887 research outputs found
Simplified Multiuser Detection for SCMA with Sum-Product Algorithm
Sparse code multiple access (SCMA) is a novel non-orthogonal multiple access
technique, which fully exploits the shaping gain of multi-dimensional
codewords. However, the lack of simplified multiuser detection algorithm
prevents further implementation due to the inherently high computation
complexity. In this paper, general SCMA detector algorithms based on
Sum-product algorithm are elaborated. Then two improved algorithms are
proposed, which simplify the detection structure and curtail exponent
operations quantitatively in logarithm domain. Furthermore, to analyze these
detection algorithms fairly, we derive theoretical expression of the average
mutual information (AMI) of SCMA (SCMA-AMI), and employ a statistical method to
calculate SCMA-AMI based specific detection algorithm. Simulation results show
that the performance is almost as well as the based message passing algorithm
in terms of both BER and AMI while the complexity is significantly decreased,
compared to the traditional Max-Log approximation method
Fabrication and Characterization of Layered Transition Metal Dichalcogenides
The goal of my research was to mechanically exfoliate single to few atomic layer samples of Molybdenum Disulfide (MoS2 ), Tungsten Diselenide (WSe2 ), and Tungsten Disulfide (WS2 ) and characterize these 2D materials by multiple methods. I used Atomic Force Microscopy, Raman Spectroscopy, and Optical Microscopy to accomplish this. In addition, I measured the electrical properties of the exfoliated materials by fabricating a device and taking basic measurements
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