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Visible Light Communication: Opportunities, Challenges and the path to market.

Written by:

Aleksandar Jovicic, Junyi Li, and Tom Richardson

Presented by: Shuvo Raj PaulRoll Number: 1003110

Khulna University of Engineering & Technology

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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.

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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.

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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

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

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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.

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THE VLC COMMUNICATION PROCESS BASED ON INTENSITY

MODULATION

Fig-1: The VLC radio transmitter and receiver based on intensity modulation/direct detection.

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LED MODULATION CHARACTERISTICS:

Fig-2: Frequency response of high-powered BRLUX-2670 LED & BRLUX-560 LED.

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Fig-3. VLC link capacity as a function of received illuminance in lux. 600 lux is typical office desk-level illumination.

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.”

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INTEGRATION WITH POWER LINECOMMUNICATION (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 toenable high data rate VLC signal transmission.

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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.

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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.

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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.

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Thank you for your

kind attention