JP2016208467A - Communication control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication control system which can change a connection destination of a communication terminal between two communication networks while keeping an audio communication and introduce a plurality of relay nodes for relaying a signal of the communication terminal.SOLUTION: E-CSCF 30s are provided as a plurality of relay nodes, and then the E-CSCF 30 creates identification information, and transmits it to an MME 50 as a terminal management device. When a UE 90 being the communication terminal changes a connection destination, the UE 90 transfers the identification information from the MME 50 to an MSC 70 as a line exchange device. Thereby, the MSC 70 can specify the E-CSCF 30 which relays a signal related to the UE 90. Therefore, an appropriate device is selected out of a plurality of E-CSCF 30s and can perform line exchanges.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a communication control system.

  Voice over LTE (VoLTE), which replaces voice communication that has been performed in the conventional circuit switching system with packet communication as voice communication over LTE (Long Term Evolution) network standardized by 3GPP (3rd Generation Partnership Project) Is adopted. In VoLTE, voice communication is performed using an IMS (IP multimedia subsystem) network, which is a system for controlling IP (Internet Protocol) -based multimedia services.

  In 3GPP, Non-Patent Document 1 defines an emergency call using an IMS network. Non-Patent Document 1 shows that an E-CSCF is used as a node that relays a SIP signal between a terminal used by a user and an SIP server of an IMS network in an IMS emergency call.

3GPP TS 23.167 IP Multimedia Subsystem (IMS) emergency sessions

  By the way, Non-Patent Document 1 does not show a procedure assuming that a plurality of emergency call relay nodes such as E-CSCF are arranged on a network. For this reason, it is difficult to introduce a plurality of emergency call relay nodes in consideration of failure. Specifically, when the communication terminal changes the connection destination between the two communication networks while continuing the voice communication, the circuit switching device that performs the circuit switching process sets the relay node that relays the signal of the communication terminal. There was a problem that multiple relay nodes could not be selected.

  The present invention has been made in view of the above, and is a communication control system capable of changing the connection destination of a communication terminal between two communication networks while continuing voice communication. An object is to provide a communication control system capable of introducing a plurality of relay nodes to be relayed.

  In order to achieve the above object, a communication control system according to the present invention enables a communication terminal connectable to the first communication network and the second communication network to perform voice communication with an application server that provides a voice communication service. A communication control system for controlling communication of the communication terminal when changing the connection destination from the first communication network to the second communication network in a continuous state, and capable of relaying signals related to voice communication by the communication terminal A plurality of relay nodes, a communication control device that controls communication of the communication terminal using the first communication network, a terminal management device that manages a connection status of the communication terminal in the first communication network, A circuit switching device that controls circuit switching from the first communication network to the second communication network, and the relay node generates identification information generating means for generating identification information for identifying the device; identification The identification information generated by the information generation means is associated with information for identifying the communication terminal for which the device is relaying the signal and transmitted to the terminal management device via the communication control device And storing the identification information of the relay node that relays the signal related to voice communication of the communication terminal in association with the information specifying the communication terminal. And identification information transfer means for transmitting the identification information stored in the storage means to the circuit switching device, wherein the circuit switching device includes the identification information transmitted from the terminal management device. And a relay node setting unit that selects a relay node that relays voice communication of the communication terminal from the plurality of relay nodes and performs circuit switching related to the communication terminal. To.

  As described above, by providing a plurality of relay nodes, each relay node generates identification information and transmits the identification information to the terminal management apparatus, thereby relaying the signal related to the communication terminal The terminal management apparatus can grasp the node. At this time, the configuration is such that the identification information of the relay node is transferred via the communication control device, so that the identification information can be transferred via the device of the own system regardless of the contract destination of the communication terminal. . In addition, since the identification information is transferred to the circuit switching device, the circuit switching device can also identify the relay node that relays the signal related to the communication terminal. Circuit switching can be performed by selecting an appropriate relay node. Therefore, according to the communication control system, a plurality of relay nodes can be installed.

  The plurality of relay nodes may be emergency call relay nodes that relay emergency call communication by the communication terminal.

  With this configuration, even when a plurality of emergency call relay nodes are arranged, the circuit switching device can select the emergency call relay node related to the communication terminal and perform circuit switching. It becomes. Accordingly, a plurality of emergency call relay nodes can be introduced in the communication control system, and emergency call connection can be performed more suitably.

  In addition, the relay node includes a determination unit that specifies a transmission path for transmitting the identification information generated by the identification information generation unit to the terminal management device, and the identification information transmission unit is configured by the determination unit. Based on the designation, the transmission path for transmission to the terminal management apparatus can be changed.

  Thus, when it is set as the structure which changes the transmission path | route of identification information based on the designation | designated by a determination means, for example, the determination means can determine the path | route which can transmit identification information with respect to a terminal management apparatus with less communication amount Therefore, it is possible to suppress an increase in load as a system.

  Moreover, the said determination means can be set as the aspect which designates the transmission path | route which passes along the said communication control apparatus, when the said communication terminal is a roaming in terminal.

  When the communication terminal is a roaming-in terminal, an external device may be used as a device different from the communication control device. Therefore, by specifying a transmission path that passes through the communication control device and transmitting the identification information, even if the communication terminal is a roaming-in terminal, the identification information is reliably notified to the terminal management device and the circuit switching device. can do.

