Non-Uniform Constellation Mapping for BER and FER Improvement
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Solution Overview
Problem
Current broadcasting systems, such as DVB-T2, utilize uniform QAM constellations which 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 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 and simple, 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 transitioning from uniform spacing to non-uniform spacing in the QAM constellation, where different regions of the constellation have different point densities optimized for specific SNR conditions. This allows the system to achieve better BER/FER performance by concentrating points in regions that maximize information transmission efficiency under given channel conditions, while maintaining manageable complexity through structured design of the non-uniform pattern.
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 and needs optimization for specific SNR
Solution Approach 1:
The patent applies parameter changes by systematically varying the constellation parameters (point positions, spacing, and distribution) based on target SNR values. Different non-uniform constellations are designed for different SNR ranges, allowing the system to optimize performance for specific operating conditions. This structured approach to parameter variation manages design complexity by providing a framework for selecting appropriate constellations rather than requiring arbitrary design for each scenario.
Solution Approach 2:
The patent applies dynamics by making the constellation configuration adaptable to different SNR conditions and fading channels. The system can dynamically select or switch between different non-uniform constellation designs based on current channel conditions, allowing optimization of BER/FER performance while managing complexity through conditional selection rather than fixed design.
3Adaptability or versatility
If uniform QAM is used, then the system does not need optimization as a function of SNR or coding rate, but the capacity is far from optimal
Solution Approach 1:
The patent applies parameter changes by creating multiple non-uniform constellation configurations optimized for different SNR values and coding rates. This allows the system to adapt transmission capacity to channel conditions by selecting the appropriate constellation parameters, thereby maximizing productivity while maintaining manageable adaptability through structured parameter sets designed for specific operating conditions.
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.