Transmit signal preprocessing based on transmit antennae correlations for multiple antennae systems

• US 7,149,254 B2
• Filed: 09/06/2001
• Issued: 12/12/2006
• Est. Priority Date: 09/06/2001
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Sampath, Hemanth
• Primary Examiner(s): BURD, KEVIN MICHAEL
• Application Number:
  US09/948,204
• Publication Number:
  US 20030043929A1
• Time in Patent Office: 1,923 Days
• Field of Search: 375/267, 375/259, 375/260, 375/146, 375/295, 375/296
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092

Abstract

The present invention provides a method and system for preprocessing transmit signals in spatial multiplexing and diversity systems that include multiple transmit antennae. The method includes generating a representative correlation matrix based upon estimates of a correlation between each pair of the plurality of antennae. An equivalent eigenvalue decomposition of the representative correlation matrix is determined. A preprocessing matrix based upon the equivalent eigenvalue decomposition is generated. Finally, a preprocessor preprocesses the transmit signals by multiplying blocks of data of the transmit signals with the preprocessing matrix. The representative correlation matrix can be an exact estimate of the correlation between each pair of the multiple antennae, or the representative correlation matrix can be an approximate estimate of the correlation between each pair of the multiple antennae.

Claims

1. A method of preprocessing transmit signals of a transmitter having a plurality of antennae, the method comprising:

generating a representative correlation matrix based upon estimates of a correlation between each pair of the plurality of antennae;

determining an equivalent eigenvalue decomposition of the representative correlation matrix;

generating a preprocessing matrix based upon the equivalent eigenvalue decomposition; and

preprocessing the transmit signals by multiplying blocks of data of the transmit signals with the preprocessing matrix, the preprocessing including selecting a number B largest eigenvectors of the representative correlation matrix, where B is a number of data streams received by a preprocessor, generating an orthogonal matrix from the B largest eigenvectors, and multiplying the orthogonal matrix with a scaling matrix to generate the preprocessing matrix.

2. The method of preprocessing signals of claim 1, wherein the representative correlation matrix is based upon a mean estimate of a channel matrix that represents a transmission channel between the plurality of antennae and a receiver.

3. The method of preprocessing signals of claim 1, wherein the representative correlation matrix is based upon a covariance estimate of a channel matrix that represents a transmission channel between the plurality of antennae and a receiver.

4. The method of preprocessing signals of claim 1, further comprising:

generating an eigenvector from the representative correlation matrix.

5. The method of preprocessing signals of claim 1, wherein the data steams received by the preprocessor are generated by a space/time processor.

6. The method of preprocessing signals of claim 5, wherein the space/time processor provides spatial multiplexing.

7. The method of preprocessing signals of claim 1, further comprising:

generating a first orthogonal matrix from the B largest eigenvectors;

generating a minimum distance error matrix from a space/time processor that generates the data streams;

selecting a number B largest minimum distance eigenvectors of the minimum distance error matrix;

generating a second orthogonal matrix from the B largest minimum distance eigenvectors; and

wherein

generating a preprocessing matrix comprises multiplying the first orthogonal matrix with a scaler matrix and the second orthogonal matrix.

8. The method of preprocessing signals of claim 7, wherein the data streams received by the preprocessor are generated by a space/time processor.

9. The method of preprocessing signals of claim 8, wherein the space/time processor that generates the data streams provides transmission diversity.

10. The method of preprocessing signals of claim 1, wherein the representative correlation matrix is an exact estimate of the correlation between each pair of the multiple antennae.

11. The method of preprocessing signals of claim 1, wherein the representative correlation matrix is generated by a receiver that receives the preprocessed transmit signals.

12. The method of preprocessing signals of claim 1, wherein the representative correlation matrix is generated by a transmitter that transmits the preprocessed transmit signals.

13. The method of preprocessing signals of claim 1, wherein the preprocessed transmit signals are modulated with a multi-carrier modulator.

14. The method of preprocessing signals of claim 13, wherein the multi-carrier modulator comprises an orthogonal frequency division multiplexer.

