Mobile communication systems, network devices, terminal devices, communication methods, and computer programs

Abstract

To ensure an appropriate communication path when a communication device connects to two different generations of "3GPP access" simultaneously. [Solution] A mobile communication system equipped with two different generation wireless access networks to which a terminal can connect simultaneously includes an SM node that selects a "DS-capable GW," which is the gateway at each location of a "DS-capable NW," capable of establishing a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that does not support "DualSteer," to which the terminal is currently connected or could connect.

Description

Technical Field

[0001] The present invention relates to a mobile communication system, a network device, a terminal device, a communication method, and a computer program.

Background Art

[0002] Conventionally, a fifth-generation mobile communication system (5G system) standardized by "3GPP (registered trademark) (3rd Generation Partnership Project)" is known (see, for example, Non-Patent Documents 1 and 2). FIG. 6 is a diagram showing a schematic architecture of the 5G system. In FIG. 6, the 5G system is composed of various NFs (Network Functions) such as a UE (User Equipment, user terminal), a RAN (Radio Access Network, radio access network), a UPF (User Plane Function) of a CN (Core Network, core network), and a control plane (Control plane: C-plane) of the CN. Examples of the NFs in the C-plane of the CN include an AMF (Access and Mobility Management Function), an SMF (Session Management Function), a PCF (Policy Control Function), a UDM (Unified Data Management), a UDR (Unified Data Repository), and the like.

[0003] Here, the logical communication path that a UE establishes with a CN (UPF) to use mobile communication services is referred to as a "session." Furthermore, a session established by a UE with a CN (UPF) using multiple radio paths is referred to as a "multi-access session." Non-patent documents 1 and 2 define a "Multi-access PDU (Packet Data Unit) Session (hereinafter referred to as "MA PDU Session")" as an example of a multi-access session. The UE establishes an "MA PDU Session" with a CN (UPF) using a radio path via RAN, which is "3gpp access," and a radio path via a wireless LAN (Local Area Network) such as "Wi-Fi®," which is "non-3gpp access." "3gpp access" is an access network defined by 3GPP. "non-3gpp access" is an access network other than "3gpp access." The UE uses its "MA PDU Session" to send and receive data with a DN (Data Network), such as the Internet, outside of 5GC (CN of the 5G system). By using "MA PDU Session," the UE can achieve improved communication quality through effects such as increased communication bandwidth, reduced communication latency, and ensured redundancy of communication channels.

[0004] Furthermore, Non-Patent Document 3 describes a proposed implementation of "DualSteer (DS)" (see, for example, Figure 6.1.13.2-1: "DualSteer solution based on ATSSS and using an external access path"). In "DualSteer (DS)," a communication device connects to two "3gpp access" paths simultaneously and establishes a multi-access session with the UPF.

[0005] The proposed implementation of DS described in Non-Patent Document 3 involves notifying the communication device of the UPF's MultiPath TCP (Transmission Control Protocol: MPTCP) proxy address, and the communication device then sets the MPTCP proxy address as the destination IP (Internet Protocol) address of the uplink traffic on the first PLMN (Public Land Mobile Network), thereby enabling communication between the communication device and the proxy on the second PLMN without impacting the first PLMN. [Prior art documents] [Non-patent literature]

[0006] [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, TR 23.700-54, V1.1.0, 2024-09 [Overview of the project] [Problems that the invention aims to solve]

[0007] By using DS to simultaneously utilize different generations of RANs, communication devices can achieve performance improvements through multi-access communication. Furthermore, it eliminates the need for coordination control between different generations of RANs, as required by conventional multi-access communication technologies such as ENDC (E-UTRA NR Dual Connectivity; a wireless connection method that uses both 4G and 5G), thus offering significant advantages from an investment perspective.

[0008] Furthermore, making the DS described in Non-Patent Document 3 available in combination with "DS-capable networks; mobile core networks that support DS" and "DS-incapable networks; mobile core networks that do not support DS" will contribute to further reducing capital investment in networks.

[0009] However, the proposed implementation of DS described in Non-Patent Document 3 had the problem that the communication delay on the DS-incapable network side could become very large.

[0010] (Task 1) For example, suppose that a 5G gateway (GW) and a 6G (sixth generation) GW exist at base A on the Sea of ​​Japan side of the Tohoku region, and a 4G GW and a 6G GW exist at base B on the Pacific side of the Tohoku region, and that a DS can be configured with a 5G and 6G pair or a 4G and 6G pair. In this case, if the 6G C-plane determines the anchor GW to pair with the 6G GW without considering bases A and B where the candidate 5G GW and 4G GW exist, it may determine a GW at a different base as the anchor GW (for example, determining the 4G GW at base B as the anchor GW for the 6G GW at base A), which could lead to significant communication delay.

