QC-LDPC Bit Mapping with Cyclic Block Permutation Optimization
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Solution Overview
Problem
In bit-interleaved coding and modulation (BICM) systems using quasi-cyclic low-density parity-check codes (QC LDPC codes) and quadrature amplitude modulation (QAM), existing methods lack an efficient method to optimize cyclic block permutations for both blind demapping and iterative demapping, leading to suboptimal communication performance.
Innovation Solution
The implementation of a method to optimize cyclic block permutations by generating a large number of permutations randomly, using Monte-Carlo simulations to determine threshold SNR for blind demapping, and applying constraints to find permutations that achieve good performance for both blind and iterative demapping, while selecting optimal non-uniform constellations for different code rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing methods are used for cyclic block permutations, then implementation is simple, but communication performance is suboptimal
Solution Approach 1:
The patent applies preliminary action by pre-optimizing cyclic block permutations through Monte-Carlo simulations before actual communication operations. The method generates a large number of random permutations, evaluates their performance for both blind and iterative demapping, and selects optimal permutations in advance. This pre-computation approach resolves the contradiction by preparing optimal configurations beforehand, achieving high communication performance without requiring complex real-time optimization during operation.
2Reliability
If random permutations are generated and optimized using Monte-Carlo simulations, then communication performance improves, but computational complexity increases
Solution Approach 1:
The patent applies partial or excessive action by generating a large number of random permutations beyond what would be minimally necessary, then using Monte-Carlo simulations to evaluate and select the optimal subset. This approach intentionally performs more computations than strictly required to ensure finding the best permutations for both blind and iterative demapping scenarios. The excessive exploration in the optimization phase trades computational effort during setup for superior performance during actual communication.
Solution Approach 2:
The patent applies parameter changes by systematically varying permutation parameters and constellation parameters during the optimization process. The method changes different parameters (permutation patterns, constellation configurations) and evaluates their impact on communication performance through simulations. By exploring different parameter combinations and selecting optimal values, the patent achieves improved bit error rate performance while managing the complexity through structured parameter exploration.
3Adaptability or versatility
If optimizations are applied for both blind demapping and iterative demapping, then robustness across different demapping methods improves, but the difficulty of detecting and measuring optimal permutations increases
Solution Approach 1:
The patent applies universality by developing a permutation optimization method that simultaneously serves multiple demapping approaches (blind demapping and iterative demapping). The same optimized cyclic block permutations are designed to work effectively with both demapping methods, making the solution universally applicable. This multi-functional approach resolves the contradiction by creating a single set of permutations that adapts to different demapping scenarios, reducing the need for separate optimizations for each method.
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.