Patent Publication Number: US-2007124438-A1

Title: Method and system for providing service control and brokering in IMS-based telecommunication system

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims priority to and the benefits of Korean Patent Application Nos. 10-2005-0114161 and 10-2006-0036569 respectively filed in the Korean Intellectual Property Office on Nov. 28, 2005 and Apr. 24, 2006, the entire contents of which are incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      (a) Field of the Invention  
      The present invention relates to a communication system based on an Internet Protocol (IP) Multimedia Core Network Subsystem (IMS), and more particularly, relates to a method for registering, controlling, and brokering services in a visited network, and a system using the same.  
      (b) Description of the Related Art  
      In general, a user is always provided with services through a service control device such as a serving call state control function (S-CSCF) that handles service control of a home network even when the user moves from the home network to a visited network in an IMS-based communication system. Such a service control scheme has a drawback of providing services inefficiently.  
      That is, service control in the visited network always goes through the service control device in the home network, thereby causing triangle routing. Also, the service control in the visited network is handled by the service control device in the home network since the service control device in the home network selects a service control device in the visited network, and therefore it is difficult to efficiently provide local services to the user. Further, it is also difficult to provide local services adapted to the user since the visited network does not have a profile of the user.  
      In addition, service brokering should be performed on the basis of context information so as to provide a user roaming to the visited network with a service that is adapted to the context information. However, the service control of the home network according to the prior art cannot provide the user with services adapted to the context information.  
      The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention has been made in an effort to provide a service control and service brokering method that enables a visited network to directly provide a user with local services rather than going through a home network in an IMS-based communication network, and a system using the same.  
      In addition, the present invention provides a service control and service brokering method that enables a visited network to provide a user with optimal services that are adapted to a profile of the user, and a system using the same.  
      In an Internet Protocol multimedia core network subsystem (IMS)-based communication system that includes a home network and a visited network, an exemplary service brokering system according to an embodiment of the present invention controls services through user equipment in the visited network when a user moves to the visited network from the home network. Herein, the service broker system is located in the visited network.  
      The service brokering system includes a proxy session control device, an interrogating session control device, and a visited-home network subscriber server. The proxy session control device performs as a contact point for the user equipment. The serving session control device controls a service to be provided to the user equipment. The interrogating session control device searches for a serving session control device that handles the service control upon a request of the proxy session control device. The visited-home network subscriber server receives user information and profiles of the user from the home network, and manages the information and the profiles.  
      An exemplary service registration and control method in an IP multimedia core network subsystem (IMS)-based communication system that includes a home network and a visited network according to an embodiment of the present invention performs service registration and control in the visited network by using user equipment. Herein, the service brokering system is a service brokering system located in the visited network.  
      The service registration and control method includes (a) the user equipment registering services to the home network with inclusion of a local service control request; (b) in the case that local service control is allowed to the user equipment, the user equipment receiving a service registration confirmation message that contains information on the allowance of the home network on the local service control; (c) after receiving the service registration confirmation message, the user equipment requesting local service registration to the service brokering system; and (d) the user equipment receiving a local service registration confirmation message from the service brokering system.  
      An exemplary service registration and control method in an IP multimedia core network subsystem (IMS)-based communication system that includes a home network and a visited network according to an embodiment of the present invention performs registration and control of a service to be provided to user equipment by using the service brokering system.  
      The service registration and control method includes (a) the service brokering system transmitting a service registration request message that is transmitted from the user equipment to the home network; (b) the service brokering system receiving a service registration confirmation message from the home network in response to the service registration request message, the information containing information on allowance of local service control; (c) in the case that the user equipment service requests local service control, the service brokering system registering the user equipment as user equipment to be receiving local services; and (d) the service brokering system providing services to the registered user equipment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a configuration diagram of a service network where an S-CSCF in a visited network performs service control via an S-CSCF in a home network in a typical IMS-based communication system.  
       FIG. 2  is a configuration diagram of a service network that performs service control and service brokering in a visited network according to an exemplary embodiment of the present invention.  
       FIG. 3  is a flowchart of a service registration process for a subscriber according to an exemplary embodiment of the present invention.  
       FIG. 4  is a flowchart showing service control and service brokering methods of a home network upon a subscriber&#39;s service request according to an exemplary embodiment of the present invention.  
