QC LDPC Cyclic Block Permutation for Non-Uniform QAM Mapping
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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 and non-uniform constellations for different code rates, leading to suboptimal communication performance.
Innovation Solution
The proposed solution involves executing a cyclic block permutation for codewords generated based on QC LDPC codes, mapping bits to non-uniform constellations, and selecting the permutation and constellation based on the code rate, specifically defining permutations and constellations for code rates 6/15, 7/15, and 8/15 to improve communication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bit interleavers are used in BICM systems with QC LDPC codes, then the system can transmit data, but communication performance is suboptimal due to lack of optimization for different code rates
Solution Approach 1:
The patent implements dynamic selection of cyclic block permutation patterns based on code rate. Different permutation patterns (first pattern for code rate 1/3, second pattern for other code rates) are defined and selected according to the actual code rate being used, allowing the system to adapt its interleaving strategy to match the specific code rate requirements and achieve optimal communication performance
Solution Approach 2:
The patent changes the parameters of the cyclic block permutation based on code rate. By defining different permutation patterns corresponding to different code rates, the system optimizes the interleaving parameters to match the code rate characteristics, thereby improving bit error rate performance without requiring complex adaptive algorithms
2Measurement precision
If cyclic block permutation is optimized for different code rates, then bit error rates improve, but the system requires multiple permutation patterns increasing complexity
Solution Approach 1:
The patent segments the permutation patterns into distinct types based on code rate requirements. By dividing the permutation patterns into a first pattern for code rate 1/3 and a second pattern for other code rates, the system provides optimized performance for each segment while keeping the overall structure manageable and implementable
Solution Approach 2:
The patent creates a universal cyclic block permutation mechanism that can handle multiple code rates through pattern selection. The same cyclic block permutation operation serves multiple functions by selecting appropriate patterns based on code rate, eliminating the need for completely different interleaving mechanisms for each code rate
Data Source
AI summary
A communication method 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 any one of constellation point of a non-uniform constellation.