Adaptive Equalization Filter Tap Segmentation for Power Reduction
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Solution Overview
Problem
Conventional signal processing devices for PON systems require a large number of taps in finite impulse response (FIR) filters to achieve waveform distortion compensation for both polarizations, leading to increased power consumption, which is a limitation in power-constrained systems.
Innovation Solution
The adaptive equalization filter employs a configuration with one-tap FIR filters for the first to fourth filters and fewer than 46 taps for the fifth and sixth filters, using a constant modulus algorithm to update filter coefficients, reducing the total number of taps and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FIR filters with many taps are used for waveform distortion compensation in both polarizations, then compensation performance is improved, but power consumption increases
Solution Approach 1:
The patent segments the waveform distortion compensation function into two distinct parts: (1) polarization separation using 1-tap FIR filters for each polarization component, and (2) chromatic dispersion compensation using a separate filter with fewer taps applied to the combined signal. This segmentation allows each filter to be optimized for its specific function, reducing the total number of taps needed compared to applying full compensation filters to each polarization independently.
Solution Approach 2:
The patent merges the compensation operations by applying the chromatic dispersion compensation filter to the combined signal after polarization separation, rather than applying separate compensation filters to each polarization. This merging reduces redundancy in the filtering operations and decreases the total computational load and power consumption.
2Measurement precision
If FIR filters with many taps are used for waveform distortion compensation, then compensation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the compensation function into polarization separation (1-tap filters) and chromatic dispersion compensation (fewer-tap filter on combined signal), reducing the overall filter complexity while maintaining accuracy through functional specialization.
Solution Approach 2:
The patent extracts the chromatic dispersion compensation function from the polarization-specific processing path and applies it separately to the combined signal, removing redundant filtering operations and simplifying the overall device structure.
Data Source
Figure 1~2
Figure 3A~4B
Figure 5
AI summary
Each of a first filter (11) to a fourth filter (14) is an FIR filter having one tap. Each of a fifth filter (15) and a sixth filter (16) is an FIR filter having less than 46 taps. As a result, it is possible to obtain an adaptive equalization filter having a smaller total number of taps than an adaptive equalization filter using an FIR filter having 24 taps as each of the first to fourth filters.