JP5020835B2 - Communication control server, communication system, and communication control method - Google Patents

Description

  The present invention relates to a communication control server, a communication system, and a communication control method.

Recently, a network technology called IMS (IP Multimedia Subsystem) has been developed. The IMS network includes a plurality of SIP servers, HSS (Home Subscriber Server), and the like that transmit and receive SIP messages (SIP: Session Initiation Protocol). The SIP server is a S-CSCF (Serving-Call / Session Control Function) as a communication control server that performs communication control of a mobile communication terminal, or a P-CSCF as a communication connection server that connects a mobile communication terminal to the S-CSCF. (Proxy-Call / SessionControlFunction). Such a technology related to the IMS network is described in, for example, Patent Document 1.
JP 2006-115453 A

  Meanwhile, a plurality of mobile communication terminals access the S-CSCF via the P-CSCF. For this reason, when the access of the mobile communication terminal is concentrated on a specific S-CSCF, the processing load of the S-CSCF increases, and there is a possibility that a communication failure occurs.

  Therefore, an object of the present invention is to provide a communication control server, a communication system, and a communication control method that can avoid the occurrence of a communication failure accompanying an increase in processing load.

  The present invention is a communication control server that controls communication of a plurality of mobile communication terminals, and when detecting means for detecting congestion of the communication control server and congestion of the communication control server are detected by the detecting means, Identifying means for identifying a waiting mobile communication terminal among the plurality of mobile communication terminals controlled by the communication control server, and communication control for the mobile communication terminal identified by the identifying means for detecting the congestion And a first transmission means for transmitting a transfer request to be performed in place of the control server to a communication control server other than the communication control server.

  Further, the present invention is a communication system comprising the communication control server and another communication control server that receives a transfer request for transferring a mobile communication terminal controlled by the communication control server from the communication control server. The other communication control server includes a receiving unit that receives the transfer request, and a communication management server that manages the mobile communication terminal and the mobile communication terminal when the transfer unit receives the transfer request. The communication control server that performs communication control of the mobile communication terminal that is the target of transfer in the transfer request received by the receiving unit with respect to the communication connection server that is connected to and communicates with one communication control server. And a second transmission means for transmitting a change request to change to

  Further, the present invention is a communication control method using a communication control server for controlling communication of a plurality of mobile communication terminals, wherein a detection step of detecting congestion of the communication control server, and the communication control server in the detection step When the congestion is detected, a specifying step for specifying a waiting mobile communication terminal among the plurality of mobile communication terminals controlled by the communication control server, and communication control for the mobile communication terminal specified in the specifying step And a transmission step of transmitting a transfer request to the effect that it is performed in place of the communication control server in which congestion is detected to a communication control server other than the communication control server.

  According to the present invention, the communication control server determines whether or not the own device is congested. When the own device is congested, the mobile communication terminal that is waiting among the mobile communication terminals that control the communication of the own device is changed. To the communication control server. Thereby, since the congestion state of the communication control server is avoided, it is possible to avoid the occurrence of a communication failure due to the concentration of the processing load of the specific communication control server.

  In the present invention, whether another communication control server that can be connected to the mobile communication terminal via the communication connection server that connects the mobile communication terminal specified by the specifying means to the communication control server is congested. If there is a determination means for determining whether or not there is one communication control server determined to be non-congested by the determination means, the mobile communication indicates that the communication control for the mobile communication terminal specified by the specifying means is to be transferred. The information processing apparatus further includes a communication management server that manages the terminal and a notification unit that notifies the communication connection server, and the first transmission unit may transmit a transfer request to one communication control server.

  Further, the communication system of the present invention includes a communication control server having the determination means and the notification means, another determined communication control server determined not to be congested by the communication control server, and the two communication control servers. And a communication management server for managing the mobile communication terminal, wherein the determined communication control server is a mobile communication controlled by the communication control server. A first receiving means for receiving a transfer request for transferring the communication terminal from the communication control server; and when the transfer request is received by the first receiving means, the mobile terminal moves to the communication connection server and the communication management server. And a second transmission means for transmitting a change request for changing the communication control server for controlling the communication terminal to the determined communication control server. Each of the server and the communication management server includes a second receiving unit that receives a transfer notification indicating transfer of the mobile communication terminal, a third receiving unit that receives a change request, and a second receiving unit. When the notification is received, it is also possible to have stop means for stopping the processing for the mobile communication terminal until the third receiving means receives the change request.

  According to the present invention, it is possible to provide a communication control server, a communication system, and a communication control method that can avoid the occurrence of a communication failure accompanying an increase in processing load.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, if possible, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the communication system 1 includes a mobile communication terminal 2a, a mobile communication terminal 2b, a P-CSCF 4 (communication connection server), an S-CSCF (A) 61 (communication control server), and an S-CSCF (B). This is an IMS system including 62 (communication control server) and HSS8 (HSS: Home Subscriber Server) (communication management server). The mobile communication terminal 2a and the mobile communication terminal 2b perform wireless communication with the P-CSCF 4, and the P-CSCF 4 performs wired communication (or wireless communication) with the S-CSCF (A) 61 and the S-CSCF (B) 62, The HSS 8 performs wired communication (or wireless communication) with the S-CSCF (A) 61 and the S-CSCF (B) 62. Further, the S-CSCF (A) 61 and the S-CSCF (B) 62 perform wired communication (or wireless communication).

