KR20060113284A - Ip multimedia subsystem for supprting voice service and call setup method thereof - Google Patents

Abstract

An IMS(IP Multimedia Subsystem) for supporting a voice service between different networks and its call setup method are provided to allow providers of services such as the wireless Internet or WCDMA to provide a voice service. A CSCF(Call Session Control Function)(111) processes a call and a session of networks by using the SIP(Session Initiation Protocol). An HSS(Home Subscriber Server)(140) stores an integrated profile of data service and voice service subscribers, and transmits the profile to the CSCF(111). An MGCF(Media Gateway Control Function)(121) allocates resources and performs a signaling processing operation when a call is established between networks. An MGW(Media Gateway)(123) converts traffic between networks under control of the MGCF(121).

Description

IP system supporting voice service between heterogeneous networks and call setup method {IP MULTIMEDIA SUBSYSTEM FOR SUPPRTING VOICE SERVICE AND CALL SETUP METHOD THEREOF}

1 is a diagram illustrating an IMS system capable of providing a voice service in an HN according to an exemplary embodiment of the present invention.

2 is a signal flow diagram illustrating a process of registering in the WiBro network when the HAT 190 is first powered on in the IMS system of the present invention.

3 is a signal flow diagram illustrating a process of calling a subscriber in a 3G network by a HAT in a WiBro network area in the IMS system of the present invention;

4 is a signal flow diagram illustrating a process in which a terminal in a 3G network calls a subscriber in a WiBro network area in an IMS system of the present invention.

5 is a block diagram conceptually illustrating an HSS in the IMS system of FIG.

6 is a block diagram conceptually illustrating an S-CSCF in the IMS system of FIG.

The present invention relates to a heterogeneous mobile communication system, and more particularly, to an IP Multimedia Subsystem (IMS) system supporting voice services between heterogeneous networks and a call processing method thereof.

Recently, the next generation communication system is changing to a ubiquitous environment in which wired and wireless integrated environments are pursued. Among services aiming for ubiquitous environment, IMS is a core technology for providing services such as wired / wireless integration, voice / data integration, and communication / broadcast convergence in broadband integration network.

IMS is a network system that can provide multimedia services such as audio, video, text and chat by interworking heterogeneous networks (eg, cellular, WLAN, WiBro, etc.) using IP-based packet networks. Standards are underway in TS 23,228. An access network (AN) connected to each network is linked to the core network (CN) of IMS.

Such an IMS can interoperate with an IP-based network, so that if a user establishes a session in one network, the user can also receive IP services of an external network. In addition, a user can access a network that is advantageous to the user when he can be connected to multiple networks. For example, users connected to an IMS can not only play a game directly on the network, but also have voice conversations with each other. In addition, when access to multiple networks is possible, users can access relatively low-cost networks or efficient networks depending on the type of IP service.

The IMS supports voice services between IP-based packet networks and circuit switched networks. However, in the case of cellular networks, existing IMS systems have limitations in order to efficiently provide voice services based on MSC (Mobile Switching Center) and WLAN (Session Initiation Protocol) based on WLAN and WiBro.

Accordingly, an object of the present invention is to provide an IMS system and a service method thereof capable of efficiently supporting a voice service between heterogeneous networks.

Another object of the present invention is to provide an IMS system and a service method thereof that can be competitive in wired / wireless integrated services by supporting voice services between heterogeneous networks.

The system of the present invention for achieving the above object is a session initial protocol in an IMS (IP Multimedia Subsystem: IMS) system interworking a network providing an IP packet-based data service and a network providing a circuit-based voice service. Call Session Control Function (CSCF) which handles calls and sessions of the networks using Session Initiation Protocol (SIP), and stores the integrated profile of the data service and voice service subscriber A Home Subscriber Server (HSS) for transmitting the profile to the CSCF at the time of transmission, a Media Gateway Control Function (MGCF) for performing resource allocation and signaling processing when establishing a call between mutual networks; Media GateWay (MGW) for converting traffic between networks under the control of the MGCF Characterized by configured to include a mobile terminal that can receive the service of the network.

The CSCF unit provides a proxy CSCF unit for connecting to a network interworking with an IMS system when establishing a call, a serving CSCF unit for receiving a service from the integrated user profile from the HSS during authentication in the interworking network, and an external IMS system. In case of connection with the service, all the incoming calls serve as a point of contact, and if necessary, the integrated CSCF part that performs the role of a firewall in the IMS system for security.

The internal mobile subscriber identifier (IMSI) of the mobile terminal is included in a field of a registration message of the SIP.

In the method of the present invention for achieving the above object in the registration method in the IMS (IP Multimedia Subsystem: IMS) system interworking a network providing an IP packet-based data service and a network providing a circuit-based voice service, The mobile terminal requests the registration setting to the IMS system through the corresponding network currently using the SIP registration message, the process of registering the location using the integrated subscriber profile when the registration request; If the corresponding network in the network providing the voice service, characterized in that it comprises the step of deleting the location registration in the network.

