A hybrid fiber/wireless link based on a single visible LED and free of opto-electronic intermediate conversion stages has been demonstrated for indoor communications. This paper shows the main guidelines for proper coupling in fiber/air/detector interfaces. Experimental demonstration has validated the design results with very good agreement between geometrical optics simulation and received optical power measurements. Different signal bandwidths and modulation formats, i.e., QPSK, 16-QAM, and 64-QAM, have been transmitted over 1.5 m polymer optical fiber (POF) and 1.5 m free-space optics (FSO). Throughputs up to 294 Mb/s using a 64-QAM signal have been demonstrated using a commercial LED, which paves the way for massive deployment in industrial applications.

This paper proposes and presents the first experimental demonstration of a high‐precision indoor 2D and 3D visible light positioning (VLP) system using an imaging multiple‐input multiple‐output (MIMO) configuration with supervised artificial neural network. The proposed system utilises four distributed transmitters and receiver with four photodiodes and an imaging optics. The experiments are conducted in a typical indoor environment with transmitter separations of 300 mm and a link distance of 1400 mm. The experimental results show 2D and 3D positioning accuracies of 3.7 and 51 mm, respectively. A simulation model is also developed for the VLP system to validate the experimental results. Further optimisation of the VLP system in the simulation platform leads to improved 2D and 3D positioning accuracies of 2 and 14.7 mm, respectively. The proposed system can be seamlessly integrated with existing lighting infrastructures and is also compatible with the MIMO visible light communication system, indicating the potential for practical implementation in integrated communications and positioning applications.

This work experimentally demonstrates, for the first time, a unified Radio-over-Fiber (RoF) fronthaul for simultaneous visible light communication (VLC) and millimeter-wave (mmWave) transmission, enabled by a directly modulated laser (DML) in a centralized free-running configuration. Photonic heterodyning of dual optical carriers is used to generate high-frequency signals with cost-effective and scalable operation, suitable for 6G fronthaul networks. Two hybrid scenarios are validated: (i) a Light-Emitting Diode (LED)-based VLC/mmWave link for low-bandwidth Internet of Things (IoT) -oriented services and (ii) a LASER-based VLC/mmWave link for high-speed indoor communications. Optimized power levels achieve error vector magnitude (EVM) values of 2.1% for VLC and 3.7% for mmWave, supporting data rates up to 1.65 Gbps and 692 Mbps, respectively. The inherent tunability of the free-running approach allows straightforward extension to sub-THz frequencies, positioning this architecture as a cost-efficient and future-proof solution for optical-wireless convergence toward 6G networks.

This work experimentally demonstrates the convergence of visible light communications (VLC) and millimeter wave (mmW) wireless access technologies by using a unified optical fronthaul link that provides simultaneous signals to be transmitted over light emitting diode (LED) and seamless antennas-based links, respectively. Frequency multiplication is provided in the fiber link by using a carrier suppressed Mach-Zehnder modulator (CS-MZM) that offers a high-quality signal generation at both baseband (BB) and mmW frequencies. Moreover, this flexible and efficient photonic signal generation approach uses a directly modulated laser (DML) to take advantage of the relative gain given by the combination of the DML chirp and the fiber dispersion in the mmW band. Experimental trials of simultaneous VLC and mmW access have been done over distances up to 2.5 and 4 m, respectively; with maximum throughputs of around 70.3 and 393.1 Mbps for signal bandwidths of 30 and 100 MHz, respectively. Moreover, the effective transmission of different M-QAM OFDM modulation formats validates the approach as a promising enabler for future convergent heterogeneous 6G networks.