  Note that the number of mobile communication terminals such as the mobile communication terminal 2a and mobile communication terminal 2b included in the communication system 1, the number of P-CSCFs such as P-CSCF4, S-CSCF (A) 61 and S-CSCF (B) 62. The number of S-CSCFs such as HSS and the number of HSSs such as HSS8 are not limited to those shown in FIG. The mobile communication terminal 2a and the mobile communication terminal 2b have the same configuration, and the S-CSCF (A) 61 and the S-CSCF (B) 62 have the same configuration. This will be described using the mobile communication terminal 2a and the S-CSCF (A) 61.

  The mobile communication terminal 2a is a mobile communication terminal such as a mobile phone. The mobile communication terminal 2a performs location registration with the S-CSCF such as the S-CSCF (A) 61 via the P-CSCF4. The P-CSCF 4 is a SIP server that communicatively connects a mobile communication terminal such as the mobile communication terminal 2 a to an S-CSCF such as the S-CSCF (A) 61. The P-CSCF 4 has subscriber information of a mobile communication terminal such as the mobile communication terminal 2a whose location is registered and controlled by the S-CSCF such as the S-CSCF (A) 61 (subscriber information 12 shown in FIG. 4). See). The subscriber information possessed by the P-CSCF 4 includes the telephone number of a mobile communication terminal such as the mobile communication terminal 2a, and the S-CSCF (A) 61 that performs location registration and communication control for the mobile communication terminal such as the mobile communication terminal 2a. Are associated with the address of the S-CSCF.

  The S-CSCF (A) 61 is a SIP server that performs location registration of a mobile communication terminal such as the mobile communication terminal 2a and controls communication of the mobile communication terminal such as the mobile communication terminal 2a. The S-CSCF (A) 61 has subscriber information of a mobile communication terminal such as the mobile communication terminal 2a that performs location registration and communication control. The subscriber information possessed by the S-CSCF (A) 61 includes the telephone number of the mobile communication terminal such as the mobile communication terminal 2a and the mobile communication terminal such as the mobile communication terminal 2a connected to the S-CSCF (A) 61. The address of the P-CSCF 4 is associated with each other, and as shown in FIG. 7, the current call state (during a call or waiting), the last call time, etc. for each telephone number of the mobile communication terminal such as the mobile communication terminal 2a It has the information which shows.

  The HSS 8 manages a mobile communication terminal such as the mobile communication terminal 2a (manages subscriber information). The HSS 8 has subscriber information of a mobile communication terminal such as the mobile communication terminal 2a controlled by the S-CSCF such as the S-CSCF (A) 61. The subscriber information possessed by the HSS 8 includes the telephone number of a mobile communication terminal such as the mobile communication terminal 2a, and the S-CSCF (A) 61 that performs location registration and communication control for the mobile communication terminal such as the mobile communication terminal 2a. Associated with the address of the S-CSCF.

  Next, the configuration of the P-CSCF 4 will be described with reference to FIGS. First, the configuration of the P-CSCF 4 will be described with reference to FIG. The P-CSCF 4 physically includes a CPU 4a, a RAM 4b, a ROM 4c, an input device 4d, an output device 4e, a communication device 4f, and a recording device 4g, which are connected to a bus 4h. The CPU 4a centrally controls the P-CSCF 4 by loading predetermined computer software stored in a built-in memory such as the ROM 4c into the RAM 4b and executing it.

  The input device 4d is a data input device and outputs input data to the CPU 4a. The output device 4e is a display device such as an LCD, and displays data input from the CPU 4a on the LCD or the like. The communication device 4 f has an interface for communicating with a mobile communication terminal such as the mobile communication terminal 2 a and an S-CSCF such as the S-CSCF (A) 61. The recording device 4g stores computer software executable by the CPU 4a. The recording device 4g stores the subscriber information 12 shown in FIG.

  Here, the subscriber information 12 will be described with reference to FIG. The subscriber information 12 includes telephone number information 12a and S-CSCF address information 12b. The subscriber information 12 includes the telephone number of the mobile communication terminal such as the mobile communication terminal 2a shown in the telephone number information 12a and the mobile communication terminal such as the mobile communication terminal 2a shown in the S-CSCF address information 12b. An address of an S-CSCF such as an S-CSCF (A) 61 that performs registration and communication control is associated. For example, the subscriber information 12 is associated with the telephone number of the mobile communication terminal 2a and the address of the S-CSCF (A) 61 that performs location registration and communication control for the mobile communication terminal 2a. The telephone number of the mobile communication terminal 2b is associated with the address of the S-CSCF (A) 61 that performs location registration and communication control for the mobile communication terminal 2b.

