TDMA Scheduling in Spatially Extended LiFi Networks

Abstract

Optical Wireless Communication (OWC) has attracted significant attention from academia and industry as a promising solution to complement traditional radio frequency communication. In Light-Fidelity (LiFi) networks, to enable soft handover and provide robustness against blockage of the line-of-sight links, LiFi receivers are designed to see multiple LiFi transmitters within their field-of-view. To trade-off spatial multiplexing with harmful interference, a proper user scheduling technique is required. In this work, we first derive practical and exact expressions for determining which simultaneous transmissions will create harmful interference and should be scheduled in multiple time-slots. Afterwards, relying on this expression, we propose our semi-distributed Spatially Extended TDMA algorithm, which is based on a time division contention–free access scheme. In contrast to more complex algorithms in the state-of-the-art, our scheduling protocol can reduce the computation time while also achieving a superior minimal user throughput. For a scenario with 9 transmitters and up to 15 receivers, our protocol is at least a factor 120 faster and can improve the minimal user throughput up to 91%, making it suitable for practical roll-out as a promising solution for very dense LiFi networks.