Communication system, communication method, and program

Abstract

A communication system is realized that allows mobile terminals to communicate smoothly with a plurality of mobile communication systems. [Solution] The communication system includes a first gateway unit that stores mobile terminals in association with IP addresses, and the second mobile communication system includes a second gateway unit that stores mobile terminals in association with IP addresses, and the first gateway unit and the second gateway unit store the same IP address in association with the same mobile terminal, and the first gateway unit sends the packet to the second gateway unit if the destination IP address of a received packet is not stored in association with the mobile terminal.

Description

[Technical Field]

[0001] The present disclosure relates to a communication system, a communication method, and a program. [Background technology]

[0002] There are known techniques for configuring a terminal (mobile terminal) to connect to multiple mobile communication systems. For example, Patent Document 1 discloses a communication system in which an address that can be used even if the mobile communication carrier network changes is assigned to the terminal, and the terminal connects to the mobile communication carrier network using the assigned address. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-161336 Summary of the Invention [Problem to be solved by the invention]

[0004] In the communication system described in Patent Document 1, a terminal needs to switch addresses when it changes the mobile communication carrier network it connects to. Therefore, in the communication system described in Patent Document 1, a terminal cannot continue communication when it changes the mobile communication carrier network it connects to. In other words, the communication system described in Patent Document 1 has a problem in that it cannot communicate smoothly.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and one exemplary purpose thereof is to provide a technology that enables a mobile terminal to communicate smoothly with a plurality of mobile communication systems. [Means for solving the problem]

[0006] A communication system according to an exemplary aspect of the present disclosure is a communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, wherein the first mobile communication system is provided with a first gateway means that communicates with an external device of the first mobile communication system and associates and stores an IP address of a mobile terminal connected to the first mobile communication system, and the second mobile communication system is provided with a second gateway means that communicates with an external device of the second mobile communication system and associates and stores an IP address of the mobile terminal, wherein the first gateway means and the second gateway means each associate and store the same IP address with the same mobile terminal, and when the destination IP address of a packet received from the external device has not been stored in association with the mobile terminal, the first gateway means transmits the packet to the second gateway means.

[0007] A communication method according to an exemplary aspect of the present disclosure is executed by a communication system including a first mobile communication system that communicates with an external device and a second mobile communication system different from the first mobile communication system, the communication method including the second mobile communication system that communicates with the external device, the communication method including: a first storage process that associates and stores a mobile terminal connected to the first mobile communication system with an IP address of the mobile terminal; and a second storage process that associates and stores a mobile terminal connected to the second mobile communication system with an IP address of the mobile terminal, wherein the first storage process and the second storage process associate and store the same IP address with the same mobile terminal, and the communication method further includes a transmission process that transmits the packet to the second mobile communication system if the destination IP address of a packet received by the first mobile communication system from the external device has not been stored in the first storage process in association with the mobile terminal.

[0008] A program according to an exemplary aspect of the present disclosure causes a computer to function as a communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, the program causing the computer to function as a first gateway means that communicates with a device external to the first mobile communication system and stores a mobile terminal connected to the first mobile communication system in association with the IP address of the mobile terminal, and a second gateway means that communicates with a device external to the second mobile communication system and stores a mobile terminal connected to the second mobile communication system in association with the IP address of the mobile terminal, the first gateway means and the second gateway means each store the same IP address in association with the same mobile terminal, and the first gateway means transmits the packet to the second gateway means when the destination IP address of a packet received from the external device is not stored in association with the mobile terminal. [Effects of the Invention]

[0009] According to an exemplary aspect of the present disclosure, an exemplary effect is achieved in that a technology is provided that enables a mobile terminal to communicate smoothly with a plurality of mobile communication systems. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram illustrating a configuration of a communication system according to the present disclosure. [Figure 2] FIG. 1 is a flow diagram illustrating a communication method according to the present disclosure. [Figure 3] 1 is a block diagram illustrating a configuration of a communication system according to the present disclosure. [Figure 4] 10 is a flow diagram showing a process flow for assigning an IP address to a UE according to the present disclosure. [Figure 5] 3A to 3C are diagrams illustrating examples of tables according to the present disclosure. [Figure 6] FIG. 1 is a flow diagram showing a flow of processing executed in a communication system according to the present disclosure. [Figure 7] 1 is a block diagram illustrating a configuration of a communication system according to the present disclosure. [Figure 8] FIG. 1 is a flow diagram showing a flow of processing executed in a communication system according to the present disclosure. [Figure 9] 1 is a block diagram showing the configuration of a computer that functions as part or all of a first mobile communication system, a second mobile communication system, a UPF, and a PGW according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following are examples of embodiments of the present invention. However, the present invention is not limited to the exemplary embodiments shown below, and various modifications are possible within the scope of the claims. For example, embodiments obtained by appropriately combining the technologies (part or all of the products or methods) employed in the exemplary embodiments shown below may also be included in the scope of the present invention. Furthermore, embodiments obtained by appropriately omitting some of the technologies employed in the exemplary embodiments shown below may also be included in the scope of the present invention. Furthermore, the effects mentioned in the exemplary embodiments shown below are examples of effects expected in the exemplary embodiments, and do not define the scope of the present invention. In other words, embodiments that do not exhibit the effects mentioned in the exemplary embodiments shown below may also be included in the scope of the present invention.

[0012] First Exemplary Embodiment A first exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. This exemplary embodiment is a basic form for each of the exemplary embodiments described below. The scope of application of each technology employed in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology employed in this exemplary embodiment can also be employed in other exemplary embodiments included in the present disclosure, to the extent that no particular technical obstacles arise. Furthermore, each technology shown in the drawings referenced to explain this exemplary embodiment can also be employed in other exemplary embodiments included in the present disclosure, to the extent that no particular technical obstacles arise.

[0013] (Configuration of communication system 1) The configuration of communication system 1 will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of communication system 1. As shown in Fig. 1, communication system 1 includes a first mobile communication system 11 and a second mobile communication system 21 that is different from first mobile communication system 11.

[0014] (First mobile communication system 11) As shown in Fig. 1, the first mobile communication system 11 includes a first gateway unit 111. The first gateway unit 111 realizes a first gateway means in this exemplary embodiment.

[0015] The first gateway unit 111 communicates with devices external to the first mobile communication system 11. The first gateway unit 111 also stores a mobile terminal connected to the first mobile communication system 11 in association with the IP address of the mobile terminal.

[0016] Furthermore, if the destination IP address of a packet received from an external device is not stored in association with a mobile terminal, the first gateway unit 111 transmits the packet to the second gateway unit 211, which will be described later.

