WO2021034126A1 - Communication related to layer 2 relay - Google Patents

Abstract

A disclosure of the present specification provides a method for performing communication related to a layer 2 relay by a base station. The method may comprise the steps of: receiving downlink data from a UPF node to a remote UE; checking whether both the remote UE and a relay UE connected to the remote UE on the basis of the layer 2 relay are in an RRC_CONNECTED state; and transmitting a paging message to the relay UE.

Description

Communication related to layer 2 relay

The present specification relates to mobile communication.

Thanks to the success of LTE (long term evolution)/LTE-Advanced (LTE-A) for 4G mobile communication, interest in the next generation, that is, 5G (so-called 5G) mobile communication, is also increasing, and research is continuing. .

For the fifth generation (so-called 5G) mobile communication, a new radio access technology (New RAT or NR) has been studied.

　5th generation mobile communication defined by the International Telecommunication Union (ITU) refers to providing a maximum 　20Gbps data transmission speed and a sensible transmission speed of at least 　100Mbps　 or more anywhere. Its official name is'IMT-2020' and it aims to be commercialized globally in 2020.

Layer 2 Relay is being discussed. When the remote UE is connected to the network through Layer 2 Relay (i.e., Layer-2 UE-to-Network Relay), the remote UE transmits NAS messages and RRC messages to the network through the Layer 2 Relay UE, and It is possible to receive a NAS message and an RRC message through the 2 Relay UE. When the remote UE is connected to the network through Layer 2 Relay (ie, Layer-2 UE-to-Network Relay), the network must perform mobility management for the Remote UE.

In EPS, only the RRC_IDLE and RRC_CONNECTED states are defined. However, since the RRC_INACTIVE state is newly defined in 5GS, RRC_INACTIVE needs to be considered.

While the Relay UE is connected to the Remote UE and unicast data is relayed, both the Remote UE and the Relay UE are in RRC_CONNECTED state. Other than that, the RRC states of the relay UE and the remote UE may be independent.

When the remote UE and/or the relay UE are in the RRC_INACTIVE state, there may be a problem in that data on the remote UE is not effectively transmitted to the remote UE.

Accordingly, one disclosure of the present specification aims to provide a solution to the above-described problem.

In order to solve the above-described problem, one disclosure of the present specification provides a method for a base station to perform communication related to a layer 2 relay. The method includes receiving downlink data from a UPF node to a remote UE; Checking whether the remote UE and the relay UEs connected to the remote UE based on the layer 2 relay are all RRC_CONNECTED states; And it may include transmitting a paging message to the relay UE.

In order to solve the above-described problem, one disclosure of the present specification provides a method for a Relay UE to perform a layer 2 relay-related communication. The method includes receiving a paging message from a base station; Transmitting an RRC setup request message or an RRC resumption request message to the base station based on the Relay UE being in the RRC_IDLE state or the RRC_INACTIVE state; And transmitting a paging message to the remote UE based on the paging message related to downlink data to the relay UE and the connected remote UE based on the layer 2 relay.

In order to solve the above-described problem, one disclosure of the present specification provides a base station that performs communication related to a layer 2 relay. The base station includes at least one processor; And at least one memory that stores instructions and is operably electrically connected to the at least one processor, and is executed based on the instruction being executed by the at least one processor. The operation includes: receiving downlink data from the UPF node to the remote UE; Checking whether the remote UE and the relay UEs connected to the remote UE based on the layer 2 relay are all RRC_CONNECTED states; And it may include transmitting a paging message to the relay UE.

In order to solve the above-described problem, one disclosure of the present specification provides a Relay UE that performs communication related to a layer 2 relay. The Relay UE includes at least one processor; And at least one memory that stores instructions and is operably electrically connected to the at least one processor, and is executed based on the instruction being executed by the at least one processor. The operation includes: receiving a paging message from a base station; Transmitting an RRC setup request message or an RRC resumption request message to the base station based on the Relay UE being in the RRC_IDLE state or the RRC_INACTIVE state; And transmitting a paging message to the remote UE based on the paging message related to downlink data to the relay UE and the connected remote UE based on the layer 2 relay.

In order to solve the above-described problem, one disclosure of the present specification provides an apparatus in mobile communication. The device includes at least one processor; And at least one memory that stores instructions and is operably electrically connected to the at least one processor, and is executed based on the instruction being executed by the at least one processor. The operations performed include: identifying a paging message transmitted from a base station; Generating an RRC setup request message or an RRC resumption request message based on the device being in a Radio Resource Control (RRC)_IDLE state or an RRC_INACTIVE state; And generating a paging message to be transmitted to the remote UE based on the paging message related to downlink data to the connected remote UE based on the device and the layer 2 relay.

In order to solve the above-described problem, one disclosure of the present specification provides a non-volatile computer-readable storage medium for recording instructions. The instructions, when executed by one or more processors, cause the one or more processors to: identify a paging message sent from a base station; Generating an RRC setup request message or an RRC resume request message based on the processor being in a Radio Resource Control (RRC)_IDLE state or an RRC_INACTIVE state; And generating a paging message to be transmitted to the remote UE based on the paging message related to downlink data to the connected remote UE based on the processor and the layer 2 relay.

According to the disclosure of the present specification, problems of the prior art can be solved.

The effects that can be obtained through a specific example of the present specification are not limited to the effects listed above. For example, there may be various technical effects that a person having ordinary skill in the related art can understand or derive from the present specification. Accordingly, the specific effects of the present specification are not limited to those explicitly described in the present specification, and may include various effects that can be understood or derived from the technical features of the present specification.

1 is a structural diagram of a next-generation mobile communication network.

2 is an exemplary diagram showing an expected structure of next-generation mobile communication from a node perspective.

3 is an exemplary diagram showing an architecture for supporting simultaneous access to two data networks.

4 is another exemplary diagram showing the structure of a radio interface protocol between a UE and a gNB.

5A and 5B are signal flow diagrams illustrating an exemplary registration procedure.

6A and 6B are signal flow diagrams illustrating an exemplary PDU session establishment procedure.

7A to 7C are signal flow diagrams illustrating an exemplary UE initiated service request procedure.

8 is a signal flow diagram illustrating an exemplary network initiation service request procedure.

9 is a diagram illustrating an example of a procedure for switching from RRC_IDLE triggered by a terminal to RRC_CONNECTED.

10 is a diagram illustrating an example of a procedure for switching from RRC_INACTIVE triggered by a terminal to RRC_CONNECTED.

11 shows an example of the concept of D2D (Device to Device) communication.

12 shows an example of an architecture of a UE-to-Network Relay.

13 shows an example of a protocol stack of a control plane for a UE-to-Network Relay.

14 shows an example of a protocol stack of a user plane for UE-to-Network Relay.

15 shows a signal flow diagram according to a first example of the first example of the disclosure of the present specification.

16 shows a signal flow diagram according to a second example of the first example of the disclosure of the present specification.

17 shows a signal flow diagram according to a second example of the disclosure of the present specification.

18 shows a signal flow diagram according to a third example of the disclosure of the present specification.

19 shows a signal flow diagram according to a fourth example of the disclosure of the present specification.

20 shows a wireless communication system according to an embodiment.

21 illustrates a block diagram of a network node according to an embodiment.

22 is a block diagram showing the configuration of the UE 100 according to an embodiment.

23 is a block diagram showing in detail the transmission/reception unit of the first device shown in FIG. 20 or the transmission/reception unit of the device shown in FIG. 22.

24 illustrates a communication system 1 applied to the disclosure of this specification.

It should be noted that the technical terms used in the present specification are only used to describe specific embodiments and are not intended to limit the content of the present specification. In addition, the technical terms used in the present specification should be interpreted in the meaning generally understood by those of ordinary skill in the technical field to which the disclosure of the present specification belongs, unless otherwise defined in the specification. It should not be construed in a comprehensive or excessively reduced sense. In addition, when a technical term used in the present specification is an incorrect technical term that does not accurately express the contents and spirit of the present specification, a technical term that can be correctly understood by those skilled in the art should be replaced and understood. In addition, general terms used in the present specification should be interpreted as defined in the dictionary or according to the context before and after, and should not be interpreted as an excessively reduced meaning.

In addition, the singular expression used in the present specification includes a plurality of expressions unless the context clearly indicates otherwise. In the present application, terms such as constitute or have should not be construed as necessarily including all of the various components or steps described in the specification, and some components or some steps may not be included, and Or, it should be interpreted that it may further include additional components or steps.

In addition, terms including ordinal numbers such as first and second used herein may be used to describe various elements, but the elements should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the rights, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

When a component is connected to or is said to be connected to another component, it may be directly connected or connected to the other component, but other components may exist in the middle. On the other hand, when a component is directly connected to or directly connected to another component, it should be understood that there is no other component in the middle.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings, but identical or similar elements are denoted by the same reference numerals regardless of reference numerals, and redundant descriptions thereof will be omitted. In addition, in describing the contents of the present specification, when it is determined that a detailed description of related known technologies may obscure the subject matter of the present specification, the detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are for easy understanding of the content and spirit of the present specification, and should not be construed as limiting the content and spirit of the present specification by the accompanying drawings. The content and spirit of this specification should be construed as extending to all changes, equivalents, or substitutes other than the accompanying drawings.

In the present specification, “A or B (A or B)” may mean “only A”, “only B” or “both A and B”. In other words, in the present specification, “A or B (A or B)” may be interpreted as “A and/or B (A and/or B)”. For example, in the present specification, “A, B or C (A, B or C)” refers to “only A”, “only B”, “only C”, or “A, B, and any combination of C ( It can mean any combination of A, B and C)”.

A forward slash (/) or comma used in the present specification may mean "and/or". For example, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B or C”.

In the present specification, “at least one of A and B” may mean “only A”, “only B”, or “both A and B”. In addition, in this specification, the expression “at least one of A or B” or “at least one of A and/or B” means “at least one It can be interpreted the same as "at least one of A and B".

In addition, in the present specification, “at least one of A, B and C” means “only A”, “only B”, “only C”, or “A, B and C Can mean any combination of A, B and C”. In addition, "at least one of A, B or C" or "at least one of A, B and/or C" means It can mean “at least one of A, B and C”.

In addition, parentheses used in the present specification may mean "for example". Specifically, when displayed as “control information (PDCCH)”, “PDCCH” may be proposed as an example of “control information”. In other words, “control information” of the present specification is not limited to “PDCCH”, and “PDDCH” may be suggested as an example of “control information”. In addition, even when indicated as “control information (ie, PDCCH)”, “PDCCH” may be proposed as an example of “control information”.

In the present specification, technical features that are individually described in one drawing may be implemented individually or simultaneously.

In the accompanying drawings, a UE (User Equipment) is illustrated as an example, but the illustrated UE may also be referred to in terms of terminal, mobile equipment (ME), and the like. In addition, the UE may be a portable device such as a notebook computer, a mobile phone, a PDA, a smart phone, or a multimedia device, or may be a non-portable device such as a PC or a vehicle-mounted device.

Hereinafter, the UE is used as an example of a wireless communication device (or wireless device, or wireless device) capable of wireless communication. The operation performed by the UE may be performed by a wireless communication device. The wireless communication device may also be referred to as a wireless device, a wireless device, or the like. Hereinafter, AMF may refer to an AMF node, SMF may refer to an SMF node, and UPF may refer to a UPF node.

A base station, which is a term used below, generally refers to a fixed station that communicates with a wireless device, eNodeB (evolved-NodeB), eNB (evolved-NodeB), BTS (Base Transceiver System), access point ( Access Point), gNB (Next generation NodeB), and other terms.

I. Technologies and procedures applicable to the disclosure of this specification

1 is a diagram of a next-generation mobile communication network It is a structure diagram .

5GC (5G Core) may include various components, and in FIG. 1, AMF (Access and Mobility Management Function) 410 and SMF (session management function: Session Management) corresponding to some of them Function) 420 and PCF (Policy Control Function) 430, UPF (User Plane Function) 440, AF (Application Function) (450), UDM (Integrated Data) Management: Includes Unified Data Management (460) and Non-3GPP Inter Working Function (N3IWF) 490.

The UE 100 is connected to a data network through the UPF 440 through a Next Generation Radio Access Network (NG-RAN) including the gNB 20.

The UE 100 may receive a data service even through untrusted non-3GPP access, for example, a wireless local area network (WLAN). In order to connect the non-3GPP access to the core network, an N3IWF 490 may be deployed.

The illustrated N3IWF 490 performs a function of managing non-3GPP access and interworking between 5G systems. When the UE 100 is connected with non-3GPP access (e.g., WiFi referred to as IEEE 801.11), the UE 100 may be connected with the 5G system through the N3IWF 490. The N3IWF 490 performs control signing with the AMF 410 and is connected to the UPF 440 through an N3 interface for data transmission.

The illustrated AMF 410 may manage access and mobility in a 5G system. The AMF 410 may perform a function of managing non-access stratum (NAS) security. The AMF 410 may perform a function of handling mobility in an idle state.

The illustrated UPF 440 is a type of gateway through which user data is transmitted and received. The UPF node 440 may perform all or part of a user plane function of a serving gateway (S-GW) and a packet data network gateway (P-GW) of 4G mobile communication.

The UPF 440 operates as a boundary point between a next generation RAN (NG-RAN) and a core network, and is an element that maintains a data path between the gNB 20 and the SMF 420. In addition, when the UE 100 moves over an area served by the gNB 20, the UPF 440 serves as a mobility anchor point. The UPF 440 may perform a function of handling a PDU. Packets may be routed in the UPF for mobility within the NG-RAN (Next Generation-Radio Access Network defined after 3GPP Release-15). In addition, UPF 440 is another 3GPP network (RAN defined before 3GPP Release-15, for example, UTRAN, E-UTRAN (Evolved-UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access Network)) or GERAN (GSM ( It may function as an anchor point for mobility with Global System for Mobile Communication)/Enhanced Data rates for Global Evolution (EDGE) Radio Access Network). The UPF 440 may correspond to a termination point of a data interface toward a data network.

The illustrated PCF 430 is a node that controls the operator's policy.

The illustrated AF 450 is a server for providing various services to the UE 100.

The illustrated UDM 460 is a type of server that manages subscriber information, such as a 4G mobile communication HSS (Home Subscriber Server). The UDM 460 stores and manages the subscriber information in a Unified Data Repository (UDR).

The illustrated SMF 420 may perform a function of allocating an Internet Protocol (IP) address of the UE. In addition, the SMF 420 may control a protocol data unit (PDU) session.

For reference, in the following AMF (410), SMF (420), PCF (430), UPF (440), AF (450), UDM (460), N3IWF (490), gNB (20), or UE (100) Reference numerals for may be omitted.

5G mobile communication supports a number of numerology or subcarrier spacing (SCS) to support various 5G services. For example, when the SCS is 15 kHz, it supports a wide area in traditional cellular bands, and when the SCS is 30 kHz/60 kHz, it is dense-urban, lower latency. And a wider carrier bandwidth (wider carrier bandwidth) is supported, and when the SCS is 60 kHz or higher, a bandwidth greater than 24.25 GHz is supported to overcome phase noise.

The NR frequency band may be defined as a frequency range of two types (FR1, FR2). The numerical value of the frequency range may be changed, for example, the frequency range of the two types (FR1, FR2) may be as shown in Table 1 below. For convenience of explanation, among the frequency ranges used in the NR system, FR1 may mean “sub 6GHz range”, and FR2 may mean “above 6GHz range” and may be called millimeter wave (mmWave). .

Frequency Range designation	Corresponding frequency range	Subcarrier Spacing
FR1	450MHz-6000MHz	15, 30, 60 kHz
FR2	24250MHz-52600MHz	60, 120, 240 kHz

As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a band of 410MHz to 7125MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included in FR1 may include an unlicensed band. The unlicensed band can be used for a variety of purposes, and can be used, for example, for communication for vehicles (eg, autonomous driving).

Frequency Range designation	Corresponding frequency range	Subcarrier Spacing
FR1	410MHz-7125MHz	15, 30, 60 kHz
FR2	24250MHz-52600MHz	60, 120, 240 kHz

2 is an exemplary diagram showing an expected structure of next-generation mobile communication from a node perspective. As can be seen with reference to FIG. 2, the UE is connected to a data network (DN) through a next-generation radio access network (RAN).

The illustrated control plane function (CPF) node is all or part of the functions of a mobility management entity (MME) of 4G mobile communication, and a control plane function of a serving gateway (S-GW) and a PDN gateway (P-GW). Do all or part of. The CPF node includes an Access and Mobility Management Function (AMF) and a Session Management Function (SMF).

The illustrated User Plane Function (UPF) node is a type of gateway through which user data is transmitted and received. The UPF node may perform all or part of the user plane functions of S-GW and P-GW of 4G mobile communication.

The illustrated PCF (Policy Control Function) is a node that controls the operator's policy.

The illustrated application function (AF) is a server for providing various services to the UE.

The illustrated Unified Data Management (UDM) is a kind of server that manages subscriber information, such as a 4G mobile communication HSS (Home Subscriber Server). The UDM stores and manages the subscriber information in a Unified Data Repository (UDR).

The illustrated authentication server function (AUSF) authenticates and manages the UE.

The illustrated network slice selection function (NSSF) is a node for network slicing as described below.

The illustrated network exposure function (NEF) is a node for providing a mechanism to securely disclose services and functions of the 5G core. For example, NEF discloses functions and events, securely provides information from external applications to the 3GPP network, translates internal/external information, provides control plane parameters, and provides packet flow description (PFD). ) Can be managed.

In FIG. 3, a UE may simultaneously access two data networks using multiple protocol data unit or packet data unit (PDU) sessions.

3 shows an architecture for supporting simultaneous access to two data networks It is an exemplary diagram .

In FIG. 3, an architecture for a UE to access two data networks simultaneously using one PDU session is shown.

Reference points shown in FIGS. 2 and 3 are as follows.

N1 represents a reference point between the UE and the 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 the reference point between PCF and AF.

N6 represents a reference point between UPF and DN.

N7 represents a reference point between the 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 denotes a reference point between the PCF and the AMF in a non-roaming scenario, and a reference point between the AMF and the 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 represents a reference point between AF and NEF.

For reference, in FIGS. 2 and 3, AF by a third party other than an operator may be connected to 5GC through NEF.

Figure 4 UE and gNB Another showing the structure of the Radio Interface Protocol It is an exemplary diagram .

The air interface protocol is based on the 3GPP radio access network standard. The radio interface protocol is horizontally composed of a physical layer (Physical layer), a data link layer (Data Link layer), and a network layer (Network layer), and vertically, a user plane for data information transmission and control It is divided into a control plane for signal transmission.

The protocol layers are L1 (layer 1), L2 (layer 2), and L3 (layer 3) based on the lower 3 layers of the Open System Interconnection (OSI) reference model widely known in communication systems. ) Can be separated.

In the following, each layer of the radio protocol will be described.

The first layer, the physical layer, provides an information transfer service using a physical channel. The physical layer is connected to an upper medium access control layer through a transport channel, and data between the medium access control layer and the physical layer is transmitted through the transport channel. In addition, data is transmitted between different physical layers, that is, between the physical layers of the transmitting side and the receiving side through a physical channel.

The second layer includes a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, and a Packet Data Convergence Protocol (PDCP) layer.

The third layer includes Radio Resource Control (hereinafter abbreviated as RRC). The RRC layer is defined only in the control plane, and is related to setting (setting), resetting (Re-setting) and release (Release) of radio bearers (Radio Bearer; RB). In charge of control. In this case, RB means a service provided by the second layer for data transmission between the UE and the E-UTRAN.

The NAS (Non-Access Stratum) layer performs functions such as connection management (session management) and mobility management.

The NAS layer is divided into a NAS entity for mobility management (MM) and a NAS entity for session management (SM).

1) NAS entity for MM provides the following functions in general.

NAS procedures related to AMF, including the following.

-Registration management and access management procedures. AMF supports the following functions.

-Secure NAS signal connection between UE and AMF (integrity protection, encryption)

2) The NAS entity for the SM performs session management between the UE and the SMF.

The SM signaling message is processed, that is, generated and processed at the NAS-SM layer of the UE and SMF. The contents of the SM signaling message are not interpreted by the AMF.

-In the case of SM signaling transmission,

-The NAS entity for the MM generates a NAS-MM message that derives how and where to deliver the SM signaling message through the security header representing the NAS transmission of SM signaling, and additional information about the receiving NAS-MM.

-Upon receiving the SM signaling, the NAS entity for the SM performs an integrity check of the NAS-MM message, analyzes the additional information, and derives a method and place to derive the SM signaling message.

Meanwhile, in FIG. 4, an RRC layer, an RLC layer, a MAC layer, and a PHY layer located below the NAS layer are collectively referred to as an Access Stratum (AS).

The network system (ie, 5GC) for next-generation mobile communication (ie, 5G) also supports non-3GPP access. An example of the non-3GPP access is typically WLAN access. The WLAN access may include both a trusted WLAN and an untrusted WLAN.

In a system for 5G, AMF performs registration management (RM: Registration Management) and connection management (CM: Connection Management) for non-3GPP access as well as 3GPP access.

A multi-access (MA) PDU session using both 3GPP access and non-3GPP access may be used.

The MA PDU session is a PDU session capable of simultaneously serving 3GPP access and non-3GPP access using one PDU session.

5A and 5B are signal flow diagrams illustrating an exemplary registration procedure.

1) The UE can transmit an AN message to the RAN. The AN message may include an AN parameter and a registration request message. The registration request message may include information such as registration type, subscriber permanent ID or temporary user ID, security parameters, Network Slice Selection Assistance Information (NSSAI), 5G capability of the UE, and protocol data unit (PDU) session state.

In the case of a 5G RAN, the AN parameter may include a SUPI (Subscription Permanent Identifier) or a temporary user ID, a selected network, and NSSAI.

The registration type is "initial registration" (ie, the UE is in a non-registered state), "mobility registration update" (ie, the UE is in a registered state and starts the registration process due to mobility) or "regular registration update" ( That is, it may indicate whether the UE is in a registered state and starts a registration procedure due to periodic update timer expiration). When the temporary user ID is included, the temporary user ID indicates the last serving AMF. If the UE has already been registered through non-3GPP access in a PLMN different from the PLMN of 3GPP access, the UE may not provide the temporary ID of the UE allocated by the AMF during the registration procedure through the non-3GPP access.

Security parameters can be used for authentication and integrity protection.

The PDU session state may indicate a (previously established) PDU session available in the UE.

2) If SUPI is included or the temporary user ID does not indicate a valid AMF, the RAN may select AMF based on (R)AT and NSSAI.

If the (R)AN cannot select an appropriate AMF, it selects a random AMF according to local policy, and transmits a registration request to the selected AMF. If the selected AMF cannot serve the UE, the selected AMF selects another AMF more appropriate for the UE.

3) The RAN transmits an N2 message to a new AMF. The N2 message includes an N2 parameter and a registration request. The registration request may include a registration type, a subscriber permanent identifier or a temporary user ID, a security parameter, and a default setting of NSSAI and MICO modes.

When 5G-RAN is used, the N2 parameter includes location information related to a cell in which the UE is camping, a cell identifier and a RAT type.

If the registration type indicated by the UE is a periodic registration update, steps 4 to 17 described below may not be performed.

