APPARATUS AND METHOD FOR REDUCED COMPUTATION AMPLIFIER GAIN CONTROL

• US 20170346507A1
• Filed: 05/24/2016
• Published: 11/30/2017
• Est. Priority Date: 05/24/2016
• Status: Active Grant

• Current Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Original Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Inventors: Becker, Neal D.
• Granted Patent: US 10,230,409 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 2001/0408 with power amplifiers
• CPC Class Codes: H04B 2001/1045 Adjacent-channel interference
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion

Abstract

Signals are received that include a channel band and an adjacent band. The channel band is demodulated to obtain recovered symbols. Cross-correlation between the recovered symbols and the adjacent band is estimated. Adjacent channel interference is estimated, using the estimated cross-correlation of the recovered symbols and the adjacent band. Upon the estimated adjacent channel interference meeting a condition, a back-off command is sent to a transmitter power amplifier.

Claims

1. A method for controlling a transmitter amplifier, comprising:

receiving a frequency band that includes an assigned channel, an adjacent channel, and a communication signal from the transmitter amplifier in the assigned channel, the assigned channel and the adjacent channel being respective sub-bands of the frequency band;

determining cross-correlation coefficients, between the communication signal and the adjacent channel;

estimating an adjacent channel interference, based at least in part on the cross-correlation coefficients; and

upon the estimated adjacent channel interference meeting a given condition, initiating communication of an operating point notice, toward a local control of the transmitter amplifier.

2. The method of claim 1, wherein initiating the communication of the operating point notice comprises wireless transmitting the operating point notice toward the local control.

3. The method of claim 2, wherein wireless transmission of the operating point notice toward the local control includes uplink transmitting, from an earth station, to a satellite, and downlink transmission from the satellite toward the local control.

4. The method of claim 1, wherein:

the adjacent channel is a first adjacent channel,

the cross-correlation coefficients are first adjacent channel cross-correlation coefficients, and

the frequency band includes a second adjacent channel, and wherein the method further comprises;

estimating second adjacent channel cross-correlation coefficients, between the communication signal and the second adjacent channel,

wherein estimating the adjacent channel interference is further based, at least in part, on the second adjacent channel cross-correlation coefficients.

5. The method of claim 1, wherein:

determining cross-correlation coefficients includes demodulating the communication signal to obtain a recovered symbol, and

the cross-correlation coefficients are each associated with a different time offset from the recovered symbol.

6. The method of claim 5, further comprising:

applying a timing interpolation to the first adjacent channel, or the second adjacent channel, or both, the timing interpolation being configured to compensate for delays in demodulating the communication signal.

7. The method of claim 5, wherein:

demodulating the communication signal is configured to form a series of recovered symbols,

a reference time is a periodic reference time that aligns with the recovered symbols, and

the cross-correlation coefficients are each associated with a different time offset between the reference time and the adjacent channel.

8. The method of claim 7, wherein:

estimating adjacent channel interference includes estimating a correlation magnitude, based at least in part on a combination of the cross-correlation coefficients, and

the estimated adjacent channel interference is based at least in part on the estimated correlation magnitude.

9. The method of claim 8, wherein estimating the correlation magnitude is based, at least in part, on maximum-ratio combining of the cross-correlation coefficients.

10. The method of claim 8, wherein the given condition is the estimated adjacent channel interference having a value that is at least a given maximum.

11. The method of claim 7, wherein

the adjacent channel is a first adjacent channel,

the cross-correlation coefficients are first adjacent channel cross-correlation coefficients, and the frequency band further includes a second adjacent channel, and wherein the method further comprises:

generating a set of second adjacent channel cross-correlation coefficients, each of the second adjacent channel cross-correlation coefficients being associated with a different time offset between the reference time and the second adjacent channel,

wherein estimating correlation magnitude is further based, at least in part, on the set of second adjacent band cross-correlation coefficients.

12. The method of claim 11, wherein estimating correlation magnitude is based, at least in part, on maximum-ratio combining of the first adjacent channel cross-correlation coefficients and the second adjacent channel cross-correlation coefficients.

13. The method of claim 7, wherein:

the different time offset between the reference time and adjacent channel comprises a plurality of different time offsets, and

the cross-correlation coefficients comprise a plurality of cross-correlation coefficients, each of the cross-correlation coefficients corresponding to a different time offset among the plurality of different time offsets.

14. The method of claim 7, wherein:

the different time offset between the reference time and adjacent channel comprises at least M different time offsets, and

the cross-correlation coefficients comprise at least M cross-correlation coefficients, each of the at least M cross-correlation coefficients corresponding to a different time offset among M different time offsets.

15. The method of claim 14, further comprising:

sampling the recovered symbol, at a sampling time aligned with the reference time, to obtain a symbol sample;

sampling the adjacent channel to obtain, associated with the symbol sample, a set of M adjacent channel samples, each corresponding to a different one among the N time offsets; and

generating the set of M cross-correlation coefficients, based on multiplying each of the M adjacent channel samples by the symbol sample, to form a corresponding set of M products, each of the M products being a corresponding one of the set of M cross-correlation coefficients.

