newspage.com
Broadband Wireless: The Big Hertz
May 21, 1999
Inter@ctive Week via NewsEdge Corporation : The sudden surge of involvement among major telecom players in wireless broadband communications reflects new gains in the underlying technology that offers operators much more bang for the hertz than they've had to date.
While wireless broadband pioneers Teligent (www.teligent.com) and WinStar Communications (www.winstar.com) continue to build out their local networks, wireline carriers including AT&T, MCI WorldCom, NextLink Communications and Sprint have secured spectrum for deployment of advanced point-to-multipoint systems as a low-cost, quick way to bring high-speed connectivity to businesses.
Now that these operators finally see what they need to give them the confidence to pursue broadband wireless strategies, the conditions look right for additional crossovers into wireless territory.
"There's a big difference between what people have had to work with in the past year or so and what we're looking at now," says Todd Wolfenbarger, a spokesman for Next-Link (www.nextlink.com), which last month added to its spectrum holdings by buying Local Multipoint Distri-bution Service (LMDS) license holder WNP Communications.
NextLink, whose major stockholder is cellular pioneer Craig McCaw, already held the 13 A-block (1.15 gigahertz of bandwidth) and 29 B-block (150 megahertz) LMDS licenses won by NextBand Communications, the joint venture it shared with Nextel Communications before buying out Nextel's stake.
The deals leave NextLink with 1.15 GHz of spectrum to use in territories covering approximately 95 percent of the population in the top 30 U.S. markets, which is far more spectrum per market than its rivals have in most of their markets.
THE SKY's THE LIMIT
With the new technical advances affecting microwave network operations at anywhere from 2 GHz, where MCI WorldCom (www.mciworldcom.com) and Sprint (www.sprint.com) will operate with their planned Multichannel Multipoint Distribution Service (MMDS) networks, all the way to 39 GHz, where AT&T is staked out with its 1998 acquisition of BizTel, there's plenty of room for more players, says George Harter, chief technology officer of Hardin & Associates, an engineering consultancy.
"Wireless supports bandwidth-on-demand and a selective targeting of capacity into potentially lucrative markets," Harter says. "There are differences in performance characteristics and line-of-sight issues among the various spectrum bands, but the viability at any frequency tier is really a function of how well you design your system."
Harter says that MCI WorldCom, Sprint and others using the MMDS frequencies with only 200 MHz to work with will have an approximately equal amount of effective bandwidth to use as operators of LMDS networks, even though LMDS licenses offer more than 1,000 MHz of available spectrum. The reason is that the lower frequencies used in MMDS support higher levels of modulation systems and, therefore, higher numbers of bits per hertz.
The Federal Communications Commission (www.fcc.gov) has begun the process of opening additional spectrum bands for fixed wireless applications, including 25 MHz at the 4.6-GHz level and a whopping 1.4 GHz at the 40-GHz level, Harter says.
The big performance gains in LMDS and other spectrum applications of point-to-multipoint wireless broadband technology start with greater flexibility in the use of bandwidth than was previously possible.
In one such technology development, Newbridge Networks (www.newbridge.com) has begun shipping systems that have Time Division Multiple Access built into the company's underlying Asynchronous Transfer Mode (ATM) transport format. The TDMA build-in means operators can deliver a variety of services to different users over a single wireless channel, rather than having to dedicate everything on that channel to one user, says Alain Brazeau, director of product management for wireless networks at Newbridge.
With the addition, the ATM Radial Interface Card that is at the heart of the Newbridge system can deliver individual line services down to DS-0 (64-kilobit-per-second) rates, aggregating up to 21 megabits per second over an 18-MHz wireless channel or to 42 Mbps over a 36-MHz channel, Brazeau says. Each card also supports two return streams, aggregating up to 10 Mbps each over two separate 9-MHz channels, Brazeau says.
By next year, he adds, Newbridge plans to introduce Frequency Division Multiple Access technology, which will push the throughput of a single ATM Radial Interface Card to OC-3 (155-Mbps) rates.
"We're working with several operators in addition to ones already announced in preparations for commercial rollouts," Brazeau says.
So far, Newbridge has won contracts for LMDS deployments from Central Texas Communications -- the first LMDS bidder to get commercial service off the ground with rollouts in three Texas markets -- as well as one operator in South Carolina and another in Kansas.
Newbridge also is the supplier to Canadian operator MaxLink Communications and to Korea Telecom, both of which are just getting commercial broadband wireless deployments under way.
Flexible Fliers
While Teligent, which operates its service at the 24-GHz spectrum tier, and WinStar, which operates at 38 GHz, have point-to-multipoint services under way in multiple markets, they, like everyone else, avidly are scouting for new platforms that will support a much more flexible approach to providing services than they've had to date.
Teligent, which now offers service in 26 markets using radio equipment supplied by Nortel Networks (www.nortelnetworks.com), has signed a five-year deal worth up to $250 million to buy radios and supporting electronics from Hughes Network Systems (www.hns.com). The Hughes AIReach system "will give Teligent additional flexibility in our network deployment, enhance our radio capabilities and create more competition in the broadband wireless equipment marketplace," says Kirby Pickle, president and chief operating officer at Teligent. The new Hughes radio integrates access multiplexing into a single, unified networking solution and provides high spectrum efficiency by transporting information at speeds of 45 Mbps over a 12.5-MHz frequency channel, Pickle adds.
. . .
>>>> |