  The determination unit uses a transmission path that passes through the communication control apparatus when the transmission path that does not pass through the communication control apparatus is a first path and the identification information cannot be transmitted through the first path. It can be set as the aspect which designates this.

  With the above configuration, for example, the route through which the identification information can be transmitted to the terminal management apparatus with a smaller communication amount is specified as the first route, while the identification information is transmitted through the first route. If it is not possible, the identification information can be transmitted via the communication control device. Therefore, the identification information of the relay server can be transmitted using a more suitable route according to the operation status of each device of the communication terminal or system.

  The first communication network may be an LTE network, and the second communication network may be a 3G network.

  The communication control system according to the present invention is suitably used when the first communication network is an LTE network and the second communication network is a 3G network.

  According to the present invention, there is provided a communication control system capable of changing a connection destination of a communication terminal between two communication networks while continuing voice communication, and includes a plurality of relay nodes that relay a signal of the communication terminal. A communication control system that can be installed is provided.

It is a figure explaining the schematic structure of the communication control system concerning a 1st embodiment. It is a figure which shows the hardware constitutions which concern on each apparatus of a communication control system. It is a figure which shows the functional block of E-CSCF, MME, and MSC which comprise a communication control system. It is a figure which shows the example of the information hold | maintained by profile DB of MME. It is a figure explaining the path | route of the signal in a communication control system. It is a figure explaining the notification method of E-STN-SR by a communication control system. It is a figure explaining the process which concerns on SRVCC of UE by a communication control system. It is a figure explaining the communication control system which concerns on 2nd Embodiment. It is a figure explaining the notification method of E-STN-SR by a communication control system. It is a figure explaining the error determination in E-CSCF of a communication control system.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a diagram showing an overall configuration of a communication control system according to the first embodiment of the present invention. The communication control system 1 shown in FIG. 1 conforms to a communication standard (communication protocol) of an LTE (Long Term Evolution) network N1 (first communication network) and a 3G (3rd Generation) network N2 (second communication network). The communication system provides data communication such as VoLTE (Voice over LTE) to the terminal device. As shown in FIG. 1, the communication control system 1 includes an AS (Application Server) 10, an S-CSCF (Serving Call Session Control Function) 20, and an E-CSCF (Emergency Call Session Control Function) 30 (30A, 30B, 30C), Policy and Charging Rules Function (PCRF) 40, Packet Data Network Gateway (P-GW) 42, Serving Gateway (S-GW) 44, e-Node B (eNB) 46, Mobility (MME) Management Entity) 50, HSS (Home Subscriber Server) 60, MSC (Mobile Switching Center) 70, and RNC (Radio Network Controller) 80. The communication control system 1 is capable of communicating with a UE (User Equipment) 90 that is a mobile communication terminal carried by a user. UE90 (communication terminal) is implement | achieved as a tablet terminal, a smart phone, etc., for example.

  The UE 90 is connected to an IMS (IP Multimedia Subsystem) core network including the HSS 60, the S-CSCF 20 and the E-CSCF 30 in the configuration of the communication control system 1, and provides various services by wireless communication. Can receive. Examples of the various services include a voice communication (VoLTE: Voice over LTE) service and a data communication service (for example, data communication such as SMS or e-mail) in the LTE network N1. Further, the UE 90 can also receive provision of voice communication based on the circuit switching method and data communication service based on the packet switching method by wireless communication via the 3G network N2 by performing communication with the RNC 80 of the communication control system 1.

  This embodiment demonstrates the case where UE90 is a roaming in terminal. The roaming-in terminal is a communication terminal that has a contract with a communication carrier (for example, an overseas communication carrier) different from the communication carrier that provides the communication control system 1, and is provided by the communication control system 1. This is a terminal capable of performing communication using the LTE network N1 and the 3G network N2. As described above, when the UE 90 is a roaming-in terminal, basically, voice communication or the like can be performed using each device configuring the communication control system 1, but for example, processing related to authentication or the like is included. In addition, it is necessary to perform various processes with a device that holds information related to the contract of the UE 90 and the like. Therefore, communication is performed with an apparatus prepared by a contracted communication carrier (in this embodiment, an overseas communication carrier). In the case of the present embodiment, as shown in FIG. 1, when the UE 90 performs voice communication, the UE 90 also performs communication with the AS 10X, the S-CSCF 20X, and the HSS 60X provided by the communication carrier with which the UE 90 is contracted. Details will be described later.

  Further, in the present embodiment, a case will be described in which the communication network connected from the LTE network N1 to the 3G network N2 is changed after the UE 90 starts an emergency call while being in the LTE network N1. The emergency call refers to voice communication for contacting an emergency response organization in the event of an emergency such as a criminal case or a disaster, and is transmitted when a user dials an emergency call telephone number. In addition, a method of changing the communication network connected from the LTE network N1 to the 3G network N2 while continuing the voice communication is defined by the 3GPP standard as SRVCC (Single Radio Voice Call Continuity) (3GPP TS 23.216: Single Radio Voice Call Continuity (SRVCC)).

