Light Fidelity (Lifi) - Page 1
Forum section: electronics / projects

author: swabaxter
author_rank: Newbie
timestamp: December 26, 2016, 07:56:32 am
content: Light Fidelity (Lifi)We all know about WiFi, a technology that uses Radio Waves for wireless communication and its available in mosthomes, offices and shopping centre. The technology is quite mature and at the same time we have Machine to Machine (M2M)and the Internet of Things (IoT) already a reality in many Industrial and Commercial environments.Professor Harald Haas (University of Edinburgh,Scotland) is leading in a new form of wireless communication called Light Fidelityor Lifi for short. This uses light instead of Radio waves to transmit the signal. Its been in development for 3 plus years and has beendemonstrated on TED and at IEEE events.I am now suggesting in light (no pun intended) of the developments that I have mentioned that the Infra Red spectrum be employed to deliverthe signal between nodes. This is a well proven technology that has been used for over 20 years, is secure and well supported. I aminterested to receive comments on my proposal and suggestions for prototype construction. The Arduino is already used in the EdinburghUniversity Labs but other similar platforms may be appropriate.

author: Rerouter
author_rank: Super Contributor
timestamp: December 26, 2016, 08:45:55 am
content: Infrared means the power level has to be low if the source is directional (cannot tell when staring directly into beam), which means your bandwidth will likely need to be reduced to handle the sudden fluctuations in mixed environments, e.g. a skylight above a roof fan, or a breeze blowing reflective louvers.As for how to do it on your own, its very simple, all you need is the equivalent of a TV remote RX (probably photodiode) and TX (bog standard IR LED), its how data is already sent in a reliable fashion by IR, the main difference is the baud rate and robustness of the link you need for your purposes.Main thing is its 100% not secure, anyone with a photodiode in the area can record both sides of the transaction, and would likely be broken in much the same way wifi is, by recording when the connection is esablished. and IR will happily pass through most peoples windows.

author: borjam
author_rank: Unknown
timestamp: December 26, 2016, 08:57:11 am
content: Quote from: Rerouter on December 26, 2016, 08:45:55 amNo wireless technology is secure by itself. Not even hardwired networks unless your cabling is really well secured, which is very difficult and expensive.That's what encryption was invented for

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 26, 2016, 03:56:44 pm
content: There actually was a project involved in running Ethernet over laser pointers, but it lost interest after Wifi became cheap on the open market.

author: borjam
author_rank: Unknown
timestamp: December 26, 2016, 05:59:13 pm
content: Quote from: NiHaoMike on December 26, 2016, 03:56:44 pmBack in 1990 there was a manufacturer of laser links called Terabeam. We used several of them in a campus and they worked.The things were expensive (like 6000 euro /unit) and the available bandwidth was 10 Mbps, a typical Ethernet.

author: timb
author_rank: Super Contributor
timestamp: December 26, 2016, 06:02:39 pm
content: Yeah, we had a infrared communication standard years ago, look up IRdA. Lots of laptops had ports, as well as PDAs. (Remember Palm Pilots and beaming?)Basically it shot RS-232 type serial data over an IR beam. In fact, a lot of UARTs you can still buy today support direct IR communications! In the early days it topped out at 115kbps, however there was a push up to around 1Mbit at the end which never really caught on due to Bluetooth and WiFi becoming popular.It was pretty poor technology, as the two systems had to be properly lined up and within inches of each other to maintain any sort of decent data rate.Good riddance I say.

author: rob77
author_rank: Super Contributor
timestamp: December 26, 2016, 06:14:42 pm
content: Quote from: NiHaoMike on December 26, 2016, 03:56:44 pmback in the days RONJA was quite popular over herefor those who never heard of RONJA:https://en.wikipedia.org/wiki/RONJA

author: madires
author_rank: Super Contributor
timestamp: December 26, 2016, 07:12:58 pm
content: There's a whole industry around FSO (Free Space Optics) selling you PtP laser links up to about 2.5 Gbit/s (STM-16) over several kilometers.