4) The newly selected AMF may transmit an information request message to the previous AMF.

If the temporary user ID of the UE is included in the registration request message and the serving AMF has changed since the last registration, the new AMF can send an information request message containing complete registration request information to the previous AMF to request the SUPI and MM context of the UE. have.

5) The previous AMF transmits an information response message to the newly selected AMF. The information response message may include SUPI, MM context, and SMF information.

Specifically, the previous AMF transmits an information response message including the SUPI and MM context of the UE.

-When there is information on an active PDU session in the previous AMF, SMF information including the ID of the SMF and the PDU session ID may be included in the information response message in the previous AMF.

6) The new AMF transmits an Identity Request message to the UE if SUPI is not provided by the UE or is not retrieved from the previous AMF.

7) The UE transmits an Identity Response message including the SUPI to the new AMF.

8) AMF may decide to trigger AUSF. In this case, AMF may select AUSF based on SUPI.

9) AUSF can initiate authentication of UE and NAS security functions.

10) The new AMF may transmit an information response message to the previous AMF.

If the AMF is changed, the new AMF may transmit the information response message to confirm delivery of the UE MM context.

-If the authentication/security procedure fails, registration is rejected and the new AMF can send a rejection message to the previous AMF.

11) The new AMF may transmit an Identity Request message to the UE.

If the PEI has not been provided by the UE or has not been retrieved from the previous AMF, an Identity Request message may be sent for the AMF to retrieve the PEI.

12) The new AMF checks the ME identifier.

13) If step 14 described later is performed, the new AMF selects UDM based on SUPI.

14) After the final registration, if the AMF is changed, there is no valid subscription context for the UE in the AMF, or the UE provides a SUPI that does not refer to a valid context in the AMF, the new AMF starts the update location procedure. . Alternatively, it may be initiated even when the UDM initiates a cancel location for the previous AMF. The old AMF discards the MM context and notifies all possible SMF(s), and the new AMF creates an MM context for the UE after obtaining the AMF-related subscription data from the UDM.

When network slicing is used, AMF acquires the NSSAI allowed based on the requested NSSAI, UE subscription and local policy. If AMF is not suitable to support the allowed NSSAI, it will reroute the registration request.

15) The new AMF can select a PCF based on SUPI.

16) The new AMF transmits a UE Context Establishment Request message to the PCF. The AMF may request an operator policy for the UE from the PCF.

17) The PCF transmits a UE Context Establishment Acknowledged message to the new AMF.

18) The new AMF transmits an N11 request message to the SMF.

Specifically, when the AMF is changed, the new AMF notifies each SMF of the new AMF serving the UE. The AMF verifies the PDU session state from the UE with available SMF information. When the AMF is changed, usable SMF information may be received from the previous AMF. The new AMF may request the SMF to release network resources related to a PDU session that is not active in the UE.

19) The new AMF transmits an N11 response message to the SMF.

20) The previous AMF transmits a UE Context Termination Request message to the PCF.

If the previous AMF has previously requested that the UE context be set in the PCF, the previous AMF may delete the UE context in the PCF.

21) The PCF may transmit a UE Context Termination Request message to the previous AMF.

22) The new AMF transmits a registration acceptance message to the UE. The registration acceptance message may include a temporary user ID, a registration area, mobility restriction, PDU session state, NSSAI, a regular registration update timer, and an allowed MICO mode.

The registration acceptance message may include the allowed NSSAI and information of the mapped NSSAI. The allowed NSSAI information on the access type of the UE may be included in an N2 message including a registration acceptance message. The mapped NSSAI information maps each S-NSSAI (Session Network Slice Selection Assistance Information) of the allowed Network Slice Selection Assistance Information (NSSAI) to the S-NASSI of the NSSAI configured for Home Public Land Mobile Network (HPLMN). It is one information.

When the AMF allocates a new temporary user ID, a temporary user ID may be further included in the registration acceptance message. When mobility limitation is applied to the UE, information indicating mobility limitation may be additionally included in the registration acceptance message. The AMF may include information indicating the PDU session state for the UE in the registration acceptance message. The UE may remove any internal resources related to a PDU session that is not marked as active in the received PDU session state. If the PDU session state information is in the Registration Request, the AMF may include information indicating the PDU session state to the UE in the registration acceptance message.

23) The UE transmits a registration completion message to the new AMF.

< PDU Session establishment procedure>

As for the protocol data unit (PDU) session establishment procedure, there may be two types of PDU session establishment procedures as follows.

-PDU session establishment procedure initiated by the UE

-PDU session establishment procedure initiated by the network. To this end, the network may transmit a device trigger message to the application(s) of the UE.

6A and 6B are exemplary PDU This is a signal flow diagram showing a procedure for establishing a session.

The procedures shown in FIGS. 6A and 6B assume that the UE has already registered on the AMF according to the registration procedure shown in FIGS. 5A and 5B. Therefore, it is assumed that the AMF has already obtained user subscription data from UDM.

1) The UE transmits a NAS message to AMF. The message may include Session Network Slice Selection Assistance Information (S-NSSAI), DNN, PDU session ID, request type, N1 SM information, and the like.

Specifically, the UE includes the S-NSSAI from the allowed NSSAI of the current access type. If information on the mapped NSSAI is provided to the UE, the UE may provide both the S-NSSAI based on the allowed NSSAI and the corresponding S-NSSAI based on the information of the mapped NSSAI. Here, the mapped NSSAI information is information obtained by mapping each S-NSSAI of the allowed NSSAI to the S-NASSI of the NSSAI set for HPLMN.

More specifically, the UE extracts and stores information of the allowed S-NSSAI and the mapped S-NSSAI included in the registration acceptance message received from the network (ie, AMF) in the registration procedure of FIGS. 7A and 7B Can be doing. Accordingly, the UE may include and transmit both the S-NSSAI based on the allowed NSSAI and the corresponding S-NSSAI based on information of the mapped NSSAI in the PDU session establishment request message.

To establish a new PDU session, the UE may generate a new PDU session ID.

The UE may initiate a PDU session establishment procedure initiated by the UE by transmitting a NAS message including a PDU session establishment request message in N1 SM information. The PDU session establishment request message may include a request type, an SSC mode, and a protocol configuration option.

When the PDU session establishment is to establish a new PDU session, the request type indicates "initial request". However, when there is an existing PDU session between 3GPP access and non-3GPP access, the request type may indicate "existing PDU session".

The NAS message transmitted by the UE is encapsulated in the N2 message by the AN. The N2 message is transmitted through AMF, and may include user location information and access technology type information.

-The N1 SM information may include an SM PDU DN request container that includes information on PDU session authentication by an external DN.

2) The AMF may determine that the message corresponds to a request for a new PDU session when the request type indicates "initial request" and when the PDU session ID is not used for the existing PDU session of the UE.

If the NAS message does not include the S-NSSAI, the AMF may determine the default S-NSSAI for the requested PDU session according to the UE subscription. The AMF may store the PDU session ID and the SMF ID in association with each other.

3) AMF transmits an SM request message to the SMF. The SM request message may include a subscriber permanent ID, DNN, S-NSSAI, PDU session ID, AMF ID, N1 SM information, user location information, and access technology type. The N1 SM information may include a PDU session ID and a PDU session establishment request message.

The AMF ID is used to identify the AMF serving the UE. The N1 SM information may include a PDU session establishment request message received from the UE.

4a) SMF transmits a subscriber data request message to UDM. The subscriber data request message may include a subscriber permanent ID and DNN.

In step 3 above, if the request type indicates "existing PDU session", the SMF determines that the request is due to handover between 3GPP access and non-3GPP access. The SMF can identify an existing PDU session based on the PDU session ID.

If the SMF has not yet retrieved the SM-related subscription data for the DNN-related UE, the SMF may request subscription data.

4b) UDM may transmit a subscription data response message to the SMF.

The subscription data may include information on an authenticated request type, an authenticated SSC mode, and a basic QoS profile.

The SMF can check whether the UE request complies with the user subscription and local policy. Alternatively, the SMF rejects the UE request through NAS SM signaling (including the related SM rejection cause) delivered by the AMF, and the SMF informs the AMF that the PDU session ID should be considered released.

5) SMF sends a message to DN through UPF.

Specifically, when the SMF needs to approve/authenticate PDU session establishment, SMF selects UPF and triggers PDU.

If PDU session establishment authentication/authorization fails, the SMF terminates the PDU session establishment procedure and notifies the UE of rejection.

6a) When dynamic PCC (Policy and Charging Control) is deployed, SMF selects PCF.

6b) The SMF may initiate PDU-CAN session establishment towards the PCF to obtain basic PCC rules for the PDU session. If the request type in step 3 indicates "existing PDU session", the PCF may start modifying the PDU-CAN session instead.

7) If the request type of step 3 indicates "initial request", the SMF selects the SSC mode for the PDU session. If step 5 is not performed, the SMF may also select UPF. In case of request type IPv4 or IPv6, SMF may allocate an IP address/prefix for a PDU session.

8) If a dynamic PCC is deployed and PDU-CAN session establishment has not yet been completed, the SMF can start the PDU-CAN session.

9) If the request type indicates "initial request" and step 5 is not performed, the SMF starts the N4 session establishment procedure using the selected UPF, otherwise the N4 session modification procedure can start using the selected UPF.

9a) SMF transmits an N4 session establishment/modification request message to the UPF. In addition, the SMF may provide a packet detection, enforcement and reporting rule to be installed in the UPF for the PDU session. When the SMF is allocated CN tunnel information, CN tunnel information may be provided to the UPF.

9b) UPF can respond by transmitting an N4 session establishment/modification response message. When CN tunnel information is allocated by UPF, CN tunnel information may be provided to the SMF.

10) The SMF transmits an SM response message to the AMF. The message may include cause, N2 SM information, and N1 SM information. The N2 SM information may include PDU session ID, QoS profile, and CN tunnel information. The N1 SM information may include a PDU session establishment acceptance message. The PDU session establishment acceptance message may include a permitted QoS rule, SSC mode, S-NSSAI, and an assigned IPv4 address.

The N2 SM information is information that the AMF must deliver to the RAN and may include the following.

-CN tunnel information: This corresponds to the core network address of the N3 tunnel corresponding to the PDU session.

-QoS Profile: This is used to provide a mapping between QoS parameters and QoS flow identifiers to the RAN.

-PDU Session ID: This may be used to indicate to the UE the association between the PDU session and AN resources for the UE by AN signaling for the UE.

Meanwhile, the N1 SM information includes a PDU session acceptance message that the AMF must provide to the UE.

Multiple QoS rules may be included in the N1 SM information and the N2 SM information in the PDU session establishment acceptance message.

-The SM response message also contains information that allows the PDU session ID and AMF to determine which target UE as well as which access should be used for the UE.

11) AMF transmits an N2 PDU session request message to the RAN. The message may include N2 SM information and NAS message. The NAS message may include a PDU session ID and a PDU session establishment acceptance message.

The AMF may transmit a NAS message including a PDU session ID and a PDU session establishment acceptance message. Also, the AMF includes received N2 SM information from the SMF in the N2 PDU session request message and transmits it to the RAN.

12) The RAN may exchange specific signaling with the UE related to information received from the SMF.

The RAN also allocates RAN N3 tunnel information for the PDU session.

The RAN delivers the NAS message provided in step 10 to the UE. The NAS message may include PDU session ID and N1 SM information. The N1 SM information may include a PDU session establishment acceptance message.

The RAN transmits a NAS message to the UE only when necessary RAN resources are set and allocation of RAN tunnel information is successful.

13) The RAN transmits an N2 PDU session response message to the AMF. The message may include PDU session ID, cause, and N2 SM information. The N2 SM information may include a PDU session ID, (AN) tunnel information, and a list of allowed/rejected QoS profiles.

-RAN tunnel information may correspond to the access network address of the N3 tunnel corresponding to the PDU session.

14) The AMF may transmit an SM request message to the SMF. The SM request message may include N2 SM information. Here, the AMF may be to transmit the N2 SM information received from the RAN to the SMF.

15a) If the N4 session for the PDU session has not already been established, the SMF may start the N4 session establishment procedure together with the UPF. Otherwise, the SMF can start the N4 session modification procedure using UPF. SMF may provide AN tunnel information and CN tunnel information. CN tunnel information may be provided only when the SMF selects CN tunnel information in step 8.

15b) The UPF may transmit an N4 session establishment/modification response message to the SMF.

16) The SMF may transmit an SM response message to the AMF. When this process is over, the AMF can deliver the related event to the SMF. Occurs at handover when RAN tunnel information is changed or AMF is relocated.

17) SMF transmits information to the UE through UPF. Specifically, in the case of PDU Type IPv6, the SMF may generate an IPv6 Router Advertisement and transmit it to the UE through N4 and UPF.

18) When the PDU session establishment request is due to a handover between 3GPP access and non-3GPP access, that is, when the request type is set to “existing PDU session”, the SMF is Release the plane.

19) If the ID of the SMF is not included in process 4b by the UDM of the DNN subscription context, the SMF may call "UDM_Register UE serving NF service" including the SMF address and DNN. UDM can store SMF's ID, address, and related DNN.

During the procedure, if the PDU session establishment is not successful, the SMF notifies the AMF.

<Service Request procedures>

The service request procedure is used to request establishment of a secure connection to the AMF by the UE or 5GC (5G Core network). The service request procedure is used to activate the user plane connection of the established PDU session even when the UE is in the CM-IDLE state and the CM-CONNECTED state. For reference, in order to reflect the NAS signaling connection between the AMF and the UE, two CM states of a CM-IDLE state and a CM-CONNECTED state are used.

The UE does not initiate a service request procedure if there is an ongoing service request procedure.

The service request procedure includes a service request procedure initiated by the UE (i.e., a UE-initiated service request (UE Triggered Service Request)) and a service request procedure initiated by the network (i.e., a network triggered service request). .

Hereinafter, an example of a UE initiation service request procedure will be described with reference to FIGS. 7A to 7C, and an example of a network initiation service request procedure will be described with reference to FIG. 9. The service request procedure described in FIGS. 7A to 7C and 9 is only an example, and the service request procedure in the disclosure of this specification includes all the service request procedures initiated by the UE and all the service request procedures initiated by the network. It may include.

Fig. 7a To 7c is exemplary UE This is a signal flow diagram showing a procedure for requesting an initiation service.

The UE in the CM-ILDE state initiates a service request procedure to transmit a response to an uplink signaling message, user data or network paging request. After receiving the service request message, the AMF may perform authentication. After establishing the signaling connection for the AMF, the UE or the network may transmit a signaling message (eg, establishment of a PDU session from the UE to the SMF through the AMF).

The service request procedure may be used by the UE in the CM-CONNECTED state to request activation of the user plane connection for the PDU session and to respond to the NAS notification message received from the AMF.

For any service request procedure, the AMF may include state information of the PDU session in a service accept message to synchronize the PDU session state between the UE and the network, if necessary.

If the service request is not accepted by the network, the AMF responds to the UE with a Service Reject message. The service rejection message may include an indication or a cause code for requesting that the UE perform a registration update procedure.

In the UE initiated service request procedure, both SMF and UPF belong to the PLMN serving the UE. For example, in the home routed roaming case, the SMF and UPF of the HPLMN are not affected by the service request procedure (that is, the SMF and UPF of the HPLMN are not involved in the service request procedure).

For a service request according to user data, the network can take further action if the user plane connection activation is not successful.

The UE initiated service request procedure can be applied to scenarios with or without intermediate UPF and scenarios with or without intermediate UPF reselection.

1) Signaling from UE to (R)AN: The UE sends an AN (Access Network) message (AN parameter, service request (List Of PDU Sessions To Be Activated), list of allowed PDU sessions ( List Of Allowed PDU Sessions), security parameters (including security parameters and PDU session status)) can be transmitted to the (R)AN.

The list of PDU sessions to be activated is provided by the UE when the UE attempts to re-activate the PDU session. The list of allowed PDU sessions is provided by the UE when the service request is a response to a NAS notification or paging of a PDU session related to non-3GPP access. And, the list of allowed PDU sessions identifies PDU sessions that can be moved to 3GPP access.

For NG-RAN:

-The AN parameter includes the selected PLMN ID and establishment cause. The establishment cause provides a reason for requesting establishment of an RRC connection.

-The UE transmits a service request message (message to AMF) encapsulated in the RRC message to the NG-RAN. The RRC message may be used to carry 5G-S-TMSI (5G S (SAE: System Architecture Evolution)-Temporary Mobile Subscriber Identity).

When a service request is triggered for user data, the UE notifies a PDU session in which UP (User Plane) connection is to be activated in a service request message using a list of PDU sessions to be activated (List Of PDU Sessions To Be Activated).

When the service request is triggered only for signaling, the UE does not include a list of PDU sessions to be activated (List Of PDU Sessions To Be Activated).

When the service request procedure is triggered for a paging response and the UE has user data to be transmitted at the same time, the UE uses the list of PDU sessions to be activated (List Of PDU Sessions To Be Activated) to be activated in the service request message. PDU sessions having a can be announced. Otherwise, the UE does not announce any PDU session in the service request for paging response.

In a specific case, even when there is no pending uplink data of PDU sessions, when a service request is triggered only for signaling, or when a service request is triggered for a paging response, the UE lists the PDU sessions to be activated (List Of PDU Sessions To Be Activated) can include a PDU session.

When a service request through 3GPP access is triggered in response to a NAS notification indicating paging or non-3GPP access, a non-3GPP PDU session that can be re-activated through 3GPP is included in the allowed PDU session list and transmitted. . (See the example to be described in step 6 of FIG. 9).

The PDU session state represents a PDU session available in the UE.

If the UE is located outside the available area of the LADN, the UE does not trigger a service request procedure for a PDU session corresponding to the LADN. And when the service request is triggered for other reasons, the UE does not include such a PDU session in the list of PDU sessions to be activated (List Of PDU Sessions To Be Activated).

When the UE is in the CM-CONNETED state, only a list of PDU sessions to be activated (List Of PDU Sessions To Be Activated) and a list of allowed PDU sessions may be included in the service request.

2) Signaling from (R)AN to AMF: (R)AN can transmit an N2 message to AMF. The N2 message may include N2 parameters, a service request, and a UE context request.

If the AMF is unable to handle the service request, the AMF will reject the service request.

When the NG-RAN is used, the N2 parameter may include 5G-S-TMSI, a selected PLMN ID, location information, and establishment cause.

When the UE is in the CM-IDLE state, the NG-RAN may acquire 5G-S-TMSI in the RRC procedure. The NG-RAN may select AMF based on 5G-S-TMSI. The location information is related to a cell in which the UE camps.

Based on the PDU session state, the AMF may perform a PDU session release procedure for PDU sessions indicated by the UE that the PDU session ID is not available in the network.

3a) Signaling from AMF to (R)AN: AMF may transmit an N2 request to (R)AN. Here, the N2 request is a security context, a handover restriction list, and a list of recommended cells/TAs/NG-RAN node identifiers (list of recommended cells / TAs / NG-RAN node identifiers). It may include.

When the 5G-AN requests for the UE context or the AMF needs to provide the UE context (e.g., when the AMF needs to initiate a fallback procedure for emergency service), the AMF is NGAP (NG Application Protocol) procedure can be initiated. For a UE in CM-IDLE state, 5G-AN stores the security context in the UE AN context. The handover restriction list is related to mobility restrictions.

5G-AN uses the security context to protect messages exchanged with the UE.

If the NG-RAN node provided a list of recommended cells/TAs/NG-RAN node identifiers during the AN release procedure, the AMF will include a list of recommended cells/TAs/NG-RAN node identifiers in the N2 request. I can. When the RAN decides to enable the RRC Inactive state for the UE, the RAN may use this information to allocate the RAN Notification Area.

3) If the service request is not transmitted with integrity protected or integrity protection verification failed, AMF may initiate a NAS authentication/security procedure.

When the UE in the CM-IDLE state initiates a service request only for signaling connection, the UE and the network can exchange NAS signaling after successful establishment of the signaling connection, and steps 4 to 11 and steps of FIGS. 7A to 7C 15 to 22 may be omitted.

4) [conditional operation] Signaling from AMF to SMF: The AMF may transmit an Nsmf_PDUSession_UpdateSMContext Request to the SMF. Here, the Nsmf_PDUSession_UpdateSMContext Request is a PDU session ID, operation type, UE location information, access type, RAT type, and UE presence in LADN service area. Can include.

Nsmf_PDUSession_UpdateSMContext Request is called in the following cases:

-When the UE includes a list of PDU sessions to be activated in the service request message (List Of PDU Sessions To Be Activated);

-If this procedure is triggered by the SMF, but the PDU session identified by the UE is correlated with the PDU session ID that triggers this procedure and a different PDU session ID;

-Although this procedure is triggered by the SMF, there is a case where the current UE location is outside the "Area of validity for the N2 SM information" provided by the SMF (see step 3a in FIG. 9). . In this case, the AMF does not transmit the N2 information provided by the SMF (see step 3a of FIG. 9). If the current UE location is outside the "available area of N2 SM information", steps 4 to 11 are omitted.

If the DNN corresponds to the LADN, "the presence of the UE in the LADN service area" indicates whether the UE is inside (IN) or outside the LADN service area (OUT). If the AMF does not provide the "UE presence in the LADN service area" indication and the SMF determines that the DNN corresponds to the LADN, the SMF considers the UE to be outside the LADN service area.

The AMF determines whether the PDU session(s) will be activated. In addition, the AMF transmits an Nsmf_PDUSession_UpdateSMContext Request related to the PDU session to the SMF together with an operation type set to "UP active" to indicate establishment of a user plane resource for a PDU session. The AMF determines the access type and the RAT type based on the global RAN node ID related to the N2 interface.

If this procedure is triggered in response to a paging or NAS notification indicating non-3GPP access, and the UE is not in the list of allowed PDU sessions (provided from the UE), the PDU session being paged or notified, the AMF sends the PDU to the SMF. It can be notified that the user plane for the session cannot be reactivated. The service request procedure can be terminated without reactivation of the user plane for other PDU sessions in the list of allowed PDU sessions.

While the previous NAS signaling connection through the NG-RAN is maintained, the AMF may receive a service request through the NG-RAN to establish another NAS signaling connection. In this case, in order to release the previous NAS signaling connection, AMF may trigger an AN release procedure for the previous NG-RAN (old NG-RAN) according to the following logic:

-For a PDU session indicated in "List Of PDU Sessions To Be Activated", AMF may request the SMF to immediately activate the PDU session by performing this step 4.

-Included in the "List of PDU Session ID(s) with active N3 user plane", but in the "List Of PDU Sessions To Be Activated" For a PDU session that is not included, the AMF may request the SMF to deactivate the PDU session.

5) If the PDU session ID corresponds to the LADN and the SMF determines that the UE is located outside the LADN availability area based on "the presence of the UE in the LADN service area" provided from the AMF, the SMF (based on the local policy) You may decide to perform the following actions:

-SMF can maintain the PDU session. However, the SMF may reject the activation of the user plane connection of the PDU session and notify the AMF. When the service request procedure is triggered by the network initiation service request of FIG. 9, the SMF is used to discard the downlink data for the PDU session and/or not to provide an additional data notification message. You may notify this to; or

-The SMF can release the PDU session: The SMF can release the PDU session and notify the AMF that the PDU session has been released.

