Spread spectrum CDMA subtractive interference canceler and method

Claim 2

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of means for generating a plurality of chip-code signals; a plurality of despreading means, with each of said despreading means responsive to the respective distinct chip-code signal identifying a corresponding one of the N channels, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of means for timing the plurality of chip-code signals thereby generating a timed version of the plurality of chip-code signals, respectively; a plurality of means, responsive to the timed version of the plurality of chip-code-signals, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal; means, for an i th chip-code signal, for subtracting from the spread-spectrum CDMA signal, simultaneously, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed-despread signal of the i th despread signal, thereby generating a subtracted signal; and channel means for despreading the subtracted signal with the i th chip-code signal as an i th channel.

Claim 3

The spread-spectrum CDMA interference canceler as set forth in claim 1 wherein each of said plurality of despreading means includes: a filter; a chip-code generator for generating a chip-code signal from a respective chip codeword; and a mixer coupled between said filter and said chip-code generator.

Claim 4

The spread-spectrum CDMA interference canceler as set forth in claim 1 wherein each of said plurality of despreading means includes a matched filter having an impulse response matched to a respective chip codeword.

Claim 5

The spread-spectrum CDMA interference canceler as set forth in claim 1 wherein said channel-despreading means includes: a filter; a chip-code generator for generating a chip-code signal from a chip codeword corresponding to the i th channel; and a mixer coupled between said filter and said chip-code generator.

Claim 6

The spread-spectrum CDMA interference canceler as set forth in claim 2 wherein said channel-despreading means includes: a filter; a chip-code generator for generating a chip-code signal from a chip codeword corresponding to the i th channel; and a mixer coupled between said filter and said chip-code generator.

Claim 7

The spread-spectrum CDMA interference canceler as set forth in claim 3 wherein said channel-despreading means includes: a filter; a chip-code generator for generating a chip-code signal from a chip codeword corresponding to the i th channel; and a mixer coupled between said filter and said chip-code generator.

Claim 8

The spread-spectrum CDMA interference canceler as set forth in claim 3 wherein said channel-despreading means includes a matched filter having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 9

The spread-spectrum CDMA interference canceler as set forth in claim 1 wherein each of said despreading means includes a digital signal processor with digital matched filter having an impulse response matched to a respective chip codeword.

Claim 10

The spread-spectrum CDMA interference canceler as set forth in claim 8 wherein said channel-despreading means includes a matched filter having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 11

The spread-spectrum CDMA interference canceler as set forth in claim 1 wherein said channel-despreading means includes a digital signal processor with digital matched filter having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 12

The spread-spectrum CDMA interference canceler as set forth in claim 8 wherein said channel-despreading means includes a surface acoustic wave (SAW) device having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 13

The spread-spectrum CDMA interference canceler as set forth in claim 1 wherein each of said plurality of despreading means includes a surface acoustic wave (SAW) device having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 14

The spread-spectrum CDMA interference canceler as set forth in claim 12 wherein said channel-despreading means includes a matched filter having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 15

The spread-spectrum CDMA interference canceler as set forth in claim 12 wherein said channel-despreading means includes a chip-code generator for generating a chip-code signal from a digital matched filter having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 16

The spread-spectrum CDMA interference canceler as set forth in claim 12 wherein said channel-despreading means includes a surface acoustic wave (SAW) device having an impulse response matched to a chip codeword corresponding to the i th channel.

Claim 17

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators for delaying the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal; a subtractor, for an i th chip-code signal, for subtracting from the spread-spectrum CDMA signal, simultaneously, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed despread signal of the i th despread signal, thereby generating a subtracted signal; and a channel correlator for despreading the subtracted signal with the i th chip-code signal as an i th channel.

Claim 18

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators for delaying the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal; a subtractor, for an i th chip-code signal, for subtracting from the spread-spectrum CDMA signal, simultaneously, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed despread signal of the i th despread signal, thereby generating a subtracted signal; and a channel correlator for despreading the subtracted signal with the i th chip-code signal as an i th channel.

Claim 19

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N chip-code channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of matched filters, responsive to a plurality of distinct chip-code signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal; a subtractor, for an i th chip-code signal, for subtracting from the spread-spectrum CDMA signal, simultaneously, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed despread signal of the i th despread signal, thereby generating a subtracted signal; and a channel matched filter for despreading the subtracted signal with the i th chip-code-signal as an i th channel.

Claim 20

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N chip-code channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of matched filters, responsive to a plurality of distinct chip-code signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal; a subtractor, for an i th chip-code signal, for subtracting from the spread-spectrum CDMA signal, simultaneously, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed despread signal of the i th despread signal, thereby generating a subtracted signal; and a channel matched filter for despreading the subtracted signal with the i th chip-code-signal as an i th channel.

Claim 23

The method as set forth in claim 18 wherein the first step of despreading includes the step of correlating the spread-spectrum CDMA signal as a plurality of despread signals.

Claim 24

The method as set forth in claim 18 wherein the first step of despreading includes the step of matched filtering the spread-spectrum CDMA signal as a plurality of despread signals.

Claim 27

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators for delaying the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a plurality of subtractors, each of said plurality of subtractors for subtracting from the spread-spectrum CDMA signal all but a particular one of the N spread-spectrum-processed-despread signals, with the particular one of the N spread-spectrum-processed-despread signals being different for each of said plurality of subtractors, thereby generating a plurality of subtracted signals; and a plurality of channel correlators for despreading the plurality of subtracted signals with a particular one of the plurality of chip-code signals, respectively, as a plurality of channels.

