Reduced complexity beam-steered MIMO OFDM system

• US 8,824,583 B2
• Filed: 03/11/2013
• Issued: 09/02/2014
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Howard, Steven J., Ketchum, John W., Wallace, Mark S., Walton, Jay Rodney
• Primary Examiner(s): Kim, Kevin
• Application Number:
  US13/793,520
• Publication Number:
  US 20130188677A1
• Time in Patent Office: 540 Days
• Field of Search: 375/260, 375/295, 375/296, 455/69, 455/702, 455/703
• US Class Current: 375/260
• CPC Class Codes: H04B 7/0421 utilizing implicit feedback, e.g. steered pilot signals
• 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: H04B 7/066 Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
• 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 25/0248 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 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

Techniques for transmitting data using channel information for a subset of all subcarriers used for data transmission are described. A transmitter station receives channel information for at least one subcarrier that is a subset of multiple subcarriers used for data transmission. The channel information may include at least one transmit steering matrix, at least one set of eigenvectors, at least one channel response matrix, at least one channel covariance matrix, an unsteered pilot, or a steered pilot for the at least one subcarrier. The transmitter station obtains at least one transmit steering matrix for the at least one subcarrier from the channel information and determines a transmit steering matrix for each of the multiple subcarriers. The transmitter station performs transmit steering or beam-steering for each of the multiple subcarriers with the transmit steering matrix for that subcarrier.

Claims

1. An apparatus comprising:

at least one processor configured to send channel information for at least one subcarrier that is a subset of multiple subcarriers used to send data, and to receive a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier,

wherein the at least one processor is configured to obtain at least one channel response matrix for the at least one subcarrier, to decompose the at least one channel response matrix to obtain at least one transmit steering matrix, and to send a steered pilot on the at least one subcarrier using the at least one transmit steering matrix; 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 send the at least one transmit steering matrix as the channel information.

3. The apparatus of claim 1, wherein the at least one processor is configured to send the at least one code word as the channel information.

4. The apparatus of claim 1, wherein the at least one processor is configured to send the at least one channel response matrix as the channel information.

5. An apparatus comprising:

at least one processor configured to send channel information for at least one subcarrier that is a subset of multiple subcarriers used to send data, and to receive a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier,

wherein the at least one processor is configured to obtain at least one channel response matrix for the at least one subcarrier, to compute at least one channel covariance matrix for the at least one channel response matrix, and to send the at least one channel covariance matrix as the channel information; and

a memory coupled to the at least one processor.

6. An apparatus comprising:

at least one processor configured to send channel information for at least one subcarrier that is a subset of multiple subcarriers used to send data, and to receive a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier,

wherein the at least one processor is configured to obtain multiple channel response matrices for the multiple subcarriers, to derive multiple spatial filter matrices for the multiple subcarriers based on the multiple channel response matrices, and to perform detection for the multiple subcarriers with the multiple spatial filter matrices; and

a memory coupled to the at least one processor.

7. The apparatus of claim 6, wherein the at least one processor is configured to decompose at least one channel response matrix for the at least one subcarrier to obtain at least one transmit steering matrix, to determine the transmit steering matrices for the multiple subcarriers based on the at least one transmit steering matrix, and to derive a spatial filter matrix for each of the multiple subcarriers based on a channel response matrix and a transmit steering matrix for the subcarrier.

8. The apparatus of claim 7, wherein the at least one processor is configured to set the transmit steering matrix for each of the multiple subcarriers equal to a transmit steering matrix obtained for a closest one of the at least one subcarrier.

9. The apparatus of claim 6, wherein the at least one processor is configured to derive the multiple spatial filter matrices for the multiple subcarriers in accordance with minimum mean square error (MMSE) detection technique.

10. An apparatus comprising:

at least one processor configured to send channel information for at least one subcarrier that is a subset of multiple subcarriers used to send data, and to receive a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier,

wherein the at least one processor is configured to determine frequency selectivity of a wireless channel and to determine the number of subcarriers for sending channel information based on the frequency selectivity of the wireless channel; and

a memory coupled to the at least one processor.

