Communication system, network device, and communication control method

Abstract

To allow a communication without an intent of the change of an address even if a mobile communication business operator is changed.SOLUTION: A communication system connected to two or more mobile communication business operator networks, comprises: a management device that is provided corresponding to each of the mobile communication business operator networks, and manages user information; a gateway device that transfers a packet transmitted and received by a terminal connected to each mobile communication business operator network; and an adapter device that transfers the packet between each mobile communication business operator network and an external network. The adapter device gives an address, which can be used even if the mobile communication business operator network connected by the terminal is changed, to the terminal, and the terminal uses the address given from the adapter device and connects to the mobile communication business operator network.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a communication system.

Background Art

[0002] In recent years, with the liberalization of the line business in the communication business market, virtual mobile network operators (MVNOs) without network facilities have been providing virtual mobile communication services. In recent years, full MVNOs, which are the top services of conventional light MVNOs, have emerged. Full MVNOs attempt to achieve so-called multi-carrier operation by using SIMs of multiple mobile network operators according to customer requirements and situations.

[0003] As the background art in this technical field, there are the following prior arts. Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-516198) discloses a method for transmitting data packets from a client device to a cloud, wherein the data packets are included in communication, the cloud is composed of a plurality of media nodes and a plurality of gateway nodes, the media nodes and the gateway nodes are hosted on a server, and the method includes transmitting a first data packet included in the communication from the client device to a first gateway node, and transmitting a second data packet included in the communication from the client device to a second gateway node.

[0004] Further, Patent Document 2 (Japanese Patent Application Laid-Open No. 2015-39186) discloses a wireless communication method including communicating via an anchor carrier wave and at least one first secondary carrier wave, receiving an instruction to change the at least one first secondary carrier wave, and in response to the instruction, deactivating the at least one first secondary carrier wave or activating at least one subsequent secondary carrier wave.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Special Publication No. 2020-516198 [Patent Document 2] Japanese Patent Publication No. 2015-39186 [Overview of the project] [Problems that the invention aims to solve]

[0006] For a full MVNO to achieve multi-carrier capabilities, coordinated connectivity between mobile carriers is necessary. However, since each mobile carrier has different equipment specifications, simple coordination is difficult.

[0007] Furthermore, when switching between the systems of different mobile carriers from a communication terminal, the communication session needs to be re-authenticated because the mobile carriers are not coordinated with each other. As a result, communication is temporarily interrupted on the communication terminal during the re-authentication process. In other words, in the conventional configuration, each mobile carrier has its own PGW, PCEF, and other equipment, so the equipment of each carrier operates independently without coordination. Therefore, if communication in the wireless section is interrupted on the equipment of one carrier, the communication is interrupted. In particular, this has the effect of increasing latency in real-time communication.

[0008] Furthermore, even with multi-SIM support, from the application's perspective, communication will still occur via separate equipment belonging to each mobile carrier. [Means for solving the problem]

[0009] A representative example of the invention disclosed in this application is as follows: a communication system connected to two or more mobile carrier networks, comprising a management device provided corresponding to each of the mobile carrier networks for managing user information, and a system for forwarding packets transmitted and received by terminals connected to the mobile carrier networks. Furthermore, the terminal is assigned an address that can be used even if the mobile carrier network to which the terminal is connected changes. A gateway device and The adapter device uses the address recorded in its database to forward packets destined for the terminal, received from an external network, into the mobile carrier network. The terminal comprises an adapter device, and the terminal is the The address assigned by the gateway device is recorded, and the terminal uses the address recorded therein.It is characterized by connecting to the aforementioned mobile communications carrier network. [Effects of the Invention]

