Receiver based saturation estimator

• US 7,054,391 B2
• Filed: 05/28/2004
• Issued: 05/30/2006
• Est. Priority Date: 05/30/2003
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: Efficient Channel Coding, Inc. (ViaSat Incorporated)
• Inventors: Thesling, William H.
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US10/857,085
• Publication Number:
  US 20040240578A1
• Time in Patent Office: 732 Days
• Field of Search: 375/221, 375/219, 375/358, 375/340
• US Class Current: 375/340
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A processor-implemented method of estimating the saturation level of a transmitter from a transmitted communication signal received from the transmitter comprises generating a received data signal from the transmitted communication signal received from the transmitter, generating a transmitted data signal from the received data signal that corresponds to the actual data signal generated at the transmitter, comparing the transmitted data signal to the received data signal, and estimating the saturation level of the transmitter based on the comparison of the transmitted data signal to the received data signal.

Claims

1. A processor-implemented method of estimating the saturation level of a transmitter from a transmitted communication signal received from the transmitter, comprising:

filtering the transmitted communication signal to generate a received symbol sequence;

decoding the received symbol sequence to recover data;

determining if the data is error free;

if the data is error free, then;

generating a transmitted symbol sequence;

comparing the transmitted symbol sequence to the received symbol sequence; and

estimating the saturation level of the transmitter based on the comparison of the transmitted symbol sequence to the received symbol sequence.

2. The method of claim 1, wherein comparing the transmitted symbol sequence to the received symbol sequence comprises:

generating a plurality of transmitter saturation transfer functions, each transmitter saturation transfer function corresponding to a saturation level;

filtering the transmitted symbol sequence to generate a communication signal;

inputting the communication signal into each transmitter saturation transfer function to generate a plurality of estimated transmitted communication signals;

filtering the plurality of estimated transmitted communication signals to generate a plurality of estimated received symbol sequences; and

comparing each of the estimated received symbol sequences to the received symbol sequence.

3. The method of claim 2, wherein comparing each of the estimated received symbol sequences to the received symbol sequence comprises generating a correlation coefficient for each of the comparisons of the estimated received symbol sequences to the received symbol sequence.

4. The method of claim 3, further comprising:

determining if saturation level of the transmitter is below a threshold; and

transmitting an instruction to the transmitter to increase transmission power if the saturation level of the transmitter is determined to be below the threshold.

5. The method of claim 4, further comprising transmitting an instruction to the transmitter to decrease a transmission data rate if the saturation level of the transmitter is determined to be above the threshold.

6. The method of claim 3, wherein estimating the saturation level of the transmitter based on the comparison of the transmitted symbol sequence to the received symbol sequence comprises:

determining the highest correlation coefficient generated; and

interpolating between at least the saturation level corresponding to the highest correlation coefficient generated at least one other saturation level.

7. The method of claim 3, wherein generating a correlation coefficient for each of the comparisons of the estimated received symbol sequences to the received symbol sequence comprises:

defining a saturation trajectory;

defining a set equidistant points on the saturation trajectory; and

setting each of the equidistant points to an interpolation index.

8. The method of claim 2, wherein the transmitter saturation transfer functions correspond to amplitude distortion.

9. The method of claim 2, wherein the transmitter saturation transfer functions correspond to phase delay.

10. The method of claim 1, wherein comparing the transmitted symbol sequence to the received symbol sequence comprises generating a linear average of the transmitted symbol sequence to the received symbol sequence, and wherein estimating the saturation level of the transmitter based on the comparison of the transmitted symbol sequence to the received symbol sequence comprises estimating the saturation level of the transmitter based on the linear average.

11. The method of claim 1, further comprising:

determining if the saturation level of the transmitter is below a threshold;

transmitting an instruction to the transmitter to increase transmission power if the saturation level of the transmitter is determined to be below the threshold; and

transmitting an instruction to the transmitter to decrease a transmission data rate if the saturation level of the transmitter is determined to be above the threshold.

12. The method of claim 1, wherein the transmitter is a block-up converter.

13. The method of claim 1, wherein generating the transmitted symbol sequence comprises generating a transmitted symbol sequence that is 180°

from an optimum symbol timing.

14. The method of claim 2, wherein generating a plurality of transmitter saturation transfer functions, each transmitter saturation transfer function corresponding to a saturation level comprises:

defining a saturation trajectory;

defining a set equidistant points on the saturation trajectory; and

generating the plurality of transmitter saturation transfer functions at levels corresponding to the equidistant points on the saturation trajectory.

15. The method of claim 2, wherein generating a plurality of transmitter saturation transfer functions comprises:

interrogating one or more transmitters over a communication link to obtain transmitter transfer function data; and

generating the plurality of transmitter saturation transfer functions based on the transmitter transfer function data obtained by the interrogation.

16. A processor-implemented method of estimating the saturation level of a transmitter from a transmitted communication signal received from the transmitter, comprising:

generating a received data signal from the transmitted communication signal received from the transmitter;

generating a transmitted data signal from the received data signal that corresponds to the actual data signal generated at the transmitter;

comparing the transmitted data signal to the received data signal; and

estimating the saturation level of the transmitter based on the comparison of the transmitted data signal to the received data signal.

17. The method of claim 16, wherein comparing the transmitted data signal to the received data signal comprises:

generating a plurality of transmitter saturation transfer functions, each transmitter saturation transfer function corresponding to a saturation level;

inputting the transmitted data signal into each of the transmitter saturation transfer functions to generate a plurality of estimated transmitted communication signals;

generating a plurality of estimated received data signals from the estimated transmitted communication signals; and

comparing each of the estimated received data signals to the received data signal.

