1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.375.2 (06198) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions - General network requirements and functions Network capabilities to support IN provides only authentication
2、 and address information of Gateways and Servers; IN provides access to and use of Intelligent Peripheral (IP) with Specialized Resource Function (SRF) at Level 1 selection; IN provides Specialized Resource Function (SRF) at Level 2 selection. It is also assumed that Intelligent Network (IN) functio
3、ns (Figure 3) that encompass Broadband ISDN requirements are used as a target solution; i.e. in Figure 3, the IN functional elements SCP, IP, SCF, SRF, etc. cover besides N-ISDN also B-ISDN requirements. Besides other functionalities, the IN may provide Level 1 selection functionality for the Servic
4、e Provider Selection for multimedia services/applications. As an evolutionary step and in particular in smaller networks, VOD may also be implemented without the support of IN (Figure 2). These reference configurations also contain Network Management System functions (TMN). The reference configurati
5、ons given indicate Reference Points (RPs) between the functional elements. These are used to identi the physical interfaces and logical interrelations between the network elements of the VOD delivery system. The reference configuration presented in Figure 3 is intended as a solution in which ATM tra
6、nsport functions are used throughout the network. The evolutionary path to implement this reference configuration may be done in stages by using sub-configurations of this reference configuration (see, for example, subclause 4.2 on Access Network). Recommendation 1.375.2 (06/98) 3 STD-ITU-T RECMN 1.
7、375-2-ENGL 1998 m 48b259L Ob49530 407 m The reference configurations for VOD are represented by four major functional areas named as follows: Customer Premises Equipment Functions (CPE). o Access Network Functions (ACCESS). 0 ATM Core Network Functions (ATM CORE). 0 VOD Server System Functions. The
8、functional elements of these four areas and their functionality are described in detail in the following subclauses. A further description of the IN Functional Entities realized in the functional elements of the VOD delivery system is provided in Annex A. The selection mechanism provided by the VOD
9、Service to the user to select the information to be retrieved is a two-level selection mechanism: Level 1 offers the selection of the service provider (e.g. Level 1 gateway), and Level 2 offers the selection of the VOD content, i.e. of the video program, within a service providers domain. This two-l
10、evel selection mechanism is reflected in the VOD reference configuration by two individual functional elements of the VOD delivery system, one for the Level 1 selection: the Service Provider Selection may be provided by the network operator in the ATM core network functional area or by a separate se
11、rvice providers broker (or possibly also a service provider) and another for the Level 2 selection: the Content Selection (provided by the service provider in the VOD server system). This two-level selection mechanism is also reflected in the description of the functional interactions in clause 7. 4
12、.1 Customer premises equipment functions The functional area Customers Premises Equipment Functions (CPE) includes in the described scenario the functions of devices at the customers (users) home used to provide VOD. The functions of the CPE for VOD include the functions of Set Top Box (STB) and fun
13、ctions of the Terminal Equipment (TE). The TE, in the case of VOD in the residential environment, may be a TV set. The TE may also include existing equipment such as Work Stations, Personal Computer (PC), Telephone, etc., for VOD and/or other services. The STB functions present to the user various f
14、orms of menus and selection objects, and other typical graphical user interfaces. They contain the necessary hardware and software functions to provide VOD services in the home. The STB acts as an interface and an adaptation unit between the NT and the TE. The STB functions provide the platform on w
15、hich the services user application runs, and the infrastructure for user applications to offer sophisticated user interfaces. If the STB does not contain the procedures needed for control of selection processes and applications, the relevant software may be downloaded by an “STB Server“ in Figure 2
16、as part of the Service Related Control and in Figure 3 as part of the Intelligent Peripheral (IP) and/or the Content Selection as part of the VOD Server System. - Depending on the functional scenario, the STB may support a basic and partly optional set of features, as shown in Appendix I. The list o
17、f functions is not exhaustive and is provided as a basis for further study of network capabilities to support VOD. 4.2 Access network functions The Access Network Functions (ANF) support the physical interconnection and information transport of video streams (e.g. 1 S44-8 Mbitls), and of signalling
18、and interactive data and control bit streams between the CPE and the ATM Core Network (ATM node). Dependent on the different access media and topologies used, different access functions have to be provided. In the long term, network operators will preferably implement all-fibre access networks. But
19、in the short term, the introduction of VOD will be primarily based on existing and upgraded access infrastructures using different transmission media. The long-term and target solution will use ATM fiom the ATM core network till the CPE. But as evolutionary steps and as interim solutions, ATM may al
20、so be terminated in the AU of the access network. 4 Recommendation i.375.2 (06198) STD-ITU-T RECMN 1.375.2-ENGL 3998 W 4862593 Ob49533 343 The main alternatives of distribution technologies with different transmission media and topologies within the access network shown in Figure 4 are (not exhausti