       FIG. 5  is a flowchart showing service control and service brokering methods of a visited network upon a subscriber&#39;s service request according to an exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
      In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.  
      In addition, throughout this specification and the claims which follow, unless explicitly described to the contrary, the word “comprise/include” or variations such as “comprises/includes” or “comprising/including” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.  
      An Internet Protocol multimedia subsystem (IMS)-based communication system controls multimedia services and performs service brokering as shown in  FIG. 1 .  
       FIG. 1  illustrates a service network structure in which a serving call state control function (S-CSCF) in a visited network performs service control via an S-CSCF in a home network in a typical IMS-based communication system.  
      In  FIG. 1 , when user equipment (UE)  10  moves to a visited network  20  from a home network  30 , the UE  10  is connected to a proxy call state control function (P-CSCF)  21  located in the visited network  20  and that is provided with services. At this time, the UE  10  transmits a message that contains a uniform resource identifier (URI) to the visited network  20 , wherein the URI is a message header indicating that local service control is requested.  
      Upon the service control request from the UE  10 , the P-CSCF  21  in the visited network  20  requests service control to an S-CSCF  31  that handles service control of the home network  30 . Then the S-CSCF  31  transmits a service control message to an external service platform  40 . At this time, the external service platform  40  checks whether the S-SCSF  31  accepts the user-requested local service control.  
      In the case that the acceptance of the local service control is confirmed, the S-CSCF  31  in the home network  30  transmits a message to the S-CSCF  22  in the visited network  20  to request the local service control, and the S-CSCF  22  handling service control of the visited network  20  performs the local service control. In addition, the S-CSCF  31  in the home network  30  transmits a service control message to the S-CSCF  22  handling the service control of the visited network  20  and provides local services.  
      In such an IMS-based communication system, a user is always provided with services via an S-CSCF in a home network even though the user is roaming from the home network to a visited network. In addition, the user cannot be provided with appropriate local services from the visited network since the visited network does not have a profile of the user.  
      Therefore, a method and a system for service control and service brokering according to an exemplary embodiment of the present invention can efficiently offer services.  
       FIG. 2  is a configuration diagram of a system that performs service control and service brokering in the IMS-based communication system according to an exemplary embodiment of the present invention.  
      As shown in  FIG. 2 , in the IMS-based communication system, user equipment (UE)  330  can still be provided with the same service that the UE  330  was previously provided in a home network  310  even after the UE  310  moves to a visited network  320 . The system according to the exemplary embodiment of the present invention performs service control and service brokering in order to provide the same service to the UE  330  in the visited network  320 .  
      For this purpose, the system according to the exemplary embodiment of the present invention includes a P-CSCF  322 , an interrogation call session control function (I-CSCF)  323 , an S-CSCF  324 , and a visited-home subscriber server (V-HSS)  325 , and is connected to a service provider (SP)  329  through a service platform  326 . Hereinafter, the system in the present embodiment will be called a service brokering system. Since the service brokering system is a part of the visited network  320 , the visited network  320  will be hereinafter understood as the service brokering system for better comprehension and ease of description.  
      With such a configuration, the visited network  320  is connected to the home network  310  and performs service control and service brokering.  
      The home network  310  also includes an S-CSCF  314 , an I-CSCF  313 , a P-CSCF  312 , and an HSS  315  in order to provide services to the UE  10 , and is connected to the SP  319  through a service platform  316 .  
      In each network, the P-CSCFs  312  and  322 , which are the first contact points within the IMS for the user, register user information from the visited network  320  to the home network  310  and forward a transmitting/receiving call request to the home network  310 . That is, the UE  330  located in the home network  310  requests a service from the P-CSCF  312  in the home network.  
      Herein, the UE  330  may be provided as a mobile terminal (MT) that performs radio transmission and radio transmission-related functions, terminal equipment (TE), or a communication terminal that performs a terminal adaptation function (TAF). In this case, the UE  330  communicates with the P-CSCFs  312  and  322  using a session initiation protocol (SIP).  
      The I-CSCFs  313  and  323  select an S-CSCF that is appropriate for the user&#39;s call request from a plurality of S-CSCFs, and hide configuration information on the S-CSCF  314  in the home network  310  from other networks for the purpose of security. The I-CSCF  313  receives a message from the P-CSCFs  312  and  322  that have received a service request, searches for a correct S-CSCF  314  from the HSS  315 , and transmits a response message to the P-CSCF  312 .  
