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Are Telcos Headed Back to the Future?

Fri, 02/28/1997 - 7:00pm
Fred Dawson

Are the telcos headed back to the future, with fiber-to-the-home turning out to be proving in at about the timeframe originally projected? The answer is yes, says Pacific Bell CEO Dave Dorman. The RBOC chief sees an aggressive fiber-to-the-home strategy taking shape in the telephone industry, with "at least one major telco" planning to deploy all-optical broadband networks in newbuild installations by sometime in 1998.

While hybrid fiber/coax network technology has proven harder to implement than PacBell expected, "fiber-in-the-loop is going to happen faster than previously supposed," Dorman says, adding, "HFC is still emerging as a broadband infrastructure supporting all services."

More importantly and more accurately, given the fact that HFC is certainly as close to prove-in as FTTH, HFC also means dealing with localities to get permission to dig up the streets, which, says Dorman, "is not easy, as we learned." And, all other things being equal, there's the matter of the bandwidth capacity that comes with an all-optical approach.

"By 2000, fiber all the way to the home will be used to replace local loop routinely," Dorman says. "The idea of 640 megabits (per second) to every household isn't as far-fetched as it seems."

Pacific Bell, soon to be merged with SBC Communications, if California regulators don't balk, is rethinking broadband deployment strategies as wireless cable as well as HFC hit technical and other strategic walls. Pacific plans to launch an all-digital, multichannel multipoint distribution system across the Los Angeles basin in April in a gambit that represents the first real-world showdown between next-generation wireless and state-of-the-art cable. But win, lose or draw in L.A., MMDS options elsewhere are limited or non-existent, officials say.

MMDS is also a limited technical option in regions less ideally suited for wireless propagation than Los Angeles, where flatness of the terrain and minimal building congestion are big pluses. And, in fact, there's a question of how ideal L.A. will turn out to be, despite its line-of-sight accessibility from towers positioned on mountains northeast of the city.

"You've got to wonder how that's going to play in an ocean-walled environment like L.A.," says a veteran of the wireless RF industry, asking not to be named. "Atmospheric reflectivity (in broadcasting) around San Francisco is what made cable TV."

"There are going to be some hard decisions to make," acknowledges Lee Camp, president and CEO of Pacific Telesis Enhanced Services, which has had long-standing commitments to hybrid fiber/coax and wireless approaches to delivering broadband services. Camp's comment is meant to apply to his own company, but it also applies to other local exchange carriers as ever more delays add up to ever more option-sorting in the rapidly changing network arena.

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News of telcos changing course in broadband networking strategies is practically routine at this point in the 10-year, and counting, rampup to broadband communications. The twist this time is that the focus is moving back to where it started, where the grand vision was to deliver all the bandwidth the world could use through a single glass pipe.

Realization of that vision in a one-step deployment may not be ready for prime time, but it may be close enough to be worth waiting for, especially if telcos have the time, and they think they do. "It's not going to be the same forced march we were proceeding under before," Camp says. "Whether you look at it from the standpoint of the implementation pace of the Telecommunications Act or the circumstances affecting cable companies, it seems like things have gone from being on a high vertical ramp to a more moderate rate."

"For the companies we deal with, at least, the timeframe is still in question," agrees Greg First, president of Lockheed Martin Telecommunications, which is acting as systems integrator for SBC Communications' switched digital video (SDV) trial in Richardson, Texas and for a broadband service trial scheduled for next year by Toronto-based Telus Corp. The company is also discussing a broader role with americast, the joint venture into video programming supported by SBC, BellSouth, Ameritech, GTE and Southern New England Telecommunications.

Even if everything was ready to roll on the facilities side, most telcos have a long way to go before they're ready to integrate service management and billing across all categories in keeping with the business structure of broadband communications, First says. Until the business structure is worked out, which means first working out unresolved regulatory issues, there can be no integrated management system, and without that, the facilities question remains in play.

