Performance evaluation of direct-detection coherent receiver array for free-space communications with full-link simulation

Performance of the direct-detection coherent receiver array for free-space optical (FSO) communications is evaluated with a full-link simulation model. This FSO full-link model (from the transmitter to the receiver) is established based on the phase screen method and the coupling theory by considering the amplitude fading and the phase distortion caused by atmospheric turbulence. Via full-link simulation, bit error rates are evaluated using maximum ratio combining and equal gain combining algorithms based on single-photodetector direct-detection coherent receiver array with different receiver numbers. The improvement of spatial diversity is numerically demonstrated by comparing with the single receiver.