Network device, user terminal, communication method and computer program

Abstract

To appropriately configure a multi-access session.SOLUTION: In a mobile communication system having a core network connected to a plurality of radio access networks, a network device equipped in the core network includes a measurement information acquisition unit that acquires measurement information indicating communication quality of each of the plurality of radio access networks, and a multi-access session configuration determination unit that determines, based on the measurement information, a radio access network to be used for multi-access session to be established between a user terminal and the core network from among the plurality of radio access networks.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a network device, a user terminal, a communication method, and a computer program. [Background technology]

[0002] Conventionally, a fifth generation mobile communication system (5G system) standardized by "3GPP (registered trademark) (3rd Generation Partnership Project)" is known (for example, see Non-Patent Documents 1 and 2). FIG. 9 is a diagram showing a schematic architecture of a 5G system. In FIG. 9, the 5G system is composed of UE (User Equipment), RAN (Radio Access Network), UPF (User Plane Function) of CN (Core Network), and various NFs (Network Functions) of the control plane (Control plane: C-plane) of the CN. Examples of NFs of the C-plane of the CN include AMF (Access and Mobility Management Function), SMF (Session Management Function), and UDM (Unified Data Management).

[0003] Here, a logical communication path that the UE establishes with the CN (UPF) to use a mobile communication service is called a "session". A session that the UE establishes with the CN (UPF) using multiple wireless paths is called a "multi-access session". Non-Patent Documents 1 and 2 specify a "Multi-access PDU Session (hereinafter, referred to as an "MA PDU Session")" as an example of a multi-access session. FIG. 10 is a diagram showing a configuration example of an "MA PDU Session". As shown in FIG. 10, the UE establishes an "MA PDU Session" with the CN (UPF) using a wireless path via a RAN, which is "3gpp access", and a wireless path via a wireless LAN (Local Area Network) such as "Wi-Fi (registered trademark)", which is "non-3gpp access". "3gpp access" is an access network specified by 3GPP. "Non-3gpp access" is an access network other than "3gpp access". The UE uses the "MA PDU Session" to send and receive data between DN (Data Network), such as the Internet, outside the 5GC (CN of the 5G system). By using the "MA PDU Session", the UE can improve communication quality by expanding the communication band, reducing communication delays, and ensuring redundancy of the communication path.

[0004] In addition, Non-Patent Documents 1 and 2 specify a steering mode as a policy indicating how to transmit traffic related to the UE when a "MA PDU Session" is established. The steering mode is notified from the CN to the UE when a "MA PDU Session" is established. The steering modes (1)-(5) specified in Non-Patent Documents 1 and 2 are shown below.

[0005] (1) "Active-Standby" In "Active-Standby", traffic is basically transmitted to the "Active" access network, and if the "Active" access network becomes unavailable, it switches to the "Standby" access network. Then, when the "Active" access network becomes available again, it switches back to the "Active" access network.

[0006] (2) "Smallest Delay" "Smallest Delay" transmits traffic to the access network with the smallest RTT (Round Trip Time). UE and UPF can measure RTT of "3gpp access" and "non-3gpp access". If one access network becomes unavailable, all traffic will be transmitted to the other available access network. "Smallest Delay" is only applicable to "non-GBR SDF".

[0007] (3) "Load-Balancing" "Load-Balancing" is a mode used when distributing traffic to two sessions. Percentage information is set to indicate the percentage to be transmitted for each session. If one access network becomes unavailable, the other access network operates as if its percentage was set to 100%. "Load-Balancing" is only applicable to "non-GBR" traffic.

[0008] (4) "Priority-based" "Priority-based" is a mode used when distributing traffic to two sessions. All traffic is transmitted through the higher priority access network until the higher priority access network is determined to be "congested". In the event of congestion, traffic is also transmitted through the lower priority access network. The determination of congestion depends on the UE and UPF implementation. If one access network becomes unavailable, all traffic is transmitted through the other access network. "Priority-based" is only applicable to "non-GBR" traffic.

[0009] (5) "Redundant" When both access networks are available, traffic is transmitted redundantly through both access networks. "Primary access" information may be provided to the UE and UPF by the "ATSSS rule" and "N4 rule". "Primary access" may be "3gpp access" or "non-3gpp access". When "Primary access" information is provided, the UE and UPF transmit all traffic through "Primary access" and transmit redundant traffic through other access networks. In redundancy, how much data the UE and UPF duplicate depends on the implementation. When "Primary Access" information is not provided, the UE and UPF always duplicate all data and transmit it through both access networks.

[0010] Also, a configuration example of DC (Dual Connectivity) is shown in Fig. 11. DC is a technology that realizes a broadband by simultaneously using two sets (master and secondary) of RU (Radio Unit) and DU (Distributed Unit) of a UE to transmit user plane data between the UE and a UPF via a CU (Central Unit) (for example, see Non-Patent Document 3). [Prior art documents] [Non-patent literature]

[0011] [Non-Patent Document 1] 3GPP, TS 23.501, V18.2.0, 2023-06 [Non-Patent Document 2] 3GPP, TS 23.502, V18.2.0, 2023-06 [Non-Patent Document 3] 3GPP, TS 36.300, V17.0.0, 2022-03 Summary of the Invention [Problem to be solved by the invention]

[0012] In the next generation B5G (Beyond 5G) system after the 5G system and the sixth generation mobile communication system (6G system), multipath communication can be utilized as a means for achieving service requirements such as ultra-high capacity (100 Gbps class) and ultra-low latency (1 ms or less) for one user. However, the "MA PDU Session" described in Non-Patent Documents 1 and 2 as a multi-access session for realizing multipath communication is limited to a combination of "one 3gpp access (e.g., 5G base station)" and "one non-3gpp access (e.g., wireless LAN)", and therefore the service area of ​​multipath communication in which a UE can realize ultra-high capacity and ultra-low latency communication is small.