"The basic (software) technologies are there to do everything you need to do at trial scales," First says, noting that this now includes integration of internal and external information and operations systems into an overarching network management system. "But the ways to achieving scalability to fully iterated systems serving millions of people haven't been agreed on."

The issue isn't lack of tools. Even when there are no off-the-shelf solutions, they can be invented using established building blocks, as Lockheed Martin has demonstrated in creating some of the "middleware" for americast and SBC that allows their operating, billing and management systems to speak to each other.

Rather, the issue is cost and necessity. "The impetus behind final decisions on the architecture is really a matter of market timing requirements and (of) today's vs. tomorrow's costs," First notes. "You can wait, and save money in the long run by waiting."

Even where telcos are moving aggressively with one-way video services, the message is that the real game to watch is the waiting game. "Mostly, all of this is about what's going to happen in the next decade, not what's happening now," Camp says.

What makes FTTH much more realistic now than it was in its heyday as the wave of the future a few years back is the emergence of cost-effective new technologies such as dense wavelength division multiplexing and optical amplification, which are already building a strong beachhead, along with a descending cost curve, in the long-distance market. These and related technologies open the way for building relatively low-cost passive networks where the price of the optoelectronic conversion at each household is balanced by the elimination of some steps in the broadband time division multiplexing and demultiplexing processes in the distribution plant.

DWDM in the local distribution loop?

A number of FTTH concepts using DWDM, which combines several wavelengths over a single fiber, are on the drawing boards, says Vince Borelli, chairman of Synchronous Communications, a supplier of optical amplification and DWDM systems. But, first, suppliers must be pushed into making low-cost components readily available, and that hasn't happened.

"We'd have to see a tremendous drop in costs to all of a sudden start doing DWDM in the local distribution loop," Borelli says. "And you need light sources spec'd to the ITU wavelengths, which not many people are doing right now."

But, Borelli quickly adds, the technology is there to build a low-cost foundation on if telcos are serious about pursuing FTTH. "I don't see how you can do FTTH unless you use WDM," Borelli says, noting that the concept has been part of telephone industry planning since Bellcore issued its broadband loop specs five years ago.

But the concept has changed. Where once the thought was that analog signals would be transmitted over the less lossy 1550 nanometer wavelength, retaining 1310 nm transmissions for digital, today, the possibility of DWDM at 1550 may mean that 1310, if it is used at all, is used as the analog video conduit, given the fact that the usable transmission region around 1310 offers too narrow a window for multiple wavelengths. Moreover, 1550 signals are more easily amplified, representing an opportunity to minimize optoelectronic conversion costs in the distribution branching process by using various combinations of time division and wavelength add/drop multiplexing.

One of the latest developments with the potential to drive all-optical communications involves use of polymers as substitutes for glass in active and passive components. Where, in the past, thermal instability and high attenuation have been barriers to exploiting the cost advantages associated with polymer waveguides, manufacturers are coming up with new compounds and processes that appear to overcome a significant portion of the drawbacks, while greatly improving the cost equation for things like dense wavelength multiplexers.

"Multiplexers using polymers are starting to look like credit cards laminated on both sides, though much smaller," notes Earl Langenberg, a telecommunications consultant who was formerly a strategic planner for US West. "Based on what we're seeing in this area, it's beginning to look like fiber deep to the home can become a very cost-effective option."

One of the first companies to introduce next-generation polymer devices is a little known Santa Clara, Calif.-based manufacturer formerly named ROITech Inc. and now called Lightwave Microsystems Corp. The company said it will begin shipping a 1 × 16 wavelength multiplexer in April priced at $12,000 per pair in volume quantities, or less than half the per-port price of silica-based waveguides.

"What we're doing is moving the potential for use of DWDM into the local distribution and other networking niches," says George Ballog, senior vice president of LMC.

