FTTH in my lifetime? Please!
SPECIAL REPORTS: Access Networks
The United States risks falling behind the rest of the world without more fiber in access networks.
LAWRENCE FOLTZER, Turin Networks
Editor's note: Lightwave does not have a department for outside editorials, particularly one the length of the article that follows. However, Lawrence Foltzer's passion for the subject- plus his comments on current and emerging technology-led me to conclude that our readers, including those outside the United States who have an interest in U.S. telecommunications policy, would find his thoughts provocative. I welcome your responses to the comments in this special report; we'll publish the best in a future issue of Lightwave.
In 1975, I attended the first Optical Fiber Communications (OFC) Conference, held in Williamsburg, VA. I had been in the fledgling industry for two years at that point, working on the first Defense Advanced Research Projects Agency (DARPA)-sponsored fiber-guided missile program. We needed lots of fiber for our experiments, so we built a fiber draw tower in the basement, and fiber-in-my-home became a reality. But some 27 years later, the dream of fiber-to-the-home (FTTH) seems more distant than ever as our industry's progress is stalled by lack of vision on the part of both the private sector and government.
The network built upside-down
During the 1980s and '90s, home computers, bulletin boards, and the Internet launched the first wave of expanding appetite for data communications. It seemed like magic to be able to exchange files and link up to the world, even if only at 300 baud. Not a single hair was ruffled by this new dynamic since the infrastructure of the time was ready to absorb the next few cycles of modem technology advancement.
But then data took on a different character as video compression technology came to the fore, spawning the current market for high-definition television (HDTV) and the promise of global access to video libraries via the Internet. From the perspective of the network, the pressure first became evident where traffic aggregation is highest: at the core. It was natural to work the problem there, and everyone did, anticipating the continuing march of the Internet economy.
However, the source and sink of all that data, the access network, was neglected, and that is why we currently find our industry in such trouble with dark fiber everywhere. To revive the industry, we now have to invert the model and increase bandwidth to the subscriber so that they can fill those enormous pipes in the metro and core networks. Some of the known "killer applications" that will consume the bandwidth are switched digital video; HDTV; real time, full-motion, high-resolution, video teleconferencing; distance learning; and video-phone-to-the-grandparents.
Societal benefits of fiber-to-the-home
Some of the benefits to society that will result from the deployment of FTTH technology are as follows:
- Decentralized communications infrastructure. Decentralization would reduce vulnerability to natural disasters, system failures, and terrorist attacks.
- Reduced stress on transportation systems. Reduced traffic will result in lower maintenance costs and fewer highway fatalities.
- Improved educational systems. There will be less reliance on "brick and mortar schools" as distance learning becomes a real option. Paced learning can be tailored to individual student needs. Also enabled is growth of the Internet University concept that is being explored by the Massachusetts Institute of Technology and others.
- Reduced business travel. That is a given.
- Greater work at home opportunity. Telecommuting will be enabled by high-speed database access and real time videoconferencing.
- Job creation at all levels. From installers to terminal makers and from software to services, lots of new products and services (the proverbial killer applications) will be possible with the dramatic increase in bandwidth made possible by the FTTH network.
- High-tech gadgets. Greater communications will spur innovation in a variety of fields.
FTTH cost: a brief perspective
In 1977, while working at the ITT Electro-Optical Products Div., I helped put together a bid for what was the first proposed trial of an FTTH system in North America for Saskatchewan Telephone Co. Singlemode fiber and lasers of any sort were pipe-dreams then, as were speeds above 100 Mbits/sec. Equipment cost per subscriber then was in excess of $30,000, roughly the same cost as a home in that era.
FTTH equipment costs today, however, are less that 0.2% of housing cost (less than $150), and an increasing number of us have gigahertz personal computers, HDTVs, camcorders, and digital video cameras, all eager to generate and consume tens of megabits per second. This equipment cost estimate begins at the optical layer as the front end of a set-top or TIVO box and includes a 100-Mbit/sec optical transceiver and framing electronics. The estimate also includes the amortized cost of a curbside optical-network unit (ONU) and the shared cost of the access-edge aggregation device referred to as a host digital terminal (HDT) in Telcordia parlance.
