System and method for distortion correction in MIMO and multiband transmitters

1. A method for multiple-input multiple-output impairment pre-compensation in a multiple-input and multiple-output transmitter having a multiple-input multiple-output radio frequency (RF) power amplifier, comprising:

receiving at the multiple-input and multiple-output transmitter a plurality of input signals forming a multiple-input signal;

generating a pre-distorted multiple-input signal from the received multiple-input signal;

generating a multiple-output signal by feeding the pre-distorted multiple-input signal into the multiple-input and multiple-output transmitter;

estimating impairments generated by nonlinear crosstalk in the multiple-input and multiple-output RF power amplifier, the nonlinear crosstalk being generated between respective channels of the multiple-input and multiple-output RF power amplifier while being driven by the plurality of input signals; and

adjusting the pre-distorted multiple-input signal to compensate for the estimated impairments.

2. The method of claim 1 , wherein generating the pre-distorted multiple-input signal comprises feeding the received multiple-input signal to a matrix of pre-processing cells.

3. The method of claim 2 , wherein each of the pre-processing cells includes nonlinear processing blocks compensating for multiple-input multiple-output nonlinear distortions and an effect of interferences between signal paths of the multiple-input signal and signal paths of the multiple-output signal.

4. The method of claim 3 , comprising, in the nonlinear processing blocks:

processing the multiple-input signal and the multiple-output signal to determine a desired multiple-output signal that pre-compensates for the nonlinear distortions; and

estimating a nonlinear function for each nonlinear processing block.

5. The method of claim 2 , wherein each of the pre-processing cells includes linear processing blocks compensating for multiple-input multiple-output linear distortions and an effect of interferences between signal paths of the multiple-input signal and signal paths of the multiple-output signal.

6. The method of claim 5 , comprising, in the linear processing blocks:

processing the multiple-input signal and the multiple-output signal to determine a desired multiple-output signal that pre-compensates for the linear distortions; and

estimating a linear function for each linear processing block.

7. The method of claim 2 , comprising, in each of the pre-processing cells of the matrix:

nonlinear processing blocks compensating for multiple-input multiple-output nonlinear distortions and an effect of interferences between signal paths of the multiple-input signal and signal paths of the multiple-output signal; and

linear processing blocks compensating for the multiple-input multiple-output linear distortions and the effect of interferences between the signal paths of the multiple-input signal and the signal paths of the multiple-output signal.

8. The method of claim 7 , comprising, in the non-linear and linear processing blocks:

processing the multiple-input signal and the multiple-output signal to determine a desired multiple-output signal that pre-compensates for the non-linear and linear distortions;

estimating a non-linear function for each non-linear processing block; and

estimating a linear function for each linear processing block.

9. The method of claim 2 , wherein each of the pre-processing cells of the matrix models a behavior of multi-input multi-output system.

10. The method of claim 9 , wherein each of the pre-processing cells of the matrix include:

a nonlinear processing block to compensate for the multiple-input multiple-output system linear distortions and an effect of interferences between signal paths of the multiple-input signal and signal paths of the multiple-output signal; and

a linear processing block to compensate for the multiple-input multiple-output system linear distortions and the effect of interferences between the signal paths of the multiple-input signal and the signal paths of the multiple-output signal.

11. The method of claim 10 , comprising, in each of the non-linear and linear processing blocks:

processing the multiple-input signal and the multiple-output signal to determine a desired multiple-output signal that pre-compensates for the non-linear and linear distortions;

estimating a non-linear model for each non-linear processing block; and

estimating a linear model for each linear processing block.

12. The method of claim 1 , wherein adjusting the pre-distorted multiple-input signal includes introducing linear and nonlinear distortions on each signal path of the multiple-input signal.

13. The method of claim 12 , wherein adjusting the pre-distorted multiple-input signal further includes introducing interference between each signal path of the multiple-input signal.

14. A pre-compensator for use with a multiple-input and multiple-output transmitter having a multiple-input multiple-output radio frequency (RF) power amplifier, comprising:

a multiple-input of the multiple-input and multiple-output transmitter for receiving a plurality of input signals forming a multiple-input signal;

a matrix of pre-processing cells for generating a pre-distorted multiple-input signal from the received multiple-input signal; and

a multiple-output for feeding the pre-distorted multiple-input signal to the multiple-input and multiple-output transmitter;

wherein the pre-processing cells are configured so as to:

estimate impairments generated by nonlinear crosstalk in the multiple-input and multiple-output RF power amplifier, the nonlinear crosstalk being generated between respective channels of the multiple-input and multiple-output RF power amplifier while being driven by the plurality of input signals; and

adjust the pre-distorted multiple-input signal to compensate for the estimated impairments.

15. The pre-compensator of claim 14 , wherein the adjustment of the pre-distorted multiple-input signal introduces linear and nonlinear distortions on each signal path of the multiple-input signal.

16. The pre-compensator of claim 15 , wherein the adjustment of the pre-distorted multiple-input signal further introduces interference between each signal path of the multiple-input signal.

17. The pre-compensator of claim 14 , wherein each of the pre-processing cells includes nonlinear processing blocks compensating for multiple-input multiple-output nonlinear distortions and an effect of interferences between signal paths of the multiple-input signal and signal paths of the multiple-output signal.

18. The pre-compensator of claim 17 , wherein the nonlinear processing blocks are configured so as to:

process the multiple-input signal and the multiple-output signal to determine a desired multiple-output signal that pre-compensates for the nonlinear distortions; and

estimate a nonlinear function for each nonlinear processing block.

19. The pre-compensator of claim 14 , wherein each of the pre-processing cells includes linear processing blocks compensating for multiple-input multiple-output linear distortions and an effect of interferences between signal paths of the multiple-input signal and signal paths of the multiple-output signal.

20. The pre-compensator of claim 19 , wherein the linear processing blocks are configured so as to:

process the multiple-input signal and the multiple-output signal to determine a desired multiple-output signal that pre-compensates for the linear distortions; and

estimate a linear function for each linear processing block.