Wireless communication system and communication method

Abstract

A wireless communication system (1) comprises a closed system (11) and a cloud system (21). The closed system (11) comprises call control servers (12) that control the communication of wireless stations (41, 42) respectively connected to a closed network (10) and an internet network (20), closed-side gateway servers (13), and a closed-side DNS server (14) that performs name resolution. The same domain name is assigned to a plurality of closed-side gateway servers (13) that are associated with the same call control server (12). The closed-side DNS server (14) selects one among a plurality of closed-side devices corresponding to the same domain name, in accordance with at least one of the route to the wireless station (41) and the operation status, and transmits a name resolution response including the address of the selected closed-side device to the wireless station (41).

Description

Wireless communication system and communication method

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

[0002] In order for communication devices connected to different networks, such as a local area network (LAN) and a wide area network (WAN), to communicate with each other, a gateway device is provided between the different networks. Patent Literature 1 discloses an example of a communication device that communicates with other communication devices connected to different networks via a gateway device.

[0003] The voice communication system disclosed in Patent Document 1 includes a gateway device that connects a LAN and LTE (Long Term Evolution), a mobile phone communication network, and relays communication between a LAN communication terminal connected to the LAN and an LTE communication terminal connected to the LTE.

[0004] International Publication No. 2017 / 006833

[0005] In the voice communication system disclosed in Patent Document 1, if the LTE server breaks down, the LTE communication terminal and the LAN communication terminal cannot communicate with each other.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to improve the availability of a wireless communication system and communication method that enable communication between a wireless station connected to an Internet network and a wireless station connected to a closed network.

[0007] In order to achieve the above object, a wireless communication system according to a first aspect of the present invention comprises a closed system provided in a closed network and a cloud system provided in an Internet network, said closed system and said cloud system being connected to each other so as to be able to communicate with each other, said closed system comprising: at least one call control server each controlling communication between a plurality of wireless stations connected to either said closed network or said Internet network; and a plurality of closed side gateway servers each provided in association with said call control server, each holding an association between said wireless stations and said call control server, and each transmitting, upon receiving a registration request or voice data from a wireless station connected to said closed network, said registration request or voice data to said call control server associated with said wireless station, and transmitting, upon receiving a registration response or voice data from said call control server, said registration response or voice data to said wireless station as a destination; a closed-side DNS server which, when receiving a name resolution request for a domain name of a closed-side device included in the closed system or a cloud-side device included in the cloud system from the wireless station connected to the closed network, performs name resolution of the domain name included in the name resolution request and transmits a name resolution response including an address corresponding to the domain name to the wireless station; the cloud system comprises a cloud-side gateway server which holds correspondence between the wireless station and the call control server, and, when receiving a registration request or voice data from the wireless station connected to the Internet network, transmits the registration request or the voice data to the call control server associated with the wireless station, and, when receiving a registration response or voice data addressed to the wireless station connected to the Internet network from the call control server, transmits the registration response or the voice data to the wireless station; and a management server which acquires the operating status of the closed-side device,When the closed-side DNS server receives the name resolution request from the closed-side device, it selects one of the closed-side devices from the multiple closed-side devices corresponding to the domain name based on at least one of the operating status of the closed-side device and the route to the wireless station acquired by the management server, and transmits the name resolution response including the address of the selected closed-side device to the wireless station.

[0008] Preferably, the same domain name is assigned to the closed-area gateway servers associated with the same call control server.

[0009] Preferably, when the closed-side DNS server receives the name resolution request for the closed-side gateway server, which is the closed-side device, from the wireless station connected to the closed network, it selects one of the closed-side gateway servers corresponding to the domain name included in the name resolution request, depending on at least one of the operating status of each of the closed-side gateway servers and the route to the wireless station, and transmits the name resolution response including the address of the selected closed-side gateway server to the wireless station.

[0010] Preferably, the closed system further includes a plurality of closed-side activation servers that, when receiving an activation request from a wireless station connected to the closed network as the closed-side device, register activation information including specific information that uniquely identifies the wireless station in storage devices provided in each of the closed system and the cloud system.

[0011] Preferably, when the closed-side DNS server receives the name resolution request for the closed-side activation server, which is the closed-side device, from the wireless station connected to the closed network, it selects one of the multiple closed-side activation servers corresponding to the domain name included in the name resolution request, depending on at least one of the operating status of each of the closed-side activation servers and the route to the wireless station, and transmits the name resolution response including the address of the selected closed-side activation server to the wireless station.

[0012] Preferably, the closed system includes a plurality of the closed systems that are communicably connected to each other via the cloud system, and for each of the wireless stations, one of the plurality of closed systems is set as a main closed system, and the other closed systems are set as sub-closed systems, and the same domain name is assigned to the plurality of closed-side gateway servers that correspond to one of the call control servers owned by the main closed system and the plurality of closed-side gateway servers that correspond to one of the call control servers owned by the sub-closed system, and when the closed-side DNS server receives the name resolution request of the closed-side gateway server from the wireless station connected to the closed network, it selects one of the plurality of closed-side gateway servers to which the domain name included in the name resolution request is assigned, depending on at least one of the operation status of the call control server that corresponds to the plurality of closed-side gateway servers to which the domain name included in the name resolution request is assigned, the operation status of the closed-side gateway server, and the route to the wireless station.

[0013] Preferably, when the operation status of the call control server of the main closed system is normal, the closed-side DNS server selects one of the multiple closed-side gateway servers included in the main closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operation status of the multiple closed-side gateway servers associated with the call control server of the main closed system and the route to the radio station, and when the operation status of the call control server of the main closed system is abnormal, the closed-side DNS server selects one of the multiple closed-side gateway servers included in the sub-closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operation status of the multiple closed-side gateway servers associated with the call control server of the sub-closed system and the route to the radio station.

[0014] Preferably, the closed system further has, as the closed side device, a plurality of closed side activation servers that, when receiving an activation request from a wireless station connected to the closed network, register activation information including unique information that uniquely identifies the wireless station in storage devices provided in the closed system and the cloud system, and the same domain name is assigned to at least one of the plurality of closed side activation servers owned by the main closed system and at least one of the plurality of closed side activation servers owned by the sub-closed system, and when the closed side DNS server receives the name resolution request from the closed side activation server from the wireless station connected to the closed network, it selects one of the plurality of closed side activation servers to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the plurality of closed side activation servers to which the domain name included in the name resolution request is assigned and the route to the wireless station.

[0015] Preferably, when the operating status of at least one of the closed-side activation servers owned by the main closed system is normal, the closed-side DNS server selects one of the closed-side activation servers included in the main closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the closed-side activation server owned by the main closed system and the route to the wireless station, and when the operating status of the closed-side activation server owned by the main closed system is abnormal, the closed-side DNS server selects one of the closed-side activation servers included in the sub-closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the closed-side activation server owned by the sub-closed system and the route to the wireless station.