      At this time, the P-CSCFs  312  and  322  communicate with the I-CSCFs  313  and  323  using the SIP, and the I-CSCFs  313  and  323  communicate with the S-CSCFs  314  and  324  using the SIP. On the other hand, the I-CSCF  313  communicates with the HSS  315  using a diameter protocol. Herein, the diameter protocol is an IETF standard protocol that has been developed for the next generation portable Internet and a roaming network, and is utilized for authorization system development in the next generation network such as a public wireless local area network, a portable Internet, and a wideband convergence network.  
      The S-CSCFs  314  and  324  handle service control for a user in an IMS network. That is, the S-CSCFs  314  and  324  registers with the HSS  315  as servers controlling sessions of the UE  330  and download and stores registration information of the user. The S-CSCFs  314  and  324  handle call/sessions of a registered user and control services. Also, S-CSCFs  314  and  324  provide service resource-related information to the user.  
      The HSS  315  is a database of all users, and manages user profiles and a physical location of the user and performs authorization and authentication of the user. That is, the HSS  315  stores information on all users in the IMS network, and communicates with the S-CSCF  314  using the diameter protocol.  
      The service platforms  316  and  326  deliver services provided from the SPs  319  and  329  to the IMS network, and include context managers  318  and  328  and service brokers  317  and  327 . The context managers  318  and  328  manage context information that is required for providing a context-adapted service to a user in the visited network  320 . Herein, the context information is data collected by continuously monitoring a current condition of the user, particularly a condition of a visited network, so as to adapt services to a user&#39;s current circumstance and select and access an optimal network.  
      The service brokers  317  and  327  perform service brokering, and are capable of providing a service that is adapted to a user&#39;s profile based on the user&#39;s information that has been provided during registration. That is, the service brokers  317  and  327  adapt services to be offered to the user service device on the basis of the context information collected by the context managers  318  and  328  and the profile of the user.  
      The SPs  319  and  328  implement services through a service application program interface (API) provided by the service platforms  316  and  326 , and provide the services to the UE  330 .  
      A configuration in the visited network  320  for providing services to the UE  330  will now be described, wherein the configuration includes the above-described constituent elements.  
      The visited network  320  has constituent elements that are similar to those of the previously described home network  310 . However, additional constituent elements are required to provide a local service to the UE  330  located in the visited network  320 .  
      The P-CSCF  322  transmits a service request message to the I-CSCF  313  in the home network  310  and the I-CSCF  323  in the visited network  320  in order to search for a correct S-CSCF  314  that handles service control of the home network  310 . Herein, the I-CSCF  323  searches for an S-CSCF  324  from the V-HSS  325  and transmits the search result to the P-CSCF  322 .  
      The V-HSS  325  functions the same as the HSS  315  in the home network  310 . In addition, in the case that the user is roaming to the visited network  320 , the V-HSS  325  receives information on the user from the HSS  315  in the home network and manages the information.  
      Based on such a structure, a service providing method according to an exemplary embodiment of the present invention will now be described. Particularly, a method for service control and service brokering in the visited network will be described in more detail with the case that the user is roaming from the home network  310  to the visited network  320 .  
      Through a network that is capable of performing the service control and service brokering shown in  FIG. 2 , a user service registration process will be described with reference to  FIG. 3 .  
       FIG. 3  is a flowchart showing a service registration process of a user according to an exemplary embodiment of the present invention.  
      As shown in  FIG. 3 , the user having moved to the visited network  320  requests service registration to the P-SCSF  322  using the UE  330  in order to receive services from the visited network  320  in step S 100 . Accordingly, the UE  330  transmits a first SIP register message (also called a service registration request message) to the P-CSCF  322  in the visited network  320  in step S 100 .  
      The first SIP register message is used for registering service preference information to a P-CSCF  322  in a new visited network in order to receive a user-preferred service. At this time, the first SIP register message contains information about whether the user requested local service control is included in the message and an inquiry on whether the visited network is capable of performing local service control.  
