Indoor wireless networks have been playing an important role in our everyday lives. Due to the Covid-19 pandemic, people have to stay at home to avoid physical contact. The need for communication through the Internet, for both work and entertainment purposes, has been increasing since the year 2020.

Nowadays, the number of mobile applications dramatically grows. Many mobile applications need a reliable Internet connection, some of them require a large amount of bandwidth for wireless communication. Radio frequency (RF) spectrum used for current wireless local area networks (WLANs) is a limited resource. Due to the booming demand for indoor wireless traffic, the RF spectrum becomes more and more crowded.

Many researchers proposed to use resources with higher frequencies in the electromagnetic spectrum. Recently, visible light communication (VLC) has attracted considerable scientific interests. VLC uses off-the-shelf light-emittingdiodes (LEDs) and photodiodes (PDs) to transmit data via visible light. Indoor wireless networks using VLC for data communication, typically called optical attocell networks, have been proposed to complement the RF-based WLANs.

“In optical wireless networks, LED lamps are base stations (BSs) which communicate with user equipment (UEs) using VLC. These communication links form an access network. The access network is connected to the Internet through a backhaul network which consists of communication links between BSs and a gateway. Wired backhaul networks send data through cables. High cost and complexity for installation and maintenance are inevitable. Using VLC for backhaul data transmission is straightforward, as the VLC-based backhaul network is cost-efficient and does not require extra cables or control units”, Yuhui explains.

“However, there are many open issues for VLC-based backhaul networks. First, although the line-of-sight (LOS) VLC link can achieve high data rates, the LOS condition may not be fulfilled in many indoor applications. Non-LOS VLC links suffer from multipath effects and cannot provide reliable backhaul data transmission. Moreover, VLC links are blocked by human bodies or furniture as the visible light cannot pass through opaque objects. This shadowing effect degrades the performance of not only VLC backhaul links, but also access links. Finally, the performance of VLC-based backhaul links depends on the alignment of auxiliary LEDs and PDs which are used for backhaul communication”, Yuhui continues.

“To address these issues, I have presented in my dissertation a novel VLC-based backhaul network using the mirroraided non-LOS configuration. This backhaul link configuration can be used in many indoor applications when the LOS condition cannot be ensured. The purpose of my dissertation is to design a robust mirroraided non-LOS VLC link-based backhaul network”, Yuhui  concludes.

Read a more detailed summary or the entire PhD

-

PhD Title: A Robust Wireless Backhaul Solution for Optical Attocell Networks

-

Contact: Yuhui Wu, Didier Colle, Mario Pickavet

-

Editor: Jeroen Ongenae - Illustrator: Roger Van Hecke