[0011] (Task 2) For example, with the conventional, uniform method of assigning proxy IP addresses (the IP addresses of the gateways terminating the DS), depending on the combination of generations of gateways that make up the DS, there is a possibility that the communication path will be significantly rerouted, which can lead to increased communication delays.

[0012] This invention was made in consideration of these circumstances, and its purpose is to realize an appropriate communication path when a communication device is simultaneously connected to two "3GPP access" systems of different generations. [Means for solving the problem]

[0013] One aspect of the present invention is a mobile communication system comprising two wireless access networks of different generations to which a terminal can connect simultaneously, wherein when the terminal requests "MG-DualSteer," which is a "DualSteer" implemented using a combination of two wireless access networks of different generations, the system includes a Session Management (SM) node that selects a "DS-capable GW," which is a gateway at each location of the "DS-capable NW," capable of establishing a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that the terminal is currently connected to or can connect to, and does not support "DualSteer." One aspect of the present invention is a mobile communication system in which the SM node has the function of identifying the generation of the "DS-incapable NW" wireless access network to which the terminal is connected, and the instance of the "DS-incapable GW" which is the gateway to the "DS-incapable NW", from at least one of the existing PLMN identifier, RAT, cell ID, and "Access Type" included in the other access NW identification information that can identify other wireless access networks to which the terminal is connected or can connect, other than the wireless access network to which the terminal has sent a network registration request. One aspect of the present invention is a mobile communication system in which the selected "DS-capable GW" determines an IP address that can realize the optimal communication path from the "DS-incapable NW" that is paired with the "MG-DualSteer" of the terminal to the "DS-capable GW" from at least one of the following pieces of information: an "MG-DualSteer" rule for the "DS-capable GW", other access network identification information that can identify other wireless access networks that the terminal is connected to or can connect to other than the wireless access network from which the terminal has sent a network registration request, and "MG-DualSteer capability" indicating that the terminal supports "MG-DualSteer", and the determined IP address is used as a proxy IP address for the "DS-incapable NW". One aspect of the present invention is a mobile communication system in which the SM node has a database that can identify a "DS-incapable NW" to which the terminal is connected or can connect from other access NW identification information that can identify other wireless access networks to which the terminal is connected or can connect, other than the wireless access network to which the terminal has sent a network registration request. One aspect of the present invention is a mobile communication system in which the terminal includes in the network registration request other access network identification information that can identify other wireless access networks that the terminal is currently connected to or can connect to, other than the wireless access network to which it has sent a network registration request. One aspect of the present invention is a mobile communication system in which the terminal includes in the network registration information update request other access network identification information that can identify other wireless access networks that the terminal is currently connected to or can connect to, other than the wireless access network to which it has sent a network registration request. One aspect of the present invention is a mobile communication system in which the terminal includes in the session establishment request other access network identification information that can identify other wireless access networks that the terminal is connected to or can connect to, other than the wireless access network to which it has sent a network registration request. One aspect of the present invention is a mobile communication system in which the terminal sets the "Request Type" of the session establishment request to "MG-DualSteer". One aspect of the present invention is a mobile communication system in which the terminal manages a proxy IP address for the "DS-incapable NW" as an IP address for uplink communication of the "DS-incapable NW", and uses the said proxy IP address for the "DS-incapable NW" as the destination IP address for traffic destined for the "DS-incapable NW". One aspect of the present invention is a mobile communication system further comprising a node that manages other access network identification information capable of identifying other wireless access networks that are connected to or can be connected to, other than the wireless access network to which the terminal has transmitted a network registration request.

[0014] One aspect of the present invention is a network device for a mobile communication system that includes two wireless access networks of different generations to which a terminal can connect simultaneously, and when the terminal requests "MG-DualSteer," which is a "DualSteer" implemented with a combination of two wireless access networks of different generations, the network device selects a "DS-capable GW," which is a gateway at each location of the "DS-capable NW," capable of establishing a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that does not support "DualSteer" to which the terminal is currently connected or could connect.

[0015] One aspect of the present invention is a terminal device in a mobile communication system comprising two wireless access networks of different generations to which the terminal device can simultaneously connect, wherein the terminal device includes in its network registration request other access network identification information that can identify other wireless access networks to which it is connected or can connect, other than the wireless access network to which it has sent a network registration request.

