Linear Block Code Decoding With Corrupt Symbol Erasure
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Solution Overview
Problem
The upstream path in two-way hybrid fiber coaxial cable systems faces significant impairments due to burst noise and lack of continuous calibrated signal sources, leading to frequent alignment problems and difficulty in determining ingress points, especially with transient noise, which affects signal-to-noise ratio and error correction capabilities.
Innovation Solution
A receiver and communication system that employs a comparator to identify corrupt data symbols by comparing them with predetermined limits, generating control signals to mark and erase these symbols before error correction, thereby increasing error correction capabilities using linear block codes and demodulation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction decoding is performed without identifying corrupt data symbols, then the decoding process is simpler and faster, but the error correction capability is limited and cannot effectively handle burst noise
Solution Approach 1:
The patent applies preliminary action by comparing data symbols with predetermined limits (saturation and threshold limits) before the decoding process. This pre-identification of corrupt symbols allows the decoder to know in advance which symbols are corrupted, enabling it to focus correction efforts on these specific symbols rather than attempting to correct all symbols uniformly. This preliminary identification step significantly enhances error correction capability while keeping the decoder itself relatively simple.
Solution Approach 2:
The patent introduces an intermediary component (the comparator circuit) that sits between the receiver and the decoder. This intermediary identifies corrupt data symbols by comparing them with predetermined limits and provides this information to the decoder. The decoder then uses this information to enhance its correction capability. This intermediary approach allows the system to achieve high error correction performance without making the decoder itself overly complex.
2Measurement precision
If the system uses predetermined limits to identify corrupt data symbols, then burst noise and other impairments can be detected, but the system requires additional comparison operations that increase processing complexity
Solution Approach 1:
The patent uses parameter changes by establishing predetermined saturation limits and threshold limits for data symbols. These limits are set based on the expected range of valid symbol values. By comparing received symbols against these predetermined parameter thresholds, the system can accurately identify corrupt symbols without requiring complex analysis. The simplicity of the comparison operation keeps the comparator circuit relatively simple while maintaining high detection accuracy.
3Reliability
If error correction is performed on all data symbols uniformly, then the decoding process is straightforward, but the correction capability is insufficient for handling burst noise and transient impairments
Solution Approach 1:
The patent applies local quality by treating different data symbols differently based on their corruption status. Instead of applying uniform error correction to all symbols, the system first identifies which specific symbols are corrupt using the comparator circuit and predetermined limits. The decoder then focuses its correction efforts locally on only those identified corrupt symbols. This selective approach significantly improves reliability for handling burst noise while maintaining decoding efficiency by avoiding unnecessary processing of clean symbols.
Data Source
AI summary
Disclosed is an apparatus and method for increasing the error correction capabilities of a receiver circuit that receives a data stream of encoded data symbols that are encoded with a linear block code. Analog and digital comparator circuits are used to detect laser clipping or analog to digital converter overloading. Corrupted symbols are detected by comparing in-phase and/or quadrature phase baseband signals with pre-determined threshold limits that indicate that the in-phase and quadrature phase signals have exceeded the normal signal trajectory of an unimpaired signal. Corrupted symbols may also be detected by determining that the laser has been clipped. Corrupted symbols are marked for erasure prior to decoding and error correction. Erasure of corrupted signals increases the error correction capabilities of the decoder circuit.