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Unfulfilled promises

Unfulfilled promises

If you think there's anything simple about wireless networking, think again. There are plenty of carriers and standards, and a fair degree of hardware interoperability. However, you can get either usable speed or wide coverage, but not both. Wireless LAN technologies don't extend far enough, and the wider-ranging wireless communications networks don't offer enough speed and reliability.

Wireless LANs are a terrific idea. They offer a lot of potential for IT managers because they enable the creation of new networks and the expansion of existing ones without the expensive, time-consuming task of pulling cable through walls and floors.

The current standard for wireless Ethernet, 802.11b, offers 11M bit/sec. network connections and reasonably effective security capabilities. The standard, also known as Wi-Fi, is widely used in offices, campuses and homes. Wi-Fi-compliant devices from different makers work well together.

But another new and incompatible wireless Ethernet is on the way. The follow-on standard, 802.11a (yes, b came first), is significantly faster up to 54M bit/sec. This standard uses orthogonal frequency division multiplexing technology, in which the devices determine a set of noninterfering frequencies and then multiplex them and use them in parallel.

This technique may be important for future telephone operations; with the newer standard, network carriers finally have a technology that will let them deliver high-quality service. But 802.11a will be incompatible with 802.11b devices and networks.

Get beyond the LAN level, however, and the wireless freight train slows to a crawl. Forget about megabits per second; what's available are 9.6K bit/sec. cellular-based connections that are too slow and unreliable for business use.

Using wireless carrier networks to access Web-based applications or back-end corporate data can be frustrating, says John Bolz, a systems architect at Wells Fargo & Co. "I wouldn't give my worst enemy an application and expect them to be able to use it on a cell phone," he says. Bolz cites slow speed, poor coverage and latency problems that wreak havoc with application sessions as reasons why the bank may wait for the next generation of cellular technology.

Today's cellular communication networks share bandwidth for voice and data users and suffer from latency issues, spotty coverage, signal dropouts and typical throughput of 9.6K bit/sec. or less.

"Wireless in itself has so many retries due to the physical environment that it overwhelms the actual engineered data rates of the networks," says Don Popowski, technical manager of wireless Internet services at Motient, a wireless communication services firm.

But quality-of-service issues are the biggest problem for users, says Phillip Redman at Gartner. "If you lose bits of data, you can lose the whole transmission," he says.

Speed is the big issue for Michael Murphy, director of IS support services at Carlson Hotels Worldwide. He says he'd like to give executives access to data via Compaq iPaq handhelds and wireless modems but adds that "even 19.2K bit/sec. is slow, by anybody's standards. And if you use a [virtual private network] or data encryption, it really cuts down on performance."

In addition to cellular networks that share data and voice, there are dedicated data networks that focus on e-mail and other low-bandwidth services. These offer a gaggle of competing and noninteroperable services whose availability varies widely by location.

Some wireless telecommunications services are simply circuit-switched cellular networks. Others are digital and support packet-switching but not native TCP/IP. Instead, the protocol rides on top of these systems, separating the application from the underlying transport mechanism and hurting reliability and performance.

Cellular carrier services fall into four basic categories: first-generation (1G) analog technologies, second-generation (2G) digital, and the emerging 2.5G and 3G technologies.

First-generation, analog cellular networks support 9.6K bit/sec. connections using standard modems, but throughput can be as low as 2,400 bit/sec., says Larry Mittag, chief technology officer at mobile systems integrator Stellcom. "Maybe, on a good day, you can get 9,600 [bit/sec.], but you'd better have all the stars right," he says. A rule of thumb is to take a carrier's advertised data rates for any current and future cellular technologies and cut them in half, he says.

Second-generation networks such as Sprint PCS are digital. Throughput is about the same as for 1G networks, but "it relaxes some of the timing so that it won't time out with the latencies that you'll get on a cellular network, and it has better error transmission," says Mittag.

Second-generation technologies include Code Division Multiple Access (CDMA), Cellular Digital Packet Data (CDPD), Global System for Mobile Communications (GSM) and Time Division Multiple Access (TDMA).

2.5G, 3G and Data Networks

The emerging 2.5G technologies boost available bandwidth into the 64K to 144K bit/sec. range and use packet-switching technology, which supports bursts of data traffic more efficiently. For 2.5G networks, there are two primary technologies: general packet radio service (GPRS), and enhanced data rates for GSM and TDMA/136 Evolution (EDGE).

Third-generation wireless communication technologies support data rates of 384K to 2M bit/sec. and beyond. The packet switching is IP-based, making for efficient routing of data from the Internet through the carrier's gateway. The higher bandwidth may allow for better integration of voice, data and video signals.

Unlike 2.5G technologies, which simply provide software updates to existing carrier infrastructures, 3G technologies require new "base station" hardware at each tower. Consequently, the services aren't expected until next year or 2003. The current 3G competitors are wideband CDMA, which blends CDMA and GSM technologies, and Qualcomm Inc.'s CDMA 2000.

Wireless data networks offer an alternative to cellular-based radio. These networks aren't IP-based but are designed to support data. They typically offer good coverage and support low-bandwidth applications such as messaging. They also require the use of proprietary data modems embedded into products such as Research In Motion's BlackBerry devices.

These technologies won't evolve to compete with 2.5G or 3G services, analysts say, but they'll continue to provide a low-cost alternative for low-bandwidth applications. The primary network technologies are Mobitex, DataTAC and Reflex.

Ultimately, 3G technologies should deliver the improved reliability and performance that corporate users need.

"It's going to come down to two technologies: wideband CDMA and CDMA 2000," says Redman. But, he adds, while the technology might start rolling out next year, "we will see islands of coverage. It won't be contiguous like the cellular network is today."

In the meantime, the emerging 2.5G networks may be the best bet. Carson Hotels' Murphy is already eyeing AT&T Wireless Group's 2.5G pilot in Washington. With 2.5G, "we should be able to replicate the dial-up experience," he says.


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