(IJACSA) International Journal of Advanced Computer Science and Applications,
Vol. 8, No. 7, 2017
Analysis of Received Power Characteristics of
Commercial Photodiodes in Indoor Los Channel
Visible Light Communication
Syifaul Fuada1, Angga Pratama Putra2, Trio Adiono3
1,2,3
University Center of Excellence on Microelectronics, Institut Teknologi Bandung
PAU Building 4th floor, Tamansari street No.126, Bandung city, West Java, ZIP 40132
INDONESIA
Abstract—To date, the photodiode still the first choice
component is used in optical communication, especially for
visible light communication (VLC) system. It has advantages of
speed, energy consumption, and sensitivity, compared to other
devices (e.g. image sensor). There are many practical
implementations of high-speed VLC which uses photodiode.
Commercially available photodiode typically have specific
characteristics, so that it needs some consideration to be used as
optimal receiver devices in VLC system. In this paper, analysis of
received power characteristics of the photodiode in indoor lineof-sight (LoS) channel of VLC system is discussed. MATLAB®
simulation is used as approach model (student version). The
experiments are done by changing several parameters such as the
semi-angle half power of the transmitter, distance from the
transmitter to receiver, room size, field-of-view (FOV), lens index
and optical filter gain. From the results, it can be known that
distance, room size, FOV and LED power factor to have linear
characteristic against the received power of commercial
photodiode. Also in LoS channel model, the gain of optical filter
and lens index plays an important role in defining the
characteristics of received power.
Keywords—Commercial photodiodes; LoS channel; power
received; visible light communication
I.
INTRODUCTION
In recent decades, many researchers are interested in
research of Visible Light Communication (VLC) for various
application, such as vehicle to vehicle communication, Light
Fidelity (Li-Fi), hospitals data communication, real-time audio
& video transmission, underwater communication, space
communication, localization based movable devices (mobile
robot or autonomous robot), WLANs, visible light ID system
and so on.
There are many research about comparative study in VLC
system that is interesting to be discussed to gain deeper
understanding to develop VLC system, such as different
modulation technique in VLC system [1], comparison study of
OFDM multiplexing schemes (DCO, ACO, ADO) [2],
placement optimization of LED-array as emitter [3], available
bandwidth through red, green and blue phosphor LED [4],
effect of color filter in VLC physical layer system using mica
paper [5]-[6], noise analysis using variety Op-Amp and
photodiode for VLC system [7]-[8], single versus multicarrier
performance analysis [9], performance comparison using
variety QAM modulation from 4 to 512 based RGB LED [10],
analysis of different LED array spacing [11], VLC system
performance within and without analog filters [12], decoder
performance within and without Viterbi [13], and so on.
Photodiode is a common photodetector device that can be
used for precision measurement or optical communication
application, e.g. VLC, fiber optic and infrared communication.
Compared with other devices, such as the light dependent
resistor (LDR), photo-IC, solar cell and phototransistor, The
photodiode has several advantages in stability, precision and
response time. The commercial photodiode can be divided
into several types, those are: 1) precision photodiode that can
be properly used for light measurement; 2) high-speed
photodiode that has general characteristic of high cut-off
frequency, which is suitable for optical application; or
3) integrated photodiode such as S8475 and S9295,
manufactured by HAMAMATSU®, which already integrated
with pre-amp in a single chip. Each type of photodiode has its
own advantages and disadvantages.
There are various studies about the comparison of
photodiode types for application of optical communication.
The photodiode selection is important in communication
system because it can affect sensitivity, speed, range,
reliability, cost, and another factor in the communication
system. Research scheme of photodiode types already been
done by A. Boudkhil, et al. [14] who compares noise
performances of PIN and APD photodiodes through an optical
high debit transmission chain. Then P. Sharma, et al [15]
compares PIN and APD performances with different
modulation and wavelength of LED transmitter. Also M.A.A
Ali [16] analyze APD performances for underwater
communication application through combination scheme of
the Jerlov water variable types (I, IA, IB) and photodiode
material types (Si, Ge, InGaAs). Then O. Kharraz and D.
