Non-Uniform Constellation Mapping for BICM Broadcast Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current broadcasting systems using Bit Interleaved and Coded Modulation (BICM) with uniform Quadrature Amplitude Modulation (QAM) fall short of optimal performance due to suboptimal bit error rate (BER) and frame error rate (FER) performance, as they do not efficiently utilize signal-to-noise ratio (SNR) and coding rate variations.
Innovation Solution
The implementation of non-uniform constellations (NUC) that relax the rectangular shape and uniform spacing constraints of traditional QAM, optimizing constellation points for specific SNR conditions in various fading channels to enhance BER and FER performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform QAM is used for modulation, then the mapping and demapping process is simple and easy to implement, but the bit error rate performance and frame error rate performance are suboptimal and far from the Shannon limit
Solution Approach 1:
The patent applies local quality by transitioning from uniform QAM spacing to non-uniform constellation point spacing, where different regions of the constellation diagram have different point densities optimized for specific SNR conditions. This allows the system to achieve better BER performance in fading channels while maintaining practical implementation complexity through pre-computed lookup tables and standardized mapping procedures.
2Productivity
If higher QAM size is used to increase throughput, then the data rate increases, but the system becomes more sensitive to noise and channel conditions
Solution Approach 1:
The patent implements dynamics by introducing adaptive modulation schemes where the constellation size and spacing can be dynamically adjusted based on channel conditions. The system can switch between different QAM orders (16QAM, 64QAM, 256QAM, 1024QAM) and use non-uniform spacing configurations that optimize the trade-off between throughput and noise sensitivity for current channel quality.
3Reliability
If non-uniform constellation is used to reduce gap to Shannon limit, then bit error rate and frame error rate performance improve, but the complexity of constellation design and implementation increases
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing optimal non-uniform constellation configurations in lookup tables before transmission. The receiver and transmitter are configured with these pre-designed constellations for different SNR conditions and fading channel types, eliminating the need for real-time optimization calculations and reducing implementation complexity while maintaining optimal performance.
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.