Unitary precoding based on randomized FFT matrices

• US 8,760,994 B2
• Filed: 10/26/2006
• Issued: 06/24/2014
• Est. Priority Date: 10/28/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wang, Jibing, Kadous, Tamer
• Primary Examiner(s): HAILE, AWET A
• Application Number:
  US11/553,462
• Publication Number:
  US 20070097856A1
• Time in Patent Office: 2,798 Days
• Field of Search: 370/208, 370/310, 370/334, 375/257, 375/295, 375/347
• US Class Current: 370/208
• 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 controlling transmission in response to feedback in a wireless communication system, comprising:

constructing a set of unitary matrices, each of the unitary matrices being generated based upon a diagonal matrix and a Discrete Fourier Transform (DFT) matrix, wherein the set of unitary matrices includes a first cluster of unitary matrices, the first cluster of unitary matrices including a subset of the set of unitary matrices;

identifying a selected unitary matrix from the constructed set of unitary matrices based upon a received index, wherein the selected unitary matrix corresponds to a channel unitary matrix derived by a mobile device from forward link channel estimations;

determining whether the selected unitary matrix is included in the first cluster of unitary matrices; and

modifying transmission over the forward link channel based upon the selected unitary matrix being included in the first cluster of unitary matrices;

wherein the modifying transmission over the forward link channel further comprises utilizing substantially equal transmission power for each transmit antenna based upon the selected unitary matrix.

2. The method of claim 1, wherein the modifying transmission over the forward link channel includes multiplying the selected unitary matrix by a transmit vector to yield a signal to transmit via the forward link channel.

3. The method of claim 1, wherein the method includes constructing each of the unitary matrices by multiplying the diagonal matrix by the DFT matrix.

4. The method of claim 3, wherein the diagonal matrix is associated with a random phase.

5. The method of claim 4, wherein the DFT matrix is a M_T by L matrix, M_T is a number of transmit antennas and L is a rank of space-time codes.

6. The method of claim 5, wherein the wireless communications system is a multiple-input multiple-output (MIMO) system.

7. The method of claim 4, wherein the random phase is selected from a uniform random variable between 0and 2π

.

8. The method of claim 1, wherein the set of unitary matrices is substantially similar to a set of unitary matrices employed by the mobile device from which the index is received.

9. The method of claim 8, wherein the index corresponds to a unitary matrix selected from the set of unitary matrices employed by the mobile device.

10. The method of claim 1, wherein the wireless communications system is at least one of a time division duplex (TDD) system and a frequency division duplex (FDD) system.

11. The method of claim 1, wherein the method includes effectuating beamforming based upon the selected unitary matrix.

12. The method of claim 1, wherein the set of unitary matrices includes a second cluster of unitary matrices, and wherein the method includes scheduling transmissions to other mobile devices based on the second cluster of matrices in response to a determination that the selected unitary matrix is included in the first cluster of unitary matrices, wherein the second cluster of unitary matrices is distinct from the first cluster of unitary matrices.

13. The method of claim 12, wherein the determination of whether the selected unitary matrix is included in the first cluster of unitary matrices is based on a value of the received index, wherein, when the value of the received index corresponds to a first index value, the selected unitary matrix corresponds to a randomly selected unitary matrix, and wherein, when the value of the received index corresponds to a second index value, the selected unitary matrix identifies one or more transmission beams associated with the first cluster of unitary matrices.

14. A wireless communications apparatus, comprising:

a memory that retains instructions for;

constructing a set of unitary matrices, each of the unitary matrices being generated based upon a diagonal matrix and a Discrete Fourier Transform (DFT) matrix, wherein the set of unitary matrices includes a first cluster of unitary matrices, the first cluster of unitary matrices including a subset of the set of unitary matrices;

identifying a selected unitary matrix from the constructed set of unitary matrices based upon a received index, wherein the selected unitary matrix corresponds to a channel unitary matrix derived by a mobile device from forward link channel estimations;

determining whether the selected unitary matrix is included in the first cluster of unitary matrices; and

modifying transmission over the forward link channel based upon the selected unitary matrix being included in the first cluster of unitary matrices, wherein the controlling transmission includes utilizing substantially equal transmission power for each transmit antenna based upon the selected unitary matrix; 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 includes instructions for multiplying the diagonal matrix by the DFT matrix to yield the unitary matrices, wherein the diagonal matrix is associated with a random phase, and wherein the DFT matrix is a M_T by L matrix, M_T is a number of transmit antennas and L is a rank of space-time codes.

16. A wireless communications apparatus that constructs unitary matrices and controls transmission over a channel, comprising:

means for constructing a set of unitary matrices, each of the unitary matrices being generated based upon a diagonal matrix and a Discrete Fourier Transform (DFT) matrix, wherein the set of unitary matrices includes a first cluster of unitary matrices, the first cluster of unitary matrices including a subset of the set of unitary matrices;

means for identifying a selected unitary matrix from the constructed set of unitary matrices based upon a received index, wherein the selected unitary matrix corresponds to a channel unitary matrix derived by a mobile device from forward link channel estimations;

determining whether the selected unitary matrix is included in the first cluster of unitary matrices; and

means for modifying transmission over the forward link channel based upon the selected unitary matrix being included in the first cluster of unitary matrices;

wherein the means for modifying transmission over the forward link channel utilizes substantially equal transmission power for each transmit antenna based upon the selected unitary matrix.

17. The wireless communications apparatus of claim 16, wherein the means for modifying transmission over the forward link channel is configured to multiply the selected unitary matrix with a transmit vector to yield a signal for transmission over the forward link channel.

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

constructing a set of unitary matrices, each of the unitary matrices being generated based upon a diagonal matrix and a Discrete Fourier Transform (DFT) matrix, wherein the set of unitary matrices includes a first cluster of unitary matrices, the first cluster of unitary matrices including a subset of the set of unitary matrices;

identifying a selected unitary matrix from the constructed set of unitary matrices based upon a received index, wherein the selected unitary matrix corresponds to a channel unitary matrix derived by a mobile device from forward link channel estimations;

determining whether the selected unitary matrix is included in the first cluster of unitary matrices; and

modifying transmission over the forward link channel based upon the selected unitary matrix being included in the first cluster of unitary matrices, wherein the modifying the transmission includes utilizing substantially equal transmission power for each transmit antenna based upon the selected unitary matrix.

19. The machine-readable medium of claim 18, wherein the constructed set of unitary matrices includes N unitary matrices, where N is an integer.

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

a processor configured to;

construct a codebook that includes a set of unitary matrices, each of the unitary matrices being generated based upon a diagonal matrix and a Discrete Fourier Transform (DFT) matrix, wherein the codebook includes a first cluster of unitary matrices, the first cluster of unitary matrices including a subset of the set of unitary matrices;

identify a selected unitary matrix from the constructed set of unitary matrices based upon a received index, wherein the selected unitary matrix corresponds to a channel unitary matrix derived by a mobile device from forward link channel estimations;

determine whether the selected unitary matrix is included in the first cluster of unitary matrices; and

modify transmission over the forward link channel based upon the selected unitary matrix being included in the first cluster of unitary matrices;

wherein the processor configured to modify transmission is further configured to utilize substantially equal transmission power for each transmit antenna based upon the selected unitary matrix.