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Optoelectronics & Communications

Technologies merge in multimedia network

From OE Reports Number 188 - August 1999
31 August 1999, SPIE Newsroom. DOI: 10.1117/2.6199908.0004

Bolstered by stunning Internet growth, telecommunications companies around the world have turned to optoelectronics and fiber optics as a solution to meeting bandwidth needs. Fiber is versatile, rugged (once in the ground) and can carry many terabits of data on a single line-but it's not perfect.

Laying fiber cable is expensive. Just like for utilities and conventional telephone lines, rights of ways have to be purchased, land leases negotiated, trenches dug, and technical crews paid. As a result, some experts are wondering how far fiber will go. In the U.S., "fiber to the home," once the mantra of the optoelectronics industry, is going the way of the optical computer, vanishing into the "circular file" of unrealistic and costly ideas.

As a result, companies are looking to other technologies such as cable and wireless communications to provide the final leg to the consumer's lap-, set- or desktop. Some experts are even positing a world where wireless Internet communications may replace the expensive power of fiber optics in rural areas. Multimedia is the game and the telecommunications and media distribution companies are sidling up to the table, placing their bets through mergers and acquisitions about how to best meet the multimedia needs of a new world.

Changing our ideas about the Internet

If the Internet were a sentient creature, it would certainly be proud of its accomplishments; after all, it has changed the world. But as it matured, the adolescent technogod would learn-as the rest of us have-two basic truisms: (1) One can change the world, but it almost certainly changes one in return, and (2) give them an inch and they'll want a mile.

New applications and an increasingly mobile populace represent the forces of change that face the Internet and its associated companies. Computers are already finding their way into briefcases, breast pockets, and belt loops-consider IBM's Thinkpad, for example. The old network model of modem and copper wire to fiber optics and back cannot meet our needs on the golf course as well as the digital assistant can (at least, not without a very long telephone wire.) As this new era of data sharing begins, network designers must somehow anticipate an infrastructure that meets the needs of a diverse global consumer base.

As a result, telephone giants are considering the merits of voice data following the path of the Internet's text and imagery. Many experts expect voice data will soon follow the IP protocol. Today, a landline voice circuit is opened when a telephone call is made and remains the same for the duration of the conversation. Packet-based Internet protocols send data wherever an available line exists, just as long as it gets from point A to point B. Wireless communications bridges the two, with a shifting circuit that changes between open channels with the strongest signal. Although these varying methods complicate a network designer's job, companies love options-especially when the right solution means lower costs with greater service and a chance at increasing market share.

Pressing applications

Speak to three telecommunications experts about which applications are driving the multimedia revolution and you'll get as many answers. Unlike applications for most developing technologies, however, dreamy Internet applications are as likely to become reality as a George Lucas film is likely to make money.

Dwight Streit, director of telecommunications products in TRW's Space and Electronics Group (Redondo Beach, CA), looks to Europe as the best example of an exploding mobile multimedia world. The European boom is due, in part, to the advent of the G3 telephone. Developed by Nokia and others, this new flip-top wireless telephone resembles a communicator from Star Trek more than a standard cellular telephone. These phones, which offer internet connectivity, teleconferencing, and a host of other services, provide wireless data rates from 128 kb/s to video rates of 1 Mb/s. "It's the same idea as the Palm Pilot, although the Pilot isn't as fully wired [into the Internet]," Streit said.

Streit said part of the reason for the significant European growth in this market is due to commercial expansion into the Ka-Band. Streit, who develops gigahertz microelectronic amplifiers, receivers, and other devices for dense wireless communications, believes wireless Internet services could go completely RF with satellites bridging the gaps between base stations. Alternatively, he said designers may take a hybrid approach that uses optical fiber to connect base stations. "It depends on location," Streit said. "If there's a fiber handy then it's cheaper, but the point is that there's not that much fiber in the ground. If you're in a financial [urban] area, there will be fiber nearby, but there are a lot of [rural] areas that don't have access to fiber.

Because of government regulations, wireless bands are extremely limited while the demand for wireless bandwidth continues to exceed expectations from year to year. "You need gigahertz bandwidth for these multimedia applications," Streit said. "When you do much denser modulation schemes, it puts extreme requirements on the microelectronics-the power amplifiers need extremely linear response with good phase and amplitude control, and that's where we fit in."

