The IMS-based Control Architecture of IPTV Service

The IMS-based Control Architecture of IPTV Service HyunSoon Shin, IT Convergence Technology Research Laboratory Electronics and Telecommunications Research Institute 161 Gajeong-dong, Yuseong-gu, Daejeon, 305-350 KOREA Abstract: - This paper designs for the IMS-based control architecture of the IPTV service on NGN, proposes the service control method. The proposed control architecture of the IPTV service adds the IPTV multicast session control function to the CSCF(Call Session Control Function) of IMS so that IMS can control not only the existing communication service but also the broadcasting service. And it adds the profile management functions of the HSS subscriber to management for the IPTV subscriber. Also by constructing the information management function of the multicast group and the information management function of service(contents) additionally, the IPTV service interworking with the functions of IMS is controlled. Key-Words: IPTV, IMS 1 Introduction We are constructing a BcN(Broadband Convergence Network) which a convergence service supply merging the communication and broadcasting is possible[1]. Therefore, the BcN needs a control technique like IPTV(Internet Protocol Television) of a convergence service. The IPTV service can be defined to support the convergence service including VoD, broadcasting and communication service for the next generation. It is provided through the IP based broadband network and the TV. Many vendors of enterprises are currently offering a non-standard IPTV service. This has the limit with the interoperability at mostly universal service. Consequently, we are hastening the standardization about the IPTV service technique at an international standardization instrument(itu-t, ATIS, etc..) and TTA(Telecommunications Technology Association) [2][3][4][5]. The standardizing project for the control architecture of the IPTV service started the study of the global IPTV standard by organizing ITU-T FG IPTV. Including the IMS-based and the non-ims-based IPTV control architecture on NGN, the IPTV control architecture on non-ngn is considered. IMS[6][7][8] is established as the key technology to provide the new service under the All-IP-based future communication conditions. The request for the control technology of IMS-based IPTV and technology components in this paper is drawn. And the control architecture, the control method of IPTV service is presented. This paper is constructed as following. Firstly, in Section 2, the problems of the IPTV control architecture and features of the IPTV IMS-based control architecture are looked into, in Section 3, the IMS-based IPTV control architecture is designed, in Section 4, IPTV control method is presented, in Section 5, the conclusion with prospect from now on is made. 2 IPTV Service 2.1. IPTV Service Concept IPTV is the converged service of the communication and the broadcasting, which offer the multi-channel broadcasting service as the public, charging channel broadcasting to TV terminal through the internet-based BcN that quality is guaranteed. Unlike the existing broadcasting service, the IPTV service transmits broadcasting contents through internet. Therefore, a communication service and a broadcasting service within communication networks or subscriber device are converged, so that various applied higher value-added service is possible. The IPTV service will pass through the bundled service stage to deliver the multi-channel broadcasting contents through the IP-based networks, be This work was supported by the IT R&D program of MIC/IITA. [2008-S-001-01, Development of IT based Total Solution for Shipbuilding] ISSN:1790-5109 299 ISBN: 978-960-474-002-4

personalized, and develop into the two-way TV service. And finally we can expect to be provided a service through the mobile terminal continuously. The IPTV service as shown on Fig. 1, can be divided into a broadcasting service, a communication service, and a convergence service converged broadcasting and communication. (Fig. 1) IPTV Service Concept 2.2. The problems of the IPTV architecture and the feature of the IMS-based architecture 2.2.1 The problems of the present architecture The IP-based multimedia service can be divided into three types: a session-based communication service, a broadcasting service, and a web service. To control these services, a session-based communication service takes the IMS control architecture. Whereas, all the service functions in the broadcasting service is located in the subscriber terminal and the Head-End. It is the Client-Server architecture that its network delivers only the media and the service control signaling message. Namely, the present service control architecture can be the over-lay architecture that the session-based communication service is not related to the broadcasting service. Therefore, the present client-server architecture in terms of whole networks becomes complicated by a increasing service, has problems of the