Patent Publication Number: US-2018054722-A1

Title: Communication device, communication terminal, information delivery method, information receiving method, and non-transitory computer readable medium

Description:
TECHNICAL FIELD 
     The present invention relates to a communication device, a communication terminal, an information delivery method, an information receiving method and a program and, particularly, relates to a communication device, a communication terminal, an information delivery method, an information receiving method and a program regarding the delivery of emergency information. 
     BACKGROUND ART 
     In order to deliver emergency information to a communication terminal such as a cellular phone in the event of an earthquake, the specifications for the delivery of emergency information are defined in the 3GPP (3rd Generation Partnership Project). In the 3GPP, the specifications for the delivery of emergency information are defined as a PWS (Public Warning System). Further, in Japan, an ETWS (Earthquake and Tsunami Warning System) is specified for an emergency information delivery system using the PWS. 
     Non Patent Literature 1 defines the specifications of the ETWS and the PWS used in each country. For example, Non Patent Literature 1 specifies the configuration in which a communication terminal that satisfies the specifications of the 3GPP receives emergency information through an eNB (evolved NodeB). 
     CITATION LIST 
     Non Patent Literature 
     NPL1: 3GPP TS22.268 V12.2.0 (2013-06) 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, the communication system disclosed in Non Patent Literature 1 discloses nothing about the delivery of emergency information to a communication terminal that does not satisfy the specifications of the 3GPP. Accordingly, there is a problem that, in the PWS or the ETWS, it is not possible to carry out the delivery of emergency information using wireless LAN (Local Area Network) communications to a communication terminal or the like that is located in a wireless LAN communication area. 
     An exemplary object of the present invention is to provide a communication device, a communication terminal, an information delivery method, an information receiving method and a program that can deliver emergency information to a communication terminal located in a non-3GPP communication area through the non-3GPP communication area. 
     Solution to Problem 
     A communication device according to a first exemplary aspect of the present invention includes an emergency information receiving means for receiving emergency information delivered from a broadcast server located in a 3GPP network, and an emergency information delivery means for delivering the emergency information to a multicast address as a destination and thereby delivering the emergency information to a communication terminal located in a non-3GPP network, the communication terminal having been registered to a multicast group associated with the multicast address. 
     A communication terminal according to a second exemplary aspect of the present invention includes a registration means for making registration to a multicast group managed by a communication device located in the non-3GPP network, and a broadcast communication means for receiving emergency information sent to a multicast address associated with the multicast group from the communication device located in the non-3GPP network and having received the emergency information delivered from a broadcast server located in a 3GPP network. 
     An information delivery method according to a third exemplary aspect of the present invention is an information delivery method in a communication device located in a non-3GPP network, the method including receiving emergency information delivered from a broadcast server located in a 3GPP network, and delivering the emergency information to a multicast address as a destination and thereby delivering the emergency information to a communication terminal located in a non-3GPP network, the communication terminal having been registered to a multicast group associated with the multicast address. 
     An information receiving method according to a fourth exemplary aspect of the present invention is an information receiving method in a communication terminal that performs communications through a non-3GPP network, the method including making registration to a multicast group managed by a communication device located in the non-3GPP network, and receiving emergency information sent to a multicast address associated with the multicast group from the communication device located in the non-3GPP network and having received the emergency information delivered from a broadcast server located in a 3GPP network. 
     A program according to a fifth exemplary aspect of the present invention is a program to be executed by a computer being a communication device located in a non-3GPP network, the program causing the computer to perform receiving emergency information delivered from a broadcast server located in a 3GPP network, and delivering the emergency information to a multicast address as a destination and thereby delivering the emergency information to a communication terminal located in a non-3GPP network, the communication terminal having been registered to a multicast group associated with the multicast address. 
     Advantageous Effects of Invention 
     According to the exemplary aspects of the present invention described above, it is possible to provide a communication device, a communication terminal, an information delivery method, an information receiving method and a program that can deliver emergency information to a communication terminal located in a non-3GPP communication area through the non-3GPP communication area. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a communication system according to a first exemplary embodiment. 
         FIG. 2  is a block diagram of a communication system according to a second exemplary embodiment. 
         FIG. 3  is a block diagram of a UE according to the second exemplary embodiment. 
         FIG. 4  is a block diagram of a TWAN device according to the second exemplary embodiment. 
         FIG. 5  is a view showing the flow of a multicast address notification process according to the second exemplary embodiment. 
         FIG. 6  is a view showing the flow of a multicast address notification process according to the second exemplary embodiment. 
         FIG. 7  is a view showing the flow of a registration process to a multicast group by a UE according to the second exemplary embodiment. 
         FIG. 8  is a view showing the flow of an emergency information delivery process according to the second exemplary embodiment. 
         FIG. 9  is a block diagram of a communication system according to a third exemplary embodiment. 
