IPTV, a system based on broadband networks, offers colorful multimedia video services to different user terminals such as TV, PC and mobile phones. It is not only an efficient platform for the telecom operators to deliver triple-play services (i.e., telecom, cable TV and Internet), but it also gives the operators the best opportunity to transform themselves into comprehensive information providers. As a result, it has a promising prospect. The types of services the IPTV system offers are diverse, and they include video, telecommunication, information and entertainment. As to the forms of the services, there are live broadcast, video on demand (VOD), time-shifted TV, record & broadcast, karaoke, video communication, information service, finance and securities, interactive TV, e-commerce, distant learning, and so much more. These new, broadband-based entertainment value-added services have a great number of prospective users.
The development of IPTV system is closely tied to network technologies, including video coding/decoding, digital rights management (DRM), video distribution network (VDN), electronic program guide (EPG), stream media, and multicast. A complete end-to-end IPTV solution is made up of the headend encoding system, the content/service operation and support system, the terminal system (mainly set-top box, or STB), the distributed streaming service system, the content processing system, DRM, the comprehensive service management platform, EPG system, the value-added system and the broadband network equipment. So far, it is one of the solutions that cover the widest range of contents.
ZTE AVS-based IPTV Solution
The coding/decoding technologies used in IPTV are mainly Moving Picture Experts Group (MPEG)-2, MPEG-4, H.264 and AVS (Audio Video Coding Standard). Among them, AVS is a homegrown intellectual property in China, and has become a standard of International Standard Organization (ISO). The successful application of AVS-based IPTV solution is no doubt of great help to promote the healthy development of IPTV industry in China.
Headend encoding system: AVS encoder
The devices in the headend system are mainly AVS encoders, which falls into two kinds: real-time encoder and offline encoder.
Real-time encoder: It encodes the video signals of the live-broadcast channel into AVS coding format in real time, and converts them into digital audio/video IP packets before transmitting them to the user for play. In current IPTV operation mode in China, the AVS program sources are directly provided by the content providers (e.g., China Central Television, Shanghai Media Group).
Offline encoder: It encodes VOD programs into AVS format in advance, and stores them into the VOD server for the user to play as required.
The service system, consisting of content operation platform, service operation platform and VDN distribution platform, publishes, manages, categorizes and distributes the AVS-coded contents.
The content and service operation platforms are basically for the AVS content providers and the IPTV service operators. They provide interfaces for IPTV users, content and services; manage EPG; and perform functions like authentication, authorization and billing. By interconnecting with Operations Support System/Business Support System (OSS/BSS), they control the operation of IPTV services.
The AVS-based IPTV service operation platform is divided into two parts.
The first one provides the following modules or functions: CP/SP access interface, user equipment management, content management, service development and management, interconnection with OSS/BSS. With the CP/SP access interface, the operator can easily introduce and manage several AVS content providers. The content management module provides content source-related information to achieve a unified management of the contents. The service development and management module provides an interface for developing and introducing multiple services at any time and at any place.
The second part provides interfaces for accessing the service operation systems of several manufacturers, allowing the IPTV operator to introduce and effectively manage other system solution providers.
Service network: VDN
Unlike other data services, the IPTV system occupies more network bandwidth, demands a higher network quality, and uses different sorts of stream media files. To ensure the service quality and offer users with better experience, a good solution currently is to widely use VDN stream media file distribution technology. The basic principle of the service network (i.e., VDN in the VAS-based IPTV solution) is as follows: it transmits service contents such as video/audio programs to the edge nodes with VDN technology to serve the users nearby; thus, the service quality is efficiently improved and the transmission pressure on the backbone network is reduced. Moreover, by flexibly configuring the video servers at the network edges, the network can be easily shrunk or expanded. The core technology used in the service network is the content and service distribution mechanism. The VDN service network makes the most important part of the IPTV solution, and it consists of distributed streaming system and service distribution and dispatch strategies.
The distributed streaming system is further divided into two subsystems: content distribution and media service.
- The functions of the content distribution subsystem include AVS content management and buffering, service management, billing, resource reporting, alarm and configuration. Connected to the service system, the subsystem receives the configuration instruction from the service system and distributes AVS audio/video contents accordingly.
- The media service subsystem provides the AVS-coded media services such as VOD, live broadcast, carousel, and time-shifted TV.
The bearer network is always constructed on the basis of a broadband network (e.g., backbone network, convergence network and access network). If the AVS-based IPTV solution is to offer services on a large scale, the following have to be taken into account to enable the bearer network to support IPTV services:
- Quality of Service (QoS) guarantee: low packet loss rate, short latency and small jitter; prioritization of different services; enough bandwidth
- Multicast capacity: compatibility with multicast protocol, multicast control management; quick switch of channels; forwarding capability
- Security: content sources' validity and transmission security; user and service provider management; video service isolation
- Reliability: reliable connection to the program source, and network reliability
The home network provides comprehensive information services, enabling modern families to communicate in various ways. With such value-added services as voice, broadband and data bound, the home networking scheme can meet the demands of modern families for voice, Internet and video services.
In the IPTV solution, the main equipment for the home network is the STB. The STB is a terminal installed in the user's home. It accesses the service network via ADSL or LAN line and connects the TV at the user end. With standardized universal input/output interfaces, STB functions to forward the information from both the network and the user, and convert the media format for playing in the display screen.
Recently, owing to its technically advanced solution and powerful service capability, ZTE defeated many competitors from all over the world, and solely won the world's first AVS-IPTV commercial network development bid, the Dalian IPTV project. This success witnessed the strength of ZTE in multimedia IPTV market, marking ZTE's continuous leading position in AVS-based network video and communication solution, following MPEG-4 and H.264. The commercialization of Dalian IPTV project will greatly promote the industrialization of AVS standard, and it is a victory for the Chinese information technology industry in breaking the monopoly of foreign technologies and sticking to the policy of "independent innovation".