[0017] (Second mobile communication system 21) As shown in Fig. 1, the second mobile communication system 21 includes a second gateway unit 211. The second gateway unit 211 realizes a second gateway means in this exemplary embodiment.

[0018] The second gateway unit 211 communicates with devices external to the second mobile communication system 21. The second gateway unit 211 also stores a mobile terminal connected to the second mobile communication system 21 in association with the IP address of the mobile terminal.

[0019] Furthermore, the first gateway unit 111 and the second gateway unit 211 each store the same IP address in association with the same mobile terminal.

[0020] (Effects of Communication System 1) As described above, the communication system 1 includes the first mobile communication system 11 and the second mobile communication system 21 which is different from the first mobile communication system 11.

[0021] In addition, the first mobile communication system 11 is provided with a first gateway unit 111 that communicates with devices external to the first mobile communication system 11 and associates and stores the IP addresses of mobile terminals connected to the first mobile communication system 11.

[0022] In addition, the second mobile communication system 21 is provided with a second gateway unit 211 that communicates with devices external to the second mobile communication system 21 and stores a mobile terminal connected to the second mobile communication system 21 in association with the IP address of the mobile terminal.

[0023] In addition, the first gateway unit 111 and the second gateway unit 211 each associate and store the same IP address with the same mobile terminal, and if the destination IP address of a packet received from an external device is not stored in association with the mobile terminal, the first gateway unit 111 transmits the packet to the second gateway unit 211.

[0024] Therefore, according to communication system 1, the IP address of a mobile terminal does not change whether the mobile terminal is connected to first mobile communication system 11 or second mobile communication system 21. Furthermore, when the mobile terminal is connected to first mobile communication system 11, packets received by first mobile communication system 11 from an external device are transmitted to the mobile terminal. On the other hand, when the mobile terminal is connected to second mobile communication system 21, packets received by first mobile communication system 11 from an external device are transmitted to second mobile communication system 21, and then transmitted to the mobile terminal in second mobile communication system 21.

[0025] Therefore, the communication system 1 allows mobile terminals to communicate smoothly with a plurality of mobile communication systems.

[0026] (Example of program implementation) When the communication system 1 is configured by a computer including at least one processor and a memory, the following programs are stored in the memory. The program causes a computer to function as a communication system 1 including a first mobile communication system 11 and a second mobile communication system 21 different from the first mobile communication system 11, and causes the computer to function as a first gateway unit 111 that communicates with a device external to the first mobile communication system 11 and stores a mobile terminal connected to the first mobile communication system 11 in association with the IP address of the mobile terminal, and a second gateway unit 211 that communicates with a device external to the second mobile communication system 21 and stores a mobile terminal connected to the second mobile communication system 21 in association with the IP address of the mobile terminal, and the first gateway unit 111 and the second gateway unit 211 each store the same IP address in association with the same mobile terminal, and if the destination IP address of a packet received from an external device is not stored in association with the mobile terminal, the first gateway unit 111 sends the packet to the second gateway unit 211.

[0027] (Communication method St1 flow) The flow of a communication method St1 executed by a communication system 1 including a first mobile communication system 11 that communicates with an external device and a second mobile communication system 21 that is different from the first mobile communication system 11 and that communicates with the external device will be described with reference to Fig. 2. Fig. 2 is a flow diagram showing the flow of the communication method St1. As shown in Fig. 2, the communication method St1 includes a storage process St11 and a transmission process St12.

[0028] (Amnestic Treatment St11) As shown in FIG. 2, the storage process St11 includes a first storage process St111 and a second storage process St112.

[0029] In the first storage process St111, the first mobile communication system 11 stores the mobile terminal connected to the first mobile communication system 11 in association with the IP address of the mobile terminal.

[0030] In the second storage process St112, the second mobile communication system 21 stores the mobile terminal connected to the second mobile communication system 21 in association with the IP address of the mobile terminal.

[0031] In the storage process St11, the same IP address is stored in association with the same mobile terminal in the first storage process St111 and the second storage process St112.

[0032] (Transmission process St12) In the transmission process St12, if the destination IP address of the packet received by the first mobile communication system 11 from an external device is not stored in the first storage process St111 in association with the mobile terminal, the first mobile communication system 11 transmits the packet to the second mobile communication system 21.

[0033] (Effect of communication method St1) As described above, the communication method St1 is executed by a communication system 1 including a first mobile communication system 11 that communicates with an external device and a second mobile communication system 21 that is different from the first mobile communication system 11 and that communicates with an external device.

[0034] In addition, in the communication method St1, the first mobile communication system 11 includes a first storage process St111 in which a mobile terminal connected to the first mobile communication system 11 is associated with and stores the IP address of the mobile terminal, and the second mobile communication system 21 includes a second storage process St112 in which a mobile terminal connected to the second mobile communication system 21 is associated with and stores the IP address of the mobile terminal, and in the first storage process St111 and the second storage process St112, the same IP address is associated with and stored for the same mobile terminal.

[0035] In addition, the communication method St includes a transmission process St12 in which, if the destination IP address of a packet received by the first mobile communication system 11 from an external device is not stored in association with a mobile terminal in the first storage process St111, the packet is transmitted to the second mobile communication system 21.

[0036] Therefore, the communication method St1 provides the same effects as the communication system 1 described above.

[0037] Second Exemplary Embodiment A second exemplary embodiment, which is one example of an embodiment of the present invention, will be described in detail with reference to the drawings. Components having the same functions as those described in the above exemplary embodiment will be assigned the same reference numerals, and their description will be omitted as appropriate. The scope of application of each technology employed in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology employed in this exemplary embodiment can also be employed in other exemplary embodiments included in the present disclosure, to the extent that no particular technical hindrance occurs. Furthermore, each technology shown in each drawing referenced to explain this exemplary embodiment can also be employed in other exemplary embodiments included in the present disclosure, to the extent that no particular technical hindrance occurs.

[0038] (Overview and Configuration of Communication System 1A) The overview and configuration of the communication system 1A will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the configuration of the communication system 1A.

[0039] The communication system 1A is a system including a plurality of mobile communication systems. In the present disclosure, as an example, a case where the communication system 1A includes a first mobile communication system 11A and a second mobile communication system 21A as shown in Fig. 3 will be described, but the number of mobile communication systems included in the communication system 1A is not particularly limited.

[0040] The first mobile communication system 11A and the second mobile communication system 21A are not particularly limited, but as an example, one of the first mobile communication system 11A and the second mobile communication system 21A is an sXGP (shared eXtended Global Platform) system, and the other is a local 5G system (5th Generation Mobile Communication System).

