LDPC Puncturing Pattern for Flexible Codeword Length Decoding
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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, particularly in supporting various data rates required in communication systems, and storing separate parity-check matrices for each codeword length reduces memory efficiency.
Innovation Solution
A method and apparatus that use shortening or puncturing techniques to generate LDPC codes with different codeword lengths from a given LDPC code, optimizing performance by applying a puncturing pattern that maximally suppresses irregularity in reliability during decoding, thereby supporting various codeword lengths without the need for additional storage or new parity-check matrices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate parity-check matrices are stored for each codeword length, then decoding performance is maintained, but memory efficiency deteriorates
Solution Approach 1:
The patent applies universality by designing a single parity-check matrix that can serve multiple codeword lengths through puncturing operations. The base matrix with dimensions supporting the maximum codeword length can generate all shorter codeword lengths by selectively puncturing columns, eliminating the need to store separate matrices for each length while maintaining decoding performance.
Solution Approach 2:
The patent utilizes parameter changes by varying the puncturing pattern and position based on the desired codeword length. By changing which columns are punctured from the base matrix, the system adapts to different codeword lengths without changing the fundamental matrix structure, thus maintaining reliability while reducing memory requirements.
2Ease of manufacture
If LDPC codes are limited to two fixed codeword lengths, then implementation is simplified, but adaptability deteriorates
Solution Approach 1:
The patent applies dynamics by making the code rate and codeword length adjustable through selective puncturing of the base LDPC code. The system starts with a base code at a first code rate and can dynamically puncture specific columns to achieve different code rates and codeword lengths, enabling adaptation to various data rates while maintaining a unified implementation framework.
Solution Approach 2:
The patent uses segmentation by dividing the base parity-check matrix into column groups that can be selectively punctured. This segmentation allows the system to maintain the overall structure of the base matrix for simplified implementation while enabling flexible configuration of different codeword lengths by selecting which segments (columns) to retain or remove.
3Adaptability or versatility
If puncturing is applied to generate shorter codewords, then flexibility improves, but decoding performance irregularity worsens
Solution Approach 1:
The patent applies local quality by carefully selecting which specific columns to puncture based on their position and connection patterns in the Tanner graph. Rather than random or uniform puncturing, the method identifies and preserves critical columns that maintain good decoding performance while removing others, thus achieving flexibility without sacrificing performance stability.
Solution Approach 2:
The patent utilizes feedback by analyzing the impact of puncturing on decoding performance and adjusting the puncturing pattern accordingly. The system evaluates how puncturing affects the Tanner graph structure and decoding convergence, using this information to optimize which columns should be punctured to maintain performance while achieving the desired codeword length flexibility.
Data Source
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AI summary
A method and an apparatus for channel decoding using a Low-Density Parity-Check (LDPC) code, the method comprising: demodulating a signal transmitted from a transmitter; determining position information of the punctured parity bits by estimating information about a predetermined order of parity bit sets to be punctured and the number of parity bit sets ; and decoding data using the position information of the punctured parity bits, wherein determining position of punctured parity bits comprises, determining a number of parity bits to be punctured; and determining a number of parity bit sets to be punctured based on the determined number of parity bits to be punctured; and acquiring a predetermined order of parity bit sets, wherein the predetermined order of parity bit sets is determined as 6, 4, 18, 9, 13, 8, 15, 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7, 11.