LDPC Lifting Scheme for Rate-Adaptive Child PCM Generation
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Solution Overview
Problem
Existing Low-Density-Parity-Check (LDPC) coding systems, particularly quasi-cyclic (QC) LDPC, require significant hardware resources for encoding and decoding, and struggle with efficient adaptation to varying information lengths and coding rates, leading to resource-intensive storage and processing needs.
Innovation Solution
The method involves lifting procedures to derive child parity check matrices (PCMs) from base PCMs using circulant sizes, lifting functions, and shifts, allowing for adaptive encoding and decoding by switching between different labeled PCMs based on changing coding rates and information lengths, thereby reducing resource consumption and optimizing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quasi-cyclic LDPC coding is used to achieve reliable data transmission, then error correction capability is improved, but hardware resource consumption increases
Solution Approach 1:
The patent implements a universal base PCM that can generate multiple child PCMs through different lifting functions, allowing a single hardware structure to support multiple coding rates and information lengths. The base PCM serves multiple functions by adapting to different communication requirements through parameter variation rather than requiring separate hardware for each coding scenario.
Solution Approach 2:
The patent changes parameters such as lifting size, lifting function, and circulant size to generate different child PCMs from a single base PCM. By varying these parameters, the system adapts to different coding rates and information lengths without changing the fundamental hardware structure, thus maintaining reliability while reducing device complexity.
2Adaptability or versatility
If multiple coding schemes are stored to support varying information lengths and coding rates, then adaptability is improved, but storage requirements increase
Solution Approach 1:
The patent segments the coding scheme into a compact base PCM and a set of lifting functions. Instead of storing complete PCMs for each coding rate and information length, the system stores only the essential base structure and generates specific PCMs on-demand by applying appropriate lifting functions with specific parameters, dramatically reducing storage requirements while maintaining full adaptability.
Solution Approach 2:
The patent creates child PCMs as derived copies from the base PCM through systematic transformations using lifting functions. Rather than storing independent copies of each PCM variant, the system generates them computationally from the single base PCM, reducing storage needs from O(N×M) to O(N) where N is the base PCM size and M is the number of variants.
3Reliability
If lifting procedures with multiple combinations of circulant size, lifting function, and base PCM are used, then coding performance is improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary optimization by pre-selecting the best combination of circulant size, lifting function, and base PCM for each information length and coding rate pair, storing these optimal selections in lookup tables. During actual operation, the system only needs to retrieve and apply the pre-determined optimal parameters rather than evaluating multiple combinations in real-time, significantly reducing calculation complexity while maintaining optimal coding performance.
Data Source
AI summary
A method for generating a code, a method for encoding and decoding data, and an encoder and a decoder performing the encoding and decoding are disclosed. In an embodiment, a method for lifting a child code from a base code for encoding and decoding data includes determining a single combination of a circulant size, a lifting function, and a labelled base matrix PCM according to an information length and a code rate using data stored in a lifting table. The lifting table was defined at a code generation stage. The method also includes calculating a plurality of shifts for the child code. Each shift is calculated by applying the lifting function to the labelled base matrix PCM with a defined index using the circulant size and using the derived child PCM to encode or decode data.