From almost the dawn of the Internet, phone and cable companies have been fighting for the hearts and minds of the savvier consumers all over the world. The key battleground is the so-called last-mile link to the home or business, where the phone companies have been pitting their digital subscriber lines (DSLs) against the cable providers' cable modems. In most places in the world, DSLs have been the more popular option, though in the United States, with its very large cable infrastructure, cable modems have had a distinct edge.
All along, however, the Holy Grail has been fiber to the curb--an all-optical link going right into homes or businesses and providing bandwidth and speed that just can't be beat. Now, three of the four U.S. regional Bell operating companies (RBOCs, or Baby Bells)--Verizon, BellSouth, and SBC--intend to start building such fiber-optic networks to the premises as early as the first quarter of 2004. Of the three companies, Verizon Communications Inc. (New York City) has by far the most ambitious plans: it says it intends to provide every home and business it serves with a fiber-optic connection during the next 10-15 years, at an estimated total cost of as much as US $40 billion.
”Customers' bandwidth appetite is constantly increasing, and this deployment will let us get out in front of that,” says Greg Evans, vice president of services and access technologies for Verizon in Arlington, Va.
In May, Verizon, BellSouth, and SBC got together and agreed on a common set of specifications for fiber to the curb. At this writing, they are considering responses from vendors to their requests for proposed equipment built to those specs.
Fiber to the curb can provide bit rates of almost 20 Mb/s--or roughly 40 times the rates typical with a cable modem. It's always been obvious that fiber-to-the-curb networks would be the most direct means of giving homes and businesses all the bandwidth they could possibly want, as really high-speed file sharing, videoconferencing, video-on-demand, and sundry other high-speed services become ubiquitous. So why are the phone companies getting set to offer it only now?
It may be partly the ruling by the U.S. Federal Communications Commission (FCC, Washington, D.C.), in February, that the RBOCs need not share new equipment installed to support broadband traffic, though they say they're still awaiting clear guidelines from the FCC in this area [see ”Share and Share Not,” IEEE Spectrum, April, pp. 19-21]. Then, too, there's the fact that the regional companies emerged from the telecom meltdown relatively unscathed, with huge and virtually guaranteed cash flows--in the case of Verizon, about $22 billion a year, at present.
With the companies set to spend big money, the specifications agreement reached this spring should help entice vendors to enter the alluring market for fiber-to-the-curb equipment. Traditionally, though all telecom equipment has been built to common standards, each service provider has set different specifications for particular applications, like fiber to the curb.
As a result, vendors have had to modify products to suit each big customer, making it harder and more expensive to sell in volume. The new common technical requirements for fiber-to-the-curb networks ”help the vendors build products we can all use,” observes Jim Jackson, BellSouth research director for technology, planning, and deployment in Atlanta. ”This gives vendors scale and volume.”
Passive optical networks
The type of optical to-the-curb networks the three carriers will each be building will be passive, meaning they use no power between the provider's central office and the customer, and require no active electrical devices, like amplifiers. One fiber, about the length of today's copper loops, will serve as many as 32 customers [see diagram].
The three main elements in the networks will be an optical line terminal at the central office, connecting the subscriber's local loop to the network; a splitter, which divides the single line into a number of equal channels, encrypted for each customer; and a terminal unit in the home or business that picks out the customer's signal and decrypts it (or, alternatively, encrypts an outgoing signal). The agreement signed by the three companies focuses on the electronic elements, specifically the line and customer terminals.
Take SBC's passive network. ”One fiber leaves the central office, encounters one or more optical splitters, and from there, the fiber fans out to 32 locations,” explains Ralph Ballart, vice president of broadband infrastructure and services at SBC Labs (Pleasanton, Calif.). Going in the other direction, when 32 outgoing signals reach the central office headed for the backbone network, ”we use a time-based multiplexing method to recombine them so they don't interfere with each other.”
Leaving the phone company office, bandwidth in the passive networks ranges from 155 Mb/s to 622 Mb/s. The bandwidth that customers end up with depends on the number of splits between them and the central office. For SBC, with 622 Mb/s at the central office and 32 customers per fiber, the average will be 19.5 Mb/s. The network, however, will be ”dynamic”--that is, at midnight, if no one else is on the network, you will get a blazingly fast connection.
A shot in the arm for telecom?
Plans to build fiber-to-curb networks are good news for telecom vendors, still suffering from the 2000 technology crash. ”We definitely believe there is a market for fiber to the premises, and we plan to aggressively go after that business,” says Bob Laurent, product marketing manager for Fujitsu Network Communications Inc., in Richardson, Texas. The attitude is essentially the same at Lucent, says Donald Crowe, director of product development at Lucent Technologies Access Networks Group (Whippany, N.J.).
Of course, the new networks are in principle a threat to entrenched cable interests, as well as to the DSL investment the phone companies have made themselves. So far, if providers of cable modems and DSLs are nervous, they aren't admitting it. ”Having invested $75 billion since 1996 to upgrade our networks, the cable industry is very well positioned in serving our customers with respect to any competition,” says Paul Rodriguez, a spokesman for the National Cable and Telecommunications Association (Washington, D.C.).
SBC's Ballart believes that all-fiber local loops initially will be built at new residential developments with no copper network in place and at apartment houses with a high density of homes. New businesses in growing areas also will be good candidates. BellSouth's Jackson agrees: ”Replacing existing copper networks could take seven to 10 or even more years.”
Since the construction of fiber facilities will require many years to reach even a small fraction of customer sites, there still will be plenty of growing room for DSL, says DSL advocate Tom Starr, president and chair of the DSL Forum (Fremont, Calif.).
Verizon recently started an effort to increase DSL availability from 60 percent penetration to 80 percent. SBC is working to improve both the speed and reach of DSL services. For BellSouth, Jackson says, ”DSL has been an important service and a good product, but it was never seen as an endgame. We will, however, integrate it into the new offerings.”