-In the above two cases, the SMF responds to the AMF with an appropriate reject cause, and user plane activation of the PDU session may be stopped.

When the SMF determines that the UE is located in the LADN available area, based on the location information received from the AMF, the SMF may determine the UPF selection criteria and decide to perform one of the following operations:

-SMF accepts the activation of the UP connection and can continue to use the current UPF;

-When the UE moves outside the service area of the UPF (UPF that was previously connected to the AN), the SMF maintains the UPF acting as a PDU Session Anchor, while the SMF accepts the activation of the UP connection and You can select an intermediate UPF (or add/remove intermediate UPFs (I-UPF)). The steps to perform the addition/change/removal of the I-UPF are described through conditional steps below.

NOTE 1: For connectivity to local access to data networks, existing (old) and/or new (new) I-UPFs implement UL Uplink Classifier (CL) or Branching Point (BP) functions and PDU session anchors. In this case, the signaling described in this drawing is intended as signaling for adding, removing, or changing a PDU session anchor, and signaling for adding, releasing, or changing UL CL or BP, respectively, must be completed by a different procedure. .

-The SMF may refuse to activate the UP connection of the PDU session in Session and Service Continuity (SSC) mode 2. And, after the service request procedure, the SMF may trigger re-establishment of a PDU session in order to allocate a new UPF (UPF acting as a PDU session anchor). (This operation may be performed, for example, when the UE is moved outside the service area of the anchor UPF connected to the NG-RAN)

6a) [Conditional operation] Signaling from SMF to new UPF (or new I-UPF): The SMF may transmit an N4 Session Establishment Request to the UPF.

When the SMF selects a new UPF acting as an I-UPF for a PDU session, or when the SMF chooses to insert an I-UPF for a PDU session (which did not have an I-UPF), the SMF requests to establish an N4 session. Can be transmitted to UPF. Here, the N4 establishment request provides packet detection, data forwarding, enforcement, and reporting rules to be installed in the I-UPF. PDU session anchor addressing information for a PDU session (PDU session anchor addressing information at an N9 reference point (a reference point between two UPFs)) is also provided to the I-UPF.

When a service request is triggered by the network and the SMF selects a new UPF to replace the existing UPF (or existing I-UPF), the SMF includes a data forwarding indication in the N4 session establishment request. I can make it. The data delivery indication may be provided from the previous I-UPF to indicate to the UPF that the second tunnel endpoint needs to be reserved for buffered DL data.

6b) Signaling from the new UPF (or I-UPF) to the SMF: The new UPF (or I-UPF) may transmit an N2 Session Establishment Response to the SMF.

The new I-UPF may transmit an N4 session establishment response to the SMF. When the UPF allocates CN tunnel information, the new I-UPF may transmit DL Core Network (CN) tunnel information for the UPF acting as a PDU session anchor and UL tunnel information of the new I-UPF to the SMF. When a data transfer indication is received, a new UPF (or I-UPF) operating as an N3 terminating point is a DL tunnel of a new I-UPF for data transfer from the existing UPF (or I-UPF) to the SMF. Information can be transmitted to the SMF. If the previous I-UPF resource exists, in order to release the corresponding resource, the SMF may drive a timer to be used in step 22a.

7a) [Conditional operation] Signaling from SMF to UPF (PSA: PDU Session Anchor): The SMF may transmit an N4 session modification request to the UPF.

When the SMF selects a new UPF to operate as an I-UPF for a PDU session, the SMF may transmit an N4 session modification request message to the PDU session anchor UPF to provide DL tunnel information received from the new I-UPF. When a new I-UPF is added for a PDU session, the UPF (PSA) may provide DL data to the new I-UPF as indicated in the DL tunnel information.

If the service request is triggered by the network, the SMF removes the existing I-UPF and does not replace the existing I-UPF with a new I-UPF, the SMF will include the data delivery indication in the N4 session modification request. I can. The data delivery indication may indicate to the UPF (PSA) that the second tunnel endpoint needs to be reserved for the buffered DL data received from the existing I-UPF. In this case, the UPF (PSA) may start buffering DL data that can be simultaneously received from the N6 interface.

7b) UPF (PSA) may transmit an N4 Session Modification Response message to the SMF.

When the UPF (PSA) receives the data delivery indication, the UPF (PSA) becomes an N3 endpoint, and the UPF (PSA) may transmit CN DL tunnel information for the previous UPF (or I-UPF) to the SMF. . SMF can drive a timer. If the previous I-UPF resource exists, in order to release the corresponding resource, the SMF may drive a timer to be used in step 22a.

The UPF connected to the RAN is UPF (PAS), and the SMF receives the Nsmf_PDUSession_UpdateSMContext Request in step 4 (including an operation type set to "UP activate" to instruct establishment of user plane resources for the PDU session) When the SMF knows that the PDU session has been activated, the SMF may initiate an N4 session modification procedure to remove the AN tunnel information and remove the AN tunnel information from the UPF.

8a) [Conditional operation] Signaling from the SMF to the existing UPF (or I-UPF): SMF sends an N4 session modification request (including a new UPF address and a new UPF DL tunnel ID) to the existing UPF (or I-UPF). Can be transmitted.

When a service request is triggered by the network and the SMF removes the existing UPF (or I-UPF), the SMF sends an N4 session modification request message to the existing UPF (or I-UPF) to DL tunnel information can be provided. When the SMF allocates a new I-UPF, the DL tunnel information is received from a new UPF (or I-UPF) operating as an N3 endpoint. If the SMF does not allocate a new I-UPF, the DL tunnel information is transmitted from the UPF (PSA) operating as an N3 endpoint. The SMF may drive a timer for monitoring a forwarding tunnel as in step 6b or 7b.

When the SMF receives the Nsmf_PDUSession_UpdateSMContext Request in step 4 (including an operation type set to "UP activate" to instruct the establishment of user plane resources for the PDU session), the SMF indicates that the PDU session has been activated. If known, the SMF may remove the AN tunnel information and initiate the N4 session modification procedure in order to remove the tunnel information of the AN from the UPF.

8b) Signaling from the existing UPF (or I-UPF) to the SMF: The existing UPF (or I-UPF) may transmit an N4 session modification response message to the SMF.

9) [Conditional operation] Signaling from an existing UPF (or I-UPF) to a new UPF (or I-UPF): The existing UPF (or I-UPF) is a downlink buffered with a new UPF (or I-UPF) Can pass data.

When the I-UPF is changed and a forwarding tunnel is established for a new I-UPF, the existing UPF (or I-UPF) transfers the data buffered in the existing UPF (or I-UPF) to the N3 endpoint. It passes to a new UPF (or I-UPF) that is running.

10) [Conditional operation] Signaling from the existing UPF (or I-UPF) to the UPF (PSA): The existing UPF (or I-UPF) can transfer downlink data buffered by the UPF (PSA).

When the existing I-UPF is removed, a new I-UPF is not allocated for the PDU session, and a forwarding tunnel is established for UPF (PSA), the existing UPF (or I-UPF) is -UPF) buffered data can be transferred to a new UPF (PSA) acting as an N3 endpoint.

11) [Conditional operation] Signaling from SMF to AMF: SMF may transmit Nsmf_PDUSession_UpdateSMContext Response to AMF. Nsmf_PDUSession_UpdateSMContext Response is N2 SM information (PDU session ID, QFI(s) (QoS Flow ID), QoS (Quality of Service) profile, CN N3 tunnel information, S-NSSAI, User Plane Security Enforcement), UE It may include an integrity protection maximum data rate (UE Integrity Protection Maximum Data Rate) and a cause. When the UPF connected to the RAN is UPF (PSA), the CN N3 tunnel information is UL tunnel information of UPF (PSA). When the UPF connected to the RAN is a new I-UPF, the CN N3 tunnel information is UL tunnel information of the I-UPF.

For the PDU session in which the SMF decides to accept the activation of the UP connection in step 5, the SMF may generate only N2 SM information and transmit an Nsmf_PDUSession_UpdateSMContext Response to the AMF to establish a user plane. The N2 SM information may include information to be provided by AMF to the NG-RAN. When the SMF decides to change the PSA UPF for the SSC mode 3 PDU session, the SMF may trigger the change of the SSC mode 3 PDU session anchor as an independent procedure after accepting UP activation of the PDU session.

The SMF may reject the activation of the UP of the PDU session by including the cause in the Nsmf_PDUSession_UpdateSMContext Response. The SMF may reject activation of the UP of the PDU session in the following cases, for example:

-If the PDU session corresponds to the LADN as in step 5, and the UE is located outside the available area of the LADN;

When the AMF informs the SMF that the UE is reachable only for a regulatory prioritized service, and the PDU session to be activated is not for a regulatory priority service; or

-As in step 5, when the SMF decides to change the PSA UPF for the requested PDU session. In this case, after the SMF transmits the Nsmf_PDUSession_UpdateSMContext Response, the SMF may perform another procedure to instruct the UE to re-establish the PDU session for SSC mode 2.

-SMF receives negative response in step 6b due to UPF resource unavailability.

When the EPS bearer ID is assigned to the PDU session, the SMF maps the EPS bearer ID and QFI to N2 SM information and transmits it to the NG-RAN.

User Plane Security Enforcement information is determined by the SMF during the PDU session establishment procedure. User plane security enforcement information, if the integrity protection (Integrity Protection) indicates "preffered" or "required", SMF may also include the UE integrity protection maximum data rate (UE Integrity Protection Maximum Data Rate). have.

12) Signaling from AMF to (R)AN: AMF may transmit an N2 request to (R)AN. N2 request is N2 SM information received from SMF, security context (security context), handover restriction list (Handover Restriction List), subscribed UE-AMBR (Subscribed UE-AMBR (Aggregate Maximum Bit Rate)), MM NAS service acceptance (MM NAS Service Accept may include a list of recommended cells/TAs/NG-RAN node identifiers, and UE Radio Capability. Allowed NSSAI for the access type of the UE may be included in the N2 message. have.

When the UE triggers a service request while the UE is in the CM-CONNECTED state, only the N2 SM information received from the SMF and the MM NAS service acceptance may be included in the N2 request in the N2 request.

While the UE is in the CM-CONNECTED state, when a service request procedure is triggered by the network, only N2 SM information received from the SMF may be included in the N2 request.

For the UE that was in the CM-IDLE state when the service request procedure was triggered, the NG-RAN may store the security context and NAS signaling connection Id. When the service request is not triggered by the UE only for the signaling connection, the RAN may store QoS information for the QoS flow of the activated PDU session, the N3 tunnel ID of the UE RAN context, and the handover restriction list.

Acceptance of MM NAS service may include AMF's PDU session state. During the session request procedure, any local PDU session release may be notified to the UE through the PDU session state. The service acceptance message includes the result of PDU session reactivation. The PDU session reactivation result provides the PDU session in the list of PDU sessions to be activated (List Of PDU Sessions To Be Activated) and the PDU session in the list of allowed PDU sessions that caused paging or NAS notification. When the PDU session reactivation result of the PDU session is failure, the cause of the failure may also be provided.

When there are a plurality of PDU sessions related to a plurality of SMFs, the AMF need not wait for responses from all SMFs in step 11. However, the AMF must wait for all responses from the plurality of SMFs before transmitting the MM NAS service acceptance message to the UE.

When step 12 is triggered to activate the PDU session user plane, the AMF may include at least one N2 SM information received from the SMF in the N2 request. When there is additional N2 SM information received from the SMF, the AMF may include and transmit the additional N2 SM information received from the SMF in a separate N2 message (eg, N2 tunnel setup request). Alternatively, when a plurality of SMFs are involved, after all Nsmf_PDUSession_UpdateSMContext response service operations related to the UE are received from the SMF, the AMF may transmit one N2 request message to the (R)AN.

When the NG-RAN node provides a list of recommended cells/TAs/NG-RAN node identifiers during the AN release procedure, the AMF will include the list of recommended cells/TAs/NG-RAN node identifiers in the N2 request. I can. When the NG-RAN decides to enable the RRC inactive state for the UE, the NG-RAN can use this information to allocate the RAN Notification Area.

AMF based on network configuration may include "RRC Inactive Assistance Information" of the UE in the N2 request.

If possible, the AMF may include UE radio capability information in the N2 request and transmit it to the NG-RAN node.

13) Signaling from (R)AN to UE: The NG-RAN may perform RRC Connection Reconfiguration with the UE. Specifically, the NG-RAN may perform RRC connection reconfiguration with the UE according to Qos information for all QoS flows of a data radio bearer and a PDU session in which the UP connection is activated. For the UE that was in the CM-IDLE state, if the service request is not triggered only for the signaling connection by the UE, user plane security can be established in this step. For the UE in the CM-IDLE state, when a service request is triggered only for signaling connection by the UE, the AS security context may be established in this step.

If the N2 request includes a NAS message, the NG-RAN can deliver the NAS message to the UE. The UE deletes the context of the PDU session that is not available in 5GC locally.

NOTE 2: The reception of the service acceptance message may not mean that the user plane radio resource has been successfully activated.

After the user plane radio resource is set up, the uplink data from the UE can now be delivered to the NG-RAN. The NG-RAN may transmit uplink data to the UPF address and tunnel ID provided in step 11.

14) [Conditional Operation] Signaling from (R)AN to AMF: (R)AN may transmit confirmation of N2 request to AMF. For example, (R)AN may transmit an N2 request Ack to the AMF. Here, the N2 request Ack is N2 SM information (AN tunnel information, a list of accepted QoS Flows for the PDU Sessions whose UP connections are activated) and UP connection is activated. It may include a list of rejected QoS flows of the PDU session (including a List of rejected QoS Flows for the PDU Sessions whose UP connections are activated) and a PDU session ID.

The message including the N2 request Ack may include N2 SM information (eg, AN tunnel information). When the AMF transmits a separate N2 message in step 11, the NG-RAN may respond to N2 SM information with a separate N2 message.

When a plurality of N2 SM messages are included in the N2 request message of step 12, the N2 request Ack may include a plurality of N2 SM information and information enabling the AMF to associate a response with a related SMF.

15) [Conditional Operation] Signaling from AMF to SMF: The AMF may transmit an Nsmf_PDUSession_UpdateSMContext request (including N2 SM information, RAT type, and access type) per PDU session to the SMF. The AMF may determine the access type and the RAT type based on the global RAN node ID associated with the N2 interface.

When the AMF receives the N2 SM information (one or more) in step 14, the AMF may deliver the N2 SM information to the related SMF per PDU session ID. When the UE time zone is changed compared to the previously reported UE time zone, the AMF may include the UE time zone IE (Information Element) in the Nsmf_PDUSession_UpdateSMContext request.

16) [Optional operation] Signaling from the SMF to the PCF: When a dynamic PCC is distributed, the SMF may initiate a notification about new location information to the PCF (if subscribed) by performing the SMF initiated SM policy modification procedure. The PCF can provide updated policies.

17a) [Conditional operation] Signaling from the SMF to the new I-UPF: The SMF may transmit an N4 session modification request to the new I-UPF. The N4 session modification request may include AN tunnel information and a list of accepted QFIs.

When the SMF selects a new SMF to operate as an I-UPF for a PDU session in step 5, the SMF may initiate an N4 session modification procedure for the new I-UPF and provide AN tunnel information. Downlink data from the new I-UPF can be delivered to the NG-RAN and UE.

17b) [Conditional operation] Signaling from UPF to SMF: The UPF may transmit an N4 session modification response to the SMF.

18a) [Conditional operation] Signaling from SMF to UPF (PSA): The SMF may transmit an N4 session modification request to UPF (PSA). The N4 session modification request may include AN tunnel information and a list of rejected QoS flows.

When the user plane is set up or modified, and when there is no I-UPF after modification, the SMF may initiate an N4 session modification procedure for UPF (PSA) and provide AN tunnel information. Downlink data from UPF (PSA) can now be delivered to the NG-RAN and UE.

For QoS flows in the list of rejected QoS flows, the SMF may instruct the UPF to remove rules (eg, packet detection rules, etc.) related to the corresponding QoS flow.

18b) [Conditional operation] Signaling from UPF to SMF: The UPF may transmit an N4 session modification response to the SMF.

19) [Conditional operation] Signaling from SMF to AMF: The SMF may transmit an Nsmf_PDUSession_UpdateSMContext response to the AMF.

20a) [Conditional operation] Signaling from SMF to a new UPF (or I-UPF): The SMF may transmit an N4 session modification request to a new UPF (or I-UPF).

When the forwarding tunnel is established for a new I-UPF and when the timer set by the SMF for the forwarding tunnel in step 8a expires, the SMF releases the forwarding tunnel to a new UPF (or I-UPF) acting as an N3 endpoint. In order to do so, an N4 session modification request can be sent.

20b) [Conditional operation] Signaling from a new UPF (or I-UPF) to the SMF: The new UPF (or I-UPF) may transmit an N4 session modification response to the SMF.

A new UPF (or I-UPF) N4 session modification response acting as an N3 endpoint may be transmitted to the SMF.

21a) [Conditional operation] Signaling from SMF to UPF (PSA): The SMF may transmit an N4 session modification request to UPF (PSA).

When the forwarding tunnel is established for the UPF (PSA) and when the timer set by the SMF for the forwarding tunnel in step 7b has expired, the SMF sends an N4 session to the UPF (PSA) acting as an N3 endpoint to release the forwarding tunnel. You can send a modification request.

21b) [Conditional operation] Signaling from UPF (PSA) to SMF: The UPF (PSA) may transmit an N4 session modification response to the SMF.

The UPF (PSA) operating as an N3 endpoint may transmit an N4 session modification response to the SMF.

22a) [Conditional operation] Signaling from the SMF to the previous UPF: The SMF may transmit an N4 session modification request or an N4 session release request to the previous UPF.

If the SMF decides to continue using the previous UPF in step 5, the SMF may transmit an N4 session modification request to the previous UPF and provide AN tunnel information.

If the SMF selects a new UPF operating as an I-UPF in step 5 and the previous UPF is not a PSA UPF, after the timer in step 6b or 7b expires, it transfers the N4 session release request (including the cause of release). By transmitting to the I-UPF of SMF can initiate resource release (resource release).

22b) Signaling from the previous I-UPF to the SMF: The previous I-UPF may transmit an N4 session modification response or an N4 session release response to the SMF.

The previous UPF confirms the modification or release of resources through an N4 session modification response or an N4 session release response.

An example of a UE initiated service request procedure is the same as steps 1 to 22b described above.

For mobility related events, the AMF may call the Namf_EventExposure_Notify service operation after step 4.

When Namf_EventExposure_Notify is received with an indication that the UE is reachable, when the SMF has pending DL data, the SMF performs the Namf_Communication_N1N2MessageTransfer service operation on the AMF in order to establish a user plane for the PDU session. Can be called. In other cases, the SMF may resume transmitting the DL data notification to the AMF in the case of DL data.

Degree 8 is A signal flow diagram illustrating an exemplary network initiation service request procedure.

Network initiated service request procedure is the network signaling with the UE (e.g., N1 signaling to the UE, short message service (SMS) to be received by the UE (mobile-terminated), mobile terminating: the destination of data is the UE) It is used when it is necessary to activate the user plane for a PDU session to deliver user data.

When the network initiated service request procedure is triggered by SMSF (Short Message Service Function), PCF, LMF (Location Management Function), GMLC (Gateway Mobile Location Center), NEF or UDM, in FIG. 8, SMF is the corresponding NF. Can be replaced. For example, when the network initiation service request procedure is triggered by the PCF, the PCF may perform operations performed by the SMF of FIG. 8.

When the UE is in the CM-IDLE state or the CM-CONNECTED state in 3GPP access, the network initiates a network service request procedure.

When the UE is in the CM-IDL state and asynchronous type communication is not activated, the network may transmit a paging request to the (R)AN/UE. The paging request triggers a UE initiated service request procedure in the UE. When asynchronous type communication is activated, the network stores the received message, and when the UE enters the CM-CONNECTED state, the received message may be delivered to the (R)AN and/or the UE.

When the UE is in the CM-IDLE state in non-3GPP access, and the UE is simultaneously registered for 3GPP access and non-3GPP access in one public land mobile network (PLMN), the network performs the network initiation service request procedure for 3GPP access. It can be initiated through.

When the UE is in the CM-IDLE state in 3GPP access, in the CM-CONNECTED state in non-3GPP access, and the UE is simultaneously registered for 3GPP access and non-3GPP access in one PLMN, the network provides non-3GPP access. Through the network initiation service request procedure can be initiated.

In the network initiated service request procedure, both SMF and UPF belong to the PLMN serving the UE. For example, in the home routed roaming case, the SMF and UPF of the HPLMN are not affected by the service request procedure (that is, the SMF and UPF of the HPLMN are not involved in the service request procedure).

The procedure of FIG. 8 deals with a non exhaustive list of use-cases for 3GPP access as follows (detailed conditions under which each step applies are described in the procedure below):

-When the SMF needs to set up an N3 tunnel in order to deliver a downlink packet for a PDU session to the UE, and the UE is in CM-IDLE state: Step 3a includes an N2 message, and step 4b (paging) is Can be done.

-When SMF needs to set up an N3 tunnel in order to deliver a downlink packet for a PDU session to the UE, and the UE is in a CM-CONNECTED state: Step 3a includes an N2 message, and step 4a (UP activation) Can be performed.

-If NF (e.g., SMF, SMSF, LMF or NEF) needs to transmit an N1 message to the UE, and the UE is in CM-IDLE state: Step 3a includes an N1 message, and step 3b is the cause "to the UE. Attempting to reach (Attempting to reach UE)" is included, and step 4b (paging) occurs.

-NF (e.g., SMSF, PCF, UDM) triggers the AMF to establish a NAS connection with the UE, and the UE is in the CM-IDLE state: The trigger varies depending on the procedure, and step 4b (paging) occurs.

1) When the UPF receives downlink data for a PDU session and AN tunnel information for a PDU session is not stored in the UPF, the UPF buffers the downlink data based on an instruction received from the SMF. Alternatively, downlink data can be delivered to the SMF.

2a) Signaling from the UPF to the SMF: The UPF may transmit a data notification to the SMF. The data notification may include information for identifying the QoS flow for the N4 session ID and DL data packet, and DSCP.

-When the first downlink data for an arbitrary QoS flow arrives, if the SMF has not previously informed the UPF not to transmit the data notification to the SMF, the UPF may transmit a data notification message to the SMF. For reference, if the SMF previously informs the UPF not to transmit the data notification to the SMF, subsequent steps may be omitted.

-When the UPF receives a downlink data packet for another QoS flow in the same PDU session, the UPF may transmit another data notification message to the SMF.

-When the Paging Policy Differentiation feature is supported by UPF and when the PDU session type is IP, UPF is a type of service (TOS) received from the IP header of the downlink data packet (IPv4)/ Information for identifying QoS flows for DSCP and DL data packets having a TC (Traffic Class) (IPv6) value may be included in the data notification.

2b) Signaling from SMF to UPF: Data notification Ack can be transmitted.

2c) When the SMF instructs the UPF that it will buffer the data packet, the UPF can deliver the downlink data packet to the SMF.

-When the Paging Policy Differentiation feature is supported by the SMF, the SMF receives the Paging Policy Indication from the IP header of the downlink data packet TOS (IPv4)/TC (IPv6). ) Is determined based on the value of DSCP, and the QFI of the QoS flow for the DL data packet can be identified.