[0041] With this configuration, the communication system 1A can be applied to a communication system that includes multiple mobile communication systems with different characteristics, such as sXGP, which can be constructed more cheaply, and local 5G, which is faster, has lower latency, and is wider area.

[0042] In this disclosure, a case will be described in which the first mobile communication system 11A is a local 5G system and the second mobile communication system 21A is sXGP.

[0043] In the communication system 1A, a mobile terminal (UE: User Equipment) 30 connects to the first mobile communication system 11A and the second mobile communication system 21A using one IP address. That is, in the communication system 1A, the UE 30 can connect to both the first mobile communication system 11A and the second mobile communication system 21A without changing the IP address.

[0044] In addition, in the communication system 1A, at least one of the first mobile communication system 11A and the second mobile communication system 21A is configured to be able to transmit and receive data (packets) to and from a data network DN (Data Network) external to the communication system 1A. In this exemplary embodiment, a case will be described in which the first mobile communication system 11A is able to communicate with the data network DN, as shown in FIG.

[0045] (Configuration of the first mobile communication system 11A) The configuration of the first mobile communication system 11A will be described again with reference to Fig. 3. As described above, the first mobile communication system 11A is a local 5G system and includes NFs (Network Functions) required for the network. Details of each NF will be described.

[0046] The UPF (User Plane Function) 111 is a component that realizes a first gateway means in this exemplary embodiment, and communicates with a device (data network DN) external to the first mobile communication system 11A. As an example, the UPF 111 receives packets from the data network DN and transmits packets to the data network DN. The UPF 111 and the data network DN transmit and receive packets via an interface called N6.

[0047] Furthermore, upon receiving a registration request from the UE 30, the UPF 111 establishes a PDU (Protocol Data Unit) session between the UE 30 and the UPF 111. The UPF 111 associates a PDU session ID, which is an identifier of the PDU session, with the IP address of the UE 30 and stores the associated PDU session ID. The IP address of the UE 30 is associated with the IMSI (International Mobile Subscription Identity) of the UE 30 in an IMSI table, which will be described later. Therefore, the association of the PDU session ID with the IP address of the UE 30 by the UPF 111 means that the UPF 111 associates the UE 30 with the IP address of the UE 30.

[0048] 3, the UPF 111 also includes a registration unit 112. The registration unit 112 associates the same IP address with the same UE 30 as an IP address for connecting to the second mobile communication system 21A, which will be described later, and stores the IP address. As an example, the registration unit 112 associates the same IP address with the same UE 30 and stores the IP address in a storage unit not shown in FIG. 3. As an example, the registration unit 112 generates a PDU session table that associates a PDU session ID with the IP address of the UE 30. With this configuration, the registration unit 112 can manage the IP addresses of the UEs 30 connected to the first mobile communication system 11A.

[0049] The UPF 111 also stores the IP address of a Packet Data Network Gateway (PGW) 211, which will be described later. As an example, the UPF 111 stores the IP address of the PGW 211 in a storage unit not shown in Fig. 3. With this configuration, when transmitting a packet to the PGW 211, the UPF 111 can transmit the packet to the PGW 211 by referencing the stored IP address.

[0050] An example of the processing executed by the UPF 111 and the registration unit 112 will be described later.

[0051] The gNB (next generation Node B) 121 is a base station in a local 5G system. The gNB 121 and the UPF 111 transmit and receive data via an interface called N3.

[0052] An access and mobility management function (AMF) 122 performs registration management, connection management, and mobility management for UE 30. The AMF 122 and UE 30 transmit and receive data via an interface called N1. The AMF 122 and gNB 121 transmit and receive data via an interface called N2.

[0053] The SMF (Session Management Function) 123 manages sessions between the UPF 111 and the RAN (Radio Access Network). The SMF 123 also performs tasks such as allocating IP addresses to the UE 30 and setting traffic routing to the UPF 111. The SMF 123 and the UPF 111 transmit and receive data via an interface called N4. The SMF 123 and the AMF 122 transmit and receive data via an interface called N11.

[0054] A PCF (Policy Control Function) 124 performs policy control. The PCF 124 and the SMF 123 transmit and receive data via an interface called N7.

[0055] The AF (Application Function) 125 executes auxiliary services. The AF 125 and the PCF 124 transmit and receive data via an interface called N5.

[0056] A Network Slice Selection Function (NSSF) 126 selects a network slice to be used by the UE 30. The NSSF 126 and the AMF 122 transmit and receive data via an interface called N22.

[0057] An AUSF (Authentication Server Function) 127 performs authentication. The AUSF 127 and the AMF 122 transmit and receive data via an interface called N12.

[0058] The UDM (Unified Data Management) 128 manages contract information and authentication information of the UE 30. As an example, the UDM 128 stores an IMSI table, which associates the IMSI of a SIM (Subscriber Identity Module) mounted on the UE 30 with the IP address of the UE 30, in a storage unit (not shown in FIG. 3). The IMSI table may be stored in advance in the storage unit of the UDM 128 by an administrator of the communication system 1A. An example of the IMSI table will be described later. The UDM 128 and the AMF 122 transmit and receive data via an interface called N8. The UDM 128 and the SMF 123 transmit and receive data via an interface called N10. The UDM 128 and the AUSF 127 transmit and receive data via an interface called N13.

[0059] (Configuration of second mobile communication system 21A) The configuration of the second mobile communication system 21A will be described with reference to Figure 3 again. As described above, the second mobile communication system 21A is an sXGP system, and is equipped with the components necessary for a network. Each component will be described in detail.

[0060] The PGW 211 is configured to realize a second gateway means in this exemplary embodiment, and communicates with a device (UPF 111) external to the second mobile communication system 21A. In other words, as shown in Fig. 3, the PGW 211 transmits and receives data to and from the data network DN via the UPF 111. As an example, the PGW 211 receives packets from and transmits packets to the UPF 111. The PGW 211 and the UPF 111 transmit and receive packets via an interface called SGi.

[0061] Furthermore, upon receiving an attach request from UE 30, PGW 211 establishes a PDN (Packet Data Network) connection between UE 30 and PGW 211. Furthermore, PGW 211 associates a PDN connection ID, which is an identifier of the PDN connection, with the IP address of UE 30 and stores the association. The IP address of UE 30 is associated with the IMSI of UE 30 in an IMSI table, which will be described later. Therefore, when PGW 211 associates the PDN connection ID with the IP address of UE 30, this means that PGW 211 associates the UE 30 with the IP address of UE 30.