         FIG. 10  is a block diagram of a PGW according to the third exemplary embodiment. 
         FIG. 11  is a view showing the flow of a registration process to a multicast group by a UE according to the third exemplary embodiment. 
         FIG. 12  is a view showing the flow of an emergency information delivery process according to the third exemplary embodiment. 
         FIG. 13  is a block diagram of a communication system according to a fourth exemplary embodiment. 
         FIG. 14  is a block diagram of an AAA according to the fourth exemplary embodiment. 
         FIG. 15  is a view showing the flow of a registration process to a multicast group by a UE according to the fourth exemplary embodiment. 
         FIG. 16  is a view showing the flow of an emergency information delivery process according to the fourth exemplary embodiment. 
         FIG. 17  is a block diagram of a communication system according to a fifth exemplary embodiment. 
         FIG. 18  is a view showing the flow of a registration process to a multicast group by a UE according to the fifth exemplary embodiment. 
         FIG. 19  is a view showing the flow of an emergency information delivery process according to the fifth exemplary embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Exemplary Embodiment 
     Exemplary embodiments of the present invention are described hereinafter with reference to the drawings. First, a configuration example of a communication system according to a first exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 1 . The communication system in  FIG. 1  includes a communication device  10 , a broadcast server  20  and a communication terminal  30 . The communication device  10  and the communication terminal  30  are located in a non-3GPP network  40 . The broadcast server  20  is located in a 3GPP network  50 . 
     The 3GPP network  50  is a network that is formed by a device which operates in a communication scheme defined in the 3GPP. The non-3GPP network  40  is a network that is formed by a device which operates in a communication scheme not defined in the 3GPP, such as a wireless LAN communication scheme, for example. 
     A configuration example of the communication device  10  is described hereinafter. The communication device  10  may be a computer device that operates by running a program stored in a memory on a processor such as a CPU (Central Processing Unit). The communication device  10  includes an emergency information receiving unit  11  and an emergency information delivery unit  12 . The emergency information receiving unit  11  and the emergency information delivery unit  12  may be software, modules or the like executed by running, on a processor, a program stored in a memory. Alternatively, the emergency information receiving unit  11  and the emergency information delivery unit  12  may be configured using a circuit or the like. 
     The emergency information receiving unit  11  receives emergency information that is delivered from the broadcast server  20  located in the 3GPP network  50 . An interface using a predetermined protocol may be set between the emergency information receiving unit  11  and the broadcast server  20 . The emergency information may be information that notifies about the occurrence of a natural disaster such as an earthquake or a tsunami or information that notifies about the occurrence of a crime or the like, for example. 
     The emergency information delivery unit  12  delivers emergency information to the communication terminal  30  located in the non-3GPP network  40 . To be specific, the emergency information delivery unit  12  delivers emergency information to the communication terminal  30  by setting, as a destination, a multicast address associated with a multicast group to which the communication terminal  30  belongs. 
     The communication terminal  30  is a computer device that operates by running, on a processor, a program stored in a memory, and it may be a cellular phone, a smartphone or the like. 
     As described above, by using the communication system of  FIG. 1 , the communication device  10  located in the non-3GPP network  40  can receive emergency information that is delivered from the broadcast server  20  located in the 3GPP network  50 . Further, the communication terminal  30  previously belongs to a multicast address group that is used for receiving emergency information. Therefore, the communication device  10  can deliver emergency information to the communication terminal  30  by distributing the emergency information to a multicast address to be used for distributing emergency information. As a result, the communication terminal  30  can receive emergency information through the communication device  10  even when it does not belong to the 3GPP network  50 . 
     Second Exemplary Embodiment 
     A configuration example of a communication system according to a second exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 2 . The communication system in  FIG. 2  includes a non-3GPP network  40  and a 3GPP network  50 , just like the communication system in  FIG. 1 . The 3GPP network  50  includes a plurality of UEs (User Equipments)  60 , eNBs (evolved NodeBs)  80 , an MME (Mobility Management Entity)  90 , and a CBC (Cell Broadcast Centre)  100 . Further, the CBC  100  connects to a CBE (Cell Broadcast Entity)  120 . 
     The UE  60  is a general term for communication terminals to be used by users in the 3GPP. The eNB  80  is a base station that performs wireless communications using LTE (Long Term Evolution) specified in the 3GPP. The MME  90  is a device that performs call control for the UE  60 . For example, the MME  90  performs the setting of a communication channel of data between the UE  60  and another UE, the mobility management and control of the UE  60  and the like. 
     The CBC  100  performs the delivery of emergency information generated in the CBE  120  to a delivery area designated by the CBE  120 . For example, when a specific area is designated as a delivery area in the CBE  120 , the CBC  100  identifies the eNB  80  that can deliver emergency information to the area designated by the CBE  120 . Further, the CBC  100  delivers the emergency information to the UE  60  that belongs to the communication area formed by the identified eNB  80 . The CBE  120  may be a server device or the like that is managed by an administrative body which monitors an earthquake, a tsunami or the like, for example. 
