JP2011041192A - Session control apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a processing load by preventing an application server from performing unnecessary signal transfer processings during session control and to improve the throughput of a network. <P>SOLUTION: A subscriber information storage section of S-CSCF (2-B) stores connection conditions for application servers ASV1, ASV2, in advance. When the S-CSCF (2-B) controls a session between subscriber terminals UE-A and UE-B, on the basis of information corresponding to subscribers stored in the subscriber information storage section of the S-CSCF (2-B), it is then determined whether transmission/reception of a session control signal is required for the application servers ASV1; ASV2 and only when it is determined that the transmission/reception is required as a result of the determination, is the session control signal transmitted/received with the application servers ASV1, ASV2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a session control apparatus and method for performing session control between terminals in an IMS (IP Multimedia Subsystem).

  A next generation network (NGN) discussed in ITU-T and the like assumes a network architecture in which services are provided via an IP (Internet Protocol) network. NGN has decided to adopt IMS formulated by 3GPP (3rd Generation Partnership Project), which is a standard organization for third-generation mobile communication networks, and provides network services using this IMS. The IMS is a subsystem that performs service execution control, session control between terminals, registration processing, charging processing, and the like by using SIP (Session Initiation Protocol) as a protocol. In IMS, it is possible to execute various applications by using an application server (AS) using SIP. By using an application server, IMS can not only establish a multimedia session between two parties, but also realize an extended service. As services realized by using an application server, a CAT (Customized Alerting Tone) service, a hold service, and the like are known (see, for example, Non-Patent Document 1 and Non-Patent Document 2).

  By the way, when a session is established between an originating terminal and a terminating terminal via an application server, a session control server (S-CSCF: Call Session Control Function), for example, as shown in FIG. Starting from the servers ASV1 and ASV2, a session is established by forming two flows between the terminal UE-A that is the source and the terminal UE-B that is the destination.

  FIG. 11 shows an example of route information constructed in the process of establishing the session, that is, a Route Set. When a session is established between the source terminal UE-A and the destination terminal UE-B, the identification information A, B, C of each node interposed between the terminals UE-A and UE-B Route Set is generated by sequentially recording 1, C, and D. This Route Set is notified by a response signal from the destination terminal UE-B to the source terminal UE-A, and subsequently transferred between the source terminal UE-A and the destination terminal UE-B. The control signal is transferred according to the Route Set (see, for example, Non-Patent Document 3 to Non-Patent Document 6).

3GPP TS 24.182 V8.2.0 (2009-06); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; IP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT); Protocol specification (Release 8); Chapter 4 etc., Jun .2009 3GPP TS 24.610 V8.3.0 (2009 03); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Communication HOLD (HOLD) using IP Multimedia (IM) Core Network (CN) subsystem; Protocol specification (Release 8); 4 Chapters, Mar. 2009 3GPP TS 23.228, V8.9.0 (2009-06); 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; IP Multimedia Subsystem (IMS); Stage 2 (Release 8); 4.2.4, 24, Jun. 2009 3GPP TS 24.229, V8.8.0 (2009-06); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ( Release 8); 5.4.3.2, 66, Jun. 2009 3GPP TS 23.218, V8.4.0 (2008-12); 3rd Generation Partnership Project; Technical Specification Group 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; IP Multimedia (IM) session handling; IM call model; Stage 2 (Release 8); 5.2.1-5.2.3, 12-13, Dec. 2008 3GPP TS 29.228, V8.5.0 (2009-03); 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; IP Multimedia (IM) Subsystem Cx and Dx interfaces; Signaling flows and message contents (Release 8); Annex B ( informative): Chapter 2.2, Chapter 2.3, pp. 52-54 Mar.2009

  However, in the conventional session control method described above, the transfer control of the session control signal is performed in a state where the application server is always present over the entire period from the start to the end of the session control process. For this reason, even if it becomes unnecessary to intervene an application server during execution of an actual service, for example, as shown in FIG. 12, the session control signal always passes through the application server ASV1. As a result, there has been a problem that the application server ASV1 has a useless load due to an unnecessary session control signal transmission / reception process.

  Further, for example, as shown in FIG. 13, when the number of application servers ASV1, ASV2, ASV3,... Intervening in the transfer route increases, the data size of the session control signal increases due to the increase in the amount of information in the route set, and the SIP There was also a concern that the increase in the number of hops would cause a decrease in network throughput.

  The present invention has been made paying attention to the above circumstances, and its purpose is to reduce the processing load on the application server so that unnecessary signal transfer processing is not performed in the application server during session control. It is an object of the present invention to provide a session control apparatus and method capable of reducing and improving throughput in a network.