[0062] 3, the PGW 211 also includes a registration unit 212. The registration unit 212 associates the same IP address as the IP address for connecting to the first mobile communication system 11A with the same UE 30 and stores the IP address. As an example, the registration unit 212 associates the same IP address with the same UE 30 and stores the IP address in a storage unit not shown in FIG. 3. As an example, the registration unit 212 generates a PDN connection table that associates a PDN connection ID with the IP address of the UE 30. With this configuration, the registration unit 212 can manage the IP addresses of the UEs 30 connected to the second mobile communication system 21A.

[0063] An example of the processing executed by the PGW 211 will be described later.

[0064] The eNB (evolved Node B) 221 is a base station in the sXGP system.

[0065] The SGW (Serving Gateway) 222 transfers user packets between the RAN and the core network. The eNB 221 and the SGW 222 transmit and receive data via an interface called S1. The SGW 222 and the PGW 211 transmit and receive data via an interface called S5.

[0066] An MME (Mobility Management Entity) 223 processes a NAS (Non Access Stratum) signal for mobility management and session management (bearer control) of the UE 30. The MME 223 and the SGW 222 transmit and receive data via an interface called S11.

[0067] The HSS (Home Subscriber Server) 224 is a database that holds location information, service subscription information, and authentication information of the UE 30. As an example, the HSS 224 stores an IMSI table, which associates the IMSI of the SIM installed in the UE 30 with the IP address of the UE 30, in a storage unit not shown in FIG. 3. The IMSI table may be stored in advance in the storage unit of the HSS 224 by an administrator of the communication system 1A. The HSS 224 and the MME 223 transmit and receive data via an interface called S6a.

[0068] The PCRF (Policy and Charging Rules Function) 225 controls the quality of service (Qos) of user data transfer and charging. The PCRF 225 and the SGW 222 transmit and receive data via an interface called Gxc. The PCRF 225 and the PGW 211 transmit and receive data via an interface called Gx.

[0069] (IP address allocation process) The process of assigning an IP address to the UE 30 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the flow of the process of assigning an IP address to the UE 30.

[0070] First, a process flow for allocating an IP address when the UE 30 connects to the first mobile communication system 11A will be described.

[0071] (Step S11A) In step S11A, the UE 30 makes a registration request to the UPF 111 of the first mobile communication system 11A via the gNB 121. Here, the UE 30 transmits the IMSI of the SIM installed in the UE 30 to the UPF 111.

[0072] (Step S12A) In step S12A, upon receiving the registration request from UE 30, UPF 111 issues a PDU session ID. Next, registration unit 112 of UPF 111 associates the IP address associated with the IMSI transmitted from UE 30 with the PDU session ID in the IMSI table stored in the storage unit of UDM 128. That is, in step S12A, UPF 111 associates the IP address with UE 30 and stores it.

[0073] An example of the process executed in step S12A will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of each table.

[0074] For example, a case will be described in which UPF 111 accepts a registration request from UE 30 in step S12A, issues PDU session ID "1," and receives IMSI "440990000000001" from UE 30. In this case, registration unit 112 extracts IP address "192.168.0.1" associated with IMSI "440990000000001" from the IMSI table (the IMSI table shown in the lower left of FIG. 5) stored in the storage unit of UDM 128. Then, registration unit 112 associates PDU session ID "1" with IP address "192.168.0.1," and stores them in the PDU session table (the PDU session table shown in the upper left of FIG. 5).

[0075] When UE30 terminates its connection with the first mobile communication system 11A (for example, when UE30 moves out of the range of the first mobile communication system 11A), UPF111 deletes the PDU session ID of the UE30 from the PDU session table and also deletes the IP address associated with the PDU session ID.

[0076] Next, a process flow for allocating an IP address when the UE 30 connects to the second mobile communication system 21A will be described.

[0077] (Step S13A) In step S13A, the UE 30 makes an attach request to the PGW 211 of the second mobile communication system 21A via the eNB 221 and the SGW 222. Here, the UE 30 transmits to the PGW 211 the IMSI of the SIM installed in the UE 30.

[0078] (Step S14A) In step S14A, upon receiving the attach request from UE 30, PGW 211 issues a PDN connection ID. Next, registration unit 212 of PGW 211 associates the IP address associated with the IMSI transmitted from UE 30 with the PDN connection ID in the IMSI table stored in the storage unit of HSS 224. That is, in step S14A, PGW 211 associates the IP address with UE 30 and stores it.

[0079] An example of the process executed in step S14A will be described with reference again to FIG.

[0080] For example, a case will be described in which the PGW 211 accepts an attach request from the UE 30 in step S14A, issues a PDN connection ID "1," and receives an IMSI "440990000000003" from the UE 30. In this case, the registration unit 212 extracts the IP address "192.168.0.3" associated with the IMSI "440990000000003" from the IMSI table (the IMSI table shown in the lower right of FIG. 5) stored in the storage unit of the HSS 224. Then, the registration unit 112 associates the PDN connection ID "1" with the IP address "192.168.0.3," and stores them in the PDN connection table (the PDN connection table shown in the upper right of FIG. 5).

[0081] When UE30 terminates the connection with the second mobile communication system 21A (for example, when UE30 moves out of the range of the second mobile communication system 21A), PGW211 deletes the PDN connection ID of UE30 from the PDN connection table and also deletes the IP address associated with the PDN connection ID.

[0082] As another example, a case will be described in which the PGW 211 accepts an attach request from the UE 30 in step S14A, issues a PDN connection ID "3," and, similar to the example of step S12A, receives an IMSI "440990000000001" from the UE 30. In this case as well, the registration unit 212 extracts the IP address "192.168.0.1" associated with the IMSI "440990000000001" from the IMSI table stored in the storage unit of the HSS 224. Then, the registration unit 212 associates the PDN connection ID "3" with the IP address "192.168.0.1" and stores them in the PDN connection table.

[0083] In this way, the IP address assigned to the UE 30 with the IMSI "440990000000001" is the same "192.168.0.1" in both the first mobile communication system 11A and the second mobile communication system 21A.

[0084] (When UE30 has two SIMs) As yet another example, a case will be described in which two SIMs (a first SIM and a second SIM) are installed in the UE 30. In this example, the UE 30 communicates with the first mobile communication system 11A using the installed first SIM, and communicates with the second mobile communication system 21A using the installed second SIM that is different from the first SIM.

[0085] In this case as well, in step S12A, UPF 111 accepts a registration request from UE 30, issues PDU session ID "10," and receives the IMSI "440990000000010" of the first SIM from UE 30. Similarly in this case, registration unit 112 extracts IP address "192.168.0.10" associated with IMSI "440990000000010" from the IMSI table stored in the storage unit of UDM 128. Then, registration unit 112 associates PDU session ID "10" with IP address "192.168.0.10" and stores them in the PDU session table. That is, UPF 111 associates the IMSI, which is the identifier of the first SIM, with the IP address of UE 30 and stores them.