profitability reduction by the limit of the various added service including the convergence service, the increase of CapEx/OpEx because of the not-unified architecture, and the quality control limit, the scalability limit caused by lack of the integrated resource management function. Accordingly, new service control architecture to overcome this limit, is needed. The problems of the present architecture are as follows. (1) not recognizing the session of the service - lacking in traffic monitoring, status management (2) being the non-standard service of the existing IPTV service (3) being restriction to support the customer customization QoS (4) being restriction to support the converged, added service (5) being the interoperability delicate (6) being the architecture dependent on service. - being the limit to support various services - being restriction in blending - being restriction supporting various contents 2.2.2 The feature of the IMS based architecture The control function for the IPTV service is incorporated into the existing IMS-based service control architecture, so that it can reduce the CapEx/OpEx, can systematically unite the general control, such as the control, status management of service session, the QoS control, the access security control and the charging, and so forth. (1) The merits in using the existing technology - IMS has the common architecture useful for implementing various applications. - IMS can improve the ability of the service supplier, operate the new service. - Needful resource is reduced to operate application. (2) It is possible to charge the unit of the service, the program and the contents. (3) It is possible the creation of the service uniting each service like CS, BS, Web. (4) It is guaranteed the SIP-based authentic scalability. (5) Interoperability by using the standard is guaranteed. 3. IMS-based IPTV Control Architecture Design 3.1. A design concept The IPTV service is the IP-based broadcasting service that the communication of the information and the sense is possible, and that the subscriber and the contents can easily be accommodated extendedly. Therefore, it must be designed so that network attachment irrelevant to user s terminal, place, network, can be possible. And by recognizing automatically the service profile, the quality requirement, and the network mobility, it must be designed to provide the service type united communication and broadcasting easily. Also the ISSN:1790-5109 300 ISBN: 978-960-474-002-4

architecture that construction component needful as introduction of new service can be applied easily, must be designed. Design rule is as follows. - having an intention of providing the IPTV service in BcN - having the control architecture of the IPTV service based on NGN architecture - designing with the expansion concept based on the IMS architecture - The scope of admission in control class of existing Head-End function is as follows.. Subscriber Manager Function. Group Manager Function. Session Manager Function. Resource Manager Function - The scope of control converged by using SIP protocol is as follows.. Call session control Function. Multicast session control Function. Streaming session control Function - The channel zapping function uses SIP and IGMP. - It uses SIP the session control function for VoD streaming media service. - It uses RTSP the VCR-like control function. 3.2. Architecture Outline To control the broadcasting service as well as the existing communication service, the session control function (CSCF) of IMS and the management function of subscriber profile are expanded, the information management function of the multicasting group and the service(contents) information management function are added. By uniting control of the IPTV service under the IMS architecture, the systematic convergence control is possible, so it is the useful architecture to support the blended service. By putting message conversion function separately for the IPTV service for the existing terminal(non-sip) subscriber, the IGMP and the RTSP message is converted into the SIP message, so the call/session control function of IMS is supported. For the contents service of real VoD type, the trick mode play like pause, rewind, fast forward, and resume demanded in VoD service, must be supported. The function for trick mode play in the present SIP protocol is not being guaranteed. To settle this problem, this paper is designed to use the RTSP for the VCR-like control. 3.3. The Proposed IPTV Control Architecture (Fig 2.) IPTV Functional Architecture Fig. 2 shows Functional Architecture for IMS-based IPTV service. Each function components is looked into. 3.3.1. Contents Creator The creator(server) of service/contents corresponds to the contents(broadcasting) server. The contents creator makes the service(contents) by inter-working with the CGMF(BGMF,BCMF), manages the information of service and contents in networks. And this information is used while controlling the IPTV service. 