[0010] According to one aspect of the present invention, communication becomes possible without being aware of address changes, even when switching communication routes across mobile carriers. Other problems, configurations, and effects will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing the configuration of the network system in Example 1. [Figure 2] This figure shows the network state of the terminal in Example 1 before the communication path was changed. [Figure 3] This figure shows the network status after the communication path of the terminal in Example 1 has been changed. [Figure 4] This figure shows the SIM card implemented in the terminal of Example 1. [Figure 5] This diagram shows the configuration of the IP adapter in Example 1. [Figure 6] This diagram shows the table structure of the adapter database in Example 1. [Figure 7] This is a sequence diagram of the virtual IP address registration process on the mobile network operator A side in Example 1. [Figure 8] This is a sequence diagram of the virtual IP address registration process on the mobile network operator B side in Example 1. [Figure 9] This is a sequence diagram of the communication route change process triggered by a message from the terminal in Example 1. [Figure 10] This is a sequence diagram of the communication route change process in Example 1 that is not triggered by a message from the terminal. [Figure 11] This figure shows the SIM card implemented in the terminal of Example 2. [Figure 12] This figure shows the table structure of the adapter database in Example 2. [Figure 13] It is a sequence diagram of the IP address registration process on the side of mobile network operator A in Embodiment 2. [Figure 14] It is a sequence diagram of the virtual IP address registration process on the side of mobile network operator B in Embodiment 2. [Figure 15] It is a sequence diagram of the communication route change process in Embodiment 2.

Modes for Carrying Out the Invention

[0012] <Embodiment 1> FIG. 1 is a diagram showing the configuration of the network system 100 of Embodiment l of the present invention.

[0013] The network system 100 of this embodiment is a network system 100 that connects the network 200 of mobile network operator A and the network 300 of mobile network operator B, and is installed by, for example, a full MVNO operator.

[0014] In this embodiment, a terminal 400 connected to the network 200 of mobile network operator A or the network 300 of mobile network operator B communicates with an application server (not shown) on the Internet 500.

[0015] The network system 100 includes HSSs 101A and 101B, PGW·PCEFs 102A and 102B, authentication devices 103A and 103B, PCRFs 104A and 104B, OCSs 105A and 105B, and an IP adapter 110. The HSSs 101A and 101B, PGWs 102A and 102B, authentication devices 103A and 103B, PCRFs 104A and 104B, and OCSs 105A and 105B are provided in pairs corresponding to each of the network 200 of mobile network operator A and the network 300 of mobile network operator B.

[0016] The HSS (Home Subscriber Server) 101A and 101B are subscriber management devices that manage user information such as contract information and authentication information, and notify the IP adapter 110 of this information when the location of the terminal 400 is registered. The PGW / PCEF (Packet data network Gateway / Policy and Charging Enforcement Function) 102A and 102B are gateway devices that send and receive packets to and from the networks 200 and 300 of each mobile carrier according to the policies instructed by the PCRF 104A and 104B. The authentication devices 103A and 103B authenticate the terminals 400 of their own subscribers that are connected to the networks 200 and 300 of each mobile carrier. The PCRF (Policy and Charging Rule Function) 104A and 104B are policy management devices that manage network policies and billing rules. The OCS (Online Charging System) 105A and 105B are billing management devices that manage the user's packet traffic based on the packet volume notified by the PGW / PCEF 102A and 102B, and notify the PCRF 104A and 104B of the packet traffic volume.

[0017] The IP adapter 110 includes an adapter database 111 and an address adapter 112. The adapter database 111 is a database that manages information about the terminal 400, the virtual IP address of the terminal 400, and the communication status of the terminal 400, and its details will be explained with reference to Figure 5. The address adapter 112 distributes packets destined for the terminal 400 to the PGW / PCEF 102A, 102B (i.e., the networks 200, 300 of each mobile carrier) according to the information recorded in the adapter database 111.

[0018] Virtual IP addresses are managed by PGW-PCEF102A and 102B based on information notified from IP adapter 110 and adapter database 111. Full MVNOs have PGW-PCEF102A and 102B as their own equipment, so PGW-PCEF102A and 102B can manage virtual IP addresses used across mobile carriers. For example, when setting the IMSI, PGW-PCEF102A and 102B set a virtual IP address associated with the IMSI and register it with HSS101A and 101B. Alternatively, PGW-PCEF102A and 102B may assign a virtual IP address when authenticating terminal 400.

