Interference resistant method for in-situ operational calibration and compensation of gain and phase variations in antenna array receiver RF and analog front-end electronics
Systems and methods are described for performing interference-resistant calibration and compensation of radio-frequency (RF) and analog front-end electronics of antenna-array based receivers during active operation. Examples of systems and methods are described herein that may provide interference-resistant calibration maintenance and ongoing compensation for changing gain and phase in receiver front-end electronic components, due to manufacturing tolerances and operational and environmental factors such as variations in temperature, humidity, supply voltage, component aging, connector oxidation, mechanical stresses and vibration, and/or maintenance operations such as sparing and swapping of cables, front-end electronics modules, and/or associated circuitry.
1. A method comprising:
applying at least one calibration signal to at least one of a plurality of antenna paths at a location prior to at least one respective analog front-end electronic component of the at least one of the plurality of antenna paths and after at least one respective antenna of the at least one of the plurality of antenna paths;
generating interference-adjusted calibration waveforms based on combining a first plurality of frequency domain data streams generated using sampling signals with at least one second frequency domain data stream generated using the at least one calibration signal;
generating calibration weights based on the generated interference-adjusted calibration waveforms; and
combining further frequency domain data streams received at the plurality of antenna paths with the calibration weights to reduce variations introduced by the at least one respective analog front-end electronic component of the at least one of the plurality of antenna paths, wherein the variations comprise phase variations, amplitude variations, or combinations thereof.
2. The method of claim 1 , wherein the plurality of antenna paths are a first plurality of antenna paths utilizing at least a first plurality of antennas of an antenna array, and the first plurality of frequency domain data streams are generated based on the sampling signals received at a second plurality of antenna paths by a second plurality of antennas of the antenna array.
3. The method of claim 2 , wherein the first plurality of frequency domain data streams are based on sampling interference signals received at the second plurality of antenna paths.
4. The method of claim 3 , wherein a count of the second plurality of antennas is based on an expected number of interference sources.
5. The method of claim 2 , wherein the first plurality of antenna paths and the second plurality of antenna paths comprise respective analog front-end electronic components.
6. The method of claim 2 , wherein the calibration weights are for use with the first plurality of antenna paths, the method further comprising:
generating interference-adjusted calibration waveforms for the second plurality of antenna paths based at least in part on applying the at least one calibration signal to the the second plurality of antenna paths; and
generating calibration weights for use with the second plurality of antenna paths based on the interference-adjusted calibration waveforms for the second plurality of antenna paths.
7. The method of claim 1 , wherein the interference-adjusted calibration waveforms are for a subband of the at least one second frequency domain data stream, and wherein the method further comprising generating further interference-adjusted calibration waveforms for other subbands of the at least one second frequency domain data streams.
8. The method of claim 1 , wherein combining the at least one second frequency domain data streams with the first plurality of frequency domain data streams comprises weighting the first plurality of frequency domain data streams in accordance with cancellation weights to provide a representation of interference.
9. The method of claim 8 , further comprising subtracting the representation of interference from the at least one second frequency domain data streams to provide the interference-adjusted calibration waveforms.
10. The method of claim 8 , further comprising calculating the cancellation weights based on a matrix of data from a first plurality of antenna paths and data from a second plurality of antenna paths.
11. The method of claim 10 , further comprising calculating the cancellation weights based on calibration residuals from the first plurality of antenna paths.
12. The method of claim 1 , further comprising generating multiple snapshots of the interference-adjusted calibration waveforms based on multiple instances of combining the at least one second frequency domain data streams with the first plurality of frequency domain data streams, wherein the generation of the calibration weights based on the interference-adjusted calibration waveforms comprises smoothing the calibration weights over the multiple snapshots.
13. The method of claim 12 , further comprising selecting certain snapshots for inclusion in the smoothing based on a quality metric.
14. The method of claim 1 , wherein generating calibration weights based on the interference-adjusted calibration waveforms further comprises smoothing the calibration weights over multiple frequency bins.
15. The method of claim 14 , further comprising generating sets of interference-adjusted calibration waveforms for multiple subbands, wherein generating the calibration weights based on the interference-adjusted calibration waveforms comprises smoothing the calibration weights over the multiple subbands.
16. A receiver comprising:
a plurality of antenna paths with respective antennas and respective electronic components:
a calibration source configured to apply at least one calibration signal to at least one of the plurality of antenna paths at a location prior to at least one respective electronic component of the at least one of the plurality of antenna paths and after at least one respective antenna of the at least one of the plurality of antenna paths; and
a processor configured to:
combine data streams from an interference subset of respective antenna paths generated using sampling signals with at least one data stream from a calibration subset of the respective antenna paths generated using the at least one calibration signal applied to the calibration subset of the respective antenna paths to generate interference-cancelled calibration waveforms; and
generate calibration weights based on the interference-cancelled calibration waveforms; and
combine further data streams from the calibration subset of the respective antenna paths with the calibration weights to reduce variations introduced by at least one re v electronic component provided in the at least one of the respective antenna paths, wherein the variations comprise phase variations, amplitude variations, or a combination thereof.
17. The receiver of claim 16 , further comprising:
a calibration switch configured to couple the calibration source to the calibration subset of the respective antenna paths.
18. The receiver of claim 17 , wherein the processor is further configured to generate cancellation weights, and wherein the processor is configured to combine the data streams at least in part by weighting the data streams from the interference subset of the respective antenna paths with the cancellation weights.
19. The receiver of claim 18 , wherein the processor is further configured to subtract the weighted data streams from the at least one data stream from the calibration subset of the respective data paths.
20. The receiver of claim 16 , wherein a count of the interference subset of the respective antenna paths is based on an expected count of interferers in a communication system including the receiver.
21. The receiver of claim 16 , wherein the processor is configured to calculate per-snapshot calibration weights, and calculate the calibration weights by smoothing the per-snapshot calibration weights.