[0013] Therefore, if a multi-access session can be established as shown in Figure 12 using two arbitrarily selected "3gpp access" without limiting the PLMN (Public Land Mobile Network) (i.e., without limiting the communication carrier that manages the base station to which the UE is connected), the service area of ​​multipath communication will be significantly expanded, allowing many users to enjoy the benefits of multipath communication, such as ultra-high capacity communication and ultra-low latency.

[0014] In the conventional multi-access session establishment procedure, the SMF recognizes the access networks available for the multi-access session by checking the network registration information indicating the access network in which the UE is registered, and executes the session establishment process based on the recognition result. However, when the UE is registered in two "3gpp access" and one "non-3gpp access", there is a problem that it is not possible to determine an appropriate multi-access session configuration.

[0015] In addition, since the conventional DC is implemented by closed control in the RAN domain, it is implemented regardless of the configuration of the multi-access session established between the UE and the CN (UPF). This causes the following problems.

[0016] Fig. 13 shows an example of the configuration of a multi-access session. The multi-access session shown in Fig. 13 is composed of a first session SesA and a second session SesB. The first session SesA transmits data between the UE and the UPF by DC using a first wireless path dcA_1 "RU1-DU1-CU1" and a second wireless path dcA_2 "RU2-DU2-CU2-CU1". The second session SesB has only one wireless path "RU2-DU2-CU2".

[0017] In the configuration of the multi-access session in Fig. 13, if a multi-access session is used in the steering mode "Redundant" and DC is used, both the original data and the duplicated data may be transmitted over the wireless path "RU2-DU2-CU2". If both the original data and the duplicated data are transmitted over the wireless path "RU2-DU2-CU2", the traffic redundancy that is the purpose of the steering mode "Redundant" is not sufficiently achieved.

[0018] In addition, in the multi-access session configuration of Figure 13, if DC is used when a multi-access session is used in the steering mode "Load-Balancing", traffic may not be distributed to each session SesA, SesB in the desired ratio.

[0019] As described above, there are various problems associated with conventional multi-access sessions.

[0020] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to appropriately configure a multi-access session. [Means for solving the problem]

[0021] One aspect of the present invention is a network device provided in a core network in a mobile communications system having a core network connected to a plurality of radio access networks, the network device comprising: a measurement information acquisition unit that acquires measurement information indicating communication quality of each of the plurality of radio access networks; and a multi-access session configuration determination unit that determines, based on the measurement information, a radio access network from the plurality of radio access networks to be used for a multi-access session established by a user terminal between the core network and the plurality of radio access networks.

[0022] One aspect of the present invention is a network device provided in a core network in a mobile communications system including a core network connected to a plurality of radio access networks, the network device comprising: a multi-access session priority information storage unit that stores multi-access session priority information indicating a priority of a radio access network to be used for a multi-access session established by a user terminal between the core network; and a multi-access session configuration determination unit that determines a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information.

[0023] One aspect of the present invention is a network device as described above, further comprising a multi-access session configuration identification unit that identifies a configuration of a multi-access session to be established between the user terminal and the core network based on multi-access session configuration capability information indicating which combination of radio access networks among the plurality of radio access networks the user terminal has the capability of establishing a multi-access session with, and NW registration information indicating which radio access network among the plurality of radio access networks in which the user terminal is registered, and the multi-access session configuration determination unit determines a radio access network for the identification result of the multi-access session configuration. One aspect of the present invention is a network device in which, in the above-mentioned network device, the multi-access session configuration determination unit executes a session establishment process to establish a session using a second or subsequent wireless access network to be used for the multi-access session when the NW registration information indicates that the user terminal is already registered in two or more wireless access networks.

[0024] One aspect of the present invention is a user terminal of a mobile communication system having a core network connected to multiple radio access networks, the user terminal comprising: a multi-access session configuration capability information storage unit that stores multi-access session configuration capability information indicating which combination of radio access networks among the multiple radio access networks the user terminal has the capability to establish a multi-access session with; and a multi-access session control unit that notifies the core network of the multi-access session configuration capability information.

[0025] One aspect of the present invention is a user terminal of a mobile communication system having a core network connected to multiple radio access networks, the user terminal comprising: a multi-access session priority information memory unit that stores multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established by the user terminal between the core network; and a multi-access session control unit that notifies the core network of the multi-access session priority information.

[0026] One aspect of the present invention is a network device provided in a core network in a mobile communications system connected to a plurality of radio access networks, the network device comprising: a multi-access session priority information management unit that manages multi-access session priority information indicating a priority of a radio access network to be used for a multi-access session established by a user terminal between the core network, and provides the multi-access session priority information to a network device having a multi-access session configuration determination unit that determines a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information.

[0027] One aspect of the present invention is a communication method executed by a network device provided in a core network in a mobile communications system having the core network connected to a plurality of radio access networks, the communication method including: a measurement information acquisition step of acquiring measurement information indicating communication quality of each of the plurality of radio access networks; and a multi-access session configuration determination step of determining, based on the measurement information, a radio access network from the plurality of radio access networks to be used for a multi-access session established by a user terminal between the core network.

[0028] One aspect of the present invention is a communication method executed by a network device provided in a core network in a mobile communications system having a core network connected to a plurality of radio access networks, the communication method including: a multi-access session priority information storage step of storing multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established by a user terminal between the core network and the multi-access session priority information storage unit; and a multi-access session configuration determination step of determining a radio access network to be used for the multi-access session from the plurality of radio access networks based on the multi-access session priority information.

