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----From IPTV in China to an overview of network developments

By Qian Hao

What inspiration have we drawn from the market development and construction mode of IPTV in China? How can we understand the emerging technologies and development trends in regards to the IPTV bearer networks? What elements should carriers consider when analyzing architectures and strategies, while constructing and operating IPTV networks? These are but a few of the questions this brief article will attempt to address.

IPTV Service to Hit the Market

According to a recent report from Infonetics, the global IPTV equipment sales revenue topped US$400 million in 2005, and over the next 3 years global IPTV equipment and service income is expected to reach US$44 billion (US$6 billion from IPTV equipment, and US$38 billion from IPTV services). In 2009, the number of global IPTV subscribers is expected to reach 53 million, with 4.9 million in China, which forms the largest IPTV market in the world.

The China IPTV 2006-2010 Market Forecast and Analysis conducted by IDC, says that more than 400 million TV users in China are viewed as fertile soil by the IPTV industry. It is estimated that urban users in China spend about 181 minutes a day on average watching various TV programs, and the 2008 Olympic Games, which will be held in China, is expected to strongly boost the development of China's IPTV.

As early as 1999, Microsoft put forward its "Venus Plan" in China, and its success depended largely on the development of Internet in China. This plan, however, ended in failure due to constraints in network infrastructure and costs. Since 2003, the global IPTV market has been rapidly developing. For instance, in Europe, FastWeb, an Italian broadband service provider, was extremely successful in 2004 in developing IPTV subscribers and increasing ARPU. Among its broadband subscribers, 36% represented IPTV subscribers and the company's ARPU reached 911 Euros. Similarly, in the United States, Verizon was able to attract more than 1 million IPTV subscribers by the end of 2004, and SBC and Microsoft joined forces in an IPTV cooperation agreement which is estimated to be worth as much as US$400 million over the next 10 years. In Asia, PCCW launched its NOW-TV service in August 2003, and now the service is providing broadband TV channels to more than 600 thousand customers.

In 2005, almost all carriers worldwide included the Triple-play service in their company portfolio plans and began testing on various IPTV service. In China, thanks to media promotions, IPTV has become one of the hottest and most controversial topics and it is currently going through a process of tests, standardization, trial use, and commercial use.


A Rich Diversity in Networking

In China, many local carriers have made various attempts at deploying IPTV services, which has resulted in the following representative modes:

Hangzhou Mode: This was the first attempt at IPTV network construction. Two of its most striking features are digital TV reconstruction and IPTV terminal integration. Each multi-mode STB (Set Top Box) offers two wires (HFC & LAN). For instance, if a subscriber has no access to the broadband network, then the carrier can lay a free broadband line in the subscriber's home that will enable him or her to have interactive VOD services. However, he or she will not be able to log onto the Internet using this broadband line. This mode avoids bi-directional reconstructions in the HFC network and enables the integration and complementation of IPTV and digital TV resources.

Harbin Mode: The mode was introduced by China Netcom's subsidiary in Harbin in late 2004. It was designed to construct an IP MAN with high QoS and reliability that is able to bear IPTV services. At first, the network adopted the BRAS duplication method to enable BTV services. However, STBs were required to pass the PPPoE access authentication to share the access network, and so by using the Harbin mode one can avoid difficulties when reconstructing the existing MAN. Later on, reconstructions were made in the access network, and the control points and duplications points for multicast were moved downward. The network currently supports over 50 thousand subscribers.

Shanghai Mode: The serial modes can be further categorized into Daning Mode, Gubei Mode and Pudong Mode. These modes offer broadband access via FTTH+LAN solution or EPON, or simply by upgrading DSLAM to ADSL2+. Duplications can be enabled in various ways, for example BRAS multicast and DSLAM multicast.

Jiangsu Mode: This mode enables SR to implement multi-edge network service control via the DHCP and access authentication. By way of flexible QinQ, switches at the access convergence layer can separate services from physical links and realize DSLAM multicast control and duplication. Existing Internet services share the IP MAN via PPPoE authentication and BRAS bearing. STBs of the IPTV network retrieves dedicated IP addresses and are charged or managed via DHCP Option 82 location, and the DHCP Policy Server.