[0086] Next, in step S14A, the PGW 211 accepts an attach request from the UE 30, issues a PDN connection ID "11," and receives the IMSI "440990000000011" of the second SIM from the UE 30. In this case, the registration unit 212 similarly extracts the IP address "192.168.0.10" associated with the IMSI "440990000000011" from the IMSI table stored in the storage unit of the HSS 224. The registration unit 212 then associates the PDN connection ID "11" with the IP address "192.168.0.10" and stores them in the PDN connection table. That is, the PGW 211 associates the IMSI, which is the identifier of the second SIM, with the IP address of the UE 30 and stores them.

[0087] In this way, even if the SIMs used in the first mobile communication system 11A and the second mobile communication system 21A are different for each system, the same IP address is assigned to the same UE 30.

[0088] With this configuration, even if UE 30 is equipped with multiple SIMs and communicates with each of the multiple mobile communication systems using different SIMs, the communication system 1A can assign the same IP address in each of the multiple mobile communication systems.

[0089] (Flow of processing executed in communication system 1A) The flow of the process S2A executed in the communication system 1A will be described with reference to Fig. 6. Fig. 6 is a flow diagram showing the flow of the process S2A executed in the communication system 1A.

[0090] (Step S21A) In step S21A, the UPF 111 of the first mobile communication system 11A receives a packet having a destination IP address of UE 30 from the data network DN.

[0091] (Step S22A) In step S22A, the UPF 111 determines whether the destination IP address of the packet is stored in the PDU session table. In other words, the UPF 111 determines whether a UE 30 assigned the same IP address as the destination IP address of the packet is connected to the first mobile communication system 11A.

[0092] (Step S23A) If, in step S22A, it is determined that the destination IP address of the packet is stored in the PDU session table (step S22A: YES), in step S23A, UPF111 transmits the packet received in step S21A via gNB121 to UE30 assigned the same IP address as the destination IP address.

[0093] (Step S24A) In step S24A, UE 30 receives the packet transmitted in step S23A.

[0094] (Step S25A) On the other hand, if it is determined in step S22A that the destination IP address of the packet is not stored in the PDU session table (step S22A: NO), the UPF 111 transmits the packet received in step S21A to the PGW 211 in step S25A.

[0095] (Step S26A) In step S26A, the PGW 211 of the second mobile communication system 21A receives the packet transmitted in step S25A.

[0096] (Step S27A) In step S27A, the PGW 211 determines whether the destination IP address of the packet is stored in the PDN connection table. In other words, the PGW 211 determines whether a UE 30 to which the same IP address as the destination IP address of the packet is assigned is connected to the second mobile communication system 21A.

[0097] (Step S28A) If it is determined in step S27A that the destination IP address of the packet is stored in the PDN connection table (step S27A: YES), in step S28A, the PGW211 transmits the packet received in step S26A to the UE30 assigned the same IP address as the destination IP address via the SGW222 and the eNB221.

[0098] (Step S29A) In step S29A, UE 30 receives the packet transmitted in step S28A.

[0099] (Step S30A) On the other hand, if it is determined in step S27A that the destination IP address of the packet is not stored in the PDN connection table (step S27A: NO), in step S30A, the PGW 211 discards the packet received in step S26A.

[0100] (Processing by UE30 to send packets) The process of UE 30 transmitting a packet will be described.

[0101] When the UE 30 is connected to the first mobile communication system 11A, the packet transmitted from the UE 30 is received by the UPF 111. Then, the UPF 111 transmits the packet to the data network DN.

[0102] On the other hand, when the UE 30 is connected to the second mobile communication system 21A, the packet transmitted from the UE 30 is received by the PGW 211. The PGW 211 transmits the received packet to the UPF 111 of the first mobile communication system 11A. Then, the UPF 111 transmits the received packet to the data network DN.

[0103] (Effects of Communication System 1A) As described above, in the communication system 1A, the same IP address is assigned to the UE 30 in both the first mobile communication system 11A connected to the data network DN and the second mobile communication system 21A. When the UE 30 is connected to the first mobile communication system 11A, packets addressed to the UE 30 are transmitted from the UPF 111 to the UE 30. On the other hand, when the UE 30 is connected to the second mobile communication system 21A, packets addressed to the UE 30 are transmitted from the UPF 111 to the PGW 211 and then transmitted from the PGW 211 to the UE 30.

[0104] Therefore, in the communication system 1A, whether the UE 30 is connected to the first mobile communication system 11A or the second mobile communication system 21A, the UE 30 can communicate smoothly with either mobile communication system without changing its IP address.

[0105] Furthermore, in the communication system 1A, the PGW 211 is not directly connected to the data network DN. That is, in the communication system 1A, only one of the multiple mobile communication systems is directly connected to the data network DN. Even in this configuration, in the communication system 1A, the UE 30 can communicate with the data network DN regardless of which mobile communication system it is connected to.

[0106] Third Exemplary Embodiment A third exemplary embodiment, which is an example of an embodiment of the present invention, will be described in detail with reference to the drawings. Components having the same functions as those described in the above exemplary embodiment will be assigned the same reference numerals, and their description will be omitted as appropriate. The scope of application of each technology employed in this exemplary embodiment is not limited to this exemplary embodiment. That is, each technology employed in this exemplary embodiment can also be employed in other exemplary embodiments included in the present disclosure, to the extent that no particular technical obstacles arise. Furthermore, each technology shown in each drawing referenced to explain this exemplary embodiment can also be employed in other exemplary embodiments included in the present disclosure, to the extent that no particular technical obstacles arise.

[0107] (Overview and configuration of communication system 1B) The overview and configuration of the communication system 1B will be described with reference to Fig. 7. Fig. 7 is a block diagram showing the configuration of the communication system 1B.

[0108] The communication system 1B is a system including a plurality of mobile communication systems, similar to the above-described communication system 1A. In the present disclosure, as an example, a case will be described in which the communication system 1B includes a first mobile communication system 11B and a second mobile communication system 21B, as shown in FIG.

[0109] Furthermore, in the communication system 1B, similarly to the above-described communication system 1A, the UE 30 connects to the first mobile communication system 11B and the second mobile communication system 21B using one IP address. That is, in the communication system 1B, the UE 30 can connect to both the first mobile communication system 11B and the second mobile communication system 21B without changing the IP address.

[0110] In addition, in the communication system 1B, at least one of the first mobile communication system 11B and the second mobile communication system 21B is configured to be able to transmit and receive data to and from a data network DN external to the communication system 1B. In this exemplary embodiment, as shown in Fig. 7, a case will be described in which the second mobile communication system 21A is able to communicate with the data network DN.

[0111] (Configuration of the first mobile communication system 11B) The configuration of the first mobile communication system 11B will be described again with reference to Fig. 7. As shown in Fig. 7, the first mobile communication system 11B includes each NF, similar to the first mobile communication system 11A. Of the NFs included in the first mobile communication system 11B, the NFs other than the UPF 111 are as described above.

[0112] The UPF 111 is configured to realize a second gateway means in this exemplary embodiment, and communicates with a device (PGW 211) external to the first mobile communication system 11A. In other words, as shown in FIG. 7, the UPF 111 transmits and receives data to and from the data network DN via the PGW 211. The UPF 111 does not directly communicate with the data network DN. As an example, the UPF 111 receives packets from and transmits packets to the PGW 211. The PGW 211 and the UPF 111 transmit and receive packets via an interface called SGi.

[0113] The process in which the UPF 111 accepts a registration request from the UE 30 and establishes a PDU session, and the process executed by the registration unit 112 are the same as the processes described above, and therefore description thereof will be omitted.

[0114] (Configuration of second mobile communication system 21B) The configuration of the second mobile communication system 21B will be described again with reference to Fig. 7. As shown in Fig. 7, the second mobile communication system 21B includes the same components as the second mobile communication system 21A. Of the components included in the second mobile communication system 21B, the components other than the PGW 211 are as described above.

[0115] The PGW 211 is a configuration that realizes a first gateway means in this exemplary embodiment, and communicates with a device (data network DN) external to the second mobile communication system 21B. As an example, the PGW 211 receives packets from the data network DN and transmits packets to the data network DN.

[0116] The process in which the PGW 211 receives an attach request from the UE 30 and establishes a PDN connection, and the process executed by the registration unit 212 are the same as those described above, and therefore description thereof will be omitted.

[0117] (Flow of processing executed in communication system 1B) The flow of the process S2B executed in the communication system 1B will be described with reference to Fig. 8. Fig. 8 is a flow diagram showing the flow of the process S2B executed in the communication system 1B.

[0118] (Step S21B) In step S21B, the PGW 211 of the second mobile communication system 21B receives a packet with a destination IP address of UE 30 from the data network DN.

[0119] (Step S22B) In step S22B, the PGW 211 determines whether the destination IP address of the packet is stored in the PDN connection table. In other words, the PGW 211 determines whether a UE 30 to which the same IP address as the destination IP address of the packet is assigned is connected to the second mobile communication system 21B.

[0120] (Step S23B) If it is determined in step S22B that the destination IP address of the packet is stored in the PDN connection table (step S22B: YES), in step S23B, the PGW211 transmits the packet received in step S21B to the UE30 assigned the same IP address as the destination IP address via the SGW222 and the eNB221.

[0121] (Step S24B) In step S24B, UE 30 receives the packet transmitted in step S23B.

[0122] (Step S25B) On the other hand, if it is determined in step S22B that the destination IP address of the packet is not stored in the PDN connection table (step S22B: NO), the PGW 211 transmits the packet received in step S21B to the UPF 111 in step S25B.

[0123] (Step S26B) In step S26B, the UPF 111 of the first mobile communication system 11B receives the packet transmitted in step S25B.

[0124] (Step S27B) In step S27B, the UPF 111 determines whether the destination IP address of the packet is stored in the PDU session table. In other words, the UPF 111 determines whether a UE 30 assigned the same IP address as the destination IP address of the packet is connected to the first mobile communication system 11B.

[0125] (Step S28B) If, in step S27B, it is determined that the destination IP address of the packet is stored in the PDU session table (step S27B: YES), in step S28B, UPF111 transmits the packet received in step S26B via gNB121 to UE30 assigned the same IP address as the destination IP address.

[0126] (Step S29B) In step S29B, the UE 30 receives the packet transmitted in step S28B.

[0127] (Step S30B) On the other hand, if it is determined in step S27B that the destination IP address of the packet is not stored in the PDU session table (step S27B: NO), in step S30B, the UPF 111 discards the packet received in step S26B.

[0128] (Processing by UE30 to send packets) The process of UE 30 transmitting a packet will be described.

[0129] When the UE 30 is connected to the first mobile communication system 11A, the packet transmitted from the UE 30 is received by the UPF 111. The UPF 111 transmits the received packet to the PGW 211 of the second mobile communication system 21B. Then, the PGW 211 transmits the received packet to the data network DN.

[0130] On the other hand, when the UE 30 is connected to the second mobile communication system 21A, the PGW 211 receives the packets transmitted from the UE 30. Then, the PGW 211 transmits the received packets to the data network DN.

[0131] (Effects of Communication System 1B) As described above, in communication system 1B, UE 30 is assigned the same IP address in both first mobile communication system 11B and second mobile communication system 21B connected to data network DN. When UE 30 is connected to first mobile communication system 11A, packets addressed to UE 30 are transmitted from UPF 111 to PGW 211 and then transmitted from PGW 211 to UE 30. On the other hand, when UE 30 is connected to second mobile communication system 21B, packets addressed to UE 30 are transmitted from PGW 211 to UE 30.

[0132] Therefore, even in the communication system 1B, whether the UE 30 is connected to the first mobile communication system 11B or the second mobile communication system 21B, the UE 30 can communicate smoothly with either mobile communication system without changing its IP address.

[0133] [Variations] The user of UE 30 may be configured to be able to select which of the above-described communication systems 1A and 1B to use. In other words, the user of UE 30 may be configured to be able to select whether the first mobile communication system 11A communicates with the data network DN or the second mobile communication system 21B communicates with the data network DN.

[0134] [Software implementation example] Some or all of the functions of the first mobile communication systems 11A, 11B, the second mobile communication systems 21A, 21B (hereinafter also referred to as "the above systems"), the UPF 111, and the PGW 211 (hereinafter also referred to as "the above devices") may be realized by hardware such as an integrated circuit (IC chip), or by software.

[0135] In the latter case, each of the above systems and devices is realized by, for example, a computer that executes instructions from a program, which is software that realizes each function. An example of such a computer (hereinafter referred to as computer C) is shown in Figure 9. Figure 9 is a block diagram showing the hardware configuration of computer C that functions as each of the above systems and devices.

[0136] The computer C includes at least one processor C1 and at least one memory C2. The memory C2 stores a program P for causing the computer C to function as each of the above systems and devices. In the computer C, the processor C1 reads and executes the program P from the memory C2, thereby realizing the functions of each of the above systems and devices.