"These products are compliant with all the ITU (International Telecommunications Union) standards for wavelength division multiplexers, including channel spacing and isolation between channels, polarization dependent loss, insertion loss and optical return loss."

Plastic optical fiber

LMC is coming to market in stride with what promises to be a sizeable outpouring of new polymer-based products in the months ahead. The Optical Fiber Communications Conference in Dallas last month featured a number of special sessions and events devoted to "plastic optical fiber" technology in recognition of the sudden shift in status for polymers within the fiber optics industry.

"We see polymers as offering a way to manufacture relatively low-cost passive devices, so we're looking at producing 16- and 32-wave multiplexers in the near future," says James Bechtel, senior vice president for Integrated Photonic Technology of Carlsbad, Calif. "It's also important to note that polymer waveguide technology allows integration on a silicon substrate."

This facilitates the inclusion of electronic driver circuits and receiver circuits to provide a very high level of component integration, Bechtel adds. Such capabilities lessen the cost of routing optical signals by eliminating optical-to-electronic conversions, opening ways to marry DWDM with add/drop multiplexing.

This, indeed, is where the polymer concept really gets interesting for DWDM, Ballog notes. "We're developing an integrated chip to serve as an add/drop multiplexer for DWDM systems that should be available commercially by the end of this year," he says.

The company uses a class of polymers known as "polyimedes," developed in conjunction with Hitachi Chemical Co., to address the thermal and optical loss problems. Fabrication entails etching of three-micron "trenches" in silicon, a much lower-cost process than today's .35 micron state-of-the-art circuit fabrication, and then adding the polymer at high temperature, forming a core matching singlemode fiber dimensions.

"We're able to produce a couple hundred devices per silicon wafer," Ballog says. "The DWDM 1×16 chips measure three millimeters by six millimeters, which is another big cost advantage when it comes to the amount of space required to put these devices in the field."

LMC has come up with a way to make the waveguide reactive to electronic impulses generated from circuits in the silicon substrate below the polymer trenches by doping the polymer with materials known as "chromophores." "There's a deep polarity sensitivity in the dopant, so that when you apply voltage, you cause the index of refraction in the polymer core to shift, creating a switching mechanism," Ballog says.

One sign that the fiber solution is becoming ever more compelling is the fact that, in the denser markets of some telcos, the case is now being made for deployment of broadband-capable fiber distribution systems on a cost-benefit basis tied to telephony alone. Nynex, for example, is slated to install some 30,000 lines in the Boston area next year as part of a one-million-home buildout over the next five years in Boston and New York on the assumption that this will cost less in the long run than it would to replace aged copper with new copper links.

"First and foremost, the thing we're trying to accomplish is an upgrade of our network for provision of our basic product line," says Walter Silvia, vice president of broadband. But the carrier will be able to turn the platform supplied by General Instrument Corp.'s Next Level Communications into a broadband network offering video and high-speed data services by inserting circuit cards at central and field switching points, Silvia adds.

With PacBell clearly leaning toward fiber-deep topology, and SBC, Bell Atlantic and Nynex already there with FTTC deployment commitments, FTTH, as the next logical step beyond FTTC, has a potential base of market demand among telcos that could make it a cost-effective option, perhaps even within the timeframe suggested by Dorman. And there's no guarantee that telcos currently deploying HFC will stay on that track if the fiber-deep picture changes.

BellSouth, for example, with 10 cable franchises averaging a few thousand households each and plans to deliver wireless cable in New Orleans, Atlanta, and possibly, Miami, is laying dark fiber in its distribution plant as it goes about its routine copper network upgrades and replacements, notes BellSouth spokesman Kevin Doyle.

"We're not closing any doors to fiber," he says.

So far, Dorman is the only top RBOC executive to suggest FTTH will be a factor in widescale network deployments by 2000. But, if he's right, companies now making commitments to FTTC could find themselves doing the network strategy shuffle one more time, only this time, from a position where the engineering learning curves are a little less steep.

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