[0016] One aspect of the present invention is a communication method performed by a mobile communication system having two different generation wireless access networks to which a terminal can connect simultaneously, wherein when the terminal requests "MG-DualSteer," which is a "DualSteer" implemented with a combination of two different generation wireless access networks, the communication method selects a "DS-capable GW," which is a gateway at each location of the "DS-capable NW," capable of establishing a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that does not support "DualSteer" to which the terminal is currently connected or can connect.

[0017] One aspect of the present invention is a computer program for a mobile communication system equipped with two different generation wireless access networks to which a terminal can connect simultaneously, which causes the computer to execute the step of selecting a "DS-capable GW," which is a gateway at each location of a "DS-capable NW," capable of establishing a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that the terminal is currently connected to or can connect to, when the terminal requests "MG-DualSteer," which is "DualSteer" implemented with a combination of two different generation wireless access networks. [Effects of the Invention]

[0018] According to the present invention, when a communication device simultaneously connects to two "3gpp access" of different generations, an effect that an appropriate communication path can be realized is obtained.

Brief Description of Drawings

[0019] [Figure 1] It is a diagram showing a schematic configuration example of a mobile communication system according to an embodiment. [Figure 2] It is a diagram showing a configuration example of a "DS-capable C-plane" and a "DS-incapable C-plane" according to an embodiment. [Figure 3] It is a diagram showing an example of a procedure of a communication method according to an embodiment. [Figure 4] It is a diagram showing an example of a procedure of a communication method according to an embodiment. [Figure 5] It is a diagram showing an example of a procedure of a communication method according to an embodiment. [Figure 6] It is a diagram showing a schematic architecture of a 5G system.

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] In the present embodiment, a communication device (communication device) that communicates with other devices is referred to as a "terminal device (may be simply referred to as a terminal)". The terminal may be a "UE" already defined in 3GPP.

[0022] The present embodiment proposes a method for a terminal to implement DS (DualSteer) with a combination of two "3gpp access" of different generations. This DS is referred to as "MG-DualSteer (Multi-Generation DualSteer)". A session established for MG-DualSteer is referred to as an "MG-DualSteer Session".

[0023] In this embodiment, a mobile core network that supports DS is referred to as a "DS-capable NW," and a mobile core network that does not support DS is referred to as a "DS-incapable NW." If the DS-capable NW is, for example, 6G, then the DS-incapable NW would be a different generation such as 5G, 4G, 3G, ... or 7G, 8G, .... Therefore, "DS-capable xxx" and "DS-incapable xxx" can be said to be information that identifies the generation of the network.

[0024] In this embodiment, the gateway (GW) of the "DS-capable NW" operates as a proxy for the MG-DualSteer. In the mobile network section, the gateway of the "DS-capable NW" and the terminal communicate using the MG-DualSteer. The terminal and the "Remote Host (RH)" on the internet communicate using normal single-path communication such as TCP / UDP. For example, the gateway in 5G is the UPF. The gateway of the mobile core network refers to the network device (node) that serves as the connection point between the "Data Network (DN)" and the mobile core network.

[0025] Figure 1 is a diagram showing a schematic configuration example of the mobile communication system 1 according to this embodiment. Figure 1 shows the architecture of the "MG-DualSteer Session" according to this embodiment.

[0026] The mobile communication system 1 comprises a "DS-capable NW" 20 and a "DS-incapable NW" 30.

[0027] The "DS-capable NW" 20 comprises a wireless access network (NG (Next Generation)-RAN 21), a C-plane ("DS-capable C-plane" 22), and a gateway ("DS-capable GW" 23). The "DS-capable GW" 23 may be present at each location of the "DS-capable NW" 20.

[0028] The "DS-incapable NW" 30 comprises a wireless access network (Legacy-RAN 31), a C-plane ("DS-incapable C-plane" 32), and a gateway ("DS-incapable GW" 33). The "DS-incapable NW" 30 may be present at each of its locations.

[0029] In Figure 1, terminal 10 connects simultaneously to the "DS-capable NW" 20 and the "DS-incapable NW" 30 to perform MG-DualSteer. In this MG-DualSteer, terminal 10 establishes an "MG-DualSteer Session" with the "DS-capable GW" 23. This allows terminal 10 to use DS with the combination of the "DS-capable NW" 20 and the "DS-incapable NW" 30. Terminal 10 sends and receives data to and from RH50 on DN40 via the "DS-capable GW" 23.

[0030] Figure 2 shows an example configuration of the "DS-capable C-plane" 22 and "DS-incapable C-plane" 32 according to this embodiment. In Figure 2, the "DS-capable C-plane" 22 and "DS-incapable C-plane" 32 include an AM (Access and Mobility) node 101, an SM (Session Management) node 102, a user management node 103, and a policy control node 104. Each node is connected to the others so as to be able to communicate. There may be multiple SM nodes 102.