Forsyth [17] analyze optical excess noise and thermal noise
which exist in PIN and APD. Then Y. Chen, et al [18]
experiment about optimizing collimating lens of the
photodetector for supporting long range VLC. The author
himself already done the investigation on capacitor junction
(Cj) effect on total noise, which is an RMS function of voltage
noise, current noise and feedback resistor in discrete TIA
circuit [19]. All of the above six experiments are done through
analytical calculus approach and proven by MATLAB® and
other specific simulator tools.
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(IJACSA) International Journal of Advanced Computer Science and Applications,
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The VLC system can be divided into three main parts,
transmitter, channel and receiver. Channel in VLC system is a
free space which can be implemented as Line-of-Sight (LoS)
and Non-Line-of-Sight (NLoS) link. In LoS, one of its weak
points is on shadowing effect which is caused by object
blocking, such as by household equipment or human activities.
Another LoS weak point is its limited covering area capability,
so it's incapable of supporting mobile user because the LoS
configuration requires transmitter and receiver to be placed in
a straight line. The solution of this problem is by using
photodiode which has broad FOV characteristic. Besides that,
the LoS advantage is on its characteristic that can support
high-speed data transfer for a relatively long distance and its
invulnerability of distortion from multipath signal induction
and ambient light noise. Illustration of the LoS link is shown
in Fig. 1(a), in which photodiode as receiver placed on a
straight line from LED. This link angular distribution is shown
in Fig. 1(b). The mathematical derivation of the LoS link is
explained in Section III of this paper.
The light information which transmitted from the LED will
be weakened (fading) while transmitted on the free space
channel, it means the farther the distance of the receiver, the
weaker the signal received, and the information may not be
received at all [20]. For that problem, the solution is to
increase the LED power or to add more LED as the
transmitter. But this is not the best solutions because it is not
power efficient. Besides, adding more LED will add another
problem, roaming. The ideal solution is by selecting the
proper photodiode and optimizing the photodiode filter.
The ideal photodiode characteristics can be found in the
datasheet from each manufacturer, where its specification can
be analyzed through finding the relations of LED power of the
VLC system with the received power in the photodiode (see
Section III). By using this method, we can accurately predict
the performance of the photodiode which will be implemented
in VLC system. Based on the observations from many works
of literature until this far, the discussion about photodiode‟s
received power characteristic of the different commercially
available photodiode is still rarely found. Related research has
been discussed by K. Lee, et al. [21] which analyzes the effect
of photodiode‟s received power with LoS and NLoS scenarios
with different wall type. Since this paper isn‟t exploring the
received power characteristic based on different photodiode
manufacturer, on this paper we will discuss that characteristic
of the photodiode based on different manufacturer. The
motivation of writing this paper is to fill that area of study.
Besides that, we also done other experiments that
observing the effect of changing several parameters of the LoS
channel against the received power on the photodiode, such as
1) changing semi-angle of the transmitter; 2) variating power
of a single LED; and 3) changing the distances of the channel.
After that, the effect of FOV, room dimension and internal
concentrator of the photodiode against its received power
characteristic will also be investigated. To find the ideal value
of this characteristics, these experiments using simulation
based approach using MATLAB® have been performed.
This paper is divided into several parts. The first part is an
overview of VLC system, research area, channel system,
problems and purpose of the experiments. The second part
explained the photodiode consideration and several types of
the photodiode. The third part explained the detail of the LoS
channel which has been introduced in the introduction part.
The fourth part discusses the experiment set-up, results, and
analysis. And the last part consisted of conclusion,
acknowledgment, and references.
II.
PHOTODIODE CONSIDERATIONS IN VLC SYSTEMS
Several considerations on selecting commercial
photodiode for VLC application is as follows: 1) surface area;
2) generated short current; 3) capabilities to detect
wavelength; 4) frequency cut-off; 5) rise-time; and 6) dark
current and internal capacitance/junction capacitor (Cj).
With broad surface area, for example, 10 mm x 10 mm, the
photodiodes can be used to support mobility in VLC system.
This sensing area capability can be improved by arranging the
photodiode in an array setup such as being done by J.H. Li, et
al. [22].
