Real-time PAM4 fiber-IVLLC and fiber-wireless hybrid system with a parallel/orthogonally polarized dual-wavelength scheme

A real-time four-level pulse amplitude modulation (PAM4) fiber-invisible laser light communication (IVLLC) and fiber-wireless hybrid system with parallel/orthogonally polarized dual-wavelength scheme is proposed and practically demonstrated. Real-time measurement of the PAM4 bit error rate (BER) is adopted to avoid the complex offline calculation by MATLAB. To our understanding, this study is the first to construct successfully a real-time PAM4 fiber-IVLLC and fiber-wireless hybrid system with parallel/orthogonally polarized dual-wavelength scheme. Through PAM4 signal modulation, parallel/orthogonally polarized dual-wavelength scheme, and fiber-IVLLC/fiber-wireless hybrid architecture, the total transmission capacities of systems are enhanced to eight times. With an in-depth investigation in this real-time PAM4 fiber-IVLLC and fiber-wireless hybrid system, BER, and eye diagrams are observed to perform impressively over the 25-km single-mode fiber transmission with 100-m free-space link/5-m RF wireless transmission. This real-time PAM4 fiber-IVLLC and fiber-wireless hybrid system reveals a notable one not only owing to its advancement in the incorporation of fiber-based backhaul and optical/RF wireless-based extender, but also owing to its advantage in the communication link for providing higher transmission capacities.