[0016] A communication method according to a second aspect of the present invention is a wireless communication system comprising a closed system provided in a closed network and a cloud system provided in an Internet network, the closed system and the cloud system being connected to each other so as to be able to communicate with each other, the closed system comprising: a call control server that controls communication between a plurality of wireless stations each connected to either the closed network or the Internet network; a plurality of closed-side gateway servers that are provided in correspondence with the call control servers and that hold correspondences between the wireless stations and the call control servers; and a closed-side DNS server that performs name resolution of domain names of closed-side devices included in the closed system or cloud-side devices included in the cloud system, the cloud system comprising: a cloud-side gateway server that holds correspondences between the wireless stations and the call control servers; and a management server that acquires operating statuses of the closed-side devices, the communication method being performed by the wireless communication system, When receiving a registration request or voice data from the wireless station connected to the closed network, the server transmits the registration request or voice data to the call control server associated with the wireless station, and when receiving a registration response or voice data from the call control server, the server transmits the registration response or voice data to the wireless station that is the destination; when receiving a name resolution request for a domain name of a closed side device included in the closed system or a cloud side device included in the cloud system from the wireless station connected to the closed network, the server performs name resolution of the domain name included in the name resolution request and transmits a name resolution response including an address corresponding to the domain name to the wireless station; and when receiving a name resolution request for a domain name of a closed side device included in the cloud system from the wireless station connected to the closed network, the server performs name resolution of the domain name included in the name resolution request and transmits a name resolution response including an address corresponding to the domain name to the wireless station;When a registration request or voice data is received from the wireless station connected to the Internet network, the server transmits the registration request or voice data to the call control server associated with the wireless station, and when a registration response or voice data addressed to the wireless station connected to the Internet network is received from the call control server, the server transmits the registration response or voice data to the wireless station. When the closed-side DNS server receives the name resolution request of the closed-side device, the server selects one of the closed-side devices corresponding to the domain name according to at least one of the acquired operating status of the closed-side device and the route to the wireless station, and transmits the name resolution response including the address of the selected closed-side device to the wireless station.

[0017] When a closed-side DNS server that performs name resolution and is provided in a wireless communication system according to the present invention receives a name resolution request from a closed-side device, it selects one of the closed-side devices corresponding to the domain name based on at least one of the operating status of the closed-side device and the route to the wireless station, and transmits a name resolution response including the address of the selected closed-side device to the wireless station. This makes it possible to relay communication of the wireless station even if one of the closed-side devices fails, thereby improving the availability of the wireless communication system.

[0018] 1 is a block diagram showing the configuration of a wireless communication system according to a first embodiment; 2 is a block diagram showing the configuration of a wireless station according to the first embodiment; 3 is a flowchart showing an example of a startup process performed by a wireless station according to the first embodiment; 4 is a sequence diagram showing an example of a name resolution process performed by a wireless communication system according to the first embodiment; 5 is a diagram showing an example of a relationship between a closed-side gateway server and a call control server in a wireless communication system according to the first embodiment; 6 is a sequence diagram showing an example of a communication establishment process performed by a wireless communication system according to the first embodiment; 7 is a block diagram showing the configuration of a wireless communication system according to a second embodiment;

[0019] A wireless communication system and a communication method according to an embodiment of the present invention will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0020] (First Embodiment) A wireless communication system 1 shown in Fig. 1 relays communications between wireless stations 41, 42, and 43 connected to either a closed network 10 or an Internet network 20. In the first embodiment, the wireless stations 41, 42, and 43 are IP (Internet Protocol) transceivers that perform voice communications. The wireless stations 41, 42, and 43 have the same configuration and function. In the example of Fig. 1, the wireless stations 41 and 43 are connected to the closed network 10 via a base station 31, and the wireless station 42 is connected to the Internet network 20 via a WLAN (Wireless Local Area Network) device 32. The WLAN device 32 is, for example, an access point device.

[0021] The wireless communication system 1 includes a closed system 11 provided in a closed network 10 and a cloud system 21 provided in an Internet network 20. The closed system 11 includes a plurality of call control servers 12, a plurality of closed-side gateway servers 13, a closed-side Domain Name System (DNS) server 14, a plurality of closed-side activation servers 15, a router 16, and a storage device 17. The cloud system 21 includes a plurality of cloud-side gateway servers 22, a plurality of cloud-side provisioning servers 23, a plurality of cloud-side activation servers 24, an endpoint device 25, a dedicated connection device 26, a storage device 27, and a management server 28.

[0022] The closed system 11 and the cloud system 21 are connected to each other via a dedicated line. A dedicated connection device 26 connects each of the cloud-side devices included in the cloud system 21 to the closed-side devices included in the closed system 11 and the closed network 10 via a dedicated line. The closed-side devices are the components of the closed system 11 described above, specifically, the call control server 12, the closed-side gateway server 13, the closed-side DNS server 14, the closed-side activation server 15, the router 16, and the storage device 17. The cloud-side devices are the components of the cloud system 21, specifically, the cloud-side gateway server 22, the cloud-side provisioning server 23, the cloud-side activation server 24, the endpoint device 25, the storage device 27, and the management server 28. Note that the term "devices" refers to not only physically existing devices and devices but also virtual devices and devices.

[0023] The closed system 11 includes two or more call control servers 12. Each call control server 12 controls communications between the wireless stations 41, 42, and 43, specifically, controls calls such as voice transmission and reception.

[0024] The closed system 11 includes two or more closed-side gateway servers 13, each associated with a call control server 12. Each closed-side gateway server 13 holds a correspondence between the wireless stations 41, 43 and the call control server 12. As an example, the closed-side gateway server 13 holds a table that associates unique information that uniquely identifies the wireless stations 41, 43 with the address of the call control server 12. The unique information that uniquely identifies the wireless stations 41, 43 is, for example, an IMEI (International Mobile Equipment Identifier) ​​or an ICCID (Integrated Circuit Card Identifier), which is an identification number of a SIM (Subscriber Identity Module) card inserted in each of the wireless stations 41, 43.

[0025] When the closed-side gateway server 13 receives a registration request or voice data from a wireless station 41 connected to the closed network 10 via the router 16, it transmits the received registration request or voice data to the call control server 12 associated with the wireless station 41. When the closed-side gateway server 13 receives a registration response or voice data from the call control server 12, it transmits the received registration response or voice data to the destination wireless station 41 via the router 16.

[0026] The closed-side DNS server 14 performs name resolution for closed-side devices included in the closed system 11 and for cloud-side devices included in the cloud system 21. The closed-side devices that are the targets of name resolution by the closed-side DNS server 14 are, for example, the closed-side gateway server 13 and the closed-side activation server 15. The cloud-side device that is the target of name resolution by the closed-side DNS server 14 is, for example, the cloud-side activation server 24.

[0027] In detail, when the closed-side DNS server 14 receives a name resolution request for the domain name of a closed-side device included in the closed system 11 or a cloud-side device included in the cloud system 21 from a wireless station 41 connected to the closed network 10, the closed-side DNS server 14 performs name resolution of the domain name included in the name resolution request and transmits a name resolution response including an address corresponding to the domain name to the wireless station 41.

[0028] The closed system 11 includes two or more closed-side activation servers 15. When each closed-side activation server 15 receives an activation request from a wireless station 41, 43 connected to the closed network 10, it registers activation information including unique information of the wireless station 41, 43 in storage devices 17, 27 provided in the closed system 11 and the cloud system 21, respectively.

[0029] The storage device 17 is a DB server, for example, a NoSQL server, that stores activation information.

[0030] The router 16 transfers data received from the cloud system 21 or the closed network 10 to a closed-side device included in the closed system 11 according to the destination of the data.

[0031] The dedicated connection device 26 is, for example, a virtual interface connected to the closed system 11 and the closed network 10 via a dedicated line. The dedicated connection device 26 transmits data received from the closed system 11 or the closed network 10 having the above configuration to cloud-side devices included in the cloud system 21, specifically, to any of the servers in the cloud system 21, namely, the cloud-side gateway server 22, the cloud-side provisioning server 23, the cloud-side activation server 24, and the management server 28, depending on the type of data. The dedicated connection device 26 also transfers data received from cloud-side devices, specifically, from each server in the cloud system 21, to the closed system 11 or the closed network 10.

