IEEE Consumer Electronics Magazine - July 2018 - 61

numofGen. Popsize represents the population size of fireflies
(i.e., number of controllers), and numofGen indicates the number of generations (i.e., number of iterations). In each iteration, we compare the brightness of firefly Fbest with the
brightness of all of the fireflies in the given population using
the FindAttractiveness () function, which gives the brightness
of the input firefly. If the brightness of firefly Fbest is greater
than the brightness of firefly Fi, then firefly Fi will be moved
toward firefly Fbest in D-dimension. Here, moving firefly Fi
toward firefly Fbest means that we will choose the D neighbor controllers of controller Fbest, with dimension D signifying the number of new controllers. If there is no brightest
firefly compared to firefly Fbest, then firefly Fi will be moved
randomly in D-dimension (i.e., we will choose D random
new controller). At the end of each generation, we will sort
all of the fireflies based on their brightness and select the
top N fireflies for the next iteration. We will repeat the process up to the number of generations and return the N best
possible chosen list of fireflies (i.e., list of controllers).

ExPEriMEntal analysis
To evaluate the effectiveness of our proposed DistArchSCNet model, we performed simulation and analysis in different phases.

mODuLatiOn sCheme PerFOrmanCe evaLuatiOn
To evaluate the performance of the modulation scheme for
Li-Fi communication in an indoor environment, the transmission is carried out by five transceivers, each of which consists
of 600 RGB LEDs. Table 1 shows the list of parameters that
we considered in assessing the effectiveness of the proposed
modulation scheme. We analyzed the distribution of illumination in the indoor environment since it is necessary for providing sufficient illumination in the Li-Fi communication
system in an indoor environment.
Figure 3(a) demonstrates the dispersion of light in the
indoor environment, with each RGB LED having emission

Table 1. A list of simulation parameters.
Parameters

Value

Area of indoor room

10 m # 10 m # 4 m

Receiver position

3.5 m from the ceiling or 0.5 m
above the floor

Transceiver location

{1.5 m, 1.5 m, 4 m}, {4.5 m, 1.5 m,
4 m}, {1.5 m, 4.5 m, 4 m}, {3 m,
3 m, 4 m}, {4.5 m, 4.5 m, 4 m}

Emission power of an
RGB LED

60 mW

Field of view at a receiver

75c

{ Semi-angle of an LED
with half power

75c

Number of RGB LEDs at
each transceiver

600

I ^U h [[16] illumination
at the center

9,000 mcd

Area of photodiode

1 cm2

power of 60 mW. As per the standard for typical indoor environments [16], the entire indoor area is provided with illumination of 900 ~ 12,00 lx. Based on the indoor environment,
we need to adjust the parameters' values in Table 1.
We measured the bit error rate performance to evaluate
the transmission link quality of our proposed hybrid modulation scheme. Figure 3(b) shows the result of the experiment on the proposed scheme and comparison with the
orthogonal frequency-division multiplexing (OFDM) and
on-off keying (OOK) modulation schemes. We can, therefore, deduce that the hybrid modulation scheme performs
better than the OFDM and OOK modulation schemes and
offers significant performance.

100
10-1
10-2

1,200
1,000
900

BER

Illuminance (Ix)

1,100

800

10-3
10-4
10-5
10-6

700

10-7

600

10-8
10-9
10-10

500

-4

-2

0
X (m)

0 -2
Y (m)

-4

OFDM
OOK
Proposed Scheme
0

6
8
SNR (dB)
(b)

(a)

figurE 3. The performance of a modulation scheme as seen by (a) the dispersion of light in the indoor environment and (b) a BER distribution in the indoor environment.

july 2018

IEEE Consumer Electronics Magazine

Table of Contents for the Digital Edition of IEEE Consumer Electronics Magazine - July 2018