Receiver based transmission characteristic estimator

• US 7,634,021 B2
• Filed: 11/17/2008
• Issued: 12/15/2009
• Est. Priority Date: 05/30/2003
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Thesling, William H.
• Primary Examiner(s): Bayard; Emmanuel
• Application Number:
  US12/272,569
• Publication Number:
  US 20090067538A1
• Time in Patent Office: 393 Days
• Field of Search: 375/340, 375/221, 375/219, 375/295, 375/358
• US Class Current: 375/295
• 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 device for estimating a characteristic of at least one of a transmitter or a transmission medium for a received communication signal transmitted from the transmitter, the device comprising:

a signal processor unit configured to filter the received communication signal to generate a received symbol sequence;

a data processor unit, communicatively coupled with the signal processor unit, and configured to decode the received symbol sequence to recover data; and

an estimator unit, communicatively coupled with the data processor unit, and configured to;

generate a transmitted symbol sequence based on the recovered data;

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

estimate the characteristic of at least one of the transmitter or transmission medium based on the comparison of the transmitted symbol sequence to the received symbol sequence.

2. The device of claim 1, wherein to compare the transmitted symbol sequence to the received symbol sequence, the estimator unit is configured to:

generate a plurality of characteristic transfer functions;

input the communication signal into each characteristic transfer function to generate a plurality of estimated transmitted communication signals;

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

compare each of the estimated received symbol sequences to the received symbol sequence, wherein the estimated received symbol sequences comprise the transmitted symbol sequence.

3. The device of claim 2, wherein to compare each of the estimated received symbol sequences to the received symbol sequence, the estimator unit is configured to generate a correlation coefficient for each of the comparisons of the estimated received symbol sequences to the received symbol sequence.

4. The device of claim 2, further comprising:

an interrogator unit, communicatively coupled with the estimator unit, and configured to;

interrogate one or more other transmitters over a communication link to obtain the characteristic transfer function data; and

generate the plurality of characteristic transfer functions based on the characteristic transfer function data obtained by the interrogation.

5. The device of claim 1, wherein,

to compare the transmitted symbol sequence to the received symbol sequence, the estimator unit is configured to generate an average comparison of the transmitted symbol sequence to the received symbol sequence over time;

and

to estimate the characteristic, the estimator unit is configured to estimate the characteristic of the transmitter based on the average.

6. The device of claim 1, wherein the estimator unit is further configured to:

determine when the characteristic crosses a threshold; and

trigger the device to transmit an instruction to the transmitter to modify transmission based at least in part on the determination.

7. The device of claim 1, wherein the data processing unit is further configured to:

determine whether the recovered data is error free; and

control the estimator unit to generate the transmitted symbol sequence based at least in part on whether the recovered data is determined to be error free.

8. The device of claim 1, wherein the characteristic comprises a saturation level.

9. A processor-implemented method of estimating a characteristic of at least one of a transmitter or a transmission medium, the method comprising:

receiving a communication signal transmitted from a transmitter;

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

decoding the received symbol sequence to recover data;

generating a transmitted symbol sequence based on the recovered data;

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

estimating the characteristic of the transmitter or transmission medium based on the comparison of the transmitted symbol sequence to the received symbol sequence.

10. The method of claim 9, further comprising:

determining when the characteristic crosses a threshold; and

transmitting data identifying the characteristic exceeding the threshold.

11. The method of claim 10, wherein the transmitted data comprises an instruction to modify power at the transmitter.

12. The method of claim 10, wherein the transmitted data comprises an instruction to modify a data rate at the transmitter.

13. The method of claim 10, wherein the characteristic comprises a saturation level.

14. The method of claim 9, further comprising:

analyzing the recovered data for errors; and

triggering the generating step based on the error analysis.

