BPSK based SIM-FSO communication system with SIMO over log-normal atmospheric turbulence with pointing errors

In this paper, we analyze a bit error rate (BER) as well as outage probability in a free-space optical (FSO) link. Log-normal atmospheric turbulence with an effect of pointing errors (PE) is used to model the FSO channel. Binary phase shift keying based on subcarrier intensity modulation is employed. The BER degradation due to the effect of PE is improved by applying single-input multiple-output (SIMO) technique using maximal ratio combining. The outage probability and BER closed-form expressions are derived for all cases which are confirmed by integral expressions. The numerical results show that the BER can be improved by using SIMO technique. For instance, the BER is 1.884×10−6 at 0 dBm transmitted power in the case of without using SIMO, while the BER become 3.223×10−21 at 0 dBm in the caseof applying the SIMO technique.