  FIG. 2 is a diagram illustrating a hardware configuration of each device included in the communication control system 1 of the present embodiment. That is, AS10, S-CSCF20, E-CSCF30, PCRF40, P-GW42, S-GW44, eNB46, MME50, HSS60, MSC70, and RNC75 shown in FIG. 1 are physically as shown in FIG. CPU 101, RAM 102 and ROM 103 as main storage devices, communication module 104 as data transmission / reception device, auxiliary storage device 105 exemplified by hard disk, flash memory, etc., input device exemplified by touch panel and keyboard as input devices 106, and a computer system including an output device 107 such as a display. In AS10, S-CSCF20, E-CSCF30, PCRF40, P-GW42, S-GW44, eNB46, MME50, HSS60, MSC70, and RNC75, predetermined computer software is installed on hardware such as CPU101 and RAM102 shown in FIG. By reading the data, the communication module 104, the input device 106, and the output device 107 are operated under the control of the CPU 101, and reading and writing of data in the RAM 102 and the auxiliary storage device 105 are performed. Function is realized.

  Hereinafter, returning to FIG. 1, the function of each device will be described in detail.

  The AS 10 is an application server that provides various services including a voice communication service. The UE 90 can perform voice communication by connecting to the AS 10.

  The S-CSCF 20 is a logical node that is connected to the UE 90 and performs call session control in IMS. The S-CSCF 20 is a logical node that processes SIP messages as a SIP (Session Initiation Protocol) server, and controls user registration and session settings.

  The E-CSCF 30 has a function of relaying a SIP signal between the UE 90 and the S-CSCF 20 (or S-CSCF 20X) for an emergency call from the UE 90 located in the LTE network N1. That is, the E-CSCF 30 is a relay node that relays a signal related to voice communication, and in particular, is an emergency call relay node corresponding to an emergency call by the UE 90. The present embodiment is characterized in that E-CSCFs 30A to 30C are provided as a plurality of relay nodes, but details will be described later.

  The PCRF 40 is an exchange that determines a QoS value and a charging system to be applied to a user data packet transmitted / received to / from the UE 90 via the LTE network N1.

  The P-GW 42 is a connection point with a PDN (Packet Data Network) that is an external network, and has a function of assigning an IP address, transferring a packet to the S-GW 44, and the like.

  The S-GW 44 has a function as a visited packet gateway that accommodates the 3GPP access system.

  In the present embodiment, the PCRF 40, the P-GW 42, and the S-GW 44 are communication control apparatuses that perform communication control when the UE 90 performs communication via the LTE network N1.

  The eNB 46 has a function as a base station.

  The MME 50 is a logical node that accommodates the eNB 46 and has a function of providing mobility control and the like. The MME 50 has a function of holding a profile related to a communication terminal that performs communication using the eNB 46. That is, the MME 50 is a terminal management device that holds the connection status and the like of communication terminals that communicate via the LTE network N1 like the UE 90.

  The HSS 60 is a subscriber information management server (subscriber information management database) that manages contract information, authentication information, and location information of communication terminals such as the UE 90.

  The MSC 70 is a logical node having a circuit switched function defined on 3GPP. That is, the MSC 70 is a circuit switching device that performs processing related to circuit switching of a communication terminal that changes a connection destination from the LTE network N1 to the 3G network N2.

  The RNC 75 is a radio network control device that is provided above the base station device in the 3G network N2.

  The communication control system 1 according to this embodiment includes a plurality of E-CSCFs 30 that relay SIP signals related to emergency calls. The configuration including a plurality of E-CSCFs 30 is not assumed in the 3GPP standard. In the 3GPP standard, there is no provision for processing regarding the E-CSCF 30, that is, for an emergency call, assuming that there are a plurality of devices in the IMS network (3GPP TS 23.167 IP Multimedia Subsystem (IMS) emergency sessions). . That is, in the 3GPP standard, it is not assumed that a plurality of E-CSCFs 30 are provided in the IMS network.

  However, if there is no alternative means when a failure occurs in the E-CSCF 30, communication related to an emergency call cannot be performed. The same applies to a case where traffic (communication amount) related to an emergency call increases and cannot be processed by one E-CSCF 30. Therefore, the communication control system 1 according to the present embodiment has a configuration in which an emergency call can be reliably processed as compared with the conventional configuration by including a plurality of E-CSCFs 30.

  However, when the communication control system 1 is configured to include a plurality of E-CSCFs 30 as shown in FIG. That is, assume that the UE 90 changes the connection destination from the LTE network N1 to the 3G network N2 while continuing the communication related to the emergency call by SRVCC. In this case, when the voice communication is continued in the 3G network N2, it is necessary to perform communication between the MSC 70 and the E-CSCF 30 in order for the MSC 70 to perform processing related to circuit switching. However, since the conventional 3GPP standard does not assume that there are a plurality of E-CSCFs 30 related to emergency calls, it is impossible to connect to the E-CSCF 30.

  This point will be further described with reference to FIG. At the stage where the UE 90 is located in the LTE network N1 and starts an emergency call, the UE 90 is connected in order from the UE 90 side as shown by the broken line L1 in FIG. , ENB26, S-GW44, P-GW42, E-CSCF30A, and S-CSCF20X, it is assumed that a communication path is provided and communication is performed with AS10X.