[0019] The network 200 of mobile carrier A has multiple base station devices (eNodeB) 201A, one or more MMEs 202A, and an SGW 203A. The base station devices 201A communicate wirelessly with terminals 400. The MME (Mobility Management Entity) 202A is a device that accommodates the base station devices 201A and provides mobility control (e.g., status management, location management, paging control, security information management of terminals 400). The SGW (Serving Gateway) 203A is a local packet gateway that manages the communication paths between the base station devices 201A, the SGW 203A, and the PGW / PCEF 102A.

[0020] The network 300 of mobile carrier B has multiple base station devices (eNodeB) 301B, one or more MMEs (Mobility Management Entities) 302B, and an SGW (Serving Gateway) 303B. Each of these devices is the same as those described for the network 200 of mobile carrier A.

[0021] Figure 2 shows the network state before the communication path was changed, and Figure 3 shows the network state after the communication path was changed.

[0022] In this embodiment, terminal 400 is assigned both a real IP address and a virtual IP address, and the address visible to the application server is the virtual IP address. Furthermore, information about terminal 400 from HSS101A and 101B is shared with PGW / PCEF102A and 102B and IP adapter 110 to forward packets.

[0023] Specifically, the IP adapter 110 maintains a table of packet forwarding routes, corresponding IMSIs, actual IP addresses, and virtual IP addresses, and modifies the route of packets received from the Internet 500 side.

[0024] PGW·PCEF102A and 102B assign a virtual IP address and a real IP address to terminal 400. Terminal 400 connects to a mobile carrier's network where the communication conditions are stable (e.g., strong signal strength). Since the address used for communication is the virtual IP address, the application server communicates with terminal 400 using the virtual IP address.

[0025] Terminal 400 communicates with the Internet 500 using a virtual IP address via the network of a mobile carrier with strong signal strength. For example, if the signal strength of Terminal 400 decreases, it sends a communication route change message to the IP adapter 110. The IP adapter 110 detects the communication route change message from Terminal 400, and also detects a change in the communication route using the virtual IP address (for example, communication from the current mobile carrier via the network of another mobile carrier with strong signal strength), and determines that the communication route using the virtual IP address has changed, and changes the route of packets received from the Internet 500. In this way, even if the communication route from Terminal 400 changes, communication from the Internet 500 to Terminal 400 is not interrupted.

[0026] Figure 4 shows the SIM card installed in terminal 400.

[0027] Terminal 400 is equipped with a number of SIMs corresponding to the number of mobile carriers with which it can communicate. The SIMs (Subscriber Identity Modules) installed in terminal 400 may be physical SIMs using IC cards or eSIMs written to the memory of terminal 400. SIM(a) records the IMSI(a) for mobile carrier A, the actual IP address a for communication with mobile carrier A, and the virtual IP address c for communication with the internet 500. SIM(b) records the IMSI(b) for mobile carrier B, the actual IP address b for communication with mobile carrier B, and the virtual IP address c for communication with the internet 500. The virtual IP address c recorded in SIM(a) and the virtual IP address c recorded in SIM(b) are the same.

[0028] Terminal 400 can communicate on mobile carrier A's network 200 using either the real IP address a or the virtual IP address c, and can communicate on mobile carrier B's network 300 using either the real IP address b or the virtual IP address c. Therefore, terminal 400 normally communicates on mobile carrier A's network 200 and mobile carrier B's network 300 using the virtual IP address c.

[0029] Figure 5 shows the configuration of the IP adapter 110.

[0030] The IP adapter 110 has an adapter database 111 and an address adapter 112.