[0032] As an example, when the dedicated connection device 26 receives a provisioning request from the wireless station 41 via the base station 31 and the closed network 10, it transfers the provisioning request to the cloud-side provisioning server 23 via a load balancer (not shown). In detail, the load balancer transfers the provisioning request to one of the multiple cloud-side provisioning servers 23 depending on at least one of the route to the wireless station 41 and the operating status of each cloud-side provisioning server 23. As an example, the load balancer selects one of the multiple cloud-side provisioning servers 23 in a round-robin manner and transfers the provisioning request to the selected cloud-side provisioning server 23.

[0033] When the dedicated connection device 26 receives the provisioning response from the cloud-side provisioning server 23 via the load balancer, it transmits the provisioning response to the wireless station 41 via the closed network 10 .

[0034] As another example, when the dedicated connection device 26 receives an operation notification sent from a closed-side device included in the closed system 11, specifically, the call control server 12, the closed-side gateway server 13, or the closed-side activation server 15, the dedicated connection device 26 forwards the operation notification to the management server 28.

[0035] The endpoint device 25 is an interface that connects the cloud system 21 and the Internet network 20. The endpoint device 25 transfers data received from the Internet network 20 to cloud-side devices included in the cloud system 21, specifically, to each server in the cloud system 21, depending on the type of data. In particular, the endpoint device 25 transmits the data received from the Internet network 20 to any one of the cloud-side gateway server 22, the cloud-side provisioning server 23, the cloud-side activation server 24, and the management server 28. The endpoint device 25 also transfers data received from cloud-side devices, specifically, from each server in the cloud system 21, to the wireless station 42 via the Internet network 20.

[0036] As an example, when the endpoint device 25 receives a provisioning request from the wireless station 42 via the WLAN device 32 and the Internet network 20, the endpoint device 25 forwards the provisioning request to the cloud-side provisioning server 23 via a load balancer (not shown). In particular, the load balancer forwards the provisioning request to one of the multiple cloud-side provisioning servers 23 depending on at least one of the path to the wireless station 42 and the operating status of each cloud-side provisioning server 23. As an example, the load balancer selects one of the multiple cloud-side provisioning servers 23 in a round-robin manner and forwards the provisioning request to the selected cloud-side provisioning server 23.

[0037] When the endpoint device 25 receives the provisioning response from the cloud-side provisioning server 23 via the load balancer, the endpoint device 25 transmits the provisioning response to the wireless station 42 via the Internet network 20 .

[0038] Each cloud-side gateway server 22 holds a correspondence between the wireless station 42 and the call control server 12. As an example, each cloud-side gateway server 22 holds a table that associates unique information of the wireless station 42 with the address of the call control server 12. The unique information that uniquely identifies the wireless station 42 is, for example, the IMEI, the ICCID that is the identification number of the SIM card inserted in the wireless station 42, or the like.

[0039] When the cloud-side gateway server 22 receives a registration request or voice data from a wireless station 42 connected to the Internet network 20, it transmits the received registration request or voice data to the call control server 12 associated with the wireless station 42. When the cloud-side gateway server 22 receives a registration response or voice data from the call control server 12, it transmits the received registration response or voice data to the wireless station 42 that is the destination.

[0040] When the cloud-side provisioning server 23 receives a provisioning request from the wireless stations 41, 42, and 43, it transmits a provisioning response including the domain name of the gateway server to the wireless stations 41, 42, and 43.

[0041] When the cloud-side activation server 24 receives an authentication request from a wireless station 42 connected to the Internet network 20, the activation information including the wireless station 42's unique information and encryption key generation information is stored in a storage device provided in at least one of the closed system 11 and the cloud system 21, for example, in storage devices 17 and 27 provided in the closed system 11 and the cloud system 21, respectively.

[0042] The storage device 27 is a DB server, for example, a NoSQL server, that stores activation information and the operating status of the closed-side devices and cloud-side devices.

[0043] The management server 28 acquires information about the closed-side devices. It is preferable that the management server 28 also acquires information about the cloud-side devices. Specifically, the management server 28 receives operation notifications periodically sent from each call control server 12, each closed-side gateway server 13, each closed-side activation server 15, each cloud-side gateway server 22, each cloud-side provisioning server 23, and each cloud-side activation server 24. The management server 28 stores the operation notifications of the closed-side devices and cloud-side devices acquired as described above in the storage device 27. If operation notifications are periodically received, the operating status of the closed-side device or cloud-side device that sent the operation notifications can be considered normal. If a state in which no operation notifications can be received from the closed-side device or cloud-side device continues for a certain period of time, the operating status of the closed-side device or cloud-side device that has not sent the operation notification can be considered abnormal. In other words, the storage device 27 stores information indicating whether the operating status of the closed-side device and cloud-side device is normal or abnormal.

[0044] 2 shows the configuration of wireless stations 41, 42, and 43 that communicate via the wireless communication system 1 having the above configuration. Each of the wireless stations 41, 42, and 43 includes an LTE communication circuit 51, a WLAN communication circuit 52, a communication control circuit 53, a data processing circuit 54, an input circuit 55, and an output circuit 56. The LTE communication circuit 51 connects to the closed network 10 and transmits and receives closed network data that conforms to the communication standard of the closed network 10. The WLAN communication circuit 52 connects to the Internet network 20 via the WLAN device 32 and transmits and receives communication data that conforms to the communication standard of the Internet network 20. The communication control circuit 53 controls the LTE communication circuit 51 and the WLAN communication circuit 52 to establish voice communication.

[0045] The data processing circuit 54 generates, from the transmission data generated by the input circuit 55, closed network data to be transmitted from the LTE communication circuit 51 or communication data to be transmitted from the WLAN communication circuit 52. The data processing circuit 54 also generates reception data from the closed network data received by the LTE communication circuit 51 or the communication data received by the WLAN communication circuit 52, and outputs the reception data to the output circuit 56.

[0046] The input circuit 55 acquires audio from a microphone (not shown), performs signal processing such as A-D (Analog-to-Digital) conversion, noise filtering, and amplification, generates data to be transmitted, and sends the generated data to the data processing circuit 54.

[0047] The output circuit 56 performs signal processing such as noise filtering, amplification, and D-A (Digital-to-Analog) conversion on the received data acquired from the data processing circuit 54 to generate audio data, and outputs the generated audio data from a speaker (not shown). The output circuit 56 may also acquire processing results such as activation, provisioning, and registration from the data processing circuit 54 and display them on a screen (not shown).

[0048] When the wireless stations 41, 42, and 43 having the above configuration are started, for example, when the power is turned on, the start-up process shown in Fig. 3 is initiated. By performing the start-up process, the wireless stations 41, 42, and 43 can start voice communication.

[0049] Since the startup processes performed by the wireless stations 41 and 43 connected to the closed network 10 are similar, the startup process performed by the wireless station 41 will be described below. The wireless station 41 performs name resolution for the closed-side activation server 15 in order to set up the wireless station 41 when it starts using the network (step S11).

