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It's a Wi Wi World

New wireless technologies extend connectivity near and far.

By Nancy Gohring, Network World
March 15, 2004 12:07 AM ET

Network World - WiMax and ZigBee. No, they're not filling in for Siegfried and Roy on the Vegas strip or replacing Regis and Kelly on television. They're two new wireless technologies that belong on your radar screen.

First off, let's get the definitions straight. WiMax, which stands for Worldwide Interoperability for Microwave Access, is a WAN technology that can beam broadband signals up to 30 miles from a cell tower.

The 802.16 standard, which the WiMax Forum industry group is pushing, is designed to operate in unlicensed or licensed frequencies from 2 GHz to 66 GHz. It's being touted initially as a last-mile alternative to DSL and cable modem. Ultimately, WiMax proponents see it as the basis for ubiquitous, continuous mobile wireless connectivity.

Picture mobile workers with dual WiMax/Wi-Fi cards on their laptops. They connect via WiMax while moving and switch to Wi-Fi at a hot spot or inside a Wi-Fi-enabled building. While WiMax is designed for long-range, high data-rate communications, ZigBee is at the other end of the scale, offering low data rates at short distances.

The ZigBee Alliance is the driving force behind the 802.15.4 technology, which operates in unlicensed spectrum, including the crowded 2.4-GHz band. It can transfer a mere 250K bit/sec of data within a range of 30 to 200 feet.

The big plus for ZigBee is that it requires minimal power, which means a ZigBee-based device could run for as long as five years on a single battery. The Alliance sees ZigBee playing a role in mesh wireless LANs, wireless desktop peripherals and industrial sensing devices that can be monitored wirelessly across a network.

Standards battles

The 802.16 standard aims to initially compete with DSL and cable modem service. It is expected to solve some problems that faced the multipoint multichannel distribution system (MMDS) license holders who tried to build a market in the mid-1990s, and current small operators using 802.11 to bridge the last mile.

From a single base station, an antenna can transmit as much as 75M bit/sec of bandwidth for 2 or 3 miles. Throughput declines as the distance increases, but proponents say a WiMax signal can extend as far as 30 miles, depending on how wide a spectrum band is used.

"The demand for broadband is ever marching onward," says Carlton O'Neal, vice president of marketing for Alvarion, a developer of point-to-multipoint wireless systems. "At the same time, the big carriers say they can do DSL and cable to X percent of their users but they can't do it to all." With 802.16, those operators and others could use licensed or unlicensed bands to reach customers they can't serve with the other technologies.

Industry observers have high hopes for 802.16. A recent study from ABI Research reports that broadband wireless equipment sales should surpass $1.5 billion by 2008, mostly because of WiMax.

As with any attempt to create a standard, there are hurdles that need to be overcome.

The 802.16 effort is a confusing alphabet soup, but proponents hope to converge various subsets under one all-encompassing WiMax label.

For example, 802.16a added the 2-GHz to 11-GHz bands to the original 802.16 proposal, which spanned frequencies from 10 GHz to 66 GHz. The 802.16a standard was ratified in January 2003, but it doesn't solve one of the main problems - expensive customer installation - that caused the MMDS market to fizzle in the mid-1990s.

MMDS operators spent as much as $3,000 per customer setting up external antennas on customer homes or offices, says Lindsay Schroth, an analyst with The Yankee Group. "It was so difficult to get a return [on investment] so we saw them pull out of the market," she says.

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