Consumer forces

Radaha Nagarajan of SDL Inc. (San Jose, CA), however, questions whether a pure wireless network will ever be able to keep up with demand. "If you look at telco companies that bury fibers for trunk lines and backbone networks, they're operating at higher and higher capacities, moving from 2.5 to 10 GB per channel. Electronics can't keep up," Nagarajan said.

Although Nagarajan, who focuses on fiber optics transmission and engineering, questions the feasibility of a large-scale all-RF multimedia network, he agrees that RF distribution will play a crucial role in future networks. "People talk about mobile services. This is a platform that is not connected," Nagarajan said. "It could be a car, it could be a remote location-like military posts. It could be an airplane or a shipor digital distribution of movies to theaters.

"You start with the high-end data bank where you need the highest throughput and you fox a fiber optic node there," Nagarajan continued. "As you move further downstream, you have a variety of optionsTelco's own twisted pair and the cable companies' own coax, and then of course there's the wireless companies [In these scenarios], wireless is the last link."

Ilesanmi Adesida, a professor of electrical engineering at the Univ. of Illinois in Champaign-Urbana, believes his native Africa may represent the best example of a situation where a hybrid wireless/optical fiber network will play a decisive role.

"Wireless will be important in terms of speed and accessibility for schools in rural areas and business-to-business communication," Adesida said. "Gigahertz optoelectronic wireless components will become very important. Small companies are working on these wireless technologies and the big companies are looking to acquire the technology instantly."

Perhaps in this scenario, satellite links will play an even larger role. Nagarajan said satellite transmission is a possibility in some circumstances, although he added that on the world's only commercial satellite communication system, Iridium, "the data rates are kind of slow." That could change, however, if free space optical communications provided the spaceborne bandwidth required for these applications. Unfortunately, Nagarajan admits, financial interest in these kinds of systems is lagging, mainly as a result of the success of terrestrial fiber optics.

Wireless communications face many challenges on several fronts, Nagarajan said. As customers add Internet, e-mail, video, and other services to conventional voice wireless communications, RF engineers have to continue to work on low- and high-power RF transmitters, efficient battery sources, and dense transmission systems that easily shift between cells (coverage area for a particular end-loop transmitter).

At the same time, Nagarajan acknowledges that optical fiber designers also face new challenges. Increasing bandwidth per channel is only one part of meeting the challenges posed by multimedia communications. With the advent of extended range erbium amplifiers and the even newer Raman amplifiers for the lower end of the telco transmission window, Nagarajan believes fiber will eventually have to allow low-loss transmission all the way across the 1.3 to 1.5 telco window in order to meet demand-while developing new all-optical routing solutions. "The trick is how you route all these wavelengths with high fidelity," Nagarajan said.

Enter a coax solution

Perhaps the closest solution has been in the ground for the past two decades. Coax cable reaches into half of the homes in the U.S. Nagarajan points to AT&T's recent acquisition of Comcast and MediaOne, traditional cable companies that have gone into the Internet provider sector. "You can't neglect the part that cable will play because the infrastructure is already in place," said TRW's Streit.

Data and multimedia distribution across cable modems is still a one-way solution (telephone lines are used for upstream communication and coax for downstream or downloading data). However, when the next generation of cable modems is installed, termed broadband, bandwidths of several hundred megabits per second will be available in both directions.

TCI and other cable companies are making serious inroads in cable modems across the U.S. Perhaps the final infrastructure solution will depend on more than technology. AT&T's recent acquisition of MediaOne, which would give the telco giant the largest share of the cable market, is currently under consideration by the Federal Communications Commission (FCC). If the FCC rules against AT&T over monopoly concerns, it will surely impact future networking decisions by the telecommunications companies.

TRW Communications

1900 Richmond Road
Cleveland, Ohio 44124
(1) 216/291-7000
Literature Request Line
(1) 216/291-7755

SDL, Inc.

80 Rose Orchard Way
San Jose, CA 95134-1365
Tel: (1) 408/943-9411
Fax: (1) 408/943-1070

Univ. of Illinois Department of Electrical and Computer Engineering

1406 West Green St.
Urbana, IL 61801
(1) 217/244-6379

R. Winn Hardin
R. Winn Hardin is a technology journalist based in Jacksonville, FL.