3a) [Conditional operation] i) Signaling from SMF to AMF: SMF is Namf_Communication_N1N2MessageTransfer (SUPI, PDU session ID, N2 SM information (QFI(s), QoS profile(s), CN N3 tunnel information, S-NSSAI and paging policy) Indication), Area of validity for N2 SM information, ARP ((Allocation and Retention Priority), paging policy indication, 5QI and N1N2TransferFailure notification target address included) Or, ii) NF to AMF signaling: NF may transmit Namf_Communication_N1N2MessageTransfer (including SUPI and N1 messages) to AMF.

Upon receiving the data notification message, for the PDU session corresponding to the LADN, the SMF may perform an operation to support the LADN. The SMF may notify the UPF that transmitted the data notification to discard downlink data for the PDU session and/or not to provide an additional data notification message.

In other cases, the SMF may determine whether to contact the AMF (whether to contact). The SMF may not contact the AMF in the following cases:

-If the SMF has previously notified that the UE is unreachable; or

-When the UE is reachable only for a regulatory prioritized service, and the PDU session is not a regulatory priority service.

The SMF determines the AMF, and the SMF includes the PDU session ID derived from the N4 session ID received in step 2a, so that Namf_Communication_N1N2MessageTransfer may be called to the AMF.

While waiting for the user plane connection to be activated, if the SMF receives any additional data notification message or downlink data packet, a higher priority than the prior data notification message or downlink data packet related priority (e.g., ARP When the SMF buffers the data packet for the QoS flow related to the priority level), the SMF may call a new Namf_Communication_N1N2MessageTransfer indicating a higher priority ARP and PDU session ID to the AMF.

While waiting for the user plane connection to be activated, if the SMF receives a message from a new AMF (not the AMF that SMF previously called theNamf_Communication_N1N2MessageTransfer), the SMF will re-invoke Namf_Communication_N1N2MessageTransfer to the new AMF. I can.

When supporting paging policy differentiation, the SMF is a paging policy related to the 5QI related to QFI in step 2a, the packet received in step 2c, downlink data received from ARP or UPF, or downlink data that triggered a data notification message within Namf_Communication_N1N2MessageTransfer. Can indicate an indication.

NOTE 1: AMF sends a request message to perform signaling to the UE/RAN (e.g., network-initiated deregistration, SMF initiated PDU session modification, etc.) from other network functions (Network Function: NF). Can receive. When the UE is in the CM-CONNECTED state and the AMF delivers only the N1 message to the UE, the flow continues at step 6 below.

N2 SM information is optional. For example, when the SMF intends to transmit a PDU session modification command only to update the UE to the PCO, N2 SM information may be optional.

3b) [Conditional Action] The AMF can respond to the SMF.

If the UE is in the CM-IDLE state for AMF, and the AMF can page the UE, the AMF may immediately transmit to the SMF with a Namf_Communication_N1N2MessageTransfer response "attempt to reach the UE (Attempting to reach UE)". Cause "Attempting to reach UE" means that the N2 SM information provided in step 3a to the SMF can be ignored by the AMF if the UE is reachable, and the SMF will be requested to provide the N2 SM information again. It can indicate that you can.

While waiting for the UE to respond to the previous paging request, when the AMF receives a Namf_Communication_N1N2MessageTransfer request message having the same priority or lower priority as the previous message triggering paging, or the AMF is based on the local policy, this UE When it is determined not to trigger an additional paging request for, AMF may reject the Namf_Communication_N1N2MessageTransfer request message.

When the UE is in the CM-CONNETED state in the AMF, the AMF may immediately transmit a Namf_Communication_N1N2MessageTransfer response to the SMF with the cause of "N1/N2 transfer success".

When the UE is in the CM-IDLE state and the AMF determines that the UE is not reachable for paging, the AMF may transmit a Namf_Communication_N1N2MessageTransfer response to SMF or other network functions (the NF that transmitted the request message to the AMF in step 3a). have. Alternatively, the AMF may perform asynchronous type communication and store the UE context based on the received messaging. When asynchronous type communication is called, when the UE is reachable (eg, when the UE enters the CM-CONNECTED state), the AMF may initiate communication with the UE and the (R)AN.

When the AMF determines that the UE is not reachable for SMF (e.g., as the UE is in Mobile Initiated Connection Only (MICO) mode, or the UE is registered only through non-3GPP access, the state of the UE is CM- IDLE), the AMF may reject the request from the SMF. When the SMF does not subscribe to the event of UE reachability, the AMF may include an indication in the rejection message (indication that the SMF does not need to trigger a Namf_Communication_N1N2MessageTransfer request for AMF). The AMF may store an indication that the SMF has been informed that the UE is not reachable.

If the UE is not in MICO mode and the AMF detects that the UE is in a Non-Allowed Area, the AMF sends a request from the SMF unless the request from the SMF is for a regulation priority service. It can refuse and notify the SMF that the UE is only reachable for regulatory priority service. The AMF may store an indication that the SMF has been informed that the UE is only reachable for regulatory priority services.

When the previous AMF receives Namf_Communication_N1N2MessageTransfer, when a registration procedure with AMF change is in progress, the previous AMF may reject the request with an indication that Namf_Communication_N1N2MessageTransfer has been temporarily rejected.

When a Namf_Communication_N1N2MessageTransfer response is received with an indication that the request has been temporarily rejected, the SMF starts a locally set guard timer and can wait until a random message comes from the AMF. When a message from the AMF is received, the SMF may re-call Namf_Communication_N1N2MessageTransfer (with N2 SM information) to the AMF that transmitted the message. In other cases, the SMF may proceed to step 3a when the guard timer expires. If the SMF determines that control region buffering is applied, the SMF may request the UPF to start transmitting the downlink data PDU to the SMF.

3c) [Conditional operation] SMF can respond to UPF. For example, the SMF may transmit a failure indication to the UPF.

The SMF may notify the UPF of a user plane setup failure.

When the SMF receives an indication that the UE is not reachable from the AMF or the indication that the UE is reachable only for the regulation priority service, the SMF may perform the following operation based on the network policy:

-The SMF may instruct the UPF to stop sending data notifications;

-SMF may instruct the UPF to stop buffering the DL data and discard the buffered data;

-SMF may instruct the UPF to stop sending data notifications, stop buffering DL data, and discard the buffered data; or

-While the UE is not reachable, the SMF suppresses transmitting an additional Namf_Communication_N1N2MessageTransfer message for DL data.

Based on the operator's policy, the SMF may apply suspension of the charging procedure.

When the SMF receives an indication from the AMF that the Namf_Communication_N1N2MessageTransfer requested by the SMF has been temporarily rejected, the SMF may instruct the UPF to apply temporary buffering based on the network policy.

4a) [Conditional operation] When the UE is in the CM-CONNECTED state in the access related to the PDU session ID received from the SMF in step 3a, steps 12 to 22 of FIGS. 7A to 7C to activate the user plane connection to the PDU session A (R) can be performed without transmitting a paging message to the AN node and the UE (eg, it is possible to establish a radio resource and an N3 tunnel). In step 12 of FIGS. 7A to 7C, the AMF may not transmit a NAS service acceptance message to the UE. Parts other than steps 12 to 22 of FIGS. 7A to 7C may be omitted.

4b) [Conditional operation] Even if the UE is in the CM-IDLE state in 3GPP access, the PDU session ID received from the SMF in step 3a is associated with the 3GPP access, and the UE is in the CM-CONNECTED state for non-3GPP access If the AMF decides to notify the UE through 3GPP access based on the policy, the AMF may transmit a paging message to the NG-RAN node through 3GPP access.

When the UE is simultaneously registered through 3GPP access and non-3GPP access in the same PLMN, the UE is in CM-IDLE state in 3GPP access and non-3GPP access mode, and the PDU session ID of step 3a is related to non-3GPP access , AMF may transmit a paging message related to access "non-3GPP" to the NG-RAN node through 3GPP access.

When the UE is in RM (Registration Management)-REGISTERED state and CM-IDLE state, and the UE is reachable in 3GPP access, AMF is a paging message (NAS ID for paging, registration area list, paging DRX length) , Paging Priority indication and PDU session-related access (including access associated to the PDU Session) can be transmitted to the (R)AN node belonging to the registration area in which the UE is registered have. When a paging message is received from the AMF, the NG-RAN node may page the UE by including access related to the PDU session in the paging message.

For reference, in order to reflect the registration state of the UE in the PLMN, two RM states of the RM-DEREGISTERED state and the RM-REGISTERED state are used within the UE and AMF.

When supporting paging policy differentiation, the paging strategy can be set in the AMF for different combinations of DNN, paging policy indication, ARP and 5QI.

For the RRC_INACTIVE state, the paging strategy can be set in (R)AN for other combinations of paging policy indication, ARP and 5QI.

The paging priority indication can only be included in the following cases:

-When AMF receives a Namf_Communication_N1N2MessageTransfe message containing ARP values related to priority services (eg, MPS, MCS) set by the operator.

-One paging priority level can be used for multiple ARP values. Mapping of the ARP value to the paging priority level may be set in the AMF and NG-RAN according to the operator policy.

The (R)AN may prioritize paging of the UE according to the paging priority indication (or paging policy indicator).

Namf_Communication_N1N2MessageTransfer message indicating the ARP value related to the priority service (e.g., MPS, MCS) set by the operator while the AMF waits for a response from the UE to the paging request message transmitted without a paging priority indication (or paging policy indicator) When receiving, the AMF may transmit another paging message with an appropriate paging priority (or paging policy indicator). For a Namf_Communication_N1N2MessageTransfer message received later having the same priority or higher priority, the AMF may determine whether to transmit a paging message with an appropriate paging priority based on a local policy.

Paging stratategies can include:

-Paging retransmission scheme (eg, how often paging is repeated or at what time interval paging is repeated);

-Determine whether to transmit a paging message to the (R)AN node during specific AMF high load conditions;

-Whether to apply sub-area-based paging (e.g., the first paging from the last known cell-id or TA and retransmission from all registered TAs)

NOTE 2: Setting the paging priority (or paging policy indicator) in the paging message is independent of any paging strategy.

In order to reduce the signaling load and network resources used to successfully paging the UE, AMF and (R)AN may support additional paging optimization using at least one or more of the following means:

-By AMF implementing specific paging strategies (eg, AMF can send an N2 paging message to the (R)AN node that has recently served the UE);

-By AMF taking into account information on recommended cells and NG-RAN nodes provided by (R)AN when switching to CM-IDLE state (Information On Recommended Cells And NG-RAN nodes). The AMF may determine the (R)AN node to be paged in consideration of the (R)AN node-related part of the information, and provide the information on the recommended cells to each of the (R)AN nodes by including the information on the N2 paging message. have;

-By (R)AN taking into account Paging Attempt Count Information provided by AMF in paging.

When the UE radio capability for paging information is available in the AMF, the AMF may include the UE radio capability for paging information in the N2 paging message and transmit it to the (R)AN node.

When information on recommended cells and NG-RAN nodes are available in the AMF, the AMF determines the (R)AN node for paging in consideration of the information, and when paging the (R)AN node, the AMF is The information on the recommended cell may be transparently transmitted to the (R)AN node.

The AMF may include paging attempt count information in the N2 paging message. The paging attempt count information may be the same for all (R)ANs selected for paging by the AMF.

4c) [Conditional operation] When the UE is simultaneously registered for 3GPP access and non-3GPP access in the same PLMN, the UE is in a CM-CONNECTED state in 3GPP access, and the PDU session ID of step 3a is related to non-3GPP access, AMF May transmit a NAS notification message including a non-3GPP access type to the UE through 3GPP access and set a notification timer. When step 4c is performed, step 5 may be omitted.

The UE is simultaneously registered for 3GPP access and non-3GPP access in the same PLMN, the UE is in CM-IDL state in 3GPP access and CM-CONNECTED state in non-3GPP access, and the PDU session ID of step 3a is associated with 3GPP access. , If the AMF decides to notify the UE through the non-3GPP access based on the local policy, the AMF transmits a NAS notification message including the 3GPP access type to the UE through the non-3GPP access, and can set a notification timer. have.

5) [Conditional operation] Signaling from AMF to SMF: The AMF may transmit a notification related to the failure of Namf_Communication_N1N2Transfer to the SMF. For example, the AMF may transmit a Namf_Communication_N1N2TransferFailure notification to the SMF.

The AMF uses a timer to supervise the paging procedure. If the AMF does not receive a response from the UE to the paging request message, the AMF may apply additional paging according to any available paging strategy described in step 4b.

If the UE does not respond to paging, the AMF will notify the SMF by sending a Namf_Communications_N1N2MessageTransfer Failure notification to the notification target address provided by the SMF in step 3a, unless the AMF is aware of the ongoing MM procedure that prevents the UE from responding. I can. Here, the case where the AMF recognizes the ongoing MM procedure that prevents the UE from responding may be, for example, a case where the AMF receives the N14 context request message indicating that the UE performs a registration procedure with another AMF.

When the Namf_Communication_N1N2TransferFailure notification is received, the SMF may notify the UPF.

6) When the UE is in the CM-IDLE state in 3GPP access, upon receiving a paging request for a PDU session related to 3GPP access, the UE may initiate the UE initiated service request procedure described in FIGS. 7A to 7C. In step 4 of FIG. 7A, the AMF may call the Nsmf_PDUSession_UpdateSMContext request associated with the PDU session identified in the service request message (excluding the PDU session for the PDU session ID included in Namf_Communication_N1N2MessageTransfe in step 3a of FIG. 8) to the SMF. . To support the transfer of buffered data, the SMF may instruct the UPF to establish a data transfer tunnel between the old UPF and the new UPF or PSA as described in steps 6a, 7a, and 8b of FIG. 7A.

When the UE is in CM-IDLE state in both non-3GPP access and 3GPP access, and receives a paging request for a PDU session related to non-3GPP access, the UE initiates the UE initiated service request procedure described in FIGS. 7A to 7C. I can. Here, the UE initiated service request procedure includes a list of allowed PDU sessions that can be re-activated through 3GPP access according to the UE policy and whether the S-NSSAI of this PDU session is included in the allowed NSSAI for 3GPP access. Can include. In case there is no PDU session that can be re-activated through 3GPP access, the UE may contain a list of empty allowed PDU sessions. When the AMF receives a service request message from the UE through the non-3GPP access (e.g., due to the UE successfully connecting to the non-3GPP access), the AMF may stop the paging procedure and process the received service request procedure. have. When the AMF receives the service request message and the list of allowed PDU sessions provided by the UE does not include the PDU session for the UE that has been paged, the AMF calls the Namf_EventExposure_Notify service, so that the UE can reach the PDU session again. -You can notify the SMF that you have not accepted the activation.

When the UE is in the CM-IDLE state in non-3GPP access and in the CM-CONNECTED state in 3GPP access, upon receiving a NAS notification message including a non-3GPP access type through 3GPP access, the UE is in FIGS. The UE initiated service request procedure described in 7c may be initiated. Here, the UE initiated service request procedure includes a list of allowed PDU sessions that can be re-activated through 3GPP access according to the UE policy and whether the S-NSSAI of this PDU session is included in the allowed NSSAI for 3GPP access. Can include. If there is no PDU session that can be re-activated through 3GPP access, the UE may include a list of empty allowed PDU sessions. When the AMF receives the service request message and the list of allowed PDU sessions provided by the UE does not include a PDU session for the UE that has been notified, the AMF calls the Namf_EventExposure_Notify service so that the UE can reach However, it is possible to notify the SMF that the re-activation of the PDU session has not been accepted. When the AMF receives a service request message from the UE through non-3GPP access, the AMF may stop the notification timer and process the received service request procedure.

When the UE is in the CM-IDLE state in 3GPP access and in the CM-CONNECTED state in non-3GPP access, upon receiving the NAS notification identifying the 3GPP access type through the non-3GPP access, the UE if 3GPP access is available, The UE initiated service request procedure described in FIGS. 7A to 7C may be initiated through 3GPP access. If the AMF does not receive the service request message before the notification timer expires, the AMF may page the UE through 3GPP access or notify the SMF that the UE was unable to re-activate the PDU session.

7) UPF can transmit buffered downlink data to the UE through the (R)AN node that has performed the service request procedure.

The network may transmit downlink signaling when the network initiation service request procedure is initiated due to a request from another network described in step 3a.

<Connection Management Mangement : CM)>

CM is used to establish or release a signaling connection between the UE and the AMF. For example, the CM includes a function of establishing and releasing a NAS signaling connection between the UE and the AMF through the N1 reference point. The NAS signaling connection enables NAS signaling exchange between the UE and the core network.

The NAS signaling connection may include AN signaling connection between AN (Access Network) and UE (RRC connection through 3GPP access or connection between UE and N3IWF through non-3GPP access) and N2 connection between AN and AMF for UE. .

The two CM states are used to reflect the NAS signaling connection between the UE and AMF. The two CM states are:

-CM-IDLE

-CM-CONNECTED

The CM state for 3GPP access and the CM state for non-3GPP access may be independent of each other. For example, it may be in a CM-IDLE state for 3GPP access and a CM-CONNECTED state for non-3GPP access.

Hereinafter, the CM-IDLE state, the CM-CONNECTED state, and the conversion between the CM-IDLE state and the CM-CONNECTED state will be described.

1. CM-IDLE status

A UE in CM-IDLE state does not have a NAS signaling connection with AMF through the N1 interface. The UE may perform a cell selection or cell reselection procedure and a PLMN selection procedure.

For the UE in the CM-IDLE state, there are no AN signaling connection, N2 connection, and N3 connection. When the UE is in the CM-IDLE state and RM (Registration Management)-REGISTERED state, the UE may perform the following operations:

-Unless the UE is in Mobile Initiated Connection Only (MICO) mode, it can respond to paging by performing a service request procedure.

-When the UE has uplink signaling or user data to transmit, a service request procedure can be performed.

If the UE state in the AMF is RM-REGISTERED, UE information for initiating communication with the UE may be stored in the AMF. The AMF may use a 5G-GUTI (Globally Unique Temporary Identifier) to search for stored information necessary to initiate communication with the UE.

The UE may provide 5G-S-TMSI (5G-Short-Temporary Mobile Subscriber Identity) as part of the AN parameter while performing a procedure for establishing an AN signaling connection. Whenever an AN signaling connection is established between the UE and the AN (when entering the RRC Connected state through 3GPP access, or establishing a connection between the UE and N3IWF through non-3GPP access), the UE is in the CM-CONNECTED state. Can enter.

Transmission of the initial NAS message initiates the transition from the CM-IDLE state to the CM-CONNECTED state. Here, the initial NAS message may be, for example, a registration request message, a service request message, and a Deregistration Request message.

When the UE state in the AMF is CM-IDLE and RM-REGISTERED, the AMF may perform the following entrustment:

-When the AMF has mobile-terminated data or signaling to be transmitted to the UE, the AMF may perform a network triggered service request procedure by transmitting a paging request message to the UE. The AMF may perform a network initiated service request procedure except when the UE cannot respond due to MICO mode or mobility limitation.

Whenever an N2 connection is established between the AN and the AMF for the UE, the AMF may enter the CM-CONNECTED state for the UE. Receiving an initial N2 message (eg, N2 INITIAL UE MESSAGE) initiates a transition from the CM-IDLE state to the CM-CONNECTED state in the AMF.

When the UE and AMF are in the CM-IDLE state, for example, by activating the MICO mode, power efficiency and signaling efficiency may be optimized.

2. CM-CONNECTED status

The UE in the CM-CONNECTED state has a signaling connection with AMF through the N1 reference point. The NAS signaling connection may use an RRC connection between a UE and an NG-RAN and a New Generation Application Protocol (NGAP) UE association between an AN and AMF for 3GPP. The UE may be in a CM-CONNECTED state with an NGAP UE association not bound to any Transport Network Layer Association (TNLA) between AN and AMF. When the NAS signaling procedure is completed, the AMF may decide to release the NAS signaling connection with the UE.

In the CM-CONNECTED state, the UE can perform the following operations:

-Whenever the AN signaling connection is released (e.g., when entering the RRC Idle state through 3GPP access or when it is detected by the UE that the connection between the UE and N3IWF through non-3GPP access is released), the UE You can enter the CM-IDLE state.

When the UE CM state in the AMF is the CM-CONNECTED state, the AMF may perform the following operations:

-When the AN release procedure is completed, when the logical NGAP signaling connection to the UE and the N3 user plane connection are released, the AMF may enter the CM-IDLE state for the UE.

Until the UE is de-registered from the core network, the AMF may maintain the UE CM state in the AMF in the CM-CONNECTED state.

The UE in the CM-CONNECTED state may be in the RRC deactivated state. When the UE is in the RRC deactivated state, the following applies:

-UE reachability is managed by the RAN, along with assistance information from the core network,

-UE paging is managed by the RAN.

-The UE manages paging using the UE's CN (5G-S-TMSI) and RAN indentifier

3. Conversion between CM-IDLE state and CM-CONNECTED state

An example of switching between the CM-IDLE state and the CM-CONNECTED state will be described based on the description of the CM-IDLE state and the CM-CONNECTED state described above.

When the CM state in the UE is the CM-IDLE state, when an AN signaling connection is established (eg, when the UE transmits an initial NAS message), the CM state is switched to the CM-CONNECTED state. When the CM state in the UE is the CM-CONNECTED state, when the AN signaling connection is released, the CM state is switched to the CM-IDLE state.

When the CM state for the UE in the AMF is the CM-IDLE state, when the N2 context is established, the CM state is switched to the CM-CONNECTED state. When the CM state for the UE in the AMF is the CM-CONNECTED state, when the N2 context is released, the CM state is switched to the CM-IDLE state.

<RRC state>

In LTE, the RRC state includes an RRC_IDLE state and an RRC_CONNECTED state. In 5G, the RRC state may include an RRC_IDLE state, an RRC_CONNECTED state, and an RRC_INACTIVE state. That is, the RRC_INACTIVE state has been newly defined in 5G.

The RRC_INACTIVE state may refer to an RRC state in which the terminal (eg, the UE) is in a connected state in the core network, but is an IDLE state in terms of radio between the terminal and the NG-RAN. For example, when the terminal is in the RRC_INACTIVE state, the terminal is in a state in which the RRC connection is released from the side of the radio, the terminal is in a state of MM (Mobility Management)-REGISTERED from the side of the core network, and may be in the CM (Connection Management)_CONNECTED state. .

When the RRC_INACTIVE state is used, when the terminal is switched from the RRC_INACTIVE state to the RRC_CONNECTED state, the core can provide a connection to the terminal quickly without the need for signaling that occurs when switching to the CONNECTED state. In addition, since it is possible to prevent unnecessary waste of radio resources in the aspect of radio between the terminal and the NG-RAN, radio resources can be efficiently used.

Hereinafter, a procedure for the UE to switch from the RRC_IDLE state to the RRC_CONNECTED state will be described with reference to FIG. 9, and the procedure for the UE to switch from the RRC_INACTIVE state to the RRC_CONNECTED state will be described with reference to FIG.

9 shows the terminal Triggered A diagram showing an example of a procedure for switching from RRC_IDLE to RRC_CONNECTED.

