amay be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE or NR). The transceiver906amay be coupled with the processor902ato transmit and/or receive radio signals through one or more antennas908a. The transceiver906amay include a transmitter and/or a receiver. The transceiver906amay be used interchangeably with a radio frequency (RF) unit. In the present disclosure, the wireless device may refer to a communication modem/circuit/chip.

The second wireless device900bmay include one or more processors902band one or more memories904band may further include one or more transceivers906band/or one or more antennas908b. The processor902bmay be configured to control the memory904band/or the transceiver906band to implement the descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein. For example, the processor902bmay process information in the memory904bto generate third information/signal and then transmit the third information/signal through the transceiver906b. In addition, the processor902bmay receive a radio signal including fourth information/signal through the transceiver906band then store information obtained from signal processing of the fourth information/signal in the memory904b. The memory904bmay be coupled with the processor902bto store a variety of information related to operation of the processor902b. For example, the memory904bmay store software code including instructions for performing all or some of the processes controlled by the processor902bor performing the descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein. Herein, the processor902band the memory904bmay be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE or NR). The transceiver906bmay be coupled with the processor902bto transmit and/or receive radio signals through one or more antennas908b. The transceiver906bmay include a transmitter and/or a receiver. The transceiver906bmay be used interchangeably with a radio frequency (RF) unit. In the present disclosure, the wireless device may refer to a communication modem/circuit/chip.

In addition, the structure of a wireless device applicable to the present disclosure is not limited toFIG.9, and may be configured in various forms. In particular, the present disclosure may be applied to a wireless device that performs an operation for transmitting and/or receiving a wireless signal, and is not limited to a specific form.

As an example, being a function supported based on a ProSe service, ProSe direct discovery may be a process for a user equipment (UE) to discover and recognize another UE adjacent to it based on NR, E-UTRA or WLAN. Herein, there may be two types of ProSe direct discovery: an open type and a restricted type. As an example, the open type may be a type of performing direct discovery without explicit permission for a UE to be discovered. On the other hand, the restricted type may be a type of performing direct discovery only based on explicit permission for a UE to be discovered.

As an example, ProSe direct discovery may be a service that is solely provided to use information on a specific application of a UE that is discovered. The UE may perform an additional operation through information that is obtained through ProSe direct discovery, and thus the service may be provided. In addition, as an example, as non-public safety UEs with a ProSe function, UEs having authority for ProSe direct discovery may perform the ProSe direct discovery function based on NR or E-UTRA in a serving PLMN. Herein, as an example, in case a non-public safety UE loses NR or E-UTRA coverage, the ProSe direct discovery function may not be supported, but the present disclosure is not limited thereto.

In addition, as an example, the ProSe direct discovery may be performed based on Model A or Model B but is not limited thereto. As an example, a UE, which has the ProSe function enabled in Model A, may play any one role of an announcing UE and a monitoring UE. As an example, the announcing UE may be a UE that announces specific information available in another UE that is adjacent and of which discovery is permitted. The monitoring UE may be a UE that monitors specific information announced by the announcing UE. Herein, the announcing UE may broadcast a discovery message during a preset search interval, and the monitoring UE may operate by confirming a message among broadcast messages and then implementing a process. That is, Model A may be a model in which an announcing UE delivers its presence and relevant information through broadcast and a search is performed when a neighbor monitoring UE is interested in the information.

As a concrete example,FIG.10is a view illustrating a method for performing ProSe direct discovery based on Model A that is applied in the present disclosure. Referring toFIG.10, a UE1010may perform service authentication based on ProSe functions1020and1030and a ProSe application server (ProSe App server)1040. Next, the UE1010, which is an announcing UE, may transmit a discovery request message to the ProSe function1020and then perform service authentication through the ProSe App server1040. Next, when authentication is completed, the UE1010may perform announcing in a broadcast way. In addition, when the UE1010performs monitoring, the UE1010may transmit a discovery request message to a monitoring UE through the ProSe function1020and then perform service authentication through the ProSe App server1040. Next, the UE1010may monitor an announced message. The UE1010may perform service matching based on announcing message monitoring and report matching information to the ProSe function1020and the ProSe App server1040.

On the other hand, Model B may be a model in which ProSe direct discovery is performed in the restricted discovery type as a discoverer UE transmits a restricted discovery message to a discoveree UE. More specifically, a discoverer UE may transmit a request including specific information to be discovered to a discoveree UE. Herein, the discoveree UE may deliver, to the discoverer UE, a response message, which includes relevant information, based on the request message received from the discoverer UE. That is, in Modell B, a discoverer UE may transmit a discovery request message for specific information to a specific discoveree UE and receive a response to the request message, and thus ProSe direct discovery may be performed. As an example, as the public safety discovery is a restricted discovery, a monitoring UE of Model A and a discoverer UE of Model B, which are described above, may need authorization to perform discovery in relation to a specific service, and the ProSe direct discovery may be performed based on this.

As a concrete example,FIG.11is a view illustrating a method for performing ProSe direct discovery based on Model B that is applied in the present disclosure. Referring toFIG.11, a UE1110may perform service authentication based on ProSe functions1120and1130and a ProSe application server (ProSe App server)1140. Next, the UE1010, which is a discoveree UE, may transmit a discovery request message to the ProSe function1120and then perform service authentication through a ProSe App server1140. Herein, the UE1110, which is a discoveree UE, may obtain a ProSe response code and a discovery query filter. The UE1110, which is a discoveree UE, may monitor the ProSe query code through PC5 and, when the ProSe query code is matched, announce a ProSe response code through PC5. Next, the UE1010, which is a discoverer UE, may transmit a discovery request message to the ProSe function1120and then perform service authentication through the ProSe App server1140. Herein, the UE1110, which is a discoverer UE, may obtain a discovery response filter, which is composed of a ProSe query code and a ProSe response code, and a ProSe application mask. Next, the UE1110, which is a discoverer UE, may announce the ProSe query code and complete discovery by monitoring a ProSe response code transmitted by a discoveree UE, thereby performing matching for a corresponding service. Next, the matching information may be reported to the ProSe function1120and the ProSe App server1140.

