M-Dimensional Modulation Constellation for SCMA Demodulation
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G networks, face challenges in accommodating a large number of users and providing high spectral efficiency due to the limitations of orthogonal multiple access technologies, leading to increased complexity in demodulating modulation symbols in sparse code multiple access (SCMA) systems.
Innovation Solution
The proposed method generates a codebook based on an M-dimensional modulation constellation, where constellation points are adjusted by amplifying or reducing the power of real and imaginary parts differently for different data layers, and information bits are mapped across multiple constellations to reduce demodulation complexity, allowing for efficient data transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If orthogonal multiple access technology is used, then system implementation is simple, but network capacity and spectral efficiency are limited
Solution Approach 1:
The invention segments the modulation process into multiple independent constellations (first constellation for real parts, second constellation for imaginary parts). Each constellation can be independently designed and optimized, allowing non-orthogonal multiple access to be implemented through modular constellation designs rather than requiring complete system redesign, thus maintaining implementation simplicity while enabling higher network capacity
Solution Approach 2:
The invention transitions from traditional two-dimensional complex constellation representation to a four-dimensional representation by separating real and imaginary parts into independent constellations. This dimensional expansion enables more sophisticated codebook designs for non-orthogonal multiple access, increasing network capacity while keeping each individual constellation relatively simple
2Quantity of substance
If non-orthogonal multiple access (SCMA) technology is used, then network capacity and spectral efficiency are improved, but demodulation complexity increases significantly
Solution Approach 1:
The invention segments the demodulation process into two independent steps: first demodulating the real part through the first constellation, then demodulating the imaginary part through the second constellation. This segmentation transforms a single complex demodulation operation into two simpler independent operations, significantly reducing demodulation complexity while preserving the network capacity benefits of SCMA
Solution Approach 2:
Instead of mapping information bits directly to complex constellation points as in traditional SCMA, the invention inverts the approach by separately mapping information bits to real-part constellation points and imaginary-part constellation points. This inversion simplifies the demodulation process at the receiver, as each part can be independently decoded without requiring complex joint detection algorithms
Data Source
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AI summary
A data transmission method and apparatus are provided. The method includes: modulating, based on a codebook, every N information bits of to-be-transmitted data into one M-dimensional modulation symbol, where the codebook is generated based on an M-dimensional modulation constellation, the M-dimensional modulation constellation includes M modulation constellations, a constellation point in an mth constellation in the M constellations is obtained by mapping N information bits based on an mth information bit subset, the mth information bit subset includes information bits on some locations in the N information bits, and a union set of M information bit subsets respectively corresponding to the M constellations is the N information bits, where M and N are integers greater than or equal to 2, and m is 1, 2, ..., or M; and sending the generated M-dimensional modulation symbol. The technical solutions can reduce complexity when a modulation signal is demodulated.