[0029] One aspect of the present invention is a computer program for causing a computer of a network device provided in a mobile communications system having a core network connected to a plurality of radio access networks to execute a measurement information acquisition step of acquiring measurement information indicating communication quality of each of the plurality of radio access networks, and a multi-access session configuration determination step of determining, based on the measurement information, a radio access network to be used from among the plurality of radio access networks for a multi-access session established by a user terminal between the core network.

[0030] One aspect of the present invention is a computer program for causing a computer of a network device provided in a core network in a mobile communications system connected to a plurality of radio access networks to execute a multi-access session priority information storage step of storing multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established by a user terminal between the core network and the multi-access session priority information storage unit, and a multi-access session configuration determination step of determining a radio access network to be used for the multi-access session from the plurality of radio access networks based on the multi-access session priority information.

[0031] One aspect of the present invention is a computer program for causing a computer of a user terminal of a mobile communications system having a core network connected to multiple radio access networks to execute a multi-access session configuration capability information storage step of storing multi-access session configuration capability information indicating which combination of radio access networks among the multiple radio access networks the user terminal has the capability of establishing a multi-access session with in a multi-access session configuration capability information storage unit, and a multi-access session control step of notifying the core network of the multi-access session configuration capability information.

[0032] One aspect of the present invention is a computer program for causing a computer of a user terminal of a mobile communication system having a core network connected to multiple radio access networks to execute a multi-access session priority information storage step of storing multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established by the user terminal between the core network and a multi-access session priority information storage unit, and a multi-access session control step of notifying the core network of the multi-access session priority information.

[0033] One aspect of the present invention is a computer program for causing a computer of a network device provided in a core network in a mobile communications system connected to a plurality of radio access networks to execute a multi-access session priority information management step of managing multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established by a user terminal between the core network, and providing the multi-access session priority information to a network device provided with a multi-access session configuration determination unit that determines a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information. Effect of the Invention

[0034] According to the present invention, it is possible to obtain an effect that a multi-access session can be appropriately configured. [Brief description of the drawings]

[0035] [Figure 1] 1 is a block diagram showing a configuration example of a mobile communication system according to an embodiment. [Diagram 2] FIG. 1 is a diagram showing a schematic configuration of a user equipment (UE) according to an embodiment. [Diagram 3] 11 is a diagram illustrating an example of a configuration of a multi-access session information management table according to an embodiment; [Figure 4] 1 is a diagram showing a schematic configuration of a session control device according to an embodiment; [Diagram 5] 1 is a diagram showing a schematic configuration of a contractor information management device according to an embodiment; [Figure 6] FIG. 1 is a diagram illustrating a schematic configuration of a base station device according to an embodiment. [Figure 7] FIG. 2 is a sequence diagram showing an overall flow of a communication method according to an embodiment. [Figure 8]FIG. 1 illustrates an example of a multi-access session configuration identification method according to an embodiment. [Figure 9] FIG. 1 is a diagram showing a schematic architecture of a conventional 5G system. [Figure 10] A diagram showing an example of the configuration of "MA PDU Session". [Figure 11] FIG. 1 is a diagram illustrating an example of a configuration of DC (Dual Connectivity). [Figure 12] FIG. 13 is a diagram illustrating an example of the configuration of a multi-access session. [Figure 13] FIG. 13 is a diagram illustrating an example of the configuration of a multi-access session. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing a configuration example of a mobile communication system according to an embodiment. In Fig. 1, a UE (user equipment) 10 can be connected to a RAN (radio access network) 30 (30_1, 30_2) which is "3gpp access". Examples of the RAN 30 include a base station (4G base station) of a fourth generation mobile communication system (4G system) and a base station (5G base station) of a 5G system.

[0037] The RAN 30_1 is a RAN of a first PLMN. The RAN 30_2 is a RAN of a second PLMN. The first PLMN and the second PLMN may be the same PLMN (i.e., the same communication carrier) or different PLMNs (i.e., different communication carriers). The RAN 30 (30_1, 30_2) is connected to a UPF (User Plane Function) 60 of a CN (Core Network) of the mobile communication system 1.

[0038] Hereinafter, when there is no particular distinction between the RAN 30_1 and the RAN 30_2, they will be referred to as the RAN 30. Furthermore, the CN of the mobile communication system 1 will sometimes be simply referred to as the CN. Furthermore, the UPF 60 of the CN of the mobile communication system 1 will sometimes be simply referred to as the UPF 60.

[0039] Although only two RANs 30 (30_1, 30_2) are shown in FIG. 1, the mobile communication system 1 may include three or more RANs 30 (30_1, 30_2, 30_3, ...) connected to the UPF 60, and the UE 10 may be connectable to three or more RANs 30 (30_1, 30_2, 30_3, ...). In this case, all the RANs 30 (30_1, 30_2, 30_3, ...) may or may not be the same PLMN. Furthermore, all the RANs 30 (30_1, 30_2, 30_3, ...) are connected to the UPF 60.

[0040] Furthermore, the UE 10 is connectable to a wireless LAN 80 that is a "non-3gpp access". The wireless LAN 80 is connected to the UPF 60. The wireless LAN 80 is an example of a wireless access network that is a "non-3gpp access".

[0041] The UPF 60 is connected to a DN (data network) outside the CN, such as the Internet.

[0042] The UE 10 can establish a session with the UPF 60 using a wireless path via the RAN 30 or the wireless LAN 80, and can transmit and receive data to and from the DN using the established session. The UE 10 can also establish a multi-access session with the UPF 60 using a wireless path via the RAN 30 and a wireless path via the wireless LAN 80, and can transmit and receive data to and from the DN using the established multi-access session.

[0043] In the present embodiment, the UE 10 is further intended to be able to establish a multi-access session with the UPF 60 using a plurality of wireless paths via each of a plurality of RANs 30. Also, two "3gpp accesses" for establishing the multi-access session are appropriately selected. Also, when the UE 10 is registered in two "3gpp accesses" and one "non-3gpp access", an appropriate configuration of the multi-access session is determined.