Claim 28

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators for delaying the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a plurality of subtractors, each of said plurality of subtractors for subtracting from the spread-spectrum CDMA signal all but a particular one of the N spread-spectrum-processed-despread signals, with the particular one of the N spread-spectrum-processed-despread signals being different for each of said plurality of subtractors, thereby generating a plurality of subtracted signals; and a plurality of channel correlators for despreading the plurality of subtracted signals with a particular one of the plurality of chip-code signals, respectively, as a plurality of channels.

Claim 29

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators for delaying the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a first subtractor, for subtracting from the spread-spectrum CDMA signal, all but a first one of the N spread-spectrum-processed-despread signals, thereby generating a first subtracted signal; a second subtractor, for subtracting from the spread-spectrum CDMA signal, all but a second one of the N spread-spectrum-processed-despread signals, thereby generating a second subtracted signal; and an n th subtractor, for subtracting from the spread-spectrum CDMA signal, all but an n th one of the N spread-spectrum-processed-despread signals, thereby generating an n th subtracted signal; a first channel correlator for despreading the first subtracted signal with a first chip-code signal as an estimate of a first channel; a second channel correlator for despreading the second subtracted signal with a second chip-code signal as an estimate of a second channel; and an n th channel correlator for despreading the n th subtracted signal with an n th chip-code signal as an estimate of an n th channel.

Claim 30

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators for delaying the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a first subtractor, for subtracting from the spread-spectrum CDMA signal, all but a first one of the N spread-spectrum-processed-despread signals, thereby generating a first subtracted signal; a second subtractor, for subtracting from the spread-spectrum CDMA signal, all but a second one of the N spread-spectrum-processed-despread signals, thereby generating a second subtracted signal; and an n th subtractor, for subtracting from the spread-spectrum CDMA signal, all but an n th one of the N spread-spectrum-processed-despread signals, thereby generating an n th subtracted signal; a first channel correlator for despreading the first subtracted signal with a first chip-code signal as an estimate of a first channel; a second channel correlator for despreading the second subtracted signal with a second chip-code signal as an estimate of a second channel; and an n th channel correlator for despreading the n th subtracted signal with an n th chip-code signal as an estimate of an n th channel.

Claim 31

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of matched filters, responsive to a plurality of distinct chip-code-signals, for despreading, simultaneously, a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating, simultaneously, a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a plurality of subtractors, each of said plurality of subtractors for subtracting from the spread-spectrum CDMA signal all but a particular one of the N spread-spectrum-processed-despread signals, with the particular one of the N spread-spectrum-processed-despread signals being different for each of said plurality of subtractors, thereby generating a plurality of subtracted signals; and a plurality of channel-matched filters for despreading the plurality of subtracted signals with a particular one of the plurality of distinct chip-code signals, respectively, as a plurality of channels.

Claim 32

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of matched filters, responsive to a plurality of distinct chip-code-signals, for despreading, simultaneously, a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating, simultaneously, a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a plurality of subtractors, each of said plurality of subtractors for subtracting from the spread-spectrum CDMA signal all but a particular one of the N spread-spectrum-processed-despread signals, with the particular one of the N spread-spectrum-processed-despread signals being different for each of said plurality of subtractors, thereby generating a plurality of subtracted signals; and a plurality of channel-matched filters for despreading the plurality of subtracted signals with a particular one of the plurality of distinct chip-code signals, respectively, as a plurality of channels.

Claim 33

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of matched filters, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating, simultaneously, a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a first subtractor, for subtracting from the spread-spectrum CDMA signal, all but a first one of the N spread-spectrum-processed-despread signals, thereby generating a first subtracted signal; a second subtractor, for subtracting from the spread-spectrum CDMA signal, all but a second one of the N spread-spectrum-processed-despread signals, thereby generating a second subtracted signal; and an n th subtractor, for subtracting from the spread-spectrum CDMA signal, all but an n th one of the N spread-spectrum-processed-despread signals, thereby generating an n th subtracted signal; a first channel-matched filter for despreading the first subtracted signal with a first chip-code signal as an estimate of a first channel; a second channel-matched filter for despreading the second subtracted signal with a second chip-code signal as an estimate of a second channel; and an n th channel-matched filter for despreading the n th subtracted signal with an n th chip-code signal as an estimate of an n th channel.

Claim 34

A spread-spectrum code division multiple access (CDMA) interference canceler for reducing interference in a spread-spectrum CDMA receiver having N channels, with each of the N channels identified by a distinct chip-code signal, comprising: a plurality of matched filters, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating, simultaneously, a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a first subtractor, for subtracting from the spread-spectrum CDMA signal, all but a first one of the N spread-spectrum-processed-despread signals, thereby generating a first subtracted signal; a second subtractor, for subtracting from the spread-spectrum CDMA signal, all but a second one of the N spread-spectrum-processed-despread signals, thereby generating a second subtracted signal; and an n th subtractor, for subtracting from the spread-spectrum CDMA signal, all but an n th one of the N spread-spectrum-processed-despread signals, thereby generating an n th subtracted signal; a first channel-matched filter for despreading the first subtracted signal with a first chip-code signal as an estimate of a first channel; a second channel-matched filter for despreading the second subtracted signal with a second chip-code signal as an estimate of a second channel; and an n th channel-matched filter for despreading the n th subtracted signal with an n th chip-code signal as an estimate of an n th channel.