Power amplifier adjustment for transmit beamforming in multi-antenna wireless systems

• US 8,165,543 B2
• Filed: 04/24/2008
• Issued: 04/24/2012
• Est. Priority Date: 04/25/2007
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Zhang, Hongyuan, Rohit, Nabar U.
• Primary Examiner(s): HANNON, CHRISTIAN A
• Application Number:
  US12/109,257
• Publication Number:
  US 20080266176A1
• Time in Patent Office: 1,461 Days
• Field of Search: 455/115.1, 455/115.3, 455/127.2, 455/127.3, 455/129
• US Class Current: 455/127.3
• CPC Class Codes: H01Q 3/40 with phasing matrix
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

One or more beamsteering matrices are applied to a plurality of signals to be transmitted via multiple antennas. The plurality of signals are provided to a plurality of power amplifiers coupled to the multiple antennas after applying the one or more beamsteering matrices to the plurality of signals. Signal energies are determined for the plurality of signals provided to the plurality of power amplifiers, and output power levels of the plurality of power amplifiers are adjusted based on the determined signal energies.

Claims

1. A method, comprising:

applying one or more beamsteering matrices to a plurality of signals to be transmitted via multiple antennas;

after applying the one or more beamsteering matrices to the plurality of signals, providing the plurality of signals to a plurality of power amplifiers coupled to the multiple antennas;

determining signal energies for the plurality of signals provided to the plurality of power amplifiers;

comparing one of the determined signal energies to each of one or more other determined signal energies;

determining a maximum signal energy corresponding to one of the plurality of signals;

determining one or more ratios, comprising, for each of the one or more other signals in the plurality of signals, determining a respective ratio of the signal energy of the other signal to the maximum signal energy; and

controlling the plurality of power amplifiers via power amplifier control inputs to adjust output power levels of the plurality of power amplifiers, wherein adjusting output power levels comprises

i) setting an output power level of a power amplifier corresponding to the maximum signal energy to a defined output power level, and

ii) setting a corresponding output power level for each of one or more additional power amplifiers to a corresponding power level based on a corresponding determined ratio.

2. The method of claim 1, wherein determining signal energies for the plurality of signals comprises analyzing the plurality of signals.

3. The method of claim 2, wherein determining signal energies for the plurality of signals comprises computing respective sums of squared amplitudes for the plurality of signals provided to the plurality of power amplifiers.

4. The method of claim 1, wherein determining signal energies for the plurality of signals comprises analyzing the one or more beamsteering matrices.

5. The method of claim 4, wherein determining signal energies for the plurality of signals comprises summing squared magnitudes of matrix coefficients in rows of the one or more beamsteering matrices.

6. The method of claim 4, wherein applying the one or more beamsteering matrices to the plurality of signals comprises applying a plurality of beamsteering matrices to the plurality of signals;

wherein determining signal energies for the plurality of signals comprises summing squared magnitudes of matrix coefficients in rows of a subset of the plurality of beamsteering matrices.

7. The method of claim 1, wherein, for each of the one or more additional power amplifiers, the corresponding power level is below the defined output power level.

8. The method of claim 1, wherein the defined output power level is a maximum output power level.

9. The method of claim 1, wherein comparing the signal energies for the plurality of signals provided to the plurality of power amplifiers comprises comparing each of the signal energies to a reference signal energy.

10. The method of claim 1, wherein adjusting the output power levels of the plurality of power amplifiers comprising adjusting the output power levels of the plurality of power amplifiers so that the relative output power levels correspond to the relative signal energies.

11. The method of claim 1, wherein adjusting the output power levels of the plurality of power amplifiers comprising adjusting the output power levels of the plurality of power amplifiers so that the output power levels are equal.

12. A power amplifier control apparatus, comprising a controller configured to:

determine signal energies for a plurality of signals provided to a plurality of power amplifiers coupled to a plurality of transmit antennas, wherein one or more beamsteering matrices are applied to the plurality of signals;

compare one of the determined signal energies to each or one or more other determined signal energies;

determine a maximum signal energy corresponding to one of the plurality of signals;

determine one or more ratios, comprising, for each of the one or more other signals in the plurality of signals, determining a respective ratio of the signal energy of the other signal to the maximum signal energy; and

generate control signals to be supplied to control inputs of the plurality of power amplifiers to adjust output power levels of the plurality of power amplifiers, wherein adjusting output power levels comprises

i) setting an output power level of a power amplifier corresponding to the maximum signal energy to a defined output power level and

ii) setting a corresponding output power level for each of one or more additional power amplifiers to a corresponding power level based on a corresponding determined ratio.

13. The apparatus of claim 12, wherein the controller receives the plurality of signals and is configured to determine the signal energies for the plurality of signals based on an analysis of the plurality of signals.

14. The apparatus of claim 13, wherein the controller is configured to compute respective sums of squared amplitudes for the plurality of signals.

15. The apparatus of claim 12, wherein the controller receives one or more beamsteering matrices and is configured to determine the signal energies for the plurality of signals based on an analysis of the one or more beamsteering matrices.

