Visible light communication

1. Khulna University of Engineering & Technology
Visible Light Communication:
Opportunities, Challenges and
the path to market.
Written by:
Aleksandar Jovicic, Junyi Li, and
Tom Richardson
Presented by: Shuvo Raj Paul
Roll Number: 1003110
9/27/2014 1

2. Contents
 Introduction.
 Visible light & its spectrum.
 Motivation: Why visible light is used for communication
purpose?
 The VLC communication process based on intensity
modulation.
 LED modulation characteristics.
 VLC link capacity for typical office desk-level illumination.
 Integration with power line communication (PLC) for the VLC
downlink.
 Integration with the uplink technology such as Wi-Fi.
 Conclusion.
9/27/2014 2

3. What is
“Visible Light Communication” ?
The visible light communication (VLC)
refers to the communication technology
which utilizes the visible light source as a
signal transmitter, the air as a transmission
medium, and the appropriate photodiode as
a signal receiving component.
9/27/2014 3

4. Visible Light
Visible light is thus by definition comprised
of visually-perceivable electromagnetic waves.
The visible spectrum covers wave lengths
from 380 nm to 750 nm.
Visible Light Spectrum
9/27/2014 4

5. Why Visible light communication is needed ???
 The visible light spectrum is unlicensed & creates an
opportunity for low-cost broadband communication.
 VLC signals in adjacent rooms or apartment units would not
interfere with each other & data security is ensured.
 The front-end components of both transmitters and
receivers are relatively simple and cheap devices.
 The human eye cannot perceive the amplitude modulation
of light as long as the frequency of modulation is above the
so-called flicker fusion threshold.
9/27/2014 5

6. THE VLC COMMUNICATION PROCESS BASED ON
INTENSITY MODULATION
Fig-1: The VLC radio transmitter and receiver based on
intensity modulation/direct detection.
9/27/2014 6

7. LED MODULATION CHARACTERISTICS:
Fig-2: Frequency response of high-powered BRLUX-2670 LED &
BRLUX-560 LED.
9/27/2014 7

8. VLC link capacity for typical office desk-level illumination.
“Typical office desk-level
lighting is between 400 and
1000 lux. At 600 lux the
capacity of the link is around
150 Mb/s.”
Fig-3. VLC link capacity as a function of received illuminance
in lux. 600 lux is typical office desk-level illumination.
9/27/2014 8

9. INTEGRATION WITH POWER LINE
COMMUNICATION (plc) FOR THE VLC DOWNLINK.
“Since LEDs need a certain
DC voltage to turn on, they
can’t run directly off of the
60 Hz power cycle that’s
why bridge-rectifier or AC-to-
DC converter is used
inside their power supplies
that regulate the current
supplied to the LED.”
Fig-4: The modifications to the LED lamp or fixture that are required to
enable high data rate VLC signal transmission.
9/27/2014 9

10. INTEGRATION WITH THE UPLINK TECHNOLOGY
SUCH AS Wi-Fi.
Fig-5: The uplink can use an out-of-band technology such as
Wi-Fi. The Hy-Fi router manages the VLC downlink and Wi-Fi
uplink on a per user basis.
9/27/2014 10

11. CHALLENGES IN COMMERCIALIZATION
OF VLC.
Fig-6: Low Data Rate (LDR) Visible Light Communication that uses
simple, power-efficient ON-OFF signaling can be decoded by the
smartphone camera sensor.
9/27/2014 11

12. Conclusion
Visible light communication can supplement radio
frequency communication and improve wireless
network performance wherever short range links
are used such as in a home or office for downlink
Internet access or for device-to device file transfers
and video streaming. It requires no additional
hardware in mobile devices. this use case is the
most promising first step in the commercialization
of VLC.
9/27/2014 12

13. Thank you for
your
kind attention
9/27/2014 13