Patent US5644592A successfully refreshed from Google Patents.
US5644592A
Expired / Lapsed
US
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Parallel interference cancellation for CDMA applications
Assignee: California Institute of Technology
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Filing: 1995-04-24
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Granted: 1997-07-01
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Expires: 2015-04-24
Abstract
Abstract The present invention provides a method of decoding a spread spectrum composite signal, the composite signal comprising plural user signals that have been spread with plural respective codes, wherein each coded signal is despread, averaged to produce a signal value, analyzed to produce a tentative decision, respread, summed with other respread signals to produce combined interference signals, the method comprising scaling the combined interference signals with a weighting factor to produce a scaled combined interference signal, scaling the composite signal with the weighting factor to produce a scaled composite signal, scaling the signal value by the complement of the weighting factor to produce a leakage signal, combining the scaled composite signal, the scaled combined interference signal and the leakage signal to produce an estimate of a respective user signal.
Inventors
- 👤 Dariush Divsalar
- 👤 Marvin K. Simon
- 👤 Dan Raphaeli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:36
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7097; H04B1/7103; H04B1/7107; H04B1/71075; H04B2001/71077
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
133 words
A method of decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, said method comprising: scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; scaling said composite signal with said weighting factor to produce a scaled composite signal; scaling one of said signal value by the complement of said weighting factor to produce a leakage signal; and combining said scaled composite signal with a scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 2
Independent Claim
133 words
A method of decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, said method comprising: scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; scaling said composite signal with said weighting factor to produce a scaled composite signal; scaling one of said signal value by the complement of said weighting factor to produce a leakage signal; and combining said scaled composite signal with a scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein said weighting factor has a value in the range of greater than zero and less than one.
Claim 4
Independent Claim
149 words
A method of decoding a spread spectrum composite signal in successive stages, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein in each of said stages each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, said method carried out in each of said successive stages comprising: scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; scaling said composite signal with said weighting factor to produce a scaled composite signal; scaling one of said signal values by the complement of said weighting factor to produce a leakage signal; and combining said scaled composite signal with a scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 5
Independent Claim
149 words
A method of decoding a spread spectrum composite signal in successive stages, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein in each of said stages each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, said method carried out in each of said successive stages comprising: scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; scaling said composite signal with said weighting factor to produce a scaled composite signal; scaling one of said signal values by the complement of said weighting factor to produce a leakage signal; and combining said scaled composite signal with a scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 6
Dependent Claim
32 words
The method of claim 3 wherein said weighting factor increases in each of said successive stages so as to reduce the value of said leakage signal in each of said successive stages.
Claim 7
Dependent Claim
43 words
The method of claim 4 wherein said weighting factor increases monotonically from a first value of greater than zero in a first one of said successive stages to a last value of less than one, in a last one of said successive stages.
Claim 8
Independent Claim
198 words
A method of decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, said method comprising a plurality of interference cancellation steps performed in succession, wherein each step comprises the performance for each one of said user signals of the following substeps: despreading said composite signal to produce a despread signal corresponding to each user signal; filtering each despread signal to produce a signal value for each user signal; analyzing each signal value to produce an information signal for each user signal; respreading each information signal to produce an interference signal for each user signal; summing at least the interference signals corresponding to user signals other than said one user signal to produce a combined interference signal; scaling said combined interference signal with a weighting factor to produce a scaled combined interference signal; scaling said composite signal with said weighting factor to produce a scaled composite signal; scaling said signal value by the complement of said weighting factor to produce a leakage signal; and combining said scaled composite signal, said scaled combined interference signal and said leakage signal to produce an estimate of said one user signal.
Claim 9
Independent Claim
198 words
A method of decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, said method comprising a plurality of interference cancellation steps performed in succession, wherein each step comprises the performance for each one of said user signals of the following substeps: despreading said composite signal to produce a despread signal corresponding to each user signal; filtering each despread signal to produce a signal value for each user signal; analyzing each signal value to produce an information signal for each user signal; respreading each information signal to produce an interference signal for each user signal; summing at least the interference signals corresponding to user signals other than said one user signal to produce a combined interference signal; scaling said combined interference signal with a weighting factor to produce a scaled combined interference signal; scaling said composite signal with said weighting factor to produce a scaled composite signal; scaling said signal value by the complement of said weighting factor to produce a leakage signal; and combining said scaled composite signal, said scaled combined interference signal and said leakage signal to produce an estimate of said one user signal.
