Core network device and communication method

Abstract

To provide a core network device and a communication method that can appropriately perform policy control, in multicast and / or broadcast communication.SOLUTION: Provided is a core network device for managing an MBS session includes: a control unit for confirming whether or not it is necessary to inquire a policy to a first core network device for controlling a policy applied to the MBS session when the MBS session is set; and a communication unit for acquiring specific information for specifying the first core network device from a second core network device for detecting functions existing in the core network when it is necessary to inquire the policy to the first core network device. The control unit specifies the first core network device on the basis of the specific information. The communication unit sends messages to inquire a policy applied to the MBS session to the specified first core network device.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The Third Generation Partnership Project (3GPP), an international standardization organization, has specified Release 15 of New Radio (NR), a fifth generation (5G) RAT, as the successor to Long Term Evolution (LTE), a 3.9th generation radio access technology (RAT), and LTE-Advanced, a fourth generation RAT (for example, Non-Patent Document 1).

[0003] In addition, Release 15 of the 5G Core Network (5GC), which is the fifth generation core network (CN), has also been specified 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 literature]

[0004] [Non-Patent Document 1] 3GPP TS 38.300 V15.2.0 (2018-06) [Non-Patent Document 2] 3GPP TS 23.501 V15.2.0 (2018-06) Summary of the Invention [Problem 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 desirable to be able to appropriately control policy in multicast and / or broadcast communication, just like in unicast communication.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a core network device and a communication method that enable appropriate policy control in multicast and / or broadcast communications. [Means for solving the problem]

[0008] A core network device according to one embodiment of the present disclosure is a core network device that manages a multicast broadcast service (MBS) session, and has a control unit that, when setting up the MBS session, confirms whether it is necessary to inquire of a first core network device that controls the policy about a 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, obtains identification information for identifying the first core network device from a second core network device that detects functions present in the core network, wherein the control unit identifies the first core network device based on the identification information, and the communication unit sends a message to the identified first core network device inquiring about the policy to be applied to the MBS session. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a core network device and a communication method that enable appropriate policy control in multicast and / or broadcast communication. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of an overview of a communication system according to an embodiment of the present invention. [Diagram 2] 11 is a diagram showing an example of a transmission mode of MBS data according to the embodiment. FIG. [Diagram 3] A figure showing an example of an MBS session setting procedure related to this embodiment. [Figure 4] A figure showing an example of an MBS session setting procedure related to this embodiment. [Diagram 5] FIG. 11 is a sequence diagram showing an example of a processing procedure 1-1 relating to detection and selection of a PCF. [Figure 6] FIG. 11 is a sequence diagram showing an example of a processing procedure 1-2 relating to detection and selection of a PCF. [Figure 7] FIG. 11 is a sequence diagram showing an example of a processing procedure 2 related to detection and selection of a PCF. [Figure 8] FIG. 11 is a sequence diagram showing an example of a processing procedure 2 related to detection and selection of a PCF. [Figure 9] FIG. 2 is a diagram illustrating an example of a hardware configuration of each device in the communication system according to the present embodiment. [Figure 10] FIG. 2 is a diagram illustrating an example of a functional block configuration of a core network device according to the present embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example of a functional block configuration of a core network device according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0012] Fig. 1 is a diagram showing an example of an overview of a 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 an MBS.

[0013] The terminal 10 is a specific terminal or device, such as 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 terminal (User Terminal), a radio apparatus, a subscriber terminal, an access terminal, etc. The terminal 10 may be of a mobile type or a fixed type.

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

[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 called a gNodeB (gNB), en-gNB, Radio Access Network (RAN), Access Network (AN), Next Generation-Radio Access Network (NG-RAN) node, low-power node, Central Unit (CU), Distributed Unit (DU), gNB-DU, Remote Radio Head (RRH), Integrated Access and Backhaul / Backhauling (IAB) node, or the like. The base station 20 is not limited to one node, and may be configured with multiple nodes (for example, a combination of a lower node such as a DU and an upper node such as a CU).

[0016] 1 may have any number equal to or greater than one. Of course, one or more terminals 10 may be connected to one base station 20.