  With reference to FIG. 3, the description of the configuration of the P-CSCF 4 will be continued. The CPU 4a realizes a plurality of functions shown in FIG. That is, the P-CSCF 4 functionally includes a receiving unit 41 and a changing unit 42. The receiving unit 41 and the changing unit 42 are functions realized when the CPU 4a executes computer software and operates each component of the P-CSCF 4 shown in FIG. In particular, the CPU 4a uses the receiving unit 41 and the changing unit 42 to execute processing performed by the P-CSCF 4 shown in FIG.

  The receiving unit 41 receives, from the changed S-CSCF, a request for changing the S-CSCF such as the S-CSCF (A) 61 that performs location registration and communication control for the mobile communication terminal such as the mobile communication terminal 2a. This change request is sent to the recording device 4g of the P-CSCF 4 according to the transfer of the mobile communication terminal from one S-CSCF (S-CSCF before change) to another S-CSCF (S-CSCF after change). Is a request to change the contents of the subscriber information 12 recorded in the above (namely, the address of the S-CSCF). When the request for changing the S-CSCF is received by the receiving unit 41, the changing unit 42 responds to the content of the subscriber information 12 recorded in the recording device 4g of the P-CSCF 4 (the address of the S-CSCF). ).

  Next, the configuration of the S-CSCF (A) 61 will be described with reference to FIGS. Since the configuration of the S-CSCF (B) 62 is the same as that of the S-CSCF (A) 61, it is omitted. First, the configuration of the S-CSCF (A) 61 will be described with reference to FIG. The S-CSCF (A) 61 physically includes a CPU 61a, a RAM 61b, a ROM 61c, an input device 61d, an output device 61e, a communication device 61f, and a recording device 61g, which are connected to a bus 61h. . The CPU 61a centrally controls the S-CSCF (A) 61 by loading predetermined computer software stored in a built-in memory such as the ROM 61c into the RAM 61b and executing it.

  The input device 61d is a data input device, and outputs input data to the CPU 61a. The output device 61e is a display device such as an LCD, and displays data input from the CPU 61a on the LCD or the like. The communication device 61 has an interface for communicating with other S-CSCF (S-CSCF (B) 62), P-CSCF4, HSS8, and the like. The recording device 61g stores computer software executable by the CPU 61a. The recording device 61g stores the subscriber information 14 shown in FIG.

  Here, the subscriber information 14 will be described with reference to FIG. The subscriber information 14 includes telephone number information 14a, call state information 14b, and last call time information 14c, and information (not shown) indicating the address of the P-CSCF such as the P-CSCF4. The subscriber information 14 includes the telephone number of the mobile communication terminal such as the mobile communication terminal 2a shown in the telephone number information 14a, and the call status of the mobile communication terminal such as the mobile communication terminal 2a shown in the call status information 14b (during a call, waiting, etc.) Communication state), the end time of the last call of the mobile communication terminal such as the mobile communication terminal 2a shown in the last call time information 14c, and the mobile communication terminal such as the mobile communication terminal 2a are connected to the S-CSCF (A) 61. Information indicating the address of the P-CSCF 4 to be associated with each other.

  For example, the subscriber information 14 includes the telephone number of the mobile communication terminal 2a, the call state of the mobile communication terminal 2a (during a call), and the end time of the last call of the mobile communication terminal 2a (15:00 on February 1, 2007). 00 minutes), the telephone number of the mobile communication terminal 2b, the call state of the mobile communication terminal 2b (waiting), and the end time of the final call of the mobile communication terminal 2b (February 2, 2007). Day 19:30). Note that the subscriber information 14 is updated by the CPU 61a using a trigger at the start or end of a call of a mobile communication terminal such as the mobile communication terminal 2a as a trigger or periodically.

  Next, the description of the configuration of the S-CSCF (A) 61 will be continued with reference to FIG. The CPU 61a realizes a plurality of functions shown in FIG. That is, the P-CSCF 61 functionally includes a detection unit 6a (detection unit), a specification unit 6b (specification unit), a first transmission unit 6c (first transmission unit), a reception unit 6d (reception unit), and a first unit. 2 transmitter 6e (second transmitter). The detection unit 6a to the second transmission unit 6e are functions realized when the CPU 61a executes computer software and operates each component of the S-CSCF (A) 61 illustrated in FIG. In particular, the CPU 61a uses the detection unit 6a to the second transmission unit 6e to execute processing performed by the S-CSCF (A) 61 illustrated in FIG.

  The detection unit 6a detects whether or not the own device (S-CSCF (A) 61) is congested. When the congestion of the own device is detected by the detecting unit 6a, the specifying unit 6b uses the subscriber information 14 to select a mobile communication terminal that is waiting among the mobile communication terminals such as the mobile communication terminal 2a that the own device controls communication. To identify. When the congestion of the own device is detected by the detection unit 6a, the first transmission unit 6c issues a transfer request for performing the communication control for the waiting mobile communication terminal specified by the specifying unit 6b instead of the own device. It transmits to other S-CSCF (for example, S-CSCF (B) 62) other than its own device. The receiving unit 6d receives a transfer request from another S-CSCF (for example, S-CSCF (B) 62).

