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Tripping the light fantastic

Thu, 08/31/2000 - 8:00pm
Michael Lafferty, Associate Editor

When the word "laser" is uttered, you might think about compact discs. You might think about the latest in eye surgery and the miraculous return of 20/20 vision. You could even think about a jiggly red dot darting back and forth across a long-forgotten PowerPoint presentation in some darkened auditorium. Others are reminded of Hollywood-inspired weaponry that cuts through cold, hard steel or soft, pliant flesh. Dropping into a Reaganesque reverie, some even think about Star Wars technology zapping threatening missiles out of the sky.

Some fact, a fair dose of fiction, and a lot of misconceptions surround this Buck Rogers technology that's been around for nearly 30 years (see sidebar, page 28). Since its introduction, a legion of laser-dependent applications have been touted, but far fewer have actually taken hold.

Now, it's broadband's turn.

The last mile chasm

Fiber optics is dandy, but it sure doesn't come cheap. True, these high-capacity glass strands and related electronics have revolutionized broadband telecommunications, but as fiber moves closer to the home, construction costs rise exponentially. So much so, that network operators have to figure their newbuild/rebuild/upgrade budgets to the penny so that they can stretch fiber to its absolute maximum on any given project.

Given that cable operators got in the business to transport entertainment to millions of consumer homes, it's no surprise that fiber upgrades have been concentrated in residential areas. Businesses, office parks and high-rise buildings have traditionally been sidestepped. Quite often, that last mile of connectivity between a business and a cable network has been difficult to justify economically because most cable operators have little to offer beyond entertainment services.

The numbers support the magnitude of the task, as well as the cost of taking fiber into non-residential markets. According to research from Winstar Communications, of the more than 750,000 commercial properties in the United States, little more than 25,000 have been wired with fiber. Another estimate says only about five percent of the office buildings with 100 or more employees have fiber, while 90 percent are within a mile of a fiber ring. Estimates for wiring an existing building with fiber—depending on the size of the building, the market it's located in, and how much ground has to be torn up to complete the job—can range anywhere from $30,000 to $300,000 or more.

Lasers to the rescue?

In the last six months, the last-mile connectivity issue has, by some accounts, undergone a groundbreaking shift with the introduction of improved and reconstituted "free space optics" or "optical wireless" technologies (aka "invisible fiber," or "infrared broadband"). Utilizing low-powered infrared lasers, an entirely new class of products have emerged that carry massive amounts of IP-based voice, video and data through open air at blinding speeds.

This new class of products breaks out in two basic forms: point-to-point and point-to-multipoint technologies. A variation of the former includes a "meshed" topology. Throughput claims for all three are impressive: point-to-point and point-to-multipoint range anywhere from 155 Mbps to 10 Gbps; meshed runs at 622 Mbps (OC-12) speed.

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A hypothetical setup of the OptiMesh system in Boston (Fenway Park is shown in the upper left-hand corner). The blue outline represents fiber installed in the ground, and the red lines represent optical links.

In fact, point-to-point laser-based data transport isn't really new. It has been utilized primarily in large campus LAN-type situations. These point-to-point systems involve establishing an optical data connection through the air with rooftop lasers that are meticulously aligned and calibrated.

It's the recently introduced point-to-multipoint and mesh topology laser products that have caused a stir among technology watchers and broadband telecom professionals alike. Two companies that until recently were in virtual stealth mode have led the charge in broadband laser connectivity—AirFiber Inc. and TeraBeam Networks. A third company, Optical Access, which recently acquired two point-to-point laser companies (see sidebar on page 30), says it will soon offer its own meshed solution.

AirFiber's OptiMesh topology supports a mesh network of point-to-point wireless optical links using 785 nm lasers, each operating at 622 Mbps. The links are established between rooftop nodes that serve as an access point for that building, as well as a relay point for traffic originating elsewhere in the mesh. Each pole-mounted node is equipped with up to four optical transceivers, a standard drop to the building (an OC-3c/STM-1 or OC-12c/STM-4 interface), a control processor, a compact ATM switch that picks out the traffic for the building it serves, and cross-platform element management system software. The company claims the OptiMesh system will deliver 99.999 percent reliability.