3.3.2. Service/Session Control The IPTV service session control has the architecture expanded CSCF of IMS. The following functions are supported in each expanded CSCF. (1) HSS(Home Subscriber Server) The HSS manages the profile of the IPTV subscriber. The HSS performs functions of registration, deletion and information update. (2) S-CSCF(Serving Call/Session Control Function) The S-CSCF performs the registration function, the authentication function and the authorization function for the IPTV subscribers. The S-CSCF performs the unicast session control function and the multicast session control function. The S-CSCF performs the stream service point trigger function. The S-CSCF allocates the media server. The S-CSCF performs the routing function to the application server or the broadcast server. The S-CSCF performs the multicast charging function. The S-CSCF stores server address, ISSN:1790-5109 301 ISBN: 978-960-474-002-4

the FC priority order, default processing method, authentication data, service information on HSS. (3) I-CSCF(Interrogating Call/Session Control Function) The I-CSCF performs form security associations among the different network. (4) P-CSCF(Proxy Call/Session Control Function) The P-CSCF performs QoS control function by using PDF. The P-CSCF manages resource for the multicast. The P-CSCF performs the multicast branching interface function. The P-CSCF supports the bandwidth information of each session. (5) IACF(IPTV Access Control Function) The IACF performs the message conversion(between RTSP and SIP, between IGMP and SIP) function. The IACF performs the authentication function for channel adaptation or service adaptation. The IACF performs the user agent function(interface with clients). (6) CGMF(Service/Contents Group Management Function) The CGMF is similar to the function of HSS. The CGMF manages the profile for contents, service. The created contents is registered in the CGI by the CGMF and used with session configuration information. - The CGMF creates and manages the contents information(the channel list, the service authentication level) while interworking with contents creator. - The CGMF performs the group address assign function, the group membership management function and the member list update function. The MRPF supports the handing function of payload of packet. The MRPF performs the media mixing function by the MRCF control. The MRPF supports the function of trans-coding, video mixing, conference bridge, data conference, TTS, voice/video recoding and voice recognition. The MRPF performs the function of the broadcasting stream encoding and transmission. The MRPF performs the function of the contents(cod) streaming transmission. (2) RACF(Resource Admission Control Function) The RACF performs the function of the resource control based QoS. (3) NACF(Network Attachment Control Function) The NACF performs the function of the network attachment handling. The NACF performs the function of the multicast branching handling. 4.3.4. Terminal (User Device) Control (1) STB(Set-Top Box) It performs the function of the session starting handling(user agent function). It performs the function of the EPG analysis and handling. 4. IPTV Service Control Mechanism 4.1. IPTV Contents Creation (7) MRBF(Multimedia Resource Broker Function) The MRBF allocates the media server resource. It manages the media server resource information of the media server. It performs the media server use-rate information management function. (8) MRCF(Multimedia Resource Control Function) The MRCF controls the MRPF. The MRCF assigns the resource of the MRPR for the service like announcement. The MRCF assigns the resource of the MRPF for streaming service. The MRCF performs the user agent function for the server. 3.3.3. Transport Control (1) MRPF(Multimedia Resource Processing Function) (Fig. 3) IPTV Contents Creation Procedure ISSN:1790-5109 302 ISBN: 978-960-474-002-4

Fig. 3 shows the process creating the new contents for the IPTV service. 1 The contents server(broadcasting server) informs CGMF of new contents creation. 2 The CGMF creates the new contents information. 3 It request creation of multicast group in the new contents or channel. 4 It creates the multicast group.. It creates the group address.. It begins in the group membership management. 5 It loads the contents or the group information to the S-CSCF. 6 Contents Server makes new the EPG. 7 It makes a down loading new EPG to the STB. 8 It ends the content(service) creation by performing a channel mapping between CGMF and STB. 9 CGMF informs the content server(broadcasting server) of performing OK. 3 It requests the IPTV subscriber registration to the S-CSCF. 4 The S-CSCF interworks the HSS and registers the IPTV subscriber. 5 A profile of a registered subscriber is made a loading and used for the session set-up information. 6 It made a down load EPG a registered IPTV subscriber STB. 7 EPG makes a display in a subscriber terminal. 