     Further, the CBC  100  identifies a TWAN (Trusted Wireless LAN Access Network) device  110  that can deliver emergency information to a designated area, and delivers the emergency information to the UE  70  that belongs to the communication area formed by the identified TWAN device  110 . 
     The non-3GPP network  40  includes UEs  70  and a TWAN (Trusted Wireless LAN Access Network) device  110 . The UE  70  is a UE that has the capability of performing communications through the 3GPP network  50  and performing communications through the TWAN device  110 . In this figure, the case where the UE  70  can perform communications through the non-3GPP network  40  while it cannot perform communications through the 3GPP network  50  due to a reason that it is located outside a 3GPP wireless communication area or the like is described as an example. 
     The TWAN device  110  may be an access point that forms a wireless LAN communication area. The UE  70  that is located in the wireless LAN communication area formed by the TWAN device  110  can receive emergency information delivered from the CBC  100  through the TWAN device  110 . Further, the TWAN device  110  delivers emergency information to the UE  70  by multicast communications. The TWAN device  110  may be a device that is trusted by a telecommunications carrier which manages the 3GPP network  50 ; in other words, a device that is managed by a telecommunications carrier. 
     Further, when the UE  70  is located in a wireless LAN communication area formed in a 3GPP wireless communication area, it may receive emergency information from an access point or the like that forms the wireless LAN communication area. There is a case where UE  70  receives emergency information in both a 3GPP wireless communication area and a wireless LAN communication area, and it may discard either the emergency information received in the former area or that received in the latter area in this case. 
     A configuration example of the UE  70  according to the second exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 3 . The UE  70  includes a 3GPP communication unit  71 , a WLAN (Wireless LAN) communication unit  72 , an emergency information processing control unit  73 , a registration unit  74 , an emergency notification display unit  75  and an emergency notification unit  76 . The 3GPP communication unit  71 , the WLAN communication unit  72 , the emergency information processing control unit  73 , the registration unit  74 , the emergency notification display unit  75  and the emergency notification unit  76  may be software, modules or the like that operate by running a program stored in a memory on a processor of the UE  70 . Alternatively, the 3GPP communication unit  71 , the WLAN communication unit  72 , the emergency information processing control unit  73 , the registration unit  74 , the emergency notification display unit  75  and the emergency notification unit  76  may be configured using a circuit or the like. 
     The 3GPP communication unit  71  communicates with a wireless base station specified in the 3GPP. The wireless base station specified in the 3GPP may be the eNB  80 , for example. The WLAN communication unit  72  communicates with the TWAN device  110  by using wireless LAN communications. The wireless LAN communications may be performed using a communication scheme specified in an IEEE (The Institute of Electrical and Electronics Engineers) 802, for example. 
     The emergency information processing control unit  73  receives emergency information that is delivered from the CBC  100  through the 3GPP communication unit  71  or the WLAN communication unit  72 . For example, when the UE  70  is located in a communication area that is formed by the eNB  80 , it may receive emergency information through the 3GPP communication unit  71 . On the other hand, when the UE  70  is located in a wireless LAN communication area that is formed by the TWAN device  110 , it may receive emergency information through the WLAN communication unit  72 . Further, when the UE  70  is located in an area where a communication area formed by the eNB  80  and a wireless LAN communication area formed by the TWAN device  110  overlap, there is a case where the UE  70  receives the same emergency information from the two wireless systems. In such a case, the emergency information processing control unit  73  may recognize the overlapping reception of emergency information by referring to a message identifier of the delivered emergency information or the like, and discard the emergency information received from either one of the 3GPP communication unit  71  and the WLAN communication unit  72 . 
     The emergency information processing control unit  73  outputs the emergency information received from the 3GPP communication unit  71  or the WLAN communication unit  72  to the emergency notification display unit  75  or the emergency notification unit  76 . 
     The emergency notification display unit  75  displays the emergency information received from the emergency information processing control unit  73  on a display and thereby causes a user of the UE  70  to recognize the emergency information. The emergency notification display unit  75  may make a display format for displaying the emergency information received from the 3GPP communication unit  71  and a display format for displaying the emergency information received from the WLAN communication unit  72  different from or the same as each other. 
     When the emergency notification unit  76  receives the emergency information from the emergency information processing control unit  73 , it outputs a predetermined sound or vibration and thereby causes a user of the UE  70  to recognize the emergency information. The emergency notification unit  76  may make a sound or a vibration to be output when the emergency information is received from the 3GPP communication unit  71  and a sound or a vibration to be output when the emergency information is received from the WLAN communication unit  72  different from or the same as each other. 
