Multiple-input multiple-output (MIMO) transmission with rank-dependent precoding

• US 8,503,567 B2
• Filed: 07/25/2011
• Issued: 08/06/2013
• Est. Priority Date: 02/09/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kim, Byoung-Hoon, Xu, Hao
• Primary Examiner(s): Torres, Juan A
• Application Number:
  US13/190,160
• Publication Number:
  US 20110280342A1
• Time in Patent Office: 743 Days
• Field of Search: 375/267, 455/132
• US Class Current: 375/267
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

Techniques for performing rank-dependent precoding for a Mulitple-Input Multiple-Output (MIMO) transmission are described. Each rank may be associated with a set of at least one precoding vector or matrix that can provide good performance for that rank. A transmitter may obtain a precoding vector for a rank-1 transmission from a first set containing at least one column vector of a unitary matrix, e.g., a Fourier matrix. The transmitter may perform precoding for the rank-1 transmission based on the precoding vector. The transmitter may obtain a precoding matrix for a rank-2 transmission from a second set containing an identity matrix. The transmitter may perform precoding for the rank-2 transmission based on the precoding matrix. For the rank-2 transmission, the transmitter may select the identity matrix as the precoding matrix if a MIMO channel resembles a diagonal channel (which may be determined based on antenna configurations) and may select the unitary matrix otherwise.

Claims

1. An apparatus for wireless communication, comprising:

at least one processor configured to receive a rank-1 transmission sent from multiple transmit antennas with a precoding vector selected from a first set comprising at least one column vector of a unitary matrix, to process the rank-1 transmission to recover a data stream sent in the rank-1 transmission, to receive a rank-2 transmission sent from the multiple transmit antennas with a precoding matrix selected from a second set comprising an identity matrix, and to process the rank-2 transmission to recover two data streams sent in the rank-2 transmission; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the at least one processor is configured to derive a spatial filter vector for the rank-1 transmission based on the precoding vector, and to perform detection for the rank-1 transmission based on the spatial filter vector.

3. The apparatus of claim 1, wherein the at least one processor is configured to derive a spatial filter matrix for the rank-2 transmission based on the precoding matrix, and to perform Mulitple-Input Multiple-Output (MIMO) detection for the rank-2 transmission based on the spatial filter matrix.

4. The apparatus of claim 1, wherein the at least one processor is configured to perform linear minimum mean square error (MMSE) detection for the rank-2 transmission.

5. The apparatus of claim 1, wherein the at least one processor is configured to perform linear minimum mean square error with successive interference cancellation (MMSE-SIC) detection for the rank-2 transmission.

6. The apparatus of claim 1, wherein the at least one processor is configured to evaluate at least one vector in the first set and at least one matrix in the second set based on a metric, to select a vector or a matrix with best metric, and to send feedback information comprising the selected vector or matrix.

7. A method for wireless communication, comprising:

receiving a rank-1 transmission sent from multiple transmit antennas with a precoding vector selected from a first set comprising at least one column vector of a unitary matrix;

processing the rank-1 transmission to recover a data stream sent in the rank-1 transmission;

receiving a rank-2 transmission sent from the multiple transmit antennas with a precoding matrix selected from a second set comprising an identity matrix; and

processing the rank-2 transmission to recover two data streams sent in the rank-2 transmission.

8. The method of claim 7, wherein the processing the rank-1 transmission comprises:

deriving a spatial filter vector for the rank-1 transmission based on the precoding vector, and

performing detection for the rank-1 transmission based on the spatial filter vector.

9. The method of claim 7, wherein the processing the rank-2 transmission comprises:

deriving a spatial filter matrix for the rank-2 transmission based on the precoding matrix, and

performing Mulitple-Input Multiple-Output (MIMO) detection for the rank-2 transmission based on the spatial filter matrix.

10. The method of claim 7, wherein the processing the rank-2 transmission comprises performing linear minimum mean square error (MMSE) detection.

11. The method of claim 7, wherein the processing the rank-2 transmission comprises performing linear minimum mean square error with successive interference cancellation (MMSE-SIC) detection.

12. The method of claim 7, further comprising:

evaluating at least one vector in the first set and at least one matrix in the second set based on a metric;

selecting a vector or a matrix with best metric; and

sending feedback information comprising the selected vector or matrix.

13. An apparatus for wireless communication, comprising:

means for receiving a rank-1 transmission sent from multiple transmit antennas with a precoding vector selected from a first set comprising at least one column vector of a unitary matrix;

means for processing the rank-1 transmission to recover a data stream sent in the rank-1 transmission;

means for receiving a rank-2 transmission sent from the multiple transmit antennas with a precoding matrix selected from a second set comprising an identity matrix; and

means for processing the rank-2 transmission to recover two data streams sent in the rank-2 transmission.

14. The apparatus of claim 13, wherein the means for processing the rank-1 transmission comprises:

means for deriving a spatial filter vector for the rank-1 transmission based on the precoding vector, and

means for performing detection for the rank-1 transmission based on the spatial filter vector.

15. The apparatus of claim 13, wherein the means for processing the rank-2 transmission comprises:

means for deriving a spatial filter matrix for the rank-2 transmission based on the precoding matrix, and

means for performing Mulitple-Input Multiple-Output (MIMO) detection for the rank-2 transmission based on the spatial filter matrix.

16. The apparatus of claim 13, wherein the means for processing the rank-2 transmission comprises means for performing linear minimum mean square error (MMSE) detection.

17. The apparatus of claim 13, wherein the means for processing the rank-2 transmission comprises means for performing linear minimum mean square error with successive interference cancellation (MMSE-SIC) detection.

18. The apparatus of claim 13, further comprising:

means for evaluating at least one vector in the first set and at least one matrix in the second set based on a metric;

means for selecting a vector or a matrix with best metric; and

means for sending feedback information comprising the selected vector or matrix.

19. A non-transitory machine-readable medium comprising instructions which, when executed by a machine, cause the machine to perform operations including:

receiving a rank-1 transmission sent from multiple transmit antennas with a precoding vector selected from a first set comprising at least one column vector of a unitary matrix;

processing the rank-1 transmission to recover a data stream sent in the rank-1 transmission;

receiving a rank-2 transmission sent from the multiple transmit antennas with a precoding matrix selected from a second set comprising an identity matrix; and

processing the rank-2 transmission to recover two data streams sent in the rank-2 transmission.

20. The non-transitory machine-readable medium of claim 19, wherein the instructions for processing the rank-1 transmission comprises further comprise instructions for:

deriving a spatial filter vector for the rank-1 transmission based on the precoding vector, and

performing detection for the rank-1 transmission based on the spatial filter vector.

21. The non-transitory machine-readable medium of claim 19, wherein the instructions for processing the rank-2 transmission comprises further comprise instructions for:

deriving a spatial filter matrix for the rank-2 transmission based on the precoding matrix, and

performing Mulitple-Input Multiple-Output (MIMO) detection for the rank-2 transmission based on the spatial filter matrix.

22. The non-transitory machine-readable medium of claim 19, wherein the instructions for processing the rank-2 transmission comprises further comprise instructions for performing linear minimum mean square error (MMSE) detection.

23. The non-transitory machine-readable medium of claim 19, wherein the instructions for processing the rank-2 transmission comprises further comprise instructions for performing linear minimum mean square error with successive interference cancellation (MMSE-SIC) detection.

24. The non-transitory machine-readable medium of claim 19, further comprising instructions for:

evaluating at least one vector in the first set and at least one matrix in the second set based on a metric;

selecting a vector or a matrix with best metric; and

sending feedback information comprising the selected vector or matrix.