Lighting Matters: LiFi – Monthly Column featured in EE Publishers’ Vector Magazine

As I promised last month, we discuss the phenomenon of LiFi in this issue of Lighting Matters. LiFi is the brainchild of Dr Harald Haas, a professor at Edinburgh University’s Research Institute for Digital Communications.

LiFi uses the visible light spectrum to communicate via the internet. The current wireless frequency band is rapidly reaching its limit in terms of download speeds and data volumes, prompting Dr Haas to search for an alternative using higher frequencies with greater bandwidth. That search, in turn, led him to the visible light spectrum which has 10 000 times the frequency spectrum compared the radio frequency spectrum normally used for WiFi. While wireless will deliver coverage of about 32 m from the antenna, LiFi delivers coverage for about 10 m but it is possible to install several LiFi-equipped luminaires in offices or homes to increase the coverage. LiFi is intended to augment existing WiFi and not as a replacement.

LiFi does not “bleed”; it does not permeate walls, glass or buildings, thereby making it more secure than WiFi or Bluetooth. When you connect to a WiFi router, other networks are often visible but are sometimes secure and inaccessible. Non-secure connections (“free WiFi”) are, however, risky, making bank transactions undesirable due to security risks. Each device will require a LiFi dongle to enable the connected device to communicate with the LiFi-equipped luminaire. USB dongles and LiFi-equipped luminaires are already on sale in Europe. It is possible to use this system with only a single device without the need for a server. A USB dongle communicates via the LiFi light source, connected to a router.

Another feature is that up and download speeds are available from 1 GBPS to 100 GBPS. The luminaire does not have to be on; even a dimmed LED luminaire can provide LiFi.

The difference between Visible Light Communication (VLC) and LiFi is, simplistically, that VLC uses the ethernet to communicate via a gateway and hub via a router, whereas LiFi is independent of any other network.

In our next issue, I will discuss Indoor Positioning Systems (IPS) which will be introduced soon by large supermarket groups in South Africa.



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