Broadcast Signal Mapping with Non-Uniform Constellation Tables
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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 points for better performance based on signal-to-noise ratio (SNR) and coding rate.
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 and capacity utilization deteriorate due to large gap from Shannon limit
Solution Approach 1:
The patent applies local quality by transitioning from uniform spacing to non-uniform spacing of constellation points. Different regions of the constellation diagram have different point densities and spacing characteristics, allowing optimization for specific channel conditions while maintaining manageable complexity through structured design
Solution Approach 2:
The patent changes the fundamental parameter of constellation point spacing from uniform to non-uniform. This parameter change enables the system to achieve better BER/FER performance and capacity utilization by matching the constellation structure to channel characteristics, while the changes are implemented through predefined patterns rather than continuous optimization
2Reliability
If non-uniform constellation is used, then BER/FER performance and capacity utilization improve, but mapping and demapping complexity increases due to relaxed rectangular shape and uniform spacing properties
Solution Approach 1:
The patent applies segmentation by dividing the non-uniform constellation into structured regions or groups with specific spacing patterns. This segmentation allows the receiver to process different regions using simplified rules rather than requiring complex global optimization, reducing demapping complexity while maintaining performance benefits
Solution Approach 2:
The patent applies preliminary action by pre-defining and pre-optimizing the non-uniform constellation patterns during system design or initialization. The optimal spacing and positioning are calculated in advance based on channel characteristics, and these pre-computed patterns are then used during transmission without requiring real-time complex calculations at the receiver
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.