     The registration unit  74  performs a registration process to a multicast group that is required when receiving emergency information through the WLAN communication unit  72 . When connecting to the 3GPP network  50  through the 3GPP communication unit  71 , which is, when making Attach to the 3GPP network  50 , the registration unit  74  receives, from the eNB  80 , information about a multicast address that is set as a destination of emergency information. Alternatively, information about a multicast address may be notified to the UE  70  from an AAA (Authentication Authorization Accounting) server located in the 3GPP network  50  by using an EAP (Extensible Authentication Protocol) message at the time of subscriber authentication that is performed when the UE  70  accesses the non-3GPP network  40 . Alternatively, information about a multicast address may be notified to the UE  70  from an ANDSF (Access Network Discovery and Selection Function) server located in an external network of the 3GPP network  50  by using the user plane. Further, the registration unit  74  makes registration to a multicast group associated with the received multicast address in the TWAN device  110  through the WLAN communication unit  72 . For example, the registration unit  74  makes registration to a multicast group that is managed by the TWAN device  110  by executing processing such as IGMP (Internet Group Management Protocol) or MLD (emergency information Multicast Listener Discovery). 
     A configuration example of the TWAN device  110  according to the second exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 4 . The TWAN device  110  includes a wireless LAN communication unit  111 , an emergency information processing unit  112 , a subscriber authentication unit  113  and a gateway communication unit  114 . The wireless LAN communication unit  111 , the emergency information processing unit  112 , the subscriber authentication unit  113  and the gateway communication unit  114  in the TWAN device  110  may be software, modules or the like that operate by running a program stored in a memory on a processor of the TWAN device  110 . Alternatively, the wireless LAN communication unit  111 , the emergency information processing unit  112 , the subscriber authentication unit  113  and the gateway communication unit  114  may be configured using a circuit or the like. 
     The emergency information processing unit  112  receives emergency information that is delivered from the CBC  100 . The emergency information processing unit  112  outputs the received emergency information to the wireless LAN communication unit  111 . The subscriber authentication unit  113  performs an authentication process for the UE  70  that is located in the wireless LAN communication area formed by the TWAN device  110 . For example, the subscriber authentication unit  113  performs an authentication process for the UE  70  with an AAA server, an HSS (Home Subscriber Server) or the like located in the 3GPP network  50 . Further, the subscriber authentication unit  113  manages a multicast group. For example, when a request for registration to a multicast group is notified from the UE  70  that is located in the communication area formed by the TWAN device  110 , the subscriber authentication unit  113  manages the multicast group and the UE  70  in association with each other. 
     The gateway communication unit  114  sends and receives user data, for example, with a gateway device that is located in the 3GPP network  50 . The gateway device that is located in the 3GPP network  50  may be a PGW (Packet data network Gateway), for example. 
     The wireless LAN communication unit  111  performs wireless LAN communications with the UE  70 . Further, when emergency information is output from the emergency information processing unit  112 , the wireless LAN communication unit  111  sends the emergency information to a multicast address as a destination. The emergency information that is sent to a multicast address as a destination is delivered to the UE  70  that is managed in association with the multicast group in the subscriber authentication unit  113 . 
     The flow of a multicast address notification process is described hereinafter with reference to  FIG. 5 . First, the UE  70  turns power to ON in the 3GPP network  50  (S 11 ). Next, the UE  70  sends an Attach request message to the eNB  80  (S 12 ). Then, the eNB  80  sends the Attach request message sent from the UE  70  to the MME  90  (S 13 ). After that, an Attach process for the UE  70  is performed between the UE  70  and the MME  90 . The detailed description of the Attach process is omitted. 
     When an authentication process performed during the Attach process is completed, the MME  90  sends, to the eNB  80 , an Initial Context Setup Request/ATTACH accept message to which a multicast address is set (S 14 ). The multicast address that is set to the Initial Context Setup Request/ATTACH accept message is an address that is required when the UE  70  receives emergency information in the case where it is located in the wireless LAN communication area formed by the TWAN device  110 . 
     When the eNB  80  receives the Initial Context Setup Request/ATTACH accept message, it sends an RRC Connection Reconfiguration/ATTACH accept message to the UE  70  (S 15 ). The eNB  80  sets the multicast address that is set to the Initial Context Setup Request/ATTACH accept message to the RRC Connection Reconfiguration/ATTACH accept message. Information about the multicast address may be notified from the MME  90  to the UE  70  by using a PCO (Protocol Configuration Option) parameter that is set to the ATTACH accept message. 
     As described above, in the Attach process to the 3GPP network  50 , the UE  70  can receive a multicast address required for receiving emergency information in the wireless LAN communication area formed by the TWAN device  110 . 
