Beamforming scheme for phased-array antennas

• US 8,446,317 B1
• Filed: 05/17/2012
• Issued: 05/21/2013
• Est. Priority Date: 09/24/2008
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Wu, Songping, Shen, Manyuan, Zhou, Quan, Zhang, Hongyuan, Lou, Hui-Ling
• Primary Examiner(s): GALT, CASSI J
• Application Number:
  US13/474,691
• Time in Patent Office: 369 Days
• Field of Search: 342/367, 342/368, 342/377, 342132-141, 455132-141
• US Class Current: 342/368
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/40 with phasing matrix
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/088 using beam selection

Abstract

In a method for beamforming in communication a system, a plurality of different antenna weight vectors are generated. Each of the plurality of antenna weight vectors is a respective base vector of a unitary matrix. At least one training signal is transmitted a plurality of times via a plurality of antennas. A respective antenna weight vector from the plurality of different antenna weight vectors is applied each time the at least one training signal is transmitted. Feedback signals are received, where the feedback signals correspond to the at least one training signal transmitted the plurality of times and received at a receiver. A transmitter antenna weight vector is generated based on a mathematical combination of at least (i) the at least one training signal and (ii) the feedback signals.

Claims

1. A method for beamforming in a communication system, the method comprising:

generating a plurality of different antenna weight vectors, wherein each of the plurality of antenna weight vectors is a respective base vector of a unitary matrix;

transmitting, a plurality of times, at least one training signal via a plurality of antennas, wherein a respective antenna weight vector from the plurality of different antenna weight vectors is applied each time the at least one training signal is transmitted;

receiving feedback signals corresponding to the at least one training signal transmitted the plurality of times and received at a receiver; and

generating a transmitter antenna weight vector based on a mathematical combination of at least (i) the at least one training signal and (ii) the feedback signals.

2. The method of claim 1, wherein a number of antenna weight vectors in the plurality of different antenna weight vectors is equal to a number of antennas in the plurality of antennas, so that the plurality of different antenna weight vectors completely defines the unitary matrix.

3. The method of claim 1, wherein a number of antenna weight vectors in the plurality of different antenna weight vectors is less than a number of antennas in the plurality of antennas.

4. The method of claim 1, further comprising selecting the plurality of different antenna weight vectors from the unitary matrix based on past history of generating antenna weight vectors for transmit beamforming.

5. The method of claim 1, wherein:

the plurality of antennas is associated with a resolution; and

the method further comprises quantizing the transmitter antenna weight vector to the resolution of the plurality of antennas.

6. The method of claim 1, wherein generating the transmitter antenna weight vector comprises generating the transmitter antenna weight vector based on a mathematical combination of (i) the at least one training signal, (ii) the feedback signals, and (iii) the plurality of different antenna weight vectors.

7. The method of claim 1, wherein each of the plurality of different antenna weight vectors is a phase-only vector.

8. The method of claim 1, wherein each of the plurality of different antenna weight vectors is an amplitude-only vector.

9. The method of claim 1, further comprising:

generating a respective quality indicator for each antenna weight vector in the plurality of antenna weight vectors based on the feedback signals;

comparing each quality indicator to a threshold quality value; and

determining when to stop transmitting the at least one training signal based on the comparisons of each quality indicator to the threshold quality value.

10. The method of claim 1, further comprising setting an amplitude of the receiver antenna weight vector to unity.

11. The method of claim 1, further comprising:

repeating transmitting the at least one training signal, receiving feedback signals, and generating the transmitter antenna weight vector for each of a plurality of sub-carriers to define a plurality of sub-carrier-specific transmitter antenna weight vectors,

wherein generating the transmitter antenna weight vector is based on the plurality of sub-carrier-specific receiver antenna weight vectors.

12. The method of claim 1, further comprising:

repeating transmitting the at least one training signal, receiving feedback signals, and generating the transmitter antenna weight vector at each of a plurality of time-instances to define a plurality of time-specific transmitter antenna weight vectors,

wherein generating the transmitter antenna weight vector is based on the plurality of time-specific transmitter antenna weight vectors.

13. An apparatus comprising:

a base vector generator to provide a plurality of different antenna weight vectors, wherein each of the plurality of different antenna weight vectors is a respective base vector of a unitary matrix;

a beamforming network;

a beamforming controller configured to apply a respective antenna weight vector from the plurality of different antenna weight vectors each time at least one training signal is transmitted, wherein the at least one training signal is transmitted a plurality of times via a plurality of antennas; and

a vector selection unit configured to generate a transmitter antenna weight vector based on a mathematical combination of at least (i) the at least one training signal and (ii) feedback signals corresponding to the at least one training signal transmitted the plurality of times and received at a receiver.

14. The apparatus of claim 13, wherein the base vector generator is configured to select the plurality of different antenna weight vectors from the unitary matrix based on past history of generating antenna weight vectors for transmit beamforming.

15. The apparatus of claim 13, wherein:

the plurality of antennas is associated with a certain resolution; and

the vector selection unit is configured to quantize the transmitter antenna weight vector to the resolution of the plurality of antennas.

16. The apparatus of claim 13, wherein the vector selection unit is configured to generate the transmitter antenna weight vector based on a mathematical combination of (i) the at least one training signal, (ii) the feedback signals, and (iii) the plurality of different antenna weight vectors.

17. The apparatus of claim 13, wherein each of the plurality of different antenna weight vectors is a phase-only vector.

18. The apparatus of claim 13, wherein each of the plurality of different antenna weight vectors is an amplitude-only vector.

19. The apparatus of claim 13, wherein the vector selection unit is configured to set an amplitude of the receiver antenna weight vector to unity.

20. The apparatus of claim 13, wherein the vector selection unit is configured to generate the transmitter antenna weight vector based on a plurality of sub-carrier-specific receiver antenna weight vectors.

21. The apparatus of claim 13, wherein the vector selection unit is configured to generate the transmitter antenna weight vector based on a plurality of time-specific transmitter antenna weight vectors.