Fiber at home in pcs?

Aug. 1, 1997

Fiber at home in pcs?


Sanders, a Lockheed Martin Co., in Nashua, NH, will add its name to the growing list of companies touting the benefits of fiber in personal communication services (pcs) networks following a successful technology demonstration in Pittsburgh, PA. pcs networks could prove a burgeoning market for fiber, say analysts. However, the market may prove difficult to crack.

pcs networks, like cellular systems, provide communications services via radio-frequency (RF) signals transmitted and received by antennas. These networks operate over different frequencies than cellular, however--close to the emergency broadcast bands, according to Stephen Montgomery, vice president and chief operating officer of San Mateo, CA-based ElectroniCast Corp., a market research firm that has studied both the pcs and fiber industries. The most common use of pcs-like technology is the cordless phone found in many homes, he says.

pcs providers envision expanding the service outside the home in competition with cellular, however. In a typical application of this type, an antenna located atop a large tower would control traffic in a relatively broad area, or macrocell. It would feed signals from the macrocell to a base station close by, which in turn, would pass the signals to the public telephone network.

However, the large number of pcs licensees, combined with scarce real estate, sometimes makes it difficult to construct a tower big enough to control a macrocell, according to Sanders sources. The solution, they say, is to distribute the large antenna functionality to smaller antennas spread throughout the intended coverage area, creating a network of microcells. These microcells can then be linked to the base station via optical fiber.

The Sanders solution, called pcs Over Fiber, involves a remote RF head, which includes the antenna functionality in the form of a transceiver, power amplifiers, and an RF-to-fiber converter/interface (see photo). At the other end of the fiber link is a pcs hub, which consists of a converter unit--which converts the optical signal back to pcs frequency for transmission to the nearby (perhaps collocated) base station equipment--and an operator interface for network management and control. Besides obviating the need for a large antenna tower, this scheme also provides coverage to areas where topology would create "holes" in conventional pcs macrocell networks.

Montgomery sees a need for pcs microcell technology. "In a lot of these small towns and business areas, having another [large] antenna is just not going to happen," he explains. "So you have to have these small antennas hanging off telephone lines or even built into the architecture of buildings so you can`t even see them."

The fact that pcs firms are struggling to extend the coverage of their networks provides a great opportunity for fiber, Montgomery believes. "I think it`s really important that the fiber-optic industry is looking at this," he says, "because you`re not only going to have the capability of using this fiber for pcs, but also for other reasons. And then you can use existing fiber and lease existing lines to go ahead and string up pcs antennas."

Companies have begun to realize the potential of fiber/pcs combinations, say Sanders sources. "We`ve received a tremendous amount of interest in this product," claims Chris Cole, senior marketing manager in the Telecommunications Systems Div. of Sanders. "The number of players in the pcs industry that are experiencing difficulty with their tower approvals is astounding. Beyond that, there are people looking at using this for hole-filling. We`ve also inquiries from people who own fiber-optic networks who are looking for other services that they could place on those networks."

Cable-TV market

Cable-TV companies represent one sector that could benefit from carrying pcs services on their networks, says Montgomery. Sanders has developed a product specifically for this market, called pcs Over Cable. While the company has high hopes--and even a customer--for this product, Cole points out that the fiber version of its technology provides coverage of a wider area, due to a more robust power amplifier and the ability to locate the antenna unit higher than the 23 ft, where most aerial cable-TV plant resides.

Yet Sanders may find this market difficult to penetrate, as adc Wireless Systems Group, Portland, OR, can attest. "It`s a pretty complicated sell," says Joe Roissier, director of marketing for the group. The problem, he says, is finding potential customers who have both a pcs license and existing fiber or coaxial-cable plant. "If you don`t find a company that has that under a single roof, then you have to go out and separately convince each party that it`s in its best interest to support this technology."

Roissier says that because only a handful of companies qualify as one-stop customers, selling pcs over fiber or coaxial cable can involve a lot of leg work--more than adc currently wants to perform. "I think the market ultimately will materialize, but at this point, there are [only] two or three large customers. So we decided to reallocate the development talent from that project," he says.

"From a technology perspective, it works," Roissier concludes. "But the economic model hasn`t proven in 100% yet, I don`t think. It may over time; we`re watching it closely." q

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