Higher-Order Modulation Mapping for Lower SNR Demodulation
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Solution Overview
Problem
Higher order modulation in communications systems requires a larger signal-to-noise ratio (SNR), leading to increased bit error rates, which existing technologies have not adequately addressed.
Innovation Solution
A modulation method that maps bits from multiple code words into a single symbol, using serial-to-parallel conversion and delay processing to enhance demodulation accuracy, thereby reducing the SNR requirement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher order modulation is used to improve spectrum efficiency, then spectrum efficiency is improved, but signal-to-noise ratio requirement increases
Solution Approach 1:
The code word sequence is segmented into M sequences through serial-to-parallel conversion, where each sequence contains N/M bits from a code word. This segmentation allows bits from the same code word to be distributed across different sequences, enabling the modulator to map bits from multiple code words into a single symbol while maintaining error correction capabilities.
Solution Approach 2:
The modulator performs preliminary mapping of bits from multiple code words into a single symbol before modulation. By pre-organizing bits from different code words (including the first code word and at least one other code word) into the symbol structure, the system prepares the signal in advance to utilize redundancy information, thereby reducing the SNR requirement for higher order modulation.
2Speed
If higher order modulation is used to increase transmission rate, then transmission rate is improved, but bit error rate increases
Solution Approach 1:
The system utilizes feedback from multiple code words in the mapping process. By incorporating bits from the first code word and at least one other code word into each symbol, the modulator creates an inherent feedback mechanism where information from previously transmitted code words helps in the demodulation and error correction of current symbols, thereby reducing bit error rate despite higher modulation order.
Solution Approach 2:
The modulation scheme creates a composite signal structure where each symbol is composed of bits from multiple code words rather than a single code word. This composite approach combines the strengths of multiple coded sequences, providing both high transmission rate through higher order modulation and improved reliability through diversified error correction capabilities.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Embodiments of this application provide a modulation method and apparatus. The method includes: receiving a code word sequence, where each code word includes N bits, and the code word sequence includes at least a first code word; mapping the code word sequence into M sequences, where each sequence includes N/M bits from the first code word; mapping the M sequences into a symbol sequence, where each symbol is corresponding to M bits, the M bits are respectively from the M sequences, first bits corresponding to N/M first-type symbols are from the first code word, and second bits corresponding to N/M second-type symbols are from the first code word. As a result, a first bit corresponding to the second-type symbol is definitely from another code word different from the first code word. A bit in the second-type symbol and from the another code word may be demodulated by using information about the first code word, so that the bit in the second-type symbol and from the another code word can be demodulated more accurately, thereby lowering a signal-to-noise ratio requirement during higher order modulation.