15. The method of preprocessing signals of claim 13, further comprising a plurality of preprocessors, wherein a preprocessor corresponds with at least one of each of a plurality carrier signals of the multi-carrier modulator.

16. The method of preprocessing signals of claim 15, wherein each preprocessing matrix of each of the plurality of preprocessors is based upon a correlation matrix between each pair of the plurality of antennae at a frequency of the corresponding carrier signal.

17. The method of preprocessing signals of claim 1, wherein the transmit signals are formatted according to at least one of the following multiple access schemes:

time division multiple access (TDMA), frequency division multiple access (FDMA), code division multiple access (CDMA), orthogonal frequency division multiple access (OFDMA) and wavelet division multiple access.

18. A system for preprocessing signals to be transmitted from a transmitter having multiple antennae, to a receiver for receiving the preprocessed signals, comprising:

means for generating a representative correlation matrix based upon estimates of a correlation between signal transmitted from each pair of the multiple antennae;

means to determine an equivalent eigenvalue decomposition of the representative correlation matrix;

means to generate a preprocessing matrix based upon the equivalent eigenvalue decomposition, said generating means to select a number B largest eigenvectors of the representative conelation matrix, where B is a number of received data streams, to generate an orthoaonal matrix from the B largest eigenvectors, and to multiply the orthogonal matrix with a scaling matrix to generate the preprocessing matrix; and

a preprocessor for preprocessing the transmit signals by multiplying blocks of data of the transmit signals with the preprocessing matrix.

19. The system for preprocessing signals of claim 18, wherein the receiver comprises a post-processor that comprises at least one of a maximum likelihood receiver, a beam former, an minimum mean square error receiver, a zero forcing receiver.

20. The system for preprocessing signals of claim 18, further comprising multiple preprocessors in which a preprocessor is selected based upon the preprocessing matrix.

21. A system for preprocessing signals to be transmitted from a plurality of transmitters, each transmitter having at least one transmit antenna, to a receiver, comprising:

means to generate a representative correlation matrix based upon estimates of a correlation between signal transmitted from each pair of transmitter antennae;

means to determine an equivalent eigenvalue decomposition of the representative correlation matrix;

means to generate a preprocessing matrix based upon the equivalent eigenvalue decomposition, said generating means to select a number B largest eigenvectors of the representative correlation matrix, where B is a number of received data streams, to generate an orthogonal matrix from the B largest eigenvectors, and to multiply the orthogonal matrix with a scaling matrix to generate the preprocessing matrix; and

a preprocessor within each transmitter to multiply to multiply the blocks of data of the transmit signals with the preprocessing matrix.

22. A method of preprocessing transmit signals of a transmitter, the method comprising:

generating a representative correlation matrix based upon estimates of a correlation between each pair of the plurality of antennae;

generating a preprocessing matrix based upon the representative correlation matrix by selecting a number B largest eigenvectors of the representative correlation matrix, where B is a number of received data streams, generating an orthogonal matrix from the B largest eigenvectors, and multiplying the orthogonal matrix with a scaling matrix to generate the preprocessing matrix; and

a preprocessor preprocessing the transmit signals by multiplying blocks of data of the transmit signals with the preprocessing matrix.

23. The method for preprocessing signals of claim 22, further comprising:

determining an equivalent eigenvalue decomposition of the representative correlation matrix; and

generating the preprocessing matrix based upon the equivalent eigenvalue decomposition.

24. The method of preprocessing signals of claim 23, further comprising:

generating an eigenvector from the representative correlation matrix.

25. An apparatus comprising:

a plurality of anntennae through which the apparatus can transmit signal(s); and

a pre-processor, to generate a preprocessing matrix based, at least in part, upon an equivalent eigenvalue decomposition of a representative correlation matrix between each pair of the plurality of antennae, to select a number B largest eigenvectors of the representative correlation matrix, where B is a number of received data streams, to generate an orthogonal matrix from the B largest eigenvectors, and to multiply the orthoaonal matrix with a scaling matrix to generate the preprocessing matrix, and to process content of one or more received coded signal stream(s) by multiplying the content with the preprocessing matrix to generate one or more signal(s) for transmission via at least a subset of the plurality of antennae.