In previous posts of this ‘What is’ series we looked at LPWAN technologies such as LoRaWAN and Sigfox. These are all forms of wireless Wide Area Network (WAN) protocols enabling IoT connectivity over longer ranges. In this post I introduce an emerging technology with a shorter range in the category of wireless local area networks (WLAN): LiFi. As explained in my IoT book Digitize or Die, wireless local area networks typically cover a range of about 100 to 1000 meters. In case you are new to the wireless technologies which are used for the Internet of Things (IoT) check out the image below for an overview. LiFi (also Li-Fi, short for Light Fidelity) is a wireless communication technology leveraging the intrinsic capacities of LEDs (light-emitting diodes) to enable data transmission at high speeds. It is often compared with Wi-Fi due to its overlaps and the fact that both are WLAN technologies. However, there are important differences between Wi-Fi and LiFi. The main one is that LiFi uses light instead of radio frequency to transmit data. iot-wireless-technology-internet-of-things-iot-book

LiFi: how does it work?

LiFi uses (visible) LED light for the downlink and infrared light for the uplink. LEDs are switched on and off a million times per second. It’s through this modulation that LiFi enables data transmission. LiFi technology is complementary to RF technologies such as Wi-Fi. Since light doesn’t travel through walls it is especially suited for specific use cases. These include use cases in, among others, smart buildings, critical facilities and industrial environments. LiFi is not a formal standard yet. However, end 2017 the IEEE (Institute of Electrical and Electronics Engineers) announced the formation of the IEEE 802.11 Light Communications Study Group which is working towards global standardization for light communications and LiFi. The standard will belong to the same family as Wi-Fi and other technologies: the IEEE 802.11 set of media access control and physical layer specifications for the implementation of wireless LAN communication (more about these layers in my article on the OSI reference model).

The usage and benefits of LiFi

Today, LiFi is already used in real-life smart building projects and applications where electromagnetic interference is not allowed or desired. Schneider Electric, the company I work at, has worked with its partners to realize the award-winning Ampère e+ building which is one of the first office buildings across the globe where LiFi is already in place. This was done in collaboration with visible light communications pioneer Lucibel who collaborates with pureLiFi, a company that was co-founded by Professor Harald Haas. At a 2011 TED Global Talk Harald Haas, who coined the term LiFi, introduced the idea of “wireless data from every light bulb”. In a white paper Lucibel defines LiFi as “a networked wireless communication technology transforming solid-state indoor lighting into a backbone for information”. It’s a recommended read in case you want to know everything about LiFi. It’s important to know that in buildings LiFi has an important role in energy efficiency, the usage of IoT and the powering of connected devices whereby it’s a great fit with PoE or Power over Ethernet. What role does LiFi play and why does it matter in a context of IoT?
  • LiFi is a perfect solution when you need connectivity in a zone where privacy and security are essential given the mentioned characteristics of light: it doesn’t travel through walls. In other words: the data ‘stays’ in a confined space.
  • In facilities or specific areas of facilities where radio waves are not allowed (some zones of hospitals, petrochemical or nuclear plants, facilities protected by regulations etc.) LiFi is the ideal alternative for Wi-Fi.
  • LiFi also helps solve congestion challenges in a time where ever more devices get connected. This can be the case in office buildings but also think about places where Wi-Fi networks typically don’t work well such as busy event locations.
On the level of IoT in facilities, LiFi is perfect because it uses an existing power capacity and thus opens new energy efficiency and management opportunities. In the context of IoT it’s also worth noting that LiFi’s data transmission speed (end 2015 speeds were achieved up to 1 Gbps and up to 224 Gbps in a laboratory environment) is beyond what is needed to connect IoT devices such as thermostats and presence detectors. However, the density of potential connections under a LiFi light spot is such that many devices can connect to a single LiFi access point and aggregate their bandwidth requirements. Other LiFi use cases include location-based services (for instance in retail), in-flight communication and entertainment, vehicular communication and underwater communications.