Beamforming Calibration via Synchronized Noise Reference
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Solution Overview
Problem
Current beamforming systems face challenges in calibrating reception channels with fractional delays and achieving precise delay compensation, leading to inefficient resource usage and reduced signal quality due to the need for complex interpolation filters and long temporal responses, especially when dealing with broadband and multimode applications.
Innovation Solution
A calibration method involving spectral analysis and the use of noise as a reference signal, synchronized across channels, to measure and correct differences in amplitude and phase, reducing resource requirements and improving accuracy by simplifying the calibration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex interpolation filters are used to achieve precise fractional delay compensation, then delay compensation precision is improved, but computational complexity and resource usage increase
Solution Approach 1:
The patent segments the delay compensation task into two parts: integer delay compensation using simple buffering and fractional delay compensation using interpolation filters. This segmentation allows the majority of the delay (integer part) to be handled by simple memory operations, while only the fractional part requires complex filtering, thus reducing overall computational complexity while maintaining precision.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing interpolation filter coefficients for common fractional delay values. This allows the system to quickly switch between pre-computed filters rather than calculating interpolation coefficients in real-time, reducing computational burden during actual delay compensation operations.
2Measurement precision
If long temporal response filters are used to ensure precise delay across broadband signals, then delay precision is improved, but filter duration and processing time increase
Solution Approach 1:
The patent implements dynamic filter selection where the interpolation filter order and type are adjusted based on the specific fractional delay value and signal bandwidth requirements. For smaller fractional delays, lower-order filters are used, reducing temporal response duration. For larger fractional delays or broader bandwidths, higher-order filters are selected to maintain precision, thus dynamically optimizing the trade-off between precision and filter duration.
3Measurement precision
If calibration is performed separately for each reception channel, then calibration accuracy is improved, but processing time and resource usage increase
Solution Approach 1:
The patent merges the calibration process by using a common reference signal that is distributed to all reception channels simultaneously. By correlating the received reference signal with the known transmitted reference signal across all channels, the system performs calibration for multiple channels in parallel rather than sequentially, significantly reducing processing time while maintaining accuracy through the use of a unified reference.
Solution Approach 2:
The patent implements feedback by measuring the correlation between the received reference signal and the transmitted reference signal, then using this correlation information to adjust and optimize the calibration parameters. The feedback loop allows the system to iteratively improve calibration accuracy by refining the correlation-based measurements, ensuring precise channel equalization while minimizing processing time through efficient feedback utilization.
Data Source
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AI summary
The present invention relates to a method for calibrating a beamforming system comprising P receiving channels, each designed to receive signals from a respective antenna, the calibration method comprising: - the injection into the time domain of a replica of a digital signal used to constitute a calibration signal, this replica being synchronized with the spectral analysis means, - the passage through the spectral domain of this digital signal by means identical to those applied to the signals of the receiving channels, said identical means being synchronized with each other, - the measurement of values of the reference signal and of values of the signal propagated on the receiving channel, and - the deduction of the difference between the reference signal and the propagated signal as a function of the measured values.