  Here, when the UE 90 moves from the LTE network N1 to the 3G network N2 side, the SRVCC request is transmitted to the MME 50 by the eNB 46 to which the UE 90 has been connected. Next, an SRVCC request is transmitted from the MME 50 to the MSC 70 on the 3G network N2 side. Thereafter, a radio switching request is transmitted from the MSC 70 to the RNC 80. Thereafter, a radio switch completion notification is transmitted from the MSC 70 to the E-CSCF 30A. Thereafter, when a wireless switching notification is transmitted from the E-CSCF 30A to the S-CSCF 20X, the communication path is switched in cooperation between the S-CSCF 20X and the AS 10X. These processes are performed by communication between the devices indicated by the solid line L2 in FIG.

  As a result, as indicated by the broken line L3 in FIG. 1, communication can be performed with the AS 10X via the RNC 80, the MSC 70, the E-CSCF 30A, and the S-CSCF 20X in order from the UE 90 side. .

  However, in the conventional 3GPP standard, it is not assumed that there are a plurality of E-CSCFs 30. Therefore, when the MSC 70 attempts to transmit a radio switching completion notification based on the procedure defined in 3GPP, the transmission target There is no procedure for selecting the E-CSCF to be selected from a plurality of E-CSCFs 30. Therefore, as shown in FIG. 1, transmission and reception of signals between the MSC 70 and the E-CSCF 30A cannot be performed.

  Therefore, the communication control system 1 according to the present embodiment includes a configuration in which a plurality of E-CSCFs 30 each generate information for identifying its own device. Also, the information specifying the E-CSCF 30 generated in the E-CSCF 30 needs to be held in the MSC 70 when the UE 90 changes the connection destination by SRVCC. Therefore, in order to provide the information generated by the E-CSCF 30 to the MSC 70, the E-CSCF 30 transmits to the MME 50 holding information (profile information) related to the connection status of the communication terminal, and one of the profile information It is set as the structure held as. And when UE90 performs SRVCC, it is set as the structure which provides the information which specifies E-CSCF30 with respect to MSC70 from MME50. Further, the communication control system 1 has a feature in a transmission route for providing information specifying the E-CSCF 30 from the E-CSCF 30 to the MME 50. Specifically, even a roaming-in terminal such as the UE 90 described in the present embodiment is configured to be able to exchange information specifying the E-CSCF 30 only with a device included in the own system. .

  FIG. 3 is a diagram showing functional blocks for realizing the characteristic configuration in the communication control system 1 according to the present embodiment.

  As shown in FIG. 3, the E-CSCF 30 includes an E-STN-SR generation unit 31 (identification information generation unit / identification information transmission unit) and an E-STN-SR transmission destination determination unit 32 (determination unit). The MME 50 also includes a profile DB (database) (storage means) 51 and an E-STN-SR transmission unit 52 (identification information transfer means). Further, the MSC 70 includes an E-CSCF setting unit 71 (relay node setting unit).

  The E-STN-SR generation unit 31 of the E-CSCF 30 has a function of generating an E-STN-SR (Emergency Session Transfer Number for SRVCC). The E-STN-SR is an identifier (identification information) serving as information for specifying the E-CSCF 30 used when the UE 90 changes the connection destination from the LTE network N1 to the 3G network N2 by SRVCC during an emergency call. . The E-STN-SR is issued by the E-CSCF 30 when the UE 90 starts an emergency call. Moreover, it has a function which transmits E-STN-SR with respect to MME50 based on the determination result by the E-STN-SR transmission destination determination part 32. FIG.

  The E-STN-SR transmission destination determination unit 32 of the E-CSCF 30 has a function of determining a transmission path when transmitting the E-STN-SR to the MME 50. For example, when the UE 90 is a roaming-in terminal, it is necessary to adopt a configuration in which E-STN-SR is transmitted in the communication control system 1. Therefore, the transmission path of the E-STN-SR is determined based on the determination as to whether or not the terminal is a roaming-in terminal. Note that the E-STN-SR transmission destination determination unit 32 may not be provided. In this case, the transmission path for notifying the E-STN-SR can be set uniformly.

  The profile DB 51 of the MME 50 has a function of holding the E-STN-SR transmitted from the E-CSCF 30 in association with information for specifying the UE 90. An example of information held in the profile DB 51 is shown in FIG. FIG. 4 shows an example in which one sheet is prepared for each user. IMSI (International Mobile Subscriber Identity: user identification number), which is information for identifying the UE 90, and MSISDN (Mobile Subscriber ISDN Number: telephone). Number) is associated with Tracking Area List (location information list), MS Network Capability (network capability), and STN-SR (information specifying P-CSCF (Proxy-CSCF) used for normal calls). Yes. Furthermore, the profile DB 51 of the present embodiment is different from the conventional configuration in that E-STN-SR is also stored in association with information for specifying the UE 90.

  When the UE 90 performs SRVCC, the E-STN-SR transmission unit 52 of the MME 50 converts the E-STN-SR stored in the profile DB 51 in association with information specifying the UE 90 based on an instruction from the eNB 46. It has the function to transmit to.

  The E-STN-SR stored in the profile DB 51 is stored when the UE 90 starts an emergency call. Further, when the UE 90 ends the emergency call, the E-STN-SR is deleted based on an instruction related to the process for deleting the communication path related to the emergency call. Instead of deleting the E-STN-SR, the E-STN-SR may be overwritten at the start of the next emergency call.

