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To: gdichaz who wrote (28312)7/19/2000 10:18:18 AM
From: JohnG  Respond to of 54805
 
Cha2. Ref:Samsung and 5Mbps on 1.25 MHz channel.
Here is a Rocket post that alludes to a technique to achieve 7X more capacity from CDMA.
JohnG

Interesting post from Yahoo! Rocket board re: increase in CDMA capacity. Any one know anything about this?

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CDMA capacity enhancement lyk_666
7/19/00 9:23 am
For the technically inclined, I have been reading recently in the technical journals about some highly
significant potential increases in CDMA capacity. While not part of the Q patent array, it seems to me that
these new ideas, when incorporated into CDMA several years from now, will make the CDMA approach
absolutely unassailable.

In a CDMA cell, the cell site receiver is usually viewed as working on a given mobile transmission, that is,
correlating the desired mobile's code and extracting the voice or data as desired. The other mobile
transmitters in the cell are modeled as though they contributed additional background noise to the system.
The system reaches capacity when the background noise is large enough that the desired signal cannot be
reliably detected for the correlation to work.

The new work reported looks at all the mobile transmissions in the cell, and correlates all of them, using
the cell site's knowledge of all the codes, and then subtracts or cancels the undesired signals. This reduces
the background noise almost to the level of the thermal noise background, the best that can be done. It is
estimated that this will provide an further capacity increase of several-fold (not described very precisely)
over conventional CDMA (like Q's), not possible with any TDMA approach.

The great benefit of this new work is that it acts as though you had increased the bandwidth allocated to
CDMA by a factor of three or four. The price paid for this is intense use of computation in the cell site
receivers, but this should be easily handled in the next few years by the new processors currently under
development.

Hope this is of some interest.