QAM Coded Modulation with LDPC-SPC Shaping for Variable Channels
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Solution Overview
Problem
Existing 5G NR modulation techniques face limitations in spectral efficiency and channel quality due to the exclusion of coded modulation and probabilistic shaping, which are not compatible without modifications, constraining performance in varying channel conditions.
Innovation Solution
Implementing multidimensional coded modulation with iterative decoding (MDCM-ID) and probabilistic shaping (PS) by using a combination of single parity check (SPC) encoding and low-density parity check (LDPC) codes, along with a specially designed interleaver, to enhance data transmission across diverse channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coded modulation and probabilistic shaping are excluded from 5G NR modulation techniques, then implementation complexity is reduced, but spectral efficiency and channel quality deteriorate
Solution Approach 1:
The input data stream is divided into two separate bit streams (first bit stream X1 and second bit stream X2), which are then processed by different encoding schemes (SPC encoding for sign bits, LDPC encoding for information bits). This segmentation allows the system to apply appropriate coding strategies to different parts of the data, achieving both complexity management and performance improvement.
Solution Approach 2:
The patent combines SPC encoding and LDPC encoding into a unified coded modulation framework. The SPC-encoded sign bits and LDPC-encoded information bits are merged and jointly modulated using QAM, creating a hybrid coding scheme that leverages the strengths of both encoding methods to improve spectral efficiency and channel quality.
2Adaptability or versatility
If coded modulation and probabilistic shaping are excluded from 5G NR modulation techniques, then compatibility issues are avoided, but spectral efficiency deteriorates
Solution Approach 1:
The patent creates a universal modulation framework that can operate in multiple modes. By using SPC encoding for sign bits and LDPC encoding for information bits with QAM modulation, the system achieves compatibility with existing 5G NR infrastructure while simultaneously enabling advanced coded modulation techniques to improve spectral efficiency. The framework can adapt to different channel conditions and requirements.
3Device complexity
If conventional modulation techniques are used without coded modulation, then system simplicity is maintained, but adaptability to varying channel conditions deteriorates
Solution Approach 1:
The patent introduces dynamic adaptability through the coded modulation framework. The SPC and LDPC encoding rates, along with QAM order, can be adjusted based on channel conditions. The interleaver design further enhances adaptability by optimizing bit distribution according to channel characteristics, allowing the system to dynamically respond to varying signal-to-noise ratios and channel quality.
Data Source
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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.