Getting IP television (IPTV) signals to the consumer's television in the home can be one of the largest difficulties faced by IPTV service providers. In the early years of TV, a simple cable was installed from the rooftop antenna to the one TV in the household. TV became more popular and multi-TV homes became the norm; homes built in the past 50 years have coaxial networks at multiple locations in the home. As cable TV has replaced rooftop antennas, premise distribution hasn't changed much because cable TV and off-air signals are nearly identical. Even digital cable TV signals are compatible with existing in-home coaxial networks, a design feature that is a testament to the value of a ready-to-use premise distribution network (PDN). Today most homeowners give no more thought to having TV service in every room than electricity, heating or any other necessary utility.

IPTV service providers face a new challenge, because their television signals are not natively compatible with in-home coaxial or telephone line networks. IP services are carried to the home over a wide area network or WAN (e.g. xDSL, fiber to the premise or wireless) and then converted to a different network technology for distribution within the residence. There are a few differences between PDN and WAN technologies. In general, WANs are "carrier grade" networks designed for public network service providers, whereas PDNs are "consumer grade" and only appropriate for networking within a single residence. Some characteristics that distinguish WANs include:

§ High powered amplifiers and precision receivers suitable for wide area distribution and reception
§ Good immunity from noise and impairments common in wide area networks
§ Remote provisioning features that enable service providers to add or remove features on a customer-by-customer basis using automated systems
§ Security features designed to protect against malicious and accidental interference that might affect other customers on the same network
Meanwhile, PDNs are more suitable for consumer networks and have the following characteristics:
§ Components optimized for high-volume, low-cost deployments
§ Relatively simple to setup and configure without extensive technical skills and training
§ Suitable for networking within the home, e.g. to share a personal video recorder from room-to-room or to share audio and video assets on a PC for viewing on a TV

For more reasons than IPTV, IP has emerged as an essential service that mandates a premise distribution architecture.

Requirements for PDN

There is general consensus that installing new Ethernet wiring is not a viable answer to the premise distribution requirements of IPTV and other innovative IP services. Whatever technology is adopted must meet basic conditions:

§ No new wires or cables
§ Global applicability
§ At least 100Mb/s available bandwidth
§ Enables any-to-any connectivity within a residence
§ Provides guaranteed quality of service

These requirements have spawned a new generation of PDN technologies. Home networking has become a multi-billion dollar industry in recent years as more and more IP devices provide entertainment, information and education. 

Candidate PDN Technologies

There are several existing and emerging technologies that are contending to become the IPTV premise distribution network of choice. It's not clear that a single winner will emerge. Cable, satellite and telephone network service providers could make different selections based on their specific requirements. It's also likely that different regions will endorse different technologies. Finally, many of these technologies are still under development and questions remain about actual performance in real homes.

Analog television is the most prevalent form of television signal distribution worldwide for cable and terrestrial broadcasting. It is a low-cost, well-proven and widely available technology that is suitable for both wide area and premise distribution that dates back to the 1950's. To utilize analog TV distribution for IPTV requires a home video gateway that accepts IP signals and converts the digital TV signal to analog. Once a digital IPTV signal has been converted to analog it is possible to transmit the analog signal over the in-home coaxial network and to receive the analog signal with a standard television tuner. Analog television distribution has the lowest cost of any distribution technology because it reuses existing coaxial wiring and doesn't require a set-top box at each viewing location. The primary disadvantage is that analog signals tend to be lower quality than digital signals and doesn't support HDTV, except at the primary viewing location. Still, roughly 75% of the television viewed in North America is analog television and it is very popular and cost effective.

Ethernet is the most prevalent IP network technology in use today. It operates over Category 5 (or better) wiring, which is widely available in office buildings but very few homes have Category 5 wiring. There are cost, complexity and cosmetic reasons that new wiring is not a viable alternative for existing homes.

DOCSIS (Data Over Cable Service Interface Specification) and its European analogue, EuroDOCSIS, are more commonly referred to as "cable modem." DOCSIS is a two-way digital technology for IP transmission that was designed for wide area networking. A typical cable modem termination system (CMTS) serves thousands of subscribers over distances ranging many miles. Although not strictly a PDN technology, DOCSIS, especially the forthcoming version 3.0, is suitable for IPTV delivery from a service provider directly to an end customer's set-top box or PC. However, several features that make DOCSIS appropriate for wide area service delivery also make it too costly to be a viable PDN technology for a single residence.