[0017] The CN 30 is, for example, a 5GC, but is not limited thereto, and may be an EPC or a sixth-generation or later core network. The CN 30 includes various functions such as an Access and Mobility Management Function (AMF) 31, a Session Management Function (SMF) 32, a User Plane Function (UPF) 33, a Multicast Broadcast (MB)-SMF 34, a Multicast Broadcast (MB)-UPF 35, a Network Exposure Function (NEF) / Multicast Broadcast Service Function (MBSF) 36, an Application Function (AF) 37, a Multicast Broadcast Service Transport Function (MBSTF) 38, a PCF 39, a Binding Support Function (BSF) 40, a Unified Data Repository (UDR) 41, and a Network Repository Function (NRF) 42. These functions are collectively called a Network Function (NF). An identifiable instance of each function (i.e., the actual state of an NF actually operating in a physical or virtual device) may be called an NF instance.

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

[0019] The AMF 31 is a function that manages access and / or mobility of the terminal 10. The AMF 31 performs processes related to the C-plane (e.g., registration management, connection management, mobility management) and the like. The AMF 31 also performs processes related to the Non-access stratum (NAS) and transmits and / or receives NAS messages to and from the terminal 10.

[0020] The SMF 32 is a function for managing sessions, and controls, for example, the establishment, updating, and release of sessions.

[0021] The UPF 33 has a function of being a connection point to a data network (DN) (not shown), and performs, for example, packet routing, forwarding, etc. The UPF 33 transmits and receives data via a PDU session with the terminal 10. The UPF 33 is a first user plane device that performs processing related to the U-plane.

[0022] The MB-SMF 34 is a function for managing sessions for MBS (hereinafter referred to as "MBS sessions"), and for example, controls the establishment, update, release, etc. (including QoS control) of MBS sessions. An MBS session is also called a Multicast Broadcast (MB) session, etc. The MB-SMF 34 also sets the MB-UPF 35, which controls the flow of MBS data, based on a local policy held by the MB-SMF 34 or MBS policy rules provided by the PCF 39. The MB-SMF 34 also assigns and releases a Temporary Mobile Group Identity (TMGI).

[0023] In addition, the participation in the MBS session may be accepted by a NAS message (e.g., UL NAS MB Session Join Request) from the terminal 10 to the AMF 31, a request message (e.g., MB Session Request) from the AMF 31 to the MB-SMF 34, a response message (e.g., MB Session Response) from the MB-SMF 34 to the AMF 31 in response to the request message, or a NAS message (e.g., DL NAS MB Session Join Accept) from the AMF 31 to the terminal 10 in response to the response message. 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. The source specific IP multicast address may be composed of two addresses: an IP unicast address (a source address for identifying the source of the multicast service) and an IP multicast address (a destination address for identifying the multicast service).

[0025] The MB-UPF 35 is a function that controls the flow of MBS data from the MBSTF 38 or a DN (not shown). 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 performs the selection of the MB-SMF 34 that provides an MBS session, the realization of communication between the AF 37 and the MB-SMF 34, and / or the control of the MBSTF 38. 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 referred to as NEF / MBSF 36.

[0027] The AF37 requests a multicast service or a broadcast service from the 5GC by providing service information including a QoS request to the 5GC. The AF37 may be, for example, a function provided by a provider that provides content.

[0028] The MBSTF 38 has a general packet transmission function and acts as a media anchor for MBS data.

[0029] The PCF 39 performs QoS control (QoS handling) in the MBS session when dynamic policy and charging control (dynamic PCC) is necessary. The PCF 39 also provides policy information (hereinafter referred to as "MBS policy") applied to the MBS session to the MB-SMF 34. The dynamic PCC means that the policy control and charging control are not static (fixed) but can be flexibly changed according to the network state and / or the service provision contents. The dynamic PCC may be called "dynamic policy control". The PCF 39 may obtain the MBS policy from the UDR 41 existing in the same PLMN (Public Land Mobile Network) as the PCF 39. Among the PCFs 39, the PCF 39 that controls the policy of the MBS session may be called an MB (Multicast Broadcast)-PCF.

[0030] The BSF 40 stores internal information (such as a user identifier, a Data Network Name (DNN), a UE address, a Single-Network Slice Selection Assistance Information (S-NSSAI), and a selected PCF address) related to a PDU session (including an MBS session). The PCF 39 accesses the BSF 40 and performs registration, update, deletion, and the like of information stored in the BSF 40.

