Li-fi faster than everything & the most exciting technologies

What is Li-Fi?

LiFi provides a completely new layer of wireless connectivity within existing heterogeneous radio frequency (RF) wireless networks. LiFi supports multiuser access and enables roaming. It is, therefore, a truly mobile system. Multisuer access and mobility support in LiFi require unique building blocks as outlined in the figure below.  Techniques developed for RF systems cannot be applied direct as the signal propagation and information encoding techniques are different. However, the differences diminish as higher frequencies in RF are used such as mm wave bands. The paper also describes the first LiFi transmitter and receiver ASICs (application specific integrated circuits) developed at the University of Edinburgh as part of the UP-VLC project. These ASICs allow real-time data transmission of 1 Gbps as well as support multiple-input-multiple-output (MIMO) operation and wavelength division multiplexing (WDM). LiFi fulfils many key performance indicators (KPI) postulated for 5G systems.This paper attempts to clarify the difference between visible light communication (VLC) and light-fidelity (LiFi). In particular, it will show how LiFi takes VLC further by using light emitting diodes (LEDs) to realise fully networked wireless systems. Synergies are harnessed as luminaries become LiFi attocells resulting in enhanced wireless capacity providing the necessary connectivity to realise the Internet-of-Things, and contributing to the key performance indicators for the fifth generation of cellular systems (5G) and beyond. It covers all of the key research areas from LiFi components to hybrid LiFi/wireless fidelity networks to illustrate that LiFi attocells are not a theoretical concept any more, but at the point of real-world deployment.

How fast can LiFi be?

LiFi could transmit up to 100 Gbps and possibly higher, but this would require a change in lighting technology.Recent news report that LiFi is 100 times faster than WiFi. The assumption was that the average WiFi speeds are 10 Mbps, and that LiFi can be as fast as 1 Gbps. It is important to highlight that 1 Gbps transmission speeds from an off-the-shelf commercial LED light bulb have not been demonstrated, yet. In this discussion, it is important to compare like-for-like. The facts are:

• The visible light spectrum is 1,000 times larger than the entire 300 GHz of radio, micro wave and mm wave radio spectrum, so there is a big untapped reservoir of resources for wireless systems.

• The current and future growth of wireless data traffic will mean that the radio frequency spectrum will not provide sufficient resources by 2025.

• Phosophor coated white LEDs which are mostly used in all commercial lighting devices can deliver up to about 100 Mbps

• More expensive red, green, blue (RGB) LEDs can deliver up to about 5 Gbps, and allow control of colour.

• Laser based white LEDs with a diffuser to create a broad light beam could transmit up to 100 Gbps .

• The fastest WiFi in the 60 GHz frequency band, WiGig, can achieve a maximum data rate of 7 Gbps

• The experienced data rate in a network where multiple users must share the bandwidth is significantly lower than the maximum headline data rate in WiFi systems.

Therefore, a more important metric is the data rate per square meter, or area data rate.The area data rate of a LiFi network can be 1,000 times higher than the area data rate of a WiFi network. Please download this paper if you want to see the science behind this: ECOC 2015, invited. The main reason for this massive improvement is that, while there can only be one WiFi router in a room as interference would destroy the bandwidth, there can be tens and more light bulbs in a room as interference behaves entirely different when using light to carry data.