[0031] The adapter database 111 has tables that manage information about terminal 400, the virtual IP address of terminal 400, and the communication status of terminal 400. Details of the adapter database 111 will be explained with reference to Figure 5. The adapter database 111 is composed of a computer having a processor, memory, auxiliary storage device (HDD), and communication interface (NIC). The processor is an arithmetic unit that executes programs stored in memory. The functions provided by the IP adapter 110 are realized by the processor executing various programs. Note that some of the processing performed by the processor when executing programs may be performed by other arithmetic units (e.g., hardware such as ASICs and FPGAs). The memory includes non-volatile memory elements such as ROM and volatile memory elements such as RAM. ROM stores immutable programs (e.g., BIOS). RAM is a high-speed, volatile memory element such as DRAM (Dynamic Random Access Memory) that temporarily stores programs executed by the processor and data used during program execution. The auxiliary storage device (HDD) is a large-capacity, non-volatile storage device such as a magnetic storage device that stores programs executed by the processor and data used by the processor during program execution. A communication interface is a network interface device that controls communication with other devices according to a predetermined protocol.

[0032] The address adapter 112 distributes packets destined for terminal 400 to PGW / PCEF 102A and 102B (i.e., the networks 200 and 300 of each mobile carrier) according to the information recorded in the adapter database 111. The address adapter 112 is composed of a computer having a processor, memory, auxiliary storage device, and communication interface (NIC). The processor is an arithmetic unit that executes programs stored in memory. The functions provided by the IP adapter 110 are realized by the processor executing various programs. Note that some of the processing performed by the processor by executing programs may be executed by other arithmetic units (e.g., hardware such as ASICs and FPGAs). The memory includes ROM, which is a non-volatile memory element, and RAM, which is a volatile memory element. ROM stores immutable programs (e.g., BIOS). RAM is a high-speed, volatile memory element such as DRAM (Dynamic Random Access Memory) and temporarily stores programs executed by the processor and data used when executing programs. The auxiliary storage device is a high-capacity, non-volatile storage device, such as a magnetic storage device, that stores the program executed by the processor and the data used by the processor during program execution. The communication interface is a network interface device that controls communication with other devices according to a predetermined protocol.

[0033] Figure 6 shows the table structure of the adapter database 111.

[0034] As shown in Figure 6(A), the adapter database 111 tables store data such as communication route, IMSI, actual IP address, virtual IP address, and communication status in association with each other. The communication route is the identification information of the mobile carrier network through which the communication sent and received by terminal 400 passes. The IMSI is the subscriber identification number issued to terminal 400 and is recorded on the SIM implemented in terminal 400. The actual IP address is the address that terminal 400 uses to communicate on each mobile carrier's network. The virtual IP address is the address that terminal 400 uses to communicate with the internet 500. The communication status is data that indicates whether terminal 400 is in the ACTIVE state, communicating on each mobile carrier's network, or in the STANDBY state, where communication is paused.

[0035] The IMSI, actual IP address, and virtual IP address of the adapter database 111 are configured as part of the IP adapter configuration definition using an interface such as a GUI (Graphical User Interface).

[0036] The adapter database 111 may include connection priority information. Terminal 400 preferentially connects to the network of the mobile carrier with the highest connection priority.

[0037] The adapter database 111 may include 5-tuple information (source IP address, source port number, destination IP address, destination port number, protocol number), and the communication route can be changed for each application by associating the communication route with the 5-tuple information.

[0038] Figure 7 is a sequence diagram of the virtual IP address registration process on the mobile network operator A side.

[0039] First, when issuing a SIM for terminal 400, the IP adapter 110 assigns an IMSI to the SIM of terminal 400 and provisionally registers the IMSI(a) for mobile carrier A, the actual IP address a for mobile carrier A, the IMSI(b) for mobile carrier B, the actual IP address b for mobile carrier B, and the virtual IP address c in the adapter database 111 (1001). Then, the IP adapter 110 sends the IMSI(a) for mobile carrier A, the actual IP address a, and the virtual IP address c to PGW / PCEF102A and requests registration of the IMSI(a) and virtual IP address c (1002).

