Non-Uniform Constellation Mapping for Broadcast BER Improvement
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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 square shape and uniform distance properties of traditional uniform QAM, optimizing constellation design for specific signal-to-noise ratios (SNR) and fading channels to enhance BER and 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 gap from Shannon limit is large 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 reduce the gap to Shannon limit while maintaining manageable mapping complexity
Solution Approach 2:
The patent changes the fundamental parameter of constellation uniformity by transitioning from uniform QAM to non-uniform constellation. This involves modifying the amplitude and phase parameters of constellation points to create optimized distributions that achieve better performance接近Shannon limit while still allowing for practical implementation
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 optimized non-uniform constellation patterns in lookup tables or memory. The receiver has these constellation patterns pre-loaded, allowing for complex non-uniform demapping without requiring complex real-time calculation, thus achieving better performance while managing implementation complexity
Solution Approach 2:
The patent introduces dynamics by making the constellation configuration adaptable to different transmission conditions. The system can switch between different non-uniform constellation patterns based on channel conditions, SNR levels, or service requirements, allowing optimization for specific scenarios while maintaining flexibility
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.