From Tuesday 8th to Friday 9th, I attended the 1st Global LiFi Congress that took place in the prestigious and spacious Palais Brongniart in Paris.
Under the « haut patronage » of the president of the French republic Mr Macron (and the snow), this event supported by the IEEE, aimed to gather in the same place the scientific community, industrials and collectivities involved in Visible Light Communications (VLC) and Light Fidelity, also known as LiFi.
During these 2 days, visitors could attend academic conferences, keynotes and round tables, visit about 30 exhibitors booths set-up in the beautiful Nef of the building, or engage scientific discussions around twenty academic posters.
I take this opportunity to write a post about the so interesting topic that VLC is.
I’ll start introducing what are the main differences between LiFi and VLC, and then discuss some misconceptions. I will follow presenting the latest innovations in the field reviewing ready to market products before concluding introducing relevant works that the researchers are baking in their lab.
Common misconceptions about VLC and LiFi
LiFi is high data rate while VLC is low data rate
That is a misconception. According to this paper written by H. Haas, LiFi is a wireless communication technology that uses the infrared and visible light spectrum for high-speed data communication. LiFi, first introduced extends the concept of visible light communication (VLC) to achieve high speed, secure, bi-directional and fully networked wireless communications. It is important to note that LiFi supports user mobility and multi-user access. In short, LiFi extends VLC with the goal to provide internet access. VLC gathers a wider range of applications and use cases: localization, X-to-camera communication, vehicular communications that can be high speed too, etc.
With LiFi, there is no wave
I heard that during a keynote but that is false, even if I agree that it is a bit confusing as of the concept of light nature duality. In fact, our physics textbook says that you can either model light as an electromagnetic wave or you can model light a stream of photons.
Christian Huygens, who was a contemporary of Isaac Newton, suggested that light travels in waves. Isaac Newton, however, thought that light was composed of particles that were too small to detect individually. In 1801 a physicist in England, Thomas Young, performed an experiment that showed light behaves as a wave.
Remember that electromagnetic waves, including visible light, are made up of oscillating electric and magnetic fields.
The wavelength of electromagnetic radiation determines the color and all visible light has wavelengths between 400 and 700 nm. Electromagnetic radiation with shorter or longer wavelengths is not visible to humans, but it exists and can be detected. Not convinced? I suggest you read this article.
Today smartphone’s camera can be used for high-speed LiFi to provide internet
That is a remark visitors made when I was presenting our poster. No, today smartphone camera cannot receive LiFi to provide high-speed internet. The technology presented as “LiFi” that relies on the smartphone camera, for instance in a museum or by the streetlights in the Palaiseau city, just broadcasts an ID. So, it is wrong to call it LiFi or geoLiFi.
This ID that can be either received by the camera or a dongle is decoded in an application that, then downloads a corresponding video or localized content (news, advertising, …) through WiFi or Cellular network.
LiFi is 100x faster than Wifi
In any case, not today! The most performant products in the market (PureLiFi LIFI-XC) reach a data rate up to 50 Mbits that is lower than WiFi.
And with the 802.11ax WiFi standard that is coming in our AP and WiFi routers, I’m not sure that this is going to change soon…
Nonetheless, I agree that a VLC throughput higher than 10 Gbits has been recorded, in point-to-point conditions, in labs.
Today “LiFi” street lights provide internet
That is false, and as discussed few lines above, that is just a short ID that is broadcasted. That has been confirmed during Tuesday roundtables. One more time, the overuse of “LiFi” term makes this unclear.
Ready to market products
Let me now review some of the latest innovations and ready to market products. Notice that all of them target the professional market, and as Bernard Fontaine (Technological Innovations Director at France TV) said, they “can’t be bought at IKEA yet”.
Established in 2012, the Scottish spin-off of the University of Edinburgh co-founded by Pr. Harald Haas develops a LiFi high-speed, bi-directional, networked and mobile wireless communication system using the light spectrum.
They are selling LiFi-XC, a LiFi access point that provides high-speed (similar to Wifi) localized internet access to a laptop or a tablet equipped with a small dongle. The system relies on visible light for the downlink but infrared for the uplink.
Firstly announced in Paris at the Global LiFi Congress and much awaited, pureLiFi unfortunately cancelled their coming at the last minute.