[0044] In addition, in this embodiment, the UE 10 can use DC (Dual Connectivity). Therefore, there is a possibility that the multi-access session will not be effectively used due to DC. Therefore, in this embodiment, it is intended to effectively use the multi-access session.

[0045] The AM (Access and Mobility) control device 50 is a network device that realizes one NF (network function) of the control plane (C-plane) of the mobile communication system 1. The AM control device 50 is a network device that realizes an NF corresponding to the AMF of, for example, 5GC (CN of a 5G system). The AM control device 50 performs communication on the C-plane between the UE 10 and the RAN 30. In addition, the AM control device 50 performs communication on the C-plane of the CN with the session control device 51.

[0046] The session control device 51 is a network device that realizes one NF of the C-plane of the mobile communication system 1. The session control device 51 is a network device that realizes an NF corresponding to the SMF of 5GC (CN of the 5G system), for example. However, in this embodiment, the session control device 51 is a network device that realizes a new additional NF in addition to the SMF of 5GC.

[0047] The session control device 51 performs communication on the C-plane with the UPF 60. In addition, the session control device 51 performs communication with the subscriber information management device 52 on the C-plane of the CN.

[0048] 2 is a diagram showing a schematic configuration of a UE according to this embodiment. In FIG. 2, the UE 10 includes a control unit 110, a storage unit 120, a communication unit 130, a display unit 140, and an operation unit 150.

[0049] The control unit 110 is a CPU (Central Processing Unit), and realizes various functions by calling and executing programs stored in the storage unit 120 .

[0050] The control unit 110 includes, as one of its functions, a multi-access session control unit 1111. The multi-access session control unit 1111 is realized by the CPU executing a multi-access session control program 1210 stored in the storage unit 120.

[0051] 2 shows only a multi-access session control unit 1111 added from the conventional UE 10 as a function of the control unit 110. Similarly, as a program stored in the storage unit 120, only a multi-access session control program 1210 added from the conventional UE 10 is shown.

[0052] The storage unit 120 is configured by a storage medium, for example, a hard disk drive (HDD), a flash memory, an electrically erasable programmable read only memory (EEPROM), a random access read / write memory (RAM), a read only memory (ROM), or an arbitrary combination of these storage media. The storage unit 120 stores various programs such as a multi-access session control program 1210 executed by the control unit 110 (CPU), and various data.

[0053] The communication unit 130 connects to a base station of the RAN 30 and performs wireless communication via the connected base station. The communication unit 130 also connects to an access point of the wireless LAN 80 and performs wireless communication via the connected access point.

[0054] Display unit 140 includes a display element such as a liquid crystal display or an organic EL (Electro Luminescence) display, and displays display data output from control unit 110. Operation unit 150 is configured with an input device such as a numeric keypad, and inputs data in response to a user's operation. Alternatively, UE 10 may include a touch panel capable of both data input and data display.

[0055] The storage unit 120 stores a multi-access session information management table 1220. Fig. 3 is a diagram showing an example of the configuration of the multi-access session information management table according to this embodiment. In Fig. 3, the multi-access session information management table 1220 is a table that stores multi-access session configuration capability information and multi-access session priority information.

[0056] The multi-access session configuration capability information is information indicating which combination of radio access networks among a plurality of radio access networks (RAN 30_1, 30_2, and wireless LAN 80) the UE 10 has the capability of establishing a multi-access session. The multi-access session configuration capability information is set in the UE 10 in advance.

[0057] The multi-access session priority information is information indicating the priority of a radio access network used for a multi-access session established between the UE 10 and the CN (UPF 60). The multi-access session priority information is set in the UE 10 in advance.

[0058] The multi-access session control unit 1111 has a function of notifying the CN of multi-access session configuration capability information stored in the multi-access session information management table 1220. The multi-access session control unit 1111 has a function of notifying the CN of multi-access session priority information stored in the multi-access session information management table 1220.

[0059] FIG. 4 is a diagram showing a schematic configuration of a session control device according to this embodiment. The session control device 51 shown in FIG. 4 is a device corresponding to the SMF of 5GC. In this embodiment, the session control device 51 further includes a multi-access session configuration identification unit 511, a multi-access session configuration determination unit 512, a DC control information transmission unit 513 for a multi-access session, a measurement information acquisition unit 514, and a multi-access session priority information storage unit 515 as additional parts from the SMF of 5GC in addition to the functions of the SMF of 5GC. Note that FIG. 4 shows only the multi-access session configuration identification unit 511, the multi-access session configuration determination unit 512, the DC control information transmission unit 513 for a multi-access session, the measurement information acquisition unit 514, and the multi-access session priority information storage unit 515 as additional parts from the SMF of 5GC as functions of the session control device 51.

[0060] Each function of the session control device 51 is realized by the session control device 51 including computer hardware such as a CPU and a memory, and the CPU executing a computer program stored in the memory. The session control device 51 may be configured using a general-purpose computer device, or may be configured as a dedicated hardware device. For example, the session control device 51 may be configured using a server computer connected to a communication network. Each function of the session control device 51 may be realized by cloud computing. The session control device 51 may be realized by a single computer, or may be realized by distributing the functions of the session control device 51 among multiple computers.

[0061] The multi-access session configuration identification unit 511 identifies the configuration of the multi-access session that the UE 10 establishes with the CN (UPF 60) based on the multi-access session configuration capability information notified from the UE 10 and the network registration information (NW registration information) indicating the wireless access network in which the UE 10 is registered among multiple wireless access networks (RAN 30_1, 30_2, wireless LAN 80).