The bottom line is that the cost of an optically fed set-top box can compete with alternative solutions. With a commitment to deploy the technology, manufacturers of optically fed consumer electronics terminals will be happy to deliver the goods.
For FTTH to succeed as a nationwide infrastructure, we must examine the full range of technologies available today with an open mind. If we fail to do so, we only harm ourselves by placing FTTH at an economic disadvantage, which will only further delay implementation. This "cost is king" mindset will allow us to achieve the most important goal-getting the fiber installed-while we sort out the other details of protocols, bit rates, and service charges.
850-nm VCSEL. The first technology to consider is the vertical-cavity surface-emitting laser (VCSEL). The development of VCSELs has had a revolutionary impact on the cost of lasers by allowing wafer-scale testing of die before packaging, increasing yield while reducing materials waste and manufacturing time. Some of the other significant attributes of the VCSEL include high direct modulation speed, narrow spectral linewidth, and output-beam characteristics that facilitate simple and more efficient coupling to fiber.
Over the last few years, many vendors have offered 850-nm VCSELs in die form and packaged in everything from TO cans to arrays of eight and 12 lasers in a common package with ribbon fiber interface. The state-of-the-art of these relatively new lasers is mature, having achieved incredible levels of both performance and reliability. These 850-nm VCSELs are appearing now in everything from small-form-factor (SFF) transceivers to 10-Gbit/sec serial transponders operating over multimode fiber (MMF).
Transmitter and receiver arrays made practical by the development of VCSEL technology can serve as a cost-effective replacement for the passive optical splitter in point-to-multipoint FTTH networks, solving security issues with encryption, reducing power and cost, and providing a simple path to further system upgrades. There is only one drawback to this technology, and that is that they emit radiation in the dreaded Telcordia GR-909-CORE 850-nm "no-fly zone." This discrepancy should be corrected as soon as possible, as should the restriction against the use of MMF as well. Time and technology move on, and once again, we need not handicap ourselves in this endeavor.
MMF. Corning Glass now offers a 50-micron core MMF (InfiniCor-SX+) optimized for 850-nm transmission, with a 2-GHz-km bandwidth-length product. Needless to say, these levels of performance leave significant room for upgrading FTTH bandwidth over MMF, particularly since, for the most part, MMF will be used in the "last hundred meters" of the FTTH network. Another important feature of using MMF is its relative ease of termination in the field. The fact that a subscriber may be able to terminate fiber, as is the case for copper, may be more important than currently realized. The ability to terminate the FTTH fiber in the home could potentially allow a homeowners to connect their in-home fiber network directly to the FTTH feed without the need for an interface adapter.
In addition to these breakthroughs, other technological issues need to be addressed.
1310-nm VCSEL. About two-years ago, a number of companies began making preannouncements of 1310-nm VCSEL-based products. But as of today, none are shipping anything other than prototype hardware. So far, the performance data looks promising, and 1310-nm VCSELs are clear winners for SMF links running at high speeds. But the jury is still out in terms of the cost differential between 850-nm and 1310-nm technology, and whether 1310 nm will displace 850 nm in short-distance MMF applications.
Singlemode fiber (SMF). I've often heard it said that only SMF is suitable/allowed for any and all incumbent local-exchange carrier (ILEC) applications, including FTTH. This dogmatic position is supposed to make the ILEC fiber plant a pure and homogenous glass world. But then came dispersion-shifted fiber (DSF), nonzero dispersion-shifted fiber (NZDSF), TrueWave, AllWave, Metro-Cor, LEAF, and polarization-maintaining fiber (PMF), to name a few.
The point is, the requirements should dictate the solution, not the other way around. There is a place for each fiber type, and they have come into existence not to spoil the purity of the network, but to enhance performance/cost ratios, which translates to higher return on investment. Restricting the fiber types available to a specific application only raises the cost for the network and stifles growth.
SMF's rightful place in the FTTH market is in the high-speed links to ONUs, just as it has been in the fiber-to-the-curb markets deployed in the recent past. That is good news, for it means there is no change required in the current infrastructure to support FTTH, save the changeout of the ONU electronic hardware upon upgrade. That makes the curbside ONU the logical demarcation point from which to launch the MMF interface to the home.