[0040] Furthermore, when terminal 400 attempts to connect to mobile carrier A's network 200 (1003), HSS101A requests PGW / PCEF102A to authenticate terminal 400 (1004). Once authentication of terminal 400 is complete (1005), PGW / PCEF102A sends IMSI(a), actual IP address a, and virtual IP address c to HSS101A and requests registration (1006). PGW / PCEF102A responds to terminal 400 with authentication success (1007). At this time, PGW / PCEF102A may also notify terminal 400 of the actual IP address a and virtual IP address c.

[0041] HSS101A sends the identification information of mobile carrier A's network 200, the IMSI for mobile carrier A, the actual IP address a for mobile carrier A, the virtual IP address c, and the communication status on mobile carrier A's network 200 to the IP adapter 110 and requests registration (1008). Then, the data of mobile carrier A is registered in the adapter database 111 (1009).

[0042] Figure 8 is a sequence diagram of the virtual IP address registration process on the mobile network operator B side.

[0043] First, the IP adapter 110 sends the IMSI(b), actual IP address b, and virtual IP address c for mobile carrier B, which were provisionally registered in step 1001 of Figure 7, to the PGW / PCEF102B and requests registration of the IMSI(b) and virtual IP address c (1012).

[0044] Furthermore, when terminal 400 attempts to connect to the network 300 of mobile carrier B (1013), HSS101B requests PGW / PCEF102B to authenticate terminal 400 (1014). Once authentication of terminal 400 is complete (1015), PGW / PCEF102B sends the IMSI(b), the actual IP address b, and the virtual IP address c to HSS101B and requests registration (1016). PGW / PCEF102B responds to terminal 400 with authentication success (1017). At this time, PGW / PCEF102B may also notify terminal 400 of the actual IP address b and the virtual IP address c.

[0045] HSS101B sends the identification information of mobile carrier B's network 300, the IMSI for mobile carrier B, the actual IP address b for mobile carrier B, the virtual IP address c, and the communication status on mobile carrier B's network 300 to the IP adapter 110 and requests registration (1018). Then, the data of mobile carrier B is registered in the adapter database 111 (1019).

[0046] Figure 9 is a sequence diagram of the communication route change process triggered by a message from terminal 400.

[0047] First, when terminal 400 detects a decrease in signal strength transmitted from base station equipment 301B of mobile carrier B while communicating via network 300 of mobile carrier B (1101), it sends a route change request message to IP adapter 110 via base station equipment 301B, SGW303B, and PGW / PCEF102B during communication (1102).

[0048] The IP adapter 110 sends an acknowledgment message for receiving the route change request message to the terminal 400 via the PGW / PCEF102B, SGW303B, and base station equipment 301B (1103). This acknowledgment message includes information about the changed packet forwarding route. After a predetermined time has elapsed since receiving the route change request message, the IP adapter 110 changes the packet forwarding route destined for terminal 400 from the network 300 of mobile carrier B to the network of another mobile carrier (e.g., company A) (1104). This predetermined time should be sufficient to allow time for the acknowledgment message to reach terminal 400 and for terminal 400 to complete the change of the packet forwarding route.

[0049] When terminal 400 receives a reception confirmation message from IP adapter 110, it identifies the modified packet forwarding route according to the information contained in the reception confirmation message, connects to the network 200 of mobile carrier A which constitutes the modified packet forwarding route, and changes the packet forwarding route to network 200 of mobile carrier A (1105).

[0050] Subsequently, terminal 400 continues communication via the network 200 of mobile carrier A (1106).

[0051] Furthermore, after the packet forwarding route is changed, terminal 400 may either maintain a standby state with the mobile carrier B's network 300 that was in use before the packet forwarding route was changed, or it may disconnect.

[0052] Figure 10 is a sequence diagram of the communication route change process that is not triggered by a message from terminal 400.

