Average bit error rate performance of direct current biased orthogonal frequency division multiplexing in free-space optical communications over weak turbulence

This paper addresses the impacts of biasing and clipping on free-space optical (FSO) communications system over weak turbulence channel employing direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM). With atmospheric attenuation, turbulence and pointing errors, we present a statistical model for the optical intensity fluctuation at the receiver. The average bit error rate (BER) performance is analyzed in the channel environment and a theoretical expression is obtained. The simulation results indicate that the impacts of biasing and clipping for the average BER performance of the DCO-OFDM FSO communications system can be alleviated by enlarging the value of the bias to a certain degree, and the derived theoretical expression matches with the simulation results.