[0031] The UDR 41 provides the PCF 39 with a function for storing and retrieving policy data.

[0032] The NRF 42 detects NFs present in the core network. In addition, when the NRF 42 receives an NF detection request from an NF instance, the NRF 42 detects one or more NF instances that match the detection request, and provides information related to the detected one or more NF instances to the NF instance that transmitted the detection request. The information related to the NF instance may be referred to as an "NF profile" or may be referred to as "information for identifying an NF." The NF profile includes multiple pieces of information (e.g., parameters) related to an NF instance, such as an NF instance ID, an NF type, a network slice related ID (S-NSSAI, NSI ID (Network Slice Instance Identifier), etc.), an FQDN (Fully Qualified Domain Name) or IP address of an NF, NF capacity information, NF priority information, location information of an NF instance, TAI (Tracking Area Identity), NF load information, etc. The content of the information included in the NF profile differs depending on the NF.

[0033] Here, "Discovery" of an NF means that an NF instance within CN30 discovers other NF instances to be communicated 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, "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 the NF instance may be set in advance as local information within the NF, or may be determined based on the operator's policy or the like. There are a large number of NF instances within 5GC. By using the mechanism for performing NF discovery and selection, the NF can identify the NF instance to be communicated with from among a large number of NF instances.

[0034] <Method for Transmitting MBS Data> In the communication system 1 as described above, the 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 the 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 by the CN 30 is transmitted to each terminal 10 via a PDU session for each terminal 10 (for example, a single unicast PDU session with each terminal 10). The individual mode is also called 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, MBS data (a single copy of MBS data) received by the CN 30 is transmitted to the base station 20 via shared transport with the base station 20, and is then transmitted from the base station 20 to the terminal 10 under its control by point-to-point (PTP) or point-to-multi-point (PTM). The shared mode is also called the second transmission mode, Shared MBS Traffic delivery, 5GC Shared MBS traffic delivery method, Shared-mode, etc. The terminal 10 in the shared mode can receive MBS data when the base station 20 forming the serving cell supports MBS.

[0037] 2 is a diagram showing an example of a transmission mode of MBS data according to this embodiment. As shown in FIG. 2, MBS data from a DN (not shown) is received by the MB-UPF 35 in the CN 30.

[0038] In the individual mode, the MB-UPF35 transfers the received MBS data to the UPF33 via the N9 tunnel. Note that the N9 tunnel is a tunnel of the N9 interface. The UPF33 replicates the MBS data received from the MB-UPF35 and transmits it to each terminal 10 via the PDU session 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, the MB-UPF35 transmits the received MBS data to the base station 20 via the shared transport. The shared transport is a shared tunnel within the CN30 and is also called a shared downlink CN tunnel, N3 tunnel, etc. The base station 20 transmits the MBS data received from the 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 the 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> Figures 3 and 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 Figure 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 assign the TMGI in advance before configuring the MBS session. That is, the processing procedures of steps S100 to S160 correspond to the procedure for assigning 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 / MBSF 36 checks (authorizes) whether the AF 37 has the authority to execute the processing procedure of step S100. If the AF 37 has the authority, the process proceeds to the processing procedure of step S120.

[0046] In step S120, the NEF / MBSF 36 queries the NRF 42 or detects and selects the MB-SMF 34 based on its own local configuration.

[0047] For example, the NEF / MBSF 36 obtains information (e.g., a list of MB-SMF profiles) from the NRF 42 regarding candidate MB-SMFs 34 capable of performing TMGI allocation, and selects one MB-SMF 34 to which to request TMGI allocation based on the obtained information.

[0048] In step S130, the NEF / MBSF 36 transmits a message requesting allocation of a TMGI (eg, a TMGI allocation request) to one selected MB-SMF 34.

[0049] In step S140, the MB-SMF 34 allocates a TMGI, and transmits the allocated TMGI to the NEF / MBSF 36 in a TMGI allocation response message.

[0050] In step S150, the NEF / MBSF 36 transmits the TMGI allocated by the MB-SMF 34 to the AF 37 by including the TMGI in a TMGI allocation response message.

[0051] In step S160, the AF 37 performs a service announcement to the terminal 10 (not shown). For example, the AF 37 notifies the terminal 10 of the MBS session ID (here, the assigned TMGI) and other information (MBS service area, session description information, etc.).