Claim 10
Dependent Claim
31 words
The method of claim 6 wherein said weighting factor increases in each of said successive cancellation steps whereby reducing the value of said leakage signal in each of said successive steps.
Claim 11
Dependent Claim
45 words
The method of claim 7 wherein said weighting factor increases monotonically from a first value of greater than zero in a first one of said successive cancellation steps to a last value of less than one, in a last one of said successive cancellation steps.
Claim 12
Dependent Claim
17 words
The method of claim 6 wherein said filtering comprises averaging said despread signal over an integration period.
Claim 13
Dependent Claim
16 words
The method of claim 9 wherein said integration period comprises an integer number of bit times.
Claim 14
Dependent Claim
10 words
The method of claim 10 wherein said integer is one.
Claim 15
Dependent Claim
18 words
The method of claim 6 wherein said analyzing comprises processing said signal value by a hard limiting function.
Claim 16
Dependent Claim
17 words
The method of claim 6 wherein said analyzing comprises processing said signal value by a linear function.
Claim 17
Dependent Claim
18 words
The method of claim 6 wherein said analyzing comprises processing said signal value by a hyperbolic tangent function.
Claim 18
Dependent Claim
18 words
The method of claim 6 wherein said analyzing comprises processing said signal value by a null zone function.
Claim 19
Independent Claim
92 words
A method of decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with all other respread signals to produce combined interference signals, comprising: combining a portion of each signal value with one of said combined interference signals and said composite signal to produce an estimate of a respective user signal whereby to preserve information contained in said user signal.
Claim 20
Independent Claim
92 words
A method of decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with all other respread signals to produce combined interference signals, comprising: combining a portion of each signal value with one of said combined interference signals and said composite signal to produce an estimate of a respective user signal whereby to preserve information contained in said user signal.
Claim 21
Dependent Claim
15 words
The method of claim 16 wherein said portion comprises the complement of a weighting factor.
Claim 22
Dependent Claim
23 words
The method of claim 17 wherein said weighting factor has a value in the range of greater than zero and less than one.
Claim 23
Dependent Claim
25 words
The method of claim 16 further wherein said combined interference signals and said composite signal are scaled by a weighting factor prior to said combining.
Claim 24
Independent Claim
138 words
An apparatus for decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, comprising: means for scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; means for scaling said composite signal with said weighting factor to produce a scaled composite signal; means for scaling one of said signal value by the complement of said weighting factor to produce a leakage signal; and means for combining said scaled composite signal with scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 25
Independent Claim
138 words
An apparatus for decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, comprising: means for scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; means for scaling said composite signal with said weighting factor to produce a scaled composite signal; means for scaling one of said signal value by the complement of said weighting factor to produce a leakage signal; and means for combining said scaled composite signal with scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 26
Dependent Claim
23 words
The apparatus of claim 20 wherein said weighting factor has a value in the range of greater than zero and less than one.
Claim 27
Independent Claim
152 words
An apparatus for decoding a spread spectrum composite signal in successive stages, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein in each of said stages each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, each of said successive stages comprising: means for scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; means for scaling said composite signal with said weighting factor to produce a scaled composite signal; means for scaling one of said signal value by the complement of said weighting factor to produce a leakage signal; and means for combining said scaled composite signal with a scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 28
Independent Claim
152 words
An apparatus for decoding a spread spectrum composite signal in successive stages, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein in each of said stages each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with other respread signals to produce combined interference signals, each of said successive stages comprising: means for scaling one of said combined interference signals with a weighting factor to produce a scaled combined interference signal; means for scaling said composite signal with said weighting factor to produce a scaled composite signal; means for scaling one of said signal value by the complement of said weighting factor to produce a leakage signal; and means for combining said scaled composite signal with a scaled combined interference signal and a corresponding leakage signal to produce an estimate of a respective user signal.