11. An apparatus comprising:

at least one processor configured to send channel information for at least one subcarrier that is a subset of multiple subcarriers used to send data, and to receive a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier,

wherein the at least one processor is configured to determine delay spread of a wireless channel and to determine the number of subcarriers for sending channel information based on the delay spread of the wireless channel; and

a memory coupled to the at least one processor.

12. A method comprising:

obtaining at least one channel response matrix for at least one subcarrier that is a subset of multiple subcarriers used to send data;

decomposing the at least one channel response matrix to obtain at least one transmit steering matrix;

sending channel information for the at least one subcarrier, wherein the sending the channel information comprises sending a steered pilot on the at least one subcarrier using the at least one transmit steering matrix; and

receiving a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier.

13. The method of claim 12, wherein the channel information further comprises the at least one transmit steering matrix.

14. A method comprising:

sending channel information for at least one subcarrier that is a subset of multiple subcarriers used to send data;

receiving a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier;

obtaining multiple channel response matrices for the multiple subcarriers;

decomposing at least one channel response matrix for the at least one subcarrier to obtain at least one transmit steering matrix;

deriving multiple spatial filter matrices for the multiple subcarriers based on the multiple channel response matrices and the at least one transmit steering matrix; and

performing detection for the multiple subcarriers with the multiple spatial filter matrices.

18. The method of claim 14, further comprising:

decomposing at least one channel response matrix for the at least one subcarrier to obtain at least one transmit steering matrix;

determining the transmit steering matrices for the multiple subcarriers based on the at least one transmit steering matrix; and

deriving a spatial filter matrix for each of the multiple subcarriers based on a channel response matrix and a transmit steering matrix for the subcarrier.

19. The method of claim 18, further comprising setting the transmit steering matrix for each of the multiple subcarriers equal to a transmit steering matrix obtained for a closest one of the at least one subcarrier.

20. The method of claim 14, further comprising deriving the multiple spatial filter matrices for the multiple subcarriers in accordance with minimum mean square error (MMSE) detection technique.

15. An apparatus comprising:

means for obtaining at least one channel response matrix for at least one subcarrier that is a subset of multiple subcarriers used to send data;

means for decomposing the at least one channel response matrix to obtain at least one transmit steering matrix;

means for sending channel information for the at least one subcarrier, wherein the means for sending the channel information comprises means for sending a steered pilot on the at least one subcarrier using the at least one transmit steering matrix; and

means for receiving a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier.

16. The apparatus of claim 15, further comprising:

means for obtaining at least one channel response matrix for the at least one subcarrier; and

means for decomposing the at least one channel response matrix to obtain at least one transmit steering matrix, wherein the channel information comprises the at least one transmit steering matrix.

17. A non-transitory computer-readable medium including instructions stored thereon, comprising:

a first instruction set for obtaining at least one channel response matrix for at least one subcarrier that is a subset of multiple subcarriers used to send data;

a second instruction for decomposing the at least one channel response matrix to obtain at least one transmit steering matrix; and

a third instruction for sending channel information for the at least one subcarrier, wherein the channel information includes sending a steered pilot on the at least one subcarrier using the at least one transmit steering matrix; and

a fourth instruction set for directing reception of a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier.

21. A method comprising:

determining frequency selectivity of a wireless channel;

determining a number of subcarriers that is a subset of multiple subcarriers used to send data for sending channel information based on the frequency selectivity of the wireless channel;

sending the channel information for at least one subcarrier of the subset; and

receiving a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier.

22. A method comprising:

determining delay spread of a wireless channel;

determining a number of subcarriers that is a subset of multiple subcarriers used to send data for sending channel information based on the delay spread of the wireless channel;

sending the channel information for at least one subcarrier of the subset; and

receiving a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier.

23. A method comprising:

obtaining at least one channel response matrix for at least one subcarrier that is a subset of multiple subcarriers used to send data;

computing at least one channel covariance matrix for the at least one channel response matrix;

sending channel information for the at least one subcarrier, wherein the channel information comprises the at least one channel covariance matrix as the channel information; and

receiving a data transmission sent on the multiple subcarriers from multiple transmit antennas to multiple receive antennas using transmit steering matrices derived for the multiple subcarriers based on the channel information for the at least one subcarrier.