[0053] First, when terminal 400 detects a decrease in signal strength transmitted from base station equipment 301B of mobile carrier B while communicating via network 300 of mobile carrier B (1111), it connects to network 200 of mobile carrier A, which constitutes the modified packet forwarding route, changes the packet forwarding route (1112), and transmits packets via network 200 of mobile carrier A (1113).

[0054] The IP adapter 110 monitors the arrival route of packets from terminal 400, and when it detects the arrival of packets from terminal 400 via a different route than before (for example, the network 200 of mobile carrier A) (1114), it changes the packet forwarding route from the IP adapter 110 to terminal 400 to the network 200 of mobile carrier A where the packets from terminal 400 arrived (1115).

[0055] In this way, the terminal 400 and the IP adapter 110 change the packet forwarding route, and packets are forwarded bidirectionally via the network 200 of mobile carrier A after the route change (1116).

[0056] As described above, according to Embodiment 1 of the present invention, even when switching mobile carriers, bidirectional real-time communication becomes possible without being aware of changes in IP addresses.

[0057] <Example 2> Next, Embodiment 2 of the present invention will be described. In Embodiment 2, terminal 400 uses the IP address recorded in the SIM before the switch, even on the route after the switch, to forward packets. In addition, the middleware of terminal 400 temporarily maintains the session with the application and continues communication at the packet forwarding route switching timing. Note that in Embodiment 2, mainly the differences from Embodiment 1 described above will be explained, and the same configuration and processing as in Embodiment 1 will be omitted.

[0058] The network system 100 of Example 2 is configured as shown in Figure 1, similar to Example 1. PGW·PCEF102A, 102B assign actual IP addresses to terminal 400. Terminal 400 connects to a mobile carrier's network where communication conditions are stable (e.g., strong signal strength). The address visible from the application server on the Internet 500 is the actual IP address. When switching packet forwarding routes, the IP address of the SIM is rewritten. The middleware of terminal 400 maintains a session with the application program for a certain period of time while the IP address within terminal 400 is changing, thereby continuing communication between the application server and terminal 400.

[0059] Figure 11 shows the SIM card installed in terminal 400 of Example 2.

[0060] Terminal 400 is equipped with a number of SIMs corresponding to the number of mobile carriers with which it can communicate. The SIMs installed in terminal 400 are preferably eSIMs that are written to the memory of terminal 400. SIM(a) records the IMSI(a) for mobile carrier A and the actual IP address a for communication with mobile carrier A. SIM(b) records the IMSI(b) for mobile carrier B and the actual IP address b for communication with mobile carrier B.

[0061] Terminal 400 can communicate on mobile carrier A's network 200 and mobile carrier B's network 300 using either actual IP address a or actual IP address b.

[0062] Figure 12 shows the table structure of the adapter database 111.

[0063] As shown in Figure 12(A), the adapter database 111 table stores data such as communication route, IMSI, terminal-specific ID, and priority in association with each other. The communication route is the identification information of the mobile carrier network through which communications sent and received by terminal 400 pass. The IMSI is the subscriber identification number issued to terminal 400 and is recorded on the SIM implemented in terminal 400. The terminal-specific ID is identification information uniquely assigned to terminal 400. This may be the IMEI (International Mobile Equipment Identity), which is the serial number of terminal 400, or a unique identification information determined independently by the MVNO operator. The virtual IP address is the address that terminal 400 uses to communicate with the internet 500. The priority is the priority for terminal 400 to connect to the mobile carrier network.

[0064] The IMSI of adapter database 111 is configured using an interface such as a GUI (Graphical User Interface) as part of the IP adapter configuration definition.

[0065] The adapter database 111 may include 5-tuple information (source IP address, source port number, destination IP address, destination port number, protocol number), and the communication route can be changed for each application by associating the communication route with the 5-tuple information.

[0066] Figure 13 is a sequence diagram of the IP address registration process on the mobile network operator A side in Example 2.

