Transmitter Mapping with Non-Uniform Constellations for Lower BER
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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 design for specific signal-to-noise ratios (SNR) and coding rates using algorithms to enhance BER and FER performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform QAM constellation is used, then mapping and demapping simplicity is maintained, but BER and FER performance is suboptimal with significant gap from Shannon limit
Solution Approach 1:
The patent applies local quality by creating non-uniform spacing between constellation points, where different regions of the constellation have different point densities optimized for specific SNR ranges. This allows the system to achieve better BER and FER performance by concentrating points in regions that are most beneficial for the given channel conditions, rather than using uniform spacing throughout.
Solution Approach 2:
The patent changes the geometric parameters of the constellation from uniform to non-uniform spacing. By optimizing parameters such as point distances, angles, and positions based on target SNR and coding rate, the system achieves improved reliability while managing complexity through algorithmic optimization during constellation design phase.
2Reliability
If non-uniform constellation is used, then BER and FER performance is improved, but mapping and demapping complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing optimized non-uniform constellation parameters (point positions, distances, angles) during system design or initialization phase. These pre-calculated parameters are then used during actual transmission without real-time computation, reducing the operational complexity of mapping and demapping while maintaining the performance benefits of non-uniform spacing.
3Reliability
If constellation is optimized for specific SNR and coding rate, then performance approaches Shannon limit, but adaptability to varying conditions decreases
Solution Approach 1:
The patent applies dynamics by enabling the system to select from multiple pre-defined non-uniform constellation configurations, each optimized for different SNR ranges and coding rates. The system can dynamically switch between these configurations based on current channel conditions, maintaining optimal performance across varying environments rather than being fixed to a single constellation design.
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.