QC-LDPC Bit Mapping with Cyclic Block Permutation for QAM
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Solution Overview
Problem
Existing bit-interleaved coding and modulation (BICM) systems using quasi-cyclic low-density parity-check codes (QC LDPC codes) and quadrature amplitude modulation (QAM) face challenges in optimizing cyclic block permutations to achieve optimal performance for both blind demapping and iterative demapping, leading to suboptimal communication performance due to the complexity of matching importance levels of cyclic blocks with constellation robustness levels.
Innovation Solution
The implementation of a method to optimize cyclic block permutations using Monte-Carlo simulations and constrained random permutations to determine optimal cyclic block permutations that achieve low signal-to-noise ratio (SNR) for blind demapping, while maintaining performance for iterative demapping, and selecting non-uniform constellations that match the importance levels of cyclic blocks with constellation robustness levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bit-interleaved coding and modulation systems use standard cyclic block permutations, then the system structure remains simple, but communication performance is suboptimal due to inability to match cyclic block importance levels with constellation robustness levels
Solution Approach 1:
The patent applies parameter changes by systematically varying cyclic block permutations to match different importance levels of cyclic blocks with corresponding robustness levels of constellation bits. This optimization of permutation parameters enables the system to achieve optimal communication performance for both blind demapping and iterative demapping scenarios.
2Reliability
If optimized cyclic block permutations are implemented to achieve optimal performance for blind demapping, then bit error rates are reduced, but the system complexity increases due to the need for Monte-Carlo simulations and performance evaluation
Solution Approach 1:
The patent applies preliminary action by pre-determining optimal cyclic block permutations through Monte-Carlo simulations and performance evaluations. These optimized permutations are stored and directly applied during actual communication operations, eliminating the need for real-time optimization and reducing operational complexity.
Solution Approach 2:
The system performs self-service by automatically evaluating different cyclic block permutations using Monte-Carlo simulations to determine which permutations yield the lowest bit error rates. This self-optimization capability allows the system to identify and implement the best permutation strategy without external intervention.
3Reliability
If standard constellation mappings are used, then the mapping process is straightforward, but transmission reliability is suboptimal due to mismatch between cyclic block importance levels and constellation bit robustness levels
Solution Approach 1:
The patent applies local quality by creating non-uniform constellations where different constellation bits have different robustness levels that are specifically matched to the importance levels of different cyclic blocks. This localized optimization ensures that more important cyclic blocks are mapped to more robust constellation bits, thereby improving overall transmission reliability.
Data Source
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AI summary
A communication method according to an aspect of the present disclosure includes executing a cyclic block permutation for a codeword generated based on a quasi-cyclic parity-check code including a repeat-accumulate quasi-cyclic low-density parity-check code, where the cyclic block permutation is permutation of cyclic blocks within the codeword, and mapping each bit of the codeword for which the cyclic block permutation is executed to a constellation point of a non-uniform constellation. This improves receiving performance.