Wireless workaround: Teligent, Remec design solution for line-of-sight issue

Teligent is used to creating concepts for new technology and working with vendors to realize those visions, being one of the first broadband wireless operators to push point-to-multipoint.

Most recently, the operator helped develop a repeater product that could make a significant impact on the number of buildings broadband wireless players can reach. "It's making line of sight not such a big deal," said Hamid Akhavan, chief technology officer for Teligent.

Teligent and Remec, a company with roots in developing RF products for the defense industry, had been considering a repeater product when they began working together about 18 months ago.

"They described the system function and came up with a set of requirements, and we explained the technology limitations and choices," said Greg Czuba, president of Remec Wireless. The companies performed tests in Teligent's lab, and Remec has built some of the products that Teligent will test in the market. If trials are successful, Remec will begin to manufacture the products, and Teligent will roll them out on a wider scale during the second half of the year.

The solution operates like a typical repeater. For example, if a Teligent hub site can see a tall building but not a shorter building behind it, Teligent can place the repeater on the tall building and use it to extend the signal to the hidden shorter building. The same method can be used as an inexpensive way of dealing with interfering buildings (see figure).

But the repeater doesn't just connect one building. In one scenario, one sector of a hub site might serve six customer sites and one repeater. That one repeater can communicate with eight other customer sites, Akhavan said.

"If we didn't have the repeater, we'd use wireline or put up a second base station for those eight customers. That's far more expensive," Akhavan said. The repeater costs from $5000 to $10,000.

"So a $10,000 product can solve a $200,000 problem," Czuba said.

An operator couldn't, however, install one hub site and essentially use repeaters to cover an entire city. "At the end of the day, we're limited by the total capacity of the base station," Akhavan said.

The repeater can operate with base station equipment from any vendor, a characteristic the companies have filed patents to cover. Teligent has exclusive rights to use the product until the end of the year, at which point Remec can court other operators.

"They understand why it would be beneficial for Remec to sell this product even to competitors," Czuba said. "They're just looking to gain a head start for having developed the idea."

For the past year, Teligent also has been testing laser technologies from a leading supplier it cannot yet name. In certain environments such as campuses where distances are short but traffic is high and where fog is rare, the technology could work, Akhavan said.

Teligent also has tested voice-over-IP solutions. "That would allow us to move our network to the next level of efficiency," Akhavan said.

In addition, the operator has been working with up to 50 vendors testing integrated access devices (IADs), which can eliminate the need for operators to send technicians to a site to provision services. "IADs require the greatest amount of attention. They are a big driver of operational costs," Akhavan said.

Operators are demanding that vendors put more functionality into the IAD to eliminate the need for multiple pieces of equipment at the customer site. For example, Teligent usually installs a DSL access multiplexer, an intelligent channel bank, a router and other devices at the customer site. An IAD can help integrate those different functions.

"We try to put as many pieces as we can into the box," said John Kasha, director for DSL product strategy at Lucent Technologies. Lucent recently announced it will supply a new line of IADs to Winstar Communications. Lucent incorporates the ability for the IAD to interface with a number of different technologies such as DSL, T-1s, digital loop carriers and Ethernet ports. That's important because some operators use multiple technologies or have plans to migrate toward different technologies, Kasha said.