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Li-Fi: Light Fidelity Wireless Cheat Sheet (DRAFT) by [deleted]

Li-Fi emerging new WiFi-like technology

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Introd­uction - How Does It Work

When a constant current is applied to an LED light bulb a constant stream of photons are emitted from the bulb which is observed as visible light. If the current is varied slowly the output intensity of the light dims up and down. Because LED bulbs are semi-c­ond­uctor devices, the current, and hence the optical output, can be modulated at extremely high speeds which can be detected by a photo-­det­ector device and converted back to electrical current. The intensity modulation is imperc­eptible to the human eye, and thus commun­ication is just as seamless as RF. Using this technique, high speed inform­ation can be transm­itted from an LED light bulb.


Li-Fi features include benefits to the capacity, energy effici­ency, safety and security of a wireless system with a number of key benefits over Wi-Fi but is inherently a comple­mentary techno­logy.

LiFi vs WiFi


Low cost: Requires fewer components than radio techno­logy.
Energy: LED illumi­nation is already efficient and the data transm­ission requires negligible additional power.
Enviro­nment: RF transm­ission and propag­ation in water is extremely difficult but Li-Fi works well in this enviro­nment.



Bandwidth: The visible light spectrum is plentiful (10,000 more than RF spectrum), unlicensed and free to use.
Data density: Li-Fi can acheive about 1000 times the data density of Wi-Fi because visible light can be well contained in a tight illumi­nation area whereas RF tends to spread out and cause interf­erence.
High speed: Very high data rates can be achieved due to low interf­erence, high device bandwidths and high intensity optical output.
Planning: Capacity planning is simple since there tends to be illumi­nation infras­tru­cture where people wish to commun­icate, and good signal strength can literally be seen.


Safe: Life has evolved through exposure to visible light. There are no known safety or health concerns for this techno­logy.
Non-ha­zar­dous: The transm­ission of light avoids the use of radio freque­ncies which can danger­ously interfere with electronic circuitry in certain enviro­nments.


Contai­nment: It is difficult to eavesdrop on Li-Fi signals since the signal is confined to a closely defined illumi­nation area and will not travel through walls.
Control: Data may be directed from one device to another and the user can see where the data is going; there is no need for additional security such as pairing for RF interc­onn­ections such as Bluetooth.