Processing method for core network device and terminal

Abstract

To provide a core network device and a communication method capable of appropriately performing policy control in multicast and / or broadcast communication.SOLUTION: A core network device that manages an MBS session includes: a control unit that, when setting up an MBS session, determines whether or not it is necessary to inquire of a first core network device that controls a policy about the policy to be applied to the MBS session; and a communication unit that, when it is necessary to inquire of the first core network device about the policy, acquires specification information for specifying the first core network device from a second core network device that detects functions present in the core network. The control unit specifies the first core network device on the basis of the specification information. The communication unit transmits a message to the specified first core network device to inquire about the policy to be applied to the MBS session.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a core network device and a communication method.

Background Art

[0002] In the Third Generation Partnership Project (3GPP), which is an international standards organization, Release 15 of New Radio (NR), which is the fifth generation (5G) Radio Access Technology (RAT), has been standardized as a successor to Long Term Evolution (LTE), which is the 3.9th generation RAT, and LTE-Advanced, which is the 4th generation RAT (for example, Non-Patent Document 1).

[0003] Also, Release 15 of the 5G Core Network (5GC), which is the fifth generation CN, has been standardized as a successor to the Evolved Packet Core (EPC), which is the fourth generation Core Network (CN) (for example, Non-Patent Document 2).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Currently, 3GPP is considering supporting Multicast Broadcast Service (MBS), which is a transmission service for multicast data and / or broadcast data. MBS in 5GC is also called 5MBS etc.

[0006] In 5GC, policy control in unicast communication (one-to-one communication) is realized using a function called Policy Control Function (PCF). It is also desirable to perform appropriate policy control in multicast and / or broadcast communication as well as in unicast communication.

[0007] This disclosure has been made in view of such circumstances, and an object thereof is to provide a core network device and a communication method that enable appropriate policy control in multicast and / or broadcast communication.

Means for Solving the Problems

[0008] A core network device according to an aspect of the present disclosure is a core network device that manages a Multicast Broadcast Service (MBS) session. When setting the MBS session, a control unit that confirms whether it is necessary to inquire about the policy applied to the MBS session from a first core network device that controls the policy, and when it is necessary to inquire about the policy from the first core network device, a communication unit that acquires specific information for identifying the first core network device from a second core network device that detects functions existing in the core network. The control unit identifies the first core network device based on the specific information, and the communication unit transmits a message for inquiring about the policy applied to the MBS session to the identified first core network device.

Effects of the Invention

[0009] According to the present disclosure, in multicast and / or broadcast communication, a core network device and a communication method capable of appropriately performing policy control can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicate descriptions are omitted.

[0012] FIG. 1 is a diagram showing an example of the outline of the communication system according to the present embodiment. As shown in FIG. 1, the communication system 1 includes a terminal 10, a base station 20, and a core network (CN) 30, and provides MBS.

[0013] The terminal 10 is a predetermined terminal or device such as, for example, a smartphone, a personal computer, an in-vehicle terminal, an in-vehicle device, a stationary device, a telematics control unit (TCU), etc. The terminal 10 may be called a user equipment (UE), a mobile station (MS), a user terminal, a radio apparatus, a subscriber terminal, an access terminal, etc. The terminal 10 may be mobile or fixed.

[0014] The terminal 10 is configured to be able to communicate with at least one of, for example, LTE, LTE-Advanced, NR, etc. as a radio access technology (RAT) RAT for the base station 20, but is not limited thereto, and may be configured to be able to communicate using a RAT after the 6th generation. Further, the terminal 10 is not limited to the 3GPP access network defined by 3GPP as described above, and may access the base station 20 via a non-3GPP access network such as Wi-Fi, for example.

[0015] The base station 20 forms one or more cells and communicates with the terminal 10 using the cells. The base station 20 may be referred to as a gNodeB (gNB), an en-gNB, a Radio Access Network (RAN), an Access Network (AN), a Next Generation-Radio Access Network (NG-RAN) node, a low-power node, a Central Unit (CU), a Distributed Unit (DU), a gNB-DU, a Remote Radio Head (RRH), an Integrated Access and Backhaul / Backhauling (IAB) node, etc. The base station 20 is not limited to a single node and may be composed of a plurality of nodes (for example, a combination of a lower node such as a DU and a higher node such as a CU).

[0016] Note that the number of the terminal 10 and the base station 20 shown in FIG. 1 may be one or more. Of course, one or more terminals 10 may be connected to one base station 20.

[0017] CN30 is, for example, 5GC, but is not limited thereto, and may be, for example, EPC or a core network of the sixth generation or later. CN30 includes various functions such as, for example, Access and Mobility Management Function (AMF) 31, Session Management Function (SMF) 32, User Plane Function (UPF) 33, Multicast Broadcast (MB)-SMF 34, Multicast Broadcast (MB)-UPF 35, Network Exposure Function (NEF) / Multicast Broadcast Service Function (MBSF) 36, Application Function (AF) 37, Multicast Broadcast Service Transport Function (MBSTF) 38, PCF 39, Binding Support Function (BSF) 40, Unified Data Repository (UDR) 41, Network Repository Function (NRF) 42, etc. Note that these functions are collectively called Network Function (NF). Also, a distinguishable instance of each function (that is, the actual entity of the NF that is actually operating in a physical or virtual device) may be referred to as an NF instance.

[0018] Note that the functions included in CN30 are not limited to those shown in FIG. 1. Some of the functions shown in FIG. 1 may be omitted from CN30, or functions not shown may be included. Also, the names of the functions shown in FIG. 1 are merely examples, and other names may be used if they have equivalent or similar functions. A device in which one or more of the functions included in CN30 are implemented may be referred to as a core network device. Also, the device is not necessarily limited to a physical device, and may be a virtual device realized on a virtual OS (Operating System).

