Broadcast Constellation Mapping Beyond Uniform QAM Limits
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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 simplicity is maintained, but BER/FER performance falls significantly below Shannon limit
Solution Approach 1:
The patent applies parameter changes by transitioning from uniform QAM parameters (equal spacing, square geometry) to non-uniform QAM parameters (variable spacing, optimized geometry). The constellation points are repositioned with different distances from the origin and non-uniform spacing to maximize information transmission efficiency and approach the Shannon limit, while maintaining practical mapping feasibility through structured design
2Reliability
If non-uniform constellation is implemented, then BER/FER performance approaches Shannon limit, but constellation design complexity increases
Solution Approach 1:
The patent applies local quality by optimizing different regions of the constellation diagram with different properties. Inner constellation points have different spacing and positioning characteristics compared to outer points, with each region tailored to maximize performance for its specific signal-to-noise ratio conditions. This localized optimization allows the overall system to approach the Shannon limit while maintaining manageable complexity through region-based design
3Reliability
If non-uniform constellation is implemented, then BER/FER performance approaches Shannon limit, but mapping complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the non-uniform constellation into structured groups and layers. Constellation points are organized in concentric rings or geometric patterns with systematic indexing, allowing the mapper to select points based on predefined rules rather than arbitrary positions. This segmented structure reduces mapping complexity by providing a systematic approach to selecting and indexing non-uniform constellation points
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.