(a)
(b)
Fig. 1. (a) Geometry of LoS channel configuration in 3 m x 3 m x 3 m room; (b) MATLAB® simulation of light intensity distribution in room using LED with
characteristics of 30 Watt, d = 1 meter, FOV = 30o, number of transmitter = 1, number of grid = 25,
=
, and
=
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Although, the larger the area, the cut-off frequency will
become narrower and tend to be easily disturbed by the
ambient light noise. For the high-speed application, this
characteristic needs to be considered, to make the robust VLC
system design that has high tolerances characteristic with
noise from other light sources, such as sunlight.
After that, we also need to consider the short current. As
we all know, the photodiode will generate current with linear
characteristic against the light intensity, the brighter the light
intensity, the higher the current that will be generated, at least
around >100µA. The lower the short current, the higher the
gain of the Op-Amp, and it will affect on the narrower
bandwidth. The cut-off frequency (f-3dB) is inversely
proportionated with the division of Op-Amp Gain Bandwidth
Product (GBW) and voltage gain (Av). Another factor that
needs to be considered is the wavelengths that can still be
detected. On VLC application, the chosen the photodiode
needs to has capabilities to senses wavelength in visible light
spectrum range, i.e. 380 nm to 780 nm. Mistakes on the
selection of the phtodiode can affect the system to not be able
to work optimally.
A photodiode with high cut-off frequency (~GHz scale)
and fast rise time (~nanosecond scale) characteristics can be
used for high-speed optical communication, although typically
these characteristics have to trade off with the narrow sensing
area (around 0.1 mm), so while it supports high-speed data
transfer, it doesn‟t support the mobility of VLC system, and
the receiver needs to have 0° elevation angle. Even though, in
general, the VLC needs to able to provides mobility
characteristic. This problem has several solutions such as
using optic concentrator (collimator lens or polarizer) to
focusing the light into the photodiode, adding more
information light sources (for example, array LED based intercell system) or arranging the photodiode in an array based
setup.
The dark current is generated current from a photodiode
in a dark condition (no-light). The chosen PD needs to have
low dark current characteristic and also low the Cj. In previous
research, the lower the Cj, the higher the noise on the
photodiode and the slower the response of photodiode
amplifier. Both of these characteristics are important, and it
will affect noise on the photodiode which have strong
relations with en and in on the chosen Op- Amp [23].
All of those six factors above, can‟t be obtained
simultaneously. Commercially available photodiode, typically
only have one or two of those characteristics (no more than
three), thus the selection process must be thorough. These
limitations can be used as main consideration to create selfmade photodiode in a research based method, as been done by
H. Chen, et al. [24] and W. Zou, et al. [25].
TABLE I.
COMPARISON BETWEEN PIN AND APD IN VLC SYSTEM
Variable
Materials
Bandwidth
Life time
Spectral range
Form factor
Electromagnetic immunity
Magnetic field sensitivity
Large area
Gain
Operating Voltage (V)
Cost
Efficiency (A/W)
Response time
Sensing sensitivity
Temperature sensitivity
Bandwidth & bit rate
Damage by Stray light
Dark current
Excess noise factor
Mechanical Robustness
III.
PIN
APD
Si, Ge, InGaAs
To 40 GHz
OK
Tunable (Ultraviolet, Visible light, Near
Infra-red)
Small
No
No
No
1
102
Low
High
(0 - 5)
(100 -100k)
Low
High
Low
High
Fast
Slow
Low
High
Low
High
High
Medium
No
Yes
High
Low
Low
Medium
High
Medium
THE LOS CHANNELS DESCRIPTION
. As shown in Fig. 1(a), LED placed at height h relative at
region „x‟ and „y‟ from the receiver. LED radiation angle of
the transmitter to the receiver against transmitter normal,
denoted with . Whereas LED radiation angle to the receiver
against receiver normal, denoted with , where the receiver
has a FOV. LED radiation can only be sensed while on the
FOV range, where maximum angle range against the receiver
normal denoted with .
Fig. 1(b) shows the distribution of information light
intensity inside a room that has an uneven distribution. This
uneven distribution is shown with different color gradation in
several areas. The maximum power that can be received by
the photodiode on distances less than 250 cm is 1.4 to 1.2
dBm. Whereas, for distances, more than 500 cm, the power
that can be received by the photodiode is around 1 dBm. The
photodiode has three main part, those are: 1) the concentrator
(coating) to focusing light; 2) the filter for passing signals
only at a certain frequency range, or as band pass filter, so that
noise of ambient light can be reduced; and 3) the
photodetector to converts light into electrical currents.