[0019] AMF31 is a function that manages the access and / or mobility of terminal 10. AMF31 performs processing related to the C plane (e.g., registration management, connection management, mobility management), etc. In addition, AMF31 performs processing related to the Non-access stratum (NAS) and transmits and / or receives NAS messages to / from terminal 10.

[0020] SMF32 is a function that manages sessions and controls, for example, the establishment, update, and release of sessions.

[0021] UPF33 is a function that serves as a connection point to a Data Network (DN) (not shown) and performs, for example, packet routing, forwarding, etc. UPF33 transmits and receives data to / from terminal 10 via a PDU session. UPF33 is the first user plane device that performs processing related to the U plane.

[0022] MB-SMF34 is a function that manages sessions for MBS (hereinafter referred to as "MBS sessions") and controls, for example, the establishment, update, and release of MBS sessions (including QoS control). MBS sessions are also referred to as Multicast Broadcast (MB) sessions, etc. In addition, MB-SMF34 configures MB-UPF35 to control the flow of MBS data based on the local policy held by MB-SMF34 or the MBS policy rules provided by PCF39. Also, MB-SMF34 assigns and releases a Temporary Mobile Group Identity (TMGI).

[0023] Note that the participation (join) in the MBS session may be accepted by means of an NAS message from the terminal 10 to the AMF 31 (e.g., UL NAS MB Session Join Request), a request message from the AMF 31 to the MB-SMF 34 (e.g., MB Session Request), a response message from the MB-SMF 34 to the AMF 31 in response to the request message (e.g., MB Session Response), and an NAS message from the AMF 31 to the terminal 10 in response to the response message (e.g., DL NAS MB Session Join Accept). The MBS session or the stream of MBS data may be identified by a predetermined identifier (e.g., MBS Session ID).

[0024] The MBS Session ID may be a TMGI or a source specific IP multicast address. Note that the source specific IP multicast address may be composed of two addresses, i.e., an IP unicast address (source address for identifying the source of the multicast service) and an IP multicast address (destination address for identifying the multicast service).

[0025] The MB-UPF 35 is a function for controlling the flow of MBS data from the MBSTF 38 or a DN (not shown). The downstream MBS data from the MBSTF 38 or a DN (not shown) is transmitted from the MB-UPF 35 to the base station 20 or the UPF 33.

[0026] The NEF 36b provides an interface to the AF 37. The MBSF 36a selects the MB-SMF 34 that provides the MBS session, realizes communication between the AF 37 and the MB-SMF 34, and / or controls the MBSTF 38, etc. The MBSF 36a can be collocated with the NEF 36b. In the following description, when the MBSF 36a is collocated with the NEF 36b, it is described as the NEF / MBSF 36.

[0027] By providing service information including QoS requirements to the 5GC, AF37 requests the 5GC for multicast services or broadcast services. AF37 may be a function provided by, for example, a content provider.

[0028] MBSTF38 has a general packet transmission function and operates as a media anchor for MBS data.

[0029] When dynamic policy and charging control (Dynamic PCC) is required, PCF39 performs QoS handling in the MBS session. In addition, PCF39 provides the policy information applied to the MBS session (hereinafter referred to as "MBS policy") to MB-SMF34. Dynamic PCC means that policy control and charging control can be flexibly changed according to the network state and / or service offering content, etc., rather than being static (fixed). Dynamic PCC may also be referred to as "dynamic policy control". Also, PCF39 may obtain the MBS policy from UDR41 existing in the same PLMN (Public Land Mobile Network) as PCF39. Among PCF39, the PCF39 that controls the policy of the MBS session may also be referred to as MB (Multicast Broadcast)-PCF.

[0030] BSF40 stores internal information related to the PDU session (including the MBS session) (user identifier, DNN (Data Network Name), UE address, S-NSSAI (Single-Network Slice Selection Assistance Information), selected PCF address, etc.). PCF39 accesses BSF40 and performs registration, update, deletion, etc. of the information stored in BSF40.

[0031] UDR41 provides a policy data storage and search function for PCF39.

[0032] NRF42 detects NFs existing in the core network. Also, when receiving a detection request for an NF from an NF instance, NRF42 detects one or more NF instances that match the detection request, and provides information related to the one or more detected NF instances to the NF instance that sent the detection request. The information related to the NF instance may be referred to as an "NF profile" or "information for identifying an NF". The NF profile includes a plurality of information (for example, parameters) related to the NF instance. For example, it includes an NF instance ID, NF type, network slice related ID (S-NSSAI, NSI ID (Network Slice Instance Identifier), etc.), FQDN (Fully Qualified Domain Name) or IP address of the NF, NF capacity information, NF priority information, location information of the NF instance, TAI (Tracking Area Identity), NF load information, etc. Note that the content of the information included in the NF profile differs depending on the NF.

[0033] Here, the "Discovery" of an NF means that an NF instance within CN30 discovers other NF instances to communicate with (which may also be referred to as discovering candidates for NF instances). The discovery of an NF can be performed by the NF instance querying the NRF42. Also, the "Selection" of an NF means that the NF instance selects one or more NF instances from among the one or more detected NF instances. For example, the NF instance may select one or more NF instances based on information related to the one or more NF instances detected by the NRF42 and received from the NRF42. The selection criteria for NF instances may be set in advance as local information within the NF, or may be determined based on operator policies, etc. There are a large number of NF instances within 5GC. By using the mechanism for performing NF discovery and selection, an NF can identify the NF instance to communicate with from among a large number of NF instances.

