Receiver-based frequency response estimation

1. A system for pre-distorting a signal, the system comprising:

a plurality of subscriber terminals located within a subscriber spot beam of a multi-beam satellite, each of the plurality of subscriber terminals configured to:

receive a first spot beam signal transmitted from a gateway device via the multi-beam satellite;

buffer a digitized representation of the first wireless spot beam signal comprising a sequence of symbols;

decode the sequence of symbols to recover a set of data;

regenerate a version of the transmitted first wireless spot beam signal from the recovered set of data;

compare a first spectral estimate for the buffered sequence of symbols to a second spectral estimate generated from the regenerated version of the first spot beam signal to create comparison data, the spectral estimates identifying signal amplitudes and phases at each of a plurality of analysis frequencies; and

transmit the comparison data to the gateway device; and

the gateway device, in communication with the plurality of subscriber terminals via the multi-beam satellite, and configured to:

receive the comparison data from of the plurality of subscriber terminals;

schedule transmissions to a first subset of subscriber terminals of the plurality of subscriber terminals in a second spot beam signal to be transmitted to the plurality of subscriber terminals; and

pre-distort the second spot beam signal based at least in part on the received comparison data from the first subset of subscriber terminals to compensate for frequency responses of signals transmitted to the first subset plurality of subscriber terminals, and wherein the pre-distortion is based on an average of received comparison data and excludes the received comparison data from a second subset of subscriber terminals of the plurality of subscriber terminals when the scheduled transmissions of the second spot beam signal are not directed at the second subset of subscriber terminals.

2. The system of claim 1 , wherein each of the plurality of subscriber terminals are configured to generate comparison data comprising one or more measurements of amplitude differences between the first spectral estimate and the second spectral estimate.

3. The system of claim 1 , wherein each of the plurality of subscriber terminals are configured to generate comparison data comprising one or more measurements of phase differences between the first spectral estimate and the second spectral estimate.

4. The system of claim 1 , wherein the gateway device is configured to pre-distort the second spot beam signal by filtering the second spot beam signal to modify an amplitude and phase of a subset of spectral components of the second spot beam signal.

5. The system of claim 1 , wherein each of the plurality of subscriber terminals are configured to transmit the comparison data to the gateway device via a landline.

6. The system of claim 1 , wherein each of the plurality of subscriber terminals are configured to transmit the comparison data to the gateway device via the satellite in a pad portion of a data packet.

7. The system of claim 1 , wherein the gateway device is not located within the subscriber spot beam.

8. A method of pre-distorting a signal at a gateway device in communication with a plurality of subscriber terminals located within a subscriber spot beam of a multi-beam satellite, the method comprising:

receiving spectral comparison data from the plurality of subscriber terminals, wherein the spectral comparison data from each subscriber terminal of the plurality of subscriber terminals is generated by comparing a spectral estimate for a buffered digitized sequence of symbols of a first spot beam signal received at the each subscriber terminal to a spectral estimate of data generated from a regenerated version of the sequence of symbols, the regenerated version of the sequence of symbols regenerated from a recovered set of data generated by decoding the buffered digitized sequence of symbols, the spectral estimates identifying signal amplitudes and phases at each of a plurality of analysis frequencies;

scheduling transmissions to a first subset of subscriber terminals of the plurality of subscriber terminals in a second wireless spot beam signal to be transmitted to the plurality of subscriber terminals; and

pre-distorting the second spot beam signal based at least in part on the received spectral comparison data from the first subset of subscriber terminals to compensate for frequency responses of signals transmitted to the first subset of subscriber terminals, and wherein the pre-distorting is based on an average of received spectral comparison data and excludes the received spectral comparison data from a second subset of subscriber terminals of the plurality of subscriber terminals when the scheduled transmissions of the second spot beam signal are not directed at the second subset of subscriber terminals.

9. The method of claim 8 , further comprising:

generating the spectral estimate for the buffered digitized sequence of symbols; and

generating the spectral estimate of data generated from the recovered set of data.

10. The method of claim 9 , wherein, the spectral estimate for the buffered digitized sequence of symbols and the spectral estimate of data from the recovered set of data are each generated using a fast Fourier transform.

11. The method of claim 8 , wherein the pre-distorting step comprises:

filtering the second spot beam signal to be transmitted from the gateway device to modify an amplitude of at least a subset of spectral components of the second spot beam signal to be transmitted.

12. The method of claim 8 , further comprising:

estimating a frequency response of channels of the first spot beam using the comparison of spectral estimations.

13. The method of claim 12 , further comprising:

determining that the frequency response comprises a nonlinear output; and

identifying pre-distortion filter coefficients using a look-up table, wherein the identified pre-distortion filter coefficients are used in the pre-distorting step.