[0050] The details of the name resolution process performed by the wireless station 41 are shown in Figure 4. The wireless station 41 transmits a name resolution request including the domain name of the closed-side activation server 15, which is the destination of the activation request, to the closed-side DNS server 14 (sequence Sq1). Specifically, the wireless station 41 sets its own IP address as the source IP address and the IP address of the closed-side DNS server 14 as the destination IP address, and generates and transmits the name resolution request including the domain name of the closed-side activation server 15. It is assumed that the wireless station 41 already holds the IP address of the closed-side DNS server 14. The name resolution request transmitted from the wireless station 41 reaches the closed-side DNS server 14 via the base station 31, the closed network 10, and the router 16.

[0051] When the closed-side DNS server 14 receives the name resolution request including the domain name of the closed-side activation server 15, it sends an operation status acquisition request for each closed-side activation server 15 to the storage device 27 (sequence Sq2). The operation status acquisition request reaches the storage device 27 via the router 16 and the dedicated connection device 26.

[0052] When the storage device 27 receives the request to obtain the operating status of the closed-side activation servers 15, it reads out the operating status of each closed-side activation server 15 and transmits an operating status response including information indicating the operating status to the closed-side DNS server 14 (sequence Sq3). The operating status response transmitted from the storage device 27 reaches the closed-side DNS server 14 via the dedicated connection device 26 and the router 16.

[0053] The closed-side DNS server 14 selects a closed-side activation server 15 to which the activation request is to be sent, based on at least one of the operating status of each closed-side activation server 15 and the route to the wireless station 41, which are acquired from the storage device 27 (sequence Sq4). As an example, the closed-side DNS server 14 selects one of the closed-side activation servers 15, which are operating normally, based on a round-robin method.

[0054] The closed-side DNS server 14 transmits a name resolution response including the address of the selected closed-side activation server 15 to the wireless station 41 (sequence Sq5). In detail, the closed-side DNS server 14 sets its own IP address as the source IP address and the source IP address of the name resolution request as the destination IP address, and generates and transmits the name resolution response including the address of the selected closed-side activation server 15. The name resolution response transmitted from the closed-side activation server 15 reaches the wireless station 41 via the router 16, the closed network 10, and the base station 31.

[0055] 3, after completing the name resolution process in step S11, the wireless station 41 performs activation processing with the closed-side activation server 15 (step S12). In step S12, the wireless station 41 transmits an activation request to the closed-side activation server 15. In response to the activation request from the wireless station 41, the closed-side activation server 15 registers activation information including unique information of the wireless station 41 in the storage devices 17 and 27. After completing the registration of the activation information, the closed-side activation server 15 transmits a notification to the wireless station 41 indicating that the activation has been successfully completed.

[0056] For example, if neither the storage device 17 nor the storage device 27 can be accessed and the registration of the activation information is not completed normally, the closed-side activation server 15 sends an error notification, for example, a notification that the activation has been canceled, to the wireless station 41.

[0057] When the activation process does not end normally (step S13; No), for example, when an error notification is received from the closed-side activation server 15, the wireless station 41 displays on the screen that an error has occurred (step S23).

[0058] When the activation process has been completed successfully (step S13; Yes), the wireless station 41 performs name resolution of the cloud-side provisioning server 23 in order to perform provisioning process for acquiring connection information (step S14). In the name resolution process in step S14, only sequences Sq1 and Sq5 in Fig. 4 are executed. In sequence Sq1, the wireless station 41 transmits a name resolution request to the closed-side DNS server 14, the name resolution request including the domain names of the load balancers connected to the multiple cloud-side provisioning servers 23, which are destinations of the provisioning request.

[0059] In sequence Sq5, the closed-side DNS server 14 transmits a name resolution response including the address of the load balancer to the wireless station 41.

[0060] 3, after completing the name resolution process in step S14, the wireless station 41 performs a provisioning process on the cloud-side provisioning server 23 (step S15). In step S15, the wireless station 41 generates a provisioning request in which the address of the load balancer is set as the destination IP address. The provisioning request sent by the wireless station 41 reaches the cloud-side provisioning server 23 via the base station 31, the closed network 10, the dedicated connection device 26, and the load balancer.

[0061] When the cloud-side provisioning server 23 receives the provisioning request, it extracts the unique information of the wireless station 41 included in the provisioning request and acquires the activation information of the wireless station 41 from the storage device 27. Based on the acquired activation information, the cloud-side provisioning server 23 performs a check to determine whether the activation of the wireless station 41 has been performed normally.

[0062] If activation is performed successfully, the cloud-side provisioning server 23 sends a provisioning response addressed to the wireless station 41, including connection information for connecting to the call control server 12 corresponding to the wireless station 41, to the dedicated connection device 26 via the load balancing device.

[0063] When the load balancer receives the provisioning response, it transfers the provisioning response to the destination wireless station 41 via the dedicated connection device 26. The provisioning response sent from the cloud-side provisioning server 23 reaches the wireless station 41 via the load balancer, the dedicated connection device 26, the closed network 10, and the base station 31.

[0064] For example, if the cloud-side provisioning server 23 cannot access the storage device 27 and cannot acquire the activation information, the cloud-side provisioning server 23 transmits an error notification to the load balancer addressed to the wireless station 41. Upon receiving the error notification, the load balancer forwards the error notification to the wireless station 41 via the dedicated connection device 26.

[0065] When the provisioning process has not been completed successfully (step S16; No), for example, when an error notification is received from the cloud-side provisioning server 23 or when the wireless station 41 is unable to connect to the cloud-side provisioning server 23, the wireless station 41 determines whether or not previous information, which is connection information acquired the previous time the wireless station 41 performed startup processing, is available (step S17). If previous information is not available (step S17; No), the wireless station 41 displays on the screen a message indicating that an error has occurred (step S23).

[0066] When the provisioning process did not end normally but previous information exists (step S16; No, step S17; Yes), or when the provisioning process ended normally (step S16; Yes), the wireless station 41 reflects the connection information or previous information acquired in step S15 as connection information in its own device (step S18).

[0067] Next, the wireless station 41 performs name resolution with the closed-side gateway server 13 in order to register its own information with the call control server 12. Figure 5 shows an example of the relationship between the call control server 12 and the closed-side gateway server 13. Figure 5 shows the call control server 12 and the closed-side gateway server 13, which are components of the closed system 11. The call control servers 12 shown in Figure 5 are distinguished as call control servers 121 and 122, and the closed-side gateway servers 13 are distinguished as closed-side gateway servers 131, 132, 133, 134, 135, and 136. The call control server 121 is associated with the closed-side gateway servers 131, 132, and 133. The call control server 122 is associated with the closed-side gateway servers 134, 135, and 136.

[0068] The same domain name is assigned to the closed-side gateway servers 13 associated with the same call control server 12. In other words, the same domain name, for example, gw1, is assigned to the closed-side gateway servers 131, 132, and 133 associated with the call control server 121. Different addresses are assigned to the closed-side gateway servers 131, 132, and 133. Similarly, the same domain name, for example, gw2, is assigned to the closed-side gateway servers 134, 135, and 136 associated with the call control server 122. Different addresses are assigned to the closed-side gateway servers 134, 135, and 136.

[0069] The wireless stations 41, 42, and 43 are associated with one of the call control servers 12 and register with the associated call control server. As an example, it is assumed that the wireless stations 41 and 42 are associated with the call control server 121, and the wireless station 43 is associated with the call control server 122. In other words, when the call control server 121 accepts the registration of the wireless stations 41 and 42, it controls the calls of the wireless stations 41 and 42, whether they are making or receiving calls. Similarly, when the call control server 122 accepts the registration of the wireless station 43, it controls the calls of the wireless station 43, whether they are making or receiving calls.