  In order to achieve the above object, one aspect of the present invention is a session control apparatus provided in a network using IMS (IP Multimedia Subsystem) and performing session control between subscriber terminals via an application server. For each service, filter information including extended information indicating transmission / reception conditions of the session control signal to the application server is stored in the filter information storage means. During session control between the subscriber terminals, transmission / reception of session control signals to / from the application server is performed based on the extended information included in the stored filter information corresponding to the service used by the subscriber terminals. The necessity is determined, and the transmission / reception of the session control signal with the application server is controlled based on the result of the determination.

  Therefore, by storing beforehand the extended information indicating the transmission / reception conditions of the session control signal for the application server in the filter information, the extended information included in the stored filter information at the time of session control between subscriber terminals. Whether or not it is necessary to transmit / receive a session control signal to / from the application server is determined based on the above, and a session control signal is transmitted / received to / from the application server based on the determination result. For this reason, the session control signal is transmitted to and received from the application server only when a preset condition is satisfied. Accordingly, useless session control signals are not transmitted and received in the application server, thereby reducing the processing load on the application server.

Another aspect of the present invention is characterized by comprising the following specific modes.
In the first aspect, when the route information indicating the session control path is constructed in response to the session establishment request transmitted from the originating subscriber terminal, the identification information of the application server is not recorded in the route information. It is something to control.
In this way, the application server identification information is not recorded in the route information constructed at the time of the session establishment request. Therefore, it is possible to conceal the presence of the application server on the session control path from the subscriber terminal. In addition, the information size of the route information can be reduced by not recording the identification information of the application server, so that the session control signal can be obtained even when the subscriber terminal uses a number of application server services. The data size can be reduced.

In the second aspect, information specifying any one of “always”, “before session establishment”, and “after session establishment” is stored as the extension information of the filter information. When performing session control, according to the extended information included in the stored filter information, when the extended information is “always”, the session control signal is always transmitted and received with the application server, When the above extended information is “before session establishment” and “after session establishment”, control is performed so that session control signals are transmitted / received to / from the application server only during the period before session establishment and after session establishment. is there.
In this way, three types of transmission / reception permission periods of “always”, “before session establishment”, and “after session establishment” can be designated as the transmission / reception conditions for the session control signal. Transmission and reception of session control signals with the server can be controlled.

  That is, according to one aspect of the present invention, it is possible to reduce the processing load on the application server and improve the throughput in the network by preventing unnecessary signal transfer processing from being performed on the application server during session control. A session control apparatus and method can be provided.

1 is a schematic configuration diagram of an IMS network system having a session control function (S-CSCF) according to an embodiment of the present invention. The block diagram which shows the structure of the session control function (S-CSCF) concerning one Embodiment of this invention. The figure which shows an example of a structure of initial Filter Criteria which the session control function (S-CSCF) shown in FIG. 2 preserve | saves as subscriber information. The figure which shows the sequence at the time of IMS CAT transmission in the system shown in FIG. The figure which shows the prior art example of the sequence at the time of IMS CAT transmission. The figure which shows the sequence at the time of the pending | holding service execution in the system shown in FIG. The figure which shows the prior art example of the sequence at the time of pending | holding service execution. The figure which shows the flow which comprises the session produced | generated in the system shown in FIG. The figure which shows the construction operation | movement of Route set in the system shown in FIG. The figure which shows the flow which comprises the session produced | generated in the conventional system. The figure which shows construction | assembly operation | movement of Route set in a conventional system. The figure for demonstrating the subject of a conventional system. The figure for demonstrating the subject of a conventional system.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a network system having a session control function according to an embodiment of the present invention. This network system is composed of a network based on IMS (IP Multimedia Subsystem) managed by a telecommunications carrier, and uses SIP (Session Initiation Protocol) as a communication protocol.

The IMS network NW includes a plurality of SIP servers SSV-A and SSV-B, a plurality of application servers (AS) ASV1 and ASV2, and a subscriber information database (HSS: Home Subscriber Server) DB.
Among these, SIP servers SSV-A and SSV-B are respectively P-CSCF (Proxy-Call Session Control Function) 1-A, 1-B and S-CSCF (Serving-Call Session Control Function) 2-A, 2 -B and I-CSCF (Interrogating-Call Session Control Function) (not shown). The P-CSCF 1-A and 1-B function as proxy servers. The P-CSCF 1-A and 1-B include subscriber terminals UE such as mobile phones, PDAs (Personal Digital Assistants), and personal computers. -A and UE-B are connected.

  The S-CSCFs 2-A and 2-B function as session control servers. Based on the subscriber information stored in the subscriber information database DB, the subscriber terminals UE-A and UE-B and the application server Session control processing such as session establishment and release by SIP for ASV1 and ASV2 is performed.