  When the transfer request is received by the receiving unit 6d from the S-CSCF other than its own device, the second transmitting unit 6e transmits the transfer request in the transfer request received by the receiving unit 6d to the HSS 8 and the P-CSCF 4. Location registration and communication with a mobile communication terminal such as the mobile communication terminal 2a (identified as a target for transfer by the identification unit (corresponding to the identification unit 6b) of the S-CSCF that is the transmission source of the transfer request) A change request for changing the S-CSCF to be controlled from the S-CSCF that is a transmission source of the transfer request to the own device is transmitted. This change request is sent to the recording device 4g of the P-CSCF 4 according to the transfer of the mobile communication terminal from one S-CSCF (S-CSCF before change) to another S-CSCF (S-CSCF after change). Or the content of the subscriber information 12 recorded in the recording device 8g of the HSS 8 (that is, the address of the S-CSCF).

  Next, the configuration of the HSS 8 will be described (see FIGS. 2 and 3). The HSS 8 physically includes a CPU 8a, a RAM 8b, a ROM 8c, an input device 8d, an output device 8e, a communication device 8f, and a recording device 8g, which are connected to a bus 8h. The CPU 8a centrally controls the HSS 8 by loading predetermined computer software stored in a built-in memory such as the ROM 8c into the RAM 8b and executing it. The input device 8d is a data input device, and outputs input data to the CPU 8a.

  The output device 8e is a display device such as an LCD, and displays data input from the CPU 8a on the LCD or the like. The communication device 8f has an interface for communicating with an S-CSCF such as the S-CSCF (A) 61. The recording device 8g stores computer software executable by the CPU 8a. The recording device 8g stores the subscriber information 12 shown in FIG.

  The CPU 8a realizes a plurality of functions shown in FIG. That is, the HSS 8 functionally includes a receiving unit 81 and a changing unit 82. The receiving unit 81 and the changing unit 82 are functions realized by the CPU 8a executing computer software and operating the components of the HSS 8 shown in FIG. In particular, the CPU 8a uses the receiving unit 81 and the changing unit 82 to execute processing performed by the HSS 8 shown in FIG.

  The receiving unit 81 receives, from the changed S-CSCF, an S-CSCF change request such as S-CSCF (A) 61 that performs location registration and communication control for the mobile communication terminal such as the mobile communication terminal 2a. This change request is recorded in the recording device 8g of the HSS 8 in accordance with the transfer of the mobile communication terminal from one S-CSCF (S-CSCF before change) to another S-CSCF (S-CSCF after change). This is a request for changing the content of the subscriber information 12 (that is, the address of the S-CSCF). When the S-CSCF change request is received by the receiving unit 81, the changing unit 82 responds to the change request with the contents of the subscriber information 12 recorded in the recording device 8g of the HGG 8 (S-CSCF address). To change.

  Next, the operation of the communication system 1 will be described with reference to FIG. First, when the detection unit 6a of the S-CSCF (A) 61 detects congestion of the S-CSCF (A) 61 (step S1), the specifying unit 6b of the S-CSCF (A) 61 The mobile communication terminal that is waiting among the mobile communication terminals that 61 performs communication control is specified using the subscriber information 14 (hereinafter, the mobile communication terminal 2b in the subscriber information 14 shown in FIG. 7) (step S2).

  Thereafter, the first transmission unit 6c of the S-CSCF (A) 61 performs location registration and communication with a mobile communication terminal such as the waiting mobile communication terminal 2b specified by the specification unit 6b of the S-CSCF (A) 61. A transfer request for performing control in place of the S-CSCF (A) 61 is transmitted to other S-CSCFs (S-CSCF (B) 62) other than the S-CSCF (A) 61 (step S3). In this case, the first transmission unit 6c of the S-CSCF (A) 61 waits for the transfer request to be specified by the mobile communication terminal (the specifying unit 6b of the S-CSCF (A) 61) such as the mobile communication terminal 2b to which the transfer is requested. Of the mobile communication terminal) and the subscriber information 14 and the like.

  After step S3, the receiving unit 6d of the S-CSCF (B) 62 sends a transfer request together with the telephone number of the mobile communication terminal such as the mobile communication terminal 2b to be transferred and the subscriber information 14 to the S-CSCF ( A) When receiving from 61 (step S4), the second transmission unit 6e of the S-CSCF (B) 62 receives the reception unit of the S-CSCF (B) 62 from the HSS 8 that manages the S-CSCF (B) 62. Mobile communication of the mobile communication terminal 2b or the like that is the target of transfer in the transfer request received by 6d (specified as the transfer target by the specifying unit 6b of the S-CSCF (A) 61 that is the source of the transfer request) A change request for changing the S-CSCF that performs location registration and communication control to the terminal from the S-CSCF (A) 61 that is the transmission source of the transfer request to the S-CSCF (B) 62 is transmitted (S -Up S5).