[0070] The wireless station 41 registers with the call control server 121 via one of the closed-side gateway servers 131-133. In detail, as shown in Fig. 3, the wireless station 41 requests the closed-side DNS server 14 to perform name resolution for one of the closed-side gateway servers 131-133 (step S19). The operation of the name resolution process performed by the wireless station 41 in step S19 is the same as that shown in Fig. 4. In sequence Sq1, the wireless station 41 transmits a name resolution request to the closed-side DNS server 14, including the domain name, for example, gw1, of the closed-side gateway server 131-133 that is the destination of the registration request.

[0071] In sequence Sq2, the closed-side DNS server 14 sends an operation status acquisition request for the closed-side gateway servers 131-133 to the storage device 27. In sequence Sq3, the storage device 27 sends an operation status response including information about the operation status of the closed-side gateway servers 131-133 to the closed-side DNS server 14.

[0072] In sequence Sq4, the closed-side DNS server 14 selects the closed-side gateway server 13 to be the destination of the registration request, depending on at least one of the operating status of the closed-side gateway servers 131-133 and the route to the wireless station 41, which are obtained from the storage device 27. As an example, the closed-side DNS server 14 selects one of the closed-side gateway servers 131-133 in a round-robin manner from those with normal operating status. For example, it is assumed that the closed-side DNS server 14 selects the closed-side gateway server 131.

[0073] In sequence Sq 5 , the closed-side DNS server 14 transmits a name resolution response including the address of the selected closed-side gateway server 131 to the wireless station 41 .

[0074] 3, after completing the name resolution process in step S19, the wireless station 41 performs registration processing with the closed-side gateway server 131 (step S20). In step S20, the wireless station 41 transmits a registration request to the closed-side gateway server 131. Specifically, the wireless station 41 sets its own IP address as the source IP address and the address of the closed-side gateway server 131 included in the name resolution response as the destination IP address, and generates and transmits a registration request including information unique to the wireless station 41. The registration request transmitted from the wireless station 41 reaches the closed-side gateway server 131 via the base station 31, the closed network 10, and the router 16.

[0075] When the closed-side gateway server 131 receives the registration request, it transmits the registration request, including the unique information of the wireless station 41, to the call control server 121 corresponding to the wireless station 41. The closed-side gateway server 131 stores the sender address of the registration request and the unique information of the wireless station 41 included in the registration request in association with each other.

[0076] Upon receiving the registration request, the call control server 121 transmits a registration response including the unique information of the wireless station 41 to the closed-area gateway server 131 that has sent the registration request.

[0077] Upon receiving the registration response, the closed-side gateway server 131 transmits the registration response to the wireless station 41. In detail, the closed-side gateway server 131 sets the IP address of its own device as the source IP address and sets the IP address associated with the unique information of the wireless station 41 included in the registration response received from the call control server 121 as the destination IP address, and then generates and transmits the registration response. The registration response transmitted from the closed-side gateway server 131 reaches the wireless station 41 via the router 16, the closed network 10, and the base station 31.

[0078] 3, when the registration process is not completed normally (step S21; No), for example, when the wireless station 41 does not receive a registration response from the closed-side gateway server 131 within a certain period of time, the wireless station 41 displays a message on the screen indicating that an error has occurred (step S23). The certain period of time may be determined based on the time required for receiving a registration response after transmitting a registration request under normal circumstances, the length of allowable downtime, etc.

[0079] When the registration process is completed normally (step S21; Yes), specifically, when the wireless station 41 receives a registration response from the closed-side gateway server 131, the wireless station 41 displays on its screen a message indicating that the startup process has been completed normally (step S22). When the process of displaying on its screen the message indicating that the startup process has been completed normally in step S22 is completed, the wireless station 41 becomes able to start voice communication. When steps S22 and S23 are completed, the wireless station 41 ends the startup process.

[0080] The wireless station 43 performs startup processing in the same manner as the wireless station 41. The wireless station 43 registers with the call control server 122 via one of the closed-side gateway servers 134-136. More specifically, in step S19, the wireless station 43 requests the closed-side DNS server 14 to perform name resolution for one of the closed-side gateway servers 134-136. The operation of the name resolution processing performed by the wireless station 43 in step S19 is the same as that shown in FIG. 4. In sequence Sq1, the wireless station 43 transmits a name resolution request to the closed-side DNS server 14, the name resolution request including the domain name, for example, gw2, of the closed-side gateway server 134-136 that is the destination of the registration request.

[0081] The startup processing of the wireless station 42 is also the same as that shown in Fig. 3. In the name resolution of steps S11, S14, and S19, the wireless station 42 transmits a name resolution request including the domain name of the endpoint device 25 to an Internet DNS server on the Internet network 20 (not shown in Fig. 1). Upon receiving the name resolution request including the domain name of the endpoint device 25, the Internet DNS server transmits a name resolution response including the address of the endpoint device 25 to the wireless station 42. The wireless station 42 may transmit an activation request, a provisioning request, or a registration request to the endpoint device 25.

[0082] When the endpoint device 25 receives an activation request, a provisioning request, or a registration request, it forwards the request according to the type of the received request. Specifically, the endpoint device 25 forwards an activation request to the cloud-side activation server 24, a provisioning request to the cloud-side provisioning server 23 via a load balancer, and a registration request to the cloud-side gateway server 22.

[0083] When transferring an activation request or registration request, the endpoint device 25 acquires the operating status of each destination server from the storage device 27 and selects a destination server based on the operating status. Specifically, the endpoint device 25 selects one of multiple cloud-side activation servers 24 based on the operating status of each cloud-side activation server 24. For example, the endpoint device 25 uses a round-robin method to select a cloud-side activation server 24 to which the activation request will be transferred from among cloud-side activation servers 24 whose operating status is normal. The endpoint device 25 transfers the activation request to the selected cloud-side activation server 24.

[0084] The endpoint device 25 acquires the operating status of each cloud-side gateway server 22 to which the registration request is to be transferred from the storage device 27, and selects one of the cloud-side gateway servers 22 according to the operating status. As an example, the endpoint device 25 selects, using a round-robin method, the cloud-side gateway server 22 to which the registration request is to be transferred from among the cloud-side gateway servers 22 whose operating status is normal. The endpoint device 25 transfers the registration request to the selected cloud-side gateway server 22.

[0085] The endpoint device 25 transfers the provisioning request to the load balancer. The load balancer selects one of the cloud-side provisioning servers 23 according to the operating status of each cloud-side provisioning server 23. As an example, the load balancer uses a round-robin method to select a cloud-side provisioning server 23 to which the provisioning request is to be transferred from among the cloud-side provisioning servers 23 whose operating status is normal. The load balancer transfers the provisioning request to the selected cloud-side provisioning server 23.

[0086] When the startup processing of the wireless stations 41-43 is completed as described above, voice communication becomes possible between the wireless stations 41-43. As an example, Fig. 6 shows an example in which the wireless station 41 requests a call with the wireless station 42. The wireless station 41 sends a call request to the closed-side gateway server 131, with the wireless station 42 as the destination, specifically, a call request including the ID of the wireless station 42 as the destination ID (sequence Sq11). Upon receiving the call request, the closed-side gateway server 131 transmits the call request to the call control server 121 (sequence Sq12).