Illustration of the photodiode parts is shown in Fig. 2.
In VLC practical demonstration, there are two types of the
photodiode that are of primary interest, i.e. Positive-IntrinsicNegative (PIN) and Avalanche photodiode (APD). The
characteristics of both of these photodiodes has been discussed
by M. Azadeh [26]. The comparison of PIN and APD is shown
in Table 1. These data are gathered from many work of
literature. To make it short, PIN provides higher sensitivity,
higher bandwidth, lower operating voltage and also cheaper.
Fig. 2. The photodiode configuration.
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Coating and filter have an effect on the received light on
the photodiode, the coating will yield different refractive
index of light which propagated from outside of the
photodiode, so light propagation direction is changed. This
phenomenon will be affecting the FOV of the receiver, as well
as an effective region of the receiver (
) which denoted as
), where n parameter is the refractive index of the
concentrator and
is the maximum angle of FOV on the
photodiode. The filter of photodiode is also affecting receiver
effective region, this factor is denoted as
.
{
Then it will be shown how coating and filter will affecting
. First is by ignoring the filter effect, concentrator effect,
and losses in reflection. The receiver will receive the light
radiation at an effective area which can be written
mathematically as (2), where Ar is the surface area of the
photodiode. Then by adding parameter of coating factor,
)
and filter factor
. The
can be expressed as (3).
{
{
For the relationship between optical power transmitted by
LED and received by the LED. In this case, the frequency
response of the transmitted and received visible light is flat
enough and can be denoted as DC gain (
). Thus, the
relations between optical received power (Pr) in watt and
optical transmitted power (Pt) could be expressed as (4).
Where,
Where,
is radiant Lambertian, then could be
expressed as Eq. 6, is the angle irradiance form of the LED,
is the order of the Lambertian emission which defined by
LED‟s semi-angle at half power (
, where
.
The intensity of light received by the photodiode has a
dividing factor of the quadratic of the distance (
) of the
intensity transmitted by LED. Whereas, received power is a
product of received intensity against the effective area of the
can be
receiver. Therefore, optical received power
expressed as (7).
Where,
LOS is also equal to (8).
)
Variable denotes the distance between the LED and the
photodiode. By substituting (1), (2) and (5) to the (8), DC
channel gain function will be obtained (9). Where
is equal
to
.
{
According to calculation, it can be shown that (4) is a
and (1), then from (4), an 3D
multiplication of (9) with
model can be simulated by MATLAB® using parameters that
will be obtained in Section IV. To make the analysis become
easier, the unit of watt will be transformed into dBm through
(10). Another discussion about LoS channels of VLC can be
shown in [27]-[29].
IV.
DISCUSSION
A. Experiment Set-up
In this experiment, the photodiode manufactured by
OSRAM optoelectronics is used. From its datasheet, it can be
obtained information that has been explained in Section III.
There are five PIN type of photodiode that is used: BPW21,
BPW34B, BPX65, SFH213, SFH221. The detail is shown in
Table 2, where there are nine variables, i.e., the features of the
,
, λ, and . While
photodiode, ,
, ,
,
parameters for simulation experiment is shown in Table 3,
where there are three scenarios of simulation. Variable
in
this experiment is used as static variable because this variable
is an intrinsic variable of the photodiode and can‟t be changed.
Based on the recommendation from [30], for an indoor
application (assumed dimension of 3 m x 3 m x 3 m)
minimum lumen requirement is around 250 to 500 lm/m2.
Based on that information, LED that is capable of works in
that lumen range and has a maximum power of 5 Watt is
chosen. The chosen LED is CREE XLamp® XT-E LE which
has maximum ~629 lm and configured in parallel so its
maximum power is 50 Watt.
The receiver devices is placed at the distances of 3 meters
from the information source, and the LED placed on the
coordinat (1.5, 1.5, 3), or exactly at the middle of the room.
