MANHASSET, N.Y. — A testing study focusing on popular 3G handsets by Signals Research Group (SRG) found dramatic differences in the ability of different phones to reliably make and maintain calls. The study reached that conclusion despite the fact that all of the phones in the reliability tests passed industry-standard conformance testing needed for certification.

The study also looked at the performance of 3G chip sets from Ericsson Mobile Platforms, Icera, Infineon, InterDigital, Motorola, NEC, Nokia and Qualcomm.

Performance throughput results showed major differences in data-rate throughput for various chip sets under real-world, network conditions.'In some cases, the performance difference was in excess of 30 percent of conformance standard specs.

Like the throughput test results, call reliability varied significantly among commercial handsets.'Handsets tested for reliability included the iPhone 3G (pre- and post-firmware fixes), Sony Ericsson, Motorola, LG and RIM's BlackBerry Bold.

SRG's test results were based on results from Spirent's 8100 Mobile Device Test Systems.

Icera rated highest in 10 of 12 scenarios involving more challenging network conditions. A total of 16 scenarios were tested.

"The results clearly illustrate that testing chip set and device performance beyond minimum certification requirements uncovers performance differences which can significantly [affect] a subscriber's satisfaction with a particular device," said Michael Thelander, CEO of Signals Research Group (Oakland, Calif.).

A high-speed packet access (HSPA) performance test measured downlink and uplink data throughput for each chip set at the physical and application layer under a wide range of network conditions. HSPA is a collection of mobile telephony protocols that extend and improve the performance of existing Universal Mobile Telecommunications System protocols.

The test scenarios, based on test specifications from the 3GPP standards body, included various static conditions as well as industry-standard pedestrian- and vehicular-fading conditions, with downlink and uplink throughput tested separately and simultaneously.

An analysis of the HSPA chip set performance benchmark and mobile handset tests is available on SGA's Web site.