  The S-CSCF (B) 62 communicates with the mobile communication terminal phone number such as the mobile communication terminal 2b to be transferred and the mobile communication terminal based on the contents of the received transfer request. The subscriber information recorded in its own recording device (corresponding to the recording device 61g) is changed using the address of the P-CSCF4.

  After Step S5, the receiving unit 81 of the HSS 8 performs S-CSCF (A-CSCF (A)) for performing location registration and communication control on a mobile communication terminal such as the mobile communication terminal 2b transferred from the S-CSCF (A) 61. ) A request for changing from 61 to S-CSCF (B) 62 is received from S-CSCF (B) 62, which is the S-CSCF after the change (step S6). When the receiving unit 81 receives the S-CSCF change request, the changing unit 82 of the HSS 8 changes the contents of the subscriber information 12 recorded in the recording device 8g of the HSS 8 ( That is, the address of the S-CSCF (A) 61 associated with the mobile communication terminal such as the mobile communication terminal 2b to be transferred is changed to the address of the S-CSCF (B) 62) (step S7). After step S7, the HSS 8 transmits to the S-CSCF (B) 62 an S-CSCF address change response indicating that the change of the content of the subscriber information 12 recorded in the recording device 8g of the HSS 8 has been completed. (Step S8). In step S3, the subscriber information (subscriber information 14) of the mobile communication terminal such as the mobile communication terminal 2b to be transferred is transmitted from the S-CSCF (A) 61 to the S-CSCF (B) 62. However, instead of this, in step S8, the subscriber information 12 stored in the recording device 8g may be transmitted by the HSS 8 to the S-CSCF (B) 62 together with the S-CSCF address change response or the like.

  After step S8, when the receiving unit 6d of the S-CSCF (B) 62 receives the S-CSCF address change response transmitted from the HSS 8 (step S9), the second transmitting unit of the S-CSCF (B) 62 6e sends a transfer request in the transfer request received by the receiving unit 6d of the S-CSCF (B) 62 to the P-CSCF 4 that communicatively connects a mobile communication terminal such as the mobile communication terminal 2b to the S-CSCF (B) 62. Location registration and communication control are performed with respect to a mobile communication terminal such as the mobile communication terminal 2b (specified by the specifying unit 6b of the S-CSCF (A) 61 that is the source of the transfer request). A change request for changing the S-CSCF from the S-CSCF (A) 61 that is the transmission source of the transfer request to the S-CSCF (B) 62 is transmitted (step S10).

  After step S10, the receiving unit 41 of the P-CSCF 4 converts the S-CSCF that performs location registration and communication control to the mobile communication terminal such as the mobile communication terminal 2b transferred from the S-CSCF (A) 61. A change request for changing from (A) 61 to S-CSCF (B) 62 is received from S-CSCF (B) 62 which is the changed S-CSCF (step S11). When the S-CSCF change request is received by the receiving unit 41, the changing unit 42 of the P-CSCF 4 responds to the change request and the contents of the subscriber information 12 recorded in the recording device 4g of the P-CSCF 4 (That is, the address of the S-CSCF (A) 61 associated with the mobile communication terminal 2b or the like to be transferred is changed to the address of the S-CSCF (B) 62) (step S12). After step S12, the P-CSCF 4 sends an S-CSCF address change response indicating that the change of the contents of the subscriber information 12 recorded in the recording device 4g of the P-CSCF 4 has been completed. 62 (step S13).

(Modification)
P-CSCF4, S-CSCF (A) 61, and HSS8 are not limited to those described above. The CPU 4a of the P-CSCF 4 and the CPU 8a of the HSS 8 may realize a plurality of functions shown in FIG. The function shown in FIG. 9 further includes a stop unit 43 (stop unit) in the case of P-CSCF4, and further includes a stop unit 83 (stop unit) in the case of HSS8, in addition to the function shown in FIG. The CPU 4a that realizes the function shown in FIG. 9 executes processing performed by the P-CSCF 4 shown in FIG. 12, and the CPU 8a that realizes the function shown in FIG. 9 executes processing executed by the HSS 8 shown in FIG. The receiving unit 41 (second receiving unit, third receiving unit) shown in FIG. 9 adds to the function of the receiving unit 41 described above, and is waiting for a mobile communication terminal (S-CSCF (S-CSCF)) specified by the specifying unit 6b. A) A mobile communication terminal that has been subjected to location registration and communication control from 61, hereinafter referred to as mobile communication terminal 2b) (from location registration and communication control for mobile communication terminal 2b) from S-CSCF (A) 61 Includes a function to receive notification of transfer (transfer notification).