Based on what is described above, direct communication may be performed. In addition, as an example, a core network of a new communication system (e.g., 5G) may support at least one of ProSe direct discovery, ProSe direct communication, and ProSe UE-to-network relay. Herein, UEs operating based on a ProSe function may perform authentication. In addition, as an example, in UEs operating based on a ProSe function, pre-provisioning may be performed for ProSe direct discovery, ProSe direct communication, and ProSe UE-network relay, and the above-described service may be provided accordingly.

Hereinafter, a method for performing authentication for a ProSe UE-network relay service among the above-described ProSe services and for performing pre-provisioning will be described. As an example, in relation to authentication and provisioning for 5G ProSe UE-network relay, provisioning may be performed with a parameter and a policy with reference to Table 1 but is not limited thereto. In addition, a principle of applying a parameter for 5G ProSe UE-network relay with reference to Table 1 described above may be based on Table 2 and Table 3 but is not limited thereto.

TABLE 15.1.4.1 Policy/Parameter provisioning for 5G ProSe UE-to-Network RelayThe following information is provisioned in the UE in support of the UE assumingthe role of a ProSe UE-to-Network Relay:1) Authorisation policy for acting as a 5G ProSe Layer-3 and/or Layer-2 UE-to-Network Relay when “served by NG-RAN”:- PLMNs in which the UE is authorized to relay traffic for 5G ProSe Layer-3and/or Layer-2 Remote UEs.2) ProSe Relay Discovery policy/parameters for 5G ProSe UE-to-Network Relay:- Includes the parameters that enable the UE to perform 5G ProSe Relay Discoverywhen provisioned from the PCF in the ME or configured in the UICC:- 5G ProSe UE-to-Network Relay Discovery parameters (User Info ID, RelayService Code(s));- Default Destination Layer-2 ID(s) for sending and receiving initial signaling ofdiscovery messages;- For Layer 3 ProSe UE-to-Network Relay, the PDU Session parameters (PDUSession type, DNN, SSC Mode, S-NSSAI, Access Type Preference) to be used forthe relayed traffic for each ProSe Relay Service Code;- Includes security related content for 5G ProSe Relay Discovery for each ProSeRelay Service Code.Editor's note: Whether the security parameters can be provided by the PCF anddetails of security parameters will be determined by SA3 WG.NOTE 1: 5G ProSe Relay Discovery policy/parameters can be provided fromProSe Application Server to the 5G ProSe UE-to-Network Relay.3) For Layer 3 ProSe UE-to-Network Relay, QoS mapping(s):- Each QoS mapping entry includes:- a mapping between a 5QI value and a PQI value;- a PQI PDB adjustment factor, for the PC5 communication for the UE-to-NetworkRelay operation;- optional the Relay Service Code(s) associates with the QoS mapping entry.4) For 5G ProSe Layer 3 UE-to-Network Relay to relay Ethernet or Unstructuredtraffic from Remote UE by using IP type PDU Session,- Mapping of ProSe Service(s) to ProSe Application Server address information(consisting of IP address/FQDN and transport layer port number).The following information is provisioned in the UE in support of the UE assumingthe role of a Remote UE and thereby enabling the use of a ProSe UE-to-NetworkRelay:1) Authorisation policy for using a 5G ProSe Layer-3 and/or L ayer-2 UE-to-Network Relay:- Indicates whether the UE is authorised to use a 5G ProSe Layer-3 and/or Layer-2UE-to-Network Relay.2) Policy/parameters for 5G ProSe Relay Discovery:- Includes the parameters for 5G ProSe Relay Discovery and for enabling the UE toconnect to the 5G ProSe UE-to-Network Relay after discovery when provisionedfrom the PCF in the ME or configured in the UICC:- ProSe UE-to-Network Relay Discovery parameters (User Info ID, Relay ServiceCode(s));- Default Destination Layer-2 ID(s) for sending and receiving initial signaling ofdiscovery messages;- For 5G ProSe Layer 3 UE-to-Network Relay, the PDU Session parameters (PDUSession type, DNN, SSC Mode, S-NSSAI, Access Type Preference) to be used forthe relayed traffic for each ProSe Relay Service Code;- Includes security related content for ProSe Relay Discovery for each ProSe RelayService Codes.Editor's note: Whether the security parameters can be provided by the PCF anddetails of security parameters will be determined by SA3 WG.NOTE 2: ProSe Relay Discovery policy/parameters can be provided from ProSeApplication Server to the Remote UE.The following information is provisioned in the UE in support of the UE assumingthe role of a 5G ProSe UE-to-Network Relay as well as in the UE in support of theUE assuming the role of a 5G ProSe Remote UE and thereby enabling the use of a 5GProSe UE-to-Network Relay:1) Radio parameters for 5G ProSe Relay Discovery when the UE is not “served byNG-RAN ”:- Includes the radio parameters NR PC5 with Geographical Area(s) and anindication of whether they are “operator managed” or “non-operator managed”. TheUE uses the radio parameters to perform 5G ProSe Direct Discovery over PC5reference point when “not served by NG-RAN” only if the UE can reliably locateitself in the corresponding Geographical Area. Otherwise, the UE is not authorized totransmit.2) Radio parameters for 5G ProSe Relay Communication when the UE is not“served by NG-RAN”:- Includes the radio parameters NR PC5 with Geographical Area(s) and anindication of whether they are “operator managed” or “non-operator managed”. TheUE uses the radio parameters to perform 5G ProSe Direct Communication over PC5reference point when “not served by NG-RAN” only if the UE can reliably locateitself in the corresponding Geographical Area. Otherwise, the UE is not authorized totransmit.

