MIMO RECEIVER AND METHOD FOR BEAMFORMING USING CORDIC OPERATIONS

• US 20070226287A1
• Filed: 12/29/2006
• Published: 09/27/2007
• Est. Priority Date: 03/24/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Lin, Xintian E., Li, Qinghua, Yu, Tein Yow
• Granted Patent: US 7,649,955 B2
• Time in Patent Office: Days
• US Class Current: 708/490
• CPC Class Codes: G06F 17/16 Matrix or vector computation , e.g. matrix-matrix or matrix-vector multiplication, matrix factorization matrix transposition G06F7/78
• CPC Class Codes: G06F 7/4818 using coordinate rotation digital computer [CORDIC]
• CPC Class Codes: H04B 7/0478 Special codebook structures directed to feedback optimisation
• CPC Class Codes: H04B 7/0663 using vector or matrix manipulations
• CPC Class Codes: H04L 25/0248 Eigen-space methods

Abstract

Embodiments of a MIMO receiver and method for beamforming using CORDIC operations are generally described herein. Other embodiments may be described and claimed. In some embodiments, complex singular value decomposition (SVD) operations are performed on a channel matrix using CORDIC operations to generate vector elements of a beamforming matrix. An inner product of a first of the vector elements and each of a plurality of stored codewords is computed using CORDIC operations. A recursive dimensional reduction on the beamforming matrix is performed based on the quantized first vector element is performed using CORDIC operations. In some embodiments, the MIMO receiver includes reprogrammable CORDIC circuitry.

Claims

1. A method for beamforming in a multiple-input multiple-output (MIMO) wireless communication system comprising:

performing complex singular value decomposition (SVD) operations on a channel matrix using CORDIC operations to generate vector elements of a beamforming matrix;

computing an inner product of a first of the vector elements and each of a plurality of stored codewords using CORDIC operations to provide a quantized first vector element; and

performing a recursive dimensional reduction on the beamforming matrix based on the quantized first vector element using CORDIC operations to quantize remaining vector elements of the beamforming matrix as codewords,

wherein the codewords used to compute the inner products are in a non-vector form comprising a series of rotation angles allowing the CORDIC operations to be performed during the inner product computations.

2. The method of claim 1 wherein the complex SVD operations are performed by one or more of a plurality of CORDIC elements,

wherein the inner product is computed by the one or more CORDIC elements,

wherein the recursive dimensional reduction is performed by the one or more CORDIC elements, and

wherein the CORDIC operations comprise complex phase rotations and Given'"'"'s rotations.

3. The method of claim 1 wherein the codewords are stored in the non-vector form as a series of complex phase rotations and Given'"'"'s rotations, and

wherein the method further comprises storing the codewords in the non-vector form as the series of complex phase rotations and Given'"'"'s rotations prior to the inner product computations.

4. The method of claim 3 further comprising decomposing each of a plurality of vector codewords of a vector codebook into the series of complex phase rotations and Given'"'"'s rotations using CORDIC operations performed by one or more of a plurality of CORDIC elements.

5. The method of claim 1 further comprising quantizing the first vector element with one of the codewords, and

wherein the recursive dimensional reduction performed on the beamforming matrix includes performing a unitary operation with the quantized first vector element using CORDIC operations and a recursive quantization in a lower dimension.

6. The method of claim 1 wherein the CORDIC operations performed for computing the inner products comprises an identification of one or more of the codewords for use in generation of beamforming coefficients at a transmitting station.

7. The method of claim 1 wherein performing the complex SVD operations comprises zeroing-out off-diagonal elements of the channel matrix in an iterative manner by performing CORDIC operations to generate the beamforming matrix.

8. The method of claim 7 wherein the zeroing-out the off-diagonal elements comprises zeroing-out off-diagonal elements of 2×

2 submatrices of the channel matrix in an iterative manner.

9. The method of claim 1 wherein when the channel matrix is a non-square matrix, and

wherein the complex SVD operations include performing a QR decomposition on the channel matrix by applying complex phase rotations and Given'"'"'s rotations using CORDIC operations to zero-out preselected elements of the channel matrix to generate an R matrix and to perform SVD operations on the R matrix to determine the beamforming matrix.