  The E-CSCF setting unit 71 of the MSC 70 has a function of specifying and setting the E-CSCF 30 used by the UE 90 based on the E-STN-SR transmitted from the MME 50. As a result, the MSC 70 can transmit a radio switching completion notification related to the UE 90 to the E-CSCF 30 used by the UE 90, and can continue communication related to the emergency call using the 3G network N2.

  Next, a method for notifying the E-STN-SR from the E-CSCF 30 to the MME 50 will be described with reference to FIG. The notification of E-STN-SR from the E-CSCF 30 is performed simultaneously when the UE 90 makes an emergency call. When the UE 90 starts an emergency call, first, the UE 90 issues a location registration request to the E-CSCF 30A via the eNB 46, the S-GW 44, and the P-GW 42 (solid line L4 in FIG. 5). On the other hand, in the E-CSCF 30A, the E-STN-SR generation unit 31 generates an E-STN-SR that identifies the E-CSCF 30A.

  When notifying the MME of the E-STN-SR, the E-STN-SR 30A notifies the MME 50 via the PCRF 40, the P-GW 42, and the S-GW 44 (solid line L5 in FIG. 5). Thereby, E-STN-SR is notified with respect to MME50. Then, when the UE 30 changes the connection destination from the LTE network N1 to the 3G network N2, the E-STN-SR to which the UE 90 is connected is notified from the MME 50 to the MSC 70 in the process related to SRVCC. Therefore, the MSC 70 can identify the E-CSCF 30 to which the UE 90 is connected based on the E-STN-SR (broken line L6 in FIG. 5).

  Next, with reference to FIG. 6 and FIG. 7, signal exchange when the connection destination is changed by SRVCC when the UE 90 is making an emergency call will be described.

  First, a process related to E-STN-SR notification when establishing a connection related to an emergency call will be described with reference to FIG. When the UE 90 establishes an emergency call, first, if the Attach process (S01) is not performed, this is performed, and then the bearer (Emergency Default Bearer) for establishing the emergency call communication path is established. Processing is performed (S02). Thereafter, an emergency call location registration request (SIP_REGISTER / REGTYPE: SOS) is transmitted from the UE 90 to the E-CSCF 30 (S03). Although the communication control system 1 includes a plurality of E-CSCFs 30, the E-CSCF 30 used by the UE 90 may be configured to be selected on the system side or may be configured to be selectable by the UE 90.

  The E-CSCF 30 that has received the location registration request determines whether or not the UE 90 is a roaming-in terminal (S04). A location registration request (SIP_REGISTER / REGTYPE: SOS) related to the UE 90 is transmitted to the S-CSCF 20X of the operator (S05). This location registration request (SIP_REGISTER / REGTYPE: SOS) is transmitted to the AS 10X (S06), and then a registration process (Emergency Registration) related to an emergency call is performed (S07).

  On the other hand, the UE 90 transmits a signal (SIP_INVITE) requesting establishment of an emergency call voice bearer to the E-CSCF 30 (S08). In the E-CSCF 30, when the E-STN-SR generation unit 31 generates the E-STN-SR based on this signal, the signal (Diameter_AAR) including information identifying the UE 90 and the E-STN-SR is transmitted to the PCRF 40. It transmits to (S09). When this signal (Diameter_AAR) is transmitted from the PCRF 40 to the P-GW 42 (S10), a request signal (GTPv2_Create Bearer Request) related to establishment of a communication path (bearer) is transmitted from the P-GW 42 to the S-GW 44. (S11). This signal includes E-STN-SR. Then, this signal is transmitted from the S-GW 42 to the MME 50 (S12), whereby the MME 50 can receive the E-STN-SR. And MME50 can hold | maintain the information (E-STN-SR) which specifies E-CSCF30 which UE90 uses by updating profile DB51 of MME50 (S13).

  Thereafter, the processing related to the establishment of the emergency call communication path (Emergency Dedicated Bearer) is continued (S14), and after the communication path is opened, the emergency call by the UE 90 is started.

  Next, processing related to SRVCC during an emergency call will be described with reference to FIG. It is assumed that the UE 90 is in an emergency call using the LTE network N1 (S21). Here, when the radio quality in the LTE network N1 deteriorates due to movement of the UE 90 or the like (S22), the eNB 46 transmits a request signal (S1-AP_Handover Required) for changing the connection destination to the MME 50 (S23). The MME 50 transmits an SRVCC request (GTPv2_SRVCC PS to CS Request) related to the UE 90 to the MSC 70 (S24). At this time, the MME 50 refers to the profile DB 51 and attaches E-STN-SR, which is information for specifying the E-CSCF 30 to which the UE 90 is connected, to the above signal.

  When receiving the above signal from the MME 50, the MSC 70 refers to the E-STN-SR included in the signal and the E-CSCF setting unit 71 selects and sets the E-CSCF 30 when performing processing related to the UE 90. (S25). Thereafter, when a radio switching request (RANAP_SCCP Connection Setup Request) is transmitted from the MSC 70 to the RNC 80 (S26), a completion report signal (RANAP_Relocation Complete) is transmitted from the RNC 80 to the MSC 70 after performing predetermined processing in the RNC 80. (S27).