[0087] The call control server 121 maintains a correspondence between the callee ID and the closed-side gateway server 131 or the cloud-side gateway server 22. Because the called wireless station 42 is connected to the Internet network 20, the wireless station 42 is associated with the cloud-side gateway server 22. Therefore, upon receiving the above-mentioned call request, the call control server 121 transmits a call request addressed to the cloud-side gateway server 22 corresponding to the called wireless station 42 to the dedicated connection device 26 (sequence Sq13). The call request reaches the dedicated connection device 26 from the call control server 121 via the router 16. Upon receiving the call request, the dedicated connection device 26 forwards the call request to the cloud-side gateway server 22, which is the destination (sequence Sq14).

[0088] When cloud-side gateway server 22 receives the call request, it transmits the call request addressed to wireless station 42, which is the destination of the call, to endpoint device 25 (sequence Sq15). When endpoint device 25 receives the call request, it transfers the call request to destination wireless station 42 via Internet network 20 and WLAN device 32 (sequence Sq16).

[0089] Upon receiving the call request, the wireless station 42 generates a call response addressed to the wireless station 41 that sent the call request and transmits the call response to the endpoint device 25 (sequence Sq17). Upon receiving the call response, the endpoint device 25 transfers the call response to the cloud-side gateway server 22 (sequence Sq18). Upon receiving the call response addressed to the wireless station 41, the cloud-side gateway server 22 transmits the call response addressed to the call control server 121 associated with the wireless station 41 to the dedicated connection device 26 (sequence Sq19). Upon receiving the call response, the dedicated connection device 26 transfers the call response to the call control server 121 that is the destination (sequence Sq20).

[0090] When the call control server 121 receives the call response, it transmits the call response to the closed-side gateway server 131 associated with the destination wireless station 41 (sequence Sq21). When the closed-side gateway server 131 receives the call response, it transmits the call response to the destination wireless station 41 (sequence Sq22). Establishing the call session as described above enables voice communication between the wireless stations 41 and 42. Voice data transfer is also performed in the same manner as in FIG. 6.

[0091] As described above, in the wireless communication system 1 according to the first embodiment, the closed-side DNS server 14 selects one of the closed-side devices corresponding to the domain name included in the name resolution request according to the operating status of the closed-side device. This distributes the load on the closed-side devices, thereby increasing the availability of the wireless communication system 1.

[0092] When the wireless stations 41 and 43 are connected to the Internet network 20, they operate in the same manner as the wireless station 42 described above. When the wireless station 42 is connected to the closed network 10, they operate in the same manner as the wireless station 41 described above. As a result, the wireless stations 41-43 can connect to the call control server 12 and communicate with other wireless stations regardless of whether they are connected to the closed network 10 or the Internet network 20. In other words, the call control server 12 controls the communications of the associated wireless stations 41-43 regardless of whether they are connected to the closed network 10 or the Internet network 20.

[0093] The wireless communication system 1 according to the first embodiment can be modified in various ways in addition to those described above. First, the method by which the closed-side DNS server 14 selects one of the closed-side devices corresponding to the domain name included in the name resolution request is not limited to the round-robin method, and any method can be used as long as it can distribute the load based on the operating status of the closed-side device. The same applies to the load distribution device provided in the cloud system 21.

[0094] Second, the management server 28 may inquire at regular intervals about the operation status of each of the closed-side devices and the cloud-side devices. The management server 28 stores the inquired operation status of each of the closed-side devices and the cloud-side devices in the storage device 27.

[0095] 7, a wireless communication system 2 according to the second embodiment includes a closed system 11a provided in a closed network 10a, a closed system 11b provided in a closed network 10b, and a cloud system 21.

[0096] The configurations of the closed systems 11a and 11b are similar to that of the closed system 11 included in the wireless communication system 1 according to embodiment 1. Specifically, the closed system 11a includes a call control server 12a, a closed-side gateway server 13a, a closed-side DNS server 14a, a closed-side activation server 15a, a router 16a, and a storage device 17a. The closed system 11b includes a call control server 12b, a closed-side gateway server 13b, a closed-side DNS server 14b, a closed-side activation server 15b, a router 16b, and a storage device 17b.

[0097] The cloud system 21 has a configuration different from that of the cloud system 21 provided in the wireless communication system 1 according to the first embodiment, and includes dedicated connection devices 26a and 26b corresponding to the closed systems 11a and 11b, respectively. Specifically, the dedicated connection device 26a connects each of the cloud-side devices included in the cloud system 21 to the closed-side devices included in the closed system 11a and the closed network 10a via dedicated lines. The dedicated connection device 26b connects each of the cloud-side devices included in the cloud system 21 to the closed-side devices included in the closed system 11b and the closed network 10b via dedicated lines.

[0098] The wireless stations 41a, 41b, and 42 can perform voice communication with each other via the wireless communication system 2. The startup processing performed by the wireless stations 41a, 41b, and 42 is the same as that in the first embodiment. The wireless stations 41a and 41b are associated with the closed systems 11a and 11b, respectively.

[0099] For each of the wireless stations 41a, 41b, and 42, one of the closed systems 11a and 11b is set as a main closed system, and the other closed system is set as a sub-closed system. In the second embodiment, for the wireless stations 41a and 42, the closed system 11a is set as the main closed system, and the closed system 11b is set as the sub-closed system. For the wireless station 41b, the closed system 11b is set as the main closed system, and the closed system 11a is set as the sub-closed system.

[0100] The same domain name is assigned to multiple closed-side gateway servers 13a associated with any of the call control servers 12a included in the closed system 11a and multiple closed-side gateway servers 13b associated with any of the call control servers 12b included in the closed system 11b. Similarly, the same domain name is assigned to at least one of the closed-side activation servers 15a included in the closed system 11a and at least one of the closed-side activation servers 15b included in the closed system 11b.

[0101] When the wireless station 41a performs startup processing and is unable to connect to the closed-side gateway server 13a or the closed-side activation server 15a included in the main closed system, the closed-side DNS server 14a performs name resolution so that the wireless station 41a connects to the closed-side gateway server 13b or the closed-side activation server 15b included in the sub-closed system.

[0102] When the wireless station 41b performs startup processing and is unable to connect to the closed-side gateway server 13b or the closed-side activation server 15b, the closed-side DNS server 14b performs name resolution so that the wireless station 41b connects to the closed-side gateway server 13a or the closed-side activation server 15a.

[0103] Since the operations of the closed-side DNS servers 14a and 14b are similar, only the operation of the closed-side DNS server 14a will be described.Details of the server selection process by the closed-side DNS server 14a in sequence Sq4 of FIG.

[0104] In the name resolution of the activation server, the closed-side DNS server 14a acquires the operating status of each closed-side activation server 15a, 15b to which the same domain name is assigned from the storage device 27, and determines whether the operating status of the closed-side activation server 15a, which is the main server, is normal based on the acquired operating status (step S31). If each closed-side activation server 15a is normal (step S31; Yes), the closed-side DNS server 14a acquires a list of main servers by reading the addresses of each closed-side activation server 15a from a memory (not shown) (step S32).

[0105] If an abnormality occurs in each closed-side activation server 15a (step S31; No), the closed-side DNS server 14a obtains a list of sub-servers by reading the addresses of each closed-side activation server 15b from a memory not shown (step S33).

[0106] The closed-side DNS server 14a selects one of the servers from the list of main servers acquired in step S32 or the list of sub-servers acquired in step S33 (step S34). As an example, the closed-side DNS server 14a selects one of the servers from the list of main servers or the list of sub-servers based on a round-robin method. In detail, the closed-side DNS server 14a selects one of the servers from the list of main servers or the list of sub-servers based on the route to the wireless station 41a, specifically, so as to provide the shortest route to the wireless station 41a. When the process of step S34 is completed, the closed-side DNS server 14a terminates the server selection process and transmits a name resolution response including the address of the server selected in step S34 to the wireless station 41a.

