Stepped Hierarchical Modulation Constellation Design
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Solution Overview
Problem
Conventional constellation designs based on M-QAM hierarchical modulation suffer from deteriorated performance and increased error probability, especially in MIMO environments, due to large signal points at quadrangular vertices, necessitating improved error probability reduction.
Innovation Solution
A method and apparatus for designing a constellation using stepped hierarchical modulation, involving a processor and memory to generate an initial θ-QAM constellation, adjust signal points based on a constellation parameter, and map information bits to enhance data protection by increasing distances between signal points and allocating high-priority bits strategically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If M-QAM hierarchical modulation is used with large signal points at quadrangular vertices, then the constellation structure is simple and easy to implement, but the bit error probability increases and performance deteriorates
Solution Approach 1:
The patent transforms the conventional symmetric quadrangular M-QAM constellation into an asymmetric stepped constellation where signal points are relocated to form a stepped pattern. This asymmetry increases the minimum distance between signal points, particularly protecting high-priority bits by positioning them at larger radial distances from the origin, thereby reducing bit error probability while maintaining implementation feasibility
Solution Approach 2:
The patent introduces a radial distance dimension to differentiate signal point importance. By assigning high-priority bits to signal points at larger radial distances and low-priority bits to closer points, the system creates a hierarchical protection structure where the dimension of distance from origin correlates with protection level, effectively reducing error probability for critical data
2Reliability
If signal points are moved to increase minimum distance, then bit error probability decreases, but the constellation complexity increases
Solution Approach 1:
The patent segments the constellation into distinct stepped levels where signal points are grouped at specific radial distances. This segmentation creates a structured hierarchy that simplifies the mapping process while maintaining increased minimum distances between points, reducing complexity compared to arbitrary point placements
3Reliability
If high-priority bits are allocated to signal points with larger distances, then data protection degree increases, but the mapping complexity increases
Solution Approach 1:
The patent applies local quality by assigning different protection levels to different regions of the constellation. High-priority bits are systematically allocated to signal points in outer regions (larger radial distances) while low-priority bits occupy inner regions, creating a localized protection strategy that simplifies mapping rules while enhancing protection for critical data
Data Source
AI summary
Disclosed are a method and an apparatus for a constellation design based on stepped hierarchical modulation. According to the present invention, there is provided an apparatus for a constellation design based on stepped hierarchical modulation comprising a processor and a memory connected to the processor, wherein the memory stores program instructions to be executed by the processor so as to generate an initial constellation including M (M is a natural number) signal points based on stepped θ-QAM, set a constellation parameter to control a degree of data protection, move signal points located in an m-th quadrant by a preset distance in a preset direction by applying the constellation parameter to the initial constellation, and map information bits encoded in the moved signal points.