Multimedia over Coax Alliance (MoCA) is an industry standard for IP over existing coaxial networks. It meets all the major criteria for a PDN, including room-to-room connectivity. One of the advantages MoCA offers is a frequency agile bandplan, which means that MoCA can be configured to use frequencies that don't interfere with other services on the network. For example, several cable TV operators have endorsed MoCA in part because it can coexist with DOCSIS over in-home coaxial networks. Presently the MoCA standard is based on technology implemented by Entropic Communications, but the stated objective of the organization is to enable a licensing model for silicon manufacturers. Expect to see MoCA deployments in 2006.

Home Phoneline Networking Alliance (HPNA) began as an industry standard body in 1998 for data communication over phonelines.

Releases 1.0 and 2.0 of the specification provided 1 Mb/s and 10 Mb/s respectively. Release 3.0, which was ratified in June 2003, significantly enhanced the specification and made it a viable candidate for IPTV distribution:

§ Increased bandwidth from 10 Mb/s to over 100 Mb/s
§ Defined quality of service features and control
§ Added support for operation over coax as well as phonelines

In addition, the ITU-T formally adopted HPNA 3.0 as Recommendation G.9891 making HPNA 3.0 and attractive choice for telephone companies worldwide. The ability to operate over both coaxial and phoneline networks has broader applicability on a global basis as many countries do not have extensive in-home coaxial networks. HPNA is an open standard, meaning that silicon vendors are able to develop products to the HPNA specifications through the Alliance's adopter program. Deployments of HPNA 3.0 technology started in 2005.

HomePlug Powerline Alliance (HomePlug) is an industry alliance that has developed a standard for IP connectivity over powerlines. This has obvious appeal, as powerlines are even more ubiquitous and global than phonelines or coax. By definition, there is always a power outlet where a TV is located whereas it's less certain that either a coax or phoneline outlet is near the ideal TV location. HomePlug 1.0 was a baseline standard for 10 Mb/s IP connectivity that was adopted in 2002 and has been available in products since for several years. In August 2005 the HomePlug Alliance approved and released the HomePlug AV standard, which added quality of service features and support for speeds in excess of 100 Mb/s. Deployments for HomePlug AV are anticipated to begin in 2006.

Figure 1

Figure 2, Premises Distribution Matrix

Wireless technologies have great appeal for reasons of convenience, but wireless technologies to date have lacked the bandwidth, quality of service and robustness to support IPTV services. There is a considerable amount of activity by standards bodies and individual companies to remedy these shortcomings. The IEEE body, which ratifies and publishes the 802.11 series of recommendations, is developing the 802.11n standard to address the needs of IPTV services. The 802.11n specification will offer over 500 Mb/s of bandwidth and will utilize some advanced antenna technology to support quality of service requirements. The 802.11n standard will utilize spectrum that is compatible with worldwide frequency allocations. However, the 802.11n is not expected to be ratified until late 2006 with products to follow thereafter. Other companies have demonstrated success using so-called intelligent antenna technologies to improve performance of existing wireless standards. These efforts have yielded results on the order of 20-30 Mb/s in many circumstances, which is enough bandwidth for multi-channel IPTV service.

Summary

Home networking is an active area of new technology development today. It is generally agreed that any new PDN will support IP and will not require new wiring in the home. Phonelines, powerlines, coax and wireless are all candidate networks. Some, but perhaps not all, of these technologies will gain critical mass and become widely deployed. It's possible that telephone, cable and satellite TV providers will chose different PDN technologies. It's also quite possible that regional differences will

have an impact on the adoption of different technologies. For example, countries that don't have extensive existing in-home coax infrastructure won't select a coax technology. It could be that a mixture of technologies, even within one service provider in one region, will be adopted. For example, a service provider might select an inexpensive wireline solution as their standard deployment architecture, then selectively deploy wireless for customers that want mobility. Whatever ultimately plays out one is for certain that there will be a lot of interest and competition in home networking for years to come.

Mark Evensen, Co-founder and VP of Product Development Evensen has been designing and deploying video solutions for over 15 years. He was the architect of the world's first video over DSL deployment and knows intimately what it means to design and develop an end-to-end telco video architecture from the ground up. 

Entone Technologies
1840 Gateway Drive, Suite 200
San Mateo, CA 94404
Phone: (650) 378-1215
Fax: (650) 240-0135