[0062] The multi-access session configuration determining unit 512 determines, from among a plurality of radio access networks (the RANs 30_1, 30_2, and the wireless LAN 80), a radio access network to be used for the multi-access session that the UE 10 establishes with the CN (UPF 60). For example, the multi-access session configuration determining unit 512 determines a radio access network to be used for a multi-access session that the UE 10 establishes with the CN (UPF 60) based on measurement information indicating communication quality of each of the multiple radio access networks (RAN 30_1, 30_2, wireless LAN 80). The measurement information is acquired by the measurement information acquiring unit 514. For example, the multi-access session configuration determination unit 512 determines the radio access network to be used for the multi-access session that the UE 10 establishes with the CN (UPF 60) based on the multi-access session priority information.

[0063] When a multi-access session established between the UE 10 and the CN (UPF 60) satisfies a specific multi-access session condition, the multi-access session DC control information transmission unit 513 transmits, to a base station of a radio access network to which the UE 10 is connected, DC control information for a multi-access session indicating a combination of base stations that prohibit DC for the UE 10. Specifically, when a multi-access session established between the UE 10 and the CN (UPF 60) uses multiple "3gpp accesses", the multi-access session DC control information transmission unit 513 transmits the multi-access session DC control information for the UE 10.

[0064] Further, the DC control information transmission unit 513 for a multi-access session controls transmission of the DC control information for the multi-access session for the UE 10 based on a steering mode indicating a policy of the multi-access session for the UE 10. As an example of control of transmission of the DC control information for the multi-access session according to the present embodiment, the DC control information transmission unit 513 for a multi-access session transmits the DC control information for the multi-access session for the UE 10 when the steering mode of the UE 10 is a specific mode in a case where the multi-access session established between the UE 10 and the CN (UPF 60) uses a plurality of "3gpp accesses". Specifically, the DC control information transmission unit 513 for a multi-access session transmits the DC control information for the multi-access session for the UE 10 when the steering mode of the UE 10 is "Load-Balancing" or "Redundant" in a case where the multi-access session established between the UE 10 and the CN (UPF 60) uses a plurality of "3gpp accesses".

[0065] The measurement information acquisition unit 514 acquires measurement information indicating the communication quality of each of the multiple wireless access networks (RAN 30_1, 30_2, wireless LAN 80). The communication quality is, for example, a throughput, an RTT, a packet loss rate, etc. The measurement function is, for example, possessed by the UPF in a 5G system. As an example of this embodiment, the UPF 60 has the measurement function, and the measurement information acquisition unit 514 acquires the measurement information from the UPF 60.

[0066] The multi-access session priority information storage unit 515 stores the multi-access session priority information of the UE 10. The multi-access session priority information is provided from the subscriber information management device 52 or the UE 10. Alternatively, the multi-access session priority information may be set in advance in the session control device 51 as a unique value for each communication carrier (PLMN).

[0067] Fig. 5 is a diagram showing a schematic configuration of a contractor information management device according to this embodiment. The contractor information management device 52 shown in Fig. 5 is a device compatible with the 5GC UDM. In this embodiment, the contractor information management device 52 includes a multi-access session priority information management unit 521 as an additional part from the 5GC UDM in addition to the functions of the 5GC UDM. Note that Fig. 5 shows only the multi-access session priority information management unit 521 added from the 5GC UDM as a function of the contractor information management device 52.

[0068] Each function of the contractor information management device 52 is realized by the contractor information management device 52 having computer hardware such as a CPU and a memory, and the CPU executing a computer program stored in the memory. The contractor information management device 52 may be configured using a general-purpose computer device, or may be configured as a dedicated hardware device. For example, the contractor information management device 52 may be configured using a server computer connected to a communication network. Each function of the contractor information management device 52 may be realized by cloud computing. The contractor information management device 52 may be realized by a single computer, or may be realized by distributing the functions of the contractor information management device 52 among multiple computers.

[0069] The multi-access session priority information management unit 521 manages and stores multi-access session priority information for each UE 10. The multi-access session priority information management unit 521 has a function of providing the multi-access session priority information of each UE 10 to the session control device 51.

[0070] Fig. 6 is a diagram showing a schematic configuration of a base station device according to this embodiment. The base station device 30bs shown in Fig. 6 is a base station device corresponding to the RAN 30, which is "3gpp access". Hereinafter, the base station device 30bs may be referred to as a base station 30bs.

[0071] In this embodiment, the base station 30bs includes a DC control information storage unit 302 for multi-access sessions as an additional part from the "3gpp access" base station, in addition to the functions of the "3gpp access" base station (for example, a 4G base station or a 5G base station). The base station 30bs also adds a change to the DC control unit 301, which is one function of the "3gpp access" base station. Note that FIG. 6 shows only the DC control unit 301 and the DC control information storage unit 302 for multi-access sessions added from the "3gpp access" base station, as functions of the base station 30bs.

[0072] The multi-access session DC control information storage unit 302 stores the multi-access session DC control information for each UE 10. The multi-access session DC control information is notified for each UE 10 from the session control device 51 (multi-access session DC control information transmission unit 513).

[0073] The DC control unit 301 controls the DC of the UE 10 connected to its own base station 30bs. The DC control unit 301 controls the DC of the UE 10 that is the DC control target based on the DC control information for the multi-access session of the UE 10 that is the DC control target stored in the DC control information storage unit 302 for the multi-access session. Specifically, the DC control unit 301 controls the UE 10 that is the DC control target not to perform the DC of the UE 10 that is the DC control target in the "combination of base stations that prohibits DC" indicated in the DC control information for the multi-access session of the UE 10 that is the DC control target.

[0074] Next, a communication method according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a sequence diagram showing the overall flow of the communication method according to this embodiment.

[0075] The UE 10 is connected to a base station (BS) 30bs_1 of a first PLMN with which the UE 10 has already been network registered (NW registered).

