Broadcast Modulation Mapping With Non-Uniform Constellations
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Solution Overview
Problem
Current broadcasting systems, such as DVB-T2, utilize uniform QAM constellations that leave a significant gap from the theoretical Shannon limit, resulting in suboptimal bit error rate (BER) and frame error rate (FER) performance.
Innovation Solution
The implementation of non-uniform constellations (NUC) that relax the rectangular shape and uniform spacing properties of traditional uniform QAM, optimizing constellation design based on signal-to-noise ratio (SNR) and coding rate to improve BER/FER performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform QAM constellation is used, then mapping and demapping is easy, but the capacity leaves a big gap from the Shannon limit resulting in suboptimal BER/FER performance
Solution Approach 1:
The patent applies local quality by creating different constellation point densities in different regions of the complex plane. The non-uniform constellation has higher density in some regions and lower density in others, optimizing the distribution of signal points to better match the statistical properties of the channel and improve BER/FER performance while maintaining reasonable mapping complexity
Solution Approach 2:
The patent changes the fundamental parameter of constellation point distribution from uniform to non-uniform. By modifying the density and positioning parameters of constellation points, the system achieves better capacity utilization and approaches the Shannon limit while still maintaining practical mapping and demapping operations
2Reliability
If non-uniform constellation is used, then the gap from Shannon limit is reduced improving BER/FER performance, but the constellation design becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-defining and storing the non-uniform constellation point positions and their corresponding bit mappings. The receiver is pre-configured with the same constellation structure, allowing for optimized performance without requiring complex real-time calculations during transmission and reception operations
Data Source
AI summary
A transmitting apparatus is disclosed. The transmitting apparatus includes an encoder to perform channel encoding with respect to bits and generate a codeword, an interleaver to interleave the codeword, and a modulator to map the interleaved codeword onto a non-uniform constellation according to a modulation scheme, and the constellation may include constellation points defined based on various tables according to the modulation scheme.