Unitary precoding based on randomized FFT matrices

• US 9,106,287 B2
• Filed: 05/02/2014
• Issued: 08/11/2015
• Est. Priority Date: 10/28/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wang, Jibing, Kadous, Tamer Adel
• Primary Examiner(s): Garcia, Santiago
• Application Number:
  US14/268,999
• Publication Number:
  US 20140247894A1
• Time in Patent Office: 466 Days
• Field of Search: 375/267
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0447 utilizing uniform distribution
• CPC Class Codes: H04B 7/0482 Adaptive codebooks
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601

Abstract

Systems and methodologies are described that facilitate constructing unitary matrices that may be utilized in linear precoding for multiple-input multiple-output (MIMO) wireless communication systems. Each unitary matrix may be generated by combining (e.g., multiplying) a diagonal matrix with a Discrete Fourier Transform (DFT) matrix. The unitary matrices may be utilized to provide feedback related to a channel and/or control transmission over a channel based upon obtained feedback.

Claims

1. A method that facilitates providing channel related feedback for precoding in a wireless communication system, comprising:

using a set of unitary matrices, each of the unitary matrices being generated by a processor based upon a diagonal matrix associated with a random phase and a Discrete Fourier Transform (DFT) matrix;

selecting a particular unitary matrix from the set of unitary matrices based upon an estimate, provided by a feedback evaluator, of a forward link channel; and

transmitting an index associated with the particular unitary matrix via a reverse link channel.

2. The method of claim 1, further comprising generating each of the unitary matrices by multiplying the diagonal matrix by the DFT matrix.

3. The method of claim 1, wherein the DFT matrix is a MT by L matrix, MT is a number of transmit antennas and L is a rank of space-time codes.

4. The method of claim 1, further comprising evaluating

5. The method of claim 1, wherein columns of the DFT matrix are orthonormal.

6. The method of claim 1, further comprising transmitting the set of unitary matrices to a disparate communications apparatus.

7. The method of claim 1, further comprising estimating the forward link channel to yield a channel matrix.

8. The method of claim 7, further comprising effectuating eigen decomposition of the channel matrix to generate a channel unitary matrix.

9. The method of claim 8, selecting the particular unitary matrix further comprises comparing the channel unitary matrix with the set of unitary matrices to identify the particular unitary matrix.

10. The method of claim 1, wherein the set of unitary matrices is substantially similar to a set of unitary matrices employed by a base station to which the index is transmitted.

11. The method of claim 1, wherein the wireless communication system is a multiple-input multiple-output (MIMO) system.

12. The method of claim 1, wherein the wireless communication system is a time division duplex (TDD) system.

13. The method of claim 1, wherein the wireless communication system is a frequency division duplex (FDD) system.

14. A wireless communications apparatus, comprising:

a memory that retains instructions for using a set of unitary matrices, each of the set of unitary matrices based upon a combination of diagonal matrices associated with a random phase and Discrete Fourier Transform (DFT) matrices and yielding channel related feedback, for precoding selected as a particular unitary matrix from the set of unitary matrices based upon an estimate of a forward link channel; and

a processor, coupled to the memory, configured to execute the instructions retained in memory.

15. The wireless communications apparatus of claim 14, wherein the memory further retains instructions for generating the set of unitary matrices by multiplying the diagonal matrices by the DFT matrices.

16. The wireless communications apparatus of claim 14, wherein the diagonal matrices each are associated with a random phase and the DFT matrices each are a MT by L matrix, MT is a number of transmit antennas and L is a rank of space-time codes.

17. The wireless communications apparatus of claim 14, wherein the memory further retains instructions for estimating a forward link channel to yield a channel estimate, selecting a particular unitary matrix for the precoding from the set of unitary matrices based upon the channel estimate, and transmitting an index associated with the particular unitary matrix over a reverse link channel.

18. A wireless communications apparatus that generates unitary matrices and provides channel related feedback for precoding, comprising:

means for using a set of unitary matrices, each of the set of unitary matrices being based upon diagonal matrices associated with a random phase and Discrete Fourier Transform (DFT) matrices;

means for selecting a particular unitary matrix from the set of unitary matrices based upon an estimate of a forward link channel; and

means for transmitting an index associated with the particular unitary matrix via a reverse link channel.

19. The wireless communications apparatus of claim 18, further comprising means for constructing each of the unitary matrices by multiplying a particular diagonal matrix by a corresponding DFT matrix.

20. The wireless communications apparatus of claim 18, further comprising:

means for generating the diagonal matrices;

and means for constructing the DFT matrices.

21. A non-transitory computer-readable medium having stored thereon machine-executable instructions for:

using a set of unitary matrices generated by a processor, each of the unitary matrices being based on a function of a diagonal matrix associated with a random phase and a Discrete Fourier Transform (DFT) matrix;

estimating a forward link channel to yield a channel estimate;

identifying a particular unitary matrix from the set of unitary matrices based upon the channel estimate;

determining an index of the particular unitary matrix selected from the set of unitary matrices; and

transmitting the index via a reverse link channel.

22. The machine-readable medium of claim 21, the machine-executable instructions further comprise multiplying the diagonal matrix by the DFT matrix to yield each of the unitary matrices.

23. In a wireless communication system, an apparatus comprising:

a processor configured to;

use a codebook of unitary matrices, each of the codebook of unitary matrices being based upon diagonal matrices associated with a random phase and Discrete Fourier Transform (DFT) matrices; and

determine a particular unitary matrix to feedback for utilization in precoding based upon an evaluation of a forward link channel provided by a feedback evaluator; and

send an index associated with the particular unitary matrix to a base station via a reverse link channel.