[0034] <Method for Transmitting MBS Data> In the communication system 1 as described above, MBS data is delivered to the terminals 10 registered by messages (e.g., join or leave messages) of a protocol for multicast distribution control (e.g., Internet Group Management Protocol (IGMP) or Multicast Listener Discovery (MLD)). As transmission modes of MBS data, an individual mode and a shared mode are being considered for support.

[0035] In the individual mode, the MBS data (a single copy of MBS data) received at CN30 is transmitted to each terminal 10 via a PDU session for each terminal 10 (e.g., a single unicast PDU session with each terminal 10). The individual mode is also referred to as the first transmission mode, Individual MBS Traffic delivery, 5GC Individual MBS traffic delivery method, Ind-mode, etc. A terminal 10 in the individual mode can receive MBS data regardless of whether the base station 20 forming the serving cell supports MBS.

[0036] In the shared mode, the MBS data (a single copy of MBS data) received at CN30 is transmitted to the base station 20 via Shared Transport with the base station 20, and is transmitted from the base station 20 to the subordinate terminals 10 by Point To Point (PTP) or Point To Multi-point (PTM). The shared mode is also referred to as the second transmission mode, Shared MBS Traffic delivery, 5GC Shared MBS traffic delivery method, Shared-mode, etc. A terminal 10 in the shared mode can receive MBS data when the base station 20 forming the serving cell supports MBS.

[0037] FIG. 2 is a diagram showing an example of a transmission mode of MBS data according to the present embodiment. As shown in FIG. 2, the MBS data from a DN (not shown) is received at the MB-UPF35 in the CN30.

[0038] In the individual mode, MB-UPF35 transfers the received MBS data to UPF33 via the N9 tunnel. Note that the N9 tunnel is a tunnel of the N9 interface. UPF33 replicates the MBS data received from MB-UPF35 and transmits it to each terminal 10 via the PDU sessions individually configured with each terminal 10. In the individual mode, even when the terminal 10 hands over to a base station 20 that does not support MBS, the terminal 10 can continue to receive MBS data.

[0039] On the other hand, in the shared mode, MB-UPF35 transmits the received MBS data to the base station 20 via shared transport. The shared transport is a shared tunnel within CN30 and is also called a shared downlink CN tunnel, N3 tunnel, etc. The base station 20 transmits the MBS data received from MB-UPF35 via the shared transport to the subordinate terminals 10 by PTM or PTP. In the shared mode, since the MBS data for a large number of terminals 10 is bundled into one stream, the overhead of the U plane within CN30 can be reduced compared to the individual mode.

[0040] The MBS session includes a broadcast session and a multicast session. In the multicast session, the transmission of MBS data (MBS traffic) is performed using both the individual mode and the shared mode. On the other hand, in the broadcast session, the transmission of MBS data (MBS traffic) is performed using only the shared mode.

[0041] <Provisioning of MB Service> When CN30 provides MBS, it first performs MBS Session Configuration and Service Announcement for terminal 10, and then establishes the MBS Session. In the stage of configuring the MBS session, information about the MBS session is set in each NF of the 5GC, but resource reservation for the user plane for base station 20 is not performed, and MBS data cannot be transmitted. In the service announcement, CN30 means notifying terminal 10 of the information necessary to receive MBS data. When the MBS session is established, resources of the 5GC and base station 20 for the MBS session are reserved, and MBS data transmission becomes possible.

[0042] <MBS Session Configuration Procedure> FIG. 3 and FIG. 4 are diagrams showing an example of the MBS session configuration procedure according to this embodiment. The configuration of the MBS session is executed before the procedure for establishing the MBS session.

[0043] In FIG. 3, the processing procedures of steps S100 to S160 are executed when the TMGI is used as the MBS session ID and it is necessary to allocate the TMGI in advance before configuring the MBS session. That is, the processing procedures of steps S100 to S160 correspond to the procedure for allocating the TMGI, and the processing procedures after step S170 correspond to the procedure for configuring the MBS session.

[0044] In step S100, AF37 transmits a message for requesting the allocation of TMGI (for example, TMGI allocation request) to NEF / MBSF36 in order to request the allocation of TMGI for identifying a new MBS session.

[0045] In step S110, the NEF / MBSF36 performs a confirmation (Authorization) on whether the AF37 has the authority to execute the processing procedure of step S100. If it has the authority, it proceeds to the processing procedure of step S120.

[0046] In step S120, the NEF / MBSF36 either queries the NRF42 or performs the detection and selection of the MB-SMF34 based on its own local configuration.

[0047] For example, the NEF / MBSF36 obtains information about candidates of MB-SMF34 capable of performing the allocation of TMGI (e.g., a list of MB-SMF profiles) from the NRF42, and based on the obtained information, selects one MB-SMF34 that requests the allocation of TMGI.

[0048] In step S130, the NEF / MBSF36 sends a message (e.g., TMGI allocation request) requesting the allocation of TMGI to the selected one MB-SMF34.

[0049] In step S140, the MB-SMF34 performs the allocation of TMGI, includes the allocated TMGI in the TMGI allocation response message, and sends it to the NEF / MBSF36.

[0050] In step S150, the NEF / MBSF36 includes the TMGI allocated by the MB-SMF34 in the TMGI allocation response message and sends it to the AF37.

[0051] In step S160, the AF37 performs service notification to the terminal 10 (not shown). For example, the AF37 notifies the terminal 10 of the MBS session ID (here, the allocated TMGI) and other information (MBS service area, session description information, etc.).