FIG.12is a view illustrating a method for performing ProSe communication based on UE-network relay that is applied to the present disclosure. Referring toFIG.12, a relay UE1220may be registered to a network. As an example, the relay UE1220may be a layer-3 UE-to-network relay but will be referred to as relay UE1220below for convenience of explanation. Herein, after being registered to a network, the relay UE1220may establish a PDU session for providing a relay for a remote UE1210or may modify a current PDU session for providing a relay. The relay UE1220may use a PDU session for relay traffic for the remote UE1210. In addition, as an example, a serving PLMN of the relay UE1220and a PLMN to which the remote UE1210is registered may be identical with or different from each other and may not be limited to a specific form.

More particularly, referring toFIG.12, service authentication and provisioning for the relay UE1220may be performed. In addition, as an example, service authentication and provisioning for the remote UE1210may also be performed. Herein, the relay UE1220may establish or modify a PDU session for relay. Next, the remote UE1210may perform a discovery procedure for the relay UE1220. Herein, the remote UE1210may recognize an accessible service based on the relay UE1220through the discovery procedure. Next, the remote UE1210and the relay UE may establish a connection for unicast mode communication. In case there is no PDU session associated with a relay service code or a new PDU session for relay is required, the relay UE1220may start a procedure of establishing a new PDU session before completely establishing a PC5 connection. In addition, as an example, the relay UE1220may determine a PDU session type for relay.

Herein, based on the PDU session type for relay, the relay UE1220may perform a relay function in a corresponding layer. Next, an IP address and a prefix may be allocated to the remote UE1210and the relay UE1220. The remote UE1210may deliver a PC5 QoS rule to the relay UE1220, and the relay UE1220may generate a packet filter used in a Uu interface based on the PC5 QoS rule. Next, the relay UE1220may perform a PDU session change and set a new QoS flow or combine traffic to an existing QoS flow. Next, the remote UE1210may perform uplink and downlink relay based on the relay UE1220. Herein, in case downlink traffic is forwarded, the PC5 QoS rule may be applied to a downlink packet for PC5 QoS flow. In addition, as an example, in case uplink traffic is forwarded, a 5G QoS rule may be applied to an uplink packet for Uu QoS flow. Next, for a PDU session associated with relay, the relay UE1220may deliver a remote UE report including a remote UE ID and remote UE information to the SMF1250. Herein, the remote UE ID is an ID for identifying a remote UE and may be an identifier of the remote UE that successfully performs connection to the relay UE1220. Based on what is described above, the remote UE1210may perform traffic exchange with a network through the relay UE1220. Herein, the core network may perform authentication for a UE that performs connection to the core network.

In case a remote UE is connected to a 5G core network based on a relay UE, the remote UE and the 5G core network may perform primary authentication. Next, a remote UE connected to the 5G core network may request to generate a PDU session for access to a specific data network based on a relay UE. Herein, secondary authentication may be performed between the remote UE and the data network, which is the same as described above.

As an example, based on a predetermined condition, secondary authentication may be revoked or discarded according to a determination of a 5G core network or a data network. Herein, also in a previous wireless communication system, after a UE performs secondary authentication with a data network, the secondary authentication may be revoked based on a predetermined condition. As an example, in case secondary authentication is revoked, a PDU session, which a UE generates for access to a specific data network, may be canceled, and a procedure for this may be performed.

However, in consideration of a ProSe relay structure of a remote UE and a relay UE, a plurality of remote UEs may be connected to a single relay UE. Accordingly, as in a previous wireless communication system, in case second authentication is revoked so that a PDU session generated by a remote UE in a data network through a relay UE is canceled, other remote UEs connected to the same relay UE may not be provided with a service. That is, as secondary authentication is revoked based on a specific remote UE among a plurality of remote UEs connected to a single relay UE, when a PDU session of the relay UE is canceled, there may be a problem with providing a service of another remote UE, a procedure for this may be necessary, and a concrete method for this will be described below.

As an example, in case a remote UE is connected to a core network through a relay UE based on ProSe relay, the remote UE may perform a primary authentication procedure with the core network through the relay UE. After primary authentication, the remote UE may request to generate a PDU session for access to a specific data network based on ProSe relay and perform secondary authentication with the data network, which is the same as described above.

Herein, secondary authentication between a remote UE and a data network may be revoked and discarded based on a predetermined condition. As an example, a predetermined condition for the revocation and discarding of secondary authentication may be a certificate renewal, revocation, expiration of validity, and other causes and may not be limited to a specific embodiment. Hereinafter will be described a method for solving the problem of other remote UEs connected to a relay UE in failing to receive a service, in case a PDU session generated by a remote UE in a data network through the relay UE based on an operation of revoking secondary authentication in a previous wireless communication system.

FIG.13is a view illustrating a method for performing secondary authentication after setting PC5 link according to an embodiment of the present disclosure.

Referring toFIG.13, a remote UE1310and a relay UE1320may perform pre-authentication from each network so as to operate in a ProSe UE-to-network relay system. Herein, each of the remote UE1310and the relay UE1320may receive information considering a ProSe relay operation. Information considering a ProSe relay operation may include information on an authentication scheme, information necessary for direct discovery between UEs, and other types of information, but is not limited to a specific form.

Next, the relay UE1320may generate a PDU session in advance which is capable of providing a relay service when the remote UE1310is being connected. The remote UE1310may perform a discovery procedure for the relay UE1320based on information considering a ProSe relay operation. As an example, the remote UE1310may perform the discovery of the relay UE1320based on information considering a ProSe relay operation and discover the relay UE1320based on at least one ofFIG.10andFIG.11described above.

Next, the remote UE1310may perform a procedure of establishing a connection for direct communication with the relay UE1320. Herein, the remote UE1310may deliver an ID of the remote UE (e.g. SUCI) to the relay UE1320. The relay UE1320may request AMF1340of the relay UE to authenticate the remote UE1310based on the received ID of the remote UE. Based on what is described above, a network may perform primary authentication with the remote UE1310through the relay UE1320.