[0052] In step S170, the AF 37 transmits an MBS session request message (e.g., MBS Session Request or Multicast Session Request) including information related to the MBS session (MBS session ID, service type (e.g., either broadcast service or multicast service), MBS information, etc.) to the NEF / MBSF 36. Note that if TMGI is assigned as the MBS session ID by the processing procedures of steps S100 to S160, the MBS session request includes TMGI. The MBS information may include MBS service area information, start time and end time of the MBS, etc. The NEF / MBSF 36 checks (Authorization) whether or not the AF 37 has the authority to execute the processing procedure of step S170, and if the AF 37 has the authority, proceeds to the processing procedure of step S180.

[0053] In step S180, the NEF / MBSF 36 queries the NRF 42 or detects and selects the MB-SMF 34 based on the settings of the MB-SMF 34 itself. If the TMGI has been assigned in the processing procedure of step S130, the NEF / MBSF 36 may select the MB-SMF 34 that has assigned the TMGI.

[0054] In step S190, the NEF / MBSF 36 transmits a message (for example, Nmbsmf_MBSSession_Create Request) requesting the creation of an MBS session to the selected MB-SMF 34. The message includes an MBS session ID, a TMGI allocation instruction, a service type, the MBS service area information notified by the AF 37 in step S170, and the like.

[0055] In step S200, the MB-SMF 34 assigns a TMGI if the MBS session ID is a source-specific IP multicast address in step S190. The MB-SMF 34 may also update the NF profile of the MB-SMF 34 stored in the NRF 42 using the MBS session ID.

[0056] In step S210, the MB-SMF 34 sends an MBS policy association request message including the MBS session ID to the PCF 39.

[0057] In step S220, the PCF 39 sends a message (e.g., Management register) to register that the PCF 39 handles the multicast session to the BSF 40. The message includes the MBS session ID and the PCF identification information of the PCF 39 itself (e.g., the NF instance ID, PCF ID, FQDN, and / or IP address of the PCF 39, etc.).

[0058] In step S230, the PCF 39 accesses the UDR 41 and obtains a preconfigured MBS policy associated with the MBS session ID.

[0059] In step S240, the PCF 39 transmits an MBS policy assignment response message (e.g., MBS Policy Association Response) including the MBS policy associated with the MBS session ID acquired in step S230 to the MB-SMF 34. The MBS policy may include, for example, information on the QoS applied to the MBS session, information on the priority of the MBS service, information on the area in which the MBS session is provided, information on the date and time or time period in which the MBS session is provided, and / or information on the network slice in which the MBS session is provided.

[0060] In step S250, MB-SMF 34 selects MB-UPF 35 and transmits a message (Session Request) to the selected MB-UPF 35 requesting reservation of resources for transmitting a user plane (i.e., MBS data to be transmitted to terminal 10) to the selected MB-UPF 35. At this time, MB-SMF 34 may notify MB-UPF 35 of the MBS policy to be applied when transmitting MBS data to terminal 10 by transmitting the message to MB-UPF 35 including an MBS policy.

[0061] In step S260, the MB-UPF 35 sends a session response message (eg, Session Response) to the MB-SMF 34.

[0062] In step S270, the MB-SMF 34 transmits an MBS session creation response message (for example, Nmbsmf_MBSSession_Create Response) to the NEF / MBSF 36. The message includes the MBS session ID and information indicating whether the allocation of resources for transmitting MBS data has succeeded or failed.

[0063] In step S280, the NEF / MBSF 36 may send a discovery request message (e.g., a Man Discovery Request) including the MBS session ID to the BSF 40 to discover the PCF 39 that processes the MBS session having the MBS session ID notified in step S270.

[0064] In step S290, the BSF 40 transmits the PCF identification information of the PCF 39 associated with the notified MBS session ID to the NEF / MBSF 36. The PCF identification information transmitted to the NEF / MBSF 36 is the PCF identification information registered in the BSF 40 in the processing procedure of step S220 in FIG.

[0065] In step S300, 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 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, when the MB-SMF34 updates the MBS policy if 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 the MBS session ID) to the AF37.

