Presentation at the PHOTOPTICS 2022, OWC workshop

Christoph Kottke, Dominic Schulz and Volker Jungnickel, “LiFi Use Cases Tested in Real Environments”, PHOTOPTICS 2022, OWC workshop

Abstract: The amount of wireless data traffic and the number of devices continues to grow at an exponential rate. Over the past decades, we have seen waves of innovation to enhance the bit rates (bit/s) and the density (bit/s/m2) that can be provided by wireless radio networks, but the wireless technology needed to support this also becomes increasingly complex. One can argue that a disruptive change to include optical wireless communications, which is also denoted as LiFi, becomes attractive. Light sources such as light emitting diodes (LEDs) can offer gigabits per second with simple emitters and receivers at very low cost. In this invited talk we present selected use cases for LiFi in the future IoT, which have been tested in real environments, i.e. fixed wireless access (FWA), for indoor positioning and industrial LiFi integrated with 5G. Our goal is to develop a flexible system concept for LiFi to serve a wide diversity of use cases, and show in this way that LiFi is increasingly mature and promising to serve a mass market. The requirements, key features, demonstrator realizations and early results for each selected use case are presented and discussed. The work is conducted in the EU project ELIOT [1]. Fiber-to-the-home (FTTH) deployments allow Gbit/s data rates and robustness but suffer from high installations cost, especially due to digging the fiber. An alternative is the fixed wireless access (FWA), where the last hop to the customer is realized with a wireless link. Instead of connecting each household with a fiber, the fiber will only be deployed at the curb, e.g. the street lights in a residential area, and the final hop to the building is less costly using so called wireless-to-the-home (WTTH) nodes. We showcase an optical wireless link with Gbit/s data rates for fixed wireless access. The installation took place in a courtyard under outdoor conditions and over typical link distances. The performance of the LiFi link is investigated and compared against a 60 GHz radio link, addressing various aspects like the transmission through metal-coated insulation glass. Besides communication, smart manufacturing calls for positioning to facilitate various new Industry 4.0 applications. For example, reliable indoor positioning is necessary for using intelligent transport systems (ITS) that transport parts on pallets from one predefined locations to another. We present a LiFi-based positioning system, utilizing fields from physical layer packets defined in the G.9991 LiFi standard. The installation was done in a factory environment and allows accuracies of a few cm. Key challenges such as sufficient coverage and time synchronisation are discussed, as well as requirements for integration into future LiFi chipsets. The ongoing shop floor digitalization confronts manufacturers with challenges in computer networks. WiFi became a standard for enabling mobile applications in factories, but suffers from adjacent WiFi networks operating in parallel. Consequently, WiFi is a less reliable wireless technology for smart factories and could be complemented by LiFi and 5G. With a combination of the technologies, we aim at improved flexibility, reliability, wider coverage, and higher throughput for fixed and mobile devices in factories. We also demonstrate the use of LiFi as a non-3GPP access technology, connected to the 5G core network and describe our initial test results. [1]