     The flow of a multicast address notification process which is different from that in  FIG. 5  is described hereinafter with reference to  FIG. 6 . While the flow of the process when the UE  70  receives a multicast address through the eNB  80  located in the 3GPP network  50  is described in  FIG. 5 , the flow of the process when the UE  70  receives a multicast address through the TWAN device  110  is described in  FIG. 6 . 
       FIG. 6  is based on the premise that an authentication process for the UE  70  that is located in the communication area formed by the TWAN device  110  has been performed in the AAA server and the HSS located in the 3GPP network  50 . Specifically, the AAA server and the HSS perform authentication as to whether the UE  70  can use the 3GPP network  50  through the TWAN device  110  or not. It is assumed in this example that the AAA server and the HSS have determined to authorize the UE  70  to use the 3GPP network  50  through the TWAN device  110 . 
     In this case, the AAA server sends an AAA(EAP(PPP Extensible Authentication Protocol)-Success) message to the TWAN device  110  (S 21 ). Further, the AAA server sets a multicast address to the AAA(EAP-Success) message. 
     Then, the TWAN device  110  sends an EAP-Success message to the UE  70  (S 22 ). The TWAN device  110  sets the multicast address that is set to the AAA(EAP-Success) message to the EAP-Success message. The UE  70  receives the EAP-Success message and can thereby receive the multicast address that is required for receiving emergency information in the wireless LAN communication area formed by the TWAN device  110 . Information about the multicast address may be notified from the TWAN device  110  to the UE  70  by using a PCO parameter that is set to the EAP-Success message. 
     The flow of a registration process to a multicast group by the UE  70  according to the second exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 7 .  FIG. 7  is based on the premise that the setting of a session between the TWAN device  110  and the PGW located in the 3GPP network  50  has been completed, and further the UE  70  has acquired a multicast address. For example, the setting of a session between the TWAN device  110  and the PGW may be the setting of a GTP (General Packet Radio Service Tunneling Protocol) Tunnel to be used when transmitting and receiving data between the TWAN device  110  and the PGW. 
     When the setting of a session between the TWAN device  110  and the PGW is completed, the UE  70  makes registration to a multicast group associated with a multicast address held by itself in the TWAN device  110  (S 31 ). For example, the UE  70  makes registration to a multicast group that is managed by the TWAN device  110  by an IGMP or MLD procedure. 
     The flow of an emergency information delivery process according to the second exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 8 . In  FIG. 8 , it is assumed that the UE  70  has completed the registration to a multicast group that is managed by the TWAN device  110 . 
     First, the CBE  120  sends, to the CBC  100 , an Emergency Broadcast Request message that instructs the delivery of emergency information (S 41 ). Next, the CBC  100  sends, to the TWAN device  110 , a Write-Replace Warning Request message that instructs the delivery of emergency information (S 42 ). The CBC  100  sends the Write-Replace Warning Request message to the TWAN device  110  by using a predetermined protocol with the TWAN device  110 . In other words, the CBC  100  sends the Write-Replace Warning Request message to the TWAN device  110  by using a predetermined interface with the TWAN device  110 . The interface between the CBC  100  and the TWAN device  110  may be the interface specified in the 3GPP, for example. 
     The TWAN device  110  compares area information (Warning Area Information) for broadcasting the emergency information contained in the Write-Replace Warning Request message with the geographical location of the communication area formed by itself. When the communication area formed by the TWAN device  110  itself is included in the area indicated by the Warning Area Information, the TWAN device  110  broadcasts the emergency information to the multicast address as a destination (S 43 ). The communication area formed by itself may be determined for each wireless LAN communication unit  111 . 
     As a result that the TWAN device  110  broadcasts emergency information to the multicast address as a destination, the emergency information is delivered to the UE  70  that belongs to the multicast group associated with the multicast address 
     Next, the TWAN device  110  sends a Write-Replace Warning Confirm message to the CBC  100  as a response message to the Write-Replace Warning Request message (S 44 ). The CBC  100  then sends an Emergency Broadcast Response message to the CBE  120  as a response message to the Emergency Broadcast Request message (S 45 ). 
     As described above, by using the communication system according to the second exemplary embodiment of the present invention, the CBC  100  can send emergency information to the TWAN device  110  through a predetermined interface. Further, the UE  70  can acquire a multicast address for the delivery of emergency information in advance, and make registration to a multicast group associated with the multicast address for the delivery of emergency information. Therefore, the TWAN device  110  sends the emergency information sent from the CBC  100  to the multicast address as a destination and can thereby deliver the emergency information to the UE  70 . 
     The UE  70  can thereby receive the emergency information delivered from the CBC  100  through the TWAN device  110 , in addition to receiving the emergency information through the 3GPP network  50 . 