Passive optical-coupler technology. Passive optical couplers-specifically splitters and combiners-are the lifeblood of passive optical networks (PONs). But power splitting implies bandwidth reduction and lower subscriber count on upgrade and calls for more fiber in the feeder than an active solution can provide. And as if that were not bad enough, the current state-of-the-art in fiber-optic passive couplers doesn't scale in accordance with Moore's Law. This limitation exists because manual operations are required in manufacturing these devices. Solutions to this handling dilemma tend to trade off some aspect of performance, which modifies the economic equation in other ways for a zero-sum gain.
Plenty of work to go around
Following is a rather quick attempt to size the magnitude of the job to bring FTTH in the United States to fruition. It should provide some appreciation for the magnitude of the task.
The 1999 U.S. census had the number of households at 102 million, and recent data indicates that 40% of all homes have Internet access. If on average 150 m (2x75 m) of six-fiber cable were required to fiber those homes, then we'd need 5.4x1010 feet of fiber at a cost of 3 cents per foot. However, the cost of the fiber-cable sheath dominates the cost of the cable and is estimated at 30 cents/ft for a total cost of 48 cents/ft for the six-fiber cable, or $4.32 billion in cable.
I assumed 75 m was the average length of deployed drop cable. If for the sake of argument all fiber drop cables were trenched, then we would have to trench approximately 325 households per day in each of 50 states for 10 years at $11 million per day, or $22 billion for trenching.
If we assume two lasers per household and a second pair to support the business needs of a household, then 408 million lasers will be required for the FTTH-like links. Honeywell reported VCSEL production at about 30 million units per year in 2000, most of which are currently consumed in optical sensor applications. If 50 companies build links at equal volumes, then each will consume 800,000 lasers per year, which translates to 50 companies about twice the size of a Finisar. The cost: ($2 billion + $1 billion = lasers) + ( $200 million = Si PINs ) + ( $200 million = InGaAs PINs).
The dollar amounts given here are estimates, but they show the relative costs of parts of the system build-out. The above data indicates that trenching cost will be roughly 70% of the link-related expense. The high cost of FTTH deployment shows why the government must be involved. Payback for building the network can be obtained by leasing bandwidth to all that provide services over the network, leading to real competition at the services level.
Space challenge revisited
The country's successful military and civilian space program would not be here today except for the vision and leadership of President John F. Kennedy, who was not a technologist but understood that investment in technology is the path to a better tomorrow. He set the goal and challenged the imagination and expertise of others to put a man on the moon in less than a decade. Had the President sat back and waited for the airlines to develop the technology to put a man on the moon, we'd probably be using slide rules and listening to tube-type radios today. Likewise, if we wait for ILECs and venture capitalists to step up to the investment plate, we will most probably find the United States at a competitive disadvantage-sooner rather than later. And that is happening now, as scores of highly talented engineers and scientists go in want of a job.
Fiber optics has now come of age! Other nations have stepped up to the challenge. Will the United States? Or will the country be satisfied to give up its technological leadership role as a nation? The challenge before the country is of similar magnitude to putting the first man on the moon, requiring a similar level of commitment and up-front "investment." And like the space program and national roadway system, it is the kind of infrastructure that the federal government should manage though a NASA-like agency chartered with setting standards, funding, and coordinating implementation. There will be no shortage of folks wanting to participate in its implementation, but we have knowledge to draw on from the NASA-led effort to assure some level of fairness in establishing a level playing field.
For citizens of the United States, it is our livelihood, our companies, our industry, and the lifeblood of our country at stake, and it will require each and every one of us to register our vote for the future. We must demonstrate our commitment to fiber optics technology by contacting our local carriers and demanding FTTH. And to show our commitment, we must be willing to pay for our future, whatever the cost, because fiber represents the path toward a better future for us all.
So using the good services of the Internet, write your representatives and the office of the President (www.whitehouse.gov) and register your opinion.
Lawrence Foltzer is director of optoelectronics at Turin Networks (Peta luma, CA).