[0076] (Step S1) The multi-access session control unit 1111 of the UE 10 transmits a multi-access session establishment request to the AM control device 50 via the base station 30bs_1. At this time, the multi-access session control unit 1111 includes the multi-access session configuration capability information of the multi-access session information management table 1220 in the multi-access session establishment request transmitted to the AM control device 50. Furthermore, the multi-access session control unit 1111 may include the multi-access session priority information of the multi-access session information management table 1220 in the multi-access session establishment request.

[0077] (Step S2) The AM control device 50 selects a session control device 51 that executes a session establishment process in response to the multi-access session establishment request (including multi-access session configuration capability information) received from the UE 10, and transfers the multi-access session establishment request (including multi-access session configuration capability information) together with network registration information (NW registration information) to the selected session control device 51. The NW registration information is information indicating all "3gpp access" and "non-3gpp access" for which the UE 10 has been registered on the NW. The AM control device 50 manages the state of NW registration for each UE 10.

[0078] (Step S3) The session control device 51 receives the NW registration information and the multi-access session establishment request (including the multi-access session configuration capability information) transmitted from the AM control device 50. The multi-access session configuration identification unit 511 of the session control device 51 identifies the configuration of the multi-access session that the UE 10 that has made the multi-access session establishment request (requesting UE 10) establishes with the CN (UPF 60) based on the received NW registration information and multi-access session configuration capability information.

[0079] Here, a multi-access session configuration identification method according to this embodiment will be described. FIG. 8 is a diagram showing an example of the multi-access session configuration identification method according to this embodiment. FIG. 8 shows a multi-access session configuration corresponding to each combination of NW registration information and multi-access session configuration capability information. The multi-access session configuration identification method shown in FIG. 8 is set in advance in the multi-access session configuration identification unit 511. The multi-access session configuration identification unit 511 identifies the multi-access session configuration corresponding to the NW registration information and the multi-access session configuration capability information for the request source UE 10 according to the multi-access session configuration identification method of FIG. 8.

[0080] In the multi-access session configuration identification method of Figure 8, in the case of a combination of NW registration information "one 3gpp & one non-3gpp (one "3gpp access" and one "non-3gpp access")" and multi-access session configuration capability information "3gpp+ non-3gpp (a multi-access session can be configured with a combination of "3gpp access" and "non-3gpp access")", the multi-access session configuration is "3gpp+ non-3gpp (a combination of "3gpp access" and "non-3gpp access")". In addition, in the case of a combination of NW registration information "one 3gpp & one non-3gpp" and multi-access session configuration capability information "3gpp+non-3gpp&3gpp+3gpp (a multi-access session can be configured with either the combination of "3gpp access" and "non-3gpp access", or the combination of "3gpp access" and "3gpp access")", the multi-access session configuration is "3gpp+ non-3gpp (the combination of "3gpp access" and "non-3gpp access")".

[0081] In addition, in the case of a combination of NW registration information "two 3gpp (two "3gpp access")" and multi-access session configuration capability information "3gpp+3gpp (a multi-access session can be configured with a combination of "3gpp access" and "3gpp access")," the multi-access session configuration is "3gpp+3gpp (a combination of "3gpp access" and "3gpp access")." In addition, in the case of a combination of the NW registration information "two 3gpp" and the multi-access session configuration capability information "3gpp+non-3gpp&3gpp+3gpp", the multi-access session configuration is "3gpp+3gpp".

[0082] In addition, in the case of a combination of NW registration information "two 3gpp & one non-3gpp (two '3gpp access' and one 'non-3gpp access')" and multi-access session configuration capability information "3gpp+ non-3gpp", the multi-access session configuration is "3gpp+ non-3gpp". In addition, in the case of a combination of the NW registration information "two 3gpp & one non-3gpp" and the multi-access session configuration capability information "3gpp+3gpp", the multi-access session configuration is "3gpp+3gpp".

[0083] In the multi-access session configuration identification method of FIG. 8, the cases where the multi-access session configuration is "session established only on the 3GPP side" and "determined based on measurement information or priority information" will be described later.

[0084] Multi-access session configuration determination section 512 of session control device 51 determines a radio access network for the multi-access session configuration of request source UE 10 identified by multi-access session configuration identification section 511 (the identification result of the multi-access session configuration).

[0085] (Step S4) The multi-access session configuration determination unit 512 determines a steering mode indicating how traffic is transmitted between multiple sessions of the multi-access session for the multi-access session configuration of the requestor UE 10. Examples of the steering mode according to this embodiment include steering modes (1)-(5) defined in Non-Patent Documents 1 and 2.

[0086] (Steps S5 and S6) The multi-access session configuration determination unit 512 executes a session establishment process for the multi-access session configuration of the requesting UE 10. In one example of this session establishment process, the multi-access session configuration determination unit 512 establishes a session (first session) on the radio access network to which the requesting UE 10 has transmitted the multi-access session establishment request. At this time, the multi-access session configuration determination unit 512 transmits a set of information necessary for multi-access session control, including steering mode information indicating the steering mode determined in step S4, to the requesting UE 10 (step S6). The multi-access session configuration determination unit 512 also transmits the set of information to the gateway device (UPF 60) (not shown).

[0087] After the first session is established, if the request source UE 10 has already been registered in the second wireless access network according to the NW registration information of the request source UE 10, the multi-access session configuration determination unit 512 establishes a session (second session) in the second wireless access network in the same manner as the first session. In the session establishment process, for example, exchange of tunnel information between the base station and the gateway device is performed.

[0088] Here, in the multi-access session configuration identification method of Figure 8 described above, we will explain the case of the multi-access session configuration "session established only on the 3gpp side" corresponding to the combination of NW registration information "one 3gpp & one non-3gpp" and multi-access session configuration capability information "3gpp+3gpp", and the combination of NW registration information "two 3gpp" and multi-access session configuration capability information "3gpp+ non-3gpp".