Because in this experiment is use the LoS channel, the
reflectivity of the wall can be ignored. In the datasheet, the
gain filter and the concentrator is not specified, so these also
ignored. The effect of changing transmitter‟s placement
coordinate is not addressed in this paper because in this
calculation only use a single LED which has been explored
before on [11] and [31]. Since the price of the photodiode was
changed in every time, the cost factor is not use in product
comparison.
On the scenario A, B, and C, (9) is used to be computed in
MATLAB®, however in the datasheet of each photodiode,
is not specified, so calculation
parameters
references will be based on (9) and (10).
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TABLE II.
PHOTODIODE SPECIFICATION
Variable
Notation
BPW21
BPW 34B
BPX 65
SFH 213
SFH 221
Features
-
Si PD for the Visible
Spectral Range
Si PD with Enhanced
Blue Sensitivity
Si PIN PD
Si PIN PD
Si Dual PD
7.45
7.45
1
1
1.54
350 – 820
350 – 1100
350 – 1100
400 – 1100
400 – 1100
10
7.4
10
125
24
580
55
10
72
60
75
11
40
10
11
10
-
25
55
24
250
150
250
150
50
TABLE III.
EXPERIMENTAL PARAMETERS
Physical area of photo-detector (
Spectral response range (
λ
)
Short circuit current at 100 lux (
Terminal Capacitance (
Half angle (o)
Gain of optical filter
Spectral sensitivity (
Total power dissipation (
)
)
)
S
)
)
Variable
Notation
Room dimension
x x
Scenario A
Scenario B
Scenario C
3m x 3m x 3m
Transmitter coordinator
-
Center (1.5, 1.5, 3)
Number of Transmitter
-
Single LED
Reflectivity of wall
γ
ignored
PD concentrator refractive index
n
ignored
Gain of optical filter
ignored
Field of view (FOV) semi angle of the receivers
Sesuai kemampuan PD
Transmitter‟s semi-angle at half power
15o, 30o, 45o, 60o,
75o, 90o
45o
0.5m, 1 m, 1.5m, 2 m, 2.5m, 3m
Distance between LED and PD
d
2m
Maximum optical power of LED
PLED
50 W
2m
5W, 10W, 20W, 30W, 40W, 50W
B. Scenario I
In this scenario, transmitter‟s angle is a function of
received power. Settings of this scenario are
= capability
of the photodiode, where this parameter can be found in
Table 2. The channel distance is fixed, i.e. 2 meters, with
transmitter power 50 Watt and
is changed from minimal
o
o
15 and maximum 90 with range difference of 15°. The result
of the simulation is shown in Fig. 3.
From that figure, it can be known that the larger
, the
smaller received power in the photodiode. This is matched
with the characteristic of the LoS channel, where the received
power will be larger if the deviation angle of the receiver from
the transmitter is closer to 0°.
BPX65 and SFH213 have similarities in physical area, the
same with BPX65 and SFH213. Even though there are
differences in FOV, the received power is relatively the same
if semi-angle half power is changed. This is because
and the refractive index of the lens (n) are not included in the
calculation.
Fig. 3. Semi-angle half power of the transmitter vs photodiode‟s received
power.
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Fig. 4. Distance vs photodiode‟s received power.
Fig. 6. FOV vs photodiode‟s received power.
The result of this simulation is shown in Fig. 4, where it
can be known that the further the distance, the smaller the
received power at the photodiode. It is because of the
characteristic of the channel LoS, where the closer the
transmitter to the photodiode, the higher the intensity of light
that is received by the photodiode.
D. FOV of the Photodiode
As has been addressed on the background, on this paper,
the authors are also interested to find the effect of difference
photodiode‟s Semi-angle Half power FOV against the received
power. The parameter of this simulation is shown in Table 2,
with
= 30°, LED power = 50 Watt, d = 2 meters. The
photodiode is chosen with large semi-angle characteristic, that
is BPW34B ( = 1 mm2), then the value of
will be
variated, from 55, 60, 65, 70, 75 to 80. Then the value of
= 1 and n = 1. The result of this simulation is shown in
Fig. 6 and it shows the characteristic of FOV on the
photodiode is affecting the received power, although
insignificantly. Therefore, even though insignificant, the value
of FOV can be used as consideration in choosing photodiode
for VLC application.
