Method of aiding uplink beamforming transmission

• US 20090190488A1
• Filed: 02/29/2008
• Published: 07/30/2009
• Est. Priority Date: 01/28/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Beceem Communications, Inc. (Broadcom, Inc.)
• Inventors: Hochwald, Bertrand, Artes, Harold
• Granted Patent: US 8,259,672 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

A method and apparatus of aiding uplink beamforming transmission is disclosed. One method includes a base station downlink transmitting beamformed signals to at least a first terminal, the beam formed signals directed and conveying data to at least the first terminal. The method further includes a second terminal eavesdropping the transmitted beamformed signals, and measuring a signal quality. The second terminal estimates uplink channel information based on the measured signal quality, for aiding uplink transmission. Based at least in part on the estimated transmission channel, the second terminal transmits beamformed uplink signals to the base station.

Claims

1. A method of aiding uplink transmission, comprising:

a base station downlink transmitting beamformed signals to at least a first terminal, the beam formed signals directed and conveying data to at least the first terminal;

a second terminal eavesdropping the transmitted beamformed signals, and measuring a signal quality;

the second terminal estimating uplink channel information based on the measured signal quality, for aiding uplink transmission.

2. The method of claim 1, further comprising:

the second terminal uplink transmitting beamformed uplink signals to the base station, the beamformed uplink signals formed at least in part based on the uplink channel information.

3. The method of claim 1, further comprising establishing a relationship between an uplink channel associated with the uplink channel information, and a corresponding downlink channel.

4. The method of claim 2, wherein downlink transmission of the base station and uplink transmission of the second terminal occur at different times.

5. The method of claim 1, wherein the beamformed signals comprise pilots.

6. The method of claim 1, further comprising the second terminal creating or updating channel information between the second terminal and the base station based on the uplink channel information.

7. The method of claim 1, further comprising the second terminal updating at least one beam that is formed to aid transmission between the second terminal and the base station based on the uplink channel information.

8. The method of claim 1, further comprising the base station transmitting beamformed signals to a plurality of terminals, and the second terminal receiving the transmitted beamformed signals, and measuring corresponding signal qualities.

9. The method of claim 1, further comprising the second terminal identifying beam formed signals that have a quality of at least one of above a threshold, or below a threshold.

10. The method of claim 1, further comprising the second terminal identifying channels for transmitting uplink sounding based on the measured signal quality, of the beamformed signals.

11. The method of claim 1, further comprising:

the second terminal receiving the transmitted beamformed signals over multiple receive antennas, and measuring a joint signal quality indicator.

12. The method of claim 11, further comprising the second terminal determining whether the second terminal is to transmit in a beamforming mode or a spatial multiplexing mode based on the joint signal quality indicator.

13. The method of claim 12, wherein the joint signal quality indicator includes a signal quality difference between the multiple receive antennas, and if the signal quality difference between the multiple antennas varies by greater than a threshold, then the second terminal selects spatial multiplexing for transmission to the base station.

14. The method of claim 12, wherein the joint signal quality indicator includes a signal quality difference between the multiple receive antennas, and if the measured signal quality between the multiple receive antennas varies by less than a threshold, then the second terminal selects beamforming for transmission to the base station.

15. The method of claim 12, further comprising the base station determining whether to transmit in a beamforming mode or a spatial multiplexing mode based on a joint signal quality indicator, wherein the joint signal quality indicator comprises measured signal qualities of multiple beams at the multiple receive antennas.

16. The method of claim 1, further comprising the base station cyclic-delaying the transmitted beamformed signals.

17. The method of claim 16, further comprising the second terminal selecting frequency sub-carriers of the cyclic-delayed transmitted beamformed signals for reception and signal quality measurement, based on a frequency dependency of the frequency sub-carriers of the cyclic-delayed transmitted beamformed signals.

18. The method of claim 1, wherein the base station forms the beamformed signals to be spatially orthogonal, comprising:

estimating a channel matrix;

computing a singular value decomposition of the estimated channel matrix;

computing an orthogonal set from the singular value decomposition;

the base station generating the spatially orthogonal beams by selecting columns of the orthogonal set.

19. A method of aiding uplink transmission, comprising:

a base station downlink transmitting beamformed signals to a plurality of terminals, the beam formed signals directed and conveying data to each of the plurality of terminals, each beamformed signal directed to each of the plurality of terminals being spatially orthogonal to the other beamformed signals directed to other terminals;

a second terminal eavesdropping the transmitted beamformed signals, and measuring a signal quality;

the second terminal estimating uplink channel information based on the measured signal quality, for aiding uplink transmission;

the second terminal uplink transmitting beamformed uplink signals to the base station, the beamformed uplink signals formed at least in part based on the estimated uplink channel information.

20. The method of claim 19, wherein the base station forms the beamformed signals to be spatially orthogonal, comprising:

estimating a channel matrix;

computing a singular value decomposition of the estimated channel matrix;

computing an orthogonal set from the singular value decomposition;

the base station generating the spatially orthogonal beams by selecting columns of the orthogonal set.

21. The method of claim 19, further comprising the base station cyclic-delaying the transmitted beamformed signals.

22. The method of claim 21, further comprising the second terminal selecting frequency sub-carriers of the cyclic-delayed transmitted beamformed signals for reception and signal quality measurement, based on a frequency dependency of the frequency sub-carriers of the cyclic-delayed transmitted beamformed signals.

23. The method of claim 21, further comprising augmenting selection of sounding symbols for uplink sounding based on the uplink channel information.

24. The method of claim 23, wherein sounding symbols are selected only on frequency carriers in which beamformed signals can be received from the base station having a predetermined signal quality.

25. A method of aiding uplink transmission, comprising:

a terminal receiving downlink transmitted beamformed signals, and measuring a signal quality, wherein the downlink transmitting beamformed signals are transmitted from a base station to a plurality of terminals, the beam formed signals directed and conveying data to each of the plurality of terminals, each beamformed signal directed to each of the plurality of terminals being spatially orthogonal to the other beamformed signals directed to other terminals;

the terminal estimating uplink channel information based on the measured signal quality;

the terminal uplink transmitting beamformed uplink signals to the base station, the beamformed uplink signals formed at least in part based on the estimated uplink channel information.