icufn receiver power and snr optimization for visible light communication
DESCRIPTION
Optimize the link quality provided by Visible Light Communication system by changing LED layout placementTRANSCRIPT
Received Power and SNR Optimiza-tion for Visible Light Communica-
tion system
Received Power and SNR Optimiza-tion for Visible Light Communica-
tion system
Do Trong Hop
Advanced Network Design & Analysis labSoongsil University
2
ContentContentMulti-objective Optimization
Visible Light Communication system
Received Power and SNR Optimization
Conclusion
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Multi-objective OptimizationMulti-objective OptimizationWhat is multi-objective optimization?
Multi-objective optimization (MOO) is the process of simul-taneously optimizing two or more conflicting objectives subject to certain constraintsExample:
Maximizing profit and minimizing the cost of a productMaximizing performance and minimizing fuel consumption of a vehicle
Why do we need MOO?There are trade-off between two or more objectivesWith single-objective optimization, upgrading one objec-tive leads to degrading the others.
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Multi-objective OptimizationMulti-objective OptimizationDefinition of “” in maximization problem
are objectives are two solutions () when
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Multi-objective OptimizationMulti-objective OptimizationDefinition of “” in maximization problem
are objectives are two solutions () when
better
𝑎
𝑓 2
𝑓 1
𝑏𝒂≻𝒃
worse
wors
ebett
er
6
Multi-objective OptimizationMulti-objective OptimizationDefinition of “” in maximization problem
are objectives are two solutions () when
7
Multi-objective OptimizationMulti-objective OptimizationDefinition of “” in maximization problem
are objectives are two solutions () when
better
𝑎
𝑓 2
𝑓 1
𝑏
worse
wors
ebett
er
8
Multi-objective OptimizationMulti-objective OptimizationWhat MOO does
better
Non-dominated solutions
𝑓 2
𝑓 1
Dominated solutions
worse
wors
ebett
er
MOO process finds all non-dominated solutions
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Multi-objective OptimizationMulti-objective OptimizationFormulation
Solution methods for MOOConstructing a single aggregate objective function (AOF)Evolutionary algorithm (e.g. NGSAII, SPEA2)Other methods
1 2minimize [ ( ), ( ), ..., ( )]
. .
( ) 0
( ) 0
T
nf x f x f x
x
s t
g x
h x
x X
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Visible light communicationVisible light communicationVisible light communication (VLC) system is a system using visible light from LEDs to transmit data.
VLC – candidate for the next generation of indoor wireless communi-cation
VLC
High power illuminating
Broadband link communica-tion
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Visible light communicationVisible light communicationCommunication link provided by VLC system
A high quality link provided by VLC system requires:High signal-to-noise ratio (SNR)High received power
Received power and SNR is greatly affected by LED layout setting
There is trade-off between received power and SNR
0 10 20 30 40 50-0.5
0
0.5
1
1.5
2
2.5
Z [deg]
Ave
rage
rec
eive
d po
wer
[dB
m]
Average received power and SNR corresponding to different LED zenith angle Z in VLC sys-tem
0 5 10 15 20 25 30 35 40 45 5018
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20
21
22
23
24
25
Z [deg]
Av
erag
e S
NR
[d
B]
12Received power and SNR opti-mizationReceived power and SNR opti-mization
Optimize quality of the link provided by VLC system
Simultaneously optimize these two objectives:Signal-to-noise ratio (SNR)Received power
StrategyUse Strength Pareto Evolutionary Algorithm 2 (SPEA2) to find opti-mal LED layout settings
Formulationmaximize [ ( ), ( )]
( , , ). .
300 ( ) 1500
Tr
hor
P x SNR xx
x distance interval zenith Xs t
lx E x lx
where : average received power: average SNR: light intensity
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ConstraintsConstraints about LED layout setting
Other constraints are constant values of other system pa-rameters
0.5 1.5 ,
0.8 1.6 ,
0 50 .
m distance m
cm interval cm
zenith
Received power and SNR opti-mizationReceived power and SNR opti-mization
Parameter Value
Number of LED panels
Number of LED each panel
Size of LED panel
Transmitted optical power
Semi-angle at half power
Center luminous intensity
FOV at a receiver
Detector area in PD
Semi-angle at half power
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Result and discussion
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20
21
22
23
24
25
26
27
-1.5 -1 -0.5 0 0.5 1 1.5 2
SN
R [
dB]
Received Power [dBm]
Received power and SNR opti-mizationReceived power and SNR opti-mization
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Result and discussion
Link quality is determined by SNR. However, received power need to exceed some minimum threshold.Depending on system hardware, choose LED layout setting that gives just sufficient received power, but highest SNR.
Pr
[dBm]
SNR [dB]
Distance [m]
Interval [mm]
Zenith [deg]
-1.0670 26.5866 0.7 8 43
-0.4917 25.5346 0.7 8 40
0.0042 24.4159 0.7 8 36
0.4682 23.6270 0.6 8 26
0.9883 23.3149 0.5 8 5
1.4994 21.3524 0.8 8 9
1.6740 19.5300 1 9 0
Received power and SNR opti-mizationReceived power and SNR opti-mization
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ConclusionConclusionConclusion
There is trade-off between received power and SNR in VLC systemThe optimal link quality corresponding to the LED layout that gives just sufficient received power, but highest SNR.Using multi-objective optimization, we can find such op-timal LED layout setting.