Single-Stage FDEQ Structure for Impairment Compensation
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Solution Overview
Problem
Conventional frequency-domain equalization (FDEQ) systems require complex hardware and high power consumption due to the need for multiple stages and large numbers of multipliers to compensate for both non-time-varying and time-varying impairments in communication channels.
Innovation Solution
A single-stage FDEQ structure that combines data preprocessing and adaptive equalization using a 2×2 multiple-input multiple-output (MIMO) processor, with initial MIMO taps set to compensate non-time-varying fixed impairments and updated using gradient constraints to address both impairment types, reducing hardware complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional two-stage FDEQ is used to compensate for both non-time-varying and time-varying impairments, then compensation performance is improved, but hardware complexity and power consumption increase due to large numbers of multipliers
Solution Approach 1:
The patent merges the fixed equalizer and adaptive equalizer into a single unified FDEQ stage. The single-stage structure processes both non-time-varying (chromatic dispersion, S21) and time-varying (PMD, SOP tracking) impairments together in one frequency-domain processing block, eliminating the need for separate processing stages and reducing the overall number of multipliers required.
Solution Approach 2:
The single-stage FDEQ structure is designed to perform multiple equalization functions simultaneously. It compensates for both fixed impairments (chromatic dispersion, S21, match filtering) and adaptive impairments (PMD, SOP tracking, polarization division de-multiplexing) within a single processing framework, making the system more versatile while reducing complexity.
2Reliability
If conventional two-stage FDEQ is used to compensate for both non-time-varying and time-varying impairments, then compensation performance is improved, but power consumption increases due to large numbers of multipliers
Solution Approach 1:
The patent merges the fixed equalizer and adaptive equalizer into a single unified FDEQ stage. The single-stage structure processes both non-time-varying (chromatic dispersion, S21) and time-varying (PMD, SOP tracking) impairments together in one frequency-domain processing block, eliminating the need for separate processing stages and reducing the overall number of multipliers required.
3Adaptability or versatility
If time-domain equalization is used to compensate for impairments, then adaptability is improved, but digital signal processing complexity increases significantly with large number of taps
Solution Approach 1:
The patent replaces time-domain equalization with frequency-domain equalization. By transforming the equalization process from time-domain to frequency-domain using FFT, the system achieves the same adaptive impairment compensation with significantly reduced computational complexity. The frequency-domain approach requires fewer operations per symbol, especially when using a large number of taps.
Data Source
AI summary
The disclosed systems, structures, and methods are directed to a single-stage frequency-domain equalization (FDEQ) structure implemented on a processor, comprising a data preprocessing unit configured to concatenate received data samples in time-domain digital signals, transform the concatenated data samples in the time-domain digital signals to frequency-domain digital signals, and an adaptive equalizer comprising 2×2 multiple-input multiple output (MIMO) configured to compensate for non-time-varying fixed impairments and time-varying adaptive impairments in the frequency-domain digital signals.