Time for 3G handset makers to start proper testing - Spirent
Not up to snuff
The 3G phones in the market are not up to snuff, according to experts: "We are seeing performance differences between two 3G terminals, with as much as 6dB or 7 dB falloff in signal sensitivity. Inside a building where signals are marginal, that's the difference between 'working' and 'not working' - and it's not being caught in testing."
The accusation comes from the leader in terminal (phone and handset and data cards, to us users) testing: Spirent. Director of Applications Engineering, Nigel Wright, said frankly: "The handset makers have concentrated on passing 'conformance' tests, at the expense of real-world performance."
Unlike the standard GSM cellphone in Europe a 3G handset is hard to test.
The "time slot" system of sharing antennae on GSM is replaced by a CDMA contention management system, where the number of users on a base station can vary widely.
On Wideband CDMA (3G in Europe is all WCDMA) the critical problem is power management, both in the handset, and in the base station.
"The handset has to manage power, because of the need to maximise battery life," said Wright. "But it's not a simple equation. The more users in a cell, the more power you have to pump into the signal, and the less power you pump in, the more errors users will see on the fringes."
Users of 3G data services will all be well aware of the problems of trying to get error-free communications, especially on data cards. But it's very difficult to set up a good real-world test for phones or data cards which is repeatable, and as a result, the requirements of UMTS "conformance" tests have become very watered down, Spirent thinks.
"We're well aware that a few big handset makers have put pressure on the committees to allow performance which isn't optimised for anything except passing the conformance test," said Wright. "It's a problem which the networks are very concerned about, because users are seeing calls dropped, errors, and loss of signal, which the networks are blamed for. But the problem is in the mobile terminal, in our judgement, in far too many cases."
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