Non-Uniform Constellation Coding With Condensed Signal Points
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Solution Overview
Problem
Modern communications systems face challenges in maximizing coding and modulation capacity while minimizing storage and demodulation complexity, particularly in achieving optimal performance across varying signal-to-noise ratios and channel conditions.
Innovation Solution
A coding and modulation apparatus that uses a non-uniform constellation with optimized constellation points based on signal-to-noise ratio and channel characteristics, dynamically reducing the number of constellation points to enhance performance and reduce complexity, utilizing a method that condenses constellation points close to each other and selects constellations based on specific SNR and channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large number of constellation points are used to maximize coding and modulation capacity, then the coding and modulation capacity is improved, but the storage and demodulation complexity increases
Solution Approach 1:
The patent merges multiple preliminary optimized constellation points that are located close to each other into a single condensed constellation point. This consolidation reduces the total number of constellation points from 1,048,576 to 2,000 for 1024k N2-QAM, thereby reducing storage and demodulation complexity while maintaining high coding and modulation capacity through the use of non-uniform constellation positioning
Solution Approach 2:
The patent changes the parameters of constellation points by optimizing their positions based on signal-to-noise ratio and channel characteristics to form non-uniform constellations. This parameter optimization allows the system to achieve high capacity with fewer effective constellation points after condensation, resolving the contradiction between capacity and complexity
2Device complexity
If constellation points are condensed to reduce the number of points, then storage and demodulation complexity is reduced, but coding and modulation capacity may be degraded
Solution Approach 1:
The patent performs preliminary optimization of constellation points before condensation, where constellation points are pre-positioned to maximize capacity for given SNR and channel conditions. This preliminary action ensures that even after condensing multiple points into one, the remaining constellation structure maintains high coding and modulation capacity
Solution Approach 2:
The patent applies different condensation strategies to different regions of the constellation based on local point density and importance. By selectively merging only those points that are close together while preserving the overall non-uniform structure optimized for capacity, the system reduces complexity without significant capacity degradation
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 constellations defined by a constellation position vector comprising a predetermined number of constellation positions, wherein in one or more constellation position vectors two or more constellation positions are identical resulting from a condensation of preliminary constellation positions optimized before.