Research at the Li-Fi Centre, University of Edinburgh
Since Li-Fi technology was first introduced to the public by Professor Harald Haas in his 2011 TED Global Talk, it has attracted ever increasing attention from many researchers.
Li-Fi is a high-speed, bidirectional and fully networked broadband wireless technology which is aimed at offloading the existing Wi-Fi technology. A Li-Fi access point (AP) can serve multiple users simultaneously within the area of its coverage, and this is termed an ‘optical attocell’ .
In an optical attocell the wireless connection from the AP to an end-user relies mainly on a line of-sight (LOS) link . Any obstruction between the serving AP and the user would cause a blockage with the user losing the wireless connection. How are we going to tackle this challenge?
Imagine you are watching a TV program in a room and then somebody blocks your sight-line. However, if there is a mirror in the room that can reflect the TV image into your field of vision, you would still be able to watch that program via the mirror. This everyday example highlights a similar approach to resolve the LOS blockage for Li-Fi networking. It consists of bypassing the blocked link through a neighbouring attocell. As a result the reliability of the Li-Fi service is improved by means of attocell cooperation. Hence, the attocell cooperation scheme can be viewed as an effective solution to reinforce the signal quality for a user whose LOS is obstructed. But, is that the only advantage of this scheme?
In the optical attocell system, available spectrum resources for communication are reused among a number of Li-Fi APs and shared with all of the users that have access to the network. Another benefit of the attocell cooperation scheme is that it can help improve the utilization of spectrum resources in addition to the operating overhead. Furthermore, the use of the attocell cooperation provides a means for employing different inter-cell interference (ICI) coordination techniques to further improve performance of a multi-user Li-Fi network. My research work that considers these cases is in progress, and here is the right place to come back and check for the latest results of my research! H. Haas, “High-speed wireless networking using visible light”, SPIE Newsroom, Apr.19 2013.  H. Elgala, R. Mesleh, and H. Haas, “Indoor Optical Wireless Communication: Potential and State-of-the-Art”, IEEE Communications Magazine, vol. 49, no. 9, pp. 56–62, Sep. 2011.
Li-Fi PhD Research Student