Decision Feedback Equalization Using FFT-Based Tap Calculation
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Solution Overview
Problem
Conventional equalization technologies face challenges in efficiently addressing inter-symbol interferences (ISI) in high-speed digital communication, leading to unstable signal voltages and increased bit error rates due to their complexity and inefficiency in calculating tap coefficients for feed-forward and feedback equalizers.
Innovation Solution
A decision feedback equalization (DFE) processing device and method that utilize a channel estimator to calculate feed-forward and feedback tap coefficients using a conjugate gradient descent algorithm, with circulant matrix construction and fast Fourier transformation (FFT) to reduce computational complexity from O(N^3) to O(k×N×log 2(N)) for efficient equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional equalization technologies are used, then equalization function is provided, but computation complexity is high and performance is poor
Solution Approach 1:
The patent replaces conventional direct matrix inversion methods with a conjugate gradient descent algorithm that utilizes the circulant structure of the autocorrelation matrix. This substitution transforms a computationally intensive O(N³) operation into an efficient O(N log N) operation using FFT-based matrix-vector multiplication, significantly reducing computation complexity while maintaining equalization performance.
Solution Approach 2:
The patent changes the computational approach by exploiting the circulant structure parameter of the autocorrelation matrix. By recognizing and utilizing this specific mathematical structure, the algorithm transforms the problem from general matrix inversion to a specialized form that can be solved efficiently using FFT, thereby reducing computational complexity without sacrificing reliability.
2Speed
If signal speed is increased, then communication efficiency is improved, but inter symbol interference increases
Solution Approach 1:
The patent implements decision feedback equalization where the equalizer uses feedback from previously detected symbols to compensate for inter symbol interference. The feedback path allows the system to subtract the estimated interference from subsequent symbols, enabling higher signal speeds while maintaining signal integrity by actively canceling the harmful ISI effects.
Data Source
AI summary
The present application disclosed a decision feedback equalization processing device and method. The device comprises: a channel estimator for receiving an input signal, and determining, based on the input signal, an input signal autocorrelation matrix Ryy, an input-output signal cross-correlation matrix Ryx and an input-output signal cross-correlation vector ryx; a tap coefficient calculator for receiving Ryy, Ryx and ryx, and calculating a feed-forward equalizer (FFE) tap coefficient vector g and a feedback equalizer (FBE) tap coefficient vector f, wherein at least one of the FFE tap coefficient vector g and the FBE tap coefficient vector f is calculated using a conjugate gradient descent algorithm. The tap coefficient calculator comprises: a circulant matrix construction unit and a fast Fourier transformation (FFT) calculating unit. And the device further comprises a decision feedback equalizer for receiving from the tap coefficient calculator the FFE tap coefficient vector g and the FBE tap coefficient vector f, and performing equalization on the input signal and generating an equalized output signal.