Non-Uniform Constellation Modulation for Capacity and Error Reduction
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Solution Overview
Problem
Existing coding and modulation systems face challenges in maximizing capacity, reducing bit error rates, and achieving reliable reception with reduced signal-to-noise ratio (SNR) in communication systems.
Innovation Solution
A coding and modulation apparatus that uses a non-uniform constellation, optimized based on the total number of constellation points and the code rate, to encode and modulate input data. This apparatus selects from various groups of constellations, including those defined by specific constellation position vectors, to achieve enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform constellation is used for modulation, then the system is simple to implement, but the capacity is not maximized and bit error rate is higher
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. Specifically, constellation points are strategically positioned with varying distances from the origin and from each other, creating local variations in signal spacing that optimize both capacity and error performance for different channel conditions.
Solution Approach 2:
The patent changes the fundamental parameter of constellation point distribution from uniform to non-uniform. The modulation scheme uses varied amplitude and phase values for different constellation points, allowing the system to adapt the signal characteristics to maximize capacity while maintaining implementation feasibility through standardized modulation techniques.
2Reliability
If higher SNR is used for reception, then reception reliability improves, but the system requires more signal power
Solution Approach 1:
The non-uniform constellation creates local quality variations where certain constellation points are positioned to provide better noise immunity. Points representing critical data transitions are placed with greater spacing or in regions of the constellation diagram that are more resistant to noise, allowing reliable reception at lower overall SNR levels.
Solution Approach 2:
The patent applies preliminary action by pre-optimizing the constellation point positions before transmission. The non-uniform distribution is calculated and configured in advance to anticipate channel conditions and noise characteristics, positioning points to maximize robustness against expected interference and fading, thereby reducing the power needed to achieve reliable reception.
3Reliability
If non-uniform constellation is used, then capacity increases and bit error rate reduces, but the modulation complexity increases
Solution Approach 1:
The patent manages complexity by applying local quality only where necessary - specifically in the positioning of constellation points - while maintaining standard modulation architecture elsewhere. The non-uniform distribution is implemented through lookup tables or pre-calculated mapping, keeping the actual modulation process relatively simple despite the optimized point positions.
Data Source
AI summary
A coding and modulation apparatus and method are presented. The apparatus comprises an encoder that encodes input data into cell words, and a modulator that modulates said cell words into constellation values of a non-uniform constellation. The modulator is configured to use, based on the total number M of constellation points of the constellation and the code rate, a non-uniform constellation from one or several groups of constellations each comprising one or more constellations.