Free Wireless Pays Off

The Alaska Marine Highway System has probably pushed mobile wireless LAN technology to its ultimate, says Dan Judd. An analyst/programmer at the Alaska Department of Transportation and Public Facilities, Judd helped develop and deploy a ship-to-shore wireless LAN communications system for the AMHS, which operates ferry ships serving ports in south central and southwest Alaska, the state's panhandle and the Aleutian Islands chain.

The AMHS installed wireless LAN gear on its ships, with the antennas mounted high on the communications masts. And like a growing number of organizations, it's running that equipment in license-free spectrum, communicating with its nine ships on the 2.4-GHz band.

The shipboard systems communicate with access points installed at terminals in 12 ports on routes extending from Bellingham, Wash., the southern terminus of the Inside Passage panhandle service, to Kodiak Island, the jump-off port for the Aleutian Islands.

Looking at the geographical spread of this system, "I don't know of anyone else who is doing what we are doing with wireless LANs," says Judd.

But the AMHS isn't alone in finding ways to use unlicensed spectrum.

The multibillion-dollar spectrum auctions conducted by governments around the world in recent years have seemingly limited access to the airwaves to well-financed global telecommunications firms. But the U.S., Canada, Mexico and some Asian countries have also allocated enough license-free spectrum to allow innovative users to develop and deploy wireless broadband networks at relatively low cost.

License-Free Infrastructure

These license-free bands (see chart) serve as the building blocks for industry-standard wireless LANs used to support users at home or in a corporate or academic campus. They also support fixed wireless systems embraced by a growing number of wireless Internet service providers (ISP) positioning themselves as alternatives to telco or independent Digital Subscriber Line (DSL) providers.

Throughputs on these wireless systems typically run from 512K bit/sec. to 11M bit/sec., but technology enhancements will soon boost speeds from standard equipment to a range from 32M to more than 50M bit/sec.

Although unlicensed wireless LANs may not seem ideal for mobile operations (ranges from an access point - an antenna, electronics and a connection to a wired network - run in the hundreds of yards), several enterprise users like the AMHS have adapted or plan to adapt them to support short-range mobile wireless applications.

As soon as an AMHS ship comes within range of the wireless LAN system installed in the port - tested to a maximum of three and a half miles at sea - the shipboard system locks on and starts transferring e-mail at the rate of 1.5M bit/sec. from an IBM Infinity server with a 70GB hard drive, which is hooked up to 12 workstations on a wired LAN and a Cisco Systems Inc. router on each ship. On shore, the wireless LAN system receives the data and sends it to another Infinity server that routes it to an intranet, which transfers the data from the ships to AMHS's back-end systems in Juneau.

Data transferred by the store-and-forward e-mail system includes non-time-sensitive information such as crew schedules, supply orders for the ships and their onboard restaurants and snack bars, and other types of administrative traffic. Each of the ships also runs an Oracle database, which holds engineering maintenance data. Judd says he'd eventually like to see these databases updated electronically via the wireless LAN system.

Adapting a system designed for an office campus environment to shipboard use has its limitations, Judd says. The inherently limited range of the system limits the communication time in each port to roughly 90 minutes: The ships usually pick up a signal 20 minutes out from each port, spend 45 to 50 minutes in port and have another 20 minutes of connectivity outbound. The AMHS has also limited the size of attachments ever since someone tried to send all nine ships a file that was so fat that it choked the network.

Despite these limitations, the wireless LAN system emerged as the best choice the AMHS could make, based on a cost/benefit analysis, says Judd. The AMHS considered satellite service, which would have provided continuous communications, but ruled it out due to high costs and low data-speed rates of roughly 2.4K bit/sec. The state also considered adapting high-frequency radios already installed on each ship to handle data, but that offered only 300K bit/sec. and would have required the AMHS to build its own massive, shore-based high-frequency transmitter site.

Other mobile users include FedEx Corp., which plans to equip its delivery fleet with industry standard 802.11b wireless LANs. These networks are designed to dump broadband data (including fat digital signature files) when a truck nears a terminal and automatically senses an access point. Cleveland-based Penske Logistics plans to install wireless LAN hubs on 4,000 trucks that will provide high-speed links to drivers as they unload and scan cargo, with that data pumped into Penske and customer back-end systems when the truck nears a terminal, just as in the FedEx system.

