SCMA Codebook Generation With Small Projections and Lower PAPR
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Solution Overview
Problem
Current SCMA codebooks have a high number of projections per complex dimension, leading to increased decoding complexity and high peak-to-average power ratio (PAPR), which hinders efficient data transmission in wireless communications.
Innovation Solution
Designing SCMA codebooks with a small number of projections per complex dimension and utilizing dimension-switched PSK constellations to reduce PAPR, while maintaining dependency among constellation points for performance, using techniques such as lattice constellations and message passing algorithms for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional SCMA codebooks with high number of projections per complex dimension are used, then spectral efficiency is improved, but decoding complexity increases
Solution Approach 1:
The codebook design segments the complex dimension projections into a smaller number of distinct projection points. By reducing the number of projections per complex dimension while maintaining the overall codebook structure, the patent achieves lower decoding complexity through simplified message passing algorithms while preserving spectral efficiency through optimized constellation design
Solution Approach 2:
The patent changes the parameter of projections per complex dimension from high to small. This parameter change is achieved through optimized constellation design and lattice-based codebook construction, which maintains the essential functionality for spectral efficiency while dramatically reducing the number of projection points that contribute to decoding complexity
2Productivity
If conventional SCMA codebooks are used, then data transmission capability is improved, but peak-to-average power ratio (PAPR) increases
Solution Approach 1:
The patent applies parameter changes to reduce PAPR by optimizing the constellation design and codebook structure. Through careful selection of constellation points and projection configurations, the patent maintains data transmission capability while controlling the peak power characteristics to reduce the PAPR metric
Solution Approach 2:
The patent employs dimension-switched PSK constellations that dynamically switch between different dimensional representations. This dynamic approach allows the system to adapt the projection behavior to minimize peak power occurrences while maintaining overall data transmission capability through flexible constellation switching
3Device complexity
If small projections per complex dimension are used, then decoding complexity is reduced, but constellation design complexity increases
Solution Approach 1:
The patent segments the constellation design into structured lattice-based constructions and optimized projection patterns. By organizing the constellation design around regular lattice structures with predetermined projection points, the patent reduces the apparent design complexity while achieving the desired small projections per complex dimension
Solution Approach 2:
The patent changes the design approach from arbitrary constellation design to systematic lattice-based construction. This parameter change in the design methodology provides structured patterns that simplify the overall design process while achieving the target of small projections per complex dimension through optimized lattice configurations
Data Source
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AI summary
A method for data transmission by a device in a communication system includes modulating a first data stream using a codebook to produce a second data stream, wherein the codebook is in correspondence with a multi-dimensional modulation map that includes a number of distinct projections per complex dimension that is smaller than a number of modulation points of the multi-dimensional modulation map, and transmitting the second data stream over allocated resources in the communication system.