16. The apparatus of claim 15, wherein the controller is configured to sum squared magnitudes of matrix coefficients in rows of the one or more beamsteering matrices.

17. The apparatus of claim 15, wherein the one or more beamsteering matrices comprises a plurality of beamsteering matrices;

wherein the controller is configured to sum squared magnitudes of matrix coefficients in rows of a subset of the plurality of beamsteering matrices.

18. The apparatus of claim 12, wherein the controller is configured to generate the control signals to set the corresponding power level for each of the one or more additional power amplifiers to a corresponding power level that is below the defined output power level.

19. The apparatus of claim 12, wherein the controller is configured to compare each of the signal energies to a reference signal energy.

20. The apparatus of claim 12, wherein the controller is configured to adjust the output power levels of the plurality of power amplifiers so that the relative output power levels correspond to the relative signal energies.

21. The apparatus of claim 12, wherein the controller is configured to adjust the output power levels of the plurality of power amplifiers so that the output power levels are equal.

22. A wireless transmitter for transmitting an information signal, the wireless transmitter comprising:

a signal modulator adapted to modulate the information signal to produce a modulated signal;

a plurality of transmission antennas;

a beamforming network coupled between the signal modulator and the plurality of transmission antennas;

a first controller coupled to the beamforming network to control the beamforming network using one or more beamsteering matrices so as to produce a transmit gain pattern having one or more high gain lobes when the modulated signal is transmitted via the plurality of transmission antennas;

a plurality of power amplifiers coupled to the beamforming network and the plurality of transmission antennas; and

a second controller coupled to the plurality of amplifiers, the second controller configured to;

determine signal energies for a plurality of signals provided to the plurality of power amplifiers,

compare one of the determined signal energies to each or one or more other determined signal energies;

determine a maximum signal energy corresponding to one of the plurality of signals;

determine one or more ratios, comprising, for each of the one or more other signals in the plurality of signals, determining a respective ratio of the signal energy of the other signal to the maximum signal energy; and

generate control signals to be supplied to control inputs of the plurality of power amplifiers to adjust output power levels of the plurality of power amplifiers, wherein adjusting output power levels comprises

i) setting an output power level of a power amplifier corresponding to the maximum signal energy to a defined output power level and

ii) setting a corresponding output power level for each of one or more additional power amplifiers to a corresponding power level based on a corresponding determined ratio.

23. The wireless transmitter of claim 22, wherein the second controller receives the plurality of signals;

wherein the second controller is configured to determine the signal energies for the plurality of signals based on an analysis of the plurality of signals.

24. The wireless transmitter of claim 22, wherein the second controller receives the one or more beamsteering matrices;

wherein the second controller is configured to determine the signal energies for the plurality of signals based on an analysis of the one or more beamsteering matrices.

25. The wireless transmitter of claim 24, wherein the second controller is coupled to a steering matrix memory.

26. The wireless transmitter of claim 22, further comprising a steering matrix calculation unit.

27. The wireless transmitter of claim 22, wherein the second controller is configured to adjust the output power levels of the plurality of power amplifiers so that the relative output power levels correspond to the relative signal energies.

28. The wireless transmitter of claim 22, wherein the second controller is configured to adjust the output power levels of the plurality of power amplifiers so that the output power levels are equal.

29. A method of wirelessly transmitting an information signal via multiple antennas, the method comprising:

modulating the information signal to produce a modulated signal;

applying one or more beamsteering matrices to the modulated signal to produce a plurality of output signals;

providing the plurality of output signals to a plurality of power amplifiers, wherein the plurality of power amplifiers are coupled to the multiple antennas;

determining signal energies for the plurality of output signals;

comparing one of the determined signal energies to each of one or more other determined signal energies;

determining a maximum signal energy corresponding to one of the plurality of signals;

determining one or more ratios, comprising, for each of the one or more other signals in the plurality of signals, determining a respective ratio of the signal energy of the other signal to the maximum signal energy; and

controlling the plurality of power amplifiers via power amplifier control inputs to adjust output power levels of the plurality of power amplifiers, wherein adjusting output power levels comprises

i) setting an output power level of a power amplifier corresponding to the maximum signal energy to a defined output power level, and

ii) setting a corresponding output power level for each of one or more additional power amplifiers to a corresponding power level based on a corresponding determined ratio.

30. The method of claim 29, wherein determining signal energies for the plurality of output signals comprises analyzing the plurality of output signals.

31. The method of claim 29, wherein determining signal energies for the plurality of output signals comprises analyzing the one or more beamsteering matrices.

32. The method of claim 29, wherein adjusting the output power levels of the plurality of power amplifiers comprising adjusting the output power levels of the plurality of power amplifiers so that the relative output power levels correspond to the relative signal energies.

33. The method of claim 29, wherein adjusting the output power levels of the plurality of power amplifiers comprising adjusting the output power levels of the plurality of power amplifiers so that the output power levels are equal.