15. A device for estimating a characteristic of at least one of a transmitter or a transmission medium for a received communication signal transmitted from a transmitter, the device comprising:

a signal processor unit configured to demodulate the received communication signal to generate a received data signal;

a data processor unit, coupled with the signal processor unit, and configured to decode the received data signal to recover data corresponding to data generated at the transmitted; and

an estimator unit, coupled with the data processor unit, and configured to;

generate a transmitted data signal based on the recovered data;

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

estimate the characteristic of at least one of the transmitter or transmission medium based on the comparison of the transmitted data signal to the received data signal.

16. The device of claim 15, wherein the received data signal generated by the signal processor unit comprises a received symbol sequence.

17. The device of claim 16, wherein the transmitted data signal generated by the estimator unit comprises a transmitted symbol sequence corresponding to data generated at the transmitter.

18. The device of claim 15, wherein the received data signal generated by the signal processor unit comprises a digitized version of the received communication signal.

19. The device of claim 15, wherein the transmitted data signal generated by the estimator unit comprises an estimation of a digitized version of a transmitted communication signal before the characteristic modifies the transmitted communication signal.

20. A processor-implemented method for estimating a characteristic of at least one of a transmitter or a transmission medium, the method comprising:

digitizing a received communication signal to generate a digitized version of the received communication signal;

decoding the digitized version of the received communication signal to recover data corresponding to data generated at the transmitter;

generating a digitized version of a transmitted communication signal based on the recovered data;

comparing the digitized version of the transmitted communication signal to the digitized version of the received communication signal; and

estimating the characteristic of at least one of the transmitter or transmission medium based on the comparison of the digitized version of the transmitted communication signal to the digitized version of the received communication signal.

21. The method of claim 20, further comprising:

receiving the communication signal in analog form.

22. The method of claim 20, wherein the digitized version of the received communication signal comprises a received symbol sequence.

23. The method of claim 20, further comprising, wherein the digitized version of the transmitted communication signal comprises a symbol sequence corresponding to data generated at the transmitter.

24. A processor for estimating a characteristic of at least one of a transmitter or a transmission medium for a received communication signal transmitted from the transmitter, the processor configured to:

receive a data signal corresponding to the received communication signal;

decode the received data signal to recover data corresponding to data generated at the transmitter;

generate a transmitted data signal based on the recovered data;

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

estimate the characteristic of at least one of the transmitter or transmission medium based on the comparison of the transmitted data signal to the received data signal.

25. The processor of claim 24, wherein,

the received data signal comprises a received symbol sequence;

and

the transmitted data signal comprises a transmitted symbol sequence corresponding to data generated at the transmitter.

26. The processor of claim 24, wherein,

the received data signal comprises a digitized version of the received communication signal;

and

the transmitted data signal comprises an estimation of a digitized version of a communication signal generated at the transmitter before the characteristic modifies the digitized version of communication signal.

27. A system for estimating a characteristic of at least one of a transmitter or a transmission medium, the system comprising:

a transmitter configured to;

generate data for a communication signal; and

transmit the communication signal;

a receiver, in communication with the transmitter, and configured to;

receive the transmitted communication signal;

digitize the received communication signal to generate a digitized version of the received communication signal;

decode the digitized version of the received communication signal to recover data corresponding to the generated data at the transmitter;

generate a digitized version of a transmitted communication signal based on the recovered data;

compare the digitized version of the transmitted communication signal to the digitized version of the received communication signal; and

estimate the characteristic of at least one of the transmitter or the transmission medium based on the comparison of the digitized version of the transmitted communication signal to the digitized version of the received communication signal.

28. The system of claim 27, wherein,

the transmitter comprises a user terminal;

and

the receiver comprises a hub.

29. The system of claim 27, wherein the transmitter communicates with the receiver via a satellite.

30. The system of claim 27, wherein the transmitter wirelessly communicates with the receiver.

31. The system of claim 27, wherein the receiver is further configured to:

determine when the characteristic exceeds a threshold; and

transmit data identifying the characteristic exceeding the threshold.

32. The system of claim 31, wherein the transmitted data comprises an instruction to modify power at the transmitter and to modify a data rate at the transmitter.