  The application servers ASV1 and ASV2 provide various services to subscribers and are connected to the S-CSCFs 2-A and 2-B. As an additional service, for example, a CAT (Customized Alerting Tone) service that provides a special ringing tone such as music data instead of RBT (Ring Back Tone) to a calling subscriber terminal, or a subscriber terminal that performs a hold operation For example, there is a hold service that provides a hold sound, an answering machine service that records call voice data transmitted from a subscriber terminal, and the like.

By the way, the S-CSCF2-A and 2-B are configured as follows. FIG. 2 is a block diagram showing the functional configuration.
That is, the S-CSCFs 2-A and 2-B include a control unit 21, a storage unit 22, and a SIP transmission / reception unit 23. First of all, the SIP transmission / reception unit 23 transmits / receives a SIP signal to / from the P-CSCF 1 -A, 1 -B, the application servers ASV 1 and ASV 2, and the subscriber information database DB under the control of the control unit 21. .

  The storage unit 22 is provided with a subscriber information storage unit 221. The subscriber information storage unit 221 stores initial Filter Criteria 40 as one piece of subscriber information. This initial Filter Criteria 40 is downloaded from the subscriber information database (HSS) DB at the time of subscriber registration.

  The initial Filter Criteria 40 includes a Trigger Point 41 and Application Server management information 42 as shown in FIG. The Trigger Point 41 has a plurality of Service Point Triggers 411 to 44n. Each Service Point Trigger 411-44n determines which service condition the condition inserted in the header or the like of the received session control signal matches. Request-URI 51, SIP Method 52, SIP Header 53, Session Case 54 and Session Description 55 are included. Request-URI 51 represents the destination of the SIP signal. SIP Method 52 represents a SIP method that is a target of INVITE, OPTIONS, SUBSCRIBE, or the like. The SIP Header 53 is used to determine the presence or absence of a SIP Header to be searched or the presence or absence of a partial / perfect match condition. Session Case 54 represents a condition such as a session direction. As this condition, there are five patterns such as a signal addressed to the caller (in-service / out-of-service area), a signal addressed to the call-in party (in-service / out-of-service area), and a caller after the transfer service. Session Description 55 is used to determine a condition that is partial / completely coincident with the content described in the body (body part) of the session control signal.

  Each Service Point Trigger 411 to 41n newly stores AS handling case within session 56 as control information necessary to realize the present invention. AS handling case within session 56 specifies connection conditions for application servers ASV1 and ASV2, and three types of transmission / reception permission are set as "always", "only before session establishment", and "only after session establishment" as connection conditions. Specify one of the periods.

  On the other hand, the Application Server management information 42 stores information necessary for connecting to the application servers ASV1 and ASV2, and is a condition that matches the condition of the received session control signal among the above Service Point Triggers 411 to 41n. Read when Service Point Trigger including is found. In the Application Server management information 42, a SIP URI 61, a default handling 62, and service information 63 are stored. The SIP URI 61 represents a destination of a connection destination target application server. The default handling 62 defines what operation is performed when the session control signal becomes unreachable to the application server. Service Information 63 represents a notification column of contents notified from the application server to the session control server SSV1.

Further, AS handling case within session 64 is also newly stored in the Application Server management information 42 as in the case of the Service Point Trigger 41. The AS handling case within session 64 has the same contents as the AS handling case within session 56 stored in the Service Point Trigger 41 and is used as a spare for the AS handling case within session 56.
The basic configuration and functions of the initial filter criteria 40 are described in detail in Annex B.2.2 and 2.3 of Non-Patent Document 4.

  The control unit 10 includes a route information construction unit 211, an AS transmission / reception necessity determination unit 212, and a signal transmission / reception control unit 213 as control functions according to the present invention. All of these control functions are realized by causing a CPU (Central Processing Unit) to execute a control program.

  The route information construction unit 211, when receiving a session establishment request transmitted from a source subscriber terminal, indicates route information indicating a signal transfer path from the source subscriber terminal to the destination subscriber terminal ( In the Route set), the identification information of the application servers ASV1 and ASV2 is not recorded, but only the identification information of the own session control server SSV1 is recorded. That is, a process for concealing the application servers ASV1 and ASV2 from the route information is performed.

  The AS transmission / reception necessity determination unit 212 refers to the initial Filter Criteria 40 stored in the subscriber information storage unit 221 of the storage unit 22 when the session control signal transmitted from the subscriber terminal is received, It is determined whether or not the session control process corresponds to the connection condition described in AS handling case within session 56, and the necessity of transmission / reception of the session control signal to the application servers ASV1 and ASV2 is determined based on the determination result To do.

  The signal transmission / reception control unit 213 communicates with the application servers ASV1 and ASV2 only when transmission / reception is determined to be necessary based on the determination result of whether transmission / reception of the session control signal is required by the AS transmission / reception necessity determination unit 212. The session control signal is transmitted / received to / from the application server ASV1 using the flow formed in the above. The flow formed between the application servers ASV1 and ASV2 is independent from the flow formed between the calling subscriber terminal and the called subscriber terminal.

