Fiber-Based Broadband Access Technology and Deployment
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10 Fiber-based broadband access technology and deployment Richard E. Wagner Corning International, Corning, New York, USA Abstract After more than 20 years of research and development, a combination of technolo- gical, regulatory, and competitive forces are finally bringing fiber-based broadband access to commercial fruition. Three main approaches, hybrid fiber coax, fiber to the cabinet, and fiber to the home, are each vying for a leading position in the industry, and each has significant future potential to grow customers and increase bandwidth and associated service offerings. Further technical advances and cost reductions will be adopted, eventually bringing performance levels and bandwidth to Gb/s rates when user demand warrants while keeping service costs affordable. 10.1 INTRODUCTION The use of fiber-optic technology in telecommunications systems has grown over the past 25 years, since its introduction as a transmission media for linking metropolitan central offices in 1980. In the decade after that, long-distance networks deployed fiber-based systems extensively, followed by significant construction of metropolitan interoffice network infrastructure. During that time the reliability and availability of transport systems improved dramatically due largely to the low failure rates of the technology. As a result, researchers and developers dreamed of a time when fiber- optic technology could be economically applied in access networks [1] to replace the copper-based systems extending from central offices to residences and businesses (see Figure 10.1 for a diagram [2] of such scenarios). A perfect example of this visionary dream was articulated by Paul Shumate and Richard Snelling in an IEEE Communications Magazine article published in 1989 [3], where they predicted that a fiber-to-the-home (FTTH) solution could be at economic parity with copper-based solutions by 1995 if a carrier were to deploy 1–3 million lines (see Figure 10.2 for a replication of their prediction chart). They went on to explain that it could be possible Optical Fiber Telecommunications V B: Systems and Networks Copyright Ó 2008, Elsevier Inc. All rights reserved. ISBN: 978-0-12-374172-1 401 402 Richard E. Wagner To metro Serving office network Feeder Drop Distribution 0–1 km 15–20 km 1–50 Mb/s down 1–5 Mb/s up Services • Phone • Internet Cabinet • Cable TV Office equipment (signal split) Serving 1000–5000 subscribers Economics Approaches Subscribers • $1000 cost per subscriber • HFC • Residential • $100 per month revenue • FTTC/xDSL • Apartments • FTTH • Business Figure 10.1 FTTx access network reference models (this figure may be seen in color on the included CD-ROM). $4000 $3000 FTTH Most likely new line (copper distribution) FTTC $2000 Cost $1000 Life cycle cost savings Accelerate copper parity 1990 1995 2000 Figure 10.2 FTTH vs copper introduction cross-over date (C. 1991 Shumate). to convert the entire US network to FTTH over a 25-year period, producing a broadband network for the Information Age. They further noted that there were many details to be worked out, including standardization, network interfaces, power- ing at the customer end, video capability, and network evolution. This work was pioneering and prophetic, as we now know today. But what those authors, and others with them, did not foresee was the dramatic effect of the telecommunications consent decree on competition in the United States, the dampening effect of the federal communications commission (FCC) policy allowing competing carriers to lease infrastructure at cost or below, the 10. Fiber-based Broadband Access Technology and Deployment 403 12,000 10,000 dot.com Asian Flu 8000 Telecom Act 6000 review Triennial Cable Act 4000 Shipments 2000 13.1% / yr Growth Sales in $ millions/month 3.4% / yr Growth 0 Jan-01 Jan-05 Jan-07 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-02 Jan-03 Jan-04 Jan-06 Figure 10.3 Telecom bubble—telecom equipment shipped in the united states vs time (this figure may be seen in color on the included CD-ROM). delaying effect of the telecom “bubble” bursting [4] (Figure 10.3), and the bandwidth growth driver of the Internet when used for business and entertainment. Now, in Asia, North America, Europe, and globally, we are seeing significant capital spending on fiber-based broadband access infrastructure [5, 6]. Some of the earliest spending was in Japan, where government funding and initiatives helped to push carriers toward fiber-based access network technologies. Soon after, in the United States, spending was driven by three events: the FCC has made an historic policy decision in 2003 to free fiber-based solutions from competitive regulations, cable TV (CATV) operators have increased telecom- munications