16. The method of claim 15, wherein:

the adjacent channel is a first adjacent channel,

the frequency band further includes a second adjacent channel,

the set of M adjacent channel samples is a set of M first adjacent channel samples, and

the corresponding M products are M first products, wherein the method further comprises;

sampling the second adjacent channel to obtain, associated with the symbol sample, a set of M second adjacent channel samples, each corresponding to a different one among the M different time offsets; and

generating a set of M second adjacent channel cross-correlation coefficients, based on multiplying each of the M second adjacent channel samples by the symbol sample, to form a corresponding M second products, each of the M second products being a corresponding one of the M second adjacent channel cross-correlation coefficients.

17. The method of claim 14, wherein the set of M cross-correlation coefficients is a first set of M cross-correlation coefficients, wherein the method further comprises:

sampling a first and a second recovered symbol among the series of recovered symbols to obtain a respective first symbol sample and second symbol sample;

sampling the adjacent channel to obtain, associated with the first symbol sample, a first set of M adjacent channel samples, each of the M adjacent channel samples corresponding to one of the different time offsets, relative to the first symbol sample;

multiplying each of the first set of M adjacent channel samples by the first symbol sample to produce a first set of M products;

performing another sampling of the adjacent channel to obtain, associated with the second recovered symbol, a second set of M adjacent channel samples, each of the second set of M adjacent channel samples corresponding to a different one of the M time offsets, relative to second symbol sample among the set of M time offsets;

multiplying each of the second set of M adjacent channel samples by the second symbol sample to form a second set of M products;

adding each product among the second set of M products to a corresponding product among the first set of M products to generate a set of M sum-of-products; and

generating a set of M cross-correlation coefficients, each of the cross-correlation coefficients based at least in part on a corresponding sum-of-products among the set of M sum-of-products.

18. A receiver circuit for controlling a transmitter amplifier back-off, comprising:

a receiver antenna;

a filter coupled to the receiver antenna and configured to pass an assigned channel and an adjacent channel, the assigned channel and the adjacent channel being respective sub-bands of a frequency band;

a cross-correlation coefficient logic, configured to generate a set of cross-correlation coefficients, between the assigned channel and the adjacent channel;

an adjacent channel interference estimation logic, configured to estimate an adjacent channel interference, based at least in part on the set of cross-correlation coefficients; and

an operating point notice logic, configured to generate an operating point notice in response to the estimated adjacent channel interference.

19. The receiver circuit of claim 18, wherein the cross-correlation coefficient logic comprises:

a demodulator logic, configured to demodulate a signal in the assigned channel and output a corresponding recovered symbol stream;

a recovered symbol sampler, configured to sample the recovered symbol stream and generate, for each symbol in the recovered symbol stream, a corresponding symbol sample;

an adjacent channel sampler, configured to sample the adjacent channel at a rate and timing that generates, in association with each symbol sample, M adjacent channel samples, the M adjacent channel samples corresponding to M different time offsets relative to the symbol sample,

wherein the cross-correlation coefficient logic is configured to

multiply a symbol sample among the symbol samples by each of the M corresponding adjacent channel samples, to generate a set of M products,

store the set of M products in a set of M accumulators, to initialize a set of M sums-of-products,

repeat for K iterations an operation that includes

multiply a next symbol sample among the symbol samples by each of the M adjacent channel samples corresponding to the next symbol sample, to generate a new set of M products, and

add the new set of M products to the set of M accumulators, to update the set of M sums-of-products, and

output the content of the set of M accumulators as a set of M cross-correlation coefficients.

20. The receiver circuit of claim 19, wherein the adjacent channel interference estimation logic is configured to estimate the cross-correlation, based at least in part on applying different weightings to the cross-correlation coefficients in the set of cross-correlation coefficients.

21. The receiver circuit of claim 18, further comprising:

a demodulator logic, configured to demodulate a signal in the assigned channel and output a corresponding recovered first symbol and recovered second symbol;

a recovered symbol sampler, configured to sample the recovered first symbol and the recovered second symbol, and generate a corresponding first symbol sample and second symbol sample;

an adjacent channel sampler, configured to sample the adjacent channel at a rate and timing that generates, in association with the first symbol sample, a first set of M adjacent channel samples, corresponding to M different time offsets relative to the first symbol sample, and in association with the first symbol sample a second set of M adjacent channel samples, corresponding to M different time offsets relative to the second symbol sample,

wherein the cross-correlation coefficient logic is configured to

multiply the first symbol sample among the symbol samples by each of the first set of M adjacent channel samples, to generate a first set of M products,

multiply the second symbol sample among the symbol samples by each of the second set of M adjacent channel samples, to generate a second set of M products, a

add each product among the second set of M products to a corresponding product among the first set of M products to generate a set of M sum-of-products, and

generate a set of M cross-correlation coefficients, each of the cross-correlation coefficients based at least in part on a corresponding sum-of-products among the set of M sum-of-products.

22. The receiver circuit of claim 21, further comprising:

a timing interpolator, in the filter or in series with the filter, in the path of the adjacent channel and configured to compensate for a delay in the demodulator logic.