Adaptive Precoding Codebooks for Wireless Communications

• US 20100238913A1
• Filed: 11/18/2009
• Published: 09/23/2010
• Est. Priority Date: 03/23/2009
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Xia, Pengfei, Rong, Zhigang, Tang, Yang
• Granted Patent: US 8,675,627 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 7/0469 taking special antenna structures, e.g. cross polarized antennas into account
• 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 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03605 Block algorithms
• CPC Class Codes: H04L 2025/03808 Transmission of equaliser coefficients
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

Adaptive precoding codebooks are described. In one embodiment, the method of wireless communication includes reading at least a rank-2 baseline codebook having codewords representing precoding matrices. An adaptive codebook is generated by multiplying a first column of the codeword with a first transform matrix calculated from a channel correlation matrix, and multiplying a second column of the codeword with a second transform matrix calculated from the channel correlation matrix. The first and the second transform matrices are orthogonal.

Claims

1. A method of wireless communication comprising:

at a processor, reading a baseline codebook of at least a rank-2, the baseline codebook comprising codewords representing precoding matrices; and

generating an adaptive codebook by;

multiplying a first column of a codeword of the baseline codebook with a first transform matrix calculated from a channel correlation matrix, and

multiplying a second column of the codeword with a second transform matrix calculated from the channel correlation matrix, wherein the first and the second transform matrices are orthogonal.

2. The method of claim 1, wherein the baseline codebook is a rank-2 codebook, and wherein the first transform matrix comprises a summation using the odd eigenmodes of the channel correlation matrix, and wherein the second transform matrix comprises a summation using the even eigenmodes of the channel correlation matrix.

3. The method of claim 1, further comprising:

after generating an adaptive codebook, at a receiver, selecting a codeword index of the adaptive codebook to quantize channel state information; and

transmitting the selected codeword index to a transmitter.

4. The method of claim 3, further comprising at the transmitter, selecting beamformers for transmitting data to the receiver based on the selected codeword index.

5. The method of claim 4, wherein the selected beamformers are exactly the same as the selected codeword index.

6. The method of claim 4, wherein the selected beamformers are different from the selected codeword index.

7. The method of claim 1, wherein the adaptive codebook is generated at both a receiver and a transmitter, and wherein the transmitter and the receiver exchange information to synchronize the use of the adaptive codebook.

8. The method of claim 7, further comprising:

calculating a channel correlation matrix before generating an adaptive codebook;

after exchanging information to synchronize, receiving a codeword index from a receiver;

retrieving a codeword from the adaptive codebook;

generating a precoding matrix from the codeword; and

precoding data to be transmitted using the precoding matrix.

9. The method of claim 1, wherein the adaptive codebook is generated periodically at specified time intervals.

10. The method of claim 1, wherein the adaptive codebook is generated when a predefined criterion is met.

11. The method of claim 10, wherein the criterion comprises a metric requiring a predefined threshold.

12. The method of claim 1, wherein generating an adaptive codebook further comprises multiplying a third column of the codeword with a third transform matrix calculated from the channel correlation matrix, wherein the third transform matrix is orthogonal with the first and the second transform matrices.

13. The method of claim 12, wherein the baseline codebook is a rank-3 codebook, and wherein the first transform matrix comprises a summation using 3k-2 eigenmodes of the channel correlation matrix, wherein the second transform matrix comprises a summation using 3k-1 eigenmodes of the channel correlation matrix, wherein the third transform matrix comprises a summation using 3k eigenmodes of the channel correlation matrix, and wherein k is a natural number less than the total number of transmitting antennas in a transmitter.

14. A method of wireless communication comprising:

at a mobile user device, generating an adaptive codebook by transforming a predefined baseline codebook of at least a rank-2, the baseline codebook comprising codewords representing precoding matrices, wherein the transforming comprises;

multiplying a first column of a codeword of the baseline codebook with a first transform matrix calculated from a channel correlation matrix, and

multiplying a second column of the codeword with a second transform matrix calculated from the channel correlation matrix, wherein the first and the second transform matrices are orthogonal.

15. The method of claim 14, further comprising, using the adaptive codebook, transmitting to a transmitter, a quantized form of a channel between the mobile user device and the transmitter.

16. The method of claim 14, wherein generating an adaptive codebook further comprises multiplying a third column of the codeword with a third transform matrix calculated from the channel correlation matrix, wherein the third transform matrix is orthogonal with the first and the second transform matrices.

17. The method of claim 16, wherein the baseline codebook is a rank-3 codebook, and wherein the first transform matrix comprises a summation using 3k-2 eigenmodes of the channel correlation matrix, wherein the second transform matrix comprises a summation using 3k-1 eigenmodes of the channel correlation matrix, and wherein the third transform matrix comprises a summation using 3k eigenmodes of the channel correlation matrix, wherein k is a natural number less than total number of transmitting antennas in a transmitter.

18. A method of wireless communication comprising:

at a base station, generating an adaptive codebook by transforming a predefined baseline codebook of at least a rank-2, the predefined baseline codebook comprising codewords representing precoding matrices, wherein the transforming comprises;

multiplying a first column of a codeword of the predefined baseline codebook with a first transform matrix calculated from a channel correlation matrix, and

multiplying a second column of the codeword with a second transform matrix calculated from the channel correlation matrix, wherein the first and the second transform matrices are orthogonal.

19. The method of claim 18, further comprising:

at the base station, receiving a codeword index from a mobile user device;

retrieving a codeword by looking up the index in the adaptive codebook;

generating a precoding matrix from the codeword; and

precoding data to be transmitted using the precoding matrix.

20. The method of claim 18, wherein generating an adaptive codebook further comprises multiplying a third column of the codeword with a third transform matrix calculated from the channel correlation matrix, wherein the third transform matrix is orthogonal with the first and the second transform matrices.

21. The method of claim 18, wherein the baseline codebook is a rank-3 codebook, and wherein the first transform matrix comprises a summation using 3k-2 eigenmodes of the channel correlation matrix, wherein the second transform matrix comprises a summation using 3k-1 eigenmodes of the channel correlation matrix, and wherein the third transform matrix comprises a summation using 3k eigenmodes of the channel correlation matrix, wherein k is a natural number less than the total number of transmitting antennas in the transmitter.

22. The method of claim 18, wherein the adaptive codebook is generated periodically at specified time intervals.