[0031] AM node 101 supports 5G AMF. SM node 102 supports 5G SMF. User management node 103 supports 5G UDM or UDR. Policy control node 104 supports 5G PCF.

[0032] The functions of AM node 101, SM node 102, user management node 103, and policy control node 104 may be configured as a single node in any combination. For example, the functions of AM node 101 and SM node 102 may be configured as a single node. For example, in the case of 4G, the MME (Mobility Management Entity) corresponds to AM node 101 and SM node 102, and the HSS (Home Subscriber Server) corresponds to user management node 103.

[0033] Furthermore, the AM node 101, SM node 102, user management node 103, and policy control node 104 may be functionally divided as desired. For example, the AM node 101 may be functionally divided into an Access node and a Mobility node.

[0034] Furthermore, the "DS-capable C-plane" 22 and the "DS-incapable C-plane" 32 may further include nodes having any other functions besides the AM node 101, SM node 102, user management node 103, and policy control node 104.

[0035] The AM node 101, SM node 102, user management node 103, and policy control node 104 may each be implemented as independent physical servers (information processing devices), or multiple nodes may be implemented on a single physical server. For example, multiple nodes may coexist and be deployed as software on a single physical server.

[0036] Next, the communication method according to this embodiment will be described with reference to Figures 3-5. Figures 3-5 show an example of the procedure of the communication method according to this embodiment.

[0037] [Registration process for MG-DualSteer to "DS-capable NW"] Referring to Figure 3, the registration process for the MG-DualSteer to the "DS-capable NW" 20 will be explained.

[0038] (Step S1) Terminal 10 sends a network (NW) registration request to AM node 101 of "DS-capable C-plane" 22 ("DS-capable AM ​​node" 22_101). This NW registration request may include the following parameters 1-1 and 1-2.

[0039] <Parameter 1-1; Other Access Network Specific Information> Other Access Network Identification Information is information that identifies other RANs that terminal 10 is connected to or can connect to, other than the RAN from which it sent the NW registration request. Other Access Network Identification Information includes identifiers of other networks that can be uniquely identified by the "DS-capable NW" 20. These identifiers of other networks may be existing PLMN (Public Land Mobile Network) identifiers, RAT (Radio Access Type), cell identifiers (cell IDs), "Access Type," etc., or combinations of these. Other Access Network Identification Information may also be in list format. An example of a list format for Other Access Network Identification Information is "NW list = { [ ID = 0, PLMN = xxx, RAT Type = NR, Cell ID = yyy ], [ID = 1, PLMN = zzz, RAT Type = LTE, Cell ID = aaa ]}".

[0040] <Parameters 1-2; "MG-DualSteer capability"> "MG-DualSteer capability" is information indicating that terminal 10 supports MG-DualSteer. "MG-DualSteer capability" may be in list format. "MG-DualSteer capability" may include information such as protocols supported by terminal 10, "Steering modes" supported by terminal 10, and simultaneous transmission capability. Examples of protocols supported by terminal 10 include MPTCP, MPQUIC, and ATSSS-LL. "Steering mode" is information indicating the traffic transmission mode, such as Active-standby and Smallest-delay. Simultaneous transmission capability information indicates whether terminal 10 can use two "3gpp access" simultaneously.

[0041] (Step S2) The "DS-capable AM ​​node" 22_101 receives a network registration request sent from terminal 10. If the received network registration request includes information identifying other access networks or "MG-DualSteer capability", the "DS-capable AM ​​node" 22_101 saves the information identifying other access networks or "MG-DualSteer capability" included in the network registration request (Step S2a).

[0042] Alternatively, the user management node 103 of the "DS-capable C-plane" 22 ("DS-capable user management node" 22_103) may store the other access network identification information and "MG-DualSteer capability" included in the network registration request. In this case, the "DS-capable AM ​​node" 22_101 sends the other access network identification information and "MG-DualSteer capability" included in the network registration request to the "DS-capable user management node" 22_103 (step S2b-1). The "DS-capable user management node" 22_103 stores the other access network identification information and "MG-DualSteer capability" received from the "DS-capable AM ​​node" 22_101 (step S2b-2).

[0043] As a result, the "DS-capable AM ​​node" 22_101 or the "DS-capable user management node" 22_103 saves the other access network identification information and "MG-DualSteer capability" included in the network registration request of terminal 10. Alternatively, both the "DS-capable AM ​​node" 22_101 and the "DS-capable user management node" 22_103 may be configured to save the other access network identification information and "MG-DualSteer capability" included in the network registration request of terminal 10.