Next, based on a result of the primary authentication, the remote UE1310and the relay UE1320may perform a direct security mode command procedure between the remote UE1310and the relay UE1320and configure a security channel in a PC5 interface.

In case there is no PDU session satisfying a PC5 connection requirement of the remote UE1310, the relay UE1320may perform a procedure for establishing anew PDU session or a procedure for modifying a PDU session. As an example, the PC5 connection requirement may be set by considering at least one of S-NSSAI, DNN, QoS, and UP security enabled states, but is not limited to the above-described embodiment.

Next, the relay UE1320may transmit a remote UE report message to the SMF1350. Herein, the remote UE report message may include at least one of a remote UE ID and remote UE information. As an example, the remote UE ID may be identification information of a remote UE user, and the remote UE information may be information used for identifying a remote UE in 5GC. Specifically, when a PDU session is an IP type, remote UE information may be IP information of a remote UE. On the other hand, when a PDU session is an ethernet type, remote UE information may be an MAC address of a remote UE. The SMF1350may store a remote UE ID and remote UE information in a context for a PDU session that is used for relay. Next, a PDU session of a relay UE, which is to be used by the remote UE1310, may be completely configured. The remote UE1310may perform secondary authentication of a data network that will be connected with the remote UE1310according to a network setting.

Next, the relay UE1320may transmit an EAP message to the remote UE1310through PC5 signaling and receive an EAP message from the remote UE1310through PC5 signaling. The relay UE1320may transmit a PDU session authentication completion message, which includes an ID of the remote UE and an EAP message received the remote UE, to the SMF1350. The SMF1350may transmit an EAP message to data network-authentication, authorization and accounting (DN-AAA)1360. Next, the DN-AAA1360and the remote UE1310may exchange EAP messages. Herein, when authentication is successful, the DN-AAA1360may transmit an EAP success message to the SMF1350, and the remote UE1310may perform communication through the relay UE1320. On the other hand, when authentication fails, the DN-AAA1360may transmit an EAP failure message to the SMF1350. The SMF1350may transmit a remote UE release command message including a remote UE ID to the relay UE1320. The relay UE1320may release a PC5 link with the remote UE and transmit an ACK response for the remote UE release command message to the SMF1350.

FIG.14is a view illustrating a method for a remote UE to perform secondary authentication and revoke secondary authentication through a relay UE according to an embodiment of the present disclosure.

Referring toFIG.14, a remote UE1410and a relay UE1420may perform pre-authentication from each network so as to operate in a ProSe UE-to-network relay system.

Herein, each of the remote UE1410and the relay UE1420may receive information considering a ProSe relay operation. As an example, information considering a ProSe relay operation may include information on an authentication scheme, information necessary for direct discovery between UEs, and other types of information, but is not limited to a specific form.

Next, the relay UE1420may generate a PDU session in advance which is capable of providing a relay service when the remote UE1410is being connected. As an example, the remote UE1410may perform the discovery of the relay UE1420based on information considering a ProSe relay operation and discover the relay UE1420based on at least one ofFIG.10andFIG.11described above.

Next, the remote UE1410may transmit a connection request (direct communication request) message, which includes a remote UE ID and a relay service code (RSC), to the relay UE1420. The relay UE1420may request AMF/SEAF1430of the relay UE to authenticate the remote UE1410based on the received ID of the remote UE. Thus, a network may perform primary authentication with the remote UE1410.

Next, based on a result of the primary authentication, the remote UE1410and the relay UE1420may perform a direct security mode command procedure between the remote UE1410and the relay UE1420and configure a security channel in a PC5 interface. As a response to the direct communication request message, the relay UE1420may transmit a direct communication accept message to the remote UE1410and complete a PC5 channel setting.

Herein, the relay UE1420may determine PDU session parameters that are mapped with the received RSC of the remote UE. As an example, a PDU session parameter may include at least one of a PDU session type, DNN, an SSC mode, S-NSSAL, and an access type preference, but may not be limited thereto. As an example, in case a PDU session, which the relay UE1420generates for a relay service in advance, satisfies a PDU session parameter condition that is mapped with an RSC of the remote UE1410, the relay UE1420may use an existing PDU session as it is.

On the other hand, in case a PDU session, which the relay UE1420generates for a relay service in advance, does not satisfy a PDU session parameter condition that is mapped with an RSC of the remote UE1410, the relay UE1420may request to generate a new PDU session or request to modify an existing PDU session. Next, the relay UE1420may transmit a remote UE report message to the SMF1440. Herein, the remote UE report message may include at least one of a remote UE ID and remote UE information. As an example, the remote UE ID may be identification information of a remote UE user, and the remote UE information may be information used for identifying a remote UE in 5GC. Specifically, when a PDU session is an IP type, remote UE information may be IP information of a remote UE. On the other hand, when a PDU session is an ethernet type, remote UE information may be an MAC address of a remote UE. The SMF1440may store a remote UE ID and remote UE information in a context for a PDU session that is used for relay. Next, a PDU session of a relay UE, which is to be used by the remote UE1410, may be completely configured. The remote UE1410may perform secondary authentication of a data network that will be connected with the remote UE1410according to a network setting, and thus may perform communication with a data network via the relay UE1420.

Herein, secondary authentication may be revoked and discarded. As an example, secondary authentication may be revoked and discarded based on a predetermined condition. Specifically, secondary authentication may be revoked and discarded based on the expiration of authentication when the authentication needs to be renewed. As another example, secondary authentication may be revoked and discarded when a policy about the authentication is modified. As another example, secondary authentication may be revoked and discarded based on a configuration change of a network and a data network but may not be limited the above-described condition. Herein, the revocation and discarding of secondary authentication may be determined by the SMF1440of a network. As another example, the revocation and discarding of secondary authentication may also be determined by the DN-AAA1460and is not limited to a specific embodiment.