Guangdong Mode: This mode combines IP MAN reconstruction and transmission network resources to bear IPTV services. BRAS duplication method was adopted in early test phase. Later on, the access network was gradually reconstructed, and the ATM DSLAM was upgraded to the IP DSLAM. STB encapsulates and transmits single multicast services using dual protocol stacks. Multicast duplication points and control points are located in the DSLAM and network switches. In places not supporting multicast, the multicast switches based on subscriber VLAN duplication are adopted. Network switches at the access convergence layer enable service isolation via a flexible QinQ.

Thus far, China Telecom has decided to implement IPTV trials in 21 metropolises throughout China, including Guangzhou, Shenzhen, Shanghai, Hangzhou, Nanjing, Suzhou, Xi'an, Chengdu, and Fuzhou. Shanghai will run commercially in Sep. 2006. China Netcom is also going to implement IPTV trials in 21 metropolises, and the first trail of Harbin was put into commercial run now, other trails including Beijing, Tianjin, Ji'nan, Qingdao, Changchun, Taiyuan, Shenyang, Dalian, Shijiazhuang, Zhengzhou, and Hohhot. At present, IPTV operation modes are still in the development phase. China Central TV (CCTV) recently received the second IPTV license in China, following the Shanghai Media Group, meaning more opportunities for broader cooperation and operations for carriers.


IPTV Bearer Technologies are Changing the Industry

As a support to service systems, a bearer network is responsible for terminal user access and network layer authentication. Based on upper-layer requirements, it guides each service information flow from the source end, to the destination end, and according to the specific attributes of each service, it dispatches network resources, to ensure service functions and performance. It also realizes the special requirements of streaming services on the communication layer, e.g. multicast support.

While many people are still concerned about the supplier for each service system or STB, several major carriers have completed bearer network standardization, testing and scheme authentication. With the constructions, or reconstructions of backbone networks, (e.g. MAN and AN), carriers are able to support the deployment of IPTV services. Based on mature technologies and rich experiences bearer networks offer higher QoS, reliability, and security, in order to meet the requirements for bearing Triple-play services.

In Harbin Mode, a second IP MAN was constructed in the bearer network and the access network was reconstructed and shared, so that now the network is able to bear multiple types of services. The fast user base growth confirmed the success of Harbin mode. Shanghai Mode and Hangzhou Mode have blazed a path for the emergence of many new technologies, including PON integrated access, multi-mode STB, and FTTH. Moreover, fast speed and stability have become basic elements for ensuring more enjoyable customer IPTV experiences. Guangdong Mode has made full use of existing resources in the existing network to enable the smooth evolution from the ATM network, to the IP network. Consistent with IPTN, it adopts PPPoE authentication, and dual-protocol-stack STB, and is responsible for adding many new features to the contents of the IPTV network. Jiangsu Mode features the integration of DHCP authentication and multi-edge network bearing, making the network more operable and manageable.

The development of IPTV in China now faces great risks, as well as golden opportunities. Constructions of IPTV bearer networks can lay a foundation stone for future development. This is an ideal way of how data communication networks can support new service applications.


Network Development Aims High

At present, IPTV development in China is largely focused on policies and the industrial chain. So far, policies have been less restrictive, while each party of the industrial chain is becoming more and more clear about its roles and positions. The technical element has matured to a point where it is no longer a major risk in network constructions. The maturity of several technologies are discussed and briefly summarized below.

• Telecom networks become IP networks
  
  To further reduce costs in network constructions, operations and maintenance, the prevailing idea in network constructions for telecom carriers is to construct IP networks. Traditional telecom services have been gradually shifting from the original ATM architecture to the IP architecture. IPTV represents a new application in IP networks, and only IP networks can enable interaction ability, which distinguishes IPTV services from traditional TV services. 
  