DETAILED DESCRIPTION Hereinafter, detailed descriptions of preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same components in the drawings represent the same numerals wherever possible. Specific details are set forth in the following description, which is provided to aid a more general understanding of the invention. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The present invention to be described later proposes an IMS system capable of providing a voice service in a heterogeneous network (HN) and a call setup method accordingly. Accordingly, first, the IMS system of the present invention will be described, and then a voice service call setup method in the present system will be described according to embodiments.

1 is a diagram schematically illustrating an IMS system capable of providing a voice service between cellular and WLAN / WiBro heterogeneous networks in an HN according to a preferred embodiment of the present invention.

The IMS system according to the present invention represents a system capable of supporting voice services in the IMS system currently defined in 3GPP. The terms described below will not be described in detail in terms defined in the standard.

Referring to FIG. 1, the IMS system 100 according to the present invention is composed of a core network (CN) 110, and the CN 110 is another external network such as Wibro, WCDMA, or external IMS network. It operates in conjunction with 3G network. However, for convenience of description, only the Wibro network 160, the 3G network 150, and the external IMS 180 are shown. In addition, it is assumed that the mobile terminal is a hybrid AT (HAT) capable of receiving services of the 3G network and the external network.

Referring to FIG. 1, the IMS-CN 110 includes a call session control function (CSCF) 111, a home subscriber server (HSS) 140, and a media gateway controller ( Media Gateway Control Function (MGCF) 121, IMS-MGW (IMS-Media GateWay) 123 is configured. The CSCF 111 performs functions related to call and session processing, and according to its role, a proxy CSCF (P-CSCF) 117, an integration CSCF (I-CSCF) 113, It is divided into a serving CSCF (S-CSCF) 115.

The P-CSCF 117 is a component that performs a gateway function when the HAT 190 first accesses a network to receive an IMS service, and performs a proxy and a user agent (UA) function. The I-CSCF 113 serves as a point of contact for all incoming calls to connect to subscribers in the network. The I-CSCF 113 queries the HSS 140 to be described later to locate the called subscriber and routes the call. In addition, since the I-CSCF 113 serves as a gateway to the external IMS 180, the I-CSCF 113 may also play a role of a firewall that hides a topology in the network for security if necessary.

The S-CSCF 115 performs a register function and various authentication functions necessary for the initial registration of the HAT 190, and directly interworks with application servers to provide various multimedia services and based on triggering information. Route and provide services. In addition, since the IMS system 100 of the present invention is linked with the 3G network 150 providing a voice service, the S-CSCF 115 simultaneously displays the 3G subscriber profile and the IMS subscriber profile in the location registration process of the HAT 190. It stores and provides a service for a voice service to the HAT 190.

The HSS 140 stores not only the location information and data information of the conventional IMS subscriber but also subscriber information of the 3G network 150 for voice service. For example, when the Location Query Message (LQ) is raised to reach a subscriber in the WiBro network 160, the HSS 140 sends a location response message according to the sender's location, that is, the 3G domain or the IMS domain. Response: LR) is identified and responded. The HSS 140 according to the present invention is located between the networks to indicate not only IMS subscriber information but also subscriber information of the 3G network 150, but may be located in the IMS-CN 110. The S-CSCF 115 has a Cx interface, and also has an interface with the MSC 151 of the 3G network 150 to communicate with each other using a diameter protocol. Here, a block diagram illustrating the concept of the HSS 140 and the S-CSCF 115 is shown in FIG. 5.

The media gateway control function (MGCF) 121 controls the IMS-Media GateWay (123). The IMS-Media GateWay (123) controls the IMS-CN 110. ) And traffic on the bearer pass of the 3G network 150. That is, the IMS system processes IP-based data, that is, packet data, but the 3G network 150 processes circuit-based data, thereby converting traffic on a bearer pass.

The HAT 190 should use a mobile identity number (MIN) of the terminal in the SIP URL and include a specific field of the registration message of the SIP in the terminal's internal mobile subscriber identifier (IMSI).

Then, the process of registering in the WiBro network 160 when the HAT 190 is first turned on in the IMS system 100 of the present invention will be described with reference to FIG. 2. Here, the HAT 190 shows the registration process in the WiBro network 160, but the same applies to the WLAN network.