As an example, in case the revocation and discarding of secondary authentication for a specific remote UE is determined by the DN-AAA1460, the DN-AAA1460may transmit, to the SMF1440, an authentication revocation request message for the remote UE1410. Herein, the authentication revocation request message may be determined according to an interface between the SMF1440and the external DN-AAA1460and a protocol. The authentication revocation request message may include a remote UE ID (e.g. GPSI, IP address, MAC address, etc) for indicating the specific remote UE1410, based on which secondary authentication may be revoked and discarded.

Herein, as an example, as described above, since a plurality of remote UEs may be connected to the relay UE1420, when secondary authentication is revoked and discarded based on a specific remote UE, a PDU session of the relay UE needs to be maintained for other remote UEs.

FIG.15is a view illustrating a method for maintaining a PDU session based on secondary authentication revocation and discarding according to an embodiment of the present disclosure. Referring toFIG.15, an SMF1540may check at least one of remote UEs1510using a same PDU session. That is, the SMF1540may check whether or not there is a remote UE other than a specific remote UE1510, of which the secondary authentication is to be revoked and discarded, in a same PDU session of a relay UE.

Specifically, the SMF1540may receive, from the DN-AAA1560, a command to revoke secondary authentication for a specific remote UE. As another example, the SMF1540may directly revoke and discard secondary authentication for the specific remote UE1510based on a setting. As an example, when a secondary authentication revocation and discarding condition is satisfied, the SMF1540may check whether or not there is any other remote UE than the remote UE1510in a PDU session of a relay UE that the remote UE is using. That is, the SMF1540may determine whether or not another remote UE is being shared and used in the PDU session. As an example, as described above, a remote UE ID and remote UE information are stored in a context for a PDU session, and the SMF1540may determine whether or not there is another remote UE in the PDU session based on the above-described information.

Herein, in case another remote UE is not additionally present in a PDU session of a relay UE in which a remote UE requested to revoke secondary authentication is being used, the SMF1540may transmit a PDU session release request message of the relay UE1520to the relay UE1520. Herein, the PDU session release request message may include a release cause value, and a release cause may order secondary authentication of a remote UE to be revoked. In addition, as an example, the PDU session release request message may include information for ordering the relay UE1520to release a PC5 channel to the remote UE1510. In order to release the PC5 channel connected to the remote UE1510based on the PDU session release request message received from the SMF, the relay UE1520may transmit a PC5 channel release command message to the remote UE1510. Herein, the PC5 channel release command message may include a release cause value. A release cause value may order the remote UE to revoke secondary authentication. The remote UE1510may perform a PC5 channel release operation based on the PC5 channel release command message and transmit, to the relay UE1520, a PC5 release complete message as PC5 release result information. Next, the relay UE1520may complete PC5 channel release and transmit the requested PDU session release complete message to the SMF1540.

That is, in case another remote UE is not additionally present in a PDU session of a relay UE in which a remote UE requested to revoke secondary authentication is being used, the SMF1540may order the relay UE1520to release a PC5 channel and to release a PDU session through a single message.

However, as an example, a PDU session of a relay UE may be present by default. In addition, as another example, a PDU session of a relay UE needs to exist based on another request or any other cause, and in consideration of this, PDU session release and PC5 channel release may be ordered to the relay UE1520through respective messages.

FIG.16is a view illustrating a method for maintaining a PDU session based on secondary authentication revocation and discarding according to an embodiment of the present disclosure. Referring toFIG.16, an SMF1640may check at least one of remote UEs1610using a same PDU session. That is, the SMF1640may check whether or not there is a remote UE other than a specific remote UE1610, of which the secondary authentication is to be revoked and discarded.

Specifically, the SMF1640may receive, from the DN-AAA1660, a command to revoke secondary authentication for a specific remote UE. As another example, the SMF1640may directly revoke and discard secondary authentication for the specific remote UE1610based on a setting. As an example, when a secondary authentication revocation and discarding condition is satisfied, the SMF1640may check whether or not there is any other remote UE than the remote UE1610in a PDU session of a relay UE that the remote UE is using. That is, the SMF1640may determine whether or not another remote UE is being shared and used in the PDU session. As an example, as described above, a remote UE ID and remote UE information are stored in a context for a PDU session, and the SMF1640may determine whether or not there is another remote UE in the PDU session based on the above-described information.

Herein, in case another remote UE is not additionally present in a PDU session of a relay UE in which a remote UE requested to revoke secondary authentication is being used, the SMF1640may transmit, to the relay UE1620, a PC5 channel release request message for the remote UE1610, of which the secondary authentication is revoked. Herein, the PC5 channel release request message may be an NAS message. As an example, the PC5 channel release request message may include at least one of a remote UE ID and a release cause in order to enable the relay UE1620to identify the remote UE1610.

The relay UE1620may transmit a PC5 channel release command message to the remote UE1610that corresponds to the remote UE ID delivered from the SMF1640. Herein, the PC5 channel release command message may include a release cause value. A release cause may order the remote UE to revoke secondary authentication. The remote UE1610may perform a PC5 channel release operation based on the PC5 channel release command received from the relay UE1620. Next, the remote UE1610may notify the completion of the PC5 channel release by transmitting a PC5 release complete message to the relay UE1620. Next, the relay UE1620may notify to the SMF1640that the remote UE1610and the PC5 channel are normally released. As an example, based on a remote UE report, the relay UE1620may indicate to the SMF1640that PC5 channel release is normally completed. As another example, as a response to the above-described remote UE PC5 release request, the relay UE1620may indicate, through a remote UE PC5 release response message, that PC5 channel release is normally completed.

Next, the SMF1640may check whether or not there is another remote UE using the PDU session. Herein, in case there is no other UE using the PDU session, the SMF1640may perform an operation of releasing the PDU session with the relay UE1620. That is, based on another message, the SMF1640may order the relay UE1620to release a PC5 channel and the PDU session.