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

[0072] <Processing procedure regarding detection and selection of PCF> Next, a specific process procedure for detecting and selecting the PCF 39 in the MBS session setup procedure will be described. In the following description, the same process procedures as those in the description of Fig. 3 and Fig. 4 are given the same reference numerals, and the description thereof may be omitted.

[0073] (Processing procedure 1-1) In process step 1-1, detection and selection of the PCF 39 are performed in the process step of allocating the TMGI.

[0074] FIG. 5 is a sequence diagram showing an example of a process procedure 1-1 relating to detection and selection of a PCF.

[0075] In step S120, the NEF / MBSF 36 queries the NRF 42 or detects and selects the MB-SMF 34 based on its own local configuration.

[0076] In step S121, the NRF 42, having received a query from the NEF / MBSF 36, accesses the UDR 41 and checks whether or not it is necessary to query the PCF 39 about the MBS policy when setting up an MBS session to which a TMGI is assigned. The NRF 42 notifies the NEF / MBSF 36 of the confirmation result (i.e., information indicating whether or not it is necessary to query the PCF 39 about the MBS policy).

[0077] In step S131, the NEF / MBSF 36 transmits a message requesting allocation of a TMGI (e.g., a TMGI allocation request) to one selected MB-SMF 34. When a confirmation result that it is necessary to inquire of the PCF 39 about the MBS policy is received from the NRF 42, the NEF / MBSF 36 includes information indicating that it is necessary to inquire of the PCF 39 about the MBS policy (hereinafter referred to as "PCF usage information" or "PCF information") in the message. On the other hand, when a confirmation result that it is not necessary to inquire of the PCF 39 about the MBS policy is received from the NRF 42, the NEF / MBSF 36 transmits the message without including the "PCF usage information".

[0078] In step S132, if the message requesting allocation of a TMGI includes PCF usage information, MB-SMF 34 recognizes that it is necessary to inquire about the MBS policy of PCF 39. If the message requesting allocation of a TMGI does not include PCF usage information, MB-SMF 34 recognizes that it is not necessary to inquire about the MBS policy of PCF 39.

[0079] When it is recognized that it is necessary to inquire of the PCF 39 about the MBS policy, the MB-SMF 34 detects and selects the PCF 39 by inquiring of the NRF 42. For example, the MB-SMF 34 may receive from the NRF 42 NF profiles (e.g., a list of NF profiles of candidate PCFs 39) for one or more PCFs 39 detected by the NRF 42, and select one PCF 39 that performs policy control of the MBS session to be set based on the received one or more NF profiles and information locally configured in the MB-SMF 34, or based on the received one or more NF profiles and an operator's policy. The locally configured information or the operator's policy may define the NF profile used to select the PCF 39 and the method or criteria for selecting the PCF 39 using the NF profile.

[0080] For example, the NF profile for the PCF 39 may include information indicating the AF 37 associated with the PCF 39, and the MB-SMF 34 may select the PCF 39 associated with the AF 37 that has requested the establishment of an MBS session from among multiple PCFs 39 detected by the NRF 42. In other words, the locally configured information or the operator's policy may define a method of "selecting the PCF 39 associated with the AF 37 that has requested the establishment of an MBS session."

[0081] Also, for example, the NF profile for the PCF 39 may include information indicating the service type (broadcast service or multicast service) of the MBS associated with the PCF 39, and the MB-SMF 34 may select the PCF 39 associated with the service type requested in the MBS session to be set. In other words, the locally set information or the operator's policy may define a method of "selecting the PCF 39 associated with the service type requested in the MBS session to be set."

[0082] Once the selection of the PCF 39 is completed, the MB-SMF 34 stores the PCF identification information of the selected PCF 39 (eg, the NF instance ID, PCF ID, FQDN and / or IP address of the PCF 39, etc.).

[0083] In step S211, the MB-SMF 34 transmits an MBS policy association request message including the MBS session ID to the PCF 39 selected in the processing procedure of step S131.

[0084] (Processing procedure 1-2) In the process step 1-2, the PCF 39 is detected and selected in the process step for setting up an MBS session.

[0085] FIG. 6 is a sequence diagram showing an example of a process procedure 1-2 relating to detection and selection of a PCF.

[0086] In step S180, the NEF / MBSF 36 queries the NRF 42 or detects and selects the MB-SMF 34 based on its own configuration.