Short current is the current which generated by the
photodiode that is linear with light intensity. But, the smaller
the variable d. Therefore, to simulate the real condition, the
minimum distance should be 1 meter.
C. Scenario III
In this scenario, the effect of changing the LED power is
observed. The parameters of this simulation is as follows: 1) d
= 2 meters, this is the fixed distance of LED to photodiode,
and LED to the object (e.g. Table 2), it means the height of the
object is assumed to be 1 meter, 2)
of 45° and transmitter
power variated from 10 Watt, 20 Watt, 30 Watt, 40 Watt and
50 Watt. On the implementation, power setting can be done by
configuring the forward voltage ( ) of the LED. The larger
the , the larger the power. The result of this simulation is
shown in Fig. 5, where LED power is linear with the received
power at the photodiode.
E. Effect of Changing Room Size
The purpose of this experiment is to prove that “the
dimension of the room is linier with the received power”. This
experiment use photodiode BPW 34B with
= 7.45 mm2,
o
= 45 , and LED power = 50 Watt. Fig. 7 shows the result
of the simulation from the side view with different room
variation as follow: a) 1 m x 1 m x 1 m with d = 1 meter, in
3D view; b) 2d view of (a); c) 3 m x 3 m x 3 m with d = 3
meters in 3 dimension view; d) 2 dimension view of (c); e) 5
m x 5 m x 5 m with d = 5 meters in 3D view; f) 2D view of
Fig. 7(e). The results show that the hypothesis is correct, that
the larger the dimension of the indoor room, the weaker the
intensity of light and the distribution of light can‟t reach small
sides in the room.
F. Effect of Changing Filter and Concentrator
It has been addressed in Section III that concentrator is a
part of the photodiode, even if on the datasheet (as shown in
and
are not specified. Because of that, in
Table 2),
this paper, will be investigated if the changes of both of those
variable affecting the photodiode significantly. On the
and
of the photodide is not
implementation, if on
available, the filter and the external concentrator can be added.
Fig. 5. LED power vs photodiode‟s received power.
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(a) The 3D view of Room size 1 m x 1 m x 1 m with d = 1 meter (Number
grid = 50)
(b) The 2D view of Room size 1 m x 1 m x 1 m with d = 1 meter
(Number grid = 50)
(c) The 3D view of Room size 3 m x 3 m x 3 m with d = 3 meters
(Number grid = 50)
(d) The 2D view of Room size 3 m x 3 m x 3 m with d = 3 meters
(Number grid = 50)
(e) The 3D view of Room size 5 m x 5 m x 5 m with d = 5 meters
(Number grid = 50)
(f) The 3D view of Room size 5 m x 5 m x 5 m with d = 5 meters
(Number grid = 50)
Fig. 7. (a) The 3D view of Room size 1 m x 1 m x 1 m with d = 1 meter (Number grid = 50), (b) The 2D view of Room size 1 m x 1 m x 1 m with d = 1 meter
(Number grid = 50), (c) The 3D view of Room size 3 m x 3 m x 3 m with d = 3 meters (Number grid = 50), (d) The 2D view of Room size 3 m x 3 m x 3 m with d
= 3 meters (Number grid = 50), (e) The 3D view of Room size 5 m x 5 m x 5 m with d = 5 meters (Number grid = 50), (f) The 3D view of Room size 5 m x 5 m x
5 m with d = 5 meters (Number grid = 50).
For that, the simulation parameters are, the distance of the
photodiode to the LED of 2 meters,
= 1°, which is
perpendicular toward LED, transmitter power of 10 Watt (the
minimum value) and FOV = 45°. This experiment is done on
photodiode SFH 213 ( = 1 mm2).
Fig. 8 shows the simulation result with parameters setting
= 1 and refractive index of lens (n) = 0.5, 1, 1.5, 2 and
2.5, where the calculation of
is based on (1). Then,
Fig. 9 shows the simulation result with setting n = 1 and
= 1.5, 2, 2.5, 3, 3.5, and 4.
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[1]
[2]
[3]
[4]
[5]
Fig. 8. Lens index vs photodiode‟s received power.