Unlicensed Options

Users in fixed installations have turned to unlicensed wireless LANs to avoid the costs of cabling and desktop hardware, and they're choosing unlicensed wireless ISPs as an alternative to DSL service.

Ed Golebiewski, controller at the Community Health Center in Buffalo, N.Y., says a quick cost/benefit analysis showed that installing a 2.4-GHz wireless LAN from Cisco beat a wired installation when the outpatient clinic moved into a new building last August. The clinic has 25 examination rooms, but a maximum of only 15 doctors are on duty at one time.

"It would have been very expensive to put desktops in all the offices, so I just bought 15 wireless LAN laptops and let the doctors walk around with them," Golebiewski says.

The clinic network hooks into the outside world through another wireless service, a fixed wireless link from Clearwire Technologies Inc. in Arlington, Texas, through its local affiliate, Buffalo-based Meridian LLC.

"They had me up and running in a week. . . . I'm getting 512K bit/sec. up and 256K bit/sec. down. I've done speed tests, and I'm getting my full bandwidth," says Golebiewski.

The clinic operates under strict federal Health Insurance Portability and Accountability Act guidelines, and Golebiewski says his dual wireless system meets the stringent security requirements of that act. And even though both his LAN and his wireless ISP connection operate in the same 2.4-GHz unlicensed band, the clinic "has not experienced any interference problems between the two systems."

Larry Wheeler, a Fort Wayne, Ind.-based communications consultant who has worked with the AMHS, calls unlicensed wireless ISPs "a good substitute for DSL." Equipment costs are five times higher for a licensed wireless system vs. unlicensed, with standard off-the-shelf LAN access points selling for as low as $300 to $500 and PC cards costing as little as $99.

But Wheeler says users need to know the limitations and downsides of unlicensed systems, including the potential for interference in larger cities.

Sooner or later, especially in large metropolitan areas, the 2.4-GHz band could be overwhelmed by the sheer proliferation of wireless LANs and multiple wireless ISPs, says Wheeler. "We're already seeing saturation in certain areas, including Chicago, Los Angeles and New York," he says. When that happens, users will need to seek out other, less-saturated wireless bands, including 5.3 GHz and 5.8 GHz.

CAVU Inc., an Orlando-based wireless ISP that operates under the e-Xpedient trade name, says it has all but eliminated interference problems by operating in the 60-GHz band with equipment developed by Harmonics Corp. in North Andover, Mass.

Unique physical characteristics of that band limit interference but also limit the useful range to approximately three-quarters of a mile vs. approximately 25 miles for the 2.4-GHz band, according to Brian Andrew, president and CEO of CAVU. The company currently offers the 60-GHz service in Miami and plans a gradual major-market roll-out of its system. Andrew says CAVU uses a mesh architecture, in which rooftop receivers communicate with one another and provide customer connectivity. The whole system is connected to a high-speed, Optical Channel 3 point of presence line provided by WorldCom Inc.

The 60-GHz-frequency band provides fiberlike bandwidth, Andrew says. "We guarantee 100M bit/sec. for $100 a month," he says.

Unlicensed fixed wireless installations are already more common than licensed services in the U.S., says Peter Jarich, an analyst at The Strategis Group in Washington. Last year, providers of unlicensed Internet access and phone services had revenues of $44.3 million. Jarich projects that will hit $734.4 million in 2005.

Jarich adds that due to the limitations of unlicensed services and the limited number of markets, "competition on this scale cannot be sustained." But for some users, unlicensed wireless will remain the answer to their data networking needs.

BROADBAND LICENSE-FREE SPECTRUM
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BAND

CURRENT MAXIMUM RAW DATA RATE

FUTURE RAW DATA RATE

902 to 928 MHz1M bit/sec.
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2.4 GHz *11M bit/sec.24M bit/sec. to 54M bit/sec.
5.3 GHz (indoors), 5.8 GHz (outdoors)54M bit/sec. (wireless LAN applications)45M bit/sec. to 100M bit/sec.
60 GHz100M bit/sec.
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* Can be used by wireless LANs or fixed wireless installations for point-to-point service to connect two enterprise locations or point-to-multipoint service used by wireless ISPs. Unlicensed and free for use in North America, Western Europe and parts of Asia.

Copyright © 2001 IDG Communications, Inc.

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