[0087] In step S181, the NRF 42, having received a query from the NEF / MBSF 36, accesses the UDR 41 and checks whether or not it is necessary to query the PCF 39 about the MBS policy when setting up an MBS session to allocate a TMGI. The NRF 42 notifies the NEF / MBSF 36 of the confirmation result (i.e., information indicating whether or not it is necessary to query the PCF 39 about the MBS policy).

[0088] In step S191, the NEF / MBSF 36 transmits a message (e.g., Nmbsmf_MBSSession_Create Request) requesting the creation of an MBS session to the selected MB-SMF 34. The message includes an MBS session ID, a TMGI allocation instruction, a service type, MBS service area information notified from the AF 37 in step S170, and the like. If the NEF / MBSF 36 receives a confirmation result from the NRF 42 indicating that it is necessary to inquire of the PCF 39 about the MBS policy, the NEF / MBSF 36 includes information indicating that it is necessary to inquire of the PCF 39 about the MBS policy (hereinafter referred to as "PCF usage information" or "PCF information") in the message. On the other hand, if the NEF / MBSF 36 receives a confirmation result from the NRF 42 indicating that it is not necessary to inquire of the PCF 39 about the MBS policy, the NEF / MBSF 36 transmits the message without including the "PCF usage information".

[0089] In step S195, if the message requesting the generation of an MBS session includes PCF usage information, the MB-SMF 34 recognizes that it is necessary to inquire of the PCF 39 about the MBS policy. If the message requesting the generation of an MBS session does not include PCF usage information, the MB-SMF 34 recognizes that it is not necessary to inquire of the PCF 39 about the MBS policy. If it is recognized that it is necessary to inquire of the PCF 39 about the MBS policy, the MB-SMF 34 detects and selects the PCF 39 by inquiring of the NRF 42. The method of detecting and selecting the PCF 39 is the same as the processing procedure of step S132 in Fig. 5, so a description thereof will be omitted. When the selection of the PCF 39 is completed, the MB-SMF 34 holds the PCF identification information of the selected PCF 39 (for example, the NF instance ID, PCF ID, FQDN and / or IP address of the PCF 39, etc.). Furthermore, the MB-SMF 34 may store the PCF identification information of the selected PCF 39 in, for example, the MBS Session context.

[0090] The processing procedure in step S211 is the same as that in FIG. 5, and therefore a description thereof will be omitted.

[0091] (Processing Step 2) In process step 2, the PCF 39 is detected and selected in the process step of setting up an MBS session. However, unlike process steps 1-1 and 1-2, the MB-SMF 34, not the NRF 42, checks whether it is necessary to inquire about the MBS policy from the PCF 39.

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

[0093] In step S192, MB-SMF 34 checks whether or not it is necessary to inquire about the MBS policy to PCF 39 when setting up an MBS session. For example, MB-SMF 34 may be configured to recognize that, when information about the MBS policy is set in MB-SMF 34 itself, it is not necessary to inquire about the MBS policy to PCF 39. Also, MB-SMF 34 may be configured to recognize that, when information about the MBS policy is not set in MB-SMF 34, it is necessary to inquire about the MBS policy to PCF 39.

[0094] Also, for example, when information indicating that execution of dynamic PCC is required is set in MB-SMF 34, MB-SMF 34 may recognize that it is necessary to inquire about the MBS policy of PCF 39. Also, when information indicating that execution of dynamic PCC is required is not set in MB-SMF 34, MB-SMF 34 may recognize that it is not necessary to inquire about the MBS policy of PCF 39.

[0095] The processing procedures of steps S195 and S211 are the same as those in FIG. 5 and FIG. 6, and therefore the description thereof will be omitted.

[0096] In step S271, the MB-SMF 34 transmits an MBS session creation response message (for example, Nmbsmf_MBSSession_Create Response) to the NEF / MBSF 36. The message includes an MBS session ID, information indicating whether allocation of resources for transmitting MBS data has succeeded or failed, and PCF identification information of the PCF 39 selected in the processing procedure of step S195. The PCF identification information may be, for example, an NF instance ID, PCF ID, FQDN, and / or IP address of the PCF 39.