An example of a procedure for changing the RRC state of the UE from the RRC_IDLE state to the RRC_CONNECTED state will be described with reference to FIG. 9. That is, UE triggered transition from RRC_IDLE to RRC_CONNECTED will be described.

In the example of FIG. 9, a terminal (eg, UE) may be in an RRC_IDLE state and a CM-IDLE state.

1) The UE may transmit a request to set up a new connection to the gNB in the RRC_IDLE state. For example, the UE may transmit an RRC setup request message (RRCSetupRequest message) to the gNB.

2 and 2a) The gNB may complete the RRC setup procedure. For example, the gNB may transmit an RRC setup message (eg, RRCSetup message) to the UE. Upon receiving the RRCSetup message from the gNB, the UE may enter the RRC_CONNECTED state. The UE may transmit an RRC setup complete message (eg, RRCSetupComplete message) to the gNB. The RRC setup complete message (eg, RRCSetupComplete message) may include a NAS message transmitted by the UE.

3) The first NAS message from the UE piggybacked in the RRC setup completion message (eg, RRCSetupComplete message) may be transmitted to the AMF. For example, the gNB may transmit an initial UE message (eg, INITIAL UE MESSAGE) including a NAS message transmitted by the UE to the AMF.

4, 4a, 5 and 5a) Additional NAS messages may be exchanged between the UE and the AMF. For example, the NAS may send a DOWNLINK NAS TRANSPORT message to the gNB. Then, the gNB may transmit a downlink information transfer message (eg, a DLInformationTransfer message) to the UE. The UE may transmit an uplink information delivery message (eg, ULInformationTransfer message) to the gNB to the gNB. Then, the gNB can transmit the UPLINK NAS TRASNPORT message to the AMF.

6) AMF may prepare UE context data. The UE context data may include information on a PDU session context, a security key, a UE radio capability, a UE security capability, and the like. In addition, the AMF may transmit an initial context setup request message (eg, INITIAL CONTEXT SETUP REQUEST message) including UE context data to the gNB.

7 and 7a) gNB can activate AS security with the UE. For example, the gNB may transmit a security mode command message (SecurityModeCommand message) to the UE. Then, the UE may transmit a security mode complete message (SecurityModeComplete message) to the gNB.

8 and 8a) The gNB may perform a reconfiguration to set up Signaling Radio Bearer 2 (SRB2) and Data Radio Bearers (DRB). For example, the gNB may transmit an RRC reconfiguration message (eg, an RRCReconfiguration message) to U)E. Then, the UE may transmit an RRC reconfiguration complete message (eg, an RRCReconfigurationComplete message) to the gNB.

9) The gNB may inform the AMF that the setup procedure is complete. For example, the gNB may transmit an initial context setup response message (eg, INITIAL CONTEXT SETUP RESPONSE message) to the AMF.

For reference, the RRC messages of step 1 and step 2 may use SRB0, and all subsequent messages may use SRB1. The messages of step 7 and step 7A may be integrity protected. From step 8, all messages can be integrity protected and can be ciphered.

In the case of a signaling-only connection, since SRB2 and DRB are not set up, step 8 may be omitted.

10 shows the terminal Triggered This is a diagram showing an example of a procedure for switching from RRC_INACTIVE to RRC_CONNECTED.

An example of a procedure for changing the RRC state of the terminal from the RRC_INACTIVE state to the RRC_CONNECTED state will be described with reference to FIG. 10. That is, UE triggered transition from RRC_INACTIVE to RRC_CONNECTED will be described.

In the example of FIG. 10, a terminal (eg, a UE) may be in an RRC_INACTIVE state and a CM-CONNECTED state.

For reference, the example of FIG. 10 may represent an example of a procedure for switching the RRC state of the terminal from the RRC_INACTIVE state to the RRC_CONNECTED state when the UE context retrieval is successful.

1) In the RRC_INACTIVE state, the terminal may resume the RRC connection with the network (resume). For example, the terminal may transmit an RRC resume request message (eg, RRCResumeRequest message) to the gNB. The RRC resume request message (eg, RRCResumeRequest message) may include an Inactive Radio Network Temporary Identifier (I-RNTI) allocated by the last serving gNB (gNB).

2) When the gNB can resolve the gNB ID (identity) included in the I-RNITI, it may request the last serving gNB to provide UE context data. For example, the gNB may transmit a UE context search request message (eg, a RETRIEVE UE CONTEXT REQUEST message) to the last serving gNB. Then, the last serving gNB may transmit a UE context search response message (eg, RETRIEVE UE CONTEXT RESPONSE message) to the gNB. The UE context search response message (eg, RETRIEVE UE CONTEXT RESPONSE message) transmitted by the last serving gNB may include UE context data.

4 and 5) The gNB and the UE can complete the resumption of the RRR connection. For example, the gNB may transmit an RRC resume message (eg, RRCResume message) to the UE. Then, after the UE transitions from the RRC_INACTIVE state to the RRC_CONNECTED state, the UE may transmit an RRC resume complete message (eg, RRCResumeComplete message) to the gNB. For reference, if the grant for user data permits, the UE may also transmit user data in step 5).

6) When loss of DL user data buffered in the last serving gNB should be prevented, the gNB may transmit a forwarding address to the last serving gNB. For example, the gNB may transmit an address indication message (eg, an Xn-U ADDRESS INDICATION message) to the last serving gNB. For reference, step 6) is an additional step and may not be performed.

7 and 8) The gNB may perform a path switch. For example, the gNB may transmit a path switching request message (eg, a PATH SWITH REQUEST message) to the AMF. Then, the AMF may transmit a path switch request response message (eg, PATH SWITH REQUEST RESPONSE message) to the gNB.

9) The gNB may trigger the release of UE resources at the last serving gNB. For example, the gNB may transmit a UE context release message (eg, a UE CONTEXT RELEASE message) to the last serving gNB.

For reference, after step 1) is performed, when the gNB immediately rejects the UE's resumption request using a single RRC message, and maintains the UE in the RRC_INACTIVE state without reconfiguration, or the gNB establishes a new RRC connection. If you decide to set up, SRB0 (without security) may be used. Conversely, when the gNB decides to reset the UE (e.g., when resetting the UE with a new DRX (Discontinuous Reception) cycle or RNA (RAN Based Notification Area)) or when the gNB decides to push the UE to the RRC_IDLE state, SRB1 (the integrity protection and encryption applied previously set for this SRB) can be used.

For reference, SRB1 can be used only when a UE context is found after step 3).

Hereinafter, the RRC_INACTIVE state will be described in more detail.

<RRC Inactive status and CM- CONNCETED State (CM-CONNECTED with RRC Inactive state)>

RRC Inactive state can be applied to NG-RAN.

The NG-RAN may determine whether the RRC state of the UE can be switched to the RRC Inactive state. The AMF may provide support information to the NG-RAN to support the determination of the NG-RAN. The following examples are exceptional cases where the AMF does not provide support information:

-If the PLMN (or AMF set) does not support RRC Inactive;

-When the UE needs to maintain the CM-CONNECTED state (eg, for tracking)

"RRC Inactive Support Information" may include:

-UE specific DRX value;

-UE specific extended idle mode DRX values (cycle length and paging time window length);

-A registration area provided to the UE;

-Periodic registration update timer;

-When the AMF activates the Mobile Initiated Connection Only (MICO) mode for the UE, an indication (or information) that the UE is in the MICO mode;

-Information of the UE identifier allowing the RAN to calculate the RAN paging occasion of the UE.

To support the determination of the NG-RAN (determining whether the RRC state of the UE can be switched to the RRC Inactive state), the RRC Inactive support information is performed while N2 activation with the (new) serving NG-RAN node is performed, It can be provided by AMF (e.g., while a registration procedure, service request procedure, or handover procedure is being performed).

When the AMF allocates a new registration area to the UE, the AMF may update the new registration area by transmitting RRC Inactive support information to the NG-RAN.

The RRC Inactive state is part of the RRC state, and the RAN may determine a condition for the UE to enter the RRC Inactive state. When the parameter included in the RRC Inactive support information is changed according to the result of the NAS procedure, the AMF may update the RRC Inactive support information to the NG-RAN node.

When the UE is in the CM-CONNECTED state, if the AMF provides RRC Inactive support information, the RAN may determine to change the RRC state and CM state of the UE to the CM-CONNECTED with RRC Inactive state.

The "endpoints" and states of the N2 and N3 reference points are not changed by the UE entering the CM-CONNECTED with RRC Inactive state. The UE in the RRC Inactive state knows the RAN notification area and the periodic RAN notification area update timer.

The 5GC network may not recognize the state transition of the UE between the CM-CONNECTED with RRC Connected state and the CM-CONNECTED with RRC Inactive state state unless notified by the N2 notification procedure.

When the UE switches to the CM-CONNECTED with RRC Inactive state, the NG-RAN may set a periodic RAN notification area update timer to the UE in consideration of the periodic RAN notification area update timer value indicated in the RRC Inactive support information. In addition, the NG-RAN may use a guard timer having a longer value than the RAN notification area update timer value provided to the UE.

When the periodic RAN notification area update guard timer expires in the NG-RAN, the NG-RAN may initiate an AN release procedure.

When the UE is in the CM-CONNECTED with RRC Inactive state state, the UE may resume RRC connection for the following reasons:

-When uplink data is pending;

-Mobile initiated NAS signaling procedure;

-Response to RAN paging;

-When notifying the network that the UE has left the RAN notification area;

-When the periodic RAN notification area update timer has expired.

When the UE resumes connection with a different NG-RAN in the same PLMN or in an equivalent PLMN, the NG-RAN may retrieve the UE AS context from an existing NG-RAN node (old NG-RAN node).

When the RAN paging procedure has not successfully established connection with the UE, the paging procedure may be processed by the network as follows:

-When the NG-RAN has at least one NAS PDU session pending for transmission, the CM state of the UE in the AMF is switched to CM-IDLE, and NAS non-delivery to the AMF In order to notify, the RAN node may initiate an AN release procedure.

-If the NG-RAN has only user plane data for pending transmission, the NG-RAN node may maintain the N2 connection in an active state or initiate an AN release procedure based on the local setting of the NG-RAN. .

For reference, when RAN paging fails, user plane data triggering RAN paging may be lost.

Additionally, in the following cases, the UE in the CM-CONNECTED state with RRC Inactive state enters the CM-IDLE state and may initiate a NAS signaling recovery procedure:

-If the RRC resume procedure has failed;

-When the UE receives the core network paging;

-Periodically, when the RAN notification area update timer expires, and the UE cannot successfully resume the RRC connection;

-A failure scenario that cannot be resolved in the RRC Inactive state, and the UE must switch to the CM-IDLE state.

When the UE is in the CM-CONNECTED with RRC Inactive state, and a trigger for changing the UE's NG-RAN UE radio capability information occurs, the UE moves to the CM-IDLE state and transmits the UE radio capability information. The procedure for updating can be initiated.

When the UE is in the CM-CONNECTED with RRC Inactive state and the RAN receives a Location Reporting Control message (including a reporting type indicating single stand-alone reporting) from the AMF, the RAN is Before reporting the location to the AMF, a RAN paging procedure may be performed.

When the UE is in the CM-CONNECTED with RRC Inactive state and the RAN receives a location reporting control message (including a reporting type indicating that the UE continuously reports every time the cell changes) from the AMF, the RAN A Location Report message (including the last known location of the UE with a time stamp) can be transmitted to the AMF.

When the UE is in the CM-CONNECTED with RRC Inactive state, and the AMF receives a deregistration notification message (eg, Nudm_UEContextManagement_DeregistrationNotification message) from the UDM, the AMF may initiate the AN release procedure.

When the UE is in the CM-CONNECTED with RRC Inactive state and the RAN receives a location reporting control message (including a Reporting Type of the Area Of Interest based reporting) from the AMF, The RAN may transmit a Location Report message (including information on the existence of the UE in the region of interest (eg, IN, OUT or UNKNOWN) and the last known location of the UE together with a time stamp) to the AMF. .

When the UE is in the CM-CONNECTED with RRC Inactive state, and the existing NG-RAN node that has switched the UE to the RRC Inactive state receives downlink N2 signaling, the existing NG-RAN node can initiate the RAN paging procedure. have. When the UE resumes RRC connection to another NG-RAN node, the existing NG-RAN node includes a "UE Context Transfer" indication (or information) in the response container to generate downlink N2 signaling. Function) (for example, AMF or SMF). Then, when the path switching from the existing NG-RAN node to the new NG-RAN node is completed, a network function (NF) (eg, AMF or SMF) may retry the same procedure.

<D2D(Device to Device) communication>

On the other hand, in the following, D2D communication will be described.

11 shows an example of the concept of D2D (Device to Device) communication.

Due to the increase in user requirements for SNS (Social Network Service), communication between UEs at a physically close distance, that is, device to device (D2D) communication is required.

In order to reflect the above-described requirements, as shown in FIG. 11, between UE#1 (100-1), UE#2 (100-2), UE#3 (100-3), or between UE#4 (100- 4) A method of allowing direct communication between UE#5 (100-5) and UE#6 (100-6) without the intervention of the base station (gNB) 300 is being discussed. Of course, with the help of the base station (gNB) 300, it is possible to communicate directly between the UE#1 100-1 and the UE#4 100-4. Meanwhile, UE#4 (100-4) may serve as a repeater for UE#5 (100-5) and UE#6 (100-6). Similarly, UE#1 100-1 may serve as a repeater for UE#2 100-2 and UE#3 100-3 that are far from the cell center.

Meanwhile, D2D communication is also called proximity service (ProSe). In addition, a UE performing proximity service is also referred to as a ProSe UE. In addition, a link between UEs used for the D2D communication is also referred to as a sidelink.

Physical channels used for the sidelink include the following.

-PSSCH (Physical Sidelink Shared Channel)

-PSCCH (Physical Sidelink Control Channel)

-PSDCH (Physical Sidelink Discovery Channel)

-PSBCH (Physical Sidelink Broadcast Channel)

In addition, physical signals used in the side link include the following.

-Demodulation Reference signal (DMRS)

-Sidelink Synchronization signal (SLSS)

The SLSS includes a primary sidelink synchronization signal (PSLSS) and a secondary sidelink synchronization signal (Secondary SLSS: SSLSS).

Degree 12 is UE -To-network relay ( UE -to-Network Relay) architecture. 13 is UE -To-network relay ( UE -to-Network Relay) shows an example of the protocol stack of the control plane. Degree 14 is UE -To-network relay ( UE -to-Network Relay) shows an example of the protocol stack of the user plane.

Referring to FIG. 12, a UE-to-Network Relay supports network connection of a remote UE.

The PC5 link is the interface between the UE and the UE-to-network relay. The Uu link is the interface between the UE-to-network relay and the base station.

If the UE has established a PC5 link with a UE-to-network relay, the UE is considered a remote UE.

A 5G ProSe UE-to-Network Relay entity (refer to 5G ProSe UE-to-Network Relay in FIG. 12) may provide a function of supporting connectivity to a network for Remote UEs. The UE-to-Network Relay can be used for both public safety services and commercial services (eg, interactive services).

When a UE (e.g., a remote UE) successfully establishes a PC5 link to a 5G ProSe UE-to-Network Relay, the UE (e.g., a remote UE) will be considered a Remote UE for a specific 5G ProSe UE-to-Network Relay. I can. The remote UE may be located within NG-RAN coverage or outside NG-RAN coverage.

The 5G ProSe UE-to-Network Relay may relay unicast traffic (UL and DL traffic) between a remote UE and a network. The 5G ProSe UE-to-Network Relay should provide a general function to relay all IP traffic.

For unicast traffic between Remote UEs and 5G ProSe UE-to-Network Relays, One-to-one Direct Communication may be used.

The protocol stack of FIGS. 13 and 14 may be a protocol stack for a Layer-2 UE-to-Network Relay. Examples of the protocol stack for Layer-2 UE-to-Network Relay in FIGS. 13 and 14 show a protocol stack in EPS, but this is only an example, and a protocol stack may be used for 5GS as well. For example, the eNodeB protocol stack may be used by the gNB, the MME protocol stack may be used by the AMF, and the SGW/PGW protocol stack may be used by the UPF. In addition, in FIGS. 13 and 14, the Uu interface may be used as the LTE-Uu interface between the UE and the base station, and the interface between the base station and the network core entity and the interface between the network core entities are replaced by interfaces defined in 5GS. Can be interpreted.

Communication between the remote UE and the UE-to-Network Relay is performed by one-to-one direct communication.

II. Problems to be solved by the disclosure of the present specification

In EPS, a study on Layer-2 UE-to-Network Relay was conducted. An example of a control plane protocol stack and an example of a user plane protocol stack when a Layer-2 UE-to-Network Relay (eg, eRelay-UE) provides a network connection service to a Remote UE (eg, eRemote UE) is shown in FIG. And the same as in FIG. 14.

When the remote UE is connected to the network through Layer 2 Relay (i.e., Layer-2 UE-to-Network Relay), the remote UE transmits NAS messages and RRC messages to the network through the Layer 2 Relay UE, and It is possible to receive a NAS message and an RRC message through the 2 Relay UE. When the remote UE is connected to the network through Layer 2 Relay (ie, Layer-2 UE-to-Network Relay), the network must perform mobility management for the Remote UE.

On the other hand, when the remote UE is connected to the network through Layer 3 Relay (i.e., Layer-3 UE-to-Network Relay), the remote UE transmits NAS messages and RRC messages to the network through the Layer 3 Relay UE, or NAS messages and RRC messages cannot be received from the Layer 3 Relay UE. That is, when the remote UE is connected to the network through Layer 3 Relay (ie, Layer-3 UE-to-Network Relay), the remote UE cannot transmit or receive NAS messages and RRC messages to the network by itself. When the remote UE is connected to the network through Layer 3 Relay (ie, Layer-3 UE-to-Network Relay), the Remote UE can only receive traffic for the Remote UE by Layer 3 Relay and/or the network.

In EPS, Layer 3 Relay (ie, Layer-3 UE-to-Network Relay) was introduced, and Layer 2 Relay (ie, Layer-2 UE-to-Network Relay) was not introduced. In 5GS, a method of introducing Layer 2 Relay (ie, Layer-2 UE-to-Network Relay) is being discussed.

For reference, in the disclosure of the present specification, the Relay UE may mean a Layer-2 Relay UE. Relay UE, Layer-2 UE-to-Network Relay, eRelay-UE (evolved Relay UE), and evolved ProSe UE-to-Network Relay UE may all have the same meaning. In the disclosure of this specification, the remote UE may mean a Layer-2 remote UE. Remote UE, Layer-2 UE-to-Network Relay, eRemote-UE (evolved Remote UE), and evolved ProSe Remote UE may all be used interchangeably.

When describing the remote UE, the RRC_CONNECTED state may mean that the UE has a context in the eNB or the gNB.

While the remote UE is connected to the relay UE, it does not need to be in the RRC_CONNECTED state. The relay UE may be in the RRC_IDLE state while connected to the remote UE. Independently from the connection state of the PC5 connection or non-3GPP access between the remote UE and the relay UE, the RRC connection state (ie, RRC state) of the remote UE and the RRC state of the relay UE may be changed.

While the Relay UE is connected to the Remote UE and unicast data is relayed, both the Remote UE and the Relay UE are in RRC_CONNECTED state. Other than that, the RRC states of the relay UE and the remote UE may be independent.

For example, when the remote UE is RRC_IDLE, the relay UE may be RRC_CONNECTED. In this case, the remote UE may be in the RRC_IDLE state because communication with the network is not performed. On the other hand, the relay UE may be in the RRC_CONNECTED state because communication with the network is performed.

For another example, when the remote UE is in the RRC_INACTIVE state, the relay UE may be in the RRC_IDLE state. Or, when the remote UE is in the RRC_IDLE state, the relay UE may be in the RRC_INACTIVE state.

In EPS, only the RRC_IDLE and RRC_CONNECTED states are defined. However, since the RRC_INACTIVE state is newly defined in 5GS, RRC_INACTIVE needs to be considered.

When the remote UE and/or the relay UE are in the RRC_INACTIVE state, there may be a problem in that data on the remote UE is not effectively transmitted to the remote UE.

For example, when the remote UE is in the RRC_INACTIVE state and the relay UE is in the RRC_IDLE state, assume a situation in which a mobile terminating (MT) service (eg, MT data or MT signaling) to the remote UE occurs. The NG-RAN (eg, last serving NG-RAN) that served the remote UE when the remote UE in the current RRC_INACTIVE state was previously changed from the RRC_CONNECTED state to the RRC_INACTIVE state has a context for the remote UE. That is, there may be an NG-RAN that stores and manages the context of the Remote UE in the RRC_INACTIVE state. Accordingly, data related to the generated MT service may be transmitted to the last serving NG-RAN (ie, the NG-RAN that stores and manages the context of the Remote UE in the RRC_INACTIVE state). Meanwhile, since the Relay UE is currently in the RRC_IDLE state, there may not be any NG-RAN that stores and manages the context for the Relay UE. In order for data related to the generated MT service to be transmitted to the remote UE, data related to the generated MT service must be transmitted to the remote UE through the relay UE. However, since there is no NG-RAN that stores and manages the context for the relay UE, there may be a problem that data related to the generated MT service cannot be transmitted to the remote UE.

In the above example, an example was taken when the Remote UE is in RRC_INACTIVE state and the Relay UE is in RRC_IDLE state, but even when both the Remote UE and Relay UE are in RRC_INACTIVE state, and when the Remote UE is RRC_IDLE and Relay UE is in RRC_INACTIVE state, Data (data related to the MT service to the remote UE) may not be effectively transmitted to the remote UE.

Therefore, when the remote UE and/or the relay UE is in RRC_INACTIVE state (e.g., when the remote UE is in RRC_INACTIVE state and the relay UE is in RRC_IDLE state, when both the remote UE and relay UE are in RRC_INACTIVE state, and the remote UE is RRC_IDLE and relay In case the UE is in the RRC_INACTIVE state), a method of supporting MT service for the remote UE should be considered. That is, in order to solve the above problems, there is a need for a method in which a relay UE and/or a network supports an incoming service (MT service) to a remote UE.

III. Disclosure of this specification

The disclosures described later in this specification may be implemented in one or more combinations. Each of the drawings shows an embodiment of each disclosure, but the embodiments of the drawings may be implemented in combination with each other.

A relay UE and/or a network-to-remote UE service (MT service) scheme proposed in the disclosure of the present specification may consist of a combination of one or more operations/configurations/steps described below.

For reference, in this specification, a user equipment (UE) and a terminal are mixed and described. In addition, UE-to-Network Relay, ProSe UE-to-Network Relay, Relay, Relay UE, UE-NW Relay, eRelay, eRelay UE, eRelay-UE, ProSe Relay, ProSe Relay UE are mixed to describe the Relay UE. do. In addition, a Remote UE, eRemote UE, eRemote-UE, ProSe Remote UE, and ProSe Remote are used in combination to describe a Remote UE.

The operations described in the disclosure of the present specification may be applied to various services (eg, V2X, public safety, IoT, etc.).

In the disclosure of the present specification, PC5 may mean NR PC5, LTE PC5, or both NR PC5 and LTE PC5. In the disclosure of this specification, NG-RAN may mean gNB or both gNB and ng-eNB.

