Performance Analysis of Free Space Optical Systems in the Presence of Channel Physical Limitations

Abstract

Abstract The atmospheric attenuation in optical waves due to low atmospheric visibility conditions causes a performance degradation of free space optical (FSO) communication systems. A simulation was conducted to determine the relationship between visibility in fog and optical attenuation (dB/km) at an optical wavelength of 1550 nm. In this paper, we investigate the bit error rate (BER) performance for free space optical systems operating over atmospheric attenuation channels. Simulation results are demonstrated to confirm the analytical results. From the results, we conclude that BER increases as the adverse weather and greater distance. The BER performance of free space optical (FSO) communication systems employing on-off keying (OOK) modulation format is derived. Because the fog consists mainly of particles much larger than the laser wavelength, the application of the Kruse equation to attenuation in fog is not appropriate. Because fog is the only type of weather that is likely to disrupt short (< 1 km) free space optical links, short FSO links will be necessary to meet the high availability requirements of the telecommunications industry. The key finding is that the generally accepted Kruse equation relating visibility and optical attenuation may be too pessimistic at low visibilities. A new equation describing the atmospheric attenuation of optical power is proposed.