Adaptive LDPC Parity Matrix Selection for Noise-Erasure Decoding
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Solution Overview
Problem
LDPC decoding performance degrades due to combinations of bit eliminations caused by external noise in wireless and PLC systems, particularly when eliminated bits form stopping sets, leading to increased bit error rates and reduced throughput.
Innovation Solution
The system dynamically changes the LDPC encoding method by selecting a different parity check matrix based on estimated candidate elimination bits, ensuring that the combination of eliminated bits does not form a stopping set, thereby improving decoding performance without altering the code length or code rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If bit elimination is performed to handle external noise influence, then noise resistance is improved, but decoding performance deteriorates when eliminated bits form stopping sets
Solution Approach 1:
The patent applies preliminary action by estimating candidate elimination bits before actual decoding occurs. The transmission device predicts which bits will be eliminated due to external noise and pre-adjusts the parity check matrix to prevent stopping set formation. This advance preparation ensures that when bits are eliminated during reception, the decoder can still successfully recover the transmitted data without performance degradation.
Solution Approach 2:
The patent implements feedback by using estimated elimination bit information to dynamically adjust the encoding strategy. The transmission device receives feedback about noise conditions, estimates which bits will be eliminated, and modifies the parity check matrix selection accordingly. This closed-loop approach allows the system to adapt its encoding to the actual noise environment, maintaining decoding performance while preserving noise resistance.
2Device complexity
If a fixed parity check matrix is used for LDPC encoding, then device complexity is reduced, but adaptability to different noise conditions deteriorates
Solution Approach 1:
The patent applies dynamics by making the parity check matrix selection adaptive rather than fixed. The system dynamically chooses from multiple pre-defined parity check matrices based on estimated noise conditions and candidate elimination bit patterns. This dynamic adaptation allows the encoding scheme to respond to varying noise environments while maintaining relatively simple operation, as the selection is based on predetermined matrix options rather than complex real-time generation.
Solution Approach 2:
The patent implements parameter changes by varying which parity check matrix is used for encoding based on noise conditions. Instead of changing the fundamental encoding structure, the system adjusts the specific matrix parameters (selection from predefined options) to match the current noise environment. This approach maintains encoding simplicity while achieving adaptability, as the change involves selecting from a finite set of predetermined matrices rather than generating new matrices dynamically.
Data Source
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AI summary
In a transmission device, a determining unit determines, for use in transmission, an LDPC encoding method corresponding to occurrence conditions of external noise from a plurality of LDPC encoding methods each having the same code length and the same code rate and being defined by a different parity check matrix, and an encoding unit generates a codeword bit sequence by encoding transmission data using the LDPC encoding method determined by the determining unit.