  When the receiving unit 41 receives the transfer notification from the S-CSCF (A) 61, the stopping unit 43 receives the change request related to the transfer notification (that is, the S-CSCF that performs location registration and communication control for the mobile communication terminal 2b). -Processing for the mobile communication terminal 2b until the receiving unit 41 receives the S-CSCF address change request of the subscriber information 12 accompanying the transfer from the CSCF (A) 61 to the S-CSCF (B) 62 (Processing related to outgoing / incoming calls) is stopped. The functions of the receiving unit 81 (second receiving unit, third receiving unit), changing unit 82, and stopping unit 83 shown in FIG. 9 are the same as those of the receiving unit 41, changing unit 42, and the above-described FIG. This is the same as each function of the stop unit 43.

  Further, the CPU 61a of the S-CSCF (A) 61 may realize a plurality of functions shown in FIG. The function illustrated in FIG. 10 includes a determination unit 6f and a notification unit 6g in addition to the function illustrated in FIG. The CPU 61a that implements the function illustrated in FIG. 10 executes processing performed by the S-CSCF (A) 61 illustrated in FIG. The determination unit 6f determines whether another communication control server that can be connected to the mobile communication terminal 2b via the P-CSCF 4 is congested. The determination unit 6f performs this determination using the transfer destination management information 16 shown in FIG. 11 stored in advance in the memory of the S-CSCF (A) 61 such as the recording device 61g.

  If the detection unit 6a detects that the own device (S-CSCF (A) 6) is congested, the transfer destination management information 16 is created by the detection unit 6a and stored in a memory such as the recording device 61g. . The transfer destination management information 16 includes S-CSCF address information 16a and status information 16b. The S-CSCF address information 16a is an S-CSCF other than its own device (S-CSCF (A) 61), and can be communicably connected to the mobile communication terminal 2a, the mobile communication terminal 2b, etc. via the P-CSCF4. A plurality of addresses such as S-CSCF (B) 62 and S-CSCF (C) 63 are included. The state information 16b includes information indicating a communication state (whether or not currently congested) such as the S-CSCF (B) 62 and the S-CSCF (C) 63. The transfer destination management information 16 shown in FIG. 11 indicates that the S-CSCF (B) 62 is not congested and can be selected as a transfer destination to which the mobile communication terminal 2b is transferred, and the S-CSCF (C ) 63 is congested, indicating that the mobile communication terminal 2b cannot be selected as a transfer destination.

  The notification unit 6g notifies the P-CSCF 4 and the HSS 8 of the transfer of the mobile communication terminal 2b when there is one communication control server (S-CSCF (B) 62) that is determined not to be congested by the determination unit 6f. (Notification to transfer the mobile communication terminal 2b to another S-CSCF) is sent.

  Next, the operation of the communication system 1 in this modification will be described with reference to FIG. The sequence shown in FIG. 12 is obtained by adding steps S21 to S25 between steps S2 and S3 of the sequence shown in FIG. In the sequence shown in FIG. 12, the communication control server that is the transfer destination of the mobile communication terminal 2b is the S-CSCF (B) 62, as in the sequence shown in FIG.

  In the sequence shown in FIG. 12, after step S <b> 1, first, the detection unit 6 a is an S-CSCF other than its own device (S-CSCF (A) 61), and the mobile communication terminal 2 a or the mobile communication terminal 2 b and the P -The communication state (congestion or not) of other S-CSCFs that can be connected via CSCF 4 is detected, and transfer destination management information 16 indicating the detection result is created. After step S2, the specifying unit 6b uses the determination unit 6f to select one communication control server to be a transfer destination of the mobile communication terminal 2b based on the transfer destination management information 16 (step S21). When one communication control server (S-CSCF (B) 62), which is a transfer destination of the mobile communication terminal 2b, is selected by the specifying unit 6b in step S21, the notification unit 6g transfers the mobile communication terminal 2b. A transfer notification is sent to the P-CSCF 4 (step S22) and to the HSS 8 (step S24).

  This transfer notification is received by the receiving unit 41 of the P-CSCF 4 (step S23), and is also received by the receiving unit 81 of the HSS 8 (step S25). The execution timing of step S22 and the execution timing of step S24 are not limited to those shown in FIG. 12, and step S24 may be executed earlier than step S22, or both steps may be executed simultaneously.

  When the receiving unit 41 receives the transfer notification in step S23, the stopping unit 43 of the P-CSCF 4 waits until the S-CSCF address change request related to the transfer notification is received by the receiving unit 41 in step S11. Then, the process (communication connection) for the mobile communication terminal 2b related to the transfer notification is stopped. In addition, when the stop unit 83 of the HSS 8 receives the transfer notification by the receiving unit 81 in step S25, the request until the S-CSCF address change request related to the transfer notification is received by the receiving unit 81 in step S6. Then, the processing (notification of the location information (S-CSCF address, etc.)) for the mobile communication terminal 2b related to the transfer notification is stopped. When the stop unit 43 and the stop unit 83 have received a request to change the S-CSCF address before the predetermined time has elapsed after receiving the transfer notification from the S-CSCF (A) 61, the stop unit 43 and the stop unit 83 stop processing. To resume. Note that the S-CSCF that has received the connection request from the caller knows to which S-CSCF the call should be routed by making an inquiry to the HSS 8.

