Spread spectrum CDMA subtractive interference canceler system
First Claim
1. A multi-channel, interference canceler for code division multiple access (CDMA) telecommunication systems for use in a communication receiver wherein each channel of the multi-channel, interference canceler comprises:
- a plurality of despreading means, each for despreading a specific CDMA channel to produce a channel signal;
a subtracting means having inputs associated with all but a selected despreading means for outputting an interference reference signal with respect to all despread channels except a selected channel which corresponds to said specific CDMA channel of said selected despreading means; and
means for integrating and combining the channel signal produced by said selected despreading means with said interference reference signal to produce an interference canceled signal.
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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 ith 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 ith channel of the spread-spectrum CDMA signal. The channel correlator or channel-matched filter despreads the subtracted signal.
172 Citations
18 Claims
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1. A multi-channel, interference canceler for code division multiple access (CDMA) telecommunication systems for use in a communication receiver wherein each channel of the multi-channel, interference canceler comprises:
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a plurality of despreading means, each for despreading a specific CDMA channel to produce a channel signal; a subtracting means having inputs associated with all but a selected despreading means for outputting an interference reference signal with respect to all despread channels except a selected channel which corresponds to said specific CDMA channel of said selected despreading means; and means for integrating and combining the channel signal produced by said selected despreading means with said interference reference signal to produce an interference canceled signal. - View Dependent Claims (2, 3, 4)
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5. The multi-channel, interference canceler for code division multiple access (CDMA) telecommunication systems for use in a communication receiver wherein each channel of the multi-channel, interference canceler comprises:
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a plurality of processing means, each for processing a specific CDMA channel; a subtracting means having inputs associated with all but a selected processing means for outputting a subtracted signal; and match means matched to a chip codeword of the specific CDMA channel associated with said selected processing means for filtering said subtracted signal to produce an interference canceled signal of the specific CDMA channel associated with said selected processing means. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A method for reducing interference in a multi-channel, code division multiple access (CDMA) telecommunication system communication receiver comprising the steps of:
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despreading simultaneously a plurality of specific CDMA channels; subtracting all but a selected despread channel of the plurality of channels to produce an interference reference signal; and integrating and combining said selected despread channel with the interference reference signal to produce an interference canceled signal for said selected channel. - View Dependent Claims (13, 14, 15)
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16. A method for reducing interference in a multi-channel, code division multiple access (CDMA) telecommunications system communication receiver comprising the steps of:
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processing a multichannel CDMA signal to produce a plurality of processed signals each processed with a different CDMA channel; subtracting all but a selected one of said plurality of processed signals to produce a subtracted signal; and filtering said subtracted signal with respect to a chip-code associated with the specific CDMA channel corresponding to said selected one of said plurality of processed signals to produce an interference canceled signal for the specific CDMA channel. - View Dependent Claims (17, 18)
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Specification