     Third Exemplary Embodiment 
     A configuration example of a communication system according to a third exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 9 . The communication system in  FIG. 9  has the configuration where a PGW (Packet Data Network Gateway) is placed between the TWAN device  110  and the CBC  100 . The other configuration of the communication system in  FIG. 9  is the same as that in  FIG. 2 , and therefore the detailed description thereof is omitted. 
     A PGW  130  is located in the 3GPP network  50 . The CBC  100  sends emergency information to the PGW  130  by using a predetermined protocol with the PGW  130 . Further, the PGW  130  sends the emergency information sent from the CBC  100  to the TWAN device  110  by using a predetermined protocol. The PGW  130  may send the emergency information sent from the CBC  100  to the TWAN device  110  by using a GTP protocol, user plane data using a GTP protocol, or a PMIP (Proxy Mobile IP) protocol. 
     A configuration example of the PGW  130  according to the third exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 10 . The PGW  130  includes an emergency report processing unit  131 , a control signal processing unit  132  and a user plane processing unit  133 . The emergency report processing unit  131 , the control signal processing unit  132  and the user plane processing unit  133  may be software, modules or the like executed by running a program stored in a memory on a processor of the PGW  130 . Alternatively, the emergency report processing unit  131 , the control signal processing unit  132  and the user plane processing unit  133  may be configured using a circuit or the like. 
     The user plane processing unit  133  sends and receives user data to and from an external network such as the Internet. Further, the user plane processing unit  133  sends and receives user data also to and from the TWAN device  110 . 
     The emergency report processing unit  131  receives emergency information sent from the CBC  100 . The control signal processing unit  132  sends the emergency information sent from the CBC  100  as control information to the TWAN device  110 . 
     The flow of a registration process to a multicast group by the UE  70  according to the third exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 11 .  FIG. 11  is based on the premise that the setting of a session between the TWAN device  110  and the PGW  130  located in the 3GPP network  50  has been completed, and further the UE  70  has acquired a multicast address. For example, the setting of a session between the TWAN device  110  and the PGW may be the setting of a GTP Tunnel to be used when transmitting and receiving data between the TWAN device  110  and the PGW  130 . 
     Step S 51  is the same as Step S 31  in  FIG. 7  and therefore not redundantly described in detail. When the TWAN device  110  completes the registration of the UE  70  to a multicast group, it sends, to the PGW  130 , a multicast group registration notification message which notifies that the UE  70  is registered to a multicast group for delivering emergency information (S 52 ). The multicast group registration notification message may be a GTP message, a PMIP message or the like, for example. 
     Then, the PGW  130  sends an Acknowledge message to the TWAN device  110  as a response to the multicast group registration notification message (S 53 ). 
     The flow of an emergency information delivery process according to the third exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 12 . In  FIG. 12 , it is assumed that the UE  70  has completed the registration to a multicast group that is managed by the TWAN device  110 . 
     First, the CBE  120  sends, to the CBC  100 , an Emergency Broadcast Request message that instructs the delivery of emergency information (S 61 ). Next, the CBC  100  sends, to the PGW  130 , a Write-Replace Warning Request message that instructs the delivery of emergency information (S 62 ). The CBC  100  sends the Write-Replace Warning Request message to the PGW  130  by using a predetermined protocol with the PGW  130 . In other words, the CBC  100  sends the Write-Replace Warning Request message to the PGW  130  by using a predetermined interface with the PGW  130 . The interface between the CBC  100  and the PGW  130  may be the interface specified in the 3GPP, for example. 
     Then, the PGW  130  sends a Write-Replace Warning Request message to the TWAN device  110  by using a predetermined protocol with the TWAN device  110 . In other words, the PGW  130  sends the Write-Replace Warning Request to the TWAN device  110  by using a predetermined interface with the TWAN device  110 . The interface between the PGW  130  and the TWAN device  110  may be the interface specified in the 3GPP, for example. 
     The TWAN device  110  compares area information (Warning Area Information) for broadcasting the emergency information contained in the Write-Replace Warning Request message with the geographical location of the communication area formed by itself. When the communication area formed by the TWAN device  110  itself is included in the area indicated by the Warning Area Information, the TWAN device  110  broadcasts the emergency information to the multicast address as a destination (S 64 ). 
     As a result that the TWAN device  110  broadcasts the emergency information to the multicast address as a destination, the emergency information is delivered to the UE  70  that belongs to the multicast group associated with the multicast address. 
     Next, the TWAN device  110  sends a Write-Replace Warning Confirm message to the PGW  130  as a response message to the Write-Replace Warning Request message (S 65 ). The PGW  130  then sends a Write-Replace Warning Confirm message to the CBC  100  as a response message to the Write-Replace Warning Request message (S 66 ). 
     Then, the CBC  100  sends an Emergency Broadcast Response message to the CBE  120  as a response message to the Emergency Broadcast Request message (S 67 ). 