[0044] In addition, any conventional procedure may be performed between step S1 and step S2, or before or after them.

[0045] [Network registration information update process for MG-DualSteer] The NW registration information update process for MG-DualSteer will be explained with reference to Figure 4. Here, terminal 10 is already connected to the "DS-capable NW" 20.

[0046] (Step S11) Terminal 10 sends a network registration information update request to the "DS-capable AM ​​node" 22_101 when it establishes a connection with another "3gpp access" different from the already connected "DS-capable NW" 20. In this network registration information update request, terminal 10 includes information identifying the other access network. Note that the network registration information update request may be sent from terminal 10 at any time.

[0047] (Step S12) The "DS-capable AM ​​node" 22_101 receives a network registration information update request sent from terminal 10. If the received network registration information update request contains information identifying other access networks, the "DS-capable AM ​​node" 22_101 saves the information identifying other access networks contained in the network registration information update request (Step S12a).

[0048] The "DS-capable user management node" 22_103 may also store the other access network identification information included in the network registration information update request. In this case, the "DS-capable AM ​​node" 22_101 sends the other access network identification information included in the network registration information update request to the "DS-capable user management node" 22_103 (step S12b-1). The "DS-capable user management node" 22_103 stores the other access network identification information received from the "DS-capable AM ​​node" 22_101 (step S12b-2).

[0049] As a result, the "DS-capable AM ​​node" 22_101 or the "DS-capable user management node" 22_103 saves the other access network identification information included in the network registration information update request of terminal 10. Alternatively, both the "DS-capable AM ​​node" 22_101 and the "DS-capable user management node" 22_103 may be configured to save the other access network identification information included in the network registration information update request of terminal 10.

[0050] In addition, any conventional procedure may be performed between step S11 and step S12, or before or after them.

[0051] [Procedure for establishing an "MG-DualSteer Session"] Refer to Figure 5 to explain the "MG-DualSteer Session" establishment procedure.

[0052] (Step S21) Terminal 10 sends a session establishment request to the "DS-capable AM ​​node" 22_101. At this time, terminal 10 may include other access network identification information and "MG-DualSteer capability" in the session establishment request. Terminal 10 also sets "MG-DualSteer" as the "Request Type" to be included in the session establishment request. When the "Request Type" to be included in the session establishment request is "MG-DualSteer", it indicates that the session establishment request is a request for an "MG-DualSteer Session".

[0053] Furthermore, the session establishment request may be indicated as an "MG-DualSteer Session" request by including at least one of "other access network identification information" and "MG-DualSteer capability" in the session establishment request.

[0054] Alternatively, a new "MG-DualSteer Session" establishment request may be created as a message distinct from a normal session establishment request. The procedure for the "MG-DualSteer Session" establishment request may be the same as for a normal session establishment request.

[0055] Alternatively, the session establishment request may be indicated as an "MG-DualSteer Session" request by setting "DualSteer" as the "Request Type" to be included in the session establishment request and combining it with parameters other than "Request Type" (for example, other access network identification information or "MG-DualSteer capability").

[0056] (Step S22) The "DS-capable AM ​​node" 22_101 receives a Session establishment request sent from terminal 10 (hereinafter referred to as target terminal 10) and recognizes that the received Session establishment request is an "MG-DualSteer Session" request. If the Session establishment request from target terminal 10 includes other access network identification information and "MG-DualSteer capability", the process proceeds to step S22-3.

[0057] If the session establishment request from the target terminal 10 does not include the other access network identification information and the "MG-DualSteer capability", the "DS-capable AM ​​node" 22_101 checks whether it has stored the other access network identification information and the "MG-DualSteer capability" for the target terminal 10 (step S22-1). If, as a result of this check, the "DS-capable AM ​​node" 22_101 has stored the other access network identification information and the "MG-DualSteer capability" for the target terminal 10, the process proceeds to step S22-3.

[0058] On the other hand, if the "DS-capable AM ​​node" 22_101 does not store the other access network identification information and "MG-DualSteer capability" for the target terminal 10, it queries the "DS-capable user management node" 22_103 for the other access network identification information and "MG-DualSteer capability" for the target terminal 10, and obtains the other access network identification information and "MG-DualSteer capability" for the target terminal 10 from the "DS-capable user management node" 22_103 (step S22-2). After this, the process proceeds to step S22-3.

