07-04-2009, 09:14 PM
CDMA Technology
Abstract :
CDMA was developed by QUALCOMM Incorporated, a company in San Diego, California. QUALCOMM engineers decided to do something different and applied spread spectrum techniques to a multiple access system, which ultimately became CDMA.
In spread spectrum, instead of giving each person a channel, or each group of 3 or 8 people a time slot, CDMA puts everyone in the same channel at the same time.
At first thought, it would seem to be an impossible task to make work, but it does work. The reason it works is explained in the first two words of CDMA, Code Division.
Each user in the system is separated from every other user by a unique digital code. And, to make sure everyone could have one of these codes of their own, engineers designed 4.4 trillion of them into the system specification.
The fact is, each user is provided their own code for the reverse link. On the forward link, a group of codes is available for users of the system. There is a little more digital processing going on here that will be explained in more detail later. For now, once CDMA processing is complete, the information is converted to an RF signal and sent out over the air link.
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