[0067] First, when issuing a SIM for terminal 400, the IP adapter 110 assigns IMSI(a) to the SIM for mobile carrier A and IMSI(b) for mobile carrier B to terminal 400, and provisionally registers the assigned IMSIs in the adapter database 111 (1201).

[0068] Furthermore, when terminal 400 attempts to connect to mobile carrier A's network 200 (1203), HSS101A requests PGW / PCEF102A to authenticate terminal 400 (1204). If PGW / PCEF102A can authenticate terminal 400, it requests IP adapter 110 to assign an IP address (1205). In response to the IP address assignment request, IP adapter 110 determines the IP address of terminal 400 that attempted to connect, and records the determined IP address in the adapter database 111, associating it with IMSI(a).

[0069] The IP adapter 110 sends the determined IP address to the PGW / PCEF102A and requests registration of the IP address (1206). Once the IP address registration is complete, the PGW / PCEF102A completes the authentication process (1207) and responds to terminal 400 with a successful authentication (1208).

[0070] Figure 14 is a sequence diagram of the virtual IP address registration process on the mobile carrier B side in Example 2.

[0071] After the IMSI(a) for mobile carrier A and the IMSI(b) for mobile carrier B are registered in step 1201 of Figure 13, when terminal 400 attempts to connect to mobile carrier A's network 200 (1213), HSS101B requests PGW / PCEF102B to authenticate terminal 400 (1214). If PGW / PCEF102B can authenticate terminal 400, it requests IP adapter 110 to assign an IP address (1215). In response to the IP address assignment request, IP adapter 110 determines the IP address of terminal 400 that attempted to connect and records the determined IP address in the adapter database 111, associating it with IMSI(b).

[0072] The IP adapter 110 sends the determined IP address to the PGW / PCEF102B and requests registration of the IP address (1216). Once the PGW / PCEF102B has finished registering the IP address, it completes the authentication process (1217) and responds to terminal 400 with a successful authentication (1218).

[0073] Figure 15 is a sequence diagram of the communication route change process in Example 2.

[0074] First, when the middleware of terminal 400 detects a decrease in the signal strength transmitted from the base station equipment 301B of mobile carrier B while communicating via the network 300 of mobile carrier B (1221), it sends a route change request message to the IP adapter 110 via the communication module B of terminal 400 (a communication module that communicates with the network 300 of mobile carrier B) (1222).

[0075] The IP adapter 110 sends an IP address change notification to PGW-PCEF102A on the mobile carrier A side and PGW-PCEF102B on the mobile carrier B side (1223, 1224). PGW-PCEF102B sends an IP address change notification to terminal 400 (1225).

[0076] When terminal 400's OS receives an IP address change notification from PGW / PCEF102B, it rewrites the IP address a of the SIM card installed for mobile carrier A to the IP address b currently being used for communication.

[0077] When the middleware of terminal 400 detects a change in IP address due to SIM rewriting (1226), it disconnects the session with communication module B and continues the session with the application software running on terminal 400 (1227).

[0078] Mobile carrier A's PGW, PCEF102A, sends an IP address change notification to terminal 400 (1228).

[0079] When the middleware of terminal 400 detects a change in IP address (1229), it establishes a session with communication module A, which communicates with the network of mobile carrier A, and maintains a session with the application software running on terminal 400.

[0080] Subsequently, terminal 400 continues communication via mobile carrier A's network 200 using IP address b (1230).

[0081] As described above, according to Embodiment 2 of the present invention, real-time bidirectional communication is possible without using a virtual IP address, even when switching mobile carriers, without being aware of the change in IP address.

[0082] It should be noted that the present invention is not limited to the embodiments described above, but includes various modifications and equivalent configurations within the spirit of the attached claims. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and the present invention is not necessarily limited to having all the described configurations. Furthermore, some of the configurations of one embodiment may be replaced with those of another embodiment. Furthermore, configurations of other embodiments may be added to the configuration of one embodiment. Furthermore, some of the configurations of each embodiment may be added, deleted, or replaced with those of other embodiments.

