Non-Uniform Constellation Modulation for Adaptive SNR Capacity
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Solution Overview
Problem
Modern communications systems face challenges in maximizing coding and modulation capacity, particularly in fading channels and varying signal-to-noise ratios, where existing methods struggle to optimize constellation points for optimal performance.
Innovation Solution
A coding and modulation apparatus that uses a non-uniform constellation with constellation points optimized based on the signal-to-noise ratio and channel characteristics, defined by specific position vectors for each quadrant, allowing for adaptive selection and optimization of constellation points to enhance coding and modulation capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform constellation is used for coding and modulation, then device complexity is reduced and ease of operation is improved, but coding and modulation capacity is limited and cannot be maximized under varying channel conditions
Solution Approach 1:
The patent applies local quality by using non-uniform constellation points where different regions of the constellation diagram have different spacing and density characteristics. Specifically, constellation points are positioned with varying distances from the origin and different spacing between adjacent points, allowing optimal local packing density in different regions to maximize capacity while maintaining manageable overall structure.
Solution Approach 2:
The patent employs parameter changes by adjusting the positions of constellation points based on channel conditions and signal-to-noise ratio. The constellation points are defined by specific coordinates (e.g., ±1, ±3, ±7, ±9 for 64-QAM) that are optimized for capacity, and the system can adaptively select different constellation configurations based on SNR thresholds and channel state information.
2Productivity
If non-uniform constellation points are optimized for maximum capacity, then coding and modulation capacity is increased, but adaptation to varying signal-to-noise ratio and channel conditions becomes more difficult
Solution Approach 1:
The patent implements dynamics by making the constellation configuration adaptive to changing channel conditions. The system dynamically selects among different non-uniform constellation point sets based on measured signal-to-noise ratio and channel state. For example, at high SNR, a denser constellation configuration is used to maximize capacity, while at low SNR, a sparser configuration is selected to maintain reliability, thus achieving both high capacity and adaptability.
Solution Approach 2:
The patent uses feedback mechanisms where the receiver measures channel conditions and signal quality, then feeds this information back to the transmitter. The transmitter uses this feedback to select the appropriate non-uniform constellation configuration from multiple available options, ensuring optimal performance under current channel conditions while maintaining the ability to adapt to varying SNR and channel characteristics.
3Productivity
If constellation points are densely packed to increase capacity, then data throughput is improved, but error rate increases in fading channels and low signal-to-noise ratio conditions
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the constellation density based on channel conditions. When channel quality is good (high SNR, stable fading), denser constellation points are used to maximize data throughput. When channel quality degrades (low SNR, severe fading), the system transitions to sparser constellation configurations that provide larger minimum distances between points, thereby reducing error rates and improving reliability while maintaining acceptable throughput.
Solution Approach 2:
The patent employs parameter changes by modifying the constellation point coordinates and spacing based on SNR thresholds and channel state indicators. Different parameter sets are defined for different operating conditions, allowing the system to switch between high-density configurations for maximum throughput and low-density configurations for error resilience, thus resolving the trade-off between data throughput and error-free decoding reliability.
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.