The French startup founded by Pr. Suat TOPSU in 2012 offers solutions for indoor positioning system (GEOLiFi) and data communication (LiFiNET) through light, primarily for retail, and healthcare. They come at the Global LiFi Congress with their new desk lamp that in addition to lighting and decorating your desk is a LiFi AP. Today price is about 1k€ 🙂
Havr and LightBeeCorp smart lock systems
The first cited is a French startup founded while the second is a Spanish company established in 2014, but both are developing a wireless smart lock system. Using the smartphone flashlight and a photodiode hidden in the door lock, a user can unlock the door sending a unidirectional short light message (that they claim « uncrackable » without further explanations). The Canarian LightBeeCorp already has few early adopters, mostly hotel.
However, the lock developed by the French startup, called the “Havr Bright Lock” is still in development, and they just show a smartphone flashlight blinking and a traditional non-smart lock, to explain their concept.
Phillips Indoor Localisation system
The well-known market leader in LED lighting solutions proposes a combination of VLC technology, Bluetooth, and a smartphone’s inertial sensors to deliver indoor positioning that they claim accurate within 30cm, plus orientation, with in-pocket notifications, and analytics thanks to a cloud platform.
I conclude this section with Kiwink (yes, that is us :)), a bi-directional visible light communication technology for the IoT developed in 2016 by Rtone. Kiwink’s patented system makes any LED-equipped product able to communicate and enables it to send information to any smartphone.
During the Global LiFi Congress, I presented an academic poster that introduces few insights into Kiwink technology. It results from a collaboration between Rtone and the CITI Labs of INSA de Lyon. The full paper co-authored with Razvan Stanica, Hervé Rivano (CITI Lab) and Adrien Desportes (Rtone CEO) has been published in the conference proceedings.
You can go to our website if you want more information about Kiwink.
In the labs
I conclude this post by highlighting some academic works presented at the posters exhibition and during the academic conferences.
High-speed point to point VLC
Fraunhofer is developing a technology to create a point-to-point gigabits communication link at a distance up to 30 meters. They exhibited a prototype at their booth.
V2X and platooning VLC
Vehicular communication was the central motivation to the standardization of VLC in 2007. However, more than ten years later, vehicular communication with VLC is not yet a reality while many research groups are working in this field.
Bastien Bechadergue from the LISV, UVSQY, a pioneer university in the field, studied the use of VLC for platooning applications and presented his results in a poster. The experimental evaluation shows that a range of 30m can be reached with latency as small as 20ms. Thus, VLC is a good complementary solution to radio for V2V communication to avoid the 802.11p interferences and delay issues.
Integration with WiFi or 5G
The integration of VLC/LiFi in the existing communication networks, to make it transparent to users, is one of the blockers to broad adoption of VLC and LiFi.
Also, making that happen raises a lot of issues and challenges that remain unsolved yet.
Hopefully, researchers are working actively to reach this goal. During the poster exhibition, preliminary work by the ISEP and ERESCOM introduces the integration of VLC combined with mm-Waves in a 5G architecture. This work is supported by the EU within the H2020 Internet of Radio Light project that gathers universities and companies such as ISEP, ERESCOM or Oledcomm.
Body Sensor Network for medical application
At the XLIM laboratory (University of Limoges), the group headed by A. Julien-Vergonjanne’s is studying VLC and Infrared communications for medical Body Sensor Network use cases.
The poster introduces the main concepts of their idea: on-body sensors communicate to a remote medical monitoring system thanks to an IR emitter and a VLC receiver worn by the patient. By proposing a channel model and simulation evaluation, the authors conclude the combination of VLC/IR is promising in this context where exposition to radio waves should be avoided.
This first Global LiFi Congress finally ended Friday evening with the traditional “closing keynote”. I can’t say yet if it was a success or not but gathering the academic and industrial world in the same place was clearly a good idea.
However, I was a bit confused by the lack of technical and scientific discussions I was able to engage. I suppose that it is because most of the attendees were not specialists and often just interested in the technology or wanted to gain knowledge about “LiFi” and its market.
In the same way, the lack of technical staff on the exhibition space sometimes lead to unclear explanations or erroneous discourse, which I find too bad.
Doctorant au laboratoire CITI et ingénieur R&D en développement logiciel embarqué, Alexis effectue sa thèse sur le Visible Light Communication. Il est aussi passionné par l’Open Source. Voir son profil.