2. 2
Outline
Chair for Measurement and Sensor Technology
Group 10
• Motivation – What and Why ?
• How it works ?
• VLC Realization using LTSpice Simlation
• Experimental Setup
• Test cases and Results
• Refrences
3. 3
What is Li-Fi? Why Li-Fi?
Chair for Measurement and Sensor Technology
Group 10
• Li-Fi : Light-Fidelity , Data transmission through illumination by LED that
varies intensity faster than a human eye can follow.
Prof. Harald Hass, www.ted.com
• Also known as VLC – Visible Light
Communication
• Data communication using LEDs / Visible light
• Standerd availabe – IEEE 802.15.7 [8]
Li-Fi Technology, www.techworld.com
• Coined the term „Li-Fi“ in 2011 in TED Global.
• One of the most influencing person in Li-Fi
technology
• Why do we need it?
• By 2020 – 50 Billion Devices connected to Internet wirelessly.
• Radio spectrum will run out of capacity.
• Huge available license free bandwidth. 430 THz to 790 THz.
• Very less extra device setup needed – Normal Illumination LED can be
used.
• About 100 time faster than Wi-Fi
• Data security
4. 4
How Visual light communication works?
Chair for Measurement and Sensor Technology
Group 10
• Light ON : Bit – 1
• Light OFF : Bit – 0
• Data rate depends on the type of data.
• Modulation methods available [2]
• Can flickering be Harmful?
• Flickering can be controlled – Not noticable by human eyes above 25 Hz.
• Frequency above 200 Hz is recommended.
The VLC radio transmitter and receiver based on intensity modulation/direct detection[1]
5. 5
Realization of VLC using LTSpice
Chair for Measurement and Sensor Technology
Group 10
The Simulation setup for VLC communication
• Input signal from a 3.5 mm
audio jack.
• DC offset through Vdc – Input
value above 0.
• If not given, -ve of input can
damage LED.
• Received signal
• Two amplification stage
• Both applies Gain of 50.
• Final signal compared to
the original input.
6. 6
Realization of VLC using LTSpice (Cont.)
Chair for Measurement and Sensor Technology
Group 10
Input Audio
Output Audio
Simulation results using LTSpice
dB
signalnoisepower
signalinputpower
SNR 39
)_(
)_(
log20
7. 7
Experimental setup using Arduino
Chair for Measurement and Sensor Technology
Group 10
VLC setup using two Arduino modules
(Transmitter located on Left side and
Receiver on right)
• Ardiono UNO modules
• 1 watt Blue LED
• Solar panel as receiver
VLC setup using two Arduino modules
8. 8
C code Flow
Chair for Measurement and Sensor Technology
Group 10
Receiver Code flowTransmitter Code flow
Data frame for Manchester Encoding
9. 9
Test Cases
Chair for Measurement and Sensor Technology
Group 10
Distance : 17 cm, Angle : 0 Degree
12. 12
Test Cases (Cont.)
Chair for Measurement and Sensor Technology
Group 10
• Best results came at the line of sight with 0 degree and 20 cm distance.
• Data rate of 500 bit/s.
• Using better configuration of devices, data rate can be increased
13. 13
References
Chair for Measurement and Sensor Technology
Group 10
[1] A. Jovicic, J. Li, and T. Richardson, “Visible light communication: Opportunities, challenges and the path to
market,” IEEE Communications Magazine, vol. 51, no. 12, pp. 26–32, 2013.
[2] S. Rajagopal, R. D. Roberts, and S. K. Lim, “IEEE 802.15.7 visible light communication: Modulation
Schemes
[3] H. Haas, L. Yin, Y. Wang, and C. Chen, “What is LiFi ?” Journal of Light ware Technology, vol. 34, no. 6, pp. 1533–1544,
2015
[4] S. Rajbhandari, H. Chun, G. Faulkner, K. Cameron, A. V. N. Jalajakumari, R. Henderson, D. Tsonev, M. Ijaz, Z. Chen, H.
Haas, E. Xie, J. J. D. McKendry, J. Herrnsdorf, E. Gu, M. D. Dawson, and D. O’Brien, “High-Speed Integrated Visible Light
Communication System: Device Constraints and Design Considerations,” IEEE Journal on Selected Areas in Communications,
vol. 33, no. 9, pp. 1750–1757, 2015.
[5] P. Pathak, X. Feng, P. Hu, and P. Mohapatra, “Visible Light Communication, Networking and Sensing: Potential and
Challenges,” IEEE Communications Surveys & Tutorials, vol. 17, no. c, pp. 1–1, 2015.
[6] A. Jovicic, J. Li, and T. Richardson, “Visible light communication: Opportunities, challenges and the path to market,” IEEE
Communications Magazine, vol. 51, no. 12, pp. 26–32, 2013.
[7] J. M. Kahn and J. R. Barry, “Wireless Infrared Communications,” Proc. IEEE, vol. 85, no. 2, Feb. 1997, pp. 265–98.
[8] IEEE Standard for Local and Metropolitan Area Networks-Part 15.7: Short-Range Wireless Optical Communication Using
Visible Light, IEEE Std. 802.15.7, Sep. 2011.
[9] www.arduino.cc