[0052] In step S170, AF37 sends a message requesting an MBS session (e.g., MBS Session Request or Multicast Session Request) containing information related to the MBS session (MBS session ID, service type (e.g., either broadcast service or multicast service), and MBS information, etc.) to NEF / MBSF36. Note that if a TMGI is assigned as the MBS session ID by the processing procedures of steps S100 to S160, the TMGI is included in the MBS session request. The MBS information may include MBS service area information, start time and end time of the MBS, etc. NEF / MBSF36 checks (Authorization) whether AF37 has the authority to execute the processing procedure of step S170, and if it has the authority, proceeds to the processing procedure of step S180.

[0053] In step S180, NEF / MBSF36 queries the NRF42 or detects and selects the MB-SMF34 based on its own settings. If the TMGI is assigned in the processing procedure of step S130, NEF / MBSF36 may select the MB-SMF34 that assigned the TMGI.

[0054] In step S190, NEF / MBSF36 sends a message (e.g., Nmbsmf_MBSSession_Create Request) requesting the creation of an MBS session to the selected MB-SMF34. The message includes the MBS session ID, TMGI assignment instruction, service type, MBS service area information notified by AF37 in step S170, etc.

[0055] In step S200, when the MBS session ID is the source-specific IP multicast address in step S190, MB-SMF34 performs the allocation of TMGI. Also, MB-SMF34 may update the NF profile of MB-SMF34 stored in NRF42 using the MBS session ID.

[0056] In step S210, MB-SMF34 sends an MBS Policy Association Request message containing the MBS session ID to PCF39.

[0057] In step S220, PCF39 sends a message (e.g., Management register) to register with BSF40 that PCF39 will handle the multicast session. The message includes the MBS session ID and the PCF identification information of PCF39 itself (e.g., NF instance ID of PCF39, PCF ID, FQDN, and / or IP address, etc.).

[0058] In step S230, PCF39 accesses UDR41 to obtain the pre-configured MBS policy associated with the MBS session ID.

[0059] In step S240, PCF39 sends an MBS Policy Association Response message (e.g., MBS Policy Association Response) containing the MBS policy associated with the MBS session ID obtained in step S230 to MB-SMF34. The MBS policy may include, for example, information regarding QoS applied to the MBS session, information regarding the priority of the MBS service, information regarding the area where the MBS session is provided, information regarding the date and time or time zone when the MBS session is provided, and / or information regarding the network slice that provides the MBS session, etc.

[0060] In step S250, MB-SMF34 selects MB-UPF35 and sends a message (Session Request) requesting reservation of resources for transmitting the user plane (i.e., MBS data to be sent to terminal 10) to the selected MB-UPF35. At this time, MB-SMF34 may notify MB-UPF35 of the MBS policy to be applied when transmitting MBS data to terminal 10 by including the MBS policy in the message and sending it to MB-UPF35.

[0061] In step S260, MB-UPF35 sends a session response message (e.g., Session Response) to MB-SMF34.

[0062] In step S270, MB-SMF34 sends a generation response message for the MBS session (e.g., Nmbsmf_MBSSession_Create Response) to NEF / MBSF36. The message includes the MBS session ID and information indicating whether the allocation of resources for transmitting MBS data was successful or failed.

[0063] In step S280, NEF / MBSF36 may send a detection request message (e.g., Man Discovery Request) including the MBS session ID to BSF40 to detect PCF39 that processes the MBS session having the MBS session ID notified in step S270.

[0064] In step S290, BSF40 sends the PCF identification information of PCF39 associated with the notified MBS session ID to NEF / MBSF36. The PCF identification information sent to NEF / MBSF36 is the PCF identification information registered with BSF40 in the processing procedure of step S220 in Figure 3.

[0065] In step S300, the NEF / MBSF36 may send a message (e.g., MBS Policy Association) requesting the assignment of an MBS policy to the PCF39 notified in step S290.

[0066] In step S310, the PCF39 may, if necessary, send a message (e.g., MBS Policy Association Update) requesting an update of the MBS policy, including the updated MBS policy, to the MB-SMF34.

[0067] In step S320, if the MB-SMF34 updates the MBS policy as necessary, it may send a message (e.g., Session Update) requesting an update of the MBS session to the MB-UPF35.

[0068] In step S330, if necessary, the NEF / MBSF36 may send a session request message (e.g., Session Request) to the MBSTF38.

[0069] In step S340, if necessary, the MBSTF38 may notify the NEF / MBSF36 of a session response message (e.g., Session Response).

[0070] In step S350, the NEF / MBSF36 sends a session response message (Multi Session Response) including various parameters (such as MBS session ID, etc.) to the AF37.

[0071] In step S360, the AF37 performs service notification to the terminal 10 (not shown).

[0072] <Processing Procedures for PCF Detection and Selection> Next, in the MBS session setup procedure, the specific processing procedure for detecting and selecting the PCF 39 will be described. In the following description, the same reference numerals may be assigned to the same processing procedures as those in the descriptions of FIGS. 3 and 4, and the descriptions may be omitted.

[0073] (Processing Procedure 1-1) In Processing Procedure 1-1, during the processing procedure of allocating the TMGI, the PCF 39 is detected and selected.

[0074] FIG. 5 is a sequence diagram showing an example of Processing Procedure 1-1 regarding the detection and selection of the PCF.

[0075] In step S120, the NEF / MBSF 36 makes an inquiry to the NRF 42 or performs detection and selection of the MB-SMF 34 based on the local configuration of the MB-SMF 34 itself.