4.3. IPTV Session Set-up A number analysis of maximum admission channels EPG menu selection starting session set-up yes basic channel? no (STB) (STB P-CSCF/IACF) 4.2. IPTV Subscriber Registration QoS control (resource requirement analysis) (P-CSCF) service level authentication (S-CSCF CGI) session admission control (P-CSCF/S-SCSF) Request resource reservation (P-CSCF -> RACF) Request multicast switching (P-CSCF -> NACS) Session set-up (S-SCSF MRCF) Starting multicast group membership management (S-SCSF -> CGMF) Interworking with presence server (Service status information publish) (S-CSCF Presence server) Session information update (S-CSCF HSS) Streaming copy (Multicast router) (Fig. 4) IPTV Subscriber Registration Procedure Fig. 4 shows the procedure subscriber registration. 1 If the STB is in a condition of power on, authenticates the network attachment and assign IP. 2 It performs configuration in STB. Stream transmission (Fig. 5) IPTV Service Session Set-up Procedure Fig. 5 shows a process of session set-up of IPTV service. The procedure is as follows. 1 It picks up a channel(service) in the STB(TV) EPG menu. ISSN:1790-5109 303 ISBN: 978-960-474-002-4

2 STB makes request to the control layer(p-cscf) a session set-up. 3 It analyzes the channel and the resource requirement. 4 It authenticates the service level. 5 It performs a session admission control. 6 It makes a request of resource reservation to RACF. 7 It makes a request of multicast switching. 8 It set up between STB and MRCF(STB -> IACF -> P-CSCF -> S-CSCF -> MRCF). 9 It begins in the multicast group membership management for the session and changes membership information. 10 Interworking with the presence server, it publishes the service status information. 11 It changes the session information. 12 It copies a stream, and then transmits the stream to the user. 5. Conclusions This paper designed the IMS-based control architecture of the IPTV service, proposed a service control method. The proposed control architecture of the IPTV service added the control function of the IPTV multicast session to session control function(cscf) of the IMS so that the IMS can control the broadcasting service as well as existing communication service. And it added the management function for the IPTV subscriber to subscriber profile management function of HSS. Also by the constructing information management function block of the multicast group and information management function of the services(contents) in addition, the IPTV service is controlled while inter-working with the function blocks of IMS. Features of the proposed architecture are as follows. - By merging, controlling the IPTV service under the IMS architecture, the systematic convergence control is possible, and the blended service is convenient for use. - By putting the message conversion function separately for the IPTV service of the existing terminal(non-sip) subscriber, IGMP and RTSP message is converted into SIP message, call/session control function of the IMS is supported. - The control and management of the multicast session in the CSCF of the IMS is performed. - HSS of the IMS gets the IPTV subscriber information accepted, managed. - While creating contents, the control class is intended to inter-work with the contents server, to manage the information of contents. - By constructing management for the contents the information and the management function of Multicast group in addition, it is intended to use for the IPTV service control. - The VCR-like control function is controlled by using RTSP. The IPTV service is established as a flourishing service of next generation network. We will discuss, propose, and standardize for the IPTV service control technology. First of all, our remaining project is to study, develop the control architecture of the IPTV service for being given the IPTV service of higher quality. References [1] JeongHee Bang, A consolidation profile setup strategy in BcN foundation, Workshop for the key point technique of BcN, 2006. 8. [2] ETSI ES 282 007 v1.1.1: Telecommunications and Internet Converged Service and Protocols for Advanced Networking(TISPAN); IP Multimedia Subsystem Functional Architecture, June 2006. [3] ETSI ES 182 012 v1.1.1: Telecommunications and Internet Converged Service and Protocols for Advanced Networking(TISPAN); IMD-based PSTN/ISDN Emulation Subsystem; Functional Architecture, Apr 2006. [4] Kwihoon Kim, Hyunwoo Lee, and Won Ryu, Proposed Addition of Transport Stratum User Profile in Draft Q.NGN-trx.profile, ITU-T COM11-D-143, July 2006. [5] Naotaka Morita, Functional Requirements and Architecture of NGN, ITU-T Y.2012, July 2006. [6] 3GPP TS 23.002 v7.1.0: Network Architecture, Mar. 2006. [7] 3GPP TS 23.228 v7.4.0: 3rd Generation Partnership Project; Technical Specification Group Services, and System Aspects; IP Multimedia Subsystem(IMS);Stage 2(Release 7), June 2006. [8] Gonzalo Camarillo, Miguel-Angel, and Garcia-Martin The 3G IP Multimedia Subsystem(IMS): Merging the Internet and the Cellular Worlds, Wiley & Sons, ISBN 0-470-01818-6, 2006. ISSN:1790-5109 304 ISBN: 978-960-474-002-4