I/Q Down-Conversion Image Rejection With Adaptive Decorrelation
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Solution Overview
Problem
Wideband radio communication receivers face significant interference due to I/Q imbalance, particularly in heterodyne architectures, which degrades performance and is challenging to calibrate effectively, leading to sub-optimal results and increased costs.
Innovation Solution
A method employing a Symmetric Adaptive Decorrelation algorithm with an image rejection correction loop, adaptive filter stage, and detector/correlator stage, utilizing adjustable tap-delay lines to mitigate I/Q imbalance, allowing for self-converging optimal parameter settings and reducing calibration needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration algorithms with training sequences are used, then I/Q imbalance compensation is attempted, but implementation cost increases and optimal results are difficult to achieve
Solution Approach 1:
The system performs self-calibration by automatically detecting and compensating for I/Q imbalance without requiring external training sequences or complex calibration algorithms. The compensation is achieved through inherent system operations, eliminating the need for separate calibration procedures and reducing implementation complexity while maintaining high accuracy.
2Reliability
If I/Q imbalance is not compensated, then device complexity remains low, but image signal interference degrades receiver performance
Solution Approach 1:
The patent extracts and compensates for the image signal component separately from the desired signal. By identifying and removing the specific interference caused by I/Q imbalance, the system improves receiver performance without requiring complete redesign of the signal processing architecture, thus limiting the increase in device complexity.
3Adaptability or versatility
If wideband signals are received, then communication capability is enhanced, but image band overlap onto desired signal band increases
Solution Approach 1:
The system dynamically adjusts compensation parameters based on the received signal characteristics and frequency band. By changing the compensation parameters adaptively, the system can effectively handle wideband signals while maintaining high image rejection ratios across different frequency ranges, thus enabling wideband reception without suffering from increased image band overlap.
Data Source
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AI summary
A method, comprising: receiving an input signal comprising at least one sequence of input data samples separated by a sampling period therebetween, the input signal having a desired signal component and an interfering signal component superimposed thereon; applying interfering component estimation processing to the input signal, obtaining as a result a filtered signal comprising a sequence of filtered data samples; subtracting the filtered signal from the input signal and obtaining as a result an output signal comprising a sequence of output data samples; wherein the interfering component estimation processing comprises: a) applying conjugating processing to the input signal, providing a conjugated version of the input signal; b) computing of at least one adaptive signal processing coefficient; c) applying adaptive signal processing to the conjugated version of the input signal using at least one adaptive processing coefficient, wherein computing at least one adaptive signal processing coefficient comprises: i) performing correlation processing between the sequence of output data samples and a conjugated version of the sequence of output data samples and obtaining as a result a sequence of estimates of residual correlation, ii) applying integration processing to the sequence of estimates of residual correlation provided, comprising an integration step parameter and at least one starting point parameter, iii) obtaining at least one computed adaptive signal processing coefficient as a result of applying the integration processing.