industry competition by offering high data rate Internet service and telephone service over the Internet, and users have grown accustomed to using the Internet for sharing large digital files containing e-mail messages, photos, music, video, and news clips. In response to these drivers, the three major local exchange carriers in the United States (Verizon, BellSouth, and SBC) issued a common request for information to broadband access system suppliers, trusting that the resulting volume manufacturing incentives would bring the cost of deploying such systems in line with associated service revenues. Now it appears that this risky move was justified, because in North America we have seen about 8 million fiber-based broadband access lines deployed to homes since then, with more than 1.5 million customers taking the services being offered. Globally there are, by the end of 2007, about 11 million fiber-based access customers. The overall result of this is lowered costs for the technology and its installation, significant technological advancements in the equipment and installation methods, and improved service offerings to customers at affordable rates. In alignment with this trend, European carriers are now committing funds to fiber-based access networks as well, and in a few years China will ramp up spending for this purpose. 404 Richard E. Wagner This chapter will focus on the fiber-based approaches to broadband access worldwide, including some of the drivers for deployment, the architectural options, the capital and operational costs, the technological advances, and the future potential of these systems. Three variants of fiber-based broadband access, collectively called FTTx (fiber to the x) in this chapter, have emerged as particu- larly important. They are hybrid-fiber-coax (HFC) systems, fiber-to-the-cabinet (FTTC) systems, and FTTH systems. 10.2 USER DEMOGRAPHICS One of the most dramatic and unexpected drivers for fiber-based broadband access has been the explosive growth of the internet and its associated applications. As early as April 1993, when the Mosaic browser became available, the public began to use the internet for transfer of text messages, photos, and data files. Building on that initial application, the number of Internet users has grown to 211 million in the United States alone, and represents about 70% of the population now, while globally there are about 1.2 billion internet user representing about 18% of the world population [7, 8] (Figure 10.4). Not only has the number of users grown, but individual usage has expanded exponentially, until today we routinely exchange music, photos, videos, and software files as large as 10’s of megabytes each. A close look at the bandwidth available to access the Internet shows that it was gated by the technology being offered [9–11] (Figure 10.5), with new ones adopted in cycles of roughly 5–6 years each [2] (Figure 10.6). For example, the earliest users bought phone modems, initially at 9.6 kb/s, then increasing in performance to 14.4 kb/s, 28 kb/s, and finally 56 kb/s [10]. Typically, a group of early users (indicated as Initial Users in Figure 10.6, representing the top 25% of users) adopt the new technology first; the mainstream follows, and finally everybody else (Slow Adopters in Figure 10.6, 100% Australia 90% Population Netherlands US 80% Korea 2006 Statistics World USA China Japan Japan 70% • People 6.6 B 301 M 1322 M 127 M Canada • Internet users 1.2 B 211 M144 M86 M 60% UK • Broadband 0.1 B57 M52 M26 M Germany 50% Italy France 40% 30% Internet users Mexico Brazil 20% Russia World 10% China 0% India 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 Figure 10.4 Internet usage worldwide (this figure may be seen in color on the included CD-ROM). 10. Fiber-based Broadband Access Technology and Deployment 405 250 FTTH Projected FTTC HFC aDSL 200 Fixed wireless Satelite ISDN 150 Modem (56K) Modem (33.6K) Modem (14.4K) 100 50 Internet users (millions) 0 2000 2001 2002 2003 2004 2005 2006 2010 2007 2008 2009 2011 2012 Figure 10.5 US residential access technology adoption over time (this figure may be seen in color on the included CD-ROM). Initial Users begin to adopt: 56 k modems DSL and cable modems FTTx 100 26 Mb/s FTTH Top 10% 10 1.0 Mb/s FTTC 1 Initial 56 kb/s Cable modems Users and DSL 0.1 Main stream 0.01 Dial-up modems Slow Adopters Average bandwidth (Mb/s per user) 0.001 ’94 ’95 ’96’97 ’98 ’99 ’00 ’01 ’02 ’03 ’04 ’05 ’06 ’07 ’08 ’09 ’10 Figure 10.6 US user downstream connection speed trend and projection over time (this figure may be seen in color on the included CD-ROM). representing the bottom 25% of users) takes advantage of the technology. While the entire adoption cycle takes 8–10 years from introduction to 50% adoption, newer technology is introduced before even half of the users have the old in place.