BER performance of DPSK subcarrier modulated free space optics in fully developed speckle

Abstract

In this paper a DPSK subcarrier intensity modulated (SIM) free space optical (FSO) link is considered in negative exponential atmospheric turbulence environment. To mitigate the scintillation effect the selection combining spatial diversity scheme (SelC) is employed at the receiver. Bit error rate (BER) analysis is presented with and without SelC spatial diversity, and it is shown that at BER of 10-6 using four independent PIN-photodetectors, a diversity gain of not less than 38 dB is achievable.