[0076] In step S121, the NRF 42 that has received the inquiry from the NEF / MBSF 36 accesses the UDR 41 and checks whether it is necessary to inquire about the MBS policy to the PCF 39 when setting up the MBS session for allocating the TMGI. The NRF 42 notifies the NEF / MBSF 36 of the confirmation result (i.e., information indicating whether it is necessary to inquire about the MBS policy to the PCF 39).

[0077] In step S131, the NEF / MBSF36 sends a message (e.g., TMGI allocation request) requesting the allocation of TMGI to one selected MB-SMF34. When receiving from the NRF42 the confirmation result that it is necessary to query the PCF39 about the MBS policy, the NEF / MBSF36 includes in the message the MBS policy and information indicating that it is necessary to query the PCF39 about the MBS policy (hereinafter referred to as "PCF usage information" or "PCF information"). On the other hand, when receiving from the NRF42 the confirmation result that it is not necessary to query the PCF39 about the MBS policy, the NEF / MBSF36 sends the message without including the "PCF usage information".

[0078] In step S132, when the MB-SMF34 recognizes that the message requesting the allocation of TMGI includes PCF usage information, it recognizes that it is necessary to query the PCF39 about the MBS policy. When the MB-SMF34 recognizes that the message requesting the allocation of TMGI does not include PCF usage information, it recognizes that it is not necessary to query the PCF39 about the MBS policy.

[0079] When recognizing that it is necessary to query the PCF39 about the MBS policy, the MB-SMF34 detects and selects the PCF39 by querying the NRF42. For example, the MB-SMF34 receives from the NRF42 the NF profiles (e.g., a list of NF profiles of candidate PCFs 39) for one or more PCFs 39 detected by the NRF42, and based on the one or more received NF profiles and the information locally set within the MB-SMF34, or based on the one or more received NF profiles and the operator's policy, it may select one PCF39 for performing the policy control of the MBS session to be set. The locally set information or the operator's policy may define the NF profiles to be used for the selection of the PCF39 and the method or criteria for selecting the PCF39 using the NF profiles.

[0080] For example, the NF profile for PCF39 includes information indicating AF37 associated with PCF39, and MB-SMF34 may select the PCF39 associated with AF37 that requested the setup of the MBS session from among the multiple PCF39s detected by NRF42. That is, the locally set information or the operator's policy may define a method of "selecting the PCF39 associated with AF37 that requested the setup of the MBS session".

[0081] Also, for example, the NF profile for PCF39 includes information indicating the service type of MBS (broadcast service or multicast service) associated with the PCF39, and MB-SMF34 may select the PCF39 associated with the service type required in the MBS session to be set up. That is, the locally set information or the operator's policy may define a method of "selecting the PCF39 associated with the service type required in the MBS session to be set up".

[0082] When the selection of PCF39 is completed, MB-SMF34 stores the PCF identification information (such as the NF instance ID of PCF39, PCF ID, FQDN, and / or IP address, etc.) of the selected PCF39.

[0083] In step S211, MB-SMF34 sends a MBS Policy Association Request message including the MBS session ID to the PCF39 selected in the processing procedure of step S131.

[0084] (Processing Procedure 1-2) In Processing Procedure 1-2, during the processing procedure of setting up the MBS session, the detection and selection of PCF39 are performed.

[0085] FIG. 6 is a sequence diagram showing an example of Processing Procedure 1-2 regarding the detection and selection of PCF.

[0086] In step S180, NEF / MBSF36 inquires NRF42 or performs detection and selection of MB-SMF34 based on its own settings.

[0087] In step S181, NRF42 that has received an inquiry from NEF / MBSF36 accesses UDR41 and checks whether it is necessary to inquire PCF39 about the MBS policy when setting up an MBS session for allocating TMGI. NRF42 notifies NEF / MBSF36 of the check result (i.e., information indicating whether it is necessary to inquire PCF39 about the MBS policy).

[0088] In step S191, NEF / MBSF36 sends a message (e.g., Nmbsmf_MBSSession_Create Request) requesting generation of an MBS session to the selected MB-SMF34. The message includes an MBS session ID, a TMGI allocation instruction, a service type, MBS service area information notified by AF37 in step S170, etc. Also, when receiving from NRF42 the check result indicating that it is necessary to inquire PCF39 about the MBS policy, NEF / MBSF36 includes in the message information indicating that it is necessary to inquire PCF39 about the MBS policy (hereinafter referred to as "PCF usage information" or "PCF information"). On the other hand, when receiving from NRF42 the check result indicating that there is no need to inquire PCF39 about the MBS policy, NEF / MBSF36 sends the message without including "PCF usage information".

[0089] In step S195, when the PCF usage information is included in the message requesting the generation of the MBS session, MB-SMF34 recognizes that it is necessary to query the MBS policy from PCF39. When the PCF usage information is not included in the message requesting the generation of the MBS session, MB-SMF34 recognizes that it is not necessary to query the MBS policy from PCF39. When recognizing that it is necessary to query the MBS policy from PCF39, MB-SMF34 detects and selects PCF39 by querying NRF42. The method for detecting and selecting PCF39 is the same as the processing procedure of step S132 in FIG. 5, so the description is omitted. When the selection of PCF39 is completed, MB-SMF34 holds the PCF identification information (for example, NF instance ID, PCF ID, FQDN, and / or IP address, etc.) of the selected PCF39. Also, MB-SMF34 may store the PCF identification information of the selected PCF39, for example, in the MBS session context (MBS Session context).

[0090] The processing procedure of step S211 is the same as that in FIG. 5, so the description is omitted.

