BER Analysis for BPSK Based SIM–FSO Communication System Over Strong Atmospheric Turbulence with Spatial Diversity and Pointing Errors

Free space optical communication (FSO) has much attention in recent years for the applications viz. inter-satellite, deep space communications, inter and intra chip communications. The performance of FSO systems sternly suffers from atmospheric turbulence due to the random nature of weather conditions. Spatial diversity is an emerging technique for improving the performance of the system over strong atmospheric turbulences. In this paper, the error rate performance of binary phase shift keying based subcarrier intensity modulated free space optical (SIM–FSO) communication system over gamma–gamma channel with pointing errors is investigated. Novel closed-form analytical expressions are derived for the average bit error rate of single-input multiple-output FSO (SIMO–FSO) system with various combining schemes. The error rate performance of SISO and SIMO–FSO systems are compared in terms of 2D and 3D plots.