Next, the operation of the session control server (S-CSCF) 2-A, 2-B configured as described above will be described using two types of services as examples.
(1) When receiving IMS CAT service
Here, a case where the subscriber terminal UE-A is a source, the subscriber terminal UE-B is a destination, and the source subscriber terminal UE-A uses a CAT service will be described as an example. The CAT service is provided by the application server ASV1. FIG. 4 is a diagram showing the control sequence.

  First, when the originating subscriber terminal UE-A transmits a session establishment request INVITE (Offer A1), this INVITE (Offer A1) is received by the P-CSCF1-A that accommodates the subscriber terminal UE-A. After that, the data is transferred to the S-CSCF2-A, and transferred from the S-CSCF2-A to the S-CSCF2-B that accommodates the destination subscriber terminal UE-B.

  Upon receiving the session establishment request INVITE (Offer A1), the receiving S-CSCF2-B determines whether transmission / reception of the session control signal to / from the application server is performed by the AS transmission / reception necessity determination unit 212 as follows. judge. That is, first, based on the received INVITE (Offer A1), the Service Point Trigger in which the conditions corresponding to the calling subscriber are stored from the initial Filter Criteria 40 stored in the subscriber information storage unit 221. Search for. Next, it is determined whether or not the current session control process corresponds to the connection condition described in AS handling case within session 56 of the searched Service Point Trigger. If the current session control process satisfies the connection condition as a result of this determination, it is determined that transmission / reception of a session control signal to the application server is necessary.

  For example, if “only before session establishment” is described as a connection condition in the AS handling case within session 56, the current session control process is in a state before the session establishment, and thus corresponds to the connection condition. Therefore, the AS transmission / reception necessity determination unit 212 determines that transmission / reception of a session control signal to the application server ASV1 is necessary.

  When the AS transmission / reception necessity determining unit 212 determines that transmission / reception is necessary, the application server management information 42 is read by the signal transmission / reception control unit 213, and the application server ASV 1 is based on the information described in the management information 42. Session establishment request INVITE (Offer A1) is transmitted / received to / from. At this time, the transmission / reception of INVITE (Offer A1) to / from the application server ASV1 is performed between the originating subscriber terminal and the terminating subscriber terminal as shown in FIG. Is performed by an independent flow.

  Upon receiving the INVITE (Offer A1), the application server ASV1 gives INVITE (Offer A1) to the MRF as the sound source. The MRF secures a CAT resource according to the above INVITE (Offer A1), and returns 200 OK (CAT-answer) to the application server ASV1.

  When INVITE (Offer A1) is returned from the application server ASV1, the S-CSCF2-B transmits INVITE (Offer A1) to the destination subscriber terminal UE-B. This INVITE (Offer A1) is transferred to the called subscriber terminal UE-B via the P-CSCF1-B. When receiving the INVITE (Offer A1), the destination subscriber terminal UE-B returns 183 (Answer B1). When 183 (Answer B1) is returned, the S-CSCF2-B causes the application 183 (Answer B1) to be transferred to the application by a flow different from the flow formed with the destination subscriber terminal UE-B. Transfer to server ASV1. When the PRACK is returned from the application server ASV1, the PRACK is transferred to the destination subscriber terminal UE-B. On the other hand, when the response signal 200OK (PRA) is returned from the destination subscriber terminal UE-B, the S-CSCF2-B transfers the 200OK (PRA) to the application server ASV1. When the application server ASV1 receives the response signal 200OK (PRA), the MRF reads and decodes the compressed music data for CAT from the storage medium, and starts transmitting the decoded music data.

On the other hand, when INVITE (Offer A1) is received from the originating subscriber terminal UE-A, the application server ASV1 returns 183 (session: CAT-answer). This 183 (session: CAT-answer) is transferred to the originating subscriber terminal UE-A via the originating S-CSCF2-A and P-CSCF1-A. When receiving the above 183 (session: CAT-answer), the originating subscriber terminal UE-A returns a PRACK. This PRACK is transferred to the receiving side S-CSCF2-B via the transmitting side P-CSCF1-A and S-CSCF2-A, and further transferred to the application server ASV1. On the other hand, when the application server ASV1 returns a response signal 200OK (PRA), the 200OK (PRA) is transferred from the S-CSCF2-B on the receiving side to the subscriber terminal UE-A that is the transmission source.
Thus, the music data for CAT transmitted from the MRF is transferred to the originating subscriber terminal UE-A, and is output instead of the RBT at the originating subscriber terminal UE-A. Therefore, it is possible to confirm from the music that the calling user is calling.

