Phase Recovery Feedback Loop for Turbo Equalization Signals
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Solution Overview
Problem
The existing turbo iteration method in communications systems is limited in improving input signal quality, leading to restricted performance enhancement due to cycle skipping and degraded signal quality, especially in bandwidth-limited systems with intersymbol interference.
Innovation Solution
A signal processing system and method that includes a phase recovery apparatus, a post filtering apparatus, and an information iteration apparatus, where the phase recovery apparatus performs phase recovery based on feedback signals from the information iteration apparatus, and the information iteration apparatus performs sequence detection and error detection in a soft value information iteration manner to improve signal quality, with the feedback signal used to enhance phase recovery precision and reduce cycle skipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a finite impulse response filter is used to compress signal bandwidth through pre-shaping, then spectrum effectiveness is improved, but intersymbol interference is caused degrading system performance
Solution Approach 1:
The patent applies preliminary action by performing pre-shaping filtering before signal transmission to compress bandwidth, and then applying post-filtering and sequence detection after reception to mitigate the resulting intersymbol interference. This proactive approach addresses the bandwidth compression issue before it fully degrades the signal, allowing spectrum effectiveness improvement while preparing countermeasures for the inevitable ISI.
Solution Approach 2:
The patent implements feedback through turbo iteration between the sequence detector and forward error correction decoder. The soft value information exchanged in iterative manner allows the system to refine signal estimates and correct errors progressively, compensating for the performance degradation caused by bandwidth compression and intersymbol interference.
2Ease of operation
If phase recovery is performed on degraded received signal, then signal processing is completed, but cycle skipping is frequently caused generating incorrect signal
Solution Approach 1:
The patent uses feedback through turbo iteration where soft value information from the sequence detector and forward error correction decoder are exchanged iteratively. This feedback mechanism allows the system to refine phase estimates and correct signaling errors progressively, preventing cycle skipping from propagating and ensuring signal correctness even when initial phase recovery is imperfect.
Solution Approach 2:
The patent applies beforehand cushioning by implementing post-filtering before sequence detection and using iterative turbo decoding to cushion against the effects of cycle skipping. The forward error correction code provides a safety margin that protects against incorrect signal generation, allowing the system to tolerate phase recovery errors without catastrophic failure.
3Measurement precision
If turbo iteration is performed between sequence detector and FEC, then error detection is improved, but input signal quality of post filter cannot be improved greatly limiting compensation capability
Solution Approach 1:
The patent extends the feedback mechanism to include not only iteration between sequence detector and FEC but also incorporates the output of the post-filter into the iterative process. By using soft value information from multiple sources and iterating among sequence detector, FEC decoder, and phase recovery, the system can improve input signal quality for the post-filter while maintaining high error detection accuracy.
Solution Approach 2:
The patent merges multiple signal processing functions into a unified iterative framework. The sequence detector, FEC decoder, phase recovery, and post-filter are combined and iteratively processed together, allowing information to flow between all components. This merging enables simultaneous improvement of both error detection accuracy and input signal quality, as each component benefits from refined outputs of others in the iteration loop.
Data Source
AI summary
A signal processing system and method, and an apparatus are provided. A phase recovery apparatus may be used to: receive a feedback signal fed back by an information iteration apparatus, perform, based on the feedback signal, phase recovery on a signal output by an equalizer, and output a phase-recovered signal to a post filtering apparatus, so that the post filtering apparatus performs noise filtering on the phase-recovered signal, and outputs a noise-filtered signal to the information iteration apparatus. To be specific, the phase recovery may be performed, based on the signal fed back by the information iteration apparatus, on the signal output by the equalizer. Because output of the information iteration apparatus is more accurate in determining the signal, precision of the phase recovery can be improved, cycle skipping is reduced, and input signal quality of the post filtering apparatus is improved.