Coded Modulation With SPC-LDPC Integration for Adaptive QAM
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Solution Overview
Problem
Existing 5G and 6G wireless communication technologies face challenges in achieving optimal spectral efficiency and reliability due to limitations in modulation techniques, particularly in high throughput channels and varying signal-to-noise ratios, with current methods like probabilistic shaping and multidimensional coded modulation being incompatible and requiring modifications for integration.
Innovation Solution
Implementing a combination of single parity check (SPC) encoding and low-density parity check (LDPC) encoding with a specially designed interleaver and Gray mapping to enhance coded modulation, allowing for compatibility with probabilistic shaping and iterative decoding, thereby improving performance across diverse channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If probabilistic shaping and multidimensional coded modulation are used to improve spectral efficiency, then spectral efficiency increases, but compatibility issues arise and require modifications for integration
Solution Approach 1:
The input data stream is partitioned into two separate bit streams (X1 and X2), where X1 is used for SPC encoding and X2 undergoes LDPC encoding. This segmentation allows independent optimization of different coding schemes for their respective functions, enabling probabilistic shaping through SPC while maintaining LDPC for robust error correction, thus resolving compatibility issues.
Solution Approach 2:
The patent combines SPC encoding and LDPC encoding in a unified coded modulation framework. The SPC-encoded sign bits and LDPC-encoded information bits are merged through interleaving and mapped to QAM symbols together, creating an integrated system that achieves both probabilistic shaping capabilities and multidimensional coded modulation benefits without compatibility conflicts.
2Reliability
If forward error correction rates are adjusted frequently to adapt to varying channel conditions, then reliability improves, but system complexity and adjustment overhead increase
Solution Approach 1:
The system dynamically adapts to varying channel conditions through the flexible interleaver design that can handle different code rates and modulation schemes without requiring frequent reconfiguration. The SPC and LDPC codes work together in a dynamic framework where the interleaver adjusts the mapping between coded bits and modulation symbols, providing adaptability while maintaining system stability.
Solution Approach 2:
The combined SPC-LDPC coding framework serves multiple functions simultaneously: SPC provides probabilistic shaping and basic error protection, LDPC provides robust error correction, and the interleaver handles both code types within a unified structure. This multi-functionality allows the system to adapt to various channel conditions without requiring separate adjustment mechanisms for each coding scheme, reducing overall system complexity.
3Reliability
If SPC encoding is applied to parity bits with first bit stream as padding to obtain sign bits, then coded modulation performance improves, but encoding complexity increases
Solution Approach 1:
The encoding process is segmented into distinct stages: first, the input stream is divided into X1 (padding bits) and X2 (information bits); second, X2 undergoes LDPC encoding to produce parity and information bits; third, SPC encoding is applied specifically to the LDPC parity bits combined with X1 to generate sign bits. This segmentation allows each encoding step to be optimized independently, improving overall performance while managing complexity through modular processing.
Data Source
AI summary
Disclosed is a method comprising, by a transmitter apparatus, partitioning (901) an input data stream to obtain a bit stream X1 and a bit stream X2; subjecting (902) the bit stream X2 to encoding by LDPC encoders, to obtain X2 parity bits, and X2 information bits; applying (903) SPC encoding to the X2 parity bits, together with the bit stream X1, to obtain sign bits, wherein the bit stream X1 is used as padding bits; subjecting (904) the sign bits, the padding bits, and the X2 information bits, to an interleaver operation to obtain an interleaver output; subjecting (905) the interleaver output to Gray mapping to form multiple consecutive quadratic amplitude modulation, QAM, symbols; modulating (905) the QAM symbols by quadratic amplitude modulation to obtain a modulated data stream; and transmitting (906) the modulated data stream via a radio access network or optical fibre communication network.