      The P-CSCF  322  of the visited network  320  transmits the first SIP register message to the I-CSCF  313  in the home network  310  in order to transmit the message to the S-CSCF  314  that handles service control of the home network  310 , in step S 110 . In order to search for the S-CSCF  314  to which the user information is registered from among a plurality of S-CSCFs in the home network  310 , the P-SCSF  322  in the visited network  320  transmits the first SIP register message to the I-SCSF  313  that directly communicates with the S-CSCF  314  using the SIP.  
      The I-CSCF  313  in the home network  310  queries the HSS  315  to search for the S-CSCF  314  that controls user-wanted services in step S 120 . That is, the I-CSCF  313  transmits a query language to the HSS  315  to search for the S-CSCF  314 . When the S-CSCF  314  is searched, the I-CSCF  313  transmits the first SIP register message that has been transmitted from the visited network  320  to the searched S-CSCF  314  in step S 130 .  
      After receiving the first register message, the S-CSCF  314  registers the user and updates user information to the HSS  315  in step S 140 . At this time, the S-CSCF  314  determines whether the visited network  320  is capable of performing local service control in step S 150 . In the case that information on capabilities of performing a local service control of a plurality of visited networks are predetermined by policy and stored in the S-CSCF  314  of the home network  310 , whether the visited network  320  is capable of performing a local service control can also be determined by searching for the corresponding information from the S-CSCF  314  in the home network, but it is not restrictive.  
      In the case that the visited network  320  is capable of performing the local service control and the first SIP register message contains a user&#39;s request on the local service control, the S-CSCF  314  in the home network  310  transmits a registration result to the I-CSCF  313  by sending a SIP  200  OK message (also called a service registration confirm message) thereto in step S 160 . The SIP  200  OK message is transmitted to the P-CSCF  322  in the visited network  320  through the I-CSCF  313  in the home network  310  in step S 170 , and is then transmitted to the UE  330  in step S 180 . Herein, the  200  OK message is a response message informing that the SIP message has been successfully received.  
      In the case that a result of the determination of the capability of performing the local service control in the step S 150  shows that the visited network  320  is not capable of performing the local service control, the user registration process is terminated in step S 180 . However, in the case that a user located in the visited network  320  requests local service control and the S-CSCF  314  located therein allows the local service control, local service registration is additionally performed through processes in a block of S 200  in  FIG. 3 . The local service registration process means that a user having entered the visited network  320  registers with the S-CSCF  324  in the visited network  320  through the user&#39;s UE  330  so as to receive services through the UE  330 .  
      In the local service registration process, the UE  330  firstly transmits a second SIP register message (also called a local service registration request message) to the P-CSCF  322  in the visited network  320  in step S 201 . The P-CSCF  322  transmits the second SIP register message to the I-CSCF  323  in the visited network  320  in order to forward the second SIP register message to the S-CSCF  324  that handles service control for the user in the visited network  32  in step S 202 .  
      The I-CSCF  323  queries the V-HSS  325  in order to search for the S-CSCF  324  that directly control services requested by the user among a plurality of S-CSCFs in step S 203 . The I-CSCF  323  transmits the second SIP message to the searched S-CSCF  324  in step S 204 . After receiving the second SIP register message, the S-CSCF  324  forwards the second SIP register message to the I-CSCF in the home network  310  in order to inform the local service registration in step S 205 . Thus, the second SIP message that contains information on the user local service registration is forwarded to the S-CSCF  314  in the home network  310  from the S-SCSF  324  in the visited network  320  in step S 205 .  
      The I-CSCF  313  in the home network  310  queries the HSS  315  to search for the S-CSCF  314  that performs service control for the user in step S 206 , and forwards the second SIP register message to the searched S-CSCF  314  in step S 207 . After receiving the second SIP register message, the S-CSCF  314  registers local services for the user and updates the user information to the HSS  315  in step S 208 .  
      The S-CSCF  314  transmits a result of the service registration using a SIP OK message (also called a local service registration confirmation message) in response to the second SIP register message in step S 209 . Then the SIP OK message is transmitted to the S-CSCF  324  in the visited network through the I-CSCF  313  in the home network  310  in step S 210 . After updating user information to the V-HSS  325  based on the SIP  200  OK message in step S 211 , the S-CSCF  324  transmits the SIP OK message transmitted from the home network  310  to the I-CSCF  323  in step S 212 . The I-CSCF  323  forwards the SIP  200  OK message from the S-CSCF  323  to the P-CSCF  322  and the P-CSCF  322  transmits the message to the UE  330 , and the service registration process for the user who requested the local service control is terminated.  