Hereinafter, in the first to fourth examples of the disclosure of the present specification, since a remote UE (UE-2) requires a network connection service, UE-1 is selected as a UE-to-Network Relay and UE-1 (Relay UE). ), the network connection service request is performed. For this reason, it is assumed that a PC5 unicast link is formed (or created or established) between UE-1 and UE-2. In the disclosure of the present specification, the PC5 unicast link may be used interchangeably with a unicast link, an L2 link, and a Layer-2 link.

When UE-1 and UE-2 form a “relay UE and remote UE relationship” (or to establish a relationship), UE-1 and/or UE-2 may interact with the network (eg: Interaction for authentication/authorization can be performed). At this time (or later), each UE's serving AMF (e.g., UE-1's serving AMF and UE-2's serving AMF) acquires the counterpart UE's information (e.g., counterpart UE's ID, temporary ID, etc.) It may be stored in the context of the UE. For example, the serving AMF (AMF-2) of UE-2, which is a remote UE, is information of UE-1, which is a relay UE (e.g., SUPI (Subscription Permanent Identifier) of UE-1, Global Unique Temporary Identifier (5G-GUTI)) , 5G-S-TMSI (System Architecture Evolution (SAE)-Temporary Mobile Subscriber Identity), 5G-TMSI (Temporary Mobile Subscriber Identity), serving AMF information, etc.) may be stored in the context of UE-2.

1. First example of disclosure of this specification

In the first example of the disclosure of the present specification, when the relay UE is in the RRC_IDLE state and the remote UE is in the RRC_INACTIVE state, operations for supporting MT service to the remote UE are described. For example, in FIG. 15, an example in which the NG-RAN performs RAN paging is described, and in FIG. 16, an example in which the NG-RAN requests paging from the AMF is described.

The following drawings are prepared to explain a specific example of the present specification. Since the names of specific devices or names of specific signals/messages/fields described in the drawings are provided by way of example, technical features of the present specification are not limited to specific names used in the following drawings.

Degree 15 is It shows a signal flow diagram according to the first example of the first example of the disclosure of the present specification.

0) UE-1 (Relay UE) may be in RRC_IDLE state, and UE-2 (Remote UE) may be in RRC_INACTIVE state.

1) MT service to UE-2 may occur. Accordingly, the UPF can receive downlink data to UE-2 (downlink data related to MT service to UE-2).

2) Since UE-2 is in the RRC_INACTIVE state, downlink data received by the UPF may be transmitted to the last serving NG-RAN of UE-2. That is, the UPF may transmit downlink data to UE-2 to the NG-RAN.

3) The NG-RAN can check whether both UE-1 and UE-2 are in RRC_CONNECTED state. The NG-RAN may recognize that UE-1 is in an RRC_IDLE state and that UE-2 is in an RRC_INACTIVE state. In order to transmit downlink data to UE-2, the NG-RAN must make UE-2 in the RRC_INACTIVE state into the RRC_CONNECTED state. In order to switch UE-2 to the RRC_CONNECTED state, UE-1 must first switch from the RRC_IDLE state to the RRC_CONNECTED state. This is because UE-1 can make UE-2 into RRC_CONNECTED state only when UE-1 is in RRC_CONNECTED state, and can transmit downlink data to UE-2. To this end, the NG-RAN may perform a paging procedure for UE-1. For example, the NG-RAN may transmit a paging message to UE-1.

The paging message transmitted by the NG-RAN to UE-1 may include one or more of the following information a) to d).

a) ID information of UE-1 as a relay UE: For example, the ID information of UE-1 as a relay UE may be 5G-S-TMSI information of UE-1. However, this is only an example, and in the scope of the disclosure of the present specification, the ID information of UE-1 includes ID information of any UE-1 that allows UE-1 to recognize that it should receive a paging message. Can include. It is assumed that the NG-RAN stores ID information of UE-1, a relay UE of UE-2. For example, the NG-RAN may store information about the Relay UE (eg, ID information of UE-1) in the context of UE-2 that it stores.

b) ID information of UE-2, which is a remote UE: For example, ID information of UE-2, which is a remote UE, may be I-RNTI (Inactive Radio Network Temporary Identifier) information of UE-2. However, this is only an example, and in the scope of the disclosure of the present specification, the ID information of UE-2 allows the device (eg, UE-1) that receives the ID information of UE-2 to identify UE-2. It may include ID information of any UE-2.

c) Information instructing the Relay UE to perform paging to the Remote UE

d) Information indicating that MT data for the remote UE has occurred

In order for the paging message to include one or more of information from a) to d), an existing paging message may be extended and used. Alternatively, in order for the paging message to include one or more of information a) to d) above, an RRC message may be newly defined. When the RRC message is newly defined, a message indicating paging associated with the relay may be defined, for example, a "paging for relay message".

Table 3 below shows an example of a conventional paging message.

- ASN1START - TAG-PAGING-START Paging ::= SEQUENCE {pagingRecordList PagingRecordList OPTIONAL, - Need N lateNonCriticalExtension OCTET STRING OPTIONAL, nonCriticalExtension SEQUENCE{} OPTIONAL} PagingRecordList ::= SEQUENCE (SIZE(1..maxNrof) OF PagingRecord PagingRecord ::= SEQUENCE {ue-Identity PagingUE-Identity, accessType ENUMERATED {non3GPP} OPTIONAL, - Need N ...} PagingUE-Identity ::= CHOICE {ng-5G-S-TMSI NG-5G-S- TMSI, fullI-RNTI I-RNTI-Value, ...} - TAG-PAGING-STOP - ASN1STOP

The example paging message of Table 3 may be used to notify one or more UEs. The Radio Link Control (RLC)-Service Access Point (SAP) used for the paging message may be a Transparent Mode(TM). The logical channel used for the paging message may be a Paging Control Channel (PCCH). The direction in which the paging message is transmitted may be “Network to UE (UE)”.

The paging message may include a pagingRecordList field, a lateNonCriticalExtension field, and a nonCriticalExtension field. The pagingRecordList field may contain a maximum of maxNrofPageRec PagingRecords. The lateNonCriticalExtension field and the nonCriticalExtension field are marked with OCTET STRING and SEQUENCE{}, respectively, and may include parameters added when additional parameters are required in a paging message later.

PagingRecordList may include PagingRecord. PagingRecord may include ue-Identity and accessType.

accessType may indicate the access type of paging. For example, when accessType indicates "non3GPP", accessType may indicate that a paging message is generated due to a PDU session of non-3GPP access.

The ue-Identity may include ID information (PagingUE-Identity) of the UE to be paging. PagingUE-Identity may include ng-5G-S-TMSI and fullI-RNTI. ng-5G-S-TMSI may include NG-5G-S-TMSI. fullI-RNTI may include I-RNTI-Value.

In a manner that includes one or more information from a) to d) above, a paging message as shown in Table 3 may be extended and used.

For example, the ue-Identity of Table 3 may include a) ID information of UE-1, which is a relay UE, or b) ID information of UE-2, which is a remote UE. Alternatively, the paging message may include both a) ID information of UE-1 as a relay UE and b) ID information of UE-2 as a remote UE. a) ID information of UE-1, which is a relay UE, or b) ID information of UE-2, which is a remote UE, a) ID information of UE-1, which is a relay UE, or b) UE-2, which is a remote UE. One of the ID information may be included in ue-Identity, and the other may be included in a newly defined IE (eg, remoteUE-Identity or relayUE-Identity) by defining a new IE (Information Element).

For example, in order to include information instructing the Relay UE to perform paging to the Remote UE in the example paging message of Table 3, a new IE may be defined. As an example, an IE instructing the Relay UE to perform paging to the Remote UE may be newly defined, such as "paging to Remote UE". For another example, a value corresponding to the accessType in the example of Table 3 may be newly defined, and c) information instructing the Relay UE to perform paging to the Remote UE may be included in the accessType. For example, a value such as "over Relay" or "via Relay" may be newly defined, and c) information instructing the Relay UE to perform paging to the Remote UE may be included in the accessType.

For example, in order to include information indicating that MT data for the remote UE has occurred in the paging message of the example of Table 3 d), a new IE may be defined. For example, by defining a new IE such as "MTdataToRemoteUE" and including it in the PagingRecord field, information indicating that MT data for the remote UE has occurred may be included in the paging message.

The NG-RAN may perform paging based on the RNA (RAN-based Notification Area) of UE-2. Alternatively, the NG-RAN may perform paging based on the registration area (RA) of UE-2. For reference, the NG-RAN may receive RRC Inactive support information including information on the RA of UE-2 from the AMF. Alternatively, the NG-RAN may perform paging on the basis of the NG-RAN that served UE-1 before UE-1 enters the RRC_IDLE state or the cell camped before UE-1 enters the RRC_IDLE state. Here, it is assumed that the NG-RAN stores information on the NG-RAN that served UE-1 before UE-1 enters the RRC_IDLE state or information on the cell camped before UE-1 enters the RRC_IDLE state. .

The NG-RAN is based on the above-described methods (e.g., paging based on RNA of UE-2, paging based on RA of UE-2, paging based on NG-RAN that served UE-1 before UE-1 entered RRC_IDLE state). , Or paging based on the cell camped before UE-1 enters the RRC_IDLE state), or two or more schemes may be used in sequence. The NG-RAN is based on the above-described methods (e.g., paging based on RNA of UE-2, paging based on RA of UE-2, paging based on NG-RAN that served UE-1 before UE-1 entered RRC_IDLE state). , Or paging based on the cell camped before UE-1 entered the RRC_IDLE state), if two or more of the schemes are sequentially used, if UE-1 does not respond to paging in the scheme attempted first, the NG-RAN You can try paging using the following scheme. For example, the NG-RAN has the methods described above (e.g., paging based on RNA of UE-2, paging based on RA of UE-2, NG- which served UE-1 before UE-1 enters RRC_IDLE state). Paging based on RAN, or paging based on the cell camped before UE-1 entered the RRC_IDLE state, etc.), first try a method to attempt paging in a narrow range, and then try a method to attempt paging in a wide range. You can try.

4) When UE-1 receives the paging message, it may respond to the paging message. For example, UE-1 may perform an RRC connection procedure for switching from RRC_IDLE to RRC_CONNECTED (eg, see the example of FIG. 9) and a service request procedure (eg, see the examples of FIGS. 7A to 7C). For example, the UE transmits an RRC setup request message (eg, the RRCSetupRequest message of FIG. 9) to the NG-RAN to the NG-RAN to perform an RRC connection procedure (eg, see the example of FIG. 9) to switch from RRC_IDLE to RRC_CONNECTED. can do. For example, UE-1 may transmit a service message to AMF-1 (AMF of a Relay UE) to perform a service request procedure (eg, see the examples of FIGS. 7A to 7C).

The RRC setup request message (eg, the RRCSetupRequest message of FIG. 9) transmitted by UE-1 to create (or establish) an RRC connection with the network may include an establishment cause (eg, EstablishmentCause) value. One of the following i) to iii) can be set as the establishment cause (eg, EstablishmentCause) value:

i) mt-Access: The “mt-Access” value may be used by a conventional UE to respond to paging initiated from a core network (eg, AMF). When the UE transmits an RRC setup request message including an establishment cause (eg, EstablishmentCause) in which the “mt-Access” value is set to the NG-RAN, the NG-RAN may deliver it to the AMF. On the other hand, paging in the example of FIG. 15 does not start from AMF, but from NG-RAN. At this time, after UE-1 establishes (or creates) an RRC connection with the NG-RAN by transmitting an RRC setup request message including "mt-Access" to the NG-RAN, UE-1 sends a service request message to the AMF- Can be sent to 1. For reference, the AMF-1 may receive an establishment cause (eg, EstablishmentCause) value (ie, “mt-Access”) used by the UE from the NG-RAN. AMF-1 may reject processing of the service request message transmitted by UE-1 because there is no paging initiated by the AMF-1.

In order that AMF-1 does not reject the service request message, UE-1 relays the service request procedure initiated by the UE to an RRC message (eg, an RRC message including a service request message or another RRC message) and/or a service request message. Information indicating that it is for operation (or information indicating that it is for a network connection service or information indicating that it is for a remote UE) may be explicitly or implicitly included. In addition, UE-1 is an RRC message including information indicating that the service request procedure initiated by the UE is for a relay operation (or information indicating that it is for a network connection service or information indicating that it is for a service for a remote UE), and / Or can send a service request message. Then, on the basis of the information indicating that the AMF-1 is for the relay operation (or the information indicating that the network connection service or the information indicating that the service for the Remote UE), the service request message transmitted by the UE-1 You can decide to process.

In summary, when UE-1 transmits an RRC setup request message including "mt-Access" to the NG-RAN to establish (or generate) an RRC connection with the NG-RAN, UE-1 is initiated by UE-1 An RRC message and/or a service request message including information indicating that the service request procedure is for a relay operation (or information indicating that it is for a network connection service or information indicating that it is for a service to a remote UE) may be transmitted.

ii) EstablishmentCause value other than mt-Access among the existing EstablishmentCause values: For example, the EstablishmentCause value previously defined such as mo-Signalling and mo-Data is the EstablishmentCause value of the RRC setup request message transmitted by UE-1 Can be set to

iii) EstablishmentCause value newly defined for the disclosure of the present specification: For example, an EstablishmentCause value for the Relay operation of UE-1 may be newly defined, such as "relay". For example, "relay" may be set as an EstablishmentCause value of an RRC setup request message transmitted by UE-1.

As described above, UE-1 may transmit an RRC setup request message including an establishment cause (eg, EstablishmentCause) value set as one of i) to iii) to the NG-RAN.

UE-1 may explicitly or implicitly/implicitly provide information indicating that it operates as a UE-to-Network Relay to the network. For example, when UE-1 transmits an RRC message (eg, an RRC setup request message) to the NG-RAN and/or when transmitting a NAS message (eg, a service request message) to the AMF, the UE-to-Network Information indicating that it operates as a relay can be explicitly or implicitly/implicitly notified to the network. For example, UE-1 will explicitly include information indicating that it operates as a UE-to-Network Relay in an RRC message (eg, an RRC setup request message) and/or a NAS message (eg, a service request message). I can.

UE-1 may camp on an NG-RAN other than the last serving NG-RAN of UE-2. In this case, the NG-RAN camped by UE-1 (ie, serving NG-RAN of UE-1) may not have a UE-2 related context. The NG-RAN camped by UE-1 (ie, serving NG-RAN of UE-1) may perform an operation of fetching UE-2 related context from the last serving NG-RAN of UE-2.

For example, an operation in which the serving NG-RAN of UE-1 obtains a context related to UE-2 from the last serving NG-RAN of UE-2 is the serving NG-RAN of UE-1 and the last serving NG of UE-2. It may be performed between -RANs. For another example, the operation of obtaining a UE-2 related context from the last serving NG-RAN of UE-2 of UE-1 may be performed through AMF.

Serving NG-RAN of UE-1 The operation of obtaining a UE-2 related context from the last serving NG-RAN of UE-2 may be performed when UE-1 establishes (or establishes) an RRC connection, or step 7) It may be performed due to the operation of (eg, the UE context search process of step 2) and step 2) of the example of FIG. 10 may be performed).

When the serving NG-RAN of UE-1 gets the UE-2 related context from the last serving NG-RAN of UE-2, the serving NG-RAN of UE-1 is maintained by the last serving NG-RAN of UE-2. Downlink data to UE-2 may also be imported. Alternatively, when the serving NG-RAN of UE-1 performs step 12), after obtaining downlink data from the last serving NG-RAN of UE-2 to UE-2, it is transmitted to UE-2 via UE-1. May be.

5) UE-1 may be in the RRC_CONNECTED state. As UE-1 enters the RRC_CONNECTED state, it may enter the CM_CONNECTED state.

6) UE-1 may page UE-2. For example, UE-1 may transmit a paging message to UE-2. The paging message transmitted by UE-1 may be a PC5 message (eg, a PC5-S message, a PC5 paging message, a PC5-RRC message, etc.). PC5-S may mean control plane signaling performed through the PC5 interface. That is, UE-1 may transmit a paging message to UE-2 using the PC5 link between UE-1 and UE-2.

The paging message transmitted by UE-1 may include one or more of the following information:

a) ID information of UE-2, which is a remote UE: The ID information of UE-2 may be I-RNTI (Inactive Radio Network Temporary Identifier) information of UE-2. However, this is only an example, and in the disclosure of the present specification, the ID information of UE-2 may be ID information of any UE-2 capable of identifying UE-2.

b) Information indicating that MT data to the remote UE has occurred.

UE-1 may configure a paging message for paging UE-2 based on the paging message received from the NG-RAN in step 3).

For reference, in the example of FIG. 15, step 6) is illustrated as performing step 5), but this is only an example, and step 6) may be performed immediately after step 3).

7) UE-2 may perform an operation (eg, operations according to the example of FIG. 10) for switching from the RRC_INACTIVE state to the RRC_CONNECTED state. For example, UE-2 may transmit an RRC resume request message (eg, an RRCResumeRequest message) to the NG-RAN through UE-1. Since the RRC resume request message (e.g., RRCResumeRequest message) is transmitted to UE-1 through the PC5 interface between UE-2 and UE-1, the RRC resume request message (e.g., RRCResumeRequest message) is a PC5 message (e.g., PC5-S). Message, PC5 paging message, PC5-RRC message, etc.) and transmitted to UE-1.

UE-1 may transmit the RRC resume request message (eg, RRCResumeRequest message) received from UE-2 to the NG-RAN as it is. Alternatively, UE-1 may transmit an RRC resumption request message (eg, RRCResumeRequest message) received from UE-2 and information generated by UE-1 to the NG-RAN together. For example, the information generated by UE-1 may include information indicating that UE-1 operates as a relay and/or ID information of UE-1.

Regarding the operation of the remote UE to transmit a message to the network through the relay UE, for the message transmission between the remote UE and the relay UE and the message transmission between the relay and the network, UE-1 and UE in step 7) The operation performed by -2 may be equally applied throughout the disclosure of this specification.

8) The NG-RAN may perform radio resource configuration (eg, RRC reconfiguration operation) for data transmission and reception with UE-2 with UE-1. The radio resource configuration performed by the NG-RAN with UE-1 may include an operation of performing configuration related to a data radio bearer required by UE-2 with UE-1. To this end, the NG-RAN may use an RRC reconfiguration message (for example, an RRCReconfiguration message), or may use another RRC message (an existing RRC message related to radio resource configuration or a newly defined RRC message). The RRC reconfiguration message (eg, RRCReconfiguration message) can be extended and used. For example, by defining a new field corresponding to or similar to the radioBearerConfig field, configuration information related to a data radio bearer required by UE-2 may be included. At this time, information indicating that this configuration information is for UE-2 may be included together. Another example is to expand fields included in the existing radioBearerConfig field, and the drb-ToAddModList field can include information indicating that it is for UE-2 and configuration information related to the data radio bearer required by UE-2. have.

9) The NG-RAN may transmit an RRC resume message (eg, RRCResume message) to UE-2. For example, the NG-RAN may transmit an RRC resume message (eg, RRCResume message) to UE-2 through UE-1. The RRC resume message (e.g., RRCResume message) is transmitted to UE-2 through the PC5 interface in the section between UE-1 and UE-2, and the RRC resume message (e.g., RRCResume message) is a PC5 message (e.g., PC5- S message, PC5 paging message, PC5-RRC message, etc.) can be included and transmitted.

UE-1 may transmit the RRC resume message (eg, RRCResume message) received from the NG-RAN to UE-2 as it is. Alternatively, UE-1 may transmit an RRC resume message (eg, RRCResume message) received from the NG-RAN and information generated by UE-1 to UE-2 together. For example, the information generated by UE-1 may include information indicating that UE-1 operates as a relay and/or ID information of UE-1.

Regarding the operation of the remote UE to transmit a message to the network through the relay UE, for the message transmission between the remote UE and the relay UE and the message transmission between the relay and the network, UE-1 and UE in step 8) The operation performed by -2 may be equally applied throughout the disclosure of this specification.

For reference, step 8) may be performed after step 9) is performed, and steps 8) and 9) may be performed together.

10) UE-2 receiving the RRC resume message (eg, RRCResume message) may enter the RRC_CONNECTED state.

11) UE-2 may transmit an RRC resume complete message (eg, RRCResumeComplete message) to the NG-RAN through UE-1.

12) The NG-RAN may transmit downlink data to UE-2 through UE-1. Here, the downlink data may be transmitted to UE-1 through a radio resource established (or generated) by the NG-RAN with UE-1 in step 8). UE-1 may transmit downlink data to UE-2 through the PC5 user plane.

The following drawings are prepared to explain a specific example of the present specification. Since the names of specific devices or names of specific signals/messages/fields described in the drawings are provided by way of example, technical features of the present specification are not limited to specific names used in the following drawings.

16 shows a signal flow diagram according to a second example of the first example of the disclosure of the present specification.

A second example of the first example of the disclosure described in FIG. 16 describes a method of requesting AMF-2 to perform paging when the NG-RAN receives downlink data from the UPF to UE-2 do.

0) UE-1 (Relay UE) may be in RRC_IDLE state, and UE-2 (Remote UE) may be in RRC_INACTIVE state.

1) MT service to UE-2 may occur. Accordingly, the UPF can receive downlink data to UE-2 (downlink data related to MT service to UE-2).

2) Since UE-2 is in the RRC_INACTIVE state, downlink data received by the UPF may be transmitted to the last serving NG-RAN of UE-2. That is, the UPF may transmit downlink data to UE-2 to the NG-RAN.

3) The NG-RAN can check whether both UE-1 and UE-2 are in RRC_CONNECTED state. The NG-RAN may recognize that UE-1 is in an RRC_IDLE state and that UE-2 is in an RRC_INACTIVE state. The NG-RAN may transmit an N2 message (eg, N2 message triggering CN paging) requesting paging to the serving AMF of UE-2 (ie, AMF-2). The NG-RAN may perform step 3) after recognizing that UE-2 is receiving a network connection service through Realy (UE-1). Alternatively, based on the contents described in the first example of the first disclosure (see FIG. 15) of the present specification, the NG-RAN performed paging to find UE-1, which is a relay UE of UE-2 (eg, FIG. 15 In step 3) of the paging), the NG-RAN may perform step 3) in the case of failure (ie, it does not receive a response to paging from UE-1).

The N2 message transmitted from the NG-RAN to the AMF-2 may be a message used by extending the existing N2 message, or may be a newly defined N2 message for the disclosure of the present specification. The N2 message transmitted by the NG-RAN to AMF-2 may include one or more of the following information:

a) Information that can identify UE-2, which is a remote UE: The information that can identify UE-2, which is a remote UE, allows the AMF to recognize that the N2 message transmitted by the NG-RAN is for UE-2. It may be information that you do. For example, the information capable of identifying UE-2, which is a remote UE, may be an AMF UE NG Application Protocol (NGAP) ID of UE-2 and/or a RAN UE NGAP ID of UE-2. Alternatively, the information capable of identifying UE-2, which is a remote UE, may be ID information of UE-2, for example, ID information such as 5G-GUTI, 5G-S-TMSI, and 5G-TMSI of UE-2. I can.

b) ID information of UE-1 as a relay UE: ID information of UE-1 as a relay UE may be information capable of identifying UE-1. For example, it may be ID information such as 5G-GUTI, 5G-S-TMSI, and 5G-TMSI of UE-1.

c) Information requesting to perform paging for the Relay UE and/or UE-2

d) Information indicating that MT data to UE-2 has occurred

The NG-RAN may transmit an N2 message including one or more of a) to d) to AMF-2 and request paging from AMF-2.