[0089] In this embodiment, as in the conventional "MA PDU Session", the UE 10 can execute a multi-access session establishment request in a state where the UE 10 has already been registered in only one of the radio access networks, one "3gpp access" and one "non-3gpp access". At this time, the CN determines various information required for the multi-access session (e.g., an IP (Internet Protocol) address to be provided to the UE 10 and proxy information on the CN side, etc.) and establishes a session for the UE 10 only in the "3gpp access" in which the UE 10 has already been registered. As soon as the UE 10 completes network registration in the other unregistered radio access network, the UE 10 immediately executes a session establishment request in the radio access network in which the network registration has been completed. In this session establishment request, the UE 10 presents the same session ID as the session already established as a multi-access session. As a result, the CN recognizes that the session establishment request from the UE 10 in which the session ID is presented is a session establishment request to be used for the multi-access session of the UE 10. Conventionally, the steering mode is notified from the CN to the UE when the “MA PDU Session” is established. In this embodiment, the CN notifies the UE 10 of the steering mode when at least the second session is established.

[0090] In addition, in the multi-access session configuration identification method of Fig. 8 described above, a case of a multi-access session configuration "determined by measurement information or priority information" corresponding to a combination of NW registration information "two 3gpp & one non-3gpp" and multi-access session configuration capability information "3gpp+non-3gpp&3gpp+3gpp" will be described. In this case, a multi-access session can be formed with either "3gpp+3gpp" or "3gpp+non-3gpp". Below, a case of a multi-access session configuration "determined by measurement information" and a case of a multi-access session configuration "determined by priority information" will be described respectively. In the session control device 51, it is set in advance whether to use "determined by measurement information" or "determined by priority information".

[0091] In the multi-access session configuration "determined by measurement information", the multi-access session configuration determination unit 512 determines a radio access network to be used for the multi-access session of the request source UE 10 from among two "3gpp accesses" and one "non-3gpp access" based on the measurement information acquired by the measurement information acquisition unit 514. For example, the multi-access session configuration determination unit 512 compares the measurement information of the two "3gpp accesses" and one "non-3gpp access" and determines a radio access network to be used for the multi-access session of the request source UE 10 based on the result of the comparison.

[0092] In the multi-access session configuration "determined based on priority information", the multi-access session configuration determination unit 512 determines the radio access network to be used for the multi-access session of the requesting UE 10 from among two "3gpp access" and one "non-3gpp access" based on the multi-access session priority information stored in the multi-access session priority information storage unit 515.

[0093] (Step S7) When the multi-access session of the requestor UE 10 satisfies a specific multi-access session condition, the multi-access session DC control information transmission unit 513 of the session control device 51 transmits the multi-access session DC control information for the requestor UE 10 to the base station of the radio access network to which the requestor UE 10 is connected.

[0094] The DC control information for the multi-access session for the request source UE 10 is information indicating a combination of base stations that prohibit DC for the request source UE 10. The combination of base stations that prohibit DC for the request source UE 10 is a combination of base stations of a radio access network that can be used for a multi-access session of the request source UE 10. For example, the DC control information for the multi-access session for the request source UE 10 is information indicating a combination of all base stations to which the request source UE 10 is connected in a radio access network that can be used for a multi-access session of the request source UE 10.

[0095] An example of a specific multi-access session condition according to the present embodiment is that the multi-access session uses multiple "3gpp access" and the steering mode is a specific mode. Furthermore, the specific steering mode is "Load-Balancing" or "Redundant".

[0096] For example, when the multi-access session of the request source UE 10 uses multiple "3gpp access" and the steering mode is "Load-Balancing" or "Redundant", the multi-access session DC control information transmission unit 513 transmits the multi-access session DC control information related to the request source UE 10 to a base station of a radio access network to which the request source UE 10 is connected. The base station receives the multi-access session DC control information and stores the received multi-access session DC control information in the multi-access session DC control information storage unit 302 in association with the identifier of the request source UE 10.

[0097] (Step S8) The base station of the radio access network to which the requesting UE 10 is connected controls the DC of the requesting UE 10 so as not to perform DC in the "combination of base stations for which DC is prohibited" indicated in the DC control information for the multi-access session stored in the DC control information storage unit 302 for the multi-access session.

[0098] According to the above-described embodiment, an effect is obtained in that a multi-access session can be appropriately configured.

[0099] According to the above-described embodiment, it is possible to control the DC of the UE 10 in accordance with the multi-access session of the UE 10.

[0100] According to the above-described embodiment, it is possible to obtain an effect that multi-access sessions can be effectively utilized.

[0101] The above-described embodiments are applicable to mobile communication systems such as 5G systems, B5G systems, and 6G systems.

[0102] This will, for example, make it possible to improve the overall service quality of mobile communications systems, thereby contributing to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0103] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present invention are also included.

[0104] Also, a computer program for implementing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Note that the "computer system" referred to here may include hardware such as an OS and peripheral devices. Also, the "computer-readable recording medium" refers to a flexible disk, a magneto-optical disk, a ROM, a writable non-volatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disc), and a storage device such as a hard disk built into a computer system.

