generation of screen ofdm - wordpress.com · 2020. 2. 8. · allocation of 2d pilots 5 screen...
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Generation of screen OFDMTrang Nguyen
Specifications
Generation of spatial Cyclic Prefix for OFDM symbol
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Specifications
Screen ACO-OFDM ClippingClipping for limiting PAR
Example of 1D-waveform clipping
▪ Top-clipping is needed after Zero-clipping of ACO-OFDM
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Specifications
Analysis for choosing clipping thresholds
Impact of clipping
Example of balanced clipping in
spatial OFDM symbol
▪ Balanced-clipping is needed for spatial DCO-OFDM
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Specifications
Pilot-assisted linear channel estimation
Simulation of pilot-assisted equalization
Allocation of 2D pilots
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Screen ACO-OFDM
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QAM mapping
Hermitian mapping
2D-IFFTAdding
CPClipping
Pixels display
data1D
2D 2D 2D
2D
1D
𝑋4×4 =
0 𝑥1 0 𝑥40 𝑥2 0 𝑥30 𝑥3 0 𝑥20 𝑥4 0 𝑥1
ACO-OFDM
– Target Tx dimension-
2M column
2Nrow
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ACO-OFDM
– Hermitian Mapping -
ACO-OFDM
– 2D IFFT outputs are real values -
Imaginary part =0
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ACO-OFDM
– Zero clipping-
ACO-OFDM
– Scaling with pixel intensity range: 0-255 -
Min pixel Intensity =0
Max pixel Intensity =255
Average power
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ACO-OFDM
– Demodulation example-
ACO-OFDM
– Linear equalizer for 4-QAM-
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ACO-OFDM
– Linear equalize for 4-PAM-
ACO-OFDM
– Constellation diagram-
White noise: std. deviation =5
White noise: std. deviation =10
White noise: std. deviation =15
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Screen DCO-OFDM
QAM mapping
Hermitian mapping
2D-IFFTAdding
CPDC and Clipping
Pixels display
data1D
2D 2D 2D
2D
1D
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11 01
00
2D IFFT
Real
Values
Hermitian
mappingIm
Re
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DCO-OFDM
– Target Tx dimension-
2M+1 column
2N+1row
DCO-OFDM
– Hermitian Mapping -
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DCO-OFDM
– 2D IFFT outputs are real values -
Imaginary part =0
DCO-OFDM
– Both-sided clipping –
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DCO-OFDM
– Both-sided clipping –
DCO-OFDM
– Scaling and DC bias adding-
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DCO-OFDM
– Bit sequence comparison
Error occurs at the starting and ending frequencies
DCO-OFDM
– Bit sequence comparison
Error occurs at the starting and ending frequencies
ErrorError
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DCO-OFDM
– Hermitian Mapping -
Proposed Solution: Zero bolder is added to protect the inner part (as a guard band)
DCO-OFDM
– 2D IFFT outputs are real values -
Imaginary part =0
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DCO-OFDM
– Scaling and DC bias adding-
DCO-OFDM
– Sampling Phase shift and Equalization-
Measurement of phase shift in 4-QAM showing in constellation diagram
Correction of phase shift in 4-QAM using equalization
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DCO-OFDM
– Bit sequence comparison
DCO-OFDM
– Constellation diagram-
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