GPRS PERFORMANCE MUTES BRAGGING RIGHTS

The traditional battle cry that GSM is the superior standard was muted at this year's GSM World Congress because early tests of GPRS have revealed disappointing throughput and latency results.

With only 100,000 GPRS subscribers after the first 12 months, Deutsche Telekom wireless subsidiary T-Mobile is still in the process of evaluation and optimization, said Klaus Juergen Krath, T-Mobile's director of radio access technology. In the voice network, GPRS allows for longer connection holds — even when signal quality diminishes.

But T-Mobile and others have found that “GPRS throughput falls off rapidly when the signal quality fades,” Krath said. This results in an unacceptable number of retransmissions. Further, latency runs to about three minutes when authentication is factored, Krath said.

T-Mobile will continue to optimize its network until it can achieve the desired and much-publicized speeds for data transmission. Meanwhile, Krath advises GPRS carriers, to start early in working with vendors to stabilize the network and handsets, integrate and qualify handset performance, and address performance on the application level during the design phase.

Cingular Wireless, one of the newest GSM carriers, weighed in on the subject of data rates, raising additional questions about its technology choice. “There's a bit of a game being played out on the subject of peak speed,” said Cingular CEO Stephen Carter.

He should know, having just completed evaluation of the technologies. CDMA 1XRTT claims 154 kb/s, GPRS claims 115 kb/s and EDGE predicts 470 kb/s.

“Real-world translations really are about 60 to 80 kb/s for 1XRTT, 40 to 50 kb/s for GPRS and 100 to 150 kb/s for EDGE.”

Again justifying Cingular's GSM technology choice, Carter said the decision was driven by the 30% of subscribers that already use GSM within the networks of BellSouth and SBC Communications, Cingular's parent companies. Once operational, Carter plans to drive adoption by focusing on price and applications — particularly for enterprises.

“Adoption won't be lasting or profitable for carriers unless we have the relevance factor also,” Carter said. “What will drive the mass market are applications that can be used across multiple industries and personal needs such as e-mail, Internet access, location services and entertainment.”

In the meantime, carriers will continue to ramp up performance for long-term goals. T-Mobile's Krath said this experience is providing valuable insight for future universal mobile telecommunications system (UMTS) implementation.

“I'm sure with UMTS, we will face additional challenges. But with this experience, we will get there.”