Soft weighted interference cancellation for CDMA systems
First Claim
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1. A CDMA receiver, comprising:
- an signal-to-interference-and-noise ratio (SINR)-estimation module in a receiver, the SINR estimation module configured for producing a plurality of pre-processed SINR estimates corresponding to a plurality of pre-processed symbol estimates from a received multipath signal,a thresholding module configured for comparing each of the plurality of pre-processed SINR estimates to a predetermined threshold for determining whether to employ a weighted soft decision or a hard decision,a companding module configured for generating the weighted soft decision or the hard decision for each of the plurality of pre-processed symbol estimates,a synthesizer configured for producing a synthesized interference signal from an output of the companding module, wherein the synthesizer comprises a channel emulator configured for providing channel distortions to the synthesized interference signal, anda canceller configured for producing at least one interference-cancelled signal from an output of the channel emulator.
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Abstract
Interference is cancelled from a baseband signal by synthesizing interference from estimated symbols in interfering subchannels. The estimated symbols are hard-coded, soft weighted, or zeroed, depending on the value of an estimated pre-processed signal-to-interference-and-noise ratio (SINR) in each subchannel in order to maximize a post-processed SINR. The estimated pre-processed SINR is obtained from averages of estimated symbol energies and estimated noise variances, or from related statistical procedures.
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Citations
68 Claims
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1. A CDMA receiver, comprising:
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an signal-to-interference-and-noise ratio (SINR)-estimation module in a receiver, the SINR estimation module configured for producing a plurality of pre-processed SINR estimates corresponding to a plurality of pre-processed symbol estimates from a received multipath signal, a thresholding module configured for comparing each of the plurality of pre-processed SINR estimates to a predetermined threshold for determining whether to employ a weighted soft decision or a hard decision, a companding module configured for generating the weighted soft decision or the hard decision for each of the plurality of pre-processed symbol estimates, a synthesizer configured for producing a synthesized interference signal from an output of the companding module, wherein the synthesizer comprises a channel emulator configured for providing channel distortions to the synthesized interference signal, and a canceller configured for producing at least one interference-cancelled signal from an output of the channel emulator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of receiving a CDMA signal, comprising:
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providing for producing in a receiver a plurality of pre-processed SINR estimates corresponding to a plurality of pre-processed symbol estimates from a received multipath signal, providing for comparing each of the plurality of pre-processed SINR estimates to a predetermined threshold for determining whether to employ a weighted soft decision or a hard decision, providing for generating the weighted soft decision or the hard decision for each of the plurality of pre-processed symbol estimates to produce at least one interference-symbol estimate, providing for producing a synthesized interference signal from at least one of the at least one interference-symbol estimate, providing for emulating channel distortions in the synthesized interference signal, and providing for producing at least one interference -cancelled signal from the emulated synthesized interference signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A CDMA receiver, comprising:
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a means for determining a pre-processed SINR estimate for each of a plurality of pre-processed symbol estimates corresponding to a plurality of subchannels, a means for determining whether to use weighted soft decisions or hard decisions for each subchannel, a means for generating at least one interference-symbol estimate, wherein each of the at least one interference-symbol estimate comprises a hard decision or a weighted soft decision of a corresponding pre-processed symbol estimate, and a means for producing an interference-cancelled signal from a received baseband signal and the at least one interference-symbol estimate, wherein the means for producing an interference-cancelled signal comprises a means for producing a synthesized interference signal from the at least one interference-symbol estimate, and wherein the means for producing a synthesized interference signal includes a means for emulating channel distortions in the synthesized interference signal. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A chipset, comprising:
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an SINR-estimation module in a chipset, the SINR-estimation module configured for producing a plurality of pre-processed SINR estimates corresponding to a plurality of pre-processed symbol estimates from a received multipath signal, a thresholding module configured for comparing each of the plurality of pre-processed SINR estimates to a predetermined threshold for determining whether to employ a weighted soft decision or a hard decision, a companding module configured for generating the weighted soft decision or the hard decision for each of the plurality of pre-processed symbol estimates, a synthesizer configured for producing a synthesized interference signal from an output of the companding module, wherein the synthesizer comprises a channel emulator configured for providing channel distortions to the synthesized interference signal, and a canceller configured for producing at least one interference-cancelled signal from an output of the channel emulator. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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56. A handset, comprising:
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an SINR-estimation module in a handset, the SINR-estimation module configured for producing a plurality of pre-processed SINR estimates corresponding to a plurality of pre-processed symbol estimates from a received multipath signal, a thresholding module configured for comparing each of the plurality of pre-processed SINR estimates to a predetermined threshold for determining whether to employ a weighted soft decision or a hard decision, a companding module configured for generating the weighted soft decision or the hard decision for each of the plurality of pre-processed symbol estimates, a synthesizer configured for producing a synthesized interference signal from an output of the companding module, wherein the synthesizer comprises a channel emulator configured for providing channel distortions to the synthesized interference signal, and a canceller configured for producing at least one interference-cancelled signal from an output of the channel emulator. - View Dependent Claims (57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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Specification