[0137] The processor C1 may be, for example, a central processing unit (CPU), a graphic processing unit (GPU), a digital signal processor (DSP), a micro processing unit (MPU), a floating point number processing unit (FPU), a physics processing unit (PPU), a tensor processing unit (TPU), a quantum processor, a microcontroller, or a combination thereof. The memory C2 may be, for example, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof.

[0138] The computer C may further include a RAM (Random Access Memory) for expanding the program P during execution and for temporarily storing various data. The computer C may also include a communication interface for transmitting and receiving data to and from other devices. The computer C may also include an input / output interface for connecting input / output devices such as a keyboard, mouse, display, and printer.

[0139] Furthermore, the program P can be recorded on a non-transitory tangible recording medium M that can be read by the computer C. Such a recording medium M can be, for example, a tape, a disk, a card, a semiconductor memory, or a programmable logic circuit. The computer C can acquire the program P via such a recording medium M. The program P can also be transmitted via a transmission medium. Such a transmission medium can be, for example, a communication network or broadcast waves. The computer C can also acquire the program P via such a transmission medium.

[0140] Furthermore, the functions of each of the systems and devices may be realized by a single processor provided in a single computer, by multiple processors provided in a single computer working in cooperation, or by multiple processors provided in each of multiple computers working in cooperation. Furthermore, the programs for causing each of the devices to realize the functions may be stored in a single memory provided in a single computer, or may be distributed and stored in multiple memories provided in a single computer, or may be distributed and stored in multiple memories provided in each of multiple computers.

[0141] [Appendix A] This disclosure includes the techniques described in the following appendices. However, the present invention is not limited to the techniques described in the following appendices, and various modifications are possible within the scope of the claims.

[0142] (Appendix A1) A communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, The first mobile communication system communicating with a device external to the first mobile communication system; storing a mobile terminal connected to the first mobile communication system in association with an IP address of the mobile terminal; a first gateway means; The second mobile communication system communicating with a device external to the second mobile communication system; storing a mobile terminal connected to the second mobile communication system in association with an IP address of the mobile terminal; a second gateway means; the first gateway means and the second gateway means each associate the same IP address with the same mobile terminal and store the IP address; the first gateway means, when a destination IP address of a packet received from the external device is not stored in association with the mobile terminal, transmits the packet to the second gateway means; Communication system.

[0143] (Appendix A2) The mobile terminal communicating with the first mobile communication system using the installed first SIM; communicating with the second mobile communication system using a second SIM installed therein, the second SIM being different from the first SIM; the first gateway means stores an identifier of the first SIM and an IP address of the mobile terminal in association with each other; the second gateway means stores the identifier of the second SIM and the IP address of the mobile terminal in association with each other; 1. A communication system as described in Appendix A1.

[0144] (Appendix A3) One of the first mobile communication system and the second mobile communication system is an sXGP system, and the other is a local 5G system; 1. A communication system according to claim A1 or A2.

[0145] (Appendix A4) the first gateway means stores the IP address of the second gateway means; 10. A communication system according to any one of appendices A1 to A3.

[0146] (Appendix A5) the first gateway means and the second gateway means each further include a registration means for associating the same IP address with the same mobile terminal and storing the same IP address; 10. A communication system according to any one of appendices A1 to A4.

[0147] (Appendix A6) the second gateway means transmits and receives data to and from a data network via the first gateway means; 10. A communication system according to any one of appendices A1 to A5.

[0148] [Appendix B] This disclosure includes the techniques described in the following appendices. However, the present invention is not limited to the techniques described in the following appendices, and various modifications are possible within the scope of the claims.

[0149] (Appendix B1) a first mobile communication system for communicating with an external device; and a second mobile communication system different from the first mobile communication system, the second mobile communication system communicating with an external device; A communication method performed by a communication system including: a first storage process for storing a mobile terminal connected to the first mobile communication system in association with an IP address of the mobile terminal; a second storage process for storing a mobile terminal connected to the second mobile communication system in association with an IP address of the mobile terminal; In the first storage process and the second storage process, the same IP address is stored in association with the same mobile terminal; The communication method further includes a transmission process of transmitting a packet received by the first mobile communication system from the external device to the second mobile communication system when the destination IP address of the packet is not stored in the first storage process in association with the mobile terminal; A communication method including:

[0150] (Appendix B2) The mobile terminal communicating with the first mobile communication system using the installed first SIM; communicating with the second mobile communication system using a second SIM installed therein, the second SIM being different from the first SIM; The communication system includes: In the first storage process, an identifier of the first SIM and an IP address of the mobile terminal are stored in association with each other; In the first storage process, the identifier of the second SIM and the IP address of the mobile terminal are stored in association with each other. The communication method described in Appendix B1.

[0151] (Appendix B3) One of the first mobile communication system and the second mobile communication system is an sXGP system, and the other is a local 5G system; A communication method as described in Appendix B1 or B2.

[0152] (Appendix B4) The first mobile communication system stores an IP address of the second mobile communication system. 1. A communication method according to any one of appendices B1 to B3.

[0153] (Appendix B5) The first storage process and the second storage process each further include a registration process for storing the same IP address in association with the same mobile terminal. 1. A communication method according to any one of appendices B1 to B4.

[0154] (Appendix B6) the second mobile communication system transmits and receives data to and from a data network via the first mobile communication system; 1. A communication method according to any one of Appendices B1 to B5.

[0155] [Appendix C] This disclosure includes the techniques described in the following appendices. However, the present invention is not limited to the techniques described in the following appendices, and various modifications are possible within the scope of the claims.

[0156] (Appendix C1) A program that causes a computer to function as a communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, The computer communicating with a device external to the first mobile communication system; storing a mobile terminal connected to the first mobile communication system in association with an IP address of the mobile terminal; a first gateway means; communicating with a device external to the second mobile communication system; storing a mobile terminal connected to the second mobile communication system in association with an IP address of the mobile terminal; a second gateway means; the first gateway means and the second gateway means each associate the same IP address with the same mobile terminal and store the IP address; the first gateway means, when a destination IP address of a packet received from the external device is not stored in association with the mobile terminal, transmits the packet to the second gateway means; program.

[0157] (Appendix C2) The mobile terminal communicating with the first mobile communication system using the installed first SIM; communicating with the second mobile communication system using a second SIM installed therein, the second SIM being different from the first SIM; the first gateway means stores an identifier of the first SIM and an IP address of the mobile terminal in association with each other; the second gateway means stores the identifier of the second SIM and the IP address of the mobile terminal in association with each other; The program described in Appendix C1.