Although not shown in FIG. 16, the AMF-2 receiving the N2 message from the NG-RAN may transmit a response message to the N2 message to the NG-RAN.

4) AMF-2 may perform an operation of paging UE-1 and UE-2. For example, AMF-2 may transmit a paging message to the NG-RAN.

The paging message transmitted by AMF-2 may include information that enables NG-RAN to page UE-1 and information that enables UE-1 to page UE-2. For example, the paging message is ID information of UE-1 (eg, may be 5G-S-TMSI of UE-1, but is not limited thereto and may be various types of ID information of UE-1) and The ID information of UE-2 (eg, may be 5G-S-TMSI of UE-2, but is not limited thereto, and may include various types of ID information of UE-1). The ID information of UE-1 and/or the ID information of UE-2 may be used by NG-RAN to paging UE-1, and the ID information of UE-2 may be used by UE-1 to paging UE-2. . Here, the paging message transmitted by the AMF-2 may be a paging message used by extending an existing paging message or a paging message newly defined for the disclosure of the present specification.

5) The NG-RAN can perform paging. For example, the NG-RAN may transmit a paging message to UE-1. Paging performed by the NG-RAN in step 5) may be performed in the same manner as paging performed by the NG-RAN in step 3) of FIG. 15.

6) UE-1 may receive a paging message from the NG-RAN and respond to the paging message. For example, UE-1 may perform an RRC connection procedure for switching from RRC_IDLE to RRC_CONNECTED (eg, see the example of FIG. 9) and a service request procedure (eg, see the examples of FIGS. 7A to 7C). The operation performed by UE-1 in step 6) may be performed in the same manner as the operation described in step 4) of FIG. 15.

UE-1 may camp on an NG-RAN other than the last serving NG-RAN of UE-2. In this case, the NG-RAN camped by UE-1 (ie, serving NG-RAN of UE-1) may not have a UE-2 related context. The NG-RAN camped by UE-1 (ie, serving NG-RAN of UE-1) may perform an operation of fetching UE-2 related context from the last serving NG-RAN of UE-2.

For example, an operation in which the serving NG-RAN of UE-1 obtains a context related to UE-2 from the last serving NG-RAN of UE-2 is the serving NG-RAN of UE-1 and the last serving NG of UE-2. It may be performed between -RANs. For another example, the operation of obtaining a UE-2 related context from the last serving NG-RAN of UE-2 of UE-1 may be performed through AMF.

The operation for the serving NG-RAN of UE-1 to obtain a UE-2 related context from the last serving NG-RAN of UE-2 may be performed when UE-1 establishes (or establishes) an RRC connection, or step 9 ) May be performed (eg, the UE context search process of step 2) and step 2) of the example of FIG. 10 may be performed).

When the serving NG-RAN of UE-1 gets the UE-2 related context from the last serving NG-RAN of UE-2, the serving NG-RAN of UE-1 is maintained by the last serving NG-RAN of UE-2. Downlink data to UE-2 may also be imported. Alternatively, when the serving NG-RAN of UE-1 performs step 13), after obtaining downlink data from the last serving NG-RAN of UE-2 to UE-2, it is transmitted to UE-2 through UE-1. May be.

7) UE-1 may enter the RRC_CONNECTED state. As UE-1 enters the RRC_CONNECTED state, it may enter the CM_CONNECTED state.

8 to 14) Steps 8) to 14) of FIG. 16 may be performed in the same manner as steps 6) to 12) of FIG. 15.

2. Second example of disclosure of this specification

In the second example of the disclosure of the present specification, when the relay UE is in the RRC_INACTIVE state and the remote UE is in the RRC_IDLE state, operations for supporting MT service to the remote UE are described.

The following drawings are prepared to explain a specific example of the present specification. Since the names of specific devices or names of specific signals/messages/fields described in the drawings are provided by way of example, technical features of the present specification are not limited to specific names used in the following drawings.

17 shows a signal flow diagram according to a second example of the disclosure of the present specification.

0) UE-1 (Relay UE) may be in RRC_INACTIVE state, and UE-2 (Remote UE) may be in RRC_IDLE state.

1) MT service to UE-2 may occur. Accordingly, the UPF can receive downlink data to UE-2 (downlink data related to MT service to UE-2).

2 and 3) Since UE-2 is in the RRC_IDLE state, a network triggered service request procedure (refer to the network initiated service request procedure of FIG. 8) may be performed. For example, steps 2a) to 3b) may be performed in the procedure described in the example of FIG. 8. As an example, the UPF may transmit a data notification message to the SMF. The SMF may transmit a message (eg, Namf_Communication_N1N2MessageTransfer message) to the AMF to inform the AMF that downlink data to UE-2 has occurred. The network initiation service request procedure performed in steps 2 and 3) may be performed as described in the example of FIG. 8.

4) AMF-2 may perform an operation of paging UE-1 and UE-2. For example, AMF-2 may transmit a paging message to the NG-RAN.

The paging message transmitted by AMF-2 may include information that enables NG-RAN to page UE-1 and information that enables UE-1 to page UE-2. For example, the paging message is ID information of UE-1 (eg, may be 5G-S-TMSI of UE-1, but is not limited thereto and may be various types of ID information of UE-1) and The ID information of UE-2 (eg, may be 5G-S-TMSI of UE-2, but is not limited thereto, and may include various types of ID information of UE-1). The ID information of UE-1 and/or the ID information of UE-2 may be used by NG-RAN to paging UE-1, and the ID information of UE-2 may be used by UE-1 to paging UE-2. . Here, the paging message transmitted by the AMF-2 may be a paging message used by extending an existing paging message or a paging message newly defined for the disclosure of the present specification.

5) The NG-RAN can check whether both UE-1 and UE-2 are in RRC_CONNECTED state. The NG-RAN may recognize that UE-1 is in an RRC_INACTIVE state and that UE-2 is in an RRC_IDLE state. The NG-RAN can perform paging. For example, the NG-RAN may transmit a paging message to UE-1. Paging performed by the NG-RAN in step 5) may be performed in the same manner as paging performed by the NG-RAN in step 3) of FIG. 15.

However, if the paging message transmitted by the NG-RAN to UE-1 includes “a) ID information of UE-1, which is a relay UE,” described in step 3) of FIG. 15, a) of UE-1, which is a relay UE I-RNTI information of UE-1 may be used for the ID information. And, when the paging message transmitted from the NG-RAN to UE-1 includes "b) ID information of UE-2, which is a remote UE," described in step 3) of FIG. 15, b) of UE-2, which is a remote UE 5G-S-TMSI information of UE-2 may be used for the ID information. Because, for a UE in the RRC_IDLE state (e.g., the Relay UE of FIG. 15 or the Remote UE of FIG. 17), the AMF triggers and the NG-RAN performs paging, at this time, the ID assigned by the AMF to the UE (i.e., 5G -S-TMSI). On the other hand, for a UE in the RRC_INACTIVE state (e.g., the Relay UE of Fig. 17, the Remote UE of Fig. 15), when the NG-RAN performs paging, the ID assigned by the NG-RAN to the UE (ie, I-RNTI) Because it uses.

For reference, the ID information of UE-1 (e.g., 5G-S-TMSI of UE-1) included in the paging message transmitted by AMF-2 to NG-RAN in step 4) is the I-RNTI of UE-1. Other ID information is included. The NG-RAN (e.g., the last serving NG-RAN of UE-1) can replace the ID information of UE-1 received from AMF-2 with I-RNTI based on the context of UE-1 that it stores. have. In addition, the NG-RAN may transmit a paging message including the I-RNTI of UE-1 to UE-1. In the operation of replacing the ID information of UE-1 received from AMF-2 by the NG-RAN with I-RNTI, the paging message (eg, CN paging message) received by the NG-RAN from AMF-2 is converted into a RAN paging message. It can be interpreted as converting and performing paging for UE-1.

6) UE-1 may perform an operation (eg, operations according to the example of FIG. 10) for switching from the RRC_INACTIVE state to the RRC_CONNECTED state. For example, UE-1 may transmit an RRC resume request message (eg, RRCResumeRequest message) to the NG-RAN. For a detailed example of performing an operation for the UE-1 to switch from the RRC_INACTIVE state to the RRC_CONNECTED state, refer to the example of FIG. 10.

7) The NG-RAN may transmit an RRC resume message (eg, RRCResume message) to UE-1.

8) UE-1 may be in the RRC_CONNECTED state.

9) UE-1 may transmit an RRC resume complete message (eg, RRCResumeComplete message) to the NG-RAN.

10) UE-1 may page UE-2. For example, UE-1 may transmit a paging message to UE-2. The paging message transmitted by UE-1 may be a PC5 message (eg, a PC5-S message, a PC5 paging message, a PC5-RRC message, etc.). That is, UE-1 may transmit a paging message to UE-2 using the PC5 link between UE-1 and UE-2.

The paging message transmitted by UE-1 may include one or more of the following information:

a) ID information of UE-2, which is a remote UE: ID information of UE-2 may be 5G-S-TMSI information of UE-2. However, this is only an example, and in the disclosure of the present specification, the ID information of UE-2 may be ID information of any UE-2 capable of identifying UE-2.

b) Information indicating that MT data to the remote UE has occurred.

UE-1 may configure a paging message for paging UE-2 based on the paging message received from the NG-RAN in step 5).

For reference, in the example of FIG. 17, step 10) is illustrated as performing step 9), but this is only an example, and step 10) may be performed immediately after step 5).

11) UE-2 may perform a procedure for switching from RRC_IDLE to RRC_CONNECTED (eg, see the example of FIG. 9) and a service request procedure (eg, see the example of FIGS. 7A to 7C). UE-2 may transmit a service request message to AMF-2 via UE-1. Although not shown in FIG. 17, the UE initiated service request procedure described in the examples of FIGS. 7A to 7C may be performed.

In this process, the NG-RAN may perform radio resource configuration (eg, RRC reconfiguration operation) for data transmission/reception with UE-2 with UE-1. The radio resource configuration performed by the NG-RAN with UE-1 may include an operation of performing configuration related to a data radio bearer required by UE-2 with UE-1. For example, the operations described in step 8) of FIG. 15 may be performed.

12) UE-2 may enter the RRC_CONNECTED state. As UE-2 enters the RRC_CONNECTED state, it may enter the CM_CONNECTED state.

13) UPF can transmit downlink data to UE-2. For example, when downlink data can be transmitted by the service request procedure performed in step 11), the UPF may perform step 13). The downlink data may be transmitted from the NG-RAN to the UE-1 through a radio resource formed by the NG-RAN with UE-1 in step 11). UE-1 may transmit downlink data to UE-2 through the PC5 user plane.

3. Third example of disclosure of this specification

In a third example of the disclosure of the present specification, when both the relay UE and the remote UE are in the RRC_INACTIVE state, operations for supporting the MT service to the remote UE are described.

The following drawings are prepared to explain a specific example of the present specification. Since the names of specific devices or names of specific signals/messages/fields described in the drawings are provided by way of example, technical features of the present specification are not limited to specific names used in the following drawings.

18 shows a signal flow diagram according to a third example of the disclosure of the present specification.

0) Both UE-1 (Relay UE) and UE-2 (Remote UE) may be in an RRC_INACTIVE state.

1) MT service to UE-2 may occur. Accordingly, the UPF can receive downlink data to UE-2 (downlink data related to MT service to UE-2).

2) Since UE-2 is in the RRC_INACTIVE state, downlink data received by the UPF may be transmitted to the last serving NG-RAN of UE-2. That is, the UPF may transmit downlink data to UE-2 to the NG-RAN.

3) The NG-RAN can check whether both UE-1 and UE-2 are in RRC_CONNECTED state. The NG-RAN may recognize that UE-1 is in the RRC_INACTIVE state and that UE-2 is in the RRC_INACTIVE state. In order to transmit downlink data to UE-2, the NG-RAN must make UE-2 in the RRC_INACTIVE state into the RRC_CONNECTED state. In order to switch UE-2 to the RRC_CONNECTED state, the NG-RAN must first switch UE-1 from the RRC_INACTIVE state to the RRC_CONNECTED state. This is because UE-1 can make UE-2 into RRC_CONNECTED state only when UE-1 is in RRC_CONNECTED state, and can transmit downlink data to UE-2. To this end, the NG-RAN may perform a paging procedure for UE-1. For example, the NG-RAN may transmit a paging message to UE-1.

The paging message transmitted by the NG-RAN to UE-1 may include one or more of the following information a) to d).

a) ID information of UE-1 as a relay UE: For example, ID information of UE-1 as a relay UE may be I-RNTI information of UE-1. However, this is only an example, and in the scope of the disclosure of the present specification, the ID information of UE-1 includes ID information of any UE-1 that allows UE-1 to recognize that it should receive a paging message. Can include. It is assumed that the NG-RAN stores ID information of UE-1, a relay UE of UE-2. For example, the NG-RAN may store information about the Relay UE (eg, ID information of UE-1) in the context of UE-2 that it stores.

b) ID information of UE-2 as a remote UE: For example, ID information of UE-2 as a remote UE may be I-RNTI information of UE-2. However, this is only an example, and in the scope of the disclosure of the present specification, the ID information of UE-2 allows the device (eg, UE-1) that receives the ID information of UE-2 to identify UE-2. It may include ID information of any UE-2.

c) Information instructing the Relay UE to perform paging to the Remote UE

d) Information indicating that MT data for the remote UE has occurred

In order for the paging message to include one or more of information from a) to d), an existing paging message may be extended and used. Alternatively, in order for the paging message to include one or more of information a) to d) above, an RRC message may be newly defined. When the RRC message is newly defined, a message indicating paging associated with the relay may be defined, for example, a "paging for relay message". In a manner that includes one or more information from a) to d) above, a paging message as shown in Table 3 may be extended and used. Details of the paging message as shown in Table 3 are expanded and used may be applied in the same manner as described in step 3) of FIG. 15.

Steps 4 to 7) 4) to 7) may be performed in the same manner as steps 6) to 9) of FIG. 17.

For reference, UE-1 may camp to NG-RAN other than UE-2's last serving NG-RAN in step 4), or may resume RRC. In this case, the NG-RAN (ie, the serving NG-RAN of UE-1) in which UE-1 has resumed camping or RRC may not have a UE-2 related context. The NG-RAN (that is, the serving NG-RAN of UE-1) in which UE-1 has resumed this camping or RRC performs an operation of fetching the UE-2 related context from the last serving NG-RAN of UE-2. You can also do it.

For example, an operation in which the serving NG-RAN of UE-1 obtains a context related to UE-2 from the last serving NG-RAN of UE-2 is the serving NG-RAN of UE-1 and the last serving NG of UE-2. It may be performed between -RANs. For another example, the operation of obtaining a UE-2 related context from the last serving NG-RAN of UE-2 of UE-1 may be performed through AMF.

The operation for the serving NG-RAN of UE-1 to obtain a UE-2 related context from the last serving NG-RAN of UE-2 may be performed when UE-1 establishes (or establishes) an RRC connection, or step 9 ) May be performed (eg, the UE context search process of step 2) and step 2) of the example of FIG. 10 may be performed).

When the serving NG-RAN of UE-1 gets the UE-2 related context from the last serving NG-RAN of UE-2, the serving NG-RAN of UE-1 is maintained by the last serving NG-RAN of UE-2. Downlink data to UE-2 may also be imported. Alternatively, when performing step 14), the serving NG-RAN of UE-1 obtains downlink data from the last serving NG-RAN of UE-2 to UE-2, and then delivers it to UE-2 through UE-1. May be.

8 to 14) Steps 8) to 14) may be performed in the same manner as steps 6) to 12) of FIG. 15.

4. Fourth example of disclosure of this specification

In a fourth example of the disclosure of the present specification, operations for supporting MT service to a remote UE by maintaining the relay UE in the RRC_CONNECTED state will be described.

When the UE initiates or activates a UE-to-Network Relay operation, or when the UE needs to provide a network connection service to a remote UE (e.g., when step 4 in FIG. 19 is performed), the UE becomes a relay UE. It can work. The network may maintain a Relay UE (UE-to-Network Relay) in an RRC_CONNECTED state (eg, as described in step 5 of FIG. 19), the Relay UE may be maintained in an RRC_CONNECTED state).

Keeping the relay UE in the RRC_CONNECTED state by the network may mean performing one or more of the following operations:

i) The serving NG-RAN of the Relay UE does not perform the AN release operation for the Relay UE.

ii) The serving NG-RAN of the Relay UE does not initiate an inactivity timer for the Relay UE.

iii) The serving NG-RAN of the Relay UE does not perform the AN release operation for the Relay UE even if the inactivity timer for the Relay UE expires.

iv) Serving of the Relay UE Even if the NG-RAN receives an AN release request for the Relay UE from the AMF, it does not perform the AN release operation for the Relay UE. Additionally, a rejection response may be transmitted to the AMF in response to the AMF's AN release request.

The following drawings are prepared to explain a specific example of the present specification. Since the names of specific devices or names of specific signals/messages/fields described in the drawings are provided by way of example, technical features of the present specification are not limited to specific names used in the following drawings.

Degree 19 is A signal flow diagram according to a fourth example of the disclosure of the present specification is shown.

Referring to FIG. 19, a connection establishment procedure for indirect communication through a relay UE will be described.

0) In the case of an in coverage situation, the Remote UE and the UE-to-Network Relay UE (hereinafter referred to as Relay UE) may independently perform a registration procedure to perform initial registration for the network. If NAS signaling between the remote UE and the network is later exchanged through the Relay UE, the 5G GUTI allocated for the remote UE can be maintained.

1) In the case of an in coverage situation, the remote UE and the relay UE may independently receive service authorization for indirect communication from the network.

If the remote UE is not in coverage, preset information may be used. If necessary, the PCF may update the authorization information for the remote UE after performing step 7).

2 and 3) The remote UE and the relay UE may perform a UE-to-Network Relay UE discovery procedure and a selection procedure.

4) The remote UE may initiate a one-to-one communication connection through the selected relay UE and PC5 by transmitting an indirect communication request message to the relay UE.

5) The relay UE is in the CM_CONNECTED state and must have the authority to perform the relay service, and step 5) may be omitted. In order for the Relay UE to maintain the CM_CONNECTED state, the Relay UE informs the serving AMF (AMF-1) that the Relay UE is playing the role of Reay to handle the relay service of the remote UE, and makes an RRC connection to the NG-RAN. You can tell them to keep.

6) The relay UE may transmit an indirect communication response message to the remote UE.

7) The remote UE can transmit a NAS message to the serving AMF (AMF-2). NAS messages can be encapsulated within RRC messages. The remote UE may transmit an RRC message including a NAS message to the Relay UE through PC5, and the Relay UE may transmit an RRC message to the NG-RAN. The NG-RAN may derive the serving AMF of the Remote UE and transmit a NAS message to this AMF.

For reference, it is assumed that the PLMN of the remote UE is accessible by the PLMN of the relay UE, and the AMF (AMF-1) of the relay UE supports all S-NSSAIs that the remote UE intends to connect to.

When the remote UE does not perform initial registration for the network in step 0), the NAS message transmitted by the remote UE in step 7) may be an initial registration message. Otherwise, the NAS message may be a service request message.

When the remote UE performs initial registration through the relay UE, the serving AMF of the remote UE may perform authentication for the remote UE based on NAS message validation. If necessary, the AMF of the remote UE may check subscription data.

In the case of a service request, a user plane connection of a PDU session may be activated.

8) The remote UE may trigger a PDU session establishment procedure.

9) Data between the remote UE and the UPF may be transmitted through the relay UE and the NG-RAN. The Relay UE can deliver all data messages between the Remote UE and the NG-RAN using a RAN specified L2 relay method.

For reference, when the connection of the relay UE is disconnected (disconnect), the NG-RAN may trigger an AN release procedure for the remote UE, and the remote UE may enter the CM-IDLE state.

For reference, in the example of FIG. 19, except that the Relay UE maintains the RRC_CONNECTED state, the operations described in steps 0) to 8) may be performed before step 0) in the examples of FIGS. 15 to 18 is performed. These are the movements.

According to the disclosure of the present specification, the network and/or the relay UE may support the MT service to the remote UE in consideration of the RRC_INACTIVE state defined in 5GS.

For reference, the operation of a terminal (eg, a remote UE or a relay UE) described in the present specification may be implemented by the devices of FIGS. 20 to 24 to be described below. For example, the terminal (eg, a remote UE or a relay UE) may be the first device 100a or the second device 100b of FIG. 21. For example, the operation of a terminal (eg, a remote UE or a relay UE) described in this specification may be processed by one or more processors 1020a or 1020b. The operation of the UE described herein may be stored in one or more memories 1010a or 1010b in the form of an instruction/program (e.g. instruction, executable code) executable by one or more processors 1020a or 1020b. One or more processors 1020a or 1020b control one or more memories 1010a or 1010b and one or more transceivers 1031a or 1031b, and execute instructions/programs stored in one or more memories 1010a or 1010b to disclose the present specification. It is possible to perform the operation of the terminal (eg, UE) described in the above.

In addition, instructions for performing an operation of a terminal (eg, a remote UE or a relay UE) described in the disclosure of the present specification may be stored in a recording nonvolatile computer-readable storage medium. The storage medium may be included in one or more memories 1010a or 1010b. Further, the instructions recorded in the storage medium may be executed by one or more processors 1020a or 1020b to perform the operation of the terminal (eg, a remote UE or a relay UE) described in the disclosure of the present specification.

For reference, the operation of a network node (eg, AMF, SMF, UPF, UDM, DN, NG-RAN, DN-AAA server, RAUSF, etc.) or a base station (eg, NG-RAN, gNB, eNB, etc.) described in this specification May be implemented by the apparatus of FIGS. 20 to 24 which will be described below. For example, the network node may be the first device 100a or the second device 100b of FIG. 21. For example, the operation of the network node described herein may be processed by one or more processors 1020a or 1020b. The operations of a network node or a base station described herein may be stored in one or more memories 1010a or 1010b in the form of an instruction/program (e.g. instruction, executable code) executable by one or more processors 1020a or 1020b. One or more processors 1020a or 1020b control one or more memories 1010a or 1010b and one or more transceivers 1031a or 1031b, and execute instructions/programs stored in one or more memories 1010a or 1010b to disclose the present specification. The operation of the network node or the base station described above may be performed.

IV. Examples to which the disclosure of this specification is applied

Although not limited thereto, various descriptions, functions, procedures, proposals, methods, and/or operational flow charts of the disclosure of the present specification disclosed in this document are used in various fields requiring wireless communication/connection (eg, 5G) between devices. Can be applied.

Hereinafter, it will be illustrated in more detail with reference to the drawings. In the following drawings/description, the same reference numerals may exemplify the same or corresponding hardware block, software block, or functional block, unless otherwise indicated.

Figure 20 works In the examples It shows a wireless communication system according to.

Referring to FIG. 20, the wireless communication system may include a first device 100a and a second device 100b. The first device 100a and the second device 100b may be wireless communication devices capable of performing wireless communication.

