Non-Uniform Constellation Coding for SNR-Adaptive BICM Capacity
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Solution Overview
Problem
Current coding and modulation systems, particularly in BICM apparatus, face limitations 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 defined by a constellation position vector, allowing for adaptive selection based on channel characteristics and signal-to-noise ratio, to enhance coding and modulation 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 limited and cannot be maximized
Solution Approach 1:
The patent applies local quality by transitioning from uniform constellation points to non-uniform constellation points where each point's position is optimized locally based on channel conditions and SNR. The constellation position vector allows different regions of the constellation to have different spacing and distribution characteristics, maximizing coding capacity in each local region while maintaining overall system performance.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting constellation point positions based on channel characteristics and signal-to-noise ratio. The constellation position vector serves as a parameter set that can be modified according to operating conditions, allowing the system to adapt and maximize coding capacity without increasing fundamental device complexity.
2Productivity
If non-uniform constellation points optimized for specific SNR are used, then coding and modulation capacity is maximized, but adaptability to varying channel conditions decreases
Solution Approach 1:
The patent applies dynamics by making the constellation position vector adjustable and adaptable to varying channel conditions. Instead of using a fixed non-uniform constellation optimized for a specific SNR, the system can dynamically modify the constellation point positions based on current channel characteristics, thereby maintaining both high coding capacity and adaptability across different operating conditions.
Solution Approach 2:
The patent implements universality by designing a constellation structure that can serve multiple functions and adapt to various channel conditions. The non-uniform constellation with adjustable position vector can be configured for different SNR levels and channel types, making it a universal solution that maximizes coding capacity across diverse operating environments rather than being optimized for a single condition.
3Reliability
If constellation points are perturbed from capacity optimized positions, then robustness against channel variations is improved, but coding and modulation capacity decreases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by using a constellation position vector that can be adjusted based on channel conditions. Rather than permanently perturbing points from optimal positions, the system modifies the position parameters dynamically, maintaining capacity optimization when conditions allow while providing robustness when channel variations occur.
Solution Approach 2:
The patent applies feedback by using channel characteristics and SNR information to adjust constellation point positions. The system receives feedback about channel conditions and modifies the constellation position vector accordingly, ensuring that points remain at capacity-optimized positions when possible while adapting to maintain robustness when channel variations occur.
Data Source
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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.