Frequency-Shifted PIM Estimation for Lower-Rate RF Sampling
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Solution Overview
Problem
Conventional PIM reduction algorithms in RF systems require high power consumption and complex design due to the need for a sampling rate higher than 2*ΔFc to avoid aliasing, which increases the complexity and energy usage of PIM filter coefficient estimation.
Innovation Solution
Implementing frequency shifting of signal components to reduce the frequency spacing between TX carrier signals, allowing the PIM filter coefficient estimation algorithm to run at a lower sampling rate of 2*ΔF'c, where ΔF'c is smaller than ΔFc, thereby reducing power consumption and design complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling rate is increased to higher than 2*ΔFc to avoid aliasing, then the PIM filter coefficient estimation accuracy is improved, but the power consumption and design complexity increase
Solution Approach 1:
The patent applies frequency shifting to change the frequency parameters of the signal components. By shifting the frequency of TX carrier signals and RX carrier signals, the frequency spacing ΔF'c is reduced, which allows the sampling rate to be lowered from 2*ΔFc to 2*ΔF'c while maintaining adequate estimation accuracy. This parameter transformation resolves the contradiction by finding an optimal balance point.
Solution Approach 2:
The patent introduces dynamic frequency shifting that can be adjusted based on the specific signal conditions. The frequency shift amount is optimized to achieve the desired reduction in sampling rate while maintaining performance. This dynamic adjustment allows the system to adaptively balance between accuracy and power consumption requirements.
2Measurement precision
If the sampling rate is increased to higher than 2*ΔFc to avoid aliasing, then the PIM filter coefficient estimation accuracy is improved, but the design complexity increases
Solution Approach 1:
By transforming the frequency parameters through frequency shifting, the patent reduces the required sampling rate from 2*ΔFc to 2*ΔF'c. This parameter change simplifies the design requirements for the sampling system, ADCs, and processing architecture, thereby reducing overall design complexity while maintaining adequate estimation accuracy.
Solution Approach 2:
The dynamic frequency shifting mechanism allows the system to optimize the sampling rate based on actual signal conditions. This flexibility enables simpler design configurations to be used in many practical scenarios, reducing the need for overly complex high-speed sampling infrastructure.
3Use of energy by moving object
If frequency shifting is applied to reduce frequency spacing, then the sampling rate requirement is reduced, but additional signal processing complexity is introduced
Solution Approach 1:
The frequency shifting operation is designed to be computationally efficient, using standard signal processing techniques that can be implemented with moderate complexity. The shift amount is optimized to achieve the desired sampling rate reduction without excessive processing overhead. The dynamic nature of the frequency shifting allows it to adapt to different signal conditions, maintaining efficiency across various operating scenarios.
Solution Approach 2:
By carefully selecting the frequency shift parameters, the patent achieves a balance where the processing complexity of frequency shifting is offset by the reduction in sampling rate requirements. The parameter optimization ensures that the additional processing steps are minimal compared to the savings achieved in the sampling and power consumption domains.
Data Source
AI summary
A system for reducing or eliminating PIM interference in an RX signal is disclosed. The system is configured to use RX and TX signals to generate a frequency-shifted output that includes a RX carrier signal component of the RX signal, as well as first and second TX carrier signal components of the TX signal, positioned in a frequency spectrum so that a frequency spacing between the first and the second TX carrier signal components and a frequency spacing between the RX carrier signal component and a closest one of the first and the TX second carrier signal components is smaller than a frequency spacing between the first and the second TX carrier signal components in the TX signal. The system may then use the frequency-shifted output to generate an estimate of a PIM signal component in the RX signal.