  In this state, when the user answers the incoming call at the destination subscriber terminal UE-B, 200 OK (INV) (no SDP) is transmitted from the destination subscriber terminal UE-B. When the S-CSCF2-B receives the 200OK (INV) (no SDP), the S-CSCF2-B transfers the 200 OK (INV) (no SDP) to the application server ASV1. Upon receiving this 200OK (INV) (no SDP), the application server ASV1 transmits an end signal BYE to the MRF. Upon receiving this end signal BYE, the MRF stops the transmission of the CAT audio data, and returns a response signal 200OK (BYE) to the application server ASV1.

When receiving 200OK (INV) (no SDP), the application server ASV1 transmits UPDATE (Offer B1) to the originating subscriber terminal UE-A. On the other hand, the originating subscriber terminal UE-A returns 200 OK (UDP) (Answer A2). This 200 OK (UDP) (Answer A2) is transferred to the incoming S-CSCF2-B via the outgoing P-CSCF1-A and S-CSCF2-A, and further transferred to the application server ASV1. On the other hand, when the application server ASV1 returns a response signal 200OK (INV) (no SDP), the 200 OK (INV) (no SDP) is transmitted from the S-CSCF2-B on the receiving side to the subscriber terminal UE- Forwarded to A.
Thus, a session is established between the originating subscriber terminal UE-A and the called subscriber terminal UE-B, and thereafter, media data for a call is established between the two terminals as shown at 6a in FIG. It becomes a transfer state.

  When the media data is transferred, the originating subscriber terminal UE-A first returns an ACK to the 200OK (INV) (no SDP). This ACK is transferred to S-CSCF2-B on the receiving side via P-CSCF1-A and S-CSCF2-A on the calling side. When the ACK is received, the S-CSCF2-B on the receiving side stores the condition corresponding to the calling subscriber from the initial filter criteria 40 stored in the subscriber information storage unit 221 by the AS transmission / reception necessity determination unit 212. The searched Service Point Trigger is searched, and it is determined whether or not the current session control process corresponds to the connection condition described in AS handling case within session 56 of the searched Service Point Trigger.

For example, the current session control process is after session establishment, and the connection condition described in AS handling case within session 56 is “before session establishment”. For this reason, the AS transmission / reception necessity determination unit 212 determines that the current session control process does not correspond to the connection condition, and determines that transmission / reception of the session control signal to the application server ASV1 is unnecessary.
When the AS transmission / reception necessity determination unit 212 determines that transmission / reception is not necessary, the signal transmission / reception control unit 213 omits transmission of the ACK to the application server ASV1, and transmits the ACK to the destination subscriber terminal UE-B. Forward.

After that, every time a session control signal is transmitted from the subscriber terminals UE-A and UE-B, the AS transmission / reception necessity determination unit 212 determines that the current session control process is performed by the AS handling in the S-CSCF2-B on the called side. It is determined whether the connection condition described in case within session 56 is satisfied. Since the current session control process is after the session is established and does not correspond to the connection condition described before AS handling case within session 56 (before the session is established), the signal transmission / reception control unit 213 performs the above-described communication with the application server ASV1. Transmission / reception of session control signals is omitted.
Therefore, after a session is established between the subscriber terminals UE-A and UE-B, unnecessary session control signals are not transmitted and received between the S-CSCF2-B and the application server ASV1. This reduces the processing load on the application server ASV1.

  FIG. 5 shows a sequence when the above-described determination of whether or not AS transmission / reception is necessary is not performed. As shown in FIG. 8a, the session control signal ACK is unconditional between the S-CSCF2-B and the application server ASV1 even after the session is established between the subscriber terminals UE-A and UE-B. Sent and received. For this reason, the application server ASV1 is forced to perform a substantially unnecessary session control signal transmission / reception process, and the processing load increases accordingly.

(2) When receiving a hold service
Here, a case will be described as an example where a hold service is executed in response to an operation of a destination subscriber terminal UE-B in a state where a session is established between the subscriber terminals UE-A and UE-B. The hold service is provided by the application server ASV2. FIG. 6 is a diagram showing the control sequence.

  First, when the originating subscriber terminal UE-A transmits a session establishment request INVITE (Offer A1), this INVITE (Offer A1) is received by the P-CSCF1-A that accommodates the subscriber terminal UE-A. After that, the data is transferred to the S-CSCF2-A, and transferred from the S-CSCF2-A to the S-CSCF2-B that accommodates the destination subscriber terminal UE-B.

  Upon receiving the session establishment request INVITE (Offer A1), the receiving S-CSCF2-B determines whether transmission / reception of the session control signal to / from the application server is performed by the AS transmission / reception necessity determination unit 212 as follows. judge. That is, first, based on the received INVITE (Offer A1), the Service Point Trigger in which the conditions corresponding to the calling subscriber are stored from the initial Filter Criteria 40 stored in the subscriber information storage unit 221. Search for. Next, it is determined whether or not the current session control process corresponds to the connection condition described in AS handling case within session 56 of the searched Service Point Trigger. As a result of this determination, if the current session control process does not satisfy the connection condition, it is determined that transmission / reception of a session control signal to the application server is unnecessary.

