Adaptive Equalizer Fractional Sampling Tap Coefficient Initialization
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Solution Overview
Problem
Existing adaptive equalizers face challenges in determining an appropriate initial tap coefficient value when fractional sampling is used, as the approach from related art may not work correctly, leading to errors in waveform recovery and increased power consumption.
Innovation Solution
An adaptive equalizer that includes a sample buffer for fractional sampling and a processor to specify the position of a training sequence based on correlation values, adjusting the symbol length of the training sequence to ensure that the sampling rate times the symbol length is an integer, allowing for accurate tap coefficient calculation and initial value setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-times oversampling is performed to avoid aliasing and recover the correct waveform, then the waveform recovery accuracy is improved, but the number of taps of the equalizer is doubled and the processing amount increases
Solution Approach 1:
The patent changes the sampling rate parameter from the conventional two-times oversampling to a fractional value between one and two times the symbol rate. This parameter change allows the system to maintain waveform recovery accuracy while reducing the number of equalizer taps and processing complexity, directly resolving the contradiction between measurement precision and device complexity
2Measurement precision
If the sampling rate is increased to two times the symbol rate to avoid aliasing, then the waveform recovery is improved, but the power consumption increases
Solution Approach 1:
The patent applies parameter change by setting the sampling rate to a fractional value between one and two times the symbol rate rather than using the conventional two-times oversampling. This parameter optimization reduces the sampling frequency, which directly reduces the processing load and power consumption while maintaining sufficient waveform recovery accuracy through the corrected tap coefficient initialization method
3Device complexity
If fractional sampling is used to reduce the number of taps and processing amount, then the equalizer complexity is reduced, but the ability to correctly determine the initial tap coefficient is lost
Solution Approach 1:
The patent applies preliminary action by providing a specific method to determine the initial tap coefficient before the adaptive equalization process begins. The method uses correlation between received signals and training sequences to calculate the initial tap coefficient, ensuring reliable initialization even with fractional sampling. This preliminary preparation resolves the reliability issue while maintaining the complexity reduction benefits of fractional sampling
Solution Approach 2:
The patent introduces an intermediary calculation method that uses correlation operations between the received signal and known training sequences to determine the initial tap coefficient. This intermediary approach bridges the gap between fractional sampling and reliable coefficient determination, allowing the system to use reduced sampling rates while maintaining initialization accuracy through this intermediate correlation-based calculation step
4Volume of moving object
If the number of taps is reduced through fractional sampling to miniaturize the equivalent circuit, then the circuit scale is reduced, but the processing accuracy deteriorates
Solution Approach 1:
The patent changes the sampling rate parameter to a fractional value that optimizes the balance between circuit scale and processing accuracy. By carefully selecting the sampling rate within the range of one to two times the symbol rate and配合 with the corrected initial tap coefficient determination method, the system achieves circuit miniaturization while maintaining processing accuracy through the compensated initialization approach
Data Source
AI summary
An adaptive equalizer includes a sample buffer that temporarily stores data obtained by fractional sampling at a sampling rate that is larger than one time and smaller than two times a symbol rate; and a processor coupled to the sample buffer and configured to: specify position of a training sequence in the data based on a correlation value between a first set of (f×T) samples and a second set of (f×T) samples following the first set of samples, assuming that the sampling rate is f, and a symbol length of a code pattern included in the training sequence inserted in the data is T, and calculate an initial value of a tap coefficient set to a tap of an adaptive equalization filter based on the specified training sequence, wherein the symbol length is set to be changeable so that f×T is an integer.