SNR-Adaptive Non-Uniform Constellation Mapping for BICM Decoding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current coding and modulation systems, particularly in BICM apparatuses, face challenges in maximizing coding and modulation capacity due to suboptimal constellation point placement, which affects performance in varying channel conditions and signal-to-noise ratios.
Innovation Solution
A coding and modulation apparatus that uses a non-uniform constellation with optimized constellation points based on the total number of constellation points and signal-to-noise ratio, where constellation points in different quadrants are defined by specific vectors, allowing for adaptive selection based on channel characteristics and SNR, enhancing decoding complexity and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform constellation points are used in BICM apparatus, then device complexity is reduced and ease of operation is improved, but coding and modulation capacity is suboptimal and performance in varying channel conditions deteriorates
Solution Approach 1:
The patent applies local quality by transitioning from uniform constellation point distribution to non-uniform distribution, where different regions of the constellation diagram have different point densities optimized for specific channel conditions. This allows the system to concentrate constellation points in regions that maximize coding and modulation capacity for given SNR levels and channel characteristics, thereby improving productivity without significantly increasing device complexity.
Solution Approach 2:
The patent employs parameter changes by adjusting constellation point positions based on signal-to-noise ratio (SNR) and channel characteristics. The system dynamically modifies the constellation parameters (point locations, densities, and distributions) to optimize performance for different channel conditions, thereby increasing coding and modulation capacity while maintaining manageable device complexity through parameterized designs.
2Productivity
If non-uniform constellation with optimized points is used, then coding and modulation capacity is increased, but device complexity and constellation design difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimized constellation point positions for various SNR levels and channel conditions. These pre-computed non-uniform constellation configurations are prepared in advance and can be directly applied during transmission without real-time optimization computations, thereby increasing coding and modulation capacity while limiting the increase in device complexity through use of pre-computed lookup tables.
Solution Approach 2:
The patent employs dynamics by making the constellation configuration adaptive to changing channel conditions. The system dynamically selects appropriate non-uniform constellation point distributions based on current SNR and channel characteristics, allowing the constellation to adapt its structure to maximize capacity under varying conditions without requiring complex real-time optimization algorithms.
3Reliability
If constellation points are adapted to channel characteristics, then reliability and error-free decoding are improved, but adaptability requirements and system complexity increase
Solution Approach 1:
The patent applies parameter changes by adjusting constellation point positions and distributions according to detected channel characteristics and SNR levels. The system modifies key parameters of the non-uniform constellation (such as point densities in different regions, inter-point distances, and angular positions) to optimize reliability for specific channel conditions, thereby improving error-free decoding performance while managing adaptability requirements through parameterized constellation designs.
Solution Approach 2:
The patent employs feedback mechanisms by using channel quality information and SNR measurements to select appropriate non-uniform constellation configurations. The system receives feedback about channel conditions and adapts the constellation point distribution accordingly, improving reliability by matching the constellation structure to actual channel characteristics while limiting system complexity through discrete, pre-defined adaptation options rather than continuous optimization.
Data Source
AI summary
A coding and modulation apparatus and method are presented. The apparatus (10) comprises an encoder (11) that encodes input data into cell words, and a modulator (12) that modulates said cell words into constellation values of a non-uniform constellation. The modulator (12) is configured to use, based on the total number M of constellation points of the constellation and the signal-to-noise ratio SNR in dB, a non-uniform constellation from a group of constellations comprising one or more of predetermined constellations defined by the constellation position vector w0 . . . b−1, wherein b=M/4.