Research at the Li-Fi Centre, University of Edinburgh

Consumer market research published worldwide indicates that future networks will be faster but capacity problems could still remain [1]. It further reveals that ‘topology’ – the make-up of transmitters providing the network signal – will be increasingly important for meeting demand in densely-populated areas. We can find a solution to this problem if we look at the results published on human behaviour trends [2].

On average people spend more than 90% of their time indoors. An epidemiology survey conducted in USA and Canada shows that people on average spend about 10% of their time outdoors in summer-time and only 2-4% in winter-time. When indoors, people often if not always spend their time in the vicinity of light sources. Here at the Li-Fi Research and Development Centre, we have developed the technology to transfer lighting sources into energy efficient data transmission points so that the number of transmission points can be increased enormously. The lighting sources could provide both illumination and communication. It appears that evolutionally it is the most viable way to increase the number of transmitters in the network. One such technology which turns this vision into a reality is Li-Fi (Light-Fidelity) [3].

Li-Fi is a bi-directional, high speed, mobile networking solution using LED light bulbs. Future light bulbs will detect if there are users in its vicinity, and will seamlessly take over the communication from cellular Wi-Fi to Li-Fi. If users move away from its vicinity vice versa will happen. When there are no users within its coverage the communication functionality of the light bulb can be switched off.

On the flipside however, due to the propagation characteristics of the light and the physical characteristics of the lighting sources often lighting over the space is not uniform, and susceptible to temporary blockages and shadowing. Contrary to popular beliefs, recent research shows that reliable communication can still exist. Currently, we are researching ways to design hybrid Wi-Fi and Li-Fi systems to overcome such temporary outages.

Dushyantha Basnayaka

Li-Fi Research Associate

  1. OFCOM, “4G Capacity Gains”, Jan. 2011.
  2. P. Hoppe, “Different aspects of assessing indoor and outdoor thermal comfort,” Elsevier, pp. 661-665, 2002.
  3. H. Haas, “High-speed wireless networking using visible light” SPIE Newsroom 2013.