Channel reciprocity matrix determination in a wireless MIMO communication system

• US 7,894,852 B2
• Filed: 06/29/2007
• Issued: 02/22/2011
• Est. Priority Date: 07/13/2005
• Status: Active Grant

• Current Assignee: Bell Northern Research, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Hansen, Christopher J.
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US11/770,975
• Publication Number:
  US 20070249392A1
• Time in Patent Office: 1,334 Days
• Field of Search: 455/101, 455/422, 455/432.1, 455/434, 455/435.1, 455/435.2, 455/553.1, 455/561, 370/310.2, 370/319, 370/328, 370/334
• US Class Current: 455/552.1
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• 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 25/0242 using matrix methods
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

Operating a wireless MIMO system to determine forward and reverse channel reciprocity matrices relating a first wireless MIMO device and a second wireless MIMO device of the wireless MIMO system includes, during each of a plurality of time intervals, determining a forward composite channel estimates and a reverse composite channel estimates between the first wireless MIMO device and the second wireless MIMO device to yield a plurality of forward composite channel estimates and a plurality of reverse composite channel estimates. Operation continues with creating a mathematical relationship between the plurality of forward composite channel estimates and the plurality of reverse composite channel estimates and the forward and reverse channel reciprocity matrices. Operation concludes with finding a solution to the mathematical relationship between the plurality of forward composite channel estimates and the plurality of reverse composite channel estimates to yield the forward reciprocity matrix and the reverse channel reciprocity matrix.

Claims

1. A method for operating a MIMO client device to support wireless communication with a MIMO base station, the method for operating the MIMO client device comprising:

determining a plurality of first channel estimates based upon signals received from the MIMO base station, the plurality of first channel estimates representative of the MIMO base station as a transmitter and the MIMO client device as a receiver;

transmitting the plurality of first channel estimates to the MIMO base station;

receiving at least one channel reciprocity matrix from the MIMO base station, the at least one channel reciprocity matrix being non-diagonal and based upon at least the plurality of first channel estimates;

receiving from the MIMO base station a second channel estimate representative of the MIMO client device as a transmitter and the MIMO base station as a receiver;

transforming the second channel estimate using the at least one channel reciprocity matrix to produce a transformed second channel estimate, the transformed second channel estimate representative of the MIMO base station as a transmitter and the MIMO client device as a receiver; and

using the transformed second channel estimate to determine channel equalizer coefficients for use in equalizing signals received from the MIMO base station.

2. The method of claim 1, wherein the at least one channel reciprocity matrix is non-symmetrical.

3. The method of claim 1, wherein the MIMO base station and the MIMO client device are an N×

M MIMO system, where M is not equal to N.

4. The method of claim 1, wherein the MIMO base station and the MIMO client device are an N×

N MIMO system.

5. The method of claim 1, further comprising communicating with the MIMO base station according to a Wireless Local Area Network (WLAN) communication protocol.

6. A method for operating a MIMO base station to support wireless communications with a MIMO client device, the method comprising:

determining a plurality of first channel estimates based upon signals received from the MIMO client device, the plurality of first channel estimates representative of the MIMO client device as a transmitter and the MIMO base station as a receiver;

receiving a plurality of second channel estimates from the MIMO client device, the plurality of second channel estimates representative of the MIMO base station as a transmitter and the MIMO client device as a receiver;

determining at least one channel reciprocity matrix based upon the plurality of first channel estimates and the plurality of second channel estimates, the at least one channel reciprocity matrix being non-diagonal;

transmitting the at least one channel reciprocity matrix to the MIMO client device;

determining a third channel estimate based upon signals received from the MIMO client device;

using the third channel estimate to determine channel equalizer coefficients; and

using the channel equalizer coefficients to equalize signals received from the MIMO client device.

7. The method of claim 6, wherein the at least one channel reciprocity matrix is non-symmetrical.

8. The method of claim 6, wherein the MIMO base station and the MIMO client device are an N×

M MIMO system, where M is not equal to N.

9. The method of claim 6, wherein the MIMO base station and the MIMO client device are an N×

N MIMO system.

10. The method of claim 6, further comprising communicating with the MIMO base station according to a Wireless Local Area Network (WLAN) communication protocol.

11. A MIMO client device that supports wireless communication with a MIMO base station, the MIMO client device comprising:

a plurality of antennas;

a Radio Frequency (RF) front end coupled to the plurality of antennas; and

a baseband processing module coupled to the RF front end and operable to;

determine a plurality of first channel estimates based upon signals received from the MIMO base station via the RF front end, the plurality of first channel estimates representative of the MIMO base station as a transmitter and the MIMO client device as a receiver;

transmit the plurality of first channel estimates to the MIMO base station via the RF front end;

receive at least one channel reciprocity matrix from the MIMO base station via the RF front end, the at least one channel reciprocity matrix being non-diagonal and based upon at least the plurality of first channel estimates;

receive from the MIMO base station via the RF front end a second channel estimate representative of the MIMO client device as a transmitter and the MIMO base station as a receiver;

transform the second channel estimate using the at least one channel reciprocity matrix to produce a transformed second channel estimate, the transformed second channel estimate representative of the MIMO base station as a transmitter and the MIMO client device as a receiver; and

use the transformed second channel estimate to determine channel equalizer coefficients for use in equalizing signals received from the MIMO base station via the RF front end.

12. The MIMO client device of claim 11, wherein the at least one channel reciprocity matrix is non-symmetrical.

13. The MIMO client device of claim 11, wherein the MIMO client device and the MIMO base station are an N×

M MIMO system, where M is not equal to N.

14. The MIMO client device of claim 11, wherein the MIMO client device and the MIMO base station are an N×

N MIMO system.

15. The MIMO client device of claim 11, wherein the MIMO client device supports a Wireless Local Area Network (WLAN) communication protocol.

16. A MIMO device operable to support wireless communications with a second MIMO client device, the MIMO device comprising:

a plurality of antennas;

a Radio Frequency (RF) front end coupled to the plurality of antennas; and

a baseband processing module coupled to the RF front end and operable to;

determine a plurality of first channel estimates based upon signals received from the second MIMO client device via the RF interface, the plurality of first channel estimates representative of the second MIMO client device as a transmitter and the MIMO device as a receiver;

receive a plurality of second channel estimates from the second MIMO client device via the RF interface, the plurality of second channel estimates representative of the MIMO device as a transmitter and the second MIMO device as a receiver;

determine at least one channel reciprocity matrix based upon the plurality of first channel estimates and the plurality of second channel estimates, the at least one channel reciprocity matrix being non-diagonal; and

transmit the at least one channel reciprocity matrix to the second MIMO client device via the RF interface.

17. The MIMO device of claim 16, wherein the baseband processing module is further operable to:

determine a third channel estimate based upon signals received via the RF front end from the second client device;

use the third channel estimate to determine channel equalizer coefficients; and

use the channel equalizer coefficients to equalize signals received via the RF front end from the second client device.

18. The MIMO device of claim 16, wherein the at least one channel reciprocity matrix is non-symmetrical.

19. The MIMO device of claim 16, wherein a wireless MIMO system comprised of the MIMO device and the second MIMO device is an N×

M MIMO system, where M is not equal to N.

20. The MIMO device of claim 16, wherein a wireless MIMO system comprised of the MIMO device and the second MIMO device is an N×

N MIMO system.

21. The MIMO device of claim 16, wherein the MIMO client device supports a Wireless Local Area Network (WLAN) communication protocol.