Performance analysis of a hybrid FSO/mmWave/THz system for short-range communication under rain and fog conditions

Abstract

For fronthaul cellular networks, the suitability of a hybrid free space optical (FSO)/radio frequency (RF) high data rate communication systems such as millimeter wave (mmWave) and terahertz (THz) with reliable connectivity under weather conditions (rain and fog) is proposed and analyzed. The aim of this hybrid system is to suit short-range communication covering 5G/6G and beyond cellular networks. The 4 pulse amplitude modulation (PAM) scheme parallel transmission and adaptive receiver approach is considered for the work. The theoretical work on estimating the attenuation characteristics under various weather conditions is carried out followed by the simulation of a hybrid communication system for obtaining the received power at different link lengths. Based on the received power for a data rate of 1 Gbps signal-to-noise ratio (SNR) and bit error rate (BER) is calculated for a link length of 0.2 km, 0.5 km, and 1 km for 4 PAM. For varying fog conditions, mmWave/THz carrier is found to be suitable with a BER of 10−10 at a link length of 0.5 km. For varying rain rates, FSO performs well with a BER of 10−8. The link length and performance can be improved with increased transmit power in both communication systems. The THz carrier offers a high data rate, and a hybrid system is proposed with FSO/THz to have reliable connectivity in harsh weather scenarios.