The use of light as a means to transmit data has been coined Li-Fi (Light – Fidelity). The high-speed communication technology is similar to Wi-Fi but is faster, allowing you to send and receive more data in less time.

1. DESIGN AND CONSTRUCTION OFA DATA
TRANSMISSION SYSTEM USING LI-FI TECHNOLOGY
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PRESENTED BY:
OWOLABI YUSSUF KEHINDE (13/30GC124)
IFADA EMMANUEL (13/30GC070)
UNIVERSITY OF ILORIN
FACULTY OF ENGINEERING & TECHNOLOGY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
SUPERVISED BY:
DR. (MRS.) N.T. SURAJUDEEN – BAKINDE
ENGR. O.S. ZAKARIYYA
19TH JULY, 2018

2. PRESENTATION OUTLINE
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 Introduction/Background Information
 Problem Statement
 Aim and Objectives of the project
 Scope of the Project
 Methodology
 Results and Discussion
 Conclusion & Recommendations

3. INTRODUCTION/BACKGROUND INFORMATION
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 The use of light as a means to transmit data has been coined Li-Fi (Light –
Fidelity). The high-speed communication technology is similar to Wi-Fi but is faster,
allowing you to send and receive more data in less time.
 Light Fidelity (Li-Fi) is a high speed, wireless communication using visible light. It falls
under the category of optical wireless communications. Data transmission takes
place through Light Emitting Diode (LED) bulbs whose intensity varies. Based
on this variation, communication occurs digitally. This technology would have vast
applications where the use of Wi-Fi is limited or banned.
 The proposed project consists of three major parts, namely:
i. The transmitting device(PC),
ii. The Li-Fi trans receiver unit and
iii. The receiving device(PC)

4. PROBLEM STATEMENT
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This project circumvents the main problems mitigating and limiting effective
data transmission (i.e. capacity, efficiency, availability, and security) when
using the radio spectrum. Therefore, it would reduce the over – reliance on
Wireless – Fidelity (Wi-Fi) for data transmission.

5. AIM & OBJECTIVES OF THE PROJECT
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 To design the circuit diagram for the Transmitter and the Receiver in the system.
 To package the assembled components into a Li-Fi text transmission system.
 To test and analyze the Li-Fi text transmission system to ensure it meets the design
details.
The objectives of the project are as follows:
The aim of this project is to design and construct a data transmission system (made up
of the receiver and the transmitter) that transmits text data effectively using Li-Fi
technology.
Aim of the Project
Objectives of the Project

6. SCOPE OF THE PROJECT
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The proposed project would only be able to transmit text data using
Li-Fi technology but, the receiver (PC) would not be able to
transmit the text data back to the transmitter.

7. METHODOLOGY
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Figure 1 BLOCK DIAGRAM OF THE PROJECT
Transmitting Section
Receiving Section

8. METHODOLOGY CONT’D
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HARDWARE DESIGN
The hardware design section consists of the physical parts of the
project which are made up of the following circuit units;
 The Arduino Uno Board
 Photodiode
 Wavelength specific LED
 Resistors
 A transistor (in the transmitter circuit) and
 Low power Operational Amplifiers (in the receiver circuit)

9. METHODOLOGY CONT’D
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Figure 2 The Li-Fi transmitter and receiver circuit
Transmitter Circuit
Receiver Circuit

10. METHODOLOGY CONT’D
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In the Transmitter circuit :
Selecting a base resistance for the transistor (2N2222), 𝑹 𝑩 = 1 kΩ and
taking 𝑽 𝑩𝑬 = 0.7 V,
From the base loop,
𝑉𝐵𝐵 = 𝐼 𝐵 𝑅 𝐵 + 𝑉𝐵𝐸 (1)
𝐼 𝐵 = (𝑉𝐵𝐵 − 𝑉𝐵𝐸) / 𝑅 𝐵
= (5 – 0.7) V / 1 kΩ
= 0.43 mA
Thus, 𝐼 𝐶 = 𝛽 𝐷𝐶 𝐼 𝐵
= 10 x 0.43 mA
= 4.3 mA
To get the collector resistor: From the collector loop,
𝑉𝐶𝐸 = 𝑉𝐶𝐶 − 𝑉𝐿𝐸𝐷 − 𝐼 𝐶 𝑅 𝐶
(2)
Where 𝑉𝐶𝐸 = 0.3 V (from the data sheet) and 𝑉𝐿𝐸𝐷 = 0.7 𝑉,
The collector resistor is calculated as:
𝑅 𝐶 =
𝑉 𝐶𝐶 − 𝑉 𝐶𝐸− 𝑉 𝐿𝐸𝐷
𝐼 𝐶
(3)
= (5 – 0.3 – 0.7) V / 4.3 mA
= 93.023 Ω
𝑹 𝑪 ≈ 100 Ω (closest standard resistor value)

11. METHODOLOGY CONT’D
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In the receiver’s circuit:
The voltage gain of the non- inverting amplifier (LM358N) having its output
at Pin 1 is calculated as:
𝑨 𝑽 = 1 + 𝑹 𝟐/𝑹 𝟏 (1)
Since from the data sheet, the output signal from the photodiode is about
1.4V maximum and we desired to have an output voltage that would be
easily detected as a 1 signal when bit ‘1’ is sent, the amplifier is designed to
have a dc voltage gain of 3.
Setting the feedback resistor, 𝑅2, to be 8.2 kΩ; using equation 1, 𝑅1 is
calculated to be :
𝑅1 = 𝑅2 / (𝐴 𝑉 – 1)
= 8.2 kΩ / (3 – 1)
= 4.1 kΩ
𝑹 𝟏 ≈ 4.7 kΩ ( next closest standard resistor value)

12. RESULT
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Testing of
Circuit on
Breadboard
This Code
Encodes the
message in bits
and shows it on
the monitor

13. RESULT
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 The text data was transmitted and received at a very high
speed.
Encoding
and
Decoding
Monitor on
Computer 1

14. RESULT
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Interface of the
Receiver Circuit
Received
Message from
PC 1Port Status

15. CONCLUSION
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 The Li-Fi transreceiver device is a major step towards improved,
efficient, and secured data transmission.