[6]
[7]
[8]
[9]
[10]
Fig. 9. Optical filter gain vs photodiode‟s received power.
V.
[11]
CONCLUSION
The investigation of received power characteristic on
several commercially available photodiode for VLC system
with LoS channel has been done clearly. The results of this
research show that FOV is not affecting the received power
and n factor are ignored. This can be
characteristic if
seen from the result of Scenario I which is done by changing
the semi-angle of the transmitter. Then on Scenario II, which
is done by variating the LED power and Scenario III, by
variating the channel distances which denoted by d (meters).
and n factor plays
On the next scenario, it is known that
an important role to improve the received power at the
photodiode significantly.
Since this article is only investigated the LoS area, the
investigation of other channels (i.e. NLoS) is an interesting
topic for upcoming issues.
[12]
[13]
[14]
[15]
[16]
ACKNOWLEDGEMENT
The authors wish to acknowledge the “PUT-PT
Mikroelektronik” and also administrator at the IC design
laboratory, Institut Teknologi Bandung for their financial
support. We would also like to show our appreciation towards
the Institut Teknologi Bandung for providing us with the
MATLAB® student license to accomplish this work.
[17]
[18]
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APPENDIX
In this work, the MATLAB® computations are adopted from [32]. In
order to obtain specific point, the authors modify from 3D model to 2D model
and then analyze by viewing maximum point of curve characteristic (shown in
Fig. 10). A sample of the MATLAB® codes to calculate the LoS channel gain
of variety commercial photodiode based 2D view is shown in the program
below:
theta=45; %semi-angle at half power
m=-log10(2)/log10(cosd(theta)); %lambertian order of emission
P_total=50;%transmitted optical power by individual LED
Adet=1.54e-3; %detector physical area of a photodiode in cm
FOV=55*pi/180;%FOV at receiver
lx=3; ly=3; lz=3; %room dimension in meter
h=2; %the distance between source and receiver plane
XT=0; YT=0; %position of LED
Nx=lx*25; Ny=ly*25;%number of grid receiver plane
x=-lx/2:lx/Nx:lx/2;y=-ly/2:ly/Ny:ly/2;[XR,YR]=meshgrid(x,y);
%receiver plane grid
D1=sqrt((XR-XT(1,1)).^2+(YR-YT(1,1)).^2+h^2);
%distance vector from source 1
cosphi_A1=h./D1;
%angle vector
H_A1=(m+1)*Adet.*cosphi_A1.^(m+1)./((pi)*D1.^2);
%channel DC gain for source 1
P_rec=P_total.*H_A1;
%received power from source 1
P_rec_dBm=10*log10(P_rec);
plot(max(P_rec_dBm));
Fig. 10. The 2D view of maximum point of the photodiode‟s received power
at -17.36 dBm.
AUTHORS PROFILES
Syifaul Fuada received B. Ed degree on
Electrical Engineering Education major from State
University of Malang (UM), Indonesia in 2014/2015
and M. Sc degree on Microelectronics engineering
major, School of Electrical Engineering and
Informatics Institut Teknologi Bandung, Indonesia
in 2016/2017. Currently he is working in University
Center of Excellence on Microelectronics Institut
Teknologi Bandung. His research interests include Analog circuits design,
instrumentation system, circuit simulation, engineering education, multimedia
learning, game conceptor, and Visible Light Communication.
Angga Pratama Putra received his B. Sc. and
M.Cs degree in Electrical Engineering from Institut
Teknologi Bandung (ITB), Indonesia. His research
interests include Embedded System, Software
Engineering, VLSI, System-on-Chip, Internet of Things,
Digital Signal Processing (DSP) and Visible Light
Communication (VLC).
Trio Adiono obtained his Ph. D. degree in
VLSI Design from Tokyo Institute of Technology,
Japan, in 2002. Currently, he is a lecturer at the
School of Electrical Engineering and Informatics, a
Head of the Microelectronics Center and IC Design
Laboratory, ITB. He currently serves as a chair of
the IEEE SSCS Indonesia Chapter. His research
interests include VLSI, Signal and Image Processing, Visible Light
Communication, Smart Card, Electronics Solution Design and Integration.
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