CLOSED-LOOP TRANSMISSION FEEDBACK IN WIRELESS COMMUNICATION SYSTEMS

• US 20090122884A1
• Filed: 11/09/2007
• Published: 05/14/2009
• Est. Priority Date: 11/09/2007
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: SAYANA, KRISHNA KAMAL, WANG, FAN, KRAUSS, THOMAS P., VOOK, FREDERICK W., ZHUANG, XIANGYANG
• Granted Patent: US 8,130,847 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals

Abstract

A method in an OFDM wireless user terminal that communicates with a base unit is disclosed. The method comprises computing a transmit spatial covariance matrix, transforming the spatial covariance matrix, and transmitting the transformed spatial covariance matrix to a base unit.

Claims

1. A method in an OFDM wireless subscriber terminal that communicates with a base unit, the method comprising:

computing a transmit spatial covariance matrix;

transforming the spatial covariance matrix;

transmitting the transformed spatial covariance matrix to a base unit.

2. The method of claim 1,

the spatial covariance matrix having multiple coefficients,

transforming includes mapping the coefficients of the spatial covariance matrix onto a feedback waveform,

transmitting the transformed spatial covariance matrix by transmitting the feedback waveform to the base unit.

3. The method of claim 2,

the feedback waveform includes multiple channels,

mapping the coefficients includes generating analog coefficients from the multiple coefficients and modulating the multiple channels with the analog coefficients.

4. The method of claim 1,

computing an Eigenvector of the spatial covariance matrix,

transforming includes scaling the Eigenvector by an associated factor,

transmitting the transformed spatial covariance matrix by transmitting the scaled Eigenvector to the base unit.

5. The method of claim 4, scaling includes multiplying

the eigenvector by an associated factor based on a corresponding eigenvalue.

6. The method of claim 4, scaling includes multiplying the eigenvector by an associated factor based on a corresponding eigenvalue a signal to noise ratio.

7. The method of claim 4, scaling includes multiplying the eigenvector by a factor chosen by the terminal.

8. A method in a wireless subscriber terminal that communicates with a base unit, the method comprising:

computing multiple transmit spatial covariance matrices, each of the multiple spatial covariance matrices corresponds to a different part of an operational bandwidth of the terminal;

transmitting information corresponding to each of the multiple spatial covariance matrices to a base unit.

9. The method of claim 8, computing multiple transmit spatial covariance matrices includes

computing a first transmit spatial covariance matrix corresponding to a first portion of the operational bandwidth of the terminal, and

computing a second transmit spatial covariance matrix corresponding to a second portion of the entire operational bandwidth of the terminal,

the first and second portions of the operational bandwidth are partially overlapping.

10. The method of claim 8, computing multiple transmit spatial covariance matrices includes

computing a first transmit spatial covariance matrix corresponding to a first portion of the operational bandwidth of the terminal, and

computing a second transmit spatial covariance matrix corresponding to a second portion of the entire operational bandwidth of the terminal,

the first and second portions of the operational bandwidth are non-overlapping.

11. The method of claim 8, receiving a message indicating the different parts of the operational bandwidth for which spatial covariance matrices should be computed.

12. The method of claim 8,

transforming each spatial covariance matrix,

transmitting each transformed spatial covariance matrix to a base unit.

13. The method of claim 12,

each spatial covariance matrix having multiple coefficients,

transforming includes mapping coefficients of each of the spatial covariance matrices onto a feedback waveform,

transmitting the transformed spatial covariance matrix includes transmitting the feedback waveform.

14. The method of claim 13,

the feedback waveform includes multiple channels,

mapping the coefficients includes generating analog coefficients from the multiple coefficients of each of the spatial covariance matrices, and modulating the multiple channels with the analog coefficients.

15. The method of claim 12,

computing an Eigenvector of each of the spatial covariance matrices,

transforming includes scaling each Eigenvector by an associated factor,

transmitting the transformed spatial covariance matrices by transmitting the scaled Eigenvectors.

16. The method of claim 8, indicating a preferred part of the operational bandwidth to the access point.

17. A method in a base unit, the method comprising:

receiving information for multiple spatial covariance matrices from a wireless communication terminal,

each of the spatial covariance matrices corresponding to a different parts of an operational bandwidth of the terminal,

determining a transmission waveform based on the information for the multiple spatial covariance matrices.

18. The method of claim 17, determining the transmission waveform includes performing band selection based on the information for the multiple spatial covariance matrices.

19. The method of claim 17, selecting includes performing band selection based on a relative channel quality for each of the different parts of the operational bandwidth based on the information for the multiple spatial covariance matrices.

20. The method of claim 17, transmitting a message to the wireless communication terminal indicating the different parts of the operational bandwidth for which spatial covariance matrices should be computed.