Adaptive LDPC Encoding for External Noise and Stopping Sets
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Solution Overview
Problem
Decoding performance in wireless and PLC systems degrades due to combinations of eliminated bits influenced by external noise, particularly when these combinations form stopping sets, leading to increased bit error rates and reduced throughput.
Innovation Solution
A transmission device and method that dynamically select an LDPC encoding method based on external noise conditions, using different parity check matrices to avoid combinations of codeword bits that form stopping sets, thereby improving decoding performance without altering code length or rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed LDPC encoding method is used, then the device complexity is reduced, but the decoding performance degrades in external noise environments
Solution Approach 1:
The patent implements dynamic selection of LDPC encoding methods based on external noise conditions. The transmission device determines whether external noise is present and selects between a first LDPC encoding method (for no external noise) and a second LDPC encoding method (for external noise present), allowing the system to adapt its encoding strategy to current channel conditions rather than using a fixed encoding method.
Solution Approach 2:
The patent changes the parameters of the LDPC encoding method by selecting different parity check matrices based on external noise conditions. When external noise is detected, the system switches to a second LDPC encoding method with a specifically designed parity check matrix that avoids stopping sets containing eliminated bits, thereby changing the structural parameters of the encoding method to match the noise environment.
2Object-affected harmful factors
If bits influenced by external noise are eliminated, then the impact of external noise is reduced, but decoding performance degrades when eliminated bits form stopping sets
Solution Approach 1:
The patent applies preliminary anti-action by designing the second LDPC encoding method's parity check matrix in advance to prevent the formation of stopping sets containing eliminated bits. Rather than reacting to stopping sets after elimination occurs, the system proactively configures the encoding method so that the parity check matrix structure inherently avoids creating stopping sets with the positions of bits that are likely to be eliminated due to external noise.
Solution Approach 2:
The patent enables the decoder to skip the problematic stopping set issue by using a parity check matrix that bypasses the formation of stopping sets containing eliminated bits. This allows the decoding process to rush through the challenging external noise condition without getting stuck in the stopping set problem that would otherwise cause decoding failure.
3Reliability
If the parity check matrix is changed to avoid stopping sets, then decoding performance is improved, but the adaptability to different noise conditions requires multiple encoding methods
Solution Approach 1:
The patent segments the LDPC encoding methods into different types based on external noise conditions. It defines a first LDPC encoding method for environments without external noise and a second LDPC encoding method for environments with external noise, allowing the system to divide the encoding strategy into specialized segments that optimize performance for specific noise conditions rather than using a single general-purpose method.
Data Source
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.