POF feeding in Li-Fi systems with MIMO approach

Most in-home, office and even industrial applications require simple maintenance, low-cost installation and upgradability in the future. These scenarios have a heterogeneous network, composed by a mix of wireline and wireless technologies, twisted-pair copper lines for telephones, Wi-Fi, multi-media on coaxial cable (MoCA) etc. Several network infrastructure approaches, based on silica fibers, copper wires and plastic optical fibers (POF) have been proposed and investigated. In the last years the wireless connectivity has become very popular, substituting the wired networks. However, the large amount of wireless devices connected is causing a congestion in the spectrum. Also, the coexistence of different networks increases the cost of installation, maintenance and complicates the upgrade new types of service [1][2].
Optical fiber becomes an ideal option because of its huge bandwidth, low losses, small dimension and insensitivity to electromagnetic radiation. Some types of fiber may be considered: silica single-mode fiber (SMF), silica multi-mode fiber (MMF) and POF. Large core POF is a very promising solution because of the smaller bending radius, low cost, plug and play feature, electromagnetic immunity and easy maintenance. SMF and MMF, require skilled professionals for installation, which increase the costs. Another approach that receives growing attention is visible light communication (VLC) transmission, using light emitting diodes (LEDs), which can be directly modulated and used as wireless transmitters [3]. The main idea is to implement a novel VLC system, which includes a POF backbone, with which it is able to offer a high data bandwidth using advanced signal processing and optical techniques (e.g. multiple input multiple output - MIMO), in order to increase the capacity of the system, in an IoT environment. To implement the multiple MIMO channels efficiently in a single POF, multiple wavelength channels will be used with a compact power combiner made using a single lens, and a wavelength demultiplexer made with thin film filters to separate them.