  For example, if “only after session establishment” is described as a connection condition in the AS handling case within session 56, the current session control process is the state before the session establishment (7a in FIG. 6). Not applicable. Therefore, the AS transmission / reception necessity determination unit 212 determines that transmission of the INVITE (Offer A1) to the application server ASV2 is unnecessary.

  When the AS transmission / reception necessity determination unit 212 determines that transmission / reception is not required, the signal transmission / reception control unit 213 omits transmission of the session establishment request INVITE (Offer A1) to the application server ASV2, and the INVITE (Offer A1 ) To the destination subscriber terminal UE-B. This INVITE (Offer A1) is transferred to the called subscriber terminal UE-B via the called-side P-CSCF1-B. Upon receiving INVITE (Offer A1), the destination subscriber terminal UE-B returns a response signal 183 (Answer B1).

  Even when the response signal 183 (Answer B1) is received, the S-CSCF2-B uses the AS transmission / reception necessity determination unit 212 to determine whether or not it is necessary to transmit / receive a session control signal to / from the application server ASV2. Also in this case, since the current session control process is the state before session establishment (7a in FIG. 6), it does not correspond to the connection condition described in AS handling case within session 56, that is, “only after session establishment”. Therefore, the AS transmission / reception necessity determination unit 212 determines that transmission of the response signal 183 (Answer B1) to the application server ASV2 is unnecessary.

  When the AS transmission / reception necessity determination unit 212 determines that transmission / reception is unnecessary, the signal transmission / reception control unit 213 omits the transmission of the response signal 183 (Answer B1) to the application server ASV2, and the 183 (Answer B1) To the originating subscriber terminal UE-A. The 183 (Answer B1) is transferred to the originating subscriber terminal UE-A via the originating S-CSCF2-A and P-CSCF1-A.

Thereafter, similarly, whenever a session control signal such as PRACK, 200OK (PRA), 200OK (INV), ACK, etc. is transmitted from the subscriber terminals UE-A and UE-B, the AS in the S-CSCF2-B on the receiving side The transmission / reception necessity determination unit 212 determines whether or not the current session control process corresponds to the connection condition described in AS handling case within session 56. Since the current session control process is before session establishment and does not correspond to the connection condition (after session establishment) described in AS handling case within session 56, the signal transmission / reception control unit 213 performs the above-described communication with the application server ASV2. Transmission / reception of session control signals is omitted.
Therefore, in a state before the session is established between the subscriber terminals UE-A and UE-B, unnecessary session control signals are not transmitted and received between the S-CSCF2-B and the application server ASV2. As a result, the processing load on the application server ASV2 is reduced.

On the other hand, in a state after the session is established between the subscriber terminals UE-A and UE-B, an AS transmission / reception necessity determination process and a session control signal transmission / reception process based on the determination result are performed as follows.
That is, when a hold operation is performed in the subscriber terminal UE-B, INVITE (sendonly) is transmitted from the subscriber terminal UE-B. When receiving this INVITE (sendonly), the S-CSCF2-B on the receiving side determines whether transmission / reception of a session control signal to / from the application server ASV2 is performed by the AS transmission / reception necessity determination unit 212.

  That is, first, based on the received INVITE (sendonly), the service point trigger that stores the conditions corresponding to the calling subscriber is searched from the initial filter criteria 40 stored in the subscriber information storage unit 221. To do. Next, it is determined whether or not the current session control process corresponds to the connection condition described in AS handling case within session 56 of the searched Service Point Trigger. If the current session control process satisfies the connection condition as a result of this determination, it is determined that transmission / reception of a session control signal to the application server is necessary.

  For example, since the AS handling case within session 56 now describes “after session establishment” as the connection condition, the current session control process is in the state after the session establishment, and therefore corresponds to the connection condition. Therefore, the AS transmission / reception necessity determination unit 212 determines that transmission / reception of the session control signal to / from the application server ASV2 is necessary.

  When the AS transmission / reception necessity determination unit 212 determines that transmission / reception is necessary, the application server management information 42 is read by the signal transmission / reception control unit 213, and the application server ASV 2 is based on the information described in the management information 42. The above INVITE (sendonly) is transmitted / received to / from. At this time, transmission / reception of INVITE (sendonly) to / from the application server ASV2 is a flow formed between the subscriber terminal UE-A and the subscriber terminal UE-B as shown in FIG. This is done by an independent flow.