[0107] The closed-side DNS server 14a performs similar processing during name resolution at activation. More specifically, in gateway server name resolution, the closed-side DNS server 14a acquires from the storage device 27 the operating status of each closed-side gateway server 13a, 13b to which the same domain name is assigned, and determines whether the operating status of the main server, the closed-side gateway server 13a, is normal based on the acquired operating status (step S31). If the operating status of each closed-side gateway server 13a is normal (step S31; Yes), the closed-side DNS server 14a acquires a list of main servers by reading the addresses of each closed-side gateway server 13a from a memory (not shown) (step S32).

[0108] If an abnormality occurs in each closed-side gateway server 13a (step S31; No), the closed-side DNS server 14a obtains a list of sub-servers by reading the addresses of each closed-side gateway server 13b from a memory (not shown) (step S33).

[0109] The closed-side DNS server 14a selects one of the servers from the list of main servers acquired in step S32 or the list of sub-servers acquired in step S33 (step S34). As an example, the closed-side DNS server 14a selects one of the servers from the list of main servers or the list of sub-servers based on a round-robin method. The closed-side DNS server 14a also selects one of the servers from the list of main servers or the list of sub-servers based on the route to the wireless station 41a. In detail, the closed-side DNS server 14a selects the server from the list of main servers or the list of sub-servers that has the shortest route to the wireless station 41a. When the process of step S34 is completed, the closed-side DNS server 14a ends the server selection process and transmits a name resolution response including the address of the server selected in step S34 to the wireless station 41a.

[0110] As described above, the closed-side DNS servers 14a and 14b included in the wireless communication system 2 according to the second embodiment select one of the servers from the list of main servers or the list of sub-servers to perform name resolution, thereby enabling the wireless stations 41a, 41b, and 42 to continue communication even if an abnormality occurs in the main server. As a result, a wireless communication system 2 with high availability is obtained.

[0111] The wireless communication system 2 according to the second embodiment can be modified in various ways other than those described above. First, the number of closed systems is not limited to the above example, but may be any natural number equal to or greater than two.

[0112] Second, when the closed-side DNS servers 14a and 14b receive a name resolution request from the wireless stations 41a and 41b, they may identify an address corresponding to the domain name based on the route to the wireless stations 41a and 41b. Specifically, they may select a server with the shortest route to the wireless stations 41a and 41b, specifically, a server in a normal operating state that is included in the closed systems 11a and 11b to which the wireless stations 41a and 41b are connected via the closed network 10. The route to the wireless stations 41a and 41b can be identified by identifying whether the wireless stations 41a, 41b, and 42 are connected to the closed systems 11a and 11b or the cloud system 21 from the IP addresses of the wireless stations 41a and 41b, which are the source IP addresses of the name resolution request.

[0113] The modifications described in the first embodiment can also be applied to the second embodiment. Specifically, firstly, the method by which the closed-side DNS server 14 selects one of the closed-side devices from among the multiple closed-side devices corresponding to the domain name included in the name resolution request is not limited to the round-robin method, but may be any method that can distribute the load based on the operating status of the closed-side devices. The same applies to the load distribution device provided in the cloud system 21.

[0114] Second, the management server 28 may inquire at regular intervals about the operation status of each of the closed-side devices and the cloud-side devices. The management server 28 stores the inquired operation status of each of the closed-side devices and the cloud-side devices in the storage device 27.

[0115] An example of a hardware configuration for realizing the above-described wireless communication systems 1 and 2 is shown in Fig. 9. The closed-side devices included in the closed systems 11, 11a, and 11b and the cloud-side devices included in the cloud system 21 are realized by a processor 61, a memory 62, and an interface 63. The processor 61, the memory 62, and the interface 63 are connected to one another by a bus 60. The processor 61 includes any electronic circuit including a transistor, and is considered to be a circuit or a processor circuit.

[0116] For example, the functions of the closed-side devices of the closed systems 11, 11a, and 11b and the cloud-side devices of the cloud system 21 are realized by software, firmware, which is software embedded in electronic devices, or a combination of software and firmware. The software is written as a program and stored in the memory 62. The processor 61 executes the program stored in the memory 62 to realize the functions of the above-mentioned parts. That is, the memory 62 stores programs for executing the processes of the closed-side devices of the closed systems 11, 11a, and 11b and the cloud-side devices of the cloud system 21.

[0117] The memory 62 includes, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read-Only Memory), magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD (Digital Versatile Disc), etc.

[0118] For example, the interface 63 connects the closed systems 11, 11a, and 11b to the cloud system 21 or the wireless stations 41, 41a, 41b, and 43, and connects the cloud system 21 to the wireless station 42, thereby establishing voice communication. The interface 63 has multiple types of interface modules as necessary.

[0119] 9 illustrates one processor 61 and one memory 62, the closed-side devices of the closed systems 11, 11a, and 11b and the cloud-side devices of the cloud system 21 may be realized by a plurality of processors 61 and a plurality of memories 62. In this case, the plurality of processors 61 and the plurality of memories 62 may cooperate with each other to execute the functions of the devices of the closed systems 11, 11a, and 11b and the cloud system 21.

[0120] Each device of the closed systems 11, 11a, and 11b and the cloud system 21 may be realized by a processing circuit 71, as shown in Fig. 10. The processing circuit 71 is connected to other devices via an interface circuit 72.

[0121] When the processing circuitry 71 is dedicated hardware, the processing circuitry 71 includes, for example, a single circuit, a composite circuit, a processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The closed-side devices of the closed systems 11, 11a, and 11b and the cloud-side devices of the cloud system 21 may be realized by any number of processing circuits 71.

[0122] Some of the functions of the closed-side devices of the closed systems 11, 11a, and 11b and the cloud-side devices of the cloud system 21 may be realized by dedicated hardware, and other functions may be realized by software or firmware. For example, in the closed system 11, the call control server 12, the closed-side gateway server 13, the closed-side DNS server 14, and the closed-side activation server 15 may be realized by the processor 61 shown in Fig. 9 reading and executing programs stored in the memory 62, and the router 16 and the storage device 17 may be realized by the processing circuit 71 shown in Fig. 10.

[0123] Furthermore, the above-described hardware configuration and flowchart are merely examples and can be changed and modified as desired.

[0124] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to explain the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0125] This application is based on Japanese Patent Application No. 2024-118877, filed on July 24, 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-118877 are incorporated herein by reference.