[0097] Since the NEF / MBSF 36 has received the PCF identification information of the PCF 39 in the process of step S271, the process of steps S280 and 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 there is no need 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, the NEF / MBSF36 may detect and select the PCF39 by inquiring about the NRF42. Also, the NEF / MBSF36 may include information regarding the selected PCF39 instead of (and / or in addition to) the PCF usage information in a message requesting the allocation of a TMGI 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] The devices in the communication system 1 include a processor 11, a storage device 12, a communication device 13 that performs wired or wireless communication, and 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 the present embodiment by reading and executing a program from the storage device 12. Each device in the communication system 1 may be configured with one or more processors 11. Furthermore, each of the devices may be called a computer.

[0104] The storage device 12 is configured with, for example, storage such as a memory, a hard disk drive (HDD) and / or a solid state drive (SSD), etc. The storage device 12 may store various information necessary for the processor 11 to execute processing (for example, a program executed by the processor 11, etc.).

[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. The communication device 13 may also include an amplifier, an RF (Radio Frequency) device that performs processing related to wireless signals, and a BB (BaseBand) device that performs baseband signal processing.

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

[0107] The input / output device 14 includes, for example, input devices such as a keyboard, a touch panel, a mouse, and / or a microphone, and output devices 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 shown in Fig. 9, or may include hardware not shown in Fig. 9. Furthermore, the hardware shown in Fig. 9 may be configured by one or more chips.

[0109] <Function block configuration> (MB-SMF) Fig. 10 is a diagram showing an example of a functional block configuration of a core network device according to this embodiment. Fig. 10 illustrates the functional block configuration of MB-SMF34, but a core network device having a function other than MB-SMF34 may have a similar functional block configuration. MB-SMF34 includes a receiving unit 101, a transmitting unit 102, and a control unit 103. The receiving unit 101 and the transmitting unit 102 are collectively referred to as a communication unit 110.

[0110] All or part of the functions realized by the receiving unit 101 and the transmitting unit 102 can be realized by using the communication device 13. 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. 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.

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

[0112] The control unit 103 performs various controls related to the functions realized by the MB-SMF 34. Furthermore, when setting up an MBS session, the control unit 103 checks whether or not it is necessary to inquire about an MBS policy from the PCF 39 that controls the MBS policy. Note that the PCF 39 is an example of a first core network device that controls the MBS policy. Furthermore, the policy applied to the MBS session is an example of an MBS policy.

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

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

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

[0116] Furthermore, when the message requesting allocation of a TMGI or the message requesting generation of an MBS session received by the communication unit 110 includes PCF usage information, the control unit 103 may recognize that it is necessary to inquire of the PCF 39 about the MBS policy. Furthermore, when the message requesting allocation of a TMGI or the message requesting generation of an MBS session received by the communication unit 110 does not include PCF usage information, the control unit 103 may recognize that it is not necessary to inquire of the PCF 39 about the MBS policy (step S131 in FIG. 5, step S195 in FIG. 6).

[0117] Furthermore, when information about the MBS policy is not 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 of the PCF 39. On the other hand, when information about the MBS policy is 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 of the PCF 39 (step S192 in FIG. 7).

[0118] Furthermore, when information indicating that dynamic policy control needs to be executed is set in MB-SMF34 itself, the control unit 103 may be configured to recognize that it is necessary to inquire about the MBS policy of the PCF 39. On the other hand, when information indicating that dynamic policy control needs to be executed is not set in MB-SMF34 itself, the control unit 103 may be configured to recognize that it is not necessary to inquire about the MBS policy of the PCF 39 (step S192 in FIG. 7). Here, the information indicating that dynamic policy control needs to be executed is an example of the second predetermined information.

[0119] When it is necessary 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), the communication unit 110 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 present in the core network. Also, information related to NF instances (e.g., NF profiles) for one or more PCFs 39 is an example of specific information.

[0120] Furthermore, the control unit 103 identifies the PCF 39 based on the acquired identification information. Identifying the PCF 39 based on the acquired identification information by the control unit 103 may mean that the control unit 103 detects and selects the PCF 39 based on the identification information.

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

[0122] (NEF / MBSF) Fig. 11 is a diagram showing an example of a functional block configuration of a core network device according to this embodiment. Fig. 11 illustrates the functional block configuration of the NEF / MBSF 36, but a core network device having a function 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. The receiving unit 201 and the transmitting unit 202 are collectively referred to as a communication unit 210.

