Enhancing resource utilization in radio-over-fiber using hybrid modulation scheme

This paper presents a hybrid modulation scheme for radio-over-fiber (RoF) systems, which integrates baseband-over-fiber and conventional radio-over-fiber transmission. The proposed approach enables the simultaneous transmission of a baseband and an RF signal over the same wavelength using a single fiber and a single photodetector, without relying on conventional multiplexing techniques. This is achieved by initially modulating the optical carrier with a baseband signal and subsequently modulating this already modulated optical carrier with a radio frequency (RF) signal. This enables the use of existing optical infrastructure to transmit additional RF signals. The paper presents a mathematical framework supported by experimental and simulation results. The scheme has been tested for different fiber lengths, RF and optical power levels, and data rates, demonstrating an acceptable bit error rate (BER) of $10^{-9}$ with the necessary parameters outlined.