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Technology Stocks : Qualcomm Incorporated (QCOM)
QCOM 163.32+2.3%Nov 21 9:30 AM EST
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To: waitwatchwander who wrote (16657)10/16/1998 5:40:00 PM
From: Clarksterh  Read Replies (2) of 152472
 
CDMA-2000, W-CDMA, CDMAOne trimode handsets. Although currently this is not likely to be technologically feasible (I need to really dig into the meat of CDMA-2000 and W-CDMA in order to be able to say with certainty), I'd be surprised if Qualcomm had designed CDMA-2000 such that a CDMAOne phone wouldn't work with it.

The reason is that CDMAOne and WCDMA use different RF (the way the radio waves are modulated and where/what added data is transmitted), IF (e.g. the way the chip'ing is done), and baseband schemes (e.g. voice coding and error correction). A lot of the underlying technology is the same, but the actual standards are quite different. Currently it is possible to do much of the baseband processing in software (since baseband processing involves pretty low frequencies), so you need only one chip and two software packages, but for IF you would probably need a very powerful processor to do the processing in software, which probably isn't practical in a mobile system (although strictly speaking this is somewhat outside my area of expertise). And in RF we just don't have the technology yet. Thus a dual mode phone would probably need at least two separate and fairly sophisticated RF and IF systems. This would make a dual mode phone pretty clunky. (Note that the same is true for dual analog/CDMA phones, but the difference is that analog is so simple that the added hardware doesn't add much space or power consumption.)

Clark

PS Sometime in the next 5 or 10 years it probably will become possible to do everything in software, and at that point dual mode will become trivial, but ... .
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