Frequency Offset Estimation for Filtered Signals with Destroyed Phase
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Solution Overview
Problem
Conventional frequency offset estimation methods fail to accurately estimate frequency offsets in filtered signals with destroyed phase information, leading to inaccurate compensation and potential divergence in automatic frequency control, especially at low carrier-to-interference ratios.
Innovation Solution
A method involving a signal transceiver with a filter and a reference signal generator that derives third filter coefficients from first filter coefficients to create an artificial signal with preserved phase information, allowing for accurate frequency offset estimation using both inphase and quadrature-phase components, even at low carrier-to-interference ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter filters the original signal to obtain a filtered signal with higher C/I ratio, then the signal quality is improved, but the phase and frequency information is lost
Solution Approach 1:
The patent segments the filtering process into two distinct paths: one path applies the filter to obtain the filtered signal with high C/I ratio, while the other path uses derived filter coefficients to generate a reference signal that preserves phase information. This segmentation allows both objectives to be achieved simultaneously without compromising either signal quality or phase information integrity.
Solution Approach 2:
The patent introduces an intermediary reference signal generated by filtering the original signal with derived coefficients. This reference signal acts as a mediator that bridges the filtered signal and the original signal, providing the necessary phase information for frequency offset estimation while maintaining the benefits of filtering.
2Measurement precision
If frequency offset estimation is performed on the original signal with low C/I ratio, then phase information is available, but the estimation accuracy deteriorates due to interference
Solution Approach 1:
The reference signal serves as an intermediary that carries phase information from the original signal while being generated in a way that preserves this information. By using this intermediary reference signal combined with the filtered signal, the system achieves accurate frequency offset estimation without being degraded by interference affecting the original signal.
Solution Approach 2:
The patent changes the parameters of the filtering process by deriving a second set of filter coefficients from the first set, specifically designed to generate a reference signal that maintains phase information. This parameter transformation allows the system to extract frequency offset information accurately even when the original signal is heavily interfered with.
3Device complexity
If conventional frequency offset estimation is used with filtered signal, then device complexity is reduced, but frequency offset estimation fails due to destroyed phase information
Solution Approach 1:
The patent segments the signal processing into filtering and reference signal generation components, where the filter coefficients are reused to create a reference signal. This segmentation maintains relatively simple device complexity while ensuring reliable frequency offset estimation by preserving the necessary phase information through the reference signal path.
Data Source
AI summary
The invention provides a method for frequency offset estimation according to a filtered signal with destroyed phase information. In one embodiment, a filter filters an original signal according to a series of first filter coefficients to obtain a first-channel component of the filtered signal, and filters the original signal according to a series of second filter coefficients to obtain a second-channel component of the filtered signal. A series of third filter coefficients are first derived from the first filter coefficients. The original signal is then filtered according to the third filter coefficients to obtain a reference signal. A first frequency offset value is estimated according to the first-channel component of the filtered signal and the reference signal, wherein the first-channel component of the filtered signal is a first-channel component of an artificial signal, and the reference signal is a second-channel component of the artificial signal.