[0091] (Processing procedure 2) In processing procedure 2, during the processing procedure of setting the MBS session, PCF39 is detected and selected. However, different from processing procedures 1-1 and 1-2, MB-SMF34, rather than NRF42, checks whether it is necessary to query the MBS policy from PCF39.

[0092] FIG. 7 and FIG. 8 are sequence diagrams showing an example of processing procedure 2 related to the detection and selection of PCF.

[0093] In step S192, when setting up the MBS session, MB-SMF34 needs to confirm whether it is necessary to query the MBS policy from PCF39. For example, if information regarding the MBS policy is set in MB-SMF34 itself, MB-SMF34 may recognize that there is no need to query the MBS policy from PCF39. Also, if no information regarding the MBS policy is set in MB-SMF34, MB-SMF34 may recognize that it is necessary to query the MBS policy from PCF39.

[0094] Also, for example, if information indicating that the execution of dynamic PCC is necessary is set in MB-SMF34, MB-SMF34 may recognize that it is necessary to query the MBS policy from PCF39. Also, if no information indicating that the execution of dynamic PCC is necessary is set in MB-SMF34, MB-SMF34 may recognize that there is no need to query the MBS policy from PCF39.

[0095] Since the processing procedures of step S195 and step S211 are the same as those in FIG. 5 and FIG. 6, the description thereof is omitted.

[0096] In step S271, MB-SMF34 sends a generation response message for the MBS session (e.g., Nmbsmf_MBSSession_Create Response) to NEF / MBSF36. This message includes the MBS session ID, information indicating success or failure in allocating resources for transmitting MBS data, and the PCF identification information of PCF39 selected in the processing procedure of step S195. The PCF identification information may be, for example, the NF instance ID of PCF39, PCF ID, FQDN, and / or IP address, etc.

[0097] Since NEF / MBSF36 has received the PCF identification information of PCF39 in the processing procedure of step S271, the processing procedures of step S280 and step S290 may be omitted.

[0098] In step S301, the NEF / MBSF36 may send a message (e.g., MBS Policy Association) requesting the allocation of an MBS policy to the PCF39 notified in step S271.

[0099] <Variation of the processing procedure for PCF detection and selection> The PCF usage information may be information indicating a binary choice of whether it is necessary to inquire about the MBS policy from the PCF39. In this case, the PCF usage notification may be, for example, 1-bit information. For example, it may be "1" when it is necessary to inquire about the PCF39, and "0" when it is not necessary to inquire about the PCF39.

[0100] In the processing procedures of steps S120 and S180 in FIG. 5, when the NEF / MBSF36 confirms that it is necessary to inquire about the MBS policy from the PCF39, it may perform the detection and selection of the PCF39 by inquiring about the NRF42. Further, the NEF / MBSF36 may include information about the selected PCF39 in the message requesting the allocation of the TMGI instead of (or in addition to) the PCF usage information and send it to the MB-SMF34. That is, the detection and selection of the PCF39 may be performed by the NEF / MBSF36 instead of the MB-SMF34. The MB-SMF34 may omit the processing procedures of step S132 or step S195.

[0101] <Hardware configuration> FIG. 9 is a diagram showing an example of the hardware configuration of each device in the communication system according to the present embodiment. Each device in the communication system 1 may be any of the devices shown in FIG. 1, for example, a core network device having any function among the terminal 10, the base station 20, and the CN30.

[0102] Each device in the communication system 1 includes a processor 11, a storage device 12, a communication device 13 that performs wired or wireless communication, an input device that accepts various input operations, and an input / output device 14 that outputs various information.

[0103] The processor 11 is, for example, a CPU (Central Processing Unit) and controls each device in the communication system 1. The processor 11 may execute various processes described in this embodiment by reading a program from the storage device 12 and executing it. Each device in the communication system 1 may be constituted by one or a plurality of processors 11. Also, each of these devices may be called a computer.

[0104] The storage device 12 is constituted by, for example, a memory, an HDD (Hard Disk Drive), and / or an SSD (Solid State Drive) or the like. The storage device 12 may store various information (for example, a program executed by the processor 11) necessary for the execution of the process by the processor 11.

[0105] The communication device 13 is a device that communicates via a wired and / or wireless network and may include, for example, a network card, a communication module, a chip, an antenna, etc. Also, the communication device 13 may include an amplifier, an RF (Radio Frequency) device that processes radio signals, and a BB (BaseBand) device that performs baseband signal processing.

[0106] The RF device generates a radio signal to be transmitted from the antenna A, for example, by performing D / A conversion, modulation, frequency conversion, power amplification, etc. on the digital baseband signal received from the BB device. Also, the RF device generates a digital baseband signal by performing frequency conversion, demodulation, A / D conversion, etc. on the radio signal received from the antenna and transmits it to the BB device. The BB device performs a process of converting a digital baseband signal into a packet and a process of converting a packet into a digital baseband signal.

[0107] The input / output device 14 includes, for example, an input device such as a keyboard, a touch panel, a mouse, and / or a microphone, and an output device such as a display and / or a speaker.

[0108] The hardware configuration described above is merely an example. Each device in the communication system 1 may omit some of the hardware described in FIG. 9, or may include hardware not described in FIG. 9. Also, the hardware shown in FIG. 9 may be constituted by one or a plurality of chips.

[0109] <Functional block configuration> (MB-SMF) FIG. 10 is a diagram showing an example of the functional block configuration of the core network device according to the present embodiment. In FIG. 10, the functional block configuration of the MB-SMF 34 is illustrated, but a core network device having functions other than the MB-SMF 34 may have a similar functional block configuration. The MB-SMF 34 includes a receiving unit 101, a transmitting unit 102, and a control unit 103. Also, the receiving unit 101 and the transmitting unit 102 are collectively referred to as a communication unit 110.