      The following will describe a process for providing services to the user who has completed service registration in the home network  310  in the case that the visited network  320  is incapable of performing local service control or the case that the visited network  320  is capable of performing the local service control.  
       FIG. 4  is a flowchart showing a method for service control and service brokering in a home network upon a user&#39;s service request according to an exemplary embodiment of the present invention.  
      As shown in  FIG. 4 , a user roaming from the home network  310  to the visited network  320  requests services through the UE  330 . At this time, the UE  330  transmits a service request message to the P-CSCF  322  located in the visited network  320  in the case that the service requested by the user requires service control of the home network  310  in step S 300 .  
      Since a routing path of the service request message is set to go through the S-CSCF  314  in the home network  310 , the P-CSCF  322  transmits the service request message to the S-CSCF  314  that handles service control in the home network  310  of the user in step S 310 . The service request message contains the message routing path and information on whether the service requested from the user through the UE  330  requires service control of the home network  310  or service control of the visited network  320 .  
      Upon the user&#39;s service request, the S-CSCF  314  in the home network  310  forwards the service request message to the service broker  317  in step S 320 . The service broker  317  requests a user profile from the HSS  315  in order to provide an optimal service to the user who requested the service in step S 330 .  
      After receiving the user profile from the HSS  315 , the service broker  317  transmits a service response message to the S-CSCF  14  to provide a service adapted to the user profile in step S 340 . The S-CSCF  314  in the home network  310  forwards the service response message to the P-CSCF  322  in the visited network  320  in step S 350 , and then the service response message is transmitted to the UE  300  in step S 360 .  
      In the case that the visited network  320  is capable of performing the local service control, a process for providing a user with the same service that the user previously received in the home network  310  in the visited network  320  will now be described with reference to  FIG. 5 .  
       FIG. 5  is a flowchart showing a method for service control and service brokering according to a user&#39;s service request according to an exemplary embodiment of the present invention.  
      As shown in  FIG. 5 , a user located in the visited network  320  requests a service that requires local service control and is provided with the service through the process of  FIG. 5 . First, the user requests a service through the UE  330 , and then the UE  330  transmits a service request message to the P-CSCF  322  in the visited network in step S 400 . At this time, since the service request message is set to be transmitted via the S-CSCF  324  in the visited network  320  according to a routing path contained in the service request message, the P-CSCF  322  transmits the service request message to the S-CSCF  324  that handles service control of the visited network  320  in step S 410 .  
      The S-CSCF  324  in the visited network  320  transmits the service request message to the service broker  327  so as to provide a service adapted to the user in step S 420 . The service broker  327  requests user profiles from the V-HSS  325  to search for a profile of the user who has requested the service, in step S 430 . At this time, the service broker  327  may request the profile of the user from the HSS  315  in the home network  310  in the case that the profile is not stored in the V-HSS  325 , in step S 440 .  
      The service broker  327  transmits a service response message in response to the S-SCSF  324  request message to provide a service adapted to the user profile that has been provided from the HSS  315  in step S 450 . The S-CSCF  324  in the visited network  320  transmits the service response message to the P-CSCF  322  in the visited network  320  in step S 460 , and the service response message is transmitted to the UE  330  in step S 470  so that the user can be provided with the requested services through the UE  330 .  
      The method for service control and service brokering of the visited network  320  of  FIG. 5  is performed only when the local service control is permitted by the UE  300 . In the case that the UE  330  does not permit the local service control, the user in the visited network is provided with services from the home network  310  according to a typical method.  
      Herein, a program realizing functionalities that correspond to the configuration according to the above-described exemplary embodiment of the present invention or a recording medium in which the program is installed are also included in the scope of the present invention.  
      According to the above-described exemplary embodiment, the service control and service routing method can solve a triangle routing problem of providing services to a user in a visited network through an S-CSCF in the home network, and a service that is adapted to context information in the visited network can be provided to the user.  
      In addition, the user can receive services adapted to a profile and environment of the user, and a service provider can efficiently provide local services to a user in a visited network, thereby creating a source of profit.  
      While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.