Herein, in case the relay UE1620receives a PDU session release request from the SMF1640on the ground that there is no other remote UE using the PDU session, the relay UE1620may perform the release of the PDU session. However, in case an access request of another remote UE occurs before the relay UE1620performs the operation of releasing the PDU session, the relay UE1620may not implement the PDU session release request of the SMF1640but maintain and reuse the PDU session. That is, even when the relay UE1620receives a PDU session release request from the SMF1640, if there is another remote UE in a corresponding PDU session, the relay UE1620may reject the request of the SMF1640and maintain the PDU session.

FIG.17is a view illustrating a method for maintaining a PDU session according to an embodiment of the present disclosure.

Referring toFIG.17, a relay UE1720may check at least one of remote UEs1710using a same PDU session. That is, the relay UE1720may check whether or not there is a remote UE other than a specific remote UE1710, of which the secondary authentication is to be revoked and discarded, in a PDU session of the relay UE.

Specifically, the SMF1740may receive, from the DN-AAA1760, a command to revoke secondary authentication for a specific remote UE. As another example, the SMF1740may directly revoke and discard secondary authentication for the specific remote UE1710based on a setting. As an example, in case a secondary authentication revocation and discarding condition is satisfied, the SMF1740may transmit, to the relay UE1720, a PC5 channel release request message for the remote UE1710, of which the secondary authentication is revoked.

Herein, the PC5 channel release request message may be an NAS message. As an example, the PC5 channel release request message may include at least one of a remote UE ID and a release cause in order to enable the relay UE1720to identify the remote UE1710.

The relay UE1720may transmit a PC5 channel release command message to the remote UE1710that corresponds to the remote UE ID delivered from the SMF1740. Herein, the PC5 channel release command message may include a release cause value. A release cause may order the remote UE to revoke secondary authentication. The remote UE1710may perform a PC5 channel release operation based on the PC5 channel release command received from the relay UE1720. Next, the remote UE1710may notify the completion of the PC5 channel release by transmitting a PC5 release complete message to the relay UE1720. Next, the relay UE1720may notify the SMF1740that the remote UE1710and the PC5 channel release are normally completed. As an example, based on a remote UE report, the relay UE1720may indicate to the SMF1740that PC5 channel release is normally completed. As another example, as a response to the above-described remote UE PC5 release request, the relay UE1720may indicate, through a remote UE PC5 release response message, that PC5 channel release is normally completed.

Herein, the relay UE1720may determine whether or not there is another additional remote UE using the PDU session. In case it is determined that there is no other remote UE than a remote UE in the PDU session, of which the secondary authentication is revoked and discarded, the relay UE1720may start a procedure for releasing the PDU session. That is, based on a remote UE release command from the SMF1740, the relay UE1720may release the remote UE1710and a PC5 channel and determine whether or not to release the PDU session. That is, when there is no other remote UE using the PDU session, the relay UE1720may transmit a PDU session release request for releasing the PDU session to the SMF1740. However, as an example, in case the relay UE1720requests the SMF1740to release the PDU session after determining that there is no other remote UE using the PDU session, the SMF1740may reject the release request by a separate policy (local configuration) and maintain the PDU session for a next relay service, but the present disclosure is not limited thereto.

On the other hand, in case the relay UE1720determines that the PDU session is additionally used by another remote UE, the relay UE1720may not release but maintain the PDU session.

FIG.18is a view illustrating a method for performing a secondary authentication revocation procedure based on SMF according to an embodiment of the present disclosure.

Referring toFIG.18, secondary authentication revocation for a first remote UE may be determined (S1810). As an example, the first remote UE may be a specific remote UE among a plurality of remote UEs. The secondary authentication revocation for the first remote UE may be determined based on a predetermined condition and is not limited to a specific cause. Herein, as an example, the secondary authentication revocation for the first remote UE may be determined by a SMF.

As a concrete example, in case the first remote UE leaves a communication-permitted zone, secondary authentication may be revoked. As another example, in case an access UPF for transmitting user plane data is reconfigured, secondary authentication may be revoked. As another example, in case RAN fails to allocate a PDU session resource in a mobility situation, secondary authentication may be revoked.

As another example, the secondary authentication revocation for the first remote UE may be determined by a request of DN-AAA. As a concrete example, in case the validity period of qualification used for secondary authentication between an external DN-AAA and the first remote UE has expired, a revocation request for revoking the secondary authentication may be executed. In addition, as an example, a qualification operating regulation of a DN-AAA is modified, a secondary authentication revocation request may be executed, but may not limited thereto.

Next, PDU session and PC5 channel release may be performed based on secondary authentication revocation of a remote UE. Herein, a subject determining the number of remote UEs using a PDU session of a same relay UE may be different. As an example, the number of remote UEs using a PDU session of a same relay UE may be determined by a SMF. That is, based on determination of secondary authentication revocation for the first remote UE, the SMF may determine whether or not only the first remote UE uses a same PDU session of a relay UE (S1820). The SMF may check whether or not another remote UE additionally uses the PDU session of the relay UE that the first remote UE currently uses, for which the secondary authentication is revoked. Herein, since the SMF stores information on a remote UE and information on a relay UE, which are provided when the remote UE accesses a PDU session through a relay UE, the SMF may check a remote UE that uses a same PDU session of the relay UE. Herein, in case there is one remote UE that uses a PDU session of a relay UE (S1820), the SMF may transmit, to the relay UE, a PDU session release request message for requesting to release a PDU session and a PC5 channel that are used in a relay service (S1830). Herein, the PDU session release request message may be an NAS message. That is, the SMF may request the relay UE to release a PDU session and to release a PC5 channel at the same time. The PDU session release request message may include a release cause value. The release cause value may indicate revocation of secondary authentication for a remote UE. Next, the relay UE may perform a PC5 channel release procedure with the first remote UE connected to the relay UE (S1840). Herein, the relay UE may transmit a PC5 channel release request message to the first remote UE. The PC5 channel release request message may include the release cause value delivered from the SMF. In case PC5 channel release between the first remote UE and the relay UE is completed, the relay UE may complete a PDU session release operation and report a PDU session release complete state to the SMF (S1850).