  The MSC 70 transmits a radio switching completion notification (SIP_INVITE) to the E-CSCF 30 set in advance (S25) (S28). When the E-CSCF 30 responds to the MSC 70 (SIP_200 OK) (S29), a radio switching completion notification (SIP_INFO) is transmitted to the S-CSCF 20X of the overseas telecommunications carrier with which the UE 90 is contracted (S30). . Based on this, signals (SIP_INFO, SIP_200 OK) are transmitted and received between the S-CSCF 20X and the AS 10X (S31, S32), and a response signal (SIP_200 OK) is transmitted from the S-CSCF 20X to the E-CSCF 30. (S33). Thereby, the process related to the communication path establishment for SRVCC is completed, and the process related to SRVCC is continued (S34).

  As described above, in the communication control system 1 according to the present embodiment, a plurality of E-CSCFs 30 can be installed. As described above, in the conventional communication control system, it is assumed that one E-CSCF 30 as an emergency call relay node is installed in the network. Therefore, an emergency call is appropriately performed at the time of failure or when the processing load increases. There was a possibility that the call could be lost or the service could be interrupted. On the other hand, in the communication control system 1, an emergency call using the E-CSCF 30 can be suitably performed even when a failure occurs by adopting a configuration including a plurality of E-CSCFs 30.

  In the communication control system 1, when introducing a plurality of E-CSCFs 30, the E-CSN 30 is configured to generate E-STN-SR, which is information for identifying the E-CSCFs 30, and the profile DB 51 of the MME 50 is used. The E-STN-SR is held, and the E-STN-SR is notified to the MSC 70 that is a processing apparatus related to radio switching. In the conventional communication control system, since a configuration in which a plurality of E-CSCFs are provided is not assumed, even when the UE during emergency call communication changes the connection destination by SRVCC, the E- utilized for UE communication The CSCF was uniquely identified. Therefore, simply adding a plurality of E-CSCFs to the conventional communication control system cannot identify the E-CSCF used by the UE in the MSC. On the other hand, the E-STN-SR is generated by the E-CSCF 30 and notified to the MSC 70 via the MME 50, so that the E-STN-SR is selected from a plurality of E-CSCFs. The MSC 70 can specify the E-CSCF 30 to be connected.

  Further, the communication control system 1 is configured such that when the E-STN-SR is notified to the MME 50, the roaming-in terminal does not pass through a device on the overseas telecommunications carrier side used when making an emergency call. Specifically, as a route for avoiding AS10X, S-CSCF20, and HSS60X provided by an overseas telecommunications carrier, E-CSCF30 is connected to MME50 via PCRF40, P-GW42, and S-GW44. It was set as the structure which notifies STN-SR. The communication control device configured by the PCRF 40, the P-GW 42, and the S-GW 44 is configured so that the roaming-in terminal performs communication using the LTE network N1 in the communication control system 1 by using a device on the communication control system 1 side. It is necessary to use.

  Therefore, even if the UE 90 is a roaming-in terminal, the E-STN-SR can be notified to the MME 50 via a device included in the communication control system 1. If the handling of E-STN-SR is not stipulated because the telecommunications carriers are different, suppose that E-STN-SR is used for a device of a system different from the own system (system provided by a different telecommunications carrier). If transmitted, the E-STN-SR may not be properly processed. Therefore, it is conceivable that the MSC 70 cannot acquire the E-STN-SR and cannot properly connect to the E-CSCF 30. According to the notification method to the MME 50 by the communication control system 1 of the present embodiment, since the processing can be completed within the own system 1, the notification of the E-STN-SR to the MME 50 and the storage at the MME 50 are ensured. It can be carried out.

(Second Embodiment)
As a second embodiment of the communication control system according to the present invention, when the E-CSCF transmits the E-STN-SR to the MME, there are a plurality of E-STN-SR transmission paths, and the E-CSCF A configuration for determining a transmission route and performing processing will be described.

  FIG. 8 is a diagram for explaining processing in the communication control system 1A according to the second embodiment. The configuration of the communication control system 1A is the same as that of the communication control system 1 according to the first embodiment. However, it is assumed that UE 90A is not a roaming-in terminal but a communication terminal contracted with a communication carrier that provides communication control system 1A. In this case, when voice communication is performed via the LTE network N1 or the 3G network N2, it is not necessary to communicate with an external system device like a roaming-in terminal, and everything can be completed within the communication control system 1. it can.

  When the UE 90A as described above starts an emergency call, first, the UE 90A makes a location registration request to the E-CSCF 30A via the eNB 46, the S-GW 44, and the P-GW 42 (solid line L7 in FIG. 8). On the other hand, in the E-CSCF 30A, the E-STN-SR generation unit 31 generates an E-STN-SR that identifies the E-CSCF 30A. Up to this point, the process is the same as in the first embodiment.

  Here, when the E-STN-SR is notified to the MME, the E-CSCF 30A notifies the MME 50 via the PCRF 40, the P-GW 42, and the S-GW 44 as shown in the first embodiment (see FIG. 8 dash-dot line L8). However, as another transmission route, a route (broken line L9 in FIG. 8) of notifying the MME 50 from the E-CSCF 30 via the S-CSCF 20, the AS 10, and the HSS 60 can also be used.