  If the stop unit 43 and the stop unit 83 have not received the S-CSCF address change request until a predetermined time has elapsed after receiving the transfer notification from the S-CSCF (A) 61, the transfer processing is performed. Is canceled, the suspension of the processing for the mobile communication terminal 2b is cancelled. After this cancellation (after the predetermined time has elapsed), the S-CSCF (A) 61 is connected to the mobile communication terminal 2b (when receiving a call request from the mobile communication terminal 2b from the P-CSCF 4), In step S3, the cancellation of the transfer request transmitted to the S-CSCF (B) 62 is notified to the S-CSCF (B) 62. It is assumed that the S-CSCF (B) 62 transmits a request for changing the S-CSCF address to the P-CSCF 4 and the HSS 8 before receiving the cancellation notification of the transfer request. In such a case, The S-CSCF (B) 62 notifies the P-CSCF 4 and the HSS 8 of cancellation of the already transmitted S-CSCF address change request.

  Next, operations and effects of the communication system 1 according to the embodiment will be described. The S-CSCF (A) 61 according to the embodiment is a communication control server that controls communication of a plurality of mobile communication terminals 2a and the like. The S-CSCF (A) 61 includes a detection unit 6a, a specification unit 6b, a first transmission unit 6c, a reception unit 6d, and a second transmission unit 6e. The detection unit 6 a detects congestion of the S-CSCF (A) 61. When the detection unit 6a detects the congestion of the S-CSCF (A) 61, the specifying unit 6b waits for the mobile communication in standby among the plurality of mobile communication terminals 2a and the like controlled by the S-CSCF (A) 61. Identify the terminal. The first transmission unit 6c sends a transfer request to the effect that the communication control for the mobile communication terminal specified by the specifying unit 6b is performed instead of the S-CSCF (A) 61 in which congestion is detected. To other S-CSCFs (S-CSCF (B) 62).

  In addition, the communication system 1 according to the embodiment includes the S-CSCF (A) 61 and the mobile communication terminal 2b that the S-CSCF (A) 61 performs communication control (and further location registration) from the S-CSCF (A) 61. And an S-CSCF (B) 62 that receives a transfer request for transfer. The S-CSCF (B) 62 (the same applies to the S-CSCF (A) 61) includes a reception unit 6d and a second transmission unit 6e. The receiving unit 6d receives the transfer request. When the transfer request is received by the receiving unit 6d, the second transmitting unit 6e transmits the mobile communication terminal 2a such as the mobile communication terminal 2a, the HSS 8 and the mobile communication terminal to the S-CSCF (A) 61 and the S-CSCF. (B) A communication control server that performs communication control of a mobile communication terminal that is a transfer target in the transfer request received by the receiving unit 6d with respect to the P-CSCF 4 that is communicatively connected to 62 is an S-CSCF (A) 61. A change request for changing to S-CSCF (B) 62 is transmitted.

  The S-CSCF (A) 61 determines whether or not the own device is congested. If the own device is congested, the mobile communication terminal that is waiting among the mobile communication terminals that control the communication of the own device is changed to another S-CSCF (A) 61. -Transfer to CSCF. Thereby, since the congestion state of the S-CSCF (A) 61 is avoided, it is possible to avoid the occurrence of a communication failure due to the concentration of the processing load of a specific S-CSCF.

  The S-CSCF (A) 61 according to the embodiment may further include a determination unit 6f and a notification unit 6g. Whether the determination unit 6f is congested with other communication control servers (such as S-CSCF (B) 62 and S-CSCF (C) 63) that can be connected to the mobile communication terminals 2a and 2b via the P-CSCF 4. Determine whether or not. In this case, the P-CSCF 4 connects the mobile communication terminal (mobile communication terminal 2b) specified by the specifying unit 6b to the S-CSCF (A) 61. Further, the notification unit 6g is specified by the specifying unit 6b when there is one communication control server (S-CSCF (B) 62) that is determined not to be congested by the determination unit 6f, and the S-CSCF (A) The P-CSCF 4 and the HSS 8 that manages the mobile communication terminal 2b are notified that the mobile communication terminal 2b whose location registration and communication control have been performed by the 61 is transferred from the S-CSCF (A) 61 (transfer notification). . In this case, the first transmission unit 6c of the S-CSCF (A) 61 transmits a transfer request for the mobile communication terminal 2b to the one communication control server (S-CSCF (B) 62) described above.