[0126] 1, 2 Wireless communication system 10, 10a, 10b Closed network 11, 11a, 11b Closed system 12, 12a, 12b, 121, 122 Call control server 13, 13a, 13b, 131, 132, 133, 134, 135, 136 Closed-side gateway server 14, 14a, 14b Closed-side DNS server 15, 15a, 15b Closed-side activation server 16, 16a, 16b Router 17, 17a, 17b, 27 Storage device 20 Internet network 21 Cloud system 22 Cloud-side gateway server 23 Cloud-side provisioning server 24 Cloud-side activation server 25 Endpoint device 26, 26a, 26b Dedicated connection device 28 Management server 31 Base station 32 WLAN device 41, 41a, 41b, 42, 43 Wireless station 51 LTE communication circuit 52 WLAN communication circuit 53 Communication control circuit 54 Data processing circuit 55 Input circuit 56 Output circuit 60 Bus 61 Processor 62 Memory 63 Interface 71 Processing circuit 72 Interface circuit

Claims

1. A wireless communication system comprising a closed system provided in a closed network and a cloud system provided in an Internet network, said closed system and said cloud system being connected to each other so as to be able to communicate with each other, said closed system comprising: at least one call control server that controls communication between a plurality of wireless stations each connected to either said closed network or said Internet network; a plurality of closed-side gateway servers that are provided in correspondence with said call control server, that maintain correspondence between said wireless stations and said call control server, and that, upon receiving a registration request or voice data from a wireless station connected to said closed network, transmit said registration request or voice data to said call control server associated with said wireless station, and, upon receiving a registration response or voice data from said call control server, transmit said registration response or voice data to said wireless station as a destination; and a closed-side DNS server that, upon receiving a name resolution request for a domain name of a closed-side device included in said closed system or a cloud-side device included in said cloud system from said wireless station connected to said closed network, performs name resolution of the domain name included in the name resolution request, and transmits a name resolution response including an address corresponding to the domain name to said wireless station, the cloud system comprises a cloud-side gateway server that holds correspondence between the wireless stations and the call control servers, and that, upon receiving a registration request or voice data from the wireless station connected to the Internet network, transmits the registration request or voice data to the call control server that is associated with the wireless station, and, upon receiving a registration response or voice data addressed to the wireless station connected to the Internet network from the call control server, transmits the registration response or voice data to the wireless station; and a management server that acquires the operating status of the closed-area device,When the closed-side DNS server receives the name resolution request from the closed-side device, it selects one of the closed-side devices from the multiple closed-side devices corresponding to the domain name, depending on at least one of the operating status of the closed-side device and the route to the wireless station acquired by the management server, and transmits the name resolution response including the address of the selected closed-side device to the wireless station.

2. The wireless communication system according to claim 1, wherein the same domain name is assigned to the multiple closed-area gateway servers associated with the same call control server.

3. The wireless communication system according to claim 2, wherein when the closed-side DNS server receives the name resolution request of the closed-side gateway server, which is the closed-side device, from the wireless station connected to the closed network, it selects one of the closed-side gateway servers corresponding to the domain name included in the name resolution request depending on at least one of the operating status of each of the closed-side gateway servers and the route to the wireless station, and transmits the name resolution response including the address of the selected closed-side gateway server to the wireless station.

4. A wireless communication system according to any one of claims 1 to 3, wherein the closed system further comprises a plurality of closed-side activation servers that, when receiving an activation request from a wireless station connected to the closed network as the closed-side device, register activation information including specific information that uniquely identifies the wireless station in storage devices provided in the closed system and the cloud system, respectively.

5. The wireless communication system described in claim 4, wherein when the closed-side DNS server receives the name resolution request from the closed-side activation server, which is the closed-side device, from the wireless station connected to the closed network, it selects one of the multiple closed-side activation servers corresponding to the domain name included in the name resolution request depending on at least one of the operating status of each of the closed-side activation servers and the route to the wireless station, and transmits the name resolution response including the address of the selected closed-side activation server to the wireless station.

6. A wireless communication system according to any one of claims 1 to 5, comprising a plurality of the closed systems connected to each other so as to be able to communicate with each other via the cloud system, wherein for each of the wireless stations, one of the plurality of closed systems is set as a main closed system and the other closed systems are set as sub-closed systems, the same domain name is assigned to the plurality of closed-side gateway servers associated with one of the call control servers owned by the main closed system and the plurality of closed-side gateway servers associated with one of the call control servers owned by the sub-closed system, and when the closed-side DNS server receives the name resolution request of the closed-side gateway server from the wireless station connected to the closed network, it selects one of the plurality of closed-side gateway servers to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the call control server associated with the plurality of closed-side gateway servers to which the domain name included in the name resolution request is assigned, the operating status of the closed-side gateway server, and the route to the wireless station.

7. The wireless communication system according to claim 6, wherein, when the operating status of the call control server of the main closed system is normal, the closed-side DNS server selects one of the multiple closed-side gateway servers included in the main closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the multiple closed-side gateway servers associated with the call control server of the main closed system and the route to the wireless station, and when the operating status of the call control server of the main closed system is abnormal, the closed-side DNS server selects one of the multiple closed-side gateway servers included in the sub-closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the multiple closed-side gateway servers associated with the call control server of the sub-closed system and the route to the wireless station.

8. The wireless communication system according to claim 6 or 7, wherein the closed system further comprises a plurality of closed-side activation servers that, when receiving an activation request from a wireless station connected to the closed network as the closed-side device, register activation information including specific information that uniquely identifies the wireless station in storage devices provided in the closed system and the cloud system, respectively; the same domain name is assigned to at least one of the plurality of closed-side activation servers owned by the main closed system and at least one of the plurality of closed-side activation servers owned by the sub-closed system; and when the closed-side DNS server receives the name resolution request from the closed-side activation server from the wireless station connected to the closed network, it selects one of the plurality of closed-side activation servers to which the domain name included in the name resolution request is assigned, depending on at least one of the operating statuses of the plurality of closed-side activation servers to which the domain name included in the name resolution request is assigned and the route to the wireless station.

9. The wireless communication system according to claim 8, wherein when the operating status of at least one of the closed-side activation servers owned by the main closed system is normal, the closed-side DNS server selects one of the closed-side activation servers included in the main closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the closed-side activation server owned by the main closed system and the route to the wireless station, and when the operating status of the closed-side activation server owned by the main closed system is abnormal, the closed-side DNS server selects one of the closed-side activation servers included in the sub-closed system and to which the domain name included in the name resolution request is assigned, depending on at least one of the operating status of the closed-side activation server owned by the sub-closed system and the route to the wireless station.

10. A wireless communication system comprising a closed system provided in a closed network and a cloud system provided in an Internet network, said closed system and said cloud system being connected to each other so as to be able to communicate with each other, said closed system comprising a call control server that controls communication between a plurality of wireless stations each connected to either said closed network or said Internet network, a plurality of closed-side gateway servers provided in correspondence with said call control servers and holding the correspondence between said wireless stations and said call control servers, and a closed-side DNS server that performs name resolution of domain names of closed-side devices included in said closed system or cloud-side devices included in said cloud system, said cloud system comprising a cloud-side gateway server that holds the correspondence between said wireless stations and said call control servers, and a management server that acquires the operating status of said closed-side devices, said method of communication performed by said wireless communication system comprising: When receiving a registration request or voice data from the wireless station connected to the closed network, it transmits the registration request or the voice data to the call control server associated with the wireless station, and when receiving a registration response or voice data from the call control server, it transmits the registration response or the voice data to the wireless station that is the destination; by the closed-side DNS server, when receiving a name resolution request for a domain name of a closed-side device included in the closed system or a cloud-side device included in the cloud system from the wireless station connected to the closed network, it performs name resolution of the domain name included in the name resolution request and transmits a name resolution response including an address corresponding to the domain name to the wireless station; by the cloud-side gateway server, when receiving a registration request or voice data from the wireless station connected to the Internet network, it transmits the registration request or the voice data to the call control server associated with the wireless station, and when receiving a registration response or voice data from the call control server addressed to the wireless station connected to the Internet network, it transmits the registration response or the voice data to the wireless station;the closed-side DNS server, upon receiving the name resolution request from the closed-side device, selects one of the closed-side devices from the plurality of closed-side devices corresponding to the domain name, depending on at least one of the acquired operating status of the closed-side device and the route to the wireless station, and transmits the name resolution response including the address of the selected closed-side device to the wireless station.

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