LDPC Puncturing Pattern for Flexible Codeword Lengths
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Solution Overview
Problem
Current LDPC code systems, such as DVB-S2, are limited to only two codeword lengths, which restricts their extendibility and flexibility, and require separate parity-check matrices for each length, leading to inefficient memory usage and the need for various codeword lengths to support different data rates in communication systems.
Innovation Solution
The method employs puncturing and shortening techniques to generate LDPC codes with different codeword lengths from a given parity-check matrix, using a puncturing pattern that maximally suppresses irregularity in reliability during decoding, allowing for efficient support of various codeword lengths without additional storage for each length, and optimizing performance for DVB-S2 architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate parity-check matrices are stored for each codeword length, then decoding accuracy is maintained, but memory usage increases and system flexibility decreases
Solution Approach 1:
The patent applies universality by designing a single base parity-check matrix that can serve multiple codeword lengths through systematic puncturing and shortening. The base matrix is constructed with a specific structure that allows it to generate various code rates and lengths by selectively removing columns (puncturing) or setting information bits to zero (shortening), eliminating the need to store separate matrices for each codeword length while maintaining decoding performance
Solution Approach 2:
The patent segments the base parity-check matrix into functional blocks that can be independently manipulated. The matrix is designed with modular structures where specific column groups can be punctured or shortened based on the desired codeword length, allowing flexible adaptation while preserving the overall decoding capability through the structured approach
2Adaptability or versatility
If puncturing is applied to generate different codeword lengths, then system extendibility improves, but decoding performance may deteriorate due to irregular reliability
Solution Approach 1:
The patent applies local quality by implementing structured puncturing patterns that selectively remove specific columns from the base parity-check matrix based on their importance and position. Rather than random puncturing, the method identifies and preserves critical columns that maintain decoding performance while removing less critical ones, creating a non-uniform but optimized puncturing pattern that adapts to the specific codeword length requirements
Solution Approach 2:
The patent applies preliminary action by pre-designing the base parity-check matrix with a specific structure that anticipates future puncturing and shortening operations. The matrix is constructed in advance with embedded redundancy and structured patterns that ensure optimal performance across multiple target codeword lengths, allowing the system to extend to different lengths without redesigning the entire code structure
3Adaptability or versatility
If multiple parity-check matrices are used to support various data rates, then adaptability to different data rates improves, but device complexity and memory requirements increase
Solution Approach 1:
The patent applies universality by creating a single base parity-check matrix that can generate multiple code rates and codeword lengths through systematic puncturing and shortening operations. This universal matrix replaces the need to store multiple separate parity-check matrices, significantly reducing memory requirements while maintaining the ability to support various data rates through algorithmic transformation of the base matrix
Solution Approach 2:
The patent applies parameter changes by modifying the effective code rate and codeword length parameters through selective puncturing and shortening of the base matrix. By changing which columns are retained or removed, and which information bits are set to zero, the system dynamically adjusts code parameters to match different data rate requirements without changing the fundamental matrix structure or requiring additional storage
Data Source
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AI summary
An apparatus and a method for channel encoding using a Low-Density Parity-Check (LDPC) code, the method comprising: determining a number of parity bits for puncturing; determining a number of parity bit sets based on the number of parity bits for puncturing, each of the parity bit sets being formed by parity bits at a predetermined interval; and puncturing parity bits based on the number of parity bit sets and a predetermined order of parity bit sets to be punctured, wherein the predetermined order of parity bit sets is determined as 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 4, 2, 26, 16, 34,19,10,12,23,1,6,30,15.