End-to-end average BER analysis for multihop free-space optical communications with pointing errors

This paper addresses the end-to-end average BER (ABER) performance of decode-and-forward (DF) relay free-space optical (FSO) communications over weak and strong turbulence channels with pointing errors. For the weak and strong turbulence channels, the probability distribution function (PDF) of the irradiance can be modeled by a lognormal and Gamma–Gamma distribution, respectively. Considering the effects from atmospheric attenuation, turbulence and pointing errors, we present a statistical model for the optical intensity fluctuation at the receiver. Then the end-to-end ABER performances are analyzed and derived closed-form expressions are obtained. The simulation results indicate that the derived closed-form expressions provide sufficiently accurate approximations.