[0059] The "DS-capable user management node" 22_103 selects a "DS-capable SM node" 22_102 from among the SM nodes 102 ("DS-capable SM nodes" 22_102) of the "DS-capable C-plane" 22 that satisfies the MG-DualSteer requirements for the target terminal 10, based on the other access network identification information of the target terminal 10 and the "MG-DualSteer capability".

[0060] (Step S23) The "DS-capable AM ​​node" 22_101 sends a session establishment request to the selected "DS-capable SM node" 22_102, along with the other access network identification information of the target terminal 10 and the "MG-DualSteer capability". The "DS-capable SM node" 22_102 receives the session establishment request from the "DS-capable AM ​​node" 22_101, along with the other access network identification information of the target terminal 10 and the "MG-DualSteer capability".

[0061] (Step S24) The "DS-capable SM node" 22_102 compares the information of the target terminal 10 managed by the "DS-capable user management node" 22_103 with the other access network identification information of the target terminal 10 and the "MG-DualSteer capability" to determine whether the target terminal 10 can use MG-DualSteer. If the result of this determination indicates that the target terminal 10 can use MG-DualSteer, the process proceeds to step S25. On the other hand, if the target terminal 10 cannot use MG-DualSteer, the session establishment request from the target terminal 10 is rejected, and the process shown in Figure 5 is terminated.

[0062] (Step S25) The "DS-capable SM node" 22_102 sends information regarding the "MG-DualSteer capability" of the target terminal 10, as well as the "DS-capable NW" 20 and "DS-incapable NW" 30, to the policy control node 104 of the "DS-capable C-plane" 22 ("DS-capable policy control node" 22_104), and queries the MG-DualSteer rules for the target terminal 10.

[0063] The "DS-capable policy control node" 22_104 determines the MG-DualSteer rules for the target terminal 10. The MG-DualSteer rules for the target terminal 10 define how the target terminal 10 and the "DS-capable GW" 23 distribute traffic to two different generation RANs, NG-RAN21 and Legacy-RAN31. Note that the content of the MG-DualSteer rules may differ between the target terminal 10 (uplink communication) and the "DS-capable GW" 23 (downlink communication).

[0064] The "DS-capable policy control node" 22_104 responds to the "DS-capable SM node" 22_102 with the MG-DualSteer rule for the determined target terminal 10.

[0065] Alternatively, the "DS-capable policy control node" 22_104 may respond to the "DS-capable SM node" 22_102 with instructions (MG-DualSteer rule instruction information) for determining the MG-DualSteer rule for the target terminal 10, and the "DS-capable SM node" 22_102 may determine the MG-DualSteer rule for the target terminal 10 based on the said MG-DualSteer rule instruction information.

[0066] (Step S26) The "DS-capable SM node" 22_102 recognizes the "DS-incapable NW" 30 to which the target terminal 10 is currently connected or could connect, based on the other access network identification information of the target terminal 10. The "DS-capable SM node" 22_102 may also have a database that can identify the "DS-incapable NW" 30 to which the target terminal 10 is currently connected or could connect, based on the other access network identification information of the target terminal 10.

[0067] The "DS-capable SM node" 22_102 selects the "DS-capable GW" 23 from among the "DS-capable GWs" 23 at each location of the "DS-capable NW" 20 that minimizes the communication delay between the target terminals 10 via the recognized "DS-incapable NW" 30. This solves the aforementioned problem 1. Examples 1 and 2 of the method for selecting the "DS-capable GW" 23 are shown below.

[0068] <Example 1 of how to select "DS-capable GW"> If the candidate "DS-capable GW" 23 exists at both sites A and B, and "DS-incapable NW" 30 exists at site A, then the "DS-capable GW" 23 at site A is selected.

[0069] <Example 2 of how to select "DS-capable GW"> If the information specifying other access networks is provided in the list format described above, in addition to the "DS-capable GW" 23, the recommended "Legacy-RAN31 generation" is also determined. For example, suppose a 4G "DS-capable GW" 23 exists at site A, a 5G "DS-capable GW" 23 exists at site B, and a 6G "DS-capable GW" 23 exists at site C. In this case, the expected delay in communication between site C and site A is compared with the expected delay in communication between site C and site B, and the appropriate "DS-capable GW" 23 and appropriate "DS-incapable NW" 30 are selected based on the results of this comparison.

[0070] Furthermore, the "DS-capable SM node" 22_102 is configured to have the function of identifying the generation of the RAN of the "DS-incapable NW" 30 and the instance of the "DS-incapable GW" 33 from the information of the parameters when the other access network identification information is indicated by existing PLMN identifiers, RATs, cell IDs, "Access Type", or combinations thereof.