[0083] Furthermore, each of the aforementioned configurations, functions, processing units, and processing means may be implemented in hardware, for example, by designing them as integrated circuits, or they may be implemented in software by having a processor interpret and execute programs that realize each function.

[0084] Information such as programs, tables, and files that implement each function can be stored in memory, hard disks, SSDs (Solid State Drives), or other storage media such as IC cards, SD cards, and DVDs.

[0085] Furthermore, the control lines and information lines shown are those deemed necessary for explanation purposes and do not necessarily represent all control lines and information lines required for implementation. In reality, it can be assumed that almost all components are interconnected. [Explanation of Symbols]

[0086] 100 Network Systems 101A, 101B HSS 102A, 102B PGW·PCEF 103A, 103B Authentication Device 104A, 104B PCRF 105A, 105B OCS 110 IP adapter 111 Adapter Database 112 Address Adapter 200 Mobile network operator A's network 201A, 301B base station equipment 202A, 302B MME 203A, 303B SGW 300 Mobile network operator B's network 400 devices 500 Internet

Claims

1. A communication system connected to two or more mobile carrier networks, A management device is provided corresponding to each of the aforementioned mobile communication carrier networks to manage user information, A gateway device that forwards packets sent and received by a terminal connected to the aforementioned mobile carrier network, and assigns the terminal an address that can be used even if the mobile carrier network to which the terminal is connected changes, The system includes an adapter device that uses addresses recorded in a database managed by the adapter device to forward packets destined for the terminal received from an external network into the mobile carrier network, A communication system characterized in that the terminal records an address assigned by the gateway device and connects to the mobile carrier network using the address recorded in the terminal.

2. A communication system according to claim 1, Each of the identification numbers recorded in the terminal corresponds to each of the aforementioned mobile carrier networks, and each of the aforementioned terminals is assigned a real address, and one virtual address is assigned to each terminal. The adapter device is a communication system characterized by managing the actual address and the virtual address.

3. A communication system according to claim 2, The adapter device is The system manages active information indicating the packet transmission route from the terminal using the aforementioned virtual address. A communication system characterized by determining a route for forwarding packets input from the external network to the terminal by referring to the aforementioned active information.

4. A communication system according to claim 3, The adapter device is a communication system characterized in that, upon receiving a route change request from the terminal, it updates the active information and changes the route for forwarding packets input from the external network to the terminal.

5. A communication system according to claim 3, The adapter device is a communication system characterized in that, upon detecting a change in the packet transmission route from the terminal, it updates the active information and changes the route for forwarding packets input from the external network to the terminal to the detected route.

6. A communication system according to claim 1, The adapter device is The system manages addresses corresponding to identification numbers recorded in the terminal in accordance with the aforementioned mobile communications carrier network, Priority information indicating the packet transmission route to be used preferentially with the aforementioned terminal is managed. Upon receiving a route change request from the terminal, the gateway device is notified of the terminal's address change, the priority information is updated, and the route for forwarding packets received from the external network is changed. A communication system characterized in that the gateway device, upon receiving a notification of address change from the adapter device, notifies the terminal of the address change.

7. A communication control method in a communication system connected to two or more mobile communication carrier networks, The communication system is provided in accordance with each of the mobile carrier networks and includes a management device for managing user information, a gateway device for forwarding packets transmitted and received by terminals connected to the mobile carrier network, and an adapter device for forwarding packets between the mobile carrier network and an external network. The aforementioned method, The gateway device assigns the terminal an address that can be used even if the mobile carrier network to which the terminal is connected changes. The terminal records the address assigned by the gateway device and connects to the mobile carrier network using the address recorded in the terminal. A communication control method characterized in that the adapter device uses an address recorded in a database managed by the adapter device to forward a packet destined for the terminal, received from an external network, to the mobile communications carrier network.

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