Referring to FIG. 2, first, the HAT 190 transmits a SIP registration message to the P-CSCF 117 when the HAT 190 is powered on in the WiBro network 160 in step 201. At this time, the MIN and ESN of the HAT 190 should be included in the SIP registration message, and the lifetime is set to the same value as the system time at the periodic location registration in the 3G network 150. Upon receiving the SIP registration message, the P-CSCF 117 checks the home domain name of the called terminal in step 203 and transmits it to the I-CSCF 113 of the home network. The I-CSCF 111 then sends a Cx-Query message to the HSS 140 in step 205. The Cx-Query message includes information such as a user ID and the P-CSCF 117. Upon receiving the Cx-Query message, the HSS 140 transmits a Cx-Query response message including the address of the S-CSCF 115 to the I-CSCF 111 in step 207. Then, the I-CSCF 111 transmits a SIP registration message to the corresponding S-CSCF 115 in step 209.

Upon receiving the SIP registration message, the S-CSCF 115 transmits a Cx-Put message to the HSS 140 to inform that the server is in charge of the session of the called terminal in step 211. Herein, the Cx-Put message includes an ID of a called terminal, a name of a corresponding S-CSCF, and the like. After checking the Cx-Put message, the HSS 140 transmits the Cx-Put response message to the S-CSCF 115 in step 213. In step 215, the S-CSCF 115 confirming the Cx-Put response message transmits a Cx-Pull message to the HSS 140 to request a subscriber profile. In step 217, the HSS 140 transmits the IMS subscriber profile and the 2G / 3G subscriber profile to the S-CSCF 115 using the Cx-Pull message. In step 219, the HSS 140 deletes location information registered in the MSC 151 by transmitting a registration cancellation message to the MSC 151. The MSC 151 deleting the location information transmits a location cancellation message acknowledgment message (Registration Cancellation_Ack) to the HSS 140 in step 221. In step 217, the S-CSCF 115 receiving the IMS subscriber profile may transmit registration information to the service control platform based on the filter criterion in step 223. Then, in steps 225 to 229, the response message 200 OK is transmitted from the S-CSCF 115 to the HAT 190 which is the called terminal. Then, the registration process according to the present invention is completed.

Next, a process of calling a subscriber in the 3G network 150 by the HAT 190 in the WiBro network 160 area in the IMS system 100 of the present invention will be described with reference to FIG. 3.

Referring to FIG. 3, when the HAT 190, which is the originating terminal in the WiBro network 160, transmits a SIP INVITE message including the called number in step 301, the S-network of the home network passes through the P-CSCF 117. Is passed to the CSCF 115. Then, the S-CSCF 115 checks the INVITE message received in step 303 and transmits it to the called terminal. At this time, the S-CSCF 115 refers to the 3G profile of the calling terminal to determine whether session session is reasonable. Thereafter, the S-CSCF 115 transmits the INVITE message to the MGCF 121 in step 305. Receiving the INVITE message, the MGCF 121 determines whether channel and media capacity of an external call are available using the MGCP / H.248 MEGACO protocol in step 309.

In step 311, the MGCF 121 determines whether the originating terminal is available for the media flow, and transmits a 183 message, which is a response message, to the S-CSCF 115. At the same time, the MGCF 121 modifies the connection parameters set in steps 309, 313, and 315, and instructs the IMS-MGW 123 to allocate necessary resources for this session. Upon receiving the command, the IMS-MGW 123 informs the MGCF 121 of a resource necessary for a media stream.

On the other hand, as shown in step 317, the HAT 190, which is the originating terminal, informs the MGCF 121 of an UPDATE message indicating that resource allocation has been successfully completed. In step 319, the MGCF 121 receiving the update message transmits an IAM (Initial Address Message) message for voice call connection to the MSC 151 of the 3G network 150 where the called terminal is located. At the same time, the MGCF 121 transmits a 200 OK message indicating that the resource is successfully allocated to the HAT 190 which is the originating terminal in step 321. In addition, the MSC 151 sets a path to the called terminal. However, since the MSC 151 is well known, a description thereof will be omitted. In this case, the MSC 151 transmits an address complete message (ACM) message to the MGCF 121 when the path to the called terminal is established in step 323. In step 325, the MGCF 121 notifies the HAT 190 of the calling terminal by transmitting a 180 ringing signal indicating that a ring signal is ringing to the S-CSCF 115 to which the called terminal belongs. Then, when the MGCF 121 receives an ANM (Answer Message) message indicating that the destination terminal is connected and the voice call setup is completed, the MGCF 121 notifies the corresponding IMS-MGW 123 that the call is connected and instructs traffic path setup. do. When the traffic path is set and the MGCF 121 transmits a 200 OK message to the S-CSCF 115 in step 329, the S-CSCF 115 sends an ACK signal, which is a response message thereto, in step 331. The voice call setup process is completed upon transmission to the MGCF 121.

Next, in contrast to the above embodiment, a call setup process when a terminal in the 3G network 150 requests a voice call to a terminal in the WiBro network 160 area will be described with reference to FIG. 4.

Referring to FIG. 4, first, in this embodiment, since the message used in steps 401 to 407 uses the MAP protocol used in IS-41, a detailed description thereof will be omitted.