The first device 100a may be the UE described in the disclosure of this specification. Alternatively, the first device 100a is a base station, a network node, a transmitting UE, a receiving UE, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, a connected car, a drone (Unmanned Aerial Vehicle). , UAV), AI (Artificial Intelligence) module, robot, AR (Augmented Reality) device, VR (Virtual Reality) device, MR (Mixed Reality) device, hologram device, public safety device, MTC device, IoT device, medical device, It may be a fintech device (or financial device), a security device, a climate/environment device, a device related to 5G service, or a device related to the fourth industrial revolution field.

The second device 100b may be a network node (eg, AMF or MME) described in the disclosure of the present specification. Alternatively, the second device 100b is a base station, a network node, a transmitting UE, a receiving UE, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, a connected car, a drone (Unmanned Aerial). Vehicle, UAV), AI (Artificial Intelligence) module, robot, AR (Augmented Reality) device, VR (Virtual Reality) device, MR (Mixed Reality) device, hologram device, public safety device, MTC device, IoT device, medical device , Fintech devices (or financial devices), security devices, climate/environment devices, devices related to 5G services, or other devices related to the 4th industrial revolution field.

For example, the UE 100 is a mobile phone, a smart phone, a laptop computer, a digital broadcasting UE device, a personal digital assistants (PDA), a portable multimedia player (PMP), a navigation system, and a slate PC. PC), tablet PC, ultrabook, wearable device, for example, a watch-type UE device (smartwatch), a glass-type UE device (smart glass), HMD (head mounted display)) And the like. For example, the HMD may be a display device worn on the head. For example, HMD can be used to implement VR, AR or MR.

For example, a drone may be a vehicle that is not human and is flying by a radio control signal. For example, the VR device may include a device that implements an object or a background of a virtual world. For example, the AR device may include a device that connects and implements an object or background of a virtual world, such as an object or background of the real world. For example, the MR device may include a device that combines and implements an object or background of a virtual world, such as an object or background of the real world. For example, the hologram device may include a device that implements a 360-degree stereoscopic image by recording and reproducing stereoscopic information by utilizing an interference phenomenon of light generated by the encounter of two laser lights called holography. For example, the public safety device may include an image relay device or an image device wearable on a user's human body. For example, the MTC device and the IoT device may be devices that do not require direct human intervention or manipulation. For example, the MTC device and the IoT device may include a smart meter, a bending machine, a thermometer, a smart light bulb, a door lock, or various sensors. For example, the medical device may be a device used for the purpose of diagnosing, treating, alleviating, treating or preventing a disease. For example, the medical device may be a device used for the purpose of diagnosing, treating, alleviating or correcting an injury or disorder. For example, a medical device may be a device used for the purpose of examining, replacing or modifying a structure or function. For example, the medical device may be a device used for the purpose of controlling pregnancy. For example, the medical device may include a device for treatment, a device for surgery, a device for (extra-corporeal) diagnosis, a device for hearing aid or a procedure. For example, the security device may be a device installed to prevent a risk that may occur and maintain safety. For example, the security device may be a camera, CCTV, recorder, or black box. For example, the fintech device may be a device capable of providing financial services such as mobile payment. For example, the fintech device may include a payment device or a point of sales (POS). For example, the climate/environment device may include a device that monitors or predicts the climate/environment.

The first device 100a may include at least one processor such as a processor 1020a, at least one memory such as a memory 1010a, and at least one transceiver such as a transceiver 1031a. The processor 1020a may perform the functions, procedures, and/or methods described above. The processor 1020a may perform one or more protocols. For example, the processor 1020a may perform one or more layers of a radio interface protocol. The memory 1010a is connected to the processor 1020a and may store various types of information and/or commands. The transceiver 1031a may be connected to the processor 1020a and controlled to transmit and receive radio signals.

The second device 100b may include at least one processor such as a processor 1020b, at least one memory device such as a memory 1010b, and at least one transceiver such as a transceiver 1031b. The processor 1020b may perform the functions, procedures, and/or methods described above. The processor 1020b may implement one or more protocols. For example, the processor 1020b may implement one or more layers of a radio interface protocol. The memory 1010b is connected to the processor 1020b and may store various types of information and/or commands. The transceiver 1031b may be connected to the processor 1020b and controlled to transmit and receive radio signals.

The memory 1010a and/or the memory 1010b may be respectively connected inside or outside the processor 1020a and/or the processor 1020b, or other processors through various technologies such as wired or wireless connection. It can also be connected to.

The first device 100a and/or the second device 100b may have one or more antennas. For example, the antenna 1036a and/or the antenna 1036b may be configured to transmit and receive wireless signals.

Degree 21 is Work In the examples A block diagram of a network node according to the following is illustrated.

In particular, FIG. 21 is a diagram illustrating in detail a case where the base station is divided into a central unit (CU) and a distributed unit (DU).

Referring to FIG. 21, the base stations W20 and W30 may be connected to the core network W10, and the base station W30 may be connected to the neighboring base station W20. For example, the interface between the base stations W20 and W30 and the core network W10 may be referred to as NG, and the interface between the base station W30 and the neighboring base stations W20 may be referred to as Xn.

The base station W30 may be divided into a CU (W32) and DU (W34, W36). That is, the base station W30 may be hierarchically separated and operated. The CU (W32) may be connected to one or more DUs (W34, W36), for example, the interface between the CU (W32) and the DU (W34, W36) may be referred to as F1. The CU (W32) may perform the function of upper layers of the base station, and the DUs (W34, W36) may perform the function of lower layers of the base station. For example, the CU (W32) is a logical node that hosts radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) layers of a base station (eg, gNB) The DU (W34, W36) may be a logical node hosting a radio link control (RLC), a media access control (MAC), and a physical (PHY) layer of the base station. Alternatively, the CU (W32) may be a logical node hosting the RRC and PDCP layers of the base station (eg, en-gNB).

The operation of the DUs W34 and W36 may be partially controlled by the CU W32. One DU (W34, W36) may support one or more cells. One cell can be supported by only one DU (W34, W36). One DU (W34, W36) may be connected to one CU (W32), and one DU (W34, W36) may be connected to a plurality of CUs by appropriate implementation.

Figure 22 works In the examples Follow Of the UE 100 Composition Block diagram .

In particular, the UE 100 shown in FIG. 22 is a diagram illustrating the first device of FIG. 20 in more detail above.

The UE 100 includes a memory 1010, a processor 1020, a transmission/reception unit 1031, a power management module 1091, a battery 1092, a display 1041, an input unit 1053, a speaker 1042, and a microphone ( 1052), a subscriber identification module (SIM) card, and one or more antennas.

The processor 1020 may be configured to implement the proposed functions, procedures and/or methods described herein. Layers of the air interface protocol may be implemented in the processor 1020. The processor 1020 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and/or a data processing device. The processor 1020 may be an application processor (AP). The processor 1020 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of the processor 1020 are SNAPDRAGONTM series processors manufactured by Qualcomm®, EXYNOSTM series processors manufactured by Samsung®, A series processors manufactured by Apple®, HELIOTM series processors manufactured by MediaTek®, INTEL®. It may be an ATOMTM series processor manufactured by or a corresponding next-generation processor.

The power management module 1091 manages power for the processor 1020 and/or the transceiver 1031. The battery 1092 supplies power to the power management module 1091. The display 1041 outputs the result processed by the processor 1020. The input unit 1053 receives an input to be used by the processor 1020. The input unit 1053 may be displayed on the display 1041. A SIM card is an integrated circuit used to securely store an international mobile subscriber identity (IMSI) used to identify and authenticate a subscriber in a mobile phone device such as a mobile phone and a computer and a key associated therewith. You can even store contact information on many SIM cards.

The memory 1010 is operatively coupled to the processor 1020 and stores various pieces of information for operating the processor 610. The memory 1010 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and/or other storage device. When an embodiment is implemented as software, the techniques described in this specification may be implemented as a module (eg, a procedure, a function, etc.) that performs a function described in this specification. Modules may be stored in memory 1010 and executed by processor 1020. The memory 1010 may be implemented inside the processor 1020. Alternatively, the memory 1010 may be implemented outside the processor 1020 and may be communicatively connected to the processor 1020 through various means known in the art.

The transceiver 1031 is operatively coupled to the processor 1020, and transmits and/or receives a radio signal. The transceiver 1031 includes a transmitter and a receiver. The transceiver 1031 may include a baseband circuit for processing radio frequency signals. The transceiver unit controls one or more antennas to transmit and/or receive radio signals. The processor 1020 transmits command information to the transmission/reception unit 1031 to transmit, for example, a radio signal constituting voice communication data in order to initiate communication. The antenna functions to transmit and receive radio signals. When receiving a radio signal, the transceiver 1031 may transmit a signal for processing by the processor 1020 and convert the signal into a baseband. The processed signal may be converted into audible or readable information output through the speaker 1042.

The speaker 1042 outputs a sound-related result processed by the processor 1020. The microphone 1052 receives a sound related input to be used by the processor 1020.

The user inputs command information such as a telephone number, for example, by pressing (or touching) a button of the input unit 1053 or by voice activation using the microphone 1052. The processor 1020 receives the command information and processes to perform an appropriate function, such as dialing a phone number. Operational data may be extracted from the SIM card or the memory 1010. In addition, the processor 1020 may display command information or driving information on the display 1041 for user recognition and convenience.

FIG. 23 is a detailed diagram showing a transmission/reception unit of the first device shown in FIG. 20 or a transmission/reception unit of the device shown in Block diagram .

Referring to FIG. 23, the transmission/reception unit 1031 includes a transmitter 1031-1 and a receiver 1031-2. The transmitter 1031-1 includes a DFT (Discrete Fourier Transform) unit 1031-11, a subcarrier mapper 1031-12, an IFFT unit 1031-13 and a CP insertion unit 1031-14, and a wireless transmission unit 1031 -15). The transmitter 1031-1 may further include a modulator. In addition, for example, a scramble unit (not shown; a scramble unit), a modulation mapper (not shown; modulation mapper), a layer mapper (not shown; layer mapper), and a layer permutator (not shown; layer permutator) may be further included, It may be disposed prior to the DFT unit 1031-11. That is, in order to prevent an increase in the peak-to-average power ratio (PAPR), the transmitter 1031-1 first passes the information through the DFT 1031-11 before mapping the signal to the subcarrier. After performing subcarrier mapping of the signal spread by the DFT unit 1031-11 (or precoded in the same sense) through the subcarrier mapper 1031-12, an Inverse Fast Fourier Transform (IFFT) unit 1031- 13) to make a signal on the time axis.

The DFT unit 1031-11 outputs complex-valued symbols by performing DFT on input symbols. For example, when Ntx symbols are input (however, Ntx is a natural number), the DFT size is Ntx. The DFT unit 1031-11 may be called a transform precoder. The subcarrier mapper 1031-12 maps the complex symbols to each subcarrier in the frequency domain. The complex symbols may be mapped to resource elements corresponding to a resource block allocated for data transmission. The subcarrier mapper 1031-12 may be referred to as a resource element mapper. The IFFT unit 1031-13 outputs a baseband signal for data, which is a time domain signal, by performing IFFT on an input symbol. The CP insertion unit 1031-14 copies a part of the rear part of the baseband signal for data and inserts it into the front part of the baseband signal for data. Inter-symbol Interference (ISI) and Inter-Carrier Interference (ICI) are prevented through CP insertion, so that orthogonality can be maintained even in a multipath channel.

On the other hand, the receiver 1031-2 includes a radio receiver 1031-21, a CP removal unit 1031-22, an FFT unit 1031-23, and an equalization unit 1031-24. The wireless receiving unit 1031 -21, CP removing unit 1031-22, and FFT unit 1031-23 of the receiver 1031-2 are a wireless transmission unit 1031-15 at the transmitting end 1031-1, It performs the reverse function of the CP insertion unit 1031-14 and the IFF unit 1031-13. The receiver 1031-2 may further include a demodulator.

24 illustrates a communication system 1 applied to the disclosure of this specification.

Referring to FIG. 24, a communication system 1 applied to the disclosure of the present specification includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (eg, 5G NR (New RAT), LTE (Long Term Evolution)), and may be referred to as a communication/wireless/5G device. Although not limited thereto, wireless devices include robots 100a, vehicles 100b-1 and 100b-2, eXtended Reality (XR) devices 100c, hand-held devices 100d, and home appliances 100e. ), an Internet of Thing (IoT) device 100f, and an AI device/server 400. For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, and a vehicle capable of performing inter-vehicle communication. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (eg, a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, including HMD (Head-Mounted Device), HUD (Head-Up Display), TV, smartphone, It can be implemented in the form of a computer, wearable device, home appliance, digital signage, vehicle, robot, and the like. Portable devices may include smart phones, smart pads, wearable devices (eg, smart watches, smart glasses), computers (eg, notebook computers, etc.). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors, smart meters, and the like. For example, the base station and the network may be implemented as a wireless device, and the specific wireless device 200a may operate as a base station/network node to another wireless device.

Here, the wireless communication technologies implemented in the wireless devices 100a to 100f and 400 of the present specification and 100 and 200 of FIG. 21 may include LTE, NR, and 6G as well as Narrowband Internet of Things for low-power communication. At this time, for example, the NB-IoT technology may be an example of a Low Power Wide Area Network (LPWAN) technology, and may be implemented in standards such as LTE Cat NB1 and/or LTE Cat NB2, and limited to the above name no. Additionally or alternatively, the wireless communication technology implemented in the wireless devices 100a to 100f and 400 of the present specification and 100 and 200 of FIG. 21 may perform communication based on the LTE-M technology. In this case, as an example, the LTE-M technology may be an example of an LPWAN technology, and may be referred to as various names such as eMTC (enhanced machine type communication). For example, LTE-M technology is 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-Bandwidth Limited (BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) may be implemented in at least one of various standards such as LTE M, and is not limited to the above name. Additionally or alternatively, the wireless communication technology implemented in the wireless devices 100a to 100f, 400, and 100 and 200 in FIG. 21 of the present specification is ZigBee, Bluetooth, and a low-power wide area network (Low Power Wide Area Network, LPWAN) may include at least one of, but is not limited to the above name. As an example, ZigBee technology can generate personal area networks (PANs) related to small/low-power digital communication based on various standards such as IEEE 802.15.4, and may be called various names.

The wireless devices 100a to 100f may be connected to the network 300 through the base station 200. AI (Artificial Intelligence) technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI server 400 through the network 300. The network 300 may be configured using a 3G network, a 4G (eg, LTE) network, or a 5G (eg, NR) network. The wireless devices 100a to 100f may communicate with each other through the base station 200 / network 300, but may perform direct communication (e.g. sidelink communication) without going through the base station / network. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g. V2V (Vehicle to Vehicle)/V2X (Vehicle to Everything) communication). In addition, the IoT device (eg, sensor) may directly communicate with other IoT devices (eg, sensors) or other wireless devices 100a to 100f.

Wireless communication/ connections 150a, 150b, and 150c may be established between the wireless devices 100a to 100f / base station 200 and the base station 200 / base station 200. Here, the wireless communication/connection includes various wireless access such as uplink/downlink communication 150a, sidelink communication 150b (or D2D communication), base station communication 150c (eg relay, Integrated Access Backhaul). This can be achieved through technology (eg 5G NR) Through wireless communication/ connections 150a, 150b, 150c, the wireless device and the base station/wireless device, and the base station and the base station can transmit/receive radio signals to each other. For example, the wireless communication/ connection 150a, 150b, 150c may transmit/receive signals through various physical channels. To this end, based on various proposals disclosed herein, transmission/reception of radio signals At least some of a process of setting various configuration information for, a process of processing various signals (eg, channel encoding/decoding, modulation/demodulation, resource mapping/demapping, etc.), and a resource allocation process may be performed.

Although preferred embodiments have been exemplarily described above, the disclosure of the present specification is not limited to such specific embodiments, and thus modifications, changes, or modifications in various forms within the scope of the spirit and claims of the present specification It can be improved.

In the exemplary system described above, the methods are described on the basis of a flowchart as a series of steps or blocks, but are not limited to the order of the steps described, and certain steps may occur in a different order or concurrently with the steps described above. have. In addition, those skilled in the art will understand that the steps shown in the flowchart are not exclusive, other steps may be included, or one or more steps in the flowchart may be deleted without affecting the scope of the rights.

The claims set forth herein may be combined in a variety of ways. For example, the technical features of the method claims of the present specification may be combined to be implemented as a device, and the technical features of the device claims of the present specification may be combined to be implemented by a method. In addition, the technical characteristics of the method claim of the present specification and the technical characteristics of the device claim may be combined to be implemented as a device, and the technical characteristics of the method claim of the present specification and the technical characteristics of the device claim may be combined to be implemented by a method.

Claims (22)

1. As a method for a base station to perform communication related to a layer 2 relay,

   Receiving downlink data from a User Plane Function (UPF) node to a Remote User Equipment (UE);

   Checking whether the Remote UE and the Relay UEs connected to the Remote UE based on the layer 2 relay are in Radio Resource Control (RRC)_CONNECTED state; And

   Including the step of transmitting a paging message to the Relay UE,

   The paging message is transmitted based on the fact that both the Remote UE and the Relay UE are not in an RRC_CONNECTED state,

   Wherein the paging message is used by the relay UE to transmit a paging message to the remote UE in order to switch the remote UE to an RRC_CONNECTED state.
2. The method of claim 1,

   The Relay UE is in RRC_IDLE state or RRC_INACTIVE state,

   The method of claim 1, wherein the remote UE is in an RRC_IDLE state or an RRC_INACTIVE state.
3. The method of claim 1,

   The paging message,

   At least one of ID information of the Relay UE, ID information of the Remote UE, information instructing the Relay UE to perform paging for the Remote UE, and/or information indicating that downlink data for the Remote UE has occurred. A method comprising information.
4. The method of claim 1,

   The method further comprising receiving an RRC resume request message from the Relay UE.
5. The method of claim 4,

   When the remote UE is in the RRC_INACTIVE state, the RRC resume request message is transmitted by the remote UE in order to switch the remote UE to the RRC_CONNECTED state.
6. The method of claim 4,

   When the Relay UE is in the RRC_INACTIVE state, the RRC resume request message is transmitted by the Relay UE in order to switch the Relay UE to the RRC_CONNECTED state.
7. The method of claim 4,

   In response to the RRC resume request message, the method further comprising transmitting an RRC resume message to the relay UE.
8. The method of claim 7,

   The method further comprising receiving an RRC resume complete message from the Remote UE via the Relay UE.
9. The method of claim 8,

   The method further comprising transmitting downlink data to the remote UE to the relay UE based on the reception of the RRC resume complete message.
10. As a method for a relay user equipment (UE) to perform communication related to a layer 2 relay,

    Receiving a paging message from a base station;

    Transmitting an RRC setup request message or an RRC resumption request message to the base station based on the Relay UE being in the Radio Resource Control (RRC)_IDLE state or the RRC_INACTIVE state; And

    And transmitting a paging message to the remote UE based on the paging message related to downlink data to the relay UE and the connected remote UE based on the layer 2 relay.
11. The method of claim 10,

    The method of claim 1, wherein the remote UE is in an RRC_IDLE state or an RRC_INACTIVE state.
12. The method of claim 11,

    Receiving an RRC setup request message from the remote UE when the remote UE is in the RRC_IDLE state; And

    The method further comprising transmitting the RRC setup request message transmitted by the remote UE to the base station.
13. The method of claim 12,

    Receiving an RRC setup message from the base station in response to the RRC setup request message transmitted by the Remote UE; And

    The method further comprising transmitting the received RRC setup message to the remote UE
14. The method of claim 11,

    When the remote UE is in the RRC_INACTIVE state, receiving an RRC resume request message from the remote UE; And

    The method further comprising transmitting the RRC resume request message transmitted by the remote UE to the base station.
15. The method of claim 14,

    Receiving an RRC resume message in response to the RRC setup resume message transmitted by the Remote UE from the base station; And

    The method further comprising transmitting the received RRC resume message to the remote UE.
16. The method of claim 10,

    The paging message,

    At least one of ID information of the Relay UE, ID information of the Remote UE, information instructing the Relay UE to perform paging for the Remote UE, and/or information indicating that downlink data for the Remote UE has occurred. A method comprising information.
17. The method of claim 16,

    The paging message is ID information of the Relay UE, ID information of the Remote UE, information instructing the Relay UE to perform paging for the Remote UE, and/or information notifying that downlink data for the Remote UE has occurred. Based on including at least one of the information, determining that the paging message is related to downlink data to the connected Remote UE based on the Relay UE and a Layer 2 Relay.
18. In the base station performing communication related to a layer 2 relay,

    At least one processor; And

    It includes at least one memory that stores instructions and is operably electrically connected to the at least one processor,

    The operation performed based on the instruction being executed by the at least one processor is:

    Receiving downlink data from a User Plane Function (UPF) node to a Remote User Equipment (UE);

    Checking whether the Remote UE and the Relay UEs connected to the Remote UE based on the layer 2 relay are in Radio Resource Control (RRC)_CONNECTED state; And

    Including the step of transmitting a paging message to the Relay UE,

    The paging message is transmitted based on the fact that both the Remote UE and the Relay UE are not in an RRC_CONNECTED state,

    The paging message, in order to switch the remote UE to the RRC_CONNECTED state, the base station characterized in that the relay UE is used to transmit a paging message to the remote UE.
19. In Relay User Equipment (UE) that performs communication related to Layer 2 Relay,

    At least one processor; And

    It includes at least one memory that stores instructions and is operably electrically connected to the at least one processor,

    The operation performed based on the instruction being executed by the at least one processor is:

    Receiving a paging message from a base station;

    Transmitting an RRC setup request message or an RRC resumption request message to the base station based on the Relay UE being in the Radio Resource Control (RRC)_IDLE state or the RRC_INACTIVE state; And

    And transmitting a paging message to the remote UE based on the paging message related to downlink data to the relay UE and the connected remote UE based on the layer 2 relay.
20. The method of claim 19,

    The relay UE is an autonomous driving device that communicates with at least one of a mobile terminal, a network, and an autonomous driving vehicle other than the relay UE.
21. As an apparatus in mobile communication,

    At least one processor; And

    It includes at least one memory that stores instructions and is operably electrically connected to the at least one processor,

    The operation performed based on the instruction being executed by the at least one processor is:

    Identifying a paging message transmitted from the base station;

    Generating an RRC setup request message or an RRC resumption request message based on the device being in a Radio Resource Control (RRC)_IDLE state or an RRC_INACTIVE state; And

    And generating a paging message to be transmitted to the remote UE based on the paging message related to downlink data to the connected remote UE based on the layer 2 relay with the device.
22. A non-volatile computer-readable storage medium storing instructions,

    The instructions, when executed by one or more processors, cause the one or more processors to:

    Identifying a paging message transmitted from the base station;

    Generating an RRC setup request message or an RRC resume request message based on the processor being in a Radio Resource Control (RRC)_IDLE state or an RRC_INACTIVE state; And

    A nonvolatile computer-readable storage medium for performing the step of generating a paging message to be transmitted to the remote UE based on the paging message associated with downlink data to the connected remote UE based on the processor and the layer 2 relay.

Images