TeraBeam's Fiberless Optical Network system features a point-to-multipoint (hub-and-spoke) configuration using 1550 nm lasers. At the heart of the technology is a transmitter/receiver that is about the size of a small satellite dish (estimated to cost about $150 to construct) that can be placed in a window. In the center of the system are four hub devices that are placed at a building's point of presence (POP) to distribute laser transport streams within a 1-km cell. Each device covers its own 90-degree section. Erbium-doped fiber amplifiers boost signal strength, sending out 1.25 Gbps (IP over Ethernet) to client transmitter/receivers in each quadrant. Those users, who have distinctive IP addresses to pick our their own encrypted traffic, then share that bandwidth. The company says users will be able to send upstream traffic at speeds up to 1 Gbps through a return point-to-point connection. The company claims its system will deliver 99.9 percent reliability.

Not only are their particular approaches to laser transport (in both their technology and business models) getting noticed, it's who is backing them that's generating just as much, if not more, interest.

Technology watchers and analysts first perked up their ears in early March when it was revealed that Dan Hesse, then chief executive at AT&T Wireless, was walking away from millions of dollars in stock options just before the company's widely-anticipated IPO. Hesse became TeraBeam's new CEO and five percent owner. This news flash hit the airwaves just days before the company introduced its Fiberless Optical Network system at the PC Forum in Scottsdale, Ariz.

Hesse's jump was apparently soon justified when TeraBeam and Lucent Technologies announced that they would pool their resources to form a new company (TeraBeam Internet Services) to deploy TeraBeam's technology. In that arrangement, Lucent will invest cash, research, development assets, intellectual property and its own WaveStar OpticAir point-to-point wireless system valued at $450 million, in exchange for 30 percent of the joint company. The newly-formed company is expected to combine Tera-Beam's ability to connect base stations with customers and Lucent's base station networking prowess.

In late April, AirFiber announced Nortel had taken a lead role in a $37.5 million equity funding syndicate that also included Qualcomm. Obviously, it was no accident that at about the same time, AirFiber introduced its OptiMesh wireless optical networking product. Things were definitely coming together in the brave new world of wireless optics.

The good...

Broadband laser transport, no matter who's manufacturing the equipment, is by no means a slam-dunk. Laser technology has some inherent strengths, weaknesses and misconceptions that have to be understood and weighed against one another.

On the good side, lasers do not require spectrum licenses and the exorbitant prices that go with acquiring them. While roof-top access or rights-of-way may be needed for TeraBeam's hubs or AirFiber's nodes, many believe that once landlords understand the value they add to a building through the high-speed connections tenants will have access to, agreements will follow quickly.

In addition, service providers don't have to deal with the regulatory nightmare and resulting expenditures that accompany construction and trenching operations that are needed to build or upgrade wireline networks. Lasers can also deliver data at least 10 times faster than competitive fixed wireless (MMDS) technologies. And, lasers don't require expensive regulatory licenses that fixed wireless operations are saddled with.

To top it all off, laser equipment costs are decidedly cheaper and installation times are distinctly shorter than fiber systems.

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McVeigh

"We really compare ourselves to fiber," says Janet McVeigh, vice president of marketing for AirFiber Inc. "You're looking at getting fiber from the street into a building in a downtown area running anywhere from $100,000 to $250,000 a building. And we're running $25,000 to $30,000 a building.

"The thing that our carrier customers find even more compelling is that it's taking them four to 12 months in the United States to get fiber into a building. In Europe, it's one to two years. And in Japan, they just laugh when we talk about how long it takes to get fiber into a building. We're doing it in just days. So, a lot of our customers find that almost more important than the capital expenditures benefit."

The bad...

Laser technology, however, does have its limitations. Weather is one. While rain and snow can be a real hindrance for MMDS or LMDS systems, most agree that barring a complete blizzard or a virtual Noah's Ark-type rainstorm, current laser-based transport systems can still perform adequately. It's fog that's a problem.

Fog can act like a brick wall to lasers. That's because the moisture particles are so small and dense that they act like millions and millions of tiny prisms. When a band of light like a laser tries to blast through, the signal gets distorted and dissipates. The problem is exacerbated as the light beam fades and spreads out over long distances. Cranking up the power to cut through the fog poses safety issues.

To counteract the fog factor, meshed topology proponents shorten laser links from a maximum of 500 meters to the 200-meter range. Point-to-multipoint systems, says Steve Gartside, senior vice president of corporate development at TeraBeam, adjust cell size for the worst-case scenario. "Just like the LMDS guys who engineer for worst-case rain, we engineer for the worst-case fog. So with a city that has a lot of fog, we build a smaller diameter cell size. We design it so that whether you're in Phoenix or San Francisco, you still get three nines of availability."

Two other point-to-point vendors (LightPointe Communications Inc. and AstroTerra Corp.) combat fog with a unique backup transport system. It's been reported they're developing products that use unlicensed microwave radio frequencies to transmit laser-based traffic that's being blocked by fog.