  In addition, the communication system 1 according to the embodiment includes the S-CSCF (A) 61 including the determination unit 6f and the notification unit 6g described above, and other determinations that are determined not to be congested by the S-CSCF (A) 61. S-CSCF (B) 62, S-CSCF (A) 61 and S-CSCF (B) 62, and P-CSCF 4 for communication connection between mobile communication terminals 2a and 2b, and mobile communication terminals 2a and 2b You may provide HSS8 to manage. In this case, the receiving unit 6d (first receiving means) of the S-CSCF (B) 62 transmits the mobile communication terminal 2b that has been subjected to communication control (and location registration) by the S-CSCF (A) 61 to the S-CSCF (B) 62. (A) The transfer request for transfer from 61 is received, and the second transmitter 6e moves to the P-CSCF 4 and the HSS 8 when the transfer request of the mobile communication terminal 2b is received by the receiver 6d. A change request for changing the communication control server that performs communication control (and further location registration) of the communication terminal 2b from the S-CSCF (A) 61 to the determined S-CSCF (B) 62 is transmitted. And about P-CSCF4 and HSS8, each of the receiving part 41 and the receiving part 81 receives the transfer notification which shows transfer of the mobile communication terminal 2b, and the change request of the S-CSCF address which concerns on this transfer notification, When each of the receiving unit 41 and the stopping unit 83 receives the transfer notification of the mobile communication terminal 2b, each of the stopping unit 43 and the stopping unit 83 receives a change request from each of the receiving unit 41 and the stopping unit 83. The processing for the mobile communication terminal 2b specified by the specifying unit 6b is stopped.

It is a figure which shows the structure of the communication system which concerns on embodiment. It is a figure which shows the structure of P-CSCF and HSS which concern on embodiment. It is a figure which shows the structure of P-CSCF and HSS which concern on embodiment. It is a figure which illustrates subscriber information which P-CSCF and HSS concerning an embodiment have. It is a figure which shows the structure of S-CSCF which concerns on embodiment. It is a figure which shows the structure of S-CSCF which concerns on embodiment. It is a figure which illustrates the subscriber information which S-CSCF which concerns on embodiment has. It is a sequence for demonstrating operation | movement of the communication system which concerns on embodiment. It is a figure which shows the structure of P-CSCF and HSS which concern on a modification. It is a figure which shows the structure of S-CSCF which concerns on a modification. It is a figure which illustrates transfer destination management information which S-CSCF which concerns on a modification has. It is a sequence for demonstrating operation | movement of the communication system which concerns on a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Communication system 12, 14 ... Subscriber information, 12a ... Telephone number information, 12b ... S-CSCF address information, 14a ... Telephone number information, 14b ... Call status information, 14c ... Last call time information, 16 ... Transfer destination Management information, 16a ... S-CSCF address information, 16b ... Status information, 2a, 2b ... Mobile communication terminal, 4 ... P-CSCF, 4a, 8a, 61a ... CPU, 4b, 8b, 61b ... RAM, 4c, 8c, 61c ... ROM, 4d, 8d, 61d ... input device, 4e, 8e, 61e ... output device, 4f, 8f, 61f ... communication device, 4g, 8g, 61g ... recording device, 4h, 8h, 61h ... bus, 41, 81 ... receiving unit, 42, 82 ... changing unit, 43, 83 ... stopping unit, 6a ... detecting unit, 6b ... specifying unit, 6c ... first transmitting unit, 6d ... receiving unit, 6e ... second transmitting unit, 6f ... Judgment part 6 g ... notification unit, 61 ... S-CSCF (A), 62 ... S-CSCF (B), 8 ... HSS

Claims (2)

A communication control server that controls communication of a plurality of mobile communication terminals,
Detecting means for detecting congestion of the communication control server;
When the detection unit detects congestion of the communication control server, a specifying unit for specifying a waiting mobile communication terminal among the plurality of mobile communication terminals controlled by the communication control server;
A transfer request for performing communication control for the mobile communication terminal specified by the specifying means instead of the communication control server for which congestion is detected is transmitted to a communication control server other than the communication control server. A transmission means ;
Determining whether or not another communication control server that can be connected to the mobile communication terminal via the communication connection server that connects the mobile communication terminal specified by the specifying means to the communication control server is congested Means,
Communication management for managing the mobile communication terminal to transfer the communication control for the mobile communication terminal specified by the specifying means when there is one communication control server determined not to be congested by the determining means A notification means for notifying the server and the communication connection server ;
It said first transmission means that sends the transfer request to the first communication control server, a communication control server characterized in that. The communication control server according to claim 1 , another determined communication control server determined not to be congested by the communication control server, and a communication connection server for communication connection between the two communication control servers and the mobile communication terminal And a communication management server that manages the mobile communication terminal,
The determined communication control server is:
First receiving means for receiving a transfer request for transferring the mobile communication terminal controlled by the communication control server from the communication control server;
When the transfer request is received by the first receiving means, the communication control server for controlling communication of the mobile communication terminal is changed to the determined communication control server for the communication connection server and the communication management server. A second transmission means for transmitting a change request to
Each of the communication connection server and the communication management server is:
Second receiving means for receiving a transfer notification indicating transfer of the mobile communication terminal;
Third receiving means for receiving the change request;
And a stop unit that stops processing for the mobile communication terminal until the third receiving unit receives the change request when the second receiving unit receives the transfer notification. system.

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