Method and apparatus for receiving and decoding communication signals in a CDMA receiver using partial de-correlation
First Claim
1. In a Code Division Multiple Access (CDMA) receiver which utilizes adaptive equalization for minimizing errors between a Direct Sequence Spread Spectrum (DS-SS) signal and a reference signal;
- a method for optimizing convergence rate and minimizing errors in decoding a received signal comprising the steps of;
a) receiving a DS-SS communication signal including at least one near signal, noise, and a desired DS-SS signal, wherein said desired DS-SS signal comprises binary bits coded with a spreading chip sequence;
b) sampling during a bit interval said received DS-SS communication signal at a chip rate to produce received samples, said received samples being correlated with each other;
c) partially de-correlating the received samples by employing a partial orthogonal transformation algorithm;
d) providing a first subspace having a de-correlated segment associated with the desired DS-SS signal and the at least one near signal;
e) providing a second subspace having a correlated segment associated with noise;
f) adaptively and individually equalizing the first subspace to optimize convergence rate and minimize errors; and
g) adaptively and collectively equalizing the second subspace.
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Abstract
In an adaptive CDMA receiver (20), a Direct Sequence Spread Spectrum (DS-SS) received signal and a reference signal are equalized by minimizing the error between them. The received signal includes a desired DS-SS communication signal comprising binary bits coded with spreading chip sequences. The received signal is sampled at a chip rate to produce sampled received signals which are correlated with each other. The received samples are partially de-correlated by employing an orthogonal transformation algorithm to provide de-correlated subspace elements and correlated subspace elements. The adaptive equalization process is based on de-correlated and correlated subspace elements. Tap coefficients of a despreading equalizer (400) are updated for the de-correlated and correlated elements individually and collectively, respectively. This selective updating of tap coefficients provides for fast convergence and minimum error.
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Citations
18 Claims
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1. In a Code Division Multiple Access (CDMA) receiver which utilizes adaptive equalization for minimizing errors between a Direct Sequence Spread Spectrum (DS-SS) signal and a reference signal;
- a method for optimizing convergence rate and minimizing errors in decoding a received signal comprising the steps of;
a) receiving a DS-SS communication signal including at least one near signal, noise, and a desired DS-SS signal, wherein said desired DS-SS signal comprises binary bits coded with a spreading chip sequence; b) sampling during a bit interval said received DS-SS communication signal at a chip rate to produce received samples, said received samples being correlated with each other; c) partially de-correlating the received samples by employing a partial orthogonal transformation algorithm; d) providing a first subspace having a de-correlated segment associated with the desired DS-SS signal and the at least one near signal; e) providing a second subspace having a correlated segment associated with noise; f) adaptively and individually equalizing the first subspace to optimize convergence rate and minimize errors; and g) adaptively and collectively equalizing the second subspace. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- a method for optimizing convergence rate and minimizing errors in decoding a received signal comprising the steps of;
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9. An adaptive code division multiple access (CDMA) receiver which utilizes adaptive equalization by minimizing errors between a Direct Sequence Spread Spectrum (DS-SS) communication signal and a reference signal, comprising:
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means for receiving the DS-SS communication signal, said DS-SS communication signal including at least one near signal, noise, and a desired DS-SS signal, wherein said desired DS-SS signal comprises binary bits coded with spreading chip sequences a despreading means, comprising; sampling means for sampling, during a bit interval, said received DS-SS communication signal at a chip rate to produce received samples, said received samples being correlated with each other; de-correlation means for partially de-correlating the received samples by employing an orthogonal transformation algorithm to provide partial de-correlated elements corresponding to said received samples, the de-correlation means comprising; first means for providing a first subspace having a de-correlated segment associated with the desired DS-SS signal and the at least one near signal; second means for providing a second subspace having a correlated segment associated with noise; first adaptive equalizer means for adaptively and individually equalizing the first subspace to optimize convergence rate; and second adaptive equalizer means for adaptively and collectively equalizing the second subspace; error minimization means responsive to said partially de-correlated elements for minimizing errors between the reference signal and the desired DS-SS communication signal. - View Dependent Claims (10, 11, 12, 13)
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14. In a Code Division Multiple Access (CDMA) receiver which utilizes adaptive equalization for minimizing the error between a received Direct Sequence Spread Spectrum (DS-SS) signal and a reference signal;
- a method for optimizing convergence rate and minimizing the error in decoding the received signal comprising the steps of;
a) receiving a DS-SS communication signal including at least one near signal, noise, and a desired DS-SS signal, wherein said desired DS-SS signal comprises a training sequence having binary bits coded with a spreading chip sequence; b) sampling during a bit interval said received DS-SS communication signal at a chip rate to produce received samples, said received samples being correlated with each other; c) partially de-correlating the received samples by employing a partial orthogonal transformation algorithm; d) providing a first subspace having a de-correlated segment associated with the at least one near signal; e) providing a second subspace having a correlated segment associated with the desired DS-SS signal and the noise; f) adaptively and individually equalizing the first subspace to optimize convergence rate and minimize errors; and g) adaptively and collectively equalizing the second subspace. - View Dependent Claims (15, 16, 17, 18)
- a method for optimizing convergence rate and minimizing the error in decoding the received signal comprising the steps of;
Specification