[0105] Furthermore, the term "computer-readable recording medium" includes a memory that holds a program for a certain period of time, such as a volatile memory (e.g., DRAM (Dynamic Random Access Memory)) inside a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. The above-mentioned program may be transmitted from a computer system that stores the program in a storage device or the like to another computer system via a transmission medium, or by a transmission wave in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The above-mentioned program may be a program for realizing part of the above-mentioned functions. Furthermore, the above-mentioned function may be realized in combination with a program already recorded in the computer system, that is, a so-called difference file (difference program). [Explanation of symbols]

[0106] 1...mobile communication system, 10...UE, 30...RAN, 50...AM control device, 51...session control device, 52...contractor information management device, 60...UPF, 70...DN, 80...wireless LAN, 110...control device, 120...storage unit, 130...communication unit, 140...display unit, 150...operation unit, 1111...multi-access session control unit, 1210...multi-access session control program, 1220...multi-access session information management table, 511...multi-access session configuration identification unit, 512...multi-access session configuration determination unit, 513...multi-access session DC control information transmission unit, 514...measurement information acquisition unit, 515...multi-access session priority information storage unit, 521...multi-access session priority information management unit, 30bs...base station device, 301...DC control unit, 302...multi-access session DC control information storage unit

Claims

1. A network device provided in a core network in a mobile communication system including a core network connected to a plurality of radio access networks, comprising: a measurement information acquiring unit for acquiring measurement information indicating a communication quality of each of the plurality of wireless access networks; a multi-access session configuration determination unit that determines, based on the measurement information, from among the plurality of radio access networks, a radio access network to be used for a multi-access session established between the user terminal and the core network; A network device comprising:

2. A network device provided in a core network in a mobile communication system including a core network connected to a plurality of radio access networks, comprising: a multi-access session priority information storage unit configured to store multi-access session priority information indicating a priority of a radio access network used for a multi-access session established between a user terminal and the core network; a multi-access session configuration determination unit that determines a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information; A network device comprising:

3. Further, a multi-access session configuration identification unit is provided that identifies a configuration of a multi-access session that the user terminal establishes with the core network based on multi-access session configuration capability information indicating which combination of radio access networks among the plurality of radio access networks the user terminal has the capability of establishing a multi-access session with and NW registration information indicating a radio access network among the plurality of radio access networks in which the user terminal is registered; The multi-access session configuration determination unit determines a radio access network for the identification result of the multi-access session configuration.

3. A network device according to claim 1 or 2.

4. When the NW registration information indicates that the user terminal has been registered in two or more wireless access networks, the multi-access session configuration determination unit executes a session establishment process for establishing a session by a second or subsequent wireless access network to be used for the multi-access session. The network device according to claim 3 .

5. A user terminal of a mobile communication system including a core network connected to a plurality of radio access networks, a multi-access session configuration capability information storage unit configured to store multi-access session configuration capability information indicating which combination of radio access networks among the plurality of radio access networks the user terminal has the capability of establishing a multi-access session; a multi-access session control unit that notifies the core network of the multi-access session configuration capability information; A user terminal comprising:

6. A user terminal of a mobile communication system including a core network connected to a plurality of radio access networks, a multi-access session priority information storage unit configured to store multi-access session priority information indicating a priority of a radio access network used for a multi-access session established between the user terminal and the core network; a multi-access session control unit that notifies the core network of the multi-access session priority information; A user terminal comprising:

7. A network device provided in a core network in a mobile communication system including a core network connected to a plurality of radio access networks, comprising: a multi-access session priority information management unit that manages multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established between a user terminal and the core network, and provides the multi-access session priority information to a network device including a multi-access session configuration determination unit that determines a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information; A network device comprising:

8. A communication method executed by a network device in a core network in a mobile communication system including a core network connected to a plurality of radio access networks, comprising: a measurement information acquisition step of acquiring measurement information indicating a communication quality of each of the plurality of wireless access networks; a multi-access session configuration determination step of determining, from among the plurality of radio access networks, a radio access network to be used for a multi-access session established between the user terminal and the core network based on the measurement information; A communication method including:

9. A communication method executed by a network device in a core network in a mobile communication system including a core network connected to a plurality of radio access networks, comprising: a multi-access session priority information storage step of storing, in a multi-access session priority information storage unit, multi-access session priority information indicating a priority of a radio access network used for a multi-access session established between a user terminal and the core network; a multi-access session configuration determination step of determining a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information; A communication method including:

10. In a mobile communication system having a core network connected to a plurality of radio access networks, a computer of a network device provided in the core network, a measurement information acquisition step of acquiring measurement information indicating a communication quality of each of the plurality of wireless access networks; a multi-access session configuration determination step of determining, from among the plurality of radio access networks, a radio access network to be used for a multi-access session established between the user terminal and the core network based on the measurement information; A computer program for executing the above.

11. In a mobile communication system having a core network connected to a plurality of radio access networks, a computer of a network device provided in the core network, a multi-access session priority information storage step of storing, in a multi-access session priority information storage unit, multi-access session priority information indicating a priority of a radio access network used for a multi-access session established between a user terminal and the core network; a multi-access session configuration determination step of determining a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information; A computer program for executing the above.

12. A computer of a user terminal of a mobile communication system having a core network connected to a plurality of radio access networks, a multi-access session configuration capability information storage step of storing, in a multi-access session configuration capability information storage unit, multi-access session configuration capability information indicating which combination of radio access networks among the plurality of radio access networks the user terminal has the capability of establishing a multi-access session with; a multi-access session control step of notifying the core network of the multi-access session configuration capability information; A computer program for executing the above.

13. A computer of a user terminal of a mobile communication system having a core network connected to a plurality of radio access networks, a multi-access session priority information storage step of storing, in a multi-access session priority information storage unit, multi-access session priority information indicating a priority of a radio access network used for a multi-access session established between the user terminal and the core network; a multi-access session control step of notifying the core network of the multi-access session priority information; A computer program for executing the above.

14. In a mobile communication system having a core network connected to a plurality of radio access networks, a computer of a network device provided in the core network, a multi-access session priority information management step of managing multi-access session priority information indicating the priority of a radio access network to be used for a multi-access session established between a user terminal and the core network, and providing the multi-access session priority information to a network device including a multi-access session configuration determination unit that determines a radio access network to be used for the multi-access session from among the plurality of radio access networks based on the multi-access session priority information; A computer program for executing the above.

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