Performance Analysis of HAPS integrated Hybrid RF/FSO System Cascaded With an UWOC Link

Abstract-In this paper, the performance analysis of a decode and forward relay (DF) based High Altitude Platform System (HAPS) assisted hybrid radio frequency (RF)/ free space optical (FSO) system to provide connectivity to the underwater destination through an underwater optical communication (UWOC) link has been investigated. The source communicates with the underwater destination with the help of a HAPS system. The source is connected to HAPS through a hybrid RF/FSO link. The HAPS acts as a DF relay which decodes the signal it received, then re-encode it and then forward it to the water surface relay through another hybrid RF/FSO link. Here both in the HAPS and water surface relay, the selection combining (SC) technique is used. The signal received at the water surface relay is further forwarded to underwater destination though an UWOC link. The outage probability of the proposed system has been derived and their statistical characteristics have been developed. The observed results shows that the outage probability of the system gets affected by RF shadowing, FSO turbulence, variations in temperature and Underwater Optical Turbulence (UOT). Moreover, the outage probability of the system is also dependent on the different HAPS parameter of the FSO link like beam width, angle of deviation etc. The asymptotic results are also shown for different analytical results and it resembles with each other.