Evolution of Multi-Tier Transmission Towards 5G Li-Fi Networks

A design framework is presented in this manuscript for a novel visible light communications (VLC)-based multi-tier waveform. Conventionally, VLC waveforms are designed to target specific services. In services that require high-speed access, multi-carrier modulation techniques, i.e., orthogonal frequency division multiplexing (OFDM), is considered. For lower-speed access services, single carrier modulation techniques are considered such as phase-shift keying (PSK) or pulse-position modulation (PPM). The proposed design offers a universal-and receiver-independent multi-tier waveform that is expected to serve the requirements of fifth-generation (SG) wireless networks and beyond, including high-speed connectivity, sensing and positioning services. This allows a wide variety of devices to extract a useful portion of the received waveform associated to the targeted service while ensuring inter-service-interference-free operation. In addition, the proposed design aims for cooperative transmission and dimming control to enhance the lighting environment for better user experience. The paper provides a detailed description of the design process and the experimental evaluation. The experimental results indicate that the designed waveform can offer dimming control over 60% of the light-emitting diode (LED) full dynamic range, while maintaining bit-error rate (BER) of $7\times 1{0}^{-5}$ for 64-quadrature amplitude modulation (64-QAM).