     As described above, by using the communication system according to the third exemplary embodiment of the present invention, the CBC  100  can send emergency information to the TWAN device  110  via the PGW  130  through a predetermined interface. Further, the UE  70  can acquire a multicast address for the delivery of emergency information in advance, and make registration to a multicast group associated with the multicast address for the delivery of emergency information. Therefore, the TWAN device  110  sends emergency information sent from the CBC  100  to the multicast address as a destination and can thereby deliver the emergency information to the UE  70 . 
     The UE  70  can thereby receive the emergency information delivered from the CBC  100  through the TWAN device  110 , in addition to receiving the emergency information through the 3GPP network  50 . 
     Fourth Exemplary Embodiment 
     A configuration example of a communication system according to a fourth exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 13 . The communication system in  FIG. 13  has the configuration where an AAA server  140  is placed instead of the PGW  130  in the communication system of  FIG. 9 . The other configuration of the communication system in  FIG. 13  is the same as that in  FIG. 9 , and therefore the detailed description thereof is omitted. 
     The AAA server  140  is located in the 3GPP network  50 . The CBC  100  sends emergency information to the AAA server  140  by using a predetermined protocol with the AAA server  140 . Further, the AAA server  140  sends the emergency information sent from the CBC  100  to the TWAN device  110  by using a predetermined protocol. 
     A configuration example of the AAA server  140  according to the third exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 14 . The AAA server  140  includes an emergency report processing unit  141  and a subscriber authentication unit  142 . The emergency report processing unit  141  and the subscriber authentication unit  142  may be software, modules or the like executed by running a program stored in a memory on a processor of the AAA server  140 . Alternatively, the emergency report processing unit  141  and the subscriber authentication unit  142  may be configured using a circuit or the like. 
     The emergency report processing unit  141  receives emergency information sent from the CBC  100 . The emergency report processing unit  141  sends the emergency information sent from the CBC  100  as control information to the TWAN device  110 . The subscriber authentication unit  142  performs an authentication process for the UE  60 , the UE  70  and the like in corporation with the HSS. 
     The flow of a registration process to a multicast group by the UE  70  according to the fourth exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 15 .  FIG. 15  is based on the premise that the setting of a session between the TWAN device  110  and the PGW located in the 3GPP network  50  has been completed, and further the UE  70  has acquired a multicast address. For example, the setting of a session between the TWAN device  110  and the PGW may be the setting of a GTP Tunnel to be used when transmitting and receiving data between the TWAN device  110  and the PGW. 
     Step S 71  is the same as Step S 31  in  FIG. 7  and therefore not redundantly described in detail. When the TWAN device  110  completes the registration of the UE  70  to a multicast group, it sends, to the AAA server  140 , a multicast group registration notification message which notifies that the UE  70  is registered to a multicast group for delivering emergency information (S 72 ). The multicast group registration notification message may be a DIAMETER message, a Radius message or the like, for example. 
     Then, the AAA server  140  sends an Acknowledge message to the TWAN device  110  as a response to the multicast group registration notification message (S 73 ). 
     The flow of an emergency information delivery process according to the fourth exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 16 . The process in  FIG. 16  is the same as the process in  FIG. 12  except that the PGW  130  in  FIG. 12  is replaced with the AAA server  140 . Therefore, the detailed description of  FIG. 16  is omitted. 
     As described above, by using the communication system according to the third exemplary embodiment of the present invention, the CBC  100  can send emergency information to the TWAN device  110  via the AAA server  140  through a predetermined interface. Further, the UE  70  can acquire a multicast address for the delivery of emergency information in advance, and make registration to a multicast group associated with the multicast address for the delivery of emergency information. Therefore, the TWAN device  110  sends emergency information sent from the CBC  100  to the multicast address as a destination and can thereby deliver the emergency information to the UE  70 . 
     The UE  70  can thereby receive the emergency information delivered from the CBC  100  through the TWAN device  110 , in addition to receiving the emergency information through the 3GPP network  50 . 
     Fifth Exemplary Embodiment 
     A configuration example of a communication system according to a fifth exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 17 . In the communication system in  FIG. 17 , the AAA server  140  is removed from the communication system in  FIG. 13 , and the MME  90  and the TWAN device  110  are connected. 
     The MME  90  sends emergency information sent from the CBC  100  to the TWAN device  110  by using a predetermined protocol. 
     The flow of a registration process to a multicast group by the UE  70  according to the fifth exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 18 .  FIG. 18  is based on the premise that the setting of a session between the TWAN device  110  and the PGW located in the 3GPP network  50  has been completed, and further the UE  70  has acquired a multicast address. For example, the setting of a session between the TWAN device  110  and the PGW may be the setting of a GTP Tunnel to be used when transmitting and receiving data between the TWAN device  110  and the PGW. 
