LDPC Decoder Noise Injection for Trapping Set Escape
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Solution Overview
Problem
Low Density Parity Check (LDPC) decoders face error floors in frame error rate (FER) performance due to trapping sets, which traditional methods struggle to overcome, especially in communication systems requiring lower error floors than current standards allow.
Innovation Solution
The implementation of Stochastic Floor Mitigation (SFM) in LDPC decoders, which involves adding noise strategically during decoding through a noise generation circuit and trapping set detection, enables the decoder to escape trapping sets and improve error floor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LDPC decoding methods are used, then the decoder operates with standard complexity, but the error floor performance deteriorates due to trapping sets
Solution Approach 1:
A stochastic floor mitigation (SFM) circuit is introduced as an intermediary component between the check node processor and the output. This circuit includes a noise generator that adds controlled stochastic noise to the check node outputs, enabling the decoder to escape trapping sets and improve error floor performance without fundamentally redesigning the entire decoding architecture
Solution Approach 2:
The invention changes the parameter of check node output values by adding stochastic noise. The noise generator modifies the magnitude and sign of check node outputs dynamically, transforming the deterministic decoding process into a stochastic one that can escape local minima (trapping sets) and achieve better error floor performance
2Reliability
If more iterations are performed to reduce errors, then error floor performance improves slightly, but decoding time and complexity increase significantly
Solution Approach 1:
Instead of performing many iterations with standard decoding, the invention applies partial action by introducing stochastic noise only at critical points (when trapping sets are encountered). The SFM circuit activates noise injection selectively rather than continuously, achieving error floor improvement without proportionally increasing decoding time
3Reliability
If custom-built changes are made to address specific trapping sets, then those particular trapping sets are resolved, but the solution becomes expensive and difficult to implement
Solution Approach 1:
The SFM circuit provides a universal solution that addresses all trapping sets simultaneously rather than requiring custom modifications for each specific trapping set. The noise generator applies stochastic perturbations that can escape any trapping set, making the solution broadly applicable without complex customizations
Solution Approach 2:
The decoder system serves itself by automatically detecting trapping set conditions and activating the SFM circuit when needed. The system monitors its own performance and applies stochastic floor mitigation autonomously without requiring external intervention or complex control logic
Data Source
AI summary
A method and apparatus as described herein provide a novel modification to any iterative FEC decoder method that can improve FER performance in the error floor region. Many iterative FEC methods, such as commonly used LDPC decoders, have error floors where the performance of the decoder does not improve below a certain threshold. Error Floors are caused by trapping sets from which traditional methods cannot escape. With Stochastic Floor Mitigation, according to embodiments of the present disclosure, noise is strategically added to the operations occurring during decoding resulting in significantly improved error floor performance.