Research at the Li-Fi Centre, University of Edinburgh

Due to the wide use of multi-media mobile devices, Wireless Fidelity (Wi-Fi) is getting more and more popular in public. Since 2013, more than 5 billion smart devices use Wi-Fi every day, and this causes a systems overload. This often happens often to people at airports and in crowded cafes. When a large number of people are within the same Wi-Fi access point (AP), the transmission resource allocated to each individual is very small and the user service would be seriously affected.

How can we solve this problem?

Light Fidelity (Li-Fi), which employs the visible light spectrum to convey digital signals, is seen as a potential technique in next generation wireless communication. In general, LED lamps are the best options for Li-Fi AP, and the signals are transmitted by modulating the illumination power. Due to the innate property of light, a Li-Fi transmitter can only serve a confined area, which makes it possible for a dense deployment of Li-Fi APs and massive reuse of the bandwidth. As a result, people previously in the Wi-Fi system can now be divided into several groups when using Li-Fi, and each user would achieve a higher data rate by using more of the transmission resource.

However, the light beams used by Li-Fi are susceptible to blockages, and the devices would be disconnected to the Internet when they cannot receive any light from the Li-Fi AP. What can we do? Recently research has been undergoing on Li-Fi/Wi-Fi hybrid network. The twins, Li-Fi and Wi-Fi, can be combined to offer a more efficient and robust wireless service. Li-Fi provides a high data rate and Wi-Fi guarantees an ubiquitous coverage. Thus, users can choose Li-Fi generally for high data rates, and automatically switch to Wi-Fi while the light is blocked or they move outside the Li-Fi coverage area. Since some of the network load is served by Li-Fi, people served by Wi-Fi can achieve better user experience by using more transmission resource. Li-Fi, which acts as a complement to Wi-Fi, can significantly improve the quality of the network. In the future, it can be imagined that the Li-Fi/Wi-Fi hybrid network can cover the whole world and really gives us a life without hidden corners of Internet.

Xiping Wu

Research Associate

Li-Fi Research and Development Centre