Investigated was the bit error rate (BER) performance of transmitting BPSK signal of the radio over free space optical (ROFSO) system in a Gamma Gamma atmospheric turbulence model. The average BER expression of this system was derived and the results were obtained by both theoretical arithmetic and numerical simulations with Matlab software. It is shown that, compared with common FSO system using OOK modulation, ROFSO system can own better BER performance, and it requires no threshold decision. Meanwhile, the effects of the propagation distance, the diameters of the receiving lenses and the structure constant of the refractive index on the system’s performance are discussed.