  Upon receiving the INVITE (sendonly), the application server ASV2 transmits the INVITE (sendonly) to the subscriber terminal UE-A. This INVITE (send only) is transferred to the subscriber terminal UE-A via the S-CSCF2-A and the P-CSCF1-A. When receiving the INVITE (sendonly), the subscriber terminal UE-A returns a response signal 200OK (recvonly). This response signal 200OK (recvonly) is transferred to S-CSCF2-B via P-CSCF1-A and S-CSCF2-A.

  When this 200OK (recvonly) is received, the S-CSCF2-B determines whether the 200OK (recvonly) transmission / reception with respect to the application server ASV2 is necessary by the AS transmission / reception necessity determination unit 212. As a result of this determination, the session is now established and AS handling case within session 56 describes “after session establishment” as the connection condition, so the 200 OK (recvonly) transmission / reception with respect to the application server ASV2 is necessary. Judge. When it is determined that transmission / reception is necessary, the signal transmission / reception control unit 213 transmits the 200OK (recvonly) to the application server ASV2.

When the application server ASV2 receives the 200OK (recvonly), the application server ASV2 instructs the MRF, which is a holding sound source, to transmit a holding sound. As a result, the MRF reads and decodes the compressed hold sound data from the storage medium, and transmits the decoded hold sound data. The music on hold data is transferred from the application server ASV2 to the subscriber terminal UE-A via the S-CSCF2-B, S-CSCF2-A, and P-CSCF1-A. Thus, it can be confirmed that the user of the subscriber terminal UE-A is on hold.
When the hold sound transmission instruction to the MRF is completed, the application server ASV2 returns the 200OK (recvonly) to the S-CSCF2-B. The S-CSCF2-B transmits the 200OK (recvonly) to the subscriber terminal UE-B that has performed the hold operation.

  FIG. 7 shows a sequence in the case where the determination of necessity of AS transmission / reception is not performed when the provision of the above-described hold service is received. As shown in FIG. 9a, there is no session control signal between the S-CSCF2-B and the application server ASV2 in the state before the session is established between the subscriber terminals UE-A and UE-B. Sent and received on condition. For this reason, the application server ASV1 is forced to perform a substantially unnecessary session control signal transmission / reception process, and the processing load increases accordingly.

(3) Route Information Construction Process In the process of transferring the session establishment request described in (1) and (2) above, the S-CSCF2-B performs the route information construction process as follows. FIG. 9 is a diagram illustrating a route information construction process in a session control path from a source subscriber terminal UE-A to a destination subscriber terminal UE-B.

  When the originating subscriber terminal UE-A transmits a session establishment request INVITE (Offer A1), each node located on the transfer path sequentially records its own node identification information in the route information. For example, the P-CSCF1-A records its own identification information (A) in the route information (Route set), and then the S-CSCF2-A additionally records its own identification information (B) in the route information.

On the other hand, when the S-CSCF2-B receives the session establishment request INVITE (Offer A1), the application server ASV1 or ASV2 is included in the session control path under the control of the route information construction unit 211. In addition, the identification information (1) and (2) of the application servers ASV1 and ASV2 is not recorded in the route information, but only its own identification information (C) is additionally recorded in the route information. Then, this route information is transferred to P-CSCF1-B together with INVITE (Offer A1). When receiving the INVITE (Offer A1), the P-CSCF1-B additionally records its identification information (D) in the route information and then transfers it to the destination subscriber terminal UE-B. When the destination subscriber terminal UE-B receives the route information together with the INVITE (Offer A1), the destination subscriber terminal UE-B stores the route information as the constructed route information, and also sends the subscriber terminal UE-A as a response signal. Return to The originating subscriber terminal UE-A stores the constructed route information received together with the response signal, and thereafter transmits a session control signal using this route information.
Thus, the identification information of the application servers ASV1 and ASV2 is hidden from the route information.

  As described above, in this embodiment, a storage area for AS handling case within session 56 is provided in initial filter Criteria 40, which is one of subscriber information, and connection conditions for application servers ASV1 and ASV2 are set in AS handling case within session 56. I remember it. Then, when the S-CSCF2-B controls the session between the subscriber terminals UE-A and UE-B, based on the AS handling case within session 56 of the initial Filter Criteria 40 corresponding to the subscriber, It is determined whether or not it is necessary to transmit / receive a session control signal to / from the servers ASV1 and ASV2, and a session control signal is transmitted / received to / from the application servers ASV1 and ASV2 only when it is determined that transmission / reception is necessary as a result of this determination. Yes.

  Therefore, the session control signal is transmitted / received between the S-CSCF2-B and the application servers ASV1 and ASV2 only when a connection condition set in advance as AS handling case within session 56 is satisfied. Therefore, useless session control signal transmission / reception processing is not performed in the application servers ASV1 and ASV2, thereby reducing the processing load on the application servers ASV1 and ASV2.