  
• Traditional IP networks become telecom networks
  
  Traditional IP networks were first constructed on the basis of Internet ideas and lacked complete QoS and reliability guarantee, as in ATM networks. Network security was also a headache for carriers. However, in recent years the integration of new services, for example, VoIP, 3G and IPTV, has placed higher requirements on telecom networks in regards to high reliability, QoS and security. To provide operable and manageable services and realize Triple-play services, all carriers have been dedicated to reasonable network resources planning and hierarchical deployment of QoS and security strategies, in order to guarantee 50 ms switchover duration, and 99.999% faultless operations. Such efforts have laid a solid foundation for enjoyable customer experiences from IPTV services. 
  
  
• From service integration to network integration
  
  The development of IPTV services involves various integrations. First, is the integration of service modes. Carriers from China Broadcast & TV has been closely cooperating with fixed network carriers in a mutually beneficial mode. Such cooperation agreements have greatly helped to boost the healthy development of the industrial chain. In terms of technologies, IPTV networks will see a gradual integration of fixed and mobile technologies. This will certainly enrich the services in the networks. PPPoE authentication and DHCP access authentication modes are also integrated, which helps to protect carriers' benefits. In terms of network development, although many private networks and different services are running in parallel, since the introduction of MSE (Multi-Service Edge) equipment, which integrates many technologies such as, BRAS, SR, SBC, IPS and Firewall. It also requires high service sensitivity and cooperation. Single-edge networks can offer high reliability, QoS and security and have now become the first choice among carriers. In terms of research on standards, IPTV has been included as an integral part of NGN services. 
  
  
• Diversified access technologies
  
  A core network can bear multiple services. The access network will see a considerable amount of diversification, with many access technologies playing different roles. The requirement for increased bandwidth from IPTV services has stimulated the development of new technologies. For instance, ADSL has been gradually updated to ADSL2+, and more subscribers are accessed via FTTx + LAN mode. According to incomplete statistics, FTTx + LAN has been used in more than 30% of all service accesses. EPON and GPON technologies have also shown considerable strength in the market. Wireless development represented by WiMAX, has recently become the focal point of much research and testing. Access network is no longer a single network, it provides better service isolation and protection capabilities, by deploying flexible QinQ technology in access and convergence layers, and with the 802.1p, the network is able to isolate various services. The Ethernet RPR and RRPP technologies have also made full use of ring network technology and enable milliseconds protection, with low-cost constructions. New fault detection technologies such as, BFD, provide a basis for better and quicker switchover. MPLS is introduced to the access network, and with the cooperation of Ethernet OAM, provides a set of defect detection tools and correction mechanisms. The access network offers some features similar to those in traditional transmission networks. 
  
  
• IPTV becomes a part of NGN architecture
  
  More and more standardization organizations and carriers have recognized the close relationship between IPTV and NGN. Major features of NGN are: diversified services, open service interfaces, simpler management scheduling and maintenance, low maintenance costs, QoS guarantee, and high security and reliability. In service and control system, ITU-T categorizes services into four sub-types: IP media services (IMS), PSTN/ISDN simulation services, streaming services (SS), and other multimedia services (OMS). The streaming service is used to transmit and play continuous audio/video data streams in the Internet or Intranet, according to the time sequence. It features continuous, real-time and sequential data streams.
  
  IPTV services can be enabled via the telecom broadband network or mobile Internet, the bi-directional digital TV broadcast network of China Broadcast & TV, or the combination of both. Undoubtedly, the telecom broadband network, or mobile Internet, is a type of NGN network, and so is the digital TV broadcast network of China Broadcast & TV.
  
  NGN is able to provide overall services, which includes: voice, data, video, streaming, Internet access, TV broadcast and mobile services. Regardless of the bandwidth requirement, terminal type, fixed or mobile, each service can find a suitable service interface in NGN network. As a type of NGN service, IPTV caters to the development trends of NGN, and thus, is an important part of it.

IPTV today is no longer a luxury service confined in LANs or labs, but can enable large-scale deployment and operations. As network development continues to break new ground, and with the on-scale construction of NGN networks, IPTV are expected to serve more and more people, and change our lives.