[0110] Note that all or part of the functions realized by the receiving unit 101 and the transmitting unit 102 can be realized using the communication device 13. Also, all or part of the functions realized by the receiving unit 101 and the transmitting unit 102 and the control unit 103 can be realized by the processor 11 executing a program stored in the storage device 12. Also, the program can be stored in a storage medium. The storage medium storing the program may be a non-transitory computer readable medium. The non-transitory storage medium is not particularly limited, but may be a storage medium such as a USB memory or a CD-ROM, for example.

[0111] The communication unit 110 transmits and receives various messages to and from other functions (NFs) within the terminal 10, the base station 20, or the CN 30. The receiving unit 101 receives various messages from other functions within the terminal 10, the base station 20, or the CN 30. The transmitting unit 102 transmits various messages to other functions within the terminal 10, the base station 20, or the CN 30.

[0112] The control unit 103 performs various controls related to the functions implemented by the MB-SMF 34. Also, when setting up an MBS session, the control unit 103 needs to confirm whether it is necessary to query the PCF 39 that controls the MBS policy about the MBS policy. Here, the PCF 39 is an example of a first core network device that controls the MBS policy. Also, the policy applied to the MBS session is an example of the MBS policy.

[0113] Also, the communication unit 110 may be configured to receive PCF usage information indicating that it is necessary to query the PCF 39 about the MBS policy when setting up an MBS session from the NEF / MBSF 36. Here, the NEF / MBSF 36 is an example of a third core network device. Also, the PCF usage information is an example of the first predetermined information.

[0114] The PCF usage information may be included in a message requesting the allocation of a TMGI transmitted from the NEF / MBSF 36. That is, the communication unit 110 may be configured to receive the PCF usage information included in a message requesting the allocation of a TMGI transmitted from the NEF / MBSF 36 (for example, step S131 in FIG. 5).

[0115] Also, the PCF usage information may be included in a message requesting the generation of an MBS session transmitted from the NEF / MBSF 36. That is, the communication unit 110 may be configured to receive the PCF usage information included in a message requesting the generation of an MBS session transmitted from the NEF / MBSF 36 (for example, step S191 in FIG. 6).

[0116] Also, when the control unit 103 determines that the message received by the communication unit 110 that requests the allocation of TMGI or the message that requests the generation of an MBS session contains PCF usage information, the control unit 103 may be configured to recognize that it is necessary to inquire about the MBS policy from the PCF 39. Also, when the control unit 103 determines that the message received by the communication unit 110 that requests the allocation of TMGI or the message that requests the generation of an MBS session does not contain PCF usage information, the control unit 103 may be configured to recognize that it is not necessary to inquire about the MBS policy from the PCF 39. (Step S131 in FIG. 5, Step S195 in FIG. 6).

[0117] Also, when the control unit 103 determines that the MB-SMF 34 itself does not have information regarding the MBS policy set therein, the control unit 103 may be configured to recognize that it is necessary to inquire about the MBS policy from the PCF 39. On the other hand, when the control unit 103 determines that the MB-SMF 34 itself has information regarding the MBS policy set therein, the control unit 103 may be configured to recognize that it is not necessary to inquire about the MBS policy from the PCF 39 (Step S192 in FIG. 7).

[0118] Also, when the control unit 103 determines that information indicating that it is necessary to execute dynamic policy control is set in the MB-SMF 34 itself, the control unit 103 may be configured to recognize that it is necessary to inquire about the MBS policy from the PCF 39. On the other hand, when the control unit 103 determines that information indicating that it is necessary to execute dynamic policy control is not set in the MB-SMF 34 itself, the control unit 103 may be configured to recognize that it is not necessary to inquire about the MBS policy from the PCF 39 (Step S192 in FIG. 7). Here, the information indicating that it is necessary to execute dynamic policy control is an example of the second predetermined information.

[0119] When the communication unit 110 needs to inquire about the MBS policy from the PCF 39 (when the control unit 103 recognizes that it is necessary to inquire about the MBS policy from the PCF 39 that controls the policy), it acquires specific information for identifying the PCF 39 from the NRF 42. Here, the NRF 42 is an example of a second core network device that detects functions existing within the core network. Also, information related to NF instances for one or more PCFs 39 (for example, NF profiles) is an example of specific information.

[0120] Also, the control unit 103 identifies the PCF 39 based on the acquired specific information. The control unit 103 identifying the PCF 39 based on the acquired specific information may mean that the control unit 103 detects and selects the PCF 39 based on the specific information.

[0121] The communication unit 110 transmits a message for inquiring about the MBS policy to the PCF 39 identified by the control unit 103.

[0122] (NEF / MBSF) FIG. 11 is a diagram showing an example of the functional block configuration of the core network device according to the present embodiment. In FIG. 11, the functional block configuration of the NEF / MBSF 36 is illustrated, but a core network device having functions other than the NEF / MBSF 36 may have a similar functional block configuration. The NEF / MBSF 36 includes a receiving unit 201, a transmitting unit 202, and a control unit 203. Also, the receiving unit 201 and the transmitting unit 202 are collectively referred to as a communication unit 210.

[0123] Note that all or part of the functions realized by the receiving unit 201 and the transmitting unit 202 can be realized using the communication device 13. Also, all or part of the functions realized by the receiving unit 201 and the transmitting unit 202, and the control unit 203 can be realized by the processor 11 executing a program stored in the storage device 12. Further, the program can be stored in a storage medium. The storage medium storing the program may be a non-transitory computer readable medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a USB memory or a CD-ROM.