[0158] (Appendix C3) One of the first mobile communication system and the second mobile communication system is an sXGP system, and the other is a local 5G system; A program as described in Appendix C1 or C2.

[0159] (Appendix C4) the first gateway means stores the IP address of the second gateway means; A program according to any of Appendices C1 to C3.

[0160] (Appendix C5) the first gateway means and the second gateway means each further include a registration means for associating the same IP address with the same mobile terminal and storing the same IP address; A program according to any of Appendices C1 to C4.

[0161] (Appendix C6) the second gateway means transmits and receives data to and from a data network via the first gateway means; A program according to any of Appendices C1 to C5.

[0162] [Appendix D] This disclosure includes the techniques described in the following appendices. However, the present invention is not limited to the techniques described in the following appendices, and various modifications are possible within the scope of the claims.

[0163] (Appendix D1) A communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, at least one processor, communicating with a device external to the first mobile communication system; storing a mobile terminal connected to the first mobile communication system in association with an IP address of the mobile terminal; a first gateway process; communicating with a device external to the second mobile communication system; storing a mobile terminal connected to the second mobile communication system in association with an IP address of the mobile terminal; a second gateway process; In each of the first gateway process and the second gateway process, the same IP address is associated with the same mobile terminal and stored; In the first gateway process, if the destination IP address of the packet received from the external device is not stored in association with the mobile terminal, the packet is transmitted to the second mobile communication system. Communication system.

[0164] (Appendix D2) The mobile terminal communicating with the first mobile communication system using the installed first SIM; communicating with the second mobile communication system using a second SIM installed therein, the second SIM being different from the first SIM; The at least one processor: In the first gateway process, an identifier of the first SIM and an IP address of the mobile terminal are stored in association with each other; In the second gateway process, an identifier of the second SIM and an IP address of the mobile terminal are stored in association with each other. 10. The communication system of claim D1.

[0165] (Appendix D3) One of the first mobile communication system and the second mobile communication system is an sXGP system, and the other is a local 5G system; 10. A communication system according to claim D1 or D2.

[0166] (Appendix D4) The at least one processor stores an IP address of the second mobile communication system in the first gateway process. 10. A communication system according to any one of appendices D1 to D3.

[0167] (Appendix D5) the at least one processor further executes a registration process in each of the first gateway process and the second gateway process, in which the same IP address is associated with and stored in the same mobile terminal; 10. A communication system according to any one of appendices D1 to D4.

[0168] (Appendix D6) the at least one processor, in the second gateway processing, transmits and receives data to and from a data network via the first mobile communication system; 10. A communication system according to any one of appendices D1 to D5.

[0169] [Appendix E] This disclosure includes the techniques described in the following appendices. However, the present invention is not limited to the techniques described in the following appendices, and various modifications are possible within the scope of the claims.

[0170] (Appendix E1) A non-transitory recording medium having recorded thereon a program that causes a computer to function as a communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, The computer communicating with a device external to the first mobile communication system; storing a mobile terminal connected to the first mobile communication system in association with an IP address of the mobile terminal; a first gateway means; communicating with a device external to the second mobile communication system; storing a mobile terminal connected to the second mobile communication system in association with an IP address of the mobile terminal; a second gateway means; the first gateway means and the second gateway means each associate the same IP address with the same mobile terminal and store the IP address; the first gateway means, when a destination IP address of a packet received from the external device is not stored in association with the mobile terminal, transmits the packet to the second gateway means; A non-transitory recording medium on which a program is recorded. [Explanation of symbols]

[0171] 1, 1A, 1B communication system 11, 11A, 11B First mobile communication system 21, 21A, 21B Second mobile communication system 111 First Gateway Unit, UPF 112, 212 Registration Department 211 Second Gateway Unit, PGW 30 Mobile Terminal, UE

Claims

1. A communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, The first mobile communication system communicating with a device external to the first mobile communication system; The mobile terminal connected to the first mobile communication system is stored in association with the IP address of the mobile terminal. a first gateway means; the second mobile communication system communicating with a device external to the second mobile communication system; The mobile terminal connected to the second mobile communication system is stored in association with the IP address of the mobile terminal. a second gateway means; the first gateway means and the second gateway means each associate the same IP address with the same mobile terminal and store the IP address; the first gateway means, when a destination IP address of a packet received from the external device is not stored in association with the mobile terminal, transmits the packet to the second gateway means; Communication system.

2. The mobile terminal communicating with the first mobile communication system using an on-board first SIM; communicating with the second mobile communication system using an on-board second SIM, the second SIM being different from the first SIM; the first gateway means stores an identifier of the first SIM and an IP address of the mobile terminal in association with each other; the second gateway means stores an identifier of the second SIM and an IP address of the mobile terminal in association with each other; The communication system of claim 1 .

3. One of the first mobile communication system and the second mobile communication system is an sXGP system, and the other is a local 5G system.

3. A communication system according to claim 1 or 2.

4. the first gateway means stores the IP address of the second gateway means; 3. A communication system according to claim 1 or 2.

5. the first gateway means and the second gateway means each further include a registration means for associating the same IP address with the same mobile terminal and storing the same IP address; 3. A communication system according to claim 1 or 2.

6. the second gateway means transmits and receives data to and from a data network via the first gateway means; 3. A communication system according to claim 1 or 2.

7. a first mobile communication system for communicating with an external device; and a second mobile communication system different from the first mobile communication system, the second mobile communication system communicating with an external device; A communication method performed by a communication system including: a first storage process for storing a mobile terminal connected to the first mobile communication system in association with an IP address of the mobile terminal; a second storage process for storing a mobile terminal connected to the second mobile communication system in association with an IP address of the mobile terminal; In the first storage process and the second storage process, the same IP address is stored in association with the same mobile terminal; The communication method further includes a process of transmitting a packet to the second mobile communication system when a destination IP address of the packet received by the first mobile communication system from the external device has not been stored in the first storage process in association with the mobile terminal; A communication method including:

8. A program that causes a computer to function as a communication system including a first mobile communication system and a second mobile communication system different from the first mobile communication system, The computer communicating with a device external to the first mobile communication system; The mobile terminal connected to the first mobile communication system is stored in association with the IP address of the mobile terminal. a first gateway means; communicating with a device external to the second mobile communication system; The mobile terminal connected to the second mobile communication system is stored in association with the IP address of the mobile terminal. a second gateway means; the first gateway means and the second gateway means each associate the same IP address with the same mobile terminal and store the IP address; the first gateway means, when a destination IP address of a packet received from the external device is not stored in association with the mobile terminal, transmits the packet to the second gateway means; program.

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