Link budget analysis for free space optical (FSO) communication under haze condition with adverse wavelength

Abstract

This paper presents the link budget analysis for free space optical (FSO) communication and the studies on how to reduce the attenuation effect to improve FSO link. The effects are primarily focused on the atmospheric attenuation on the received power. Transmission power is the main priority in link budget. The power used to transmit data is gradually decreased along the path due to attenuation effects such as weather conditions. Theoretically, more transmission power is received at the receiver when scattering is low due to low level of attenuation. Despite this limitation, FSO performance could be enhanced more by using various wavelengths of laser beam. The conventional generally used wavelengths are 785 nm, 850 nm, and 1550 nm. The result analysis shows that wavelength 1550 nm is better than the wavelength 785 nm and 850 nm due to the attenuation effect and link range. Wavelength 1550 nm has improved 83%, 89%, 24% and 26% on the system compared to the wavelength 850 nm and 785 nm based on the attenuation and distance at power received −50 dB, respectively. There is a huge difference in the attenuation effect and obviously wavelength 1550 nm capable to reduce the power loss more than wavelength 785 nm and 850 nm as it is not affected much by the heavy attenuation.