Spread spectrum CDMA subtractive interference canceler system

Multiplex communications – Crosstalk suppression

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370333, 370335, 370342, 370479, 375206, 375207, 375208, 375343, 375346, 380 34, H04B 1707, H04T 1304

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active

057198527

ABSTRACT:
A spread-spectrum code division multiple access interference canceler for reducing interference in a direct sequence CDMA receiver having N chip-code channels. The interference canceler includes a plurality of correlators or matched filters, a plurality of spread-spectrum-processing circuits, subtracting circuits, and channel correlators or channel-matched filters. Using a plurality of chip-code signals, the plurality of correlators despreads the spread-spectrum CDMA signal as a plurality of despread signals, respectively. The plurality of spread-spectrum-processing circuits uses a timed version of the plurality of chip-code signals, for spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal. For recovering a code channel using an i.sup.th chip-code-signal, the subtracting circuits subtracts from the spread-spectrum CDMA signal, each of the N-1 spread-spectrum-processed-despread signals thereby generating a subtracted signal. The N-1 spread-spectrum-processed-despread signals do not include the spread-spectrum-processed-despread signal of the i.sup.th channel of the spread-spectrum CDMA signal. The channel correlator or channel-matched filter despreads the subtracted signal.

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