18. The method of claim 16, wherein comparing each of the estimated received data signals to the received data signal comprises generating a correlation coefficient for each of the comparisons of the estimated received data signals to the received data signal.

19. The method of claim 16, further comprising:

determining if the saturation level of the transmitter is below a threshold;

transmitting an instruction to the transmitter to increase transmission power if the saturation level of the transmitter is determined to be below the threshold; and

transmitting an instruction to the transmitter to decrease a transmission data rate if the saturation level of the transmitter is determined to be above the threshold.

20. The method of claim 18, wherein estimating the saturation level of the transmitter based on the comparison of the transmitted data signal to the received data signal comprises:

determining the highest correlation coefficient generated; and

interpolating between at least the saturation level corresponding to the highest correlation coefficient generated at least one other saturation level.

21. The method of claim 17, wherein the transmitter saturation transfer functions correspond to amplitude distortion.

22. The method of claim 17, wherein the transmitter saturation transfer functions correspond to phase delay.

23. The method of claim 17, wherein inputting the transmitted data signal into each of the transmitter saturation transfer functions to generate a plurality of estimated transmitted communication signals comprises:

performing transmitter signal processing on the transmitted data signal to generate a communication signal; and

inputting the communication signal into each of the transmitter saturation transfer functions to generate the plurality of estimated transmitted communication signals.

24. The method of claim 16, wherein comparing the transmitted data signal to the received data signal comprises generating a linear average of the transmitted data signal to the received data signal, and wherein estimating the saturation level of the transmitter based on the comparison of the transmitted data signal to the received data signal comprises estimating the saturation level of the transmitter based on the linear average.

25. The method of claim 17, wherein generating a plurality of transmitter saturation transfer functions, each transmitter saturation transfer function corresponding to a saturation level comprises:

defining a saturation trajectory; and

defining a set equidistant points on the saturation trajectory;

generating the plurality of transmitter saturation transfer functions at levels corresponding to the equidistant points on the saturation trajectory.

26. The method of claim 17, wherein generating a transmitted data signal from the received data signal that corresponds to the actual data signal generated at the transmitter comprises generating a transmitted symbol sequence that is 180°

from an optimum symbol timing.

27. A receiver-based saturation estimator for estimating the saturation level of a transmitter from a transmitted communication signal received from the transmitter, comprising:

means for generating a received data signal from the transmitted communication signal received from the transmitter;

means for generating a transmitted data signal from the received data signal that corresponds to an actual data signal generated at the transmitter;

means for comparing the transmitted data signal to the received data signal; and

means for estimating the saturation level of the transmitter based on the comparison of the transmitted data signal to the received data signal.

28. The saturation estimator of claim 27, further comprising means for determining if saturation level of the transmitter is below a threshold, and for transmitting an instruction to the transmitter to increase transmission power if the saturation level of the transmitter is determined to be below the threshold, and for transmitting an instruction to the transmitter to decrease a transmission data rate if the saturation level of the transmitter is determined to be above the threshold.

29. A receiver-based saturation estimator, comprising:

a first receiver processor operable to receive a transmitted communication signal from a transmitter and generate a received data signal from the transmitted communication signal received from the transmitter;

a transmit data processor operable to generate a transmitted data signal from the received data signal that corresponds to the actual data signal generated at the transmitter; and

a saturation estimator processor operable to compare the transmitted data signal to the received data signal and estimate the saturation level of the transmitter based on the comparison of the transmitted data signal to the received data signal.

30. The receiver-based saturation estimator of claim 29, wherein the saturation estimator comprises:

a plurality of transmitter saturation transfer function conditioners, each transmitter saturation transfer function conditioners corresponding to a saturation level and operable to receive the transmitted data signal and generate an estimated transmitted communication signal;

a second receiver processor operable to receive each of the estimated transmitted communication signal and generate a plurality of estimated received data signals from the estimated transmitted communication signals; and

correlation processors operable to correlate the estimated received data signals to the received data signal and generate correlation coefficients.

31. The receiver-based saturation estimator of claim 29, further comprising a receiver controller operable to determining if saturation level of the transmitter is below a threshold, and to transmit an instruction to the transmitter to increase transmission power if the saturation level of the transmitter is determined to be below the threshold, and to transmit an instruction to the transmitter to decrease a transmission data rate if the saturation level of the transmitter is determined to be above the threshold.

32. The receiver-based saturation estimator of claim 31, wherein the transmitter saturation transfer function conditioners correspond to amplitude distortion.

33. The receiver-based saturation estimator of claim 31, wherein the saturation levels for each transmitter saturation transfer function conditioners are equidistant along a saturation trajectory.

34. The receiver-based saturation estimator of claim 31, wherein the first receiver processor is further operable to generate a transmitted symbol sequence that is 180°

from an optimum symbol timing.

35. The receiver-based saturation estimator of claim 31, wherein the second receiver processor is operable to interrogate one or more transmitters over a communication link to obtain transmitter transfer function data, and generate a plurality of transmitter saturation transfer functions based on the transmitter transfer function data obtained by the interrogation.

36. A processor data signal for adjusting a transmitter transmission power level and embodied in a carrier wave, comprising a transmitter instruction operable to cause the transmitter to increase the transmission power level if a saturation level of the transmitter is determined to be below a threshold, wherein the saturation level of the transmitter has been determined at a receiver system, the determination based on a modulation characteristic of a transmitted communication signal received at the receiver system from the transmitter.