[0071] (Step S27) The "DS-capable SM node" 22_102 forwards the session establishment request received from the "DS-capable AM ​​node" 22_101 in step S23 to the selected "DS-capable GW" 23 (step S27-1). At this time, it may also send the following information (1), (2), and (3). (1) MG-DualSteer rules for "DS-capable GW" 23 obtained in step S25 (2) Other access network identification information of target terminal 10 (3) "MG-DualSteer capability" of target device 10

[0072] Based on the session establishment request received from the DS-capable SM node 22_102 and the above information (1), (2), and (3), the DS-capable GW 23 determines the IP address that can realize the optimal communication path (for example, the communication path with the lowest latency) from the DS-incapable NW 30 which is the MG-DualSteer pair of the target terminal 10 to itself, the DS-capable GW 23, and responds to the DS-capable SM node 22_102 with the determined IP address as the proxy IP address for the DS-incapable NW (step S27-2). This solves the above-mentioned problem 2.

[0073] (Step S28) The "DS-capable SM node" 22_102 responds to the "DS-capable AM ​​node" 22_101 that it has accepted the request for an "MG-DualSteer Session". In this response, the "DS-capable SM node" 22_102 sends the tunnel information necessary to establish a tunnel between the NG-RAN 21 of the "DS-capable NW" 20 and the "DS-capable GW" 23 to the "DS-capable AM ​​node" 22_101. This tunnel information is the same as before. The "DS-capable SM node" 22_102 also sends the MG-DualSteer rule for the target terminal 10 obtained in step S25, and the proxy IP address for the "DS-incapable NW" responded to from the "DS-capable GW" 23 in step S27-2 to the "DS-capable AM ​​node" 22_101. The proxy IP address for "DS-incapable NW" is the IP address that the target terminal 10 uses as the destination address for uplink communication to "DS-incapable NW" 30.

[0074] (Step S29) The "DS-capable AM ​​node" 22_101 transmits the tunnel information received in response from the "DS-capable SM node" 22_102 to the NG-RAN21.

[0075] (Step S30) The "DS-capable AM ​​node" 22_101 responds to the target terminal 10 with the MG-DualSteer rule and proxy IP address for the "DS-incapable NW" that were responded to from the "DS-capable SM node" 22_102, as well as the MG-DualSteer session establishment completion instruction information. The target terminal 10 receives the response from the "DS-capable AM ​​node" 22_101. The target terminal 10 saves the received proxy IP address for the "DS-incapable NW" to be used as the destination IP address for uplink communication of the "DS-incapable NW" 30. The target terminal 10 uses the saved proxy IP address for the "DS-incapable NW" as the destination IP address for traffic destined for the "DS-incapable NW".

[0076] According to the embodiment described above, when terminal 10 connects to two "3gpp access" systems of different generations simultaneously, an appropriate communication path can be realized.

[0077] Furthermore, this will enable improvements in overall service quality, such as in mobile communication systems, and will contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0078] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the gist of the present invention.

[0079] Alternatively, computer programs for realizing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the programs recorded on this recording medium may be loaded into a computer system and executed. The term "computer system" here may include hardware such as an operating system and peripheral devices. Furthermore, "computer-readable recording medium" refers to writable non-volatile memory such as flexible disks, magneto-optical disks, ROMs, and flash memory, portable media such as DVDs (Digital Versatile Discs), and storage devices such as hard disks built into a computer system.

[0080] Furthermore, "computer-readable recording media" also includes volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which retains the program for a certain period of time. In addition, the above program may be transmitted from the computer system that stores the program in a storage device, etc., to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line. Furthermore, the above program may be for the purpose of realizing a part of the above-mentioned functions. Moreover, it may be a so-called differential file (differential program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system. [Explanation of Symbols]

[0081] 1…Mobile communication system, 10…Terminal device, 20…DS-capable NW, 21…NG-RAN, 22…DS-capable C-plane, 23…DS-capable GW, 30…DS-incapable NW, 31…Legacy-RAN, 32…DS-incapable C-plane, 33…DS-incapable GW, 40…Data Network, 50…Remote Host, 101…AM node, 102…SM node, 103…User management node, 104…Policy control node

Claims

1. It is a mobile communication system equipped with two wireless access networks of different generations that can be connected to simultaneously by a terminal. When the aforementioned terminal requests "MG-DualSteer," which is a "DualSteer" implemented using a combination of two wireless access networks of different generations, an SM (Session Management) node selects a "DS-capable GW," which is the gateway at each location of the "DS-capable NW," capable of establishing a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that the terminal is currently connected to or could potentially connect to, that does not support "DualSteer." A mobile communication system equipped with [the following features].