[0123] All or part of the functions realized by the receiving unit 201 and the transmitting unit 202 can be realized by using the communication device 13. 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. 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] Furthermore, when the communication unit 210 receives from the NRF 42 information indicating that it is necessary to inquire about an MBS policy from the PCF 39 that controls the policy when setting up an MBS session, the communication unit 210 transmits a message requesting allocation of a TMGI including PCF usage information or a message requesting generation of an MBS session to the MB-SMF 34. Furthermore, when the communication unit 210 receives from the NRF 42 information indicating that it is not necessary to inquire about an MBS policy from the PCF 39 that controls the policy when setting up an MBS session, the communication unit 210 transmits to the MB-SMF 34 a message requesting allocation of a TMGI or a message requesting generation of an MBS session that does not include PCF usage information (step S131 in FIG. 5, S191 in FIG. 6). The control unit 203 performs various controls related to the functions realized by the NEF / MBSF 36 .

[0126] <Summary> As described above, in the communication system 1 according to this embodiment, when it is necessary for the MB-SMF 34 to inquire about an MBS policy from the PCF 39, the MB-SMF 34 identifies the PCF 39 and acquires the MBS policy from the identified PCF 39. This makes it possible to appropriately perform policy control in multicast and / or broadcast communication. Furthermore, the MB-SMF 34 transmits the PCF identification information of the identified PCF 39 to the NEF / MBSF 36. This allows the NEF / MBSF 36 to omit the process of inquiring about PCF identification information from the BSF 40, thereby making it possible to reduce the consumption of network resources.

[0127] <Additional information> The term “function” in the above embodiment may be replaced with “device.” “Inquiring the PCF 39 about the MBS policy” may be replaced with “obtaining the MBS policy from the PCF 39.”

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

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

[0130] The format of the various information is not limited to the above embodiment, and may be changed as appropriate to bit representation (0 or 1), boolean (true or false), integer value, character, etc. Also, the singular and plural in the above embodiment may be changed interchangeably.

[0131] The above-described embodiments are intended to facilitate understanding of the present disclosure, and are not intended to limit the present disclosure. The flowcharts, sequences, elements included in the embodiments, and their arrangements, indexes, conditions, etc. described in the embodiments are not limited to those exemplified, and can be changed as appropriate. In addition, at least some of the configurations described in the above embodiments can be partially replaced or combined. [Explanation of symbols]

[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...receiving unit, 102...transmitting unit, 103...control unit, 201...receiving unit, 202...transmitting unit, 203...control unit, 11...processor, 12...storage device, 13...communication device, 14...input / output device

Claims

1. A core network system comprising: a core network function that manages a multicast broadcast service (MBS) session; and a third core network function that determines to inquire of a first core network function based on configuration information related to a policy applied to the MBS session, The core network function a control unit that checks whether or not it is necessary to inquire about the policy from the first core network function that controls the policy when setting up the MBS session; A communication unit that receives, from the third core network function, first predetermined information indicating that it is necessary to inquire about the policy from the first core network function when setting up the MBS session; having A core network system, wherein the third core network function selects the first core network function by querying a second core network function that detects functions present in the core network.

2. The third core network function detects candidates for the first core network function when selecting the first core network function by querying the second core network function. The core network system 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 function.

3. A core network system according to claim 1 or 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 function.

3. A core network system according to claim 1 or 2.

5. The control unit recognizes that it is necessary to inquire about the policy from the first core network function when information about the policy is not set in the core network function. A core network system 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 function when second predetermined information indicating that dynamic policy control needs to be executed is set in the core network function. A core network system according to any one of claims 1 to 4.

7. A communication method executed by a core network function that manages a multicast broadcast service (MBS) session and a third core network function that determines to inquire a first core network function based on configuration information related to a policy applied to the MBS session, comprising: The core network function checking whether said policy needs to be queried from said first core network function controlling said policy when setting up said MBS session; receiving, from the third core network function, first predetermined information indicating that the policy needs to be queried from the first core network function when setting up the MBS session; Run A method of communication, wherein the third core network function selects the first core network function by querying a second core network function that performs detection of functions present in a core network.

8. The third core network function detects candidates for the first core network function when selecting the first core network function by querying the second core network function. The communication method according to claim 7.

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