Spread spectrum CDMA subtractive interference canceler system
First Claim
1. A method of receiving spread spectrum channel signals within a spread spectrum signal comprising:
- a) despreading a received spread spectrum signal for each of a plurality of specific CDMA channels to produce a first estimate for each channel;
b) for each channel, despreading the estimate obtained from the prior step for all other channels to produce despread other channel signals and subtracting the despread other channel signals from the received signal and despreading the result to produce a next estimate for each channel;
c) repeating step b a selected number of times; and
d) using the estimates for each channel produced by steps a, b and c to output a channel signal for each channel.
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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-processing-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.
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Citations
16 Claims
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1. A method of receiving spread spectrum channel signals within a spread spectrum signal comprising:
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a) despreading a received spread spectrum signal for each of a plurality of specific CDMA channels to produce a first estimate for each channel;
b) for each channel, despreading the estimate obtained from the prior step for all other channels to produce despread other channel signals and subtracting the despread other channel signals from the received signal and despreading the result to produce a next estimate for each channel;
c) repeating step b a selected number of times; and
d) using the estimates for each channel produced by steps a, b and c to output a channel signal for each channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A receiver for receiving spread spectrum channel signals within a spread spectrum signal comprising:
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means for despreading a received spread spectrum signal for each of a plurality of specific CDMA channels to produce a first estimate of a series of estimates for each channel;
means for producing remaining estimates of the series for each channel by repeating a selected number of times, despreading a previous estimate for all other channels to produce despread other channels signals and subtracting the despread other channel signals from the received signal and despreading the result to produce a next estimate for each channel; and
means using the series of estimates for each channel for outputting a channel signal for each channel. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification