Echo Cancellation via Segmented FIR Filter Window Shifting
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Solution Overview
Problem
High-speed serial communication channels with long impulse responses require complex and power-consuming echo cancellation, especially in automotive and industrial applications, due to the large number of FIR filter taps needed, which increases complexity and power consumption.
Innovation Solution
The technique divides the echo response into segments, estimates and cancels echoes in each segment, and updates coefficients using the least mean squares algorithm, reducing the number of echo taps required while maintaining performance by reusing limited taps and shifting the FIR filter window once coefficients reach steady state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of FIR filter taps is increased to cover the full echo response, then echo cancellation performance is improved, but device complexity and power consumption increase significantly
Solution Approach 1:
The patent divides the full echo response into multiple segments and processes each segment separately with a limited number of FIR filter taps. Instead of using a large number of taps to cover the entire echo response, the system uses segmentation to break down the complex echo cancellation task into smaller, more manageable segments, each handled by a reduced tap filter.
Solution Approach 2:
The patent employs periodic action by repeatedly updating filter coefficients for different segments in a cyclic manner. The system processes one segment, updates coefficients, then moves to the next segment, and repeats this periodic process across all segments. This allows the use of fewer taps per segment while still achieving comprehensive echo cancellation through repeated periodic updates.
2Reliability
If the number of FIR filter taps is increased to cover the full echo response, then echo cancellation performance is improved, but power consumption increases significantly
Solution Approach 1:
By segmenting the echo response and using reduced tap filters for each segment, the computational load per processing cycle is significantly reduced, leading to lower power consumption. The system processes smaller segments with fewer taps rather than handling the full echo response with a large tap filter continuously.
Solution Approach 2:
The periodic update approach allows the system to use fewer taps at any given moment while achieving comprehensive cancellation through repeated cycles. Power consumption is reduced because the full computational effort is distributed across multiple periodic updates rather than requiring simultaneous operation of all taps.
3Reliability
If adaptive cancellation is implemented to handle channel behavior changes, then echo cancellation effectiveness is improved, but the system becomes more complex
Solution Approach 1:
The patent applies segmentation to adaptive cancellation by dividing the channel into multiple segments and implementing adaptive filtering on each segment separately. This reduces the complexity of the adaptive algorithm compared to processing the entire channel response at once, while still maintaining effectiveness through segment-specific adaptation.
Solution Approach 2:
The system implements dynamic adaptation by continuously updating filter coefficients for each segment based on changing channel conditions. The adaptive nature allows the system to respond to channel behavior changes while the segmented approach keeps the computational complexity manageable through localized adaptation rather than global re-computation.
Data Source
AI summary
The disclosure relates to techniques for power efficient and smart echo cancellation. An apparatus is provided that comprises a finite impulse response filter having a set of M+1 filter coefficients for filtering values of a reference signal to obtain a first filtered reference signal. The apparatus comprises an interval selector for selecting values of the reference signal associated with a k-th time interval of an echo impulse response having N time intervals. The apparatus comprises M delay elements arranged after the interval selector for successively delaying the selected values. The apparatus comprises M+1 error estimators. A first error estimator is coupled to an output of the interval selector. Each of the remaining M error estimators is coupled to an output of a respective delay element. The M+1 error estimators are configured to determine the M+1 filter coefficients to minimize deviation between the first filtered reference signal and the received signal.