Another issue for laser transport systems is building movement. Buildings sway in the wind and, over time, they settle into the ground. When the sun comes up, they expand. When the sun goes down, they contract. For pinpoint laser transmissions, this minuscule movement can wreak havoc with transport service. A number of vendors have developed auto-tracking systems that detect such movements and automatically adjust the lasers accordingly to maintain proper alignment.

Flying objects can also be a problem. The famed flying pigeon hypothesis could put a kink in transmission in point-to-point or point-to-multipoint systems that provide only one path for traffic. With mesh topologies, there's always an alternate path. But one-path proponents note that it would have to be a pigeon of Godzilla-like proportions or a swarm of pigeons straight off the set of an Alfred Hitchcock film to really interrupt laser-based transport.

The ugly...

When it comes to safety, this is where many misconceptions rear their ugly head. This is when the flying pigeon hypothesis is transformed into the cooked-goose theory. People have seen too many movies where evil geniuses use powerful laser weapons to conquer the world or slice and dice an enemy.

The truth of the matter is that the lasers used in broadband transport use less power than a laser pointer. No pigeon will get cooked if it flies into a laser transport beam. Nor will anyone go blind should they somehow figure out how to pass through an airborne transport stream located several stories above the ground.

It's all business

From all indications, this market segment will only get busier. CLECs, ILECs, DSL and all other manner of broadband service providers are looking for an economical way to tap into a very lucrative market that's essentially just sitting there waiting for high-speed, high-capacity transport/access.

Companies like AirFiber will be manufacturing equipment that a host of providers can purchase and install. TeraBeam has decided to take a different tack—planning instead to both produce equipment and build its own laser network umbrellas in selected high-density metropolitan areas in North America, and eventually, internationally. The company, in its TeraBeam Internet Services incarnation, will then act as a service provider.

Both companies have either beta tests or actual trials ongoing in North America and overseas. These operations, when concluded, could help counteract the disbelief some detractors have in upstream/downstream speed and reliability/availability claims made by both companies.

Yet terrestrial solutions for broadband laser transport could only be the beginning. Proponents argue that undersea fiber optic cables could be obsoleted by wireless optics. A few technology experts are keeping their eyes on the heavens, noting that light travels best in space. A long-distance network of laser-linked satellites seems increasingly doable with each passing day. It would seem that once Earth's optical wireless needs are met, the sky is quite literally the limit.

E-mail: mlafferty@cahners.com

 

Lasers 101

The word "laser" is actually an acronym for Light Amplification by Stimulated Emission of Radiation. That's all well and good, but what does that mean? The first laser, invented in 1960, was a ruby laser developed by Theodore Maiman at Hughes Laboratory in Malibu, Calif. The key concept behind a laser is based on the way light interacts with electrons.

Depending on a particular atom or molecule, electrons exist at specific energy levels or states. These energy levels can be imagined as rings around a nucleus. Electrons in inner rings are at lower levels than those in outer rings.

Electrons can achieve higher energy levels by injecting energy via a flash of light, for example. When an electron drops from an outer to an inner level, "excess" energy is given off as light. The wavelength, or color, of the light given off is precisely related to the amount of energy released. Depending on the particular lasing material being used, specific wavelengths of light are absorbed (to energize or excite the electrons) and certain wavelengths are emitted (when electrons fall back to their natural level). The first ruby laser stimulated excess energy with the use of a fully reflecting mirror and partially reflecting mirror, a compact, high-intensity lamp and a crystal of ruby formed into a cylinder (the lasing material).

The laser flash that escapes through the partially reflecting mirror lasts for only about 300 millionths of a second, but it's very intense. Early lasers could produce peak powers of nearly 10,000 watts. Modern lasers can produce pulses billions of times more powerful

The laser landscape A number of companies have sprung up to produce laser-based transport systems. A few key players are listed below.

Point-to-point providers:

Astro Terra Corp. www.astroterra.com Canon www.canobeam.com LightPointe Communications Inc.www.lightpointe.com Jolt Ltd. www.jolt.co.il OrAccess Inc. www.oraccess.com Pav Data Systems Inc. www.conversant.com TeraBeam Networks www.terabeam.com

Point-to-multipoint providers:

TeraBeam Networks www.terabeam.com

Mesh providers:

AirFiber Inc. www.airfiber.com Optical Access Inc* www.opticalaccess.com

[*Optical Access Inc. was formed by its parent company, MRV Communications Inc. ( www.mrv.com ), after MRV acquired both Jolt Ltd. and Astro Terra Corp. earlier this year.]

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