PLC and VLC Cascade Communication System Based on CNDM-OFDM

Fig. 12. Waveforms of off-line modulation and reception of cascaded systems. (a) Waveform obtained by off-line modulation at the transmitter; (b) waveform received by the cascaded system

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Fig. 13. Constellation diagram of the received signal of the cascaded system

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Table 1. Frame parameters of multi-segment joint control signals

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Table 1. Frame parameters of multi-segment joint control signals

Parameter	Value
Data subcarrier $N_{S D}$	48
Pilot subcarrier $N_{S P}$ Total number of subcarriers $N_{S T}$	4 52=48+4
Channel bandwidth /MHz	20
Subcarrier interval $Δ_{F}$ /MHz	0.315
IFFT/FFT period $T_{F F T}$ /μs	3.2=1/ $Δ_{F}$
GI duration $T_{G I}$ /μs	0.8= $T_{F F T}$ /4
Training sequence GI duration $T_{G I 2}$ /μs	1.6= $T_{F F T}$ /2
Preamble duration $T_{P r e a m b l e}$ /μs	16= $T_{S h o r t} + T_{L o n g}$
Mark space $T_{S Y M}$ /μs	1.6= $T_{F F T}$ + $T_{G I}$
Short training sequence duration $T_{S h o r t}$ /μs	8=10 $T_{F F T}$ /4
Long training sequence duration $T_{L o n g}$ /μs	8= $T_{G I 2}$ +2 $T_{F F T}$
Symbolic number of OFDM $N_{S Y M}$	64

Table 2. Simulation parameters of PLC channel multipath attenuation (6-path)
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Table 2. Simulation parameters of PLC channel multipath attenuation (6-path)
$k$ $α_{0}$ $α_{1}$ $i$ $g_{i}$ $d_{i} / m$
1 $- 2.1 \times 10^{- 3}$ $8.11 \times 10^{- 10}$ 1 0.540 200.0
2 0.275 221.0
3 -0.150 242.0
4 0.080 259.0
5 -0.030 266.0
6 -0.020 530.0

Table 3. Gain simulation parameters of VLC channel

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Table 3. Gain simulation parameters of VLC channel

Parameter	Value
Room size /（m×m×m）	4×4×3
NLOS cutoff frequency /MHz Detector physical area of PD /m²	8.5 5×10^-6
Distance between LED and PD /m	2.25
FOV of a receiver PD /（°）	60
Radiation angle of emitter LED /（°）	70
Average reflectivity of the wall	0.8
LOS channel gain /dBm	5.3×10^-4
NLOS channel gain /dBm	1.3×10^-4

Table 4. Parameters for the hierarchical simulation environment of the cascaded system

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Table 4. Parameters for the hierarchical simulation environment of the cascaded system

Parameter	Value
PLC-VLC system mapping mode	QPSK/BPSK/16QAM
PLC-VLC system modulation IFFT/FFT size	FFT-OFDM 64
Number of effective subcarriers	52
Number of cyclic prefixes	16
DC bias coefficient /dB	4
Clipping factor /dB	3

Table 5. Parameters of the cascade system

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Table 5. Parameters of the cascade system

Parameter	Value
LED luminous power /W	1
LED bandwidth /MHz APD effective photosensitive area φ /μm	<5 500
APD spectral response range /nm	400-1100
Plano convex lens /mm	80
Blue filter /mm	80
Power line length /m	5
Transceiver distance /cm	20