Codeword Interleaved Modulation for Lower-SNR Higher-Order Demodulation
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Solution Overview
Problem
Higher order modulation in communications systems requires a larger signal-to-noise ratio (SNR), leading to a higher bit error rate, which is challenging to manage effectively.
Innovation Solution
A modulation method that maps code words into multiple sequences, where each symbol corresponds to bits from different code words, allowing for more accurate demodulation by using information from the first code word to demodulate bits from another code word, 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. This segmentation allows the system to process and demodulate bits from different code words separately, improving demodulation accuracy and reducing the SNR requirement while maintaining higher order modulation for spectrum efficiency.
Solution Approach 2:
The system performs preliminary decoding of the first code word to obtain decoded information before using it to demodulate bits from subsequent code words. This preliminary action enables the second-type symbols to be demodulated with assistance from previously decoded information, reducing the SNR requirement for higher order modulation.
2Productivity
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 uses feedback from the decoded first code word to assist in demodulating subsequent code words. The decoded information from previous code words serves as feedback that improves the accuracy of demodulating current code words, thereby reducing bit error rate while maintaining high transmission rate through higher order modulation.
Solution Approach 2:
The system performs preliminary decoding of earlier code words before demodulating later code words. This preliminary action provides reliable reference information that reduces the bit error rate in higher order modulation schemes where transmission rate is increased.
Data Source
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. Thus a signal-to-noise ratio requirement during higher order modulation lowered.