  When the UE 90 is not a roaming-in terminal but a communication terminal contracted with a communication carrier of the communication control system 1A, the route via the S-CSCF 20, AS 10 and HSS 60 (first route) This is the same as the signal path related to the start processing when a call is made. Therefore, by attaching the E-STN-SR to the signal related to the emergency call start process, the E-STN-SR can be transmitted to the MME 50 without increasing new communication.

  However, the E-STN-SR cannot be transmitted through the first route due to an increase in the processing load of the AS 10 or the like, an increase in the processing load of the HSS 60, or the occurrence of a network failure between the MME 50 and the HSS 60. Conceivable. Therefore, as the second route, the configuration is such that the MME 50 is notified via the PCRF 40, the P-GW 42, and the S-GW 44 as in the first embodiment, so that the E-STN-SR can be reliably transmitted to the MME 50. You can be notified.

  Further, when the E-STN-SR is transmitted to the MME 50 via the AS 10 or the like through the first route, the E-CSCF 30A determines whether the E-STN-SR can be transmitted to the MME 50. It is also possible to adopt a configuration to The method for determining whether or not the E-STN-SR can be properly processed is, for example, whether or not an error is notified from the S-CSCF 20 to the E-CSCF 30A, or the processing completion is notified from the S-CSCF 20 Or not. When it is determined that the E-STN-SR cannot be transmitted to the MME 50 by the first route passing through the AS 10 or the like, the E-STN-SR transmission destination determination unit 32 of the E-CSCF 30A sets the second route, That is, the transmission of E-STN-SR along the route indicated by the broken line L9 in FIG. 8 is designated, and the E-STN-SR is newly transmitted from the E-CSCF 30A to the MME 50. Thereby, it becomes possible to notify the MME 50 of E-STN-SR more reliably.

  In FIG. 9, the process in the case of notifying the MME 50 of the E-STN-SR via the S-CSCF 20, the AS 10, and the HSS 60 will be described.

  When the UE 90 establishes an emergency call, first, if the Attach process (S41) is not performed, this is performed, and then the establishment of a bearer (Emergency Default Bearer) for establishing an emergency call communication path Processing is performed (S42). Thereafter, an emergency call location registration request (SIP_REGISTER / REGTYPE: SOS) is transmitted from the UE 90 to the E-CSCF 30 (S43).

  In the E-CSCF 30 that has received the location registration request, after confirming that the UE 90 is not a roaming-in terminal, the location registration request for the UE 90 to the S-CSCF 20 of its own system, which is a communication carrier with which the UE 90 is contracted ( SIP_REGISTER / REGTYPE: SOS) is transmitted (S44). At this time, E-STN-SR is attached.

  This location registration request (SIP_REGISTER / REGTYPE: SOS) is transmitted to the AS 10 (S45), and then a location registration processing request (MAP_Update Location) related to the emergency call of the UE 90 is transmitted to the HSS 60 (S46). Since E-STN-SR is also attached at this time, E-STN-SR is notified to HSS 60. When the HSS 60 responds to the location registration processing request from the AS 10 (MAP_Update Ack) (S47), it is notified to the S-CSCF 20 that the processing has been completed by the AS 10 (SIP_200 OK) (S48), and the S-CSCF 20 Communication is performed to the E-CSCF 30A (S49).

  On the other hand, the E-CSCF 30A is in an error determination standby state (S50). In the error determination standby state, when it is determined that the transmission of the E-STN-SR is an error based on the flow shown in FIG. 10, the MME 50 is notified via the PCRF 40, the P-GW 42, and the S-GW 44. It has a configuration. Specifically, after transmitting a location registration request (SIP_REGISTER / REGTYPE: SOS) related to the UE 90 to the S-CSCF 20 (corresponding to S61: S44), it is determined whether or not an error is notified (S62). Is notified, the E-STN-SR is notified to the PCRF 40 (S63). Further, even when no error is notified, it is determined whether or not a preset standby time has elapsed (timeout) (S64), and when timed out, E-STN-SR is notified to the PCRF 40 (S65).

  Here, the notification of the E-STN-SR to the PCRF 40 (S63, S65) is the transmission of the signal (Diameter_AAR) including the information identifying the UE 90 and the E-STN-SR in FIG. 6 to the PCRF 40 (S08). Is the same process. When this processing is performed, a series of processing (S09 to S12) related to the signal (Diameter_AAR) in FIG. 6 is performed, so that the profile DB 51 of the MME 50 is updated and information (E-CSCF 30 used by the UE 90) is specified ( E-STN-SR) can be held by the MME 50.

  On the other hand, when processing is performed via the route via the AS 10, when the E-CSCF 30A receives a completion notification from the S-CSCF 20 (S49), a completion notification (SIP_200 OK) is transmitted from the E-CSCF 30A to the UE 90. (S51). Moreover, the signal (Diameter_IDR) containing the information which specifies UE90, and E-STN-SR is transmitted with respect to MME50 from HSS60 (S52). MME50 can receive E-STN-SR which concerns on UE90 by receiving this signal. Then, the profile DB 51 of the MME 50 is updated (S53), and a response signal (Diameter_IDR) is transmitted to the HSS 60. Through the above processing, the MME 50 can hold information (E-STN-SR) that specifies the E-CSCF 30 used by the UE 90.

  The process when the UE 90 changes the connection destination from the LTE network N1 to the 3G network N2 by SRVCC is the same as that of the first embodiment.