On the other hand, in case at least one remote UE other than the first UE is being used in the same PDU session of the relay UE (S1820), the SMF may transmit two SM NAS messages to the relay UE. That is, the SMF may make a PC5 channel release request and a release request for the PDU session respectively. As an example, the SMF may transmit a PC5 channel release request message to the relay UE in order to release a PC5 channel with the first remote UE for which secondary authentication is revoked (S1860). Herein, the message that the SMF sends to the relay UE may be a NAS message. That is, the SMF may transmit a remote UE release request message to the relay UE, and the PC5 channel release request message may be as shown in Table 4 below. As an example, a remote UE release request may include remote UE ID information for specifying a remote UE and a release cause value. As an example, the release cause value may indicate revocation of secondary authentication.

Next, the relay UE may perform a procedure of releasing the PC5 channel with the first remote UE, which is requested from the SMF (S1870). Herein, the PC5 channel release request message may include the release cause value delivered from the SMF. In case PC5 channel release between the remote UE and the relay UE is completed, the relay UE may report a release result for the PC5 channel with the remote UE to the SMF through a NAS message, which is ordered (S1880). Next, the SMF may determine whether to maintain or release a PDU session of the relay UE for a relay service. As an example, in case there is no other remote UE using the PDU session or no further reuse is necessary, the SMF may additionally transmit a release request for the PDU session to the relay UE. Herein, the PDU session release request message may be a SM NAS message. As an example, in case the SMF requests the relay UE to release the PDU session, the relay UE may perform a release operation or reject it based on a predetermined condition. As an example, although the relay UE receives a release request from the SMF, in case another remote UE, which satisfies the condition for using the PDU session, makes a request for accessing the PDU session, the relay UE may reject the PDU session release request of the SMF and keep using the PDU session for the relay service of the another remote UE.

FIG.19is a view illustrating a method for performing a secondary authentication revocation procedure based on SMF according to an embodiment of the present disclosure.

Referring toFIG.19, secondary authentication revocation for a first remote UE may be determined (S1910). As an example, the first remote UE may be a specific remote UE among a plurality of remote UEs. The secondary authentication revocation for the first remote UE may be determined based on a predetermined condition and is not limited to a specific cause. Herein, as an example, the secondary authentication revocation for the first remote UE may be determined by a SMF.

As a concrete example, in case the first remote UE leaves a communication-permitted zone, secondary authentication may be revoked. As another example, in case an access UPF for transmitting user plane data is reconfigured, secondary authentication may be revoked. As another example, in case RAN fails to allocate a PDU session resource in a mobility situation, secondary authentication may be revoked.

As another example, the secondary authentication revocation for the first remote UE may be determined by a request of DN-AAA. As a concrete example, in case the validity period of qualification used for secondary authentication between an external DN-AAA and the first remote UE has expired, a revocation request for revoking the secondary authentication may be executed. In addition, as an example, a qualification operating regulation of a DN-AAA is modified, a secondary authentication revocation request may be executed, but may not limited thereto.

Next, PDU session and PC5 channel release may be performed based on secondary authentication revocation of a remote UE. Herein, a subject determining the number of remote UEs using a PDU session of a same relay UE may be different. As an example, the number of remote UEs using a PDU session of a same relay UE may be determined by a SMF. That is, based on determination of secondary authentication revocation for the first remote UE, the SMF may determine whether or not only the first remote UE uses a same PDU session of a relay UE. The SMF may check whether or not another remote UE additionally uses the PDU session of the relay UE that the first remote UE currently uses, for which the secondary authentication is revoked. Herein, since the SMF stores information on a remote UE and information on a relay UE, which are provided when the remote UE accesses a PDU session through a relay UE, the SMF may check a remote UE that uses a same PDU session of the relay UE. Herein, the SMF may transmit two SM NAS messages to the relay UE. That is, the SMF may make a PC5 channel release request and a release request for the PDU session respectively. As an example, the SMF may transmit a PC5 channel release request message to the relay UE in order to release a PC5 channel with the first remote UE for which secondary authentication is revoked (S1920). Herein, the message that the SMF sends to the relay UE may be a NAS message. That is, the SMF may transmit a remote UE release request message to the relay UE, and the PC5 channel release request message may be described as in Table 4 above. As an example, a remote UE release request may include remote UE ID information for specifying a remote UE and a release cause value. As an example, the release cause value may indicate revocation of secondary authentication.

Next, the relay UE may perform a procedure of releasing a PC5 channel with the first remote UE, which is requested from the SMF (S1930). Herein, the PC5 channel release request message may include the release cause value delivered from the SMF. In case PC5 channel release between the remote UE and the relay UE is completed, the relay UE may report a release result for the PC5 channel with the remote UE to the SMF through a NAS message, which is ordered (S1940). Next, the SMF may determine whether to maintain or release a PDU session of the relay UE for a relay service. That is, the SMF may determine whether or not any other remote UE than the first remote UE is using the same PDU session. As an example, in case there is no other remote UE using the PDU session or no further reuse is necessary (S1950), the SMF may additionally transmit a release request for the PDU session to the relay UE (S1960). Herein, the PDU session release request message may be a SM NAS message. As an example, in case the SMF requests the relay UE to release the PDU session, the relay UE may perform a release operation or reject it based on a predetermined condition. As an example, although the relay UE receives a release request from the SMF, in case another remote UE, which satisfies the condition for using the PDU session, makes a request for accessing the PDU session, the relay UE may reject the PDU session release request of the SMF and keep using the PDU session for the relay service of the another remote UE.

