Closing in on broadband wireless: ATM over mobile networks heats up ISS '97

Last month's International Switching Symposium World Congress in Toronto focused on the network of the future, the much anticipated and discussed multimedia pipeline that will provide all telecommunications services.

Although considerable discussion and debate still revolve around how that futuristic network will operate-the mix of fiber and copper, as well as the eventual roles of asynchronous transfer mode, Internet protocol and frame relay in carrying traffic-a common theme emerged from the papers presented on the future of wireless networks.

If the presentations at ISS '97 are accurate windows to the future, ATM will become the vital transport technology for wireless in the coming years. No fewer than 10 technical papers presented at the weeklong conference touched on ATM's role in the evolution of wireless networks.

"When you talk about third generation [wireless], you're talking about multimedia access," said Mark Rau, vice president of American wireless at Northern Telecom and a co-author of one of the papers. "It's closer to CDMA, a packet-type architecture."

Nortel's design incorporates an ATM link between mobile switching centers and the public network (see figure).

The increased adoption of code division multiple access (CDMA) is leading a natural progression toward ATM, Rau said. CDMA earmarks packets of voice or data traffic for certain destinations by digital codes. Those codes allow signals to be properly received and delivered. ATM operates in the same fashion.

"CDMA is becoming more prevalent," Rau said, adding that universal mobile telephone service is CDMA-based. He said the evolution from CDMA to ATM "is about here. It's just a smooth migration."

The main detail to be ironed out, now that many companies are developing ATM applications for wireless, is achieving interoperability among the companies' developments.

"We're all using primary protocols" for ATM over wireless, he said. "We'll have to move to more standardized implementations."

The primary driver for applying ATM in wireless networks is the exponential increase in wireless traffic that is expected to continue for the foreseeable future.

Rau said Nortel's developments to date are primarily driven by expected demand, but discussions with carriers have revealed interest from service providers in such technology.

"We see that the demand is going to be there," Rau said. "We've talked to a few carriers, and it's been well-received."

The demand for broadband wireless services is not expected to come from mobile users, however. ATM over wireless is expected to have the greatest impact in the fledgling fixed wireless market, he said.

"It may be that people will want to add a second line," Rau explained. Those people may choose fixed wireless, he said.

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