Performance Analysis of MPSK FSO Communication Based on the Balanced Detector in a Fiber-Coupling System.

An average bit error ratio (ABER) performance model for multiple phase shift keying (MPSK) based on a balanced detector with a fiber is presented in the free-space link for the first time. The Johnson S-B probability distribution function (pdf), to the best of our knowledge, is first experimentally explored, which can be used to describe the fading characteristics of an optical signal coupled into a single-mode fiber (SMF) in an atmospheric turbulence channel. Subsequently, an ABER expression is established by combining the photon characteristics of the balanced detector with the fiber. The numerical results show that the system has the most superior ABER performance when the splitting ratio is 0.5 and the quantum efficiency of the two photodetectors is equal. Moreover, the communication performances can be optimized by adjusting parameters, such as increasing the system bandwidth, selecting the appropriate modulation order, and improving the received optical power. Finally, the MPSK-signal-to-noise-ratio (SNR) model is also studied to evaluate system communication performance. Through our asymptotic analysis, if the required ABER falls below the 7% forward error correction (FEC) limit of 3.8 x 10(-3), the SNR should maintain at least 38 dB or more, while the normalized fluctuation variance deteriorates to 5.2441. This paper provides a parameter reference for designing the MPSK free-space optical (FSO) communication system, especially the fiber-coupling receiver.