21、ve): UTP (Unshielded Twisted Pair). Pure coax (current CATV). NOTE - CATV is upgraded by upstream channels. Upstream channels may also be provided by separate network, e.g. N-ISDN, PSTN. HFC (Hybrid Fibre Coax) with coax bus (concatenated fibre coax). HFC with coax star (concatenated fibre coax). Hy
22、brid Fibre UTP with UTP star (concatenated fibre coax). Broadband Passive Optical Network with ATM (BPON). Point-to-point fibre access network. The ANFs contain Network Termination Functions (NTFs) and Access Unit Functions (AUFS). 0 The NT terminates the public network and its functions support sev
23、eral interfaces to the user, e.g. for CATV, N-ISDN, B-ISDN (ATM), PSTN, etc. This includes transmission media such as Coax or Unshielded Twisted Pair (UTP) for broadcast and interactive video services, CATV, telephony, N-ISDN, B-ISDN, data access (e.g. Ethernet), or others respectively, via standard
24、 interfaces. The demarcation between the NT functions and the STB functions is indicated in Figures 2 and 3 as Reference Point 1 (RP1). However, it is open at this time what functions will remain in the STB and what will be implemented in the NT. The AU functions provide a standard (uniform) interfa
25、ce between the AN and the ATM CORE Network. Between the AU and the NT, several distribution technologies such as Hybrid Fibre Coax (HFC), Broadband Passive Optical Network (BPON), Radio, etc., may be used. In Figure 4, several AUS are shown, each of them dedicated to a particular transmission medium
26、. Depending on the access medium and topology used, one or several alternatives of access network functions are supported. The demarcation between the AN functions and the functions of the ATM Core Network (ATM node) is indicated as Reference Point 2 (RP2). - - 4.3 ATM core ne B-ISDN (ATM); (TBD) N-
27、ISDN; PSTN; etc. I RP3 P3 ATM Node Session Related TBD In Figure 2, the interface is UNI. If Figure 3 is applicable, the interface is TBD and INAP is used. ControVSCF SCF data is collected from the SCF, the SRF and the B-SSFCCF. . The SMF: provides service management capabilities for the SCF. This i
28、ncludes administration of all SCP data and large file management (e.g. routing addresses, feature intenvorking restrictions, etc.); supports the transmission of Service Logic program to the SCF; formulates and sends commands to activatedeactivate service logic programs to the SCF; receives, stores a
29、nd processes statistics and billing data from the SCF. This also includes storing “on-line“ statistical information; receives error or alarm messages from the SCF. Note that this function may alternatively reside in a TMN centre; provides access to configure the B-CCF/B-SSF trigger detection data; p
30、rovides access to control the content of the SRF navigation content. A content provider will be capable of updating the navigation video data via the SMF; Recommendation 1.375.2 (06/98) 21 e provides network security (e.g. password setting, access, etc.) function to ensure secure access of the funct
31、ional entities (i.e. SCF, SRF, B-CCFIB-SSF) it is required to manage; in a physical deployment of the broadband IN-architecture, resides in the Service Management Point (SMP). Appendix I Set top box features Functions for provision of the VOD applicatiodservice platform: Control of Service Provider
32、selection. Control of video selection (Service Platform). Support of video and audio stream downward and control stream bidirectional. Interactive control of video play (e.g. PLAY, PAUSE, etc.). MPEG decoding. Audio decoding. Provision of user interface platform. Infiared user control. Transmission
33、termination. Encryption (upstream). Decryption (downstream). Downloadable software (if necessary). Video and hi-fi stereo outpbts. Video text decoding. Cable tuner. Smart Card readedinterface. Expansion I/O. General graphics and audio. Sophisticated input devices (e.g. joystick). Sophisticated outpu
34、t devices (e.g. VCR, home control, video game console, etc.). ATM termination (if ATM is provided via the AN up to the STB). Graphics adaptation. ATM adaptation for signalling and video services. UNI interface (UNI or a limited subset). 22 Recommendation 1.375.2 (06/98) ieries A ;enes B Series C ser
35、ies D Series E series F Series G Series H Series I Series J Series K Series L Series M Series N Series O Series P Series Q Series R Series S Series T Series U Series V Series X Series Y Series Z ITU-T RECOMMENDATIONS SERIES Organization of the work of the ITU-T Means of expression: definitions, symb
36、ols, classification General telecommunication statistics General tariff principles Overall network operation, telephone service, service operation and human factors Non-telephone telecommunication services Transmission systems and media, digital systems and networks Audiovisual and multimedia system
37、s Integrated services digital network Transmission of television, sound programme and other multimedia signals Protection against interference Construction, installation and protection of cables and other elements of outside plant TMN and network maintenance: international transmission systems, tele
38、phone circuits, telegraphy, facsimile and leased circuits Maintenance: international sound programme and television transmission circuits Specifications of measuring equipment Telephone transmission quality, telephone installations, local line networks Switching and signalling Telegraph transmission Telegraph services terminal equipment Terminals for telematic services Telegraph switching Data communication over the telephone network Data networks and open system communications Global information infrastructure Programming languages Printed in Switzerland Geneva, 1998