When the terminal 190 in the 3G network 150 transmits a call request message to the MSC 151 through a cellular base station (not shown) in step 401, the MSC 151 determines the location of the called terminal in step 403. In order to find out, the location request message is transmitted to the HSS 140, LOCREQ message. The HSS 140 receiving the location request message checks the location of the called terminal. If it is determined that the location of the called terminal is located in the WiBro network 160, the HSS 140 determines the Temporary Local Directory Number (TLDN) of the MGCF 151 in the WiBro network 160 connected to the called terminal in step 405. Is transmitted to the MSC 151. Then, the MSC 151 transmits an IAM message for voice call connection to the MGCF 121 where the called terminal is located in step 407. In step 409, the MGCF 121 receiving the IAM message allocates a trunk and an IP port to the IMS-MGW 123 using the MGCP / H.248 MEGACO protocol. Thereafter, the MGCF 121 transmits the SIP INVITE message to the I-CSCF 117 which is a contact point of the home network of the called terminal in step 411. Upon receiving the SIP INVITE message, the I-CSCF 117 sends a location query (LQ) message to the HSS 140 to inquire the address of the S-CSCF 115 in charge of the session of the called terminal in step 413. If so, the HSS 140 transmits a Location Response (LR) message including the address of the S-CSCF 115 in step 415. Thereafter, the I-CSCF 117 transmits an INVITE message for call connection to the S-CSCF 115 in step 417. Here, the call processing in the lower stage in the S-CSCF 115 is well known and will be omitted.

The S-CSCF 115 checks whether the call setup session setup requested from the originating terminal is reasonable in step 419. In response to receiving the response signal from the called terminal in the WiBro network 160, the S-CSCF 115 uses the SDP message including the media stream capability of the called terminal in step 421 using an I- 1 message. The CSCF 117 transmits the data to the MGCF 121. The MGCF 121 then modifies the Connection Parameter in step 423 and instructs the IMS-MGW 123 to allocate the necessary resources for this session. Thereafter, in step 425, resources necessary for the media stream are allocated. When the resource allocation is completed, the MGCF 121 transmits an UPDATE message indicating that the resource has been successfully allocated to the called terminal in step 427. Thereafter, in step 429, a 200 OK response message is received from the called terminal. The called terminal performs an alerting function (Alerting) in step 431 and transmits a 180 Ring message to the MGCF 121 to inform the calling terminal that the ring is ringing at the called terminal. The MGCF 121 transmits an ACM message to the MSC 151 in step 433.

When the called terminal transmits a 200 OK message indicating that the voice call is connected in step 435 to the MGCF 121, the MGCF 121 transmits an ANM indicating that voice call setup is completed in step 437. Then, the MGCF 121 notifies the IMS-MGW 123 that the call is connected in step 439 and instructs the traffic path setup. Thereafter, the MGCF 121 transmits an ACK message to the called terminal in step 441 to complete the call setup.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention can support voice services between heterogeneous networks in the IMS system, thereby enabling IMS-based wired and wireless integrated services. In addition, operators that provide services such as wireless Internet and WCDMA can also provide voice services, which may increase demand, resulting in increased sales.

Claims (5)

In the IMS (IP Multimedia Subsystem: IMS) system that interoperates a network providing an IP packet-based data service and a network providing a circuit-based voice service, A Call Session Control Function (CSCF) unit for handling calls and sessions of the networks using a Session Initiation Protocol (SIP); A home subscriber server (HSS) for storing an integrated profile of the data service and the voice service subscriber and transmitting the profile to the CSCF if necessary; A Media Gateway Control Functon (MGCF) which performs resource allocation and signaling processing when establishing a call between mutual networks; A media gateway (MGW) for converting traffic between networks under the control of the MGCF, The system, characterized in that it comprises a mobile terminal capable of receiving services of the networks. The method of claim 1, wherein the CSCF unit, A proxy CSCF unit for connecting to a network interworking with the IMS system when establishing a call; And a serving CSCF unit configured to receive the integrated user profile from the HSS and provide a service when authenticating in the interworked network. The method of claim 2, The system characterized in that it further comprises an integrated CSCF that serves as a point of contact for all incoming calls when connected to the external IMS system and performs a firewall role in the IMS system for security if necessary. The method of claim 1, The Internal Mobile Subscriber Identifier (IMSI) of the mobile terminal is included in a field of a registration message of the SIP. In the registration method in the IMS (IP Multimedia Subsystem: IMS) system interworking a network providing an IP packet-based data service and a network providing a circuit-based voice service, Requesting registration setting to the IMS system through the corresponding network to which the mobile station uses a SIP registration message; Registering a location using an integrated subscriber profile when the registration request is made; And deleting the location registration from the network if the corresponding network was a network providing a voice service.

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