Hybrid fiber/coaxial cable has emerged as the leading video distribution technology. It promises to remain essential as companies expand their service offerings.
Bob Jordan and Debbie O`Meara, Ortel Corp.
Ten years ago, the first public demonstration of linear fiber optics for cable TV at the Western Cable Show quickly revolutionized the industry. Looking forward, that same technology may revolutionize the next 10 years as well, not just in television but in other ways that affect homes and workplaces.
Since that first demonstration, hybrid fiber/coaxial-cable (hfc) networks have emerged as the leading video distribution technology, providing dramatic improvements in picture quality and reliability. With each improvement in linear lasers and their associated radio-frequency circuitry, power output, bandwidth, and ultimately channel capacity increased. hfc systems based on 1550-nanometer transmission, along with Synchronous Optical Network and digital multiplexing alternatives, enabled supertrunking and the consolidation of headends. Return-path laser transmitters and cable modems have more recently added interactivity. Today, a two-way 750- or 860-megahertz system and 1000-home nodes are prerequisites for service deployment.
hfc has proved the most reliable and cost-effective broadcast technology for network operators worldwide, enabling them to satisfy the nearly insatiable demand for entertainment, cultural, and government programming created by over one billion television households around the globe. Alternative delivery mechanisms such as broadcast satellite, wireless cable, and radio-based systems complement but do not replace it, since hfc is the only one of these that is independent of the local terrain and weather anomalies that affect line-of-sight or satellite systems (although it does require right-of-way for fiber deployment).
North America is perhaps the most advanced in its deployment, with nearly half of the market served by newly upgraded cable systems. In Western Europe, some markets, such as Belgium and The Netherlands, are almost entirely covered by cable; others, including Italy, Spain, and Portugal, are just beginning to build. The less-developed Eastern European countries, as their economies privatize and funds become available for communications infrastructure, are simply bypassing the older technologies and installing modern hfc plant. The massive Asian market, with three times as many television households as Europe, is also in the early stages of developing the networks needed to meet its growing demand for cable TV. By the year 2005, nearly one-third of these households will be passed by cable.
More than video
hfc, especially with an activated return path, lends itself to more than television. Internet users will benefit from the added bandwidth as today`s 28.8-kilobit-per-second modems are replaced with Ethernet speeds of up to 10 megabits per second, similar to what is available in ordinary local area networks. Typically, once users gain access to higher data rates, the backbone speed must increase, which spurs yet another round of increases in access speeds. hfc is the architecture that can accommodate this demand.
As video streaming, low latency connections, Internet protocol (IP) communications, and other advances pioneered by the data-communications industry follow, personal computing and cable TV will begin to converge in ways that are not yet fully understood. At home, the combination of IP-enabled services and video-on-demand will yield a high capacity, online system for data, video, and communications. At work, the extension of hfc to business parks and metropolitan centers will readily expand the reach of this system to include small office/home office users, hospitals, educational institutions, finance centers, and major businesses.
Trend watch
Will the prospect of combining a cost-effective delivery technology with IP-enabled data and video services produce explosive growth for the industry? The first indicator will be the take rates for cable modems and cable telephony in trial areas. Another will be the "churn"--customers who sign up and later discontinue--and lack of it. In Europe, for example, cable modem users do not want to give up the service, not so much for the connection speed as for the fact that cable connections are always on, so users avoid local calling charges. Finally, it is not necessary to have an obvious "killer" application to drive rapid growth. The Internet itself grew rapidly from two very unexpected sources: navigation browsers and chat rooms.
Much as cable bandwidth opens up Internet access, digital broadcasting opens up the return path. When local station channel numbers are no longer tied to a particular frequency in the hfc spectrum, the return path will be expandable beyond its current narrow confines. This is especially critical to the development of symmetrical applications such as file transfers or video streaming in both forward and reverse paths. Once the connection enables such activity, Internet commerce will potentially move beyond simple catalog shopping and enable collaborative work between geographically separate people or groups.
hfc networks may incorporate other technologies as well. For example, telephony at 1550 nm and television at 1310 nm may be deployed on a single fiber. This technology is particularly desirable in countries with limited fiber or limited capital to deploy it, because it upgrades both networks with a single construction program. And, as fiber moves deeper into a coaxial-cable network, passive optical networks may emerge to handle high-speed data applications. Finally, by combining cable microcell integrators/headend interface converters and dark fiber from the hfc plant, a network operator can use working plant to deliver personal communication services (pcs) signals, thus becoming a cellular provider and capturing a share of the growing pcs market. These possibilities are well-known and some trials are under way.
How will these changes affect network operators? As they increase their options, they will need to re-examine their business models. While they will retain some basic elements, such as pricing for entertainment services on a tiered basis, customer service operations, and billing, they will also need to incorporate practices common to telecommunications companies. Proactive network management, including data link monitoring, is one likely consideration; capacity planning, including headend servers, switches, and routers for the data traffic, is another. Operators may even choose to become Internet service providers and wired or wireless communication companies in addition to their conducting their current business. This will require them to also manage advertising, subscription, and service revenue streams.
What happens next? Cable operators must continue to build or rebuild their modern hfc plant to accommodate the new offerings. This plant will include more highly linear 1310-nm lasers, for higher analog channel capacity as well as digital broadcasting. Operators will also choose lasers with higher output power, as high as 16 milliwatts and above, to generate the signal strength to span greater distances. And as they extend into the most demanding locations--many parts of Asia, for example--they will use more 1550-nm distribution systems, the most cost-effective option for both high-density urban areas and far-flung remote towns.
Looking back, hfc dramatically changed the cable-TV industry in the past decade and now provides a worldwide technical base on which new services can be layered. Looking forward, the convergence of video and IP-enabled data services on hfc networks can revolutionize the next 10 years as well. Explosive growth may follow as cable modems open the Internet with higher access speeds, and digital broadcasting leads to new applications. New business models and alliances will enable the network operators and their customers to realize the potential of hfc networks. q
Bob Jordan is vice president and business manager for Ortel Corp.`s broadband communications business sector (Alhambra, CA). Debbie O`Meara is product marketing specialist at Ortel.
This report first appeared in the November 1997 issue of Lightwave magazine, another PennWell publication.