QC-LDPC Cyclic-Block Interleaving for Spatial Multiplexing
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Solution Overview
Problem
The reception performance of communication systems using bit-interleaved coding and modulation (BICM) with quasi-cyclic low-density parity-check (QC-LDPC) codes is not optimally mapped onto constellation words, particularly in spatial-multiplexing blocks, leading to suboptimal performance.
Innovation Solution
An interleaving method that permutes the cyclic blocks of a QC-LDPC codeword to generate constellation words for spatial-multiplexing blocks, ensuring that bits from different cyclic blocks are mapped to constellation words based on their importance and robustness levels, improving the mapping efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mapping methods are used for QC-LDPC codeword bits onto constellation words, then the system structure remains simple, but the reception performance is suboptimal
Solution Approach 1:
The interleaving process is divided into two distinct stages: first permuting cyclic blocks as units, then permuting individual bits within those blocks. This segmentation allows the system to achieve optimal reception performance through careful ordering while maintaining a structured, manageable implementation approach that doesn't excessively increase complexity
Solution Approach 2:
The cyclic blocks are permuted in advance before the actual bit mapping onto constellation words occurs. This preliminary arrangement of blocks based on their importance and robustness characteristics enables the subsequent bit-level mapping to proceed efficiently, achieving optimal performance without requiring complex real-time decisions during the mapping phase
2Reliability
If bits are mapped directly without permutation, then the mapping process is simple, but the bit error rate performance is suboptimal
Solution Approach 1:
Different permutation strategies are applied to different parts of the data structure: cyclic blocks are permuted based on their overall importance and robustness characteristics, while individual bits within blocks are permuted based on their specific positions and roles. This localized quality approach ensures that each part of the codeword is optimally positioned for its specific function, achieving superior bit error rate performance
Solution Approach 2:
The system changes the ordering parameters of both cyclic blocks and individual bits to optimize performance. By adjusting which blocks come first and how bits are arranged within blocks, the system adapts the mapping parameters to achieve optimal bit error rate performance without requiring a complete redesign of the mapping architecture
Data Source
AI summary
An interleaving method performed by a transmitter for a communication system with quasi-cyclic low-density parity-check codes, spatial multiplexing, and T transmit antennas is used for applying permutation to N cyclic blocks of a codeword in order to map bits of the permutated cyclic blocks onto T constellation words constituting multiple spatial-multiplexing blocks from the codeword. Each cyclic block consists of Q bits.