Claim 29
Dependent Claim
32 words
The apparatus of claim 22 wherein said weighting factor increases in each of said successive stages so as to reduce the value of said leakage signal in each of said successive stages.
Claim 30
Dependent Claim
43 words
The method of claim 23 wherein said weighting factor increases monotonically from a first value of greater than zero in a first one of said successive stages to a last value of less than one, in a last one of said successive stages.
Claim 31
Independent Claim
208 words
An apparatus for decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, said apparatus comprising a plurality of successive interference cancellation stages, wherein each stage comprises for each one of said user signals: means for despreading said composite signal to produce a despread signal corresponding to each user signal; means for filtering said despread signal to produce a signal value for each user signal; means for analyzing each signal value to produce an information signal for each user signal; means for respreading each information signal to produce an interference signal for each user signal; means for summing at least the interference signals corresponding to user signals other than said one user signal to produce a combined interference signal; means for scaling said combined interference signal with a weighting factor to produce a scaled combined interference signal; means for scaling said composite signal with said weighting factor to produce a scaled composite signal; means for scaling said signal value by the complement of said weighting factor to produce a leakage signal; and means for combining said scaled composite signal, said scaled combined interference signal and said leakage signal to produce an estimate of said one user signal.
Claim 32
Independent Claim
208 words
An apparatus for decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, said apparatus comprising a plurality of successive interference cancellation stages, wherein each stage comprises for each one of said user signals: means for despreading said composite signal to produce a despread signal corresponding to each user signal; means for filtering said despread signal to produce a signal value for each user signal; means for analyzing each signal value to produce an information signal for each user signal; means for respreading each information signal to produce an interference signal for each user signal; means for summing at least the interference signals corresponding to user signals other than said one user signal to produce a combined interference signal; means for scaling said combined interference signal with a weighting factor to produce a scaled combined interference signal; means for scaling said composite signal with said weighting factor to produce a scaled composite signal; means for scaling said signal value by the complement of said weighting factor to produce a leakage signal; and means for combining said scaled composite signal, said scaled combined interference signal and said leakage signal to produce an estimate of said one user signal.
Claim 33
Dependent Claim
31 words
The apparatus of claim 25 wherein said weighting factor increases in each of said successive cancellation stages whereby reducing the value of said leakage signal in each of said successive stages.
Claim 34
Dependent Claim
45 words
The apparatus of claim 26 wherein said weighting factor increases monotonically from a first value of greater than zero in a first one of said successive cancellation steps to a last value of less than one, in a last one of said successive cancellation steps.
Claim 35
Dependent Claim
20 words
The apparatus of claim 25 wherein said filtering means comprises means for averaging said despread signal over an integration period.
Claim 36
Dependent Claim
16 words
The apparatus of claim 28 wherein said integration period comprises an integer number of bit times.
Claim 37
Dependent Claim
10 words
The apparatus of claim 29 wherein said integer is one.
Claim 38
Dependent Claim
21 words
The apparatus of claim 25 wherein said analyzing means comprises means for processing said signal value by a hard limiting function.
Claim 39
Dependent Claim
20 words
The apparatus of claim 25 wherein said analyzing means comprises means for processing said signal value by a linear function.
Claim 40
Dependent Claim
20 words
The apparatus of claim 25 wherein said analyzing means comprises means for processing said signal value by a hyperbolic function.
Claim 41
Dependent Claim
21 words
The apparatus of claim 25 wherein said analyzing means comprises means for processing said signal value by a null zone function.
Claim 42
Independent Claim
96 words
An apparatus for decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with all other respread signals to produce combined interference signals, comprising: a combiner for combining a portion of each signal value with said combined interference signals and said composite signal to produce an estimate of a respective user signal whereby a portion of information contained in said user signal is preserved.
Claim 43
Independent Claim
96 words
An apparatus for decoding a spread spectrum composite signal, said composite signal comprising plural user signals that have been spread with plural respective codes, wherein each user signal is despread, filtered to produce a signal value, analyzed to produce a tentative decision value, respread, summed with all other respread signals to produce combined interference signals, comprising: a combiner for combining a portion of each signal value with said combined interference signals and said composite signal to produce an estimate of a respective user signal whereby a portion of information contained in said user signal is preserved.
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