LDPC Channel Decoding with Shortening Patterns for Flexible Code 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, particularly in supporting various data rates required for adaptive communication systems and broadcast services, and storing separate parity-check matrices for each codeword length reduces memory efficiency.
Innovation Solution
The method involves using shortening and puncturing techniques to generate LDPC codes with different codeword lengths from a given LDPC code, specifically by grouping columns in a parity-check matrix, determining a shortening range, and applying a predetermined shortening pattern to achieve the desired codeword length, thereby supporting various codeword lengths without the need for additional storage or new parity-check matrices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate parity-check matrices are stored for each codeword length, then code versatility is improved, 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 column selection. The matrix is constructed with columns that can be selectively included or excluded based on the desired codeword length, allowing one matrix to fulfill multiple coding functions that would traditionally require separate matrices for each length.
2Device complexity
If LDPC codes are limited to two fixed codeword lengths, then implementation complexity is reduced, but system flexibility deteriorates
Solution Approach 1:
The patent implements dynamics by enabling the system to adaptively select different column subsets from the parity-check matrix based on the required codeword length. This dynamic column selection mechanism allows the system to flexibly adjust between different code lengths without requiring separate pre-configured matrices for each length, thus maintaining simplicity while gaining adaptability.
3Quantity of substance
If a single parity-check matrix is used for multiple codeword lengths, then memory efficiency is improved, but code design complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the parity-check matrix into columns that can be independently selected based on the desired codeword length. The matrix is designed with a structured column arrangement where specific columns correspond to different length requirements, allowing the system to segment the matrix into appropriate subsets without requiring complex redesign for each length.
Data Source
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AI summary
A method for channel decoding in a communication system using a DVB-S2 Low-Density Parity-Check (LDPC) code, the method comprising demodulating a signal transmitted from a transmitter; determining a position of a shortened bit by estimating information on a shortening pattern of an LDPC code from the demodulated signal; and decoding data using the determined position of the shortened information bit wherein the information on a shortening pattern comprises a predetermined shortening pattern defined in a given table.