[0124] The communication unit 210 transmits and receives various messages to and from other CNs 30. The receiving unit 201 receives various messages from other CNs 30. The transmitting unit 202 transmits various messages to other CNs 30.

[0125] Also, when the communication unit 210 receives information indicating that it is necessary to inquire about the MBS policy from the NRF 42 to the PCF 39 that controls the policy when setting up an MBS session, the communication unit 210 transmits a message requesting the allocation of a TMGI or a message requesting the generation of an MBS session, including PCF usage information, to the MB-SMF 34. Also, when the communication unit 210 receives information indicating that it is not necessary to inquire about the MBS policy from the NRF 42 to the PCF 39 that controls the policy when setting up an MBS session, the communication unit 210 transmits a message requesting the allocation of a TMGI or a message requesting the generation of an MBS session, not including PCF usage information, to the MB-SMF 34 (step S131 in FIG. 5, S191 in FIG. 6) The control unit 203 performs various controls regarding the functions realized by the NEF / MBSF 36.

[0126] <Summary> As described above, according to the communication system 1 according to the present embodiment, when the MB-SMF34 needs to inquire about the MBS policy from the PCF39, the MB-SMF34 identifies the PCF39 and obtains the MBS policy from the identified PCF39. Thereby, in multicast and / or broadcast communication, it becomes possible to appropriately perform policy control. Further, the MB-SMF34 transmits the PCF identification information of the identified PCF39 to the NEF / MBSF36. Thereby, since the NEF / MBSF36 can omit the process of inquiring the BSF40 about the PCF identification information, it becomes possible to reduce the consumption amount of network resources.

[0127] <Supplementary Note> In the above embodiment, the term "function" may be replaced with "device". "Inquiring about the MBS policy from the PCF39" may be replaced with "obtaining the MBS policy from the PCF39".

[0128] The various signals, information, and parameters in the above embodiment may be signaled at any layer. That is, the various signals, information, and parameters may be replaced with signals, information, and parameters of any layer such as an upper layer (for example, a Non-Access Stratum (NAS) layer, an RRC layer, a MAC layer, etc.) or a lower layer (for example, a physical layer). Further, the notification of predetermined information is not limited to being explicitly performed, and may be implicitly performed (for example, by not notifying information or using other information).

[0129] Also, the names of the various messages, signals, information, and parameters in the above embodiment are merely examples and may be replaced with other names.

[0130] The formats of the various information are not limited to the above embodiment, and may be appropriately changed such as bit representation (0 or 1), true / false value (Boolean: true or false), integer value, character, etc. Also, the singular and plural in the above embodiment may be changed to each other.

[0131] The embodiments described above are for facilitating the understanding of the present disclosure and are not for limiting and interpreting the present disclosure. The flowcharts, sequences, each element included in the embodiments, as well as their arrangements, indexes, conditions, etc. described in the embodiments are not limited to those exemplified and can be changed as appropriate. Also, at least a part of the configurations described in the above embodiments can be partially replaced or combined.

Description of Reference Numerals

[0132] 1... Communication system, 10... Terminal, 20... Base station, 30... CN, 31... AMF, 32... SMF, 33... UPF, 34... MB - SMF, 35... MB - UPF, 36... NEF / MBSF, 36a... NEF, 36b... MBSF, 37... AF, 38... MBSTF, 39... PCF, 40... BSF, 41... UDR, 42... NRF, 101... Receiver, 102... Transmitter, 103... Control unit, 201... Receiver, 202... Transmitter, 203... Control unit, 11... Processor, 12... Storage device, 13... Communication device, 14... Input / output device

Claims

1. A core network device for managing a multicast broadcast service (MBS) session, comprising: a control unit that, when setting up the MBS session, confirms whether or not it is necessary to inquire about a policy applied to the MBS session from a first core network device that controls the policy; a communication unit that acquires, when it is necessary to inquire about the policy from the first core network device, specific information for identifying the first core network device from a second core network device that detects functions present in a core network; The control unit identifies the first core network device based on the identification information; The communication unit transmits a message to the identified first core network device inquiring about a policy to be applied to the MBS session. A core network device having the above configuration.

2. The communication unit receives, from a third core network device, first predetermined information indicating that it is necessary to inquire of the first core network device about the policy when setting up the MBS session; the control unit recognizes that it is necessary to inquire about the policy of the first core network device when the first predetermined information is received from the third core network device; The core network device according to claim 1 .

3. The communication unit acquires the first predetermined information included in a Temporary Mobile Group Identifier (TMGI) assignment request message transmitted from the third core network device. The core network device according to claim 2 .

4. The communication unit acquires the first predetermined information included in a message requesting generation of an MBS session, the message being transmitted from the third core network device. The core network device according to claim 2 .

5. The control unit recognizes that it is necessary to inquire about the policy from the first core network device when information about the policy is not set in the core network device. A core network device according to any one of claims 1 to 4.

6. The control unit recognizes that it is necessary to inquire about the policy from the first core network device when second predetermined information indicating that dynamic policy control needs to be executed is set in the core network device. A core network device according to any one of claims 1 to 4.

7. A communication method performed by a core network device that manages a multicast broadcast service (MBS) session, comprising: determining whether or not a policy to be applied to the MBS session needs to be queried from a first core network device that controls the policy when the MBS session is established; When it is necessary to inquire about the policy from the first core network device, acquiring identification information for identifying the first core network device from a second core network device that detects functions present in a core network; identifying the first core network device based on the identification information; sending a message to the identified first core network device inquiring about a policy to be applied to the MBS session; A communication method including:

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