increase in CDMA capacity.
This is not my post ,I copied it from yahoo and thought it interesting,
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CDMA capacity enhancement 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. Q patent array, it seems to me that these new ideas, when incorporated into CDMA , 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 generation by the new processors currently under development"" |
