Adaptive Interference Cancellation for Single- and Multi-Tone Receivers
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Solution Overview
Problem
Existing methods for canceling single-tone or multi-tone interference in communication receivers face challenges such as low precision, high computing complexity, and poor tracking accuracy, particularly in single carrier and OFDM systems, due to limitations in frequency detection and processing techniques like DFT and DCT.
Innovation Solution
A method and system that transform the received signal to the frequency domain, estimate the interference frequency and amplitude, generate a reference signal using an adaptive algorithm, and subtract it from the received signal to cancel interference, reducing computing complexity and improving tracking accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DFT or DCT is used to detect interference frequency in frequency domain, then frequency detection capability is provided, but estimation precision is low when point number is small and computing complexity is high when point number is large
Solution Approach 1:
The patent uses an adaptive algorithm that dynamically adjusts the reference signal parameters (frequency, amplitude, phase) based on the error signal computed from the correlation between the received signal and the reference signal. This dynamic adaptation allows the system to track interference signals with changing characteristics without requiring high-point DFT/DCT transforms, thus reducing computing complexity while maintaining precision.
Solution Approach 2:
The patent implements a feedback mechanism where the error signal (correlation between received signal and reference signal) is used to update the reference signal parameters iteratively. This feedback loop enables continuous refinement of interference signal estimation without requiring high computing resources for frequency domain transforms, resolving the contradiction between precision and complexity.
2Object-affected harmful factors
If notch filter is used to remove interference signal, then interference cancellation is achieved, but transition zone impacts data of adjacent sub-carriers leading to performance degradation
Solution Approach 1:
The patent extracts the interference signal characteristics (frequency, amplitude, phase) to generate a reference signal that models the interference. By subtracting this reference signal from the received signal, the interference is removed without affecting adjacent sub-carriers, unlike notch filters that have transition zones. This extraction approach eliminates the harmful side effects while maintaining system performance.
Solution Approach 2:
The patent creates a copy of the interference signal through the reference signal, which is generated to match the interference characteristics. This copy is then subtracted from the received signal to cancel the interference. The copying approach allows precise interference removal without the transition zone problems of notch filters, preserving adjacent sub-carrier integrity.
3Measurement precision
If time domain difference processing is used to extract common phase, then interference frequency can be obtained, but computing complexity is very high due to matrix operation
Solution Approach 1:
The patent replaces the complex matrix operations of time domain difference processing with a simpler correlation-based adaptive algorithm. Instead of performing matrix operations to extract common phase, the system uses correlation between the received signal and a reference signal to detect interference frequency and update parameters, significantly reducing computing complexity while maintaining detection precision.
4Measurement precision
If advanced signal processing technologies such as wavelet basis are used, then frequency estimation precision is improved, but computing complexity becomes too high for practical receivers
Solution Approach 1:
The patent uses a computationally efficient adaptive algorithm that provides sufficient frequency estimation precision for practical receivers. Instead of employing complex wavelet basis transformations, the system uses a simple correlation-based approach with iterative parameter updates that achieves the required precision at much lower computational cost, making it suitable for practical implementation in receivers.
Data Source
AI summary
A method and system for canceling an interference signal are provided. In the method, a received signal is transformed from a time domain to a frequency domain at relative low precision to obtain an estimated frequency and an estimated amplitude of the interference signal. A reference signal is generated using the estimated frequency and the estimated amplitude. An error signal is generated using the received signal and the reference signal based on minimum correlation criteria. The reference signal is adjusted using the error signal based on an adaptive algorithm. The reference signal is subtracted from the received signal to obtain the useful signal.