  As described above, in the communication control system 1A according to the present embodiment, the E-STN-SR can be transmitted to the MME 50 via the first route via the AS or the like, which is conventionally performed. Since it becomes possible to notify the E-STN-SR to the MME 50 using a part of the communication related to location registration, the E-STN-SR is notified to the MME 50 while preventing an increase in the traffic. It becomes possible. On the other hand, when the first route cannot be used (the E-STN-SR cannot be notified using the first route), the second route via the communication control device (PCRF or the like) is used. By providing a configuration for notifying the MME 50 of the E-STN-SR, the E-STN-SR can be reliably notified to the MME 50. Therefore, even when the UE 90 performs SRVCC, the E-CSCF 30 to which the UE 90 is connected can be appropriately selected from the plurality of E-CSCFs 30.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be modified in various ways as described below without departing from the scope of the invention.

  For example, the plurality of E-CSCFs 30A to 30C included in the communication control systems 1 and 1A in the above embodiment may be configured integrally with a P-CSCF (Proxy-CSCF), respectively. The P-CSCF is a relay node related to a normal call connection, not an emergency call. Since the P-CSCF and the E-CSCF have many common functions, they can be easily integrated. Since a plurality of P-CSCFs have been conventionally arranged in the communication control system, a plurality of E-CSCFs are arranged in the system by giving the P-CSCF functions as the E-CSCF. Can be easily realized.

  In addition, when a plurality of P-CSCFs and E-CSCFs are arranged as a single unit, for example, it is possible for the P-CSCF to use E-CSCF resources with a very small call volume during normal times. .

  Moreover, although the said embodiment demonstrated the case where a relay node was E-CSCF30 (emergency call relay node), the structure which concerns on the said embodiment is applicable also to P-CSCF, for example. That is, the present invention is not limited to the emergency call relay node, but can also be applied to a normal call relay node.

  Moreover, although the said embodiment demonstrated the case where UE90 moved with respect to the 3G network N2 from the LTE network N1, it is not limited to said network.

  Also, in the above, as the first embodiment, the configuration for transmitting the E-STN-SR related to the UE 90 that is a roaming-in terminal to the MME 50 via the PCRF 40 or the like will be described, and as the second embodiment, the roaming Regarding the E-STN-SR related to the UE 90 that is not an in-terminal, the configuration has been described in which the E-STN-SR is transmitted to the MME 50 via the AS 10 or the like. These may be combined. Specifically, there is a method for notifying whether or not the UE 90 is a roaming-in terminal and notifying the E-STN-SR via a route that passes through the AS 10 or the like as in the second embodiment. Can be mentioned. At this time, if the S-CSCF 20X cannot handle the E-STN-SR because of an external device, such as a roaming-in terminal, an error is returned. In that case, the PCRF 40 in the own system is A configuration in which the E-STN-SR is transmitted to the MME 50 via a route that passes through may be employed. Even with such a configuration, it is possible to reliably notify the MME 50 of the E-STN-SR for identifying the E-CSCF 30.

  DESCRIPTION OF SYMBOLS 1,1A ... Communication control system, 10 ... AS, 20 ... S-CSCF, 30 ... E-CSCF, 40 ... PCRF, 42 ... P-GW, 44 ... S-GW, 46 ... eNB, 50 ... MME, 60 ... HSS, 70 ... MSC, 80 ... RNC, 90 ... UE.

Claims (4)

A communication terminal connectable to the first communication network and the second communication network continues from the first communication network to the second communication network in a state in which the voice communication with the application server providing the voice communication service is continued. A communication control system for controlling communication of the communication terminal when changing a connection destination,
A plurality of relay nodes capable of relaying signals related to voice communication by the communication terminal;
A communication control device for controlling communication of the communication terminal using the first communication network;
A terminal management device for managing a connection status of the communication terminal in the first communication network;
A circuit switching device for controlling circuit switching from the first communication network to the second communication network;
With
The relay node is
Identification information generating means for generating identification information for identifying the device itself;
The identification information generated by the identification information generation means is associated with information for identifying the communication terminal for which the own device relays a signal, and is transmitted to the terminal management device via the communication control device. Identification information transmitting means for transmitting
The terminal management device
Storage means for storing identification information of the relay node that relays a signal related to voice communication of the communication terminal in association with information for specifying the communication terminal;
Identification information transfer means for transmitting the identification information stored in the storage means to the circuit switching device,
The circuit switching device
Relay node setting means for selecting a relay node that relays voice communication of the communication terminal from the plurality of relay nodes based on the identification information transmitted from the terminal management device and performing circuit switching related to the communication terminal A communication control system comprising: The relay node is
Determining means for designating a transmission path for transmitting the identification information generated by the identification information generating means to the terminal management device;
The communication control system according to claim 1, wherein the identification information transmission unit changes a transmission path for transmission to the terminal management device based on designation by the determination unit.   The communication control system according to claim 2, wherein when the communication terminal is a roaming-in terminal, the determination unit specifies a transmission path that passes through the communication control device.   The determination means uses a transmission path that passes through the communication control apparatus when the transmission path that does not pass through the communication control apparatus is a first path and the identification information cannot be transmitted through the first path. The communication control system according to claim 2, wherein the communication control system is designated.

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