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Which way to future wireless data?

Which way to future wireless data?

Is there a better route to 3G? There's a debate brewing among some wireless service providers on how best to migrate current infrastructures to support data-oriented 3G services. At the heart of the debate are two migration paths that seek to do the same thing: improve data rates from the current 14.4K bit/sec to 2M bit/sec and higher.

The migration paths are the Code Division Multiple Access (CDMA) 1xrtt standard, which boosts data rates to 144K bit/sec, and the GSM upgrade called General Packet Radio Service (GPRS). GPRS, which is a time division multiple access technology, can run at 171.2K bit/sec when all eight of its time slots are used.

Both CDMA 1xrtt and GPRS are considered interim steps to 3G - typically called 2.5G - because they fall short of the 384K bit/sec support required for any 3G network.

GPRS is deployed in about two-thirds of the countries in the world, and AT&T Wireless and Cingular Wireless are implementing it in the US. Meanwhile, 80 per cent to 90 per cent of the wireless coverage in the US is CDMA-based.

Indeed, the debate may be settled along geographical lines unless a groundswell of compelling applications tips the scales toward one technology over the other.

"All that really matters is what these guys are doing with services," says Larry Swasey, an independent wireless analyst. "Depending on what the subscriber wants, either technology could be fine."

Tom Crook, director of technology research at Sprint, says the company chose to be bullish on CDMA in 1995 because of the value the technology showed in migration to 3G.

"If it's CDMA [1xrtt] or WCDMA, it's still all based on CDMA," he says. "By choosing to go CDMA, we chose to evolve ourselves in an efficient manner to 3G."

Wideband CDMA offers data rates of 384K bit/sec. It is planned for implementation in 2003. Its counterpart in the GSM/GPRS world is Universal Mobile Telecommunications Service.

In addition to the extensive coverage in the US, CDMA is supported in South Korea, Japan and China, Crook says. Crook says getting to 3G via the GPRS route would be too disruptive.

"In order for us to achieve the higher data rates of 144K bit/sec peak with 1xrtt, all we have to do is go into the base station and plug in a card," he says. "In addition, the next 3G 1X release around 2003 will only require us to perform a software upgrade. Those GSM/GPRS network operators will have to turn up new frequencies, another 10 MHz of spectrum just to maintain the customers they've got while they perform the upgrade."

That's not enough to dissuade Cingular. The carrier's decision to go the GSM/GPRS route is based on market share, says Chris Rinne, vice president of technology and product realization for the carrier.

And Rinne disputes allegations that it will be the more expensive way to get to 3G.

"Five hundred million-plus use GSM technology globally," he says. "That's a 70 per cent market share. Couple that with the lower equipment costs, lower handset costs and spectral efficiency, [and] GSM has the better advantage."

Rinne says CDMA networks will also face multifaceted upgrades to get to 3G, even if 3G happens to be based on CDMA technology.

"There are going to be multiple steps with each type of network," he says. "CDMA networks will have 1xrtt upgrades and similar upgrades beyond that."

But the technology question turns out to be moot because the payback comes from the applications and services on those networks, no matter what they're based on, vendors say. Motorola Inc. and L.M. Ericsson Telephone Co. support both technologies.

"You can really do the same types of services with either technology," says Lars Nilsson, general manager for Ericsson. "The decision really comes down to what carriers are offering in terms of bundled services and what kind of global roaming capability you are looking for."

Analyst Swasey concurs.

"It's really just a value judgment," he says. "It depends on where you are and what you're looking for as an end user."


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