2. The SM node has the function of identifying the generation of the "DS-incapable NW" wireless access network to which the terminal is connected or can connect, and the instance of the "DS-incapable GW" which is the gateway of the "DS-incapable NW", from at least one of the existing PLMN identifier, RAT, cell ID, and "Access Type" included in the other access NW identification information that can identify other wireless access networks to which the terminal is connected or can connect, other than the wireless access network to which the terminal has sent a network registration request. The mobile communication system according to claim 1.

3. The selected "DS-capable GW" determines an IP address that enables the optimal communication path from the "DS-incapable NW" that is paired with the "MG-DualSteer" of the terminal to the "DS-capable GW" itself, based on at least one of the following pieces of information: the "MG-DualSteer" rule for the "DS-capable GW", other access network identification information that can identify other wireless access networks that the terminal is connected to or can connect to other than the wireless access network from which the terminal sent a network registration request, and "MG-DualSteer capability" indicating that the terminal supports "MG-DualSteer". The determined IP address will be used as the proxy IP address for "DS-incapable NW". The mobile communication system according to claim 1.

4. The SM node includes a database that can identify a "DS-incapable NW" to which the terminal is connected or can connect, from other access network identification information that can identify other wireless access networks to which the terminal is connected or can connect, other than the wireless access network to which the terminal sent a network registration request. The mobile communication system according to claim 1.

5. The terminal includes in its network registration request other access network identification information that allows it to identify other wireless access networks that it is currently connected to or can connect to, other than the wireless access network from which it sent the network registration request. A mobile communication system according to any one of claims 1 to 4.

6. The terminal includes in the network registration information update request other access network identification information that can identify other wireless access networks that it is currently connected to or can connect to, other than the wireless access network from which it sent the network registration request. A mobile communication system according to any one of claims 1 to 4.

7. The terminal includes in its session establishment request other access network identification information that allows it to identify other wireless access networks that it is currently connected to or can connect to, other than the wireless access network from which it sent the network registration request. A mobile communication system according to any one of claims 1 to 4.

8. The terminal sets the "Request Type" of the session establishment request to "MG-DualSteer". The mobile communication system according to claim 7.

9. The aforementioned terminal manages the proxy IP address for "DS-incapable NW" as the IP address for uplink communication of "DS-incapable NW", and uses the said proxy IP address for "DS-incapable NW" as the destination IP address for traffic destined for "DS-incapable NW". A mobile communication system according to any one of claims 1 to 4.

10. The system further includes a node that manages other access network identification information capable of identifying other wireless access networks that are connected to or can be connected to, other than the wireless access network from which the terminal sent the network registration request. A mobile communication system according to any one of claims 1 to 4.

11. A network device for a mobile communication system that has two wireless access networks of different generations to which terminals can connect simultaneously. When the terminal requests "MG-DualSteer," which is a "DualSteer" implemented using a combination of two wireless access networks of different generations, the system selects a "DS-capable GW," which is the gateway at each location of the "DS-capable NW," that can establish a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that the terminal is currently connected to or could potentially connect to that does not support "DualSteer." Network device.

12. The terminal device is a mobile communication system comprising two wireless access networks of different generations to which the terminal device can connect simultaneously. The network registration request includes information that identifies other wireless access networks that the terminal is currently connected to or could potentially connect to, in addition to the wireless access network from which it sent the network registration request. Terminal device.

13. This is a communication method performed by a mobile communication system that has two wireless access networks of different generations to which terminals can connect simultaneously. When the terminal requests "MG-DualSteer," which is a "DualSteer" implemented using a combination of two wireless access networks of different generations, the system selects a "DS-capable GW," which is the gateway at each location of the "DS-capable NW," that can establish a session using a "DS-capable NW," which is a mobile core network that supports "DualSteer," and a "DS-incapable NW," which is a mobile core network that the terminal is currently connected to or could potentially connect to that does not support "DualSteer." Communication method.

14. A computer in a mobile communication system equipped with two wireless access networks of different generations that a terminal can connect to simultaneously, When the terminal requests "MG-DualSteer," which is a "DualSteer" implemented using a combination of two wireless access networks of different generations, the step is to select a "DS-capable GW," which is a gateway at each location of the "DS-capable NW," a mobile core network that supports "DualSteer," and a "DS-incapable NW," a mobile core network that does not support "DualSteer," to which the terminal is currently connected or could potentially connect. A computer program designed to execute something.

Images