Constellation Mapping for Broadcast Transmitters Using Non-Uniform QAM
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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 improve 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 simple and easy to implement, but the capacity leaves a big gap from the theoretical Shannon limit resulting in suboptimal BER/FER performance
Solution Approach 1:
The patent applies local quality by transitioning from uniform QAM spacing to non-uniform constellation point distribution. Different regions of the constellation diagram have different spacing characteristics optimized for specific SNR ranges and fading channel conditions, allowing the system to achieve better BER/FER performance while maintaining practical implementability through structured non-uniform patterns
Solution Approach 2:
The patent changes the fundamental parameter of constellation point spacing from uniform to non-uniform distribution. By optimizing the spacing parameters based on specific SNR values and fading channel characteristics, the system closes the gap to the Shannon limit and improves reliability without sacrificing excessive complexity
2Reliability
If non-uniform constellation is used, then the gap from Shannon limit is reduced and BER/FER performance is improved, but the constellation design becomes more complex requiring optimization for specific SNR and channel conditions
Solution Approach 1:
The patent manages complexity by implementing local quality through region-specific optimization within the constellation diagram. Different areas have different spacing characteristics tailored to local performance requirements, achieving improved reliability while maintaining a structured design that is more manageable than completely arbitrary non-uniform patterns
Solution Approach 2:
The patent controls design complexity by systematically changing spacing parameters based on predefined SNR ranges and channel conditions. Rather than requiring complex real-time optimization, the system uses predetermined parameter sets that achieve near-Shannon-limit performance with manageable implementation complexity
3Ease of manufacture
If uniform spacing between constellation points is maintained, then the constellation structure is simple and easy to implement, but the capacity and transmission efficiency are suboptimal
Solution Approach 1:
The patent resolves this contradiction by applying local quality through non-uniform spacing where different regions of the constellation have different point densities. This allows the system to achieve higher transmission efficiency by optimizing point distribution for specific channel conditions while maintaining implementation simplicity through structured patterns rather than arbitrary arrangements
Solution Approach 2:
The patent applies dynamics by making the constellation spacing adaptable to different operating conditions. The spacing parameters are optimized for specific SNR values and fading channel characteristics, allowing the system to dynamically adjust its effective capacity and transmission efficiency based on channel state while maintaining a finite set of implementable patterns
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.