On the other hand, in case there is another remote UE than the first remote UE in the same PDU session, the SMF may maintain the PDU session, not transmitting a message for releasing the PDU session (S1970).

FIG.20is a view illustrating a method for performing a secondary authentication revocation procedure based on SMF according to an embodiment of the present disclosure.

Referring toFIG.20, secondary authentication revocation for a first remote UE may be determined (S2010). As an example, the first remote UE may be a specific remote UE among a plurality of remote UEs. The secondary authentication revocation for the first remote UE may be determined based on a predetermined condition and is not limited to a specific cause. Herein, as an example, the secondary authentication revocation for the first remote UE may be determined by a SMF.

As a concrete example, in case the first remote UE leaves a communication-permitted zone, secondary authentication may be revoked. As another example, in case an access UPF for transmitting user plane data is reconfigured, secondary authentication may be revoked. As another example, in case RAN fails to allocate a PDU session resource in a mobility situation, secondary authentication may be revoked.

As another example, the secondary authentication revocation for the first remote UE may be determined by a request of DN-AAA. As a concrete example, in case the validity period of qualification used for secondary authentication between an external DN-AAA and the first remote UE has expired, a revocation request for revoking the secondary authentication may be executed. In addition, as an example, a qualification operating regulation of a DN-AAA is modified, a secondary authentication revocation request may be executed, but may not limited thereto.

Next, PDU session and PC5 channel release may be performed based on secondary authentication revocation of a remote UE. Herein, a subject determining the number of remote UEs using a PDU session of a same relay UE may be different. As an example, the number of remote UEs using a PDU session of a same relay UE may be determined by the relay UE. That is, based on determination of secondary authentication revocation for the first remote UE, the relay UE may determine whether or not only the first remote UE uses a same PDU session of the relay UE. Herein, the SMF may request the relay UE only to release a PC5 channel with the first remote UE for which secondary authentication is revoked (S2020). Herein, a message sent from the SMF to the relay UE may be described as in Table 4 above. A PC5 channel release request message may include a remote UE ID for specifying the remote UE and a release cause value. Herein, the release cause may indicate the revocation of secondary authentication for the remote UE. Next, the relay UE may perform a procedure of releasing the PC5 channel with the first remote UE, which is requested from the SMF (S2030). Herein, the PC5 channel release request message may include the release cause value delivered from the SMF. In case PC5 channel release between the remote UE and the relay UE is completed, the relay UE may report a release result for the PC5 channel with the remote UE to the SMF through a NAS message, which is ordered (S2040). Next, the relay UE may determine whether to maintain or release a PDU session of the relay UE for a relay service. As an example, in case no other remote UE than the first remote UE uses the PDU session or no further reuse is necessary (S2050), the relay UE may request the SMF to release the PDU session (S2060). In case the relay requests to release the PDU session, the SMF may perform a PDU session release operation or reject the request. As an example, in case the SMF is basically set to always maintain a default PDU session for a relay service, the SMF may reject the PDU session release request of the relay UE but may not be limited thereto.

On the other hand, in case another remote UE different from the first remote UE additionally uses the PDU session (S2050), the relay UE may maintain the PDU session of an existing relay UE and thus ensure a relay service of the another remote UE (S2070).

FIG.21is a flowchart illustrating a method for revoking secondary authentication according to an embodiment of the present disclosure.

Referring toFIG.21, a network may determine authentication revocation of a first remote UE (S2110). Herein, the network may determine whether or not another remote UE uses a PDU session of a relay UE that the first remote UE uses (S2120). Herein, in case no other remote UE uses the PDU session of the relay UE which is used by the first remote UE (S2130), the network may transmit a request for releasing the PDU session of the relay UE to the relay UE (S2140). On the other hand, in case another remote UE uses the PDU session of the relay UE which is used by the first remote UE (S2130), the network may transmit a request for releasing a PC5 link of the first remote UE to the relay UE (S2150).

Herein, as an example, the authentication revocation of the first remote UE may be determined by the SMF or a DN-AAA, as described above. In case the authentication revocation of the first remote UE is determined based on the DN-AAA, the SMF may receive an authentication revocation request message for the first remote UE from the DN-AAA. Next, the SMF may determine the authentication revocation of the first remote UE.

In addition, as an example, the network may perform authentication for at least one remote UE through a relay UE. Herein, the network may obtain identification information and relevant information for at least one or more remote UEs respectively through the relay UE. Thus, the network may determine whether or not there is any other remote UE than the first remote UE which uses a PDU session of the relay UE.

In addition, as an example, in case the network transmits a PDU session release request of the relay UE, the PDU session release request of the relay UE may include a release cause value, and the release cause value may indicate authentication revocation for the first remote UE. The relay UE may perform a PC5 release procedure with the first remote UE based on the PDU session release request of the relay UE, release the PDU session and report the completion of the PDU session to the network.

On the other hand, in case the network transmits a PC5 link release request of the first remote UE to the relay UE, the PC5 link release request of the first remote UE may include identification information of the first remote UE and a release cause value indicating the authentication revocation of the first remote UE. The relay UE may perform a procedure of releasing a PC5 link with the first remote UE based on the identification information of the first remote UE and report the completion of releasing the PC5 link with the first remote UE to the network, as described above.

As the examples of the proposal method described above may also be included in one of the implementation methods of the present disclosure, it is an obvious fact that they may be considered as a type of proposal methods. In addition, the proposal methods described above may be implemented individually or in a combination (or merger) of some of them. A rule may be defined so that information on whether or not to apply the proposal methods (or information on the rules of the proposal methods) is notified from a base station to a terminal through a predefined signal (e.g., a physical layer signal or an upper layer signal).

The present disclosure may be embodied in other specific forms without departing from the technical ideas and essential features described in the present disclosure. Therefore, the above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the present disclosure should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the present disclosure are included in the scope of the present disclosure. In addition, claims having no explicit citation relationship in the claims may be combined to form an embodiment or to be included as a new claim by amendment after filing.