  In addition, session control periods such as “always”, “before session establishment”, and “after session establishment” are selectively stored as connection conditions, and application / application only when the current session control process falls within these periods. Session control signals are transmitted and received between the servers ASV1 and ASV2. For this reason, connection conditions can be specified by three types of transmission / reception permission periods of “always”, “before session establishment”, and “after session establishment”, and session control with the application server can be performed under simple conditions. Signal transmission and reception can be controlled.

  Further, when constructing route information (Route set) representing a session control path in response to a session establishment request transmitted from the originating subscriber terminal UE-A, the S-CSCF2-B uses the application servers ASV1, ASV2 Is not recorded in the route information. For this reason, the identification information of the application servers ASV1 and ASV2 can be hidden from the route information. Therefore, the information size of the route information can be reduced, and thus the data size of the session control signal can be reduced even when the subscriber terminal uses a large number of application server services.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, three types of transmission / reception permission periods of “always”, “before session establishment”, and “after session establishment” are set as connection conditions set as AS handling case within session 56. A “session release period” may be added, and connection conditions may be set for each session control signal.

  In the above embodiment, the case where the CAT service and the hold service are provided as examples of the services provided by the application servers ASV1 and ASV2 has been described. However, when other services such as an answering service are provided, The present invention is equally applicable.

  In addition, the configuration of the extended information representing the connection condition with the application server, the configuration of the storage means, the AS transmission / reception necessity determination processing, the procedure of the transmission / reception control processing of the session control signal based on the determination result, and the like are also included in the present invention. Various modifications can be made without departing from the scope of the invention.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  NW: SIP-based IMS network, SSV-A, SSV-B ... SIP server, 1-A, 1-B ... P-CSCF, 2-A, 2-B ... S-CSCF, ASV1, ASV2 ... Application server , UE-A, UE-B ... subscriber terminal, DB ... subscriber information database (HSS), 21 ... control unit, 22 ... storage unit, 23 ... SIP transmission / reception unit, 211 ... route information construction unit, 212 ... AS transmission / reception Necessity determination unit, 213 ... signal transmission / reception control unit, 221 ... subscriber information storage unit, 40 ... Initial Filter Criteria, 41 ... Trigger Point, 411 to 41n ... Service Point Trigger, 42 ... Application Server management information.

Claims (6)

In a session control apparatus that is provided in a network using IMS (IP Multimedia Subsystem) and performs session control between subscriber terminals via an application server,
Filter information storage means for storing filter information including extended information indicating transmission / reception conditions of a session control signal to the application server for each service;
Whether or not to transmit / receive a session control signal to / from the application server based on the extended information included in the stored filter information corresponding to the service used by the subscriber terminal during session control between the subscriber terminals Determining means for determining
A session control apparatus comprising: a transmission / reception control unit that controls transmission / reception of a session control signal to / from the application server based on the determination result.   A means for controlling not to record the identification information of the application server in the route information when constructing route information representing a session control path in response to a session establishment request transmitted from a subscriber terminal of a sender, The session control apparatus according to claim 1, further comprising: The filter information storage means stores information designating any one of “always”, “before session establishment”, “after session establishment” as extended information of the filter information,
The transmission / reception control unit always transmits / receives a session control signal to / from the application server when the extended information is “always” according to the determination result based on the extended information included in the stored filter information. When the extended information is “before session establishment” and “after session establishment”, a session control signal is transmitted / received to / from the application server only during a period before session establishment and after session establishment, respectively. Item 3. The session control device according to Item 1 or 2. In a session control apparatus provided in a network using IMS (IP Multimedia Subsystem), a session control method for performing session control between subscriber terminals via an application server,
Storing filter information including extended information indicating transmission / reception conditions of a session control signal for the application server for each service in a storage medium;
When controlling a session between the subscriber terminals, filter information corresponding to a service used by the subscriber terminals is read from the storage medium, and based on the extended information included in the read filter information Determining whether or not it is necessary to transmit / receive a session control signal to / from the application server, and controlling transmission / reception of a session control signal to / from the application server based on a result of the determination. Session control method to use.   A process of controlling not to record the identification information of the application server in the route information when constructing route information representing a session control path in response to a session establishment request transmitted from a subscriber terminal of a transmission source, The session control method according to claim 4, further comprising: The process of storing the filter information stores, as extended information of the filter information, information that designates “always”, “before session establishment”, “after session establishment”,
In the control process, according to the determination result based on the extension information included in the stored filter information, when the extension information is “always”, the session control signal is always transmitted and received with the application server. When the extended information is “before session establishment” and “after session establishment”, a session control signal is transmitted / received to / from the application server only during a period before session establishment and after session establishment, respectively. Item 6. The session control method according to Item 4 or 5.

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