     Step S 91  is the same as Step S 31  in  FIG. 7  and therefore not redundantly described in detail. When the TWAN device  110  completes the registration of the UE  70  to a multicast group, it sends, to the MME  90 , a multicast group registration notification message which notifies that the UE  70  is registered to a multicast group for delivering emergency information (S 92 ). The multicast group registration notification message may be a message using a protocol specified in the 3GPP, for example. 
     Then, the MME  90  sends an Acknowledge message to the TWAN device  110  as a response to the multicast group registration notification message (S 93 ). 
     The flow of an emergency information delivery process according to the fifth exemplary embodiment of the present invention is described hereinafter with reference to  FIG. 19 . The process in  FIG. 19  is the same as the process in  FIG. 12  except that the PGW  130  in  FIG. 12  is replaced with the MME  90 . Therefore, the detailed description of  FIG. 19  is omitted. 
     As described above, by using the communication system according to the fifth exemplary embodiment of the present invention, the CBC  100  can send emergency information to the TWAN device  110  via the MME  90  through a predetermined interface. Further, the UE  70  can acquire a multicast address for the delivery of emergency information in advance, and make registration to a multicast group associated with the multicast address for the delivery of emergency information. Therefore, the TWAN device  110  sends emergency information sent from the CBC  100  to the multicast address as a destination and can thereby deliver the emergency information to the UE  70 . 
     The UE  70  can thereby receive the emergency information delivered from the CBC  100  through the TWAN device  110 , in addition to the case where it is located in the 3GPP network  50 . 
     Although the present invention is described as a hardware configuration in the above exemplary embodiments, the present invention is not limited thereto. The present invention may be implemented by causing a CPU (Central Processing Unit) to execute a computer program to perform processing in the communication terminal (e.g., UE  70  etc.), the communication device (e.g., TWAN device  110  etc.) and each of the node devices located in the 3GPP network. 
     In the above example, the program can be stored and provided to the computer using any type of non-transitory computer readable medium. The non-transitory computer readable medium includes any type of tangible storage medium. Examples of the non-transitory computer readable medium include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), optical magnetic storage media (e.g. magneto-optical disks), CD-ROM (Read Only Memory), CD-R , CD-R/W, DVD-ROM (Digital Versatile Disc Read Only Memory), DVD-R (DVD Recordable)), DVD-R DL (DVD-R Dual Layer)), DVD-RW (DVD ReWritable)), DVD-RAM), DVD+R), DVR+R DL), DVD+RW), BD-R (Blu-ray (registered trademark) Disc Recordable)), BD-RE (Blu-ray (registered trademark) Disc Rewritable)), BD-ROM), and semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory), etc.). The program may be provided to a computer using any type of transitory computer readable medium. Examples of the transitory computer readable medium include electric signals, optical signals, and electromagnetic waves. The transitory computer readable medium can provide the program to a computer via a wired communication line such as an electric wire or optical fiber or a wireless communication line. 
     It should be noted that the present invention is not limited to the above-described exemplary embodiments and may be varied in many ways within the scope of the present invention. 
     While the invention has been particularly shown and described with reference to exemplary embodiments thereof, the invention is not limited to these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims. 
     This application is based upon and claims the benefit of priority from Japanese patent application No. 2015-053051 filed on Mar. 17, 2015, the disclosure of which is incorporated herein in its entirety by reference. 
     REFERENCE SIGNS LIST 
     
         
           10  COMMUNICATION DEVICE 
           11  EMERGENCY INFORMATION RECEIVING UNIT 
           12  EMERGENCY INFORMATION DELIVERY UNIT 
           20  BROADCAST SERVER 
           30  COMMUNICATION TERMINAL 
           40  NON-3GPP NETWORK 
           50  3GPP NETWORK 
           60  UE 
           70  UE 
           71  3GPP COMMUNICATION UNIT 
           72  WLAN COMMUNICATION UNIT 
           73  EMERGENCY INFORMATION PROCESSING CONTROL UNIT 
           74  REGISTRATION UNIT 
           75  EMERGENCY NOTIFICATION DISPLAY UNIT 
           76  EMERGENCY NOTIFICATION UNIT 
           80  eNB 
           90  MME 
           100  CBC 
           110  TWAN DEVICE 
           111  WIRELESS LAN COMMUNICATION UNIT 
           112  EMERGENCY INFORMATION PROCESSING UNIT 
           113  SUBSCRIBER AUTHENTICATION UNIT 
           114  GATEWAY COMMUNICATION UNIT 
           120  CBE 
           130  PGW 
           131  EMERGENCY REPORT PROCESSING UNIT 
           132  CONTROL SIGNAL PROCESSING UNIT 
           133  USER PLANE PROCESSING UNIT 
           140  AAA SERVER 
           141  EMERGENCY REPORT PROCESSING UNIT 
           142  SUBSCRIBER AUTHENTICATION UNIT