10. A multiple-input multiple-output (MIMO) receiver comprising reprogrammable CORDIC circuitry comprising a plurality of CORDIC elements to perform complex singular value decomposition (SVD) operations on a channel matrix using CORDIC operations to generate vector elements of a beamforming matrix, compute an inner product of a first of the vector elements and each of a plurality of stored codewords using CORDIC operations to provide a quantized first vector element, and perform a recursive dimensional reduction on the beamforming matrix based on the quantized first vector element using CORDIC operations to quantize remaining vector elements of the beamforming matrix as codewords,

wherein the codewords used to compute the inner products are in a non-vector form comprising a series of rotation angles allowing the CORDIC operations to be performed during the inner product computations.

11. The MIMO receiver of claim 10 wherein the CORDIC operations performed by the reprogrammable CORDIC circuitry comprise complex phase rotations and Given'"'"'s rotations, and

wherein the MIMO receiver further comprises a controller to:

reconfigure the CORDIC circuitry to initially generate the codewords represented as a series of complex phase rotations and Given'"'"'s rotations; and

reconfigure the CORDIC circuitry to perform the complex SVD operations, compute the inner product and perform the recursive dimensional reduction.

12. The MIMO receiver of claim 11 wherein the reprogrammable CORDIC circuitry is reconfigured to decompose each of a plurality of vector codewords of a vector codebook into the series of complex phase rotations and Given'"'"'s rotations using CORDIC operations performed by one or more of the CORDIC elements.

13. The MIMO receiver of claim 10 wherein the reprogrammable CORDIC circuitry is reconfigured to quantize the first vector element with one of the codewords, and

wherein the recursive dimensional reduction performed on the beamform matrix includes configuring the reprogrammable CORDIC circuitry to perform a unitary operation with the quantized vector element using CORDIC operations and a recursive quantization in a lower dimension.

14. The MIMO receiver of claim 10 wherein the reprogrammable CORDIC circuitry is reconfigured to compute the inner products using CORDIC operations to identify one or more of the codewords for use in generation of beamforming coefficients at a transmitting station.

15. The MIMO receiver of claim 10 wherein the reprogrammable CORDIC circuitry is reconfigured to zero-out off-diagonal elements of the channel matrix in an iterative manner by performing CORDIC operations to generate the beamforming matrix.

16. The MIMO receiver of claim 10 wherein when the channel matrix is a non-square matrix, and

wherein the reprogrammable CORDIC circuitry is reconfigured to perform the complex SVD operations by performing a QR decomposition on the channel matrix by applying complex phase rotations and Given'"'"'s rotations using CORDIC operations to zero-out preselected elements of the channel matrix to generate an R matrix and to perform SVD operations on the R matrix to determine the beamforming matrix.

17. A receiver system comprising:

two or more receive signal paths to receive signals through two or more antennas;

a channel estimator to generate a channel matrix from the received signals; and

reprogrammable CORDIC circuitry comprising a plurality of CORDIC elements to perform complex singular value decomposition (SVD) operations on the channel matrix using CORDIC operations to generate vector elements of a beamforming matrix, compute an inner product of a first of the vector elements and each of a plurality of stored codewords using CORDIC operations to provide a quantized first vector element, and perform a recursive dimensional reduction on the beamforming matrix based on the quantized first vector element using CORDIC operations to quantize remaining vector elements of the beamforming matrix as codewords,

wherein the codewords used to compute the inner products are in a non-vector form comprising a series of rotation angles allowing the CORDIC operations to be performed during the inner product computations.

18. The receiver system of claim 17 wherein the CORDIC operations performed by the reprogrammable CORDIC circuitry comprise complex phase rotations and Given'"'"'s rotations, and

wherein the receiver further comprises a controller to:

reconfigure the CORDIC circuitry to initially generate the codewords represented as a series of complex phase rotations and Given'"'"'s rotations; and

reconfigure the CORDIC circuitry to perform the complex SVD operations, compute the inner product and perform the recursive dimensional reduction.

19. The receiver system of claim 18 wherein the reprogrammable CORDIC circuitry is reconfigured to decompose each of a plurality of vector codewords of a vector codebook into the series of complex phase rotations and Given'"'"'s rotations using CORDIC operations performed by one or more of the CORDIC elements.