WDM based FSO link Optimization for Different Weather Conditions

Abstract

Free Space Optics (FSO) or Optical Wireless (OW) is a high speed and secured wireless communication technology. This thesis presents the understanding and simulation of FSO communication link for different weather conditions and analyzes the performance of the FSO system by using parametric optimization. The modulated optical signal transmission through the atmosphere can work for several kilometers of link distance. Communication is possible if there is clear line of sight between the optical source and the photo-detector with enough transmitting power. Free space optical communication offers last mile solution where optical fiber cable is not practical.

The performance of a free space optical communication is dependent upon the atmospheric effects like scintillation, atmospheric attenuation, building sway, sun radiations and obstruction in line of sight. In this project OptiSystem is used as simulation tool to simulate the different weather effects for WDM based FSO link for the data-rate of 2.5 Gbps and wavelength of 1550 nm.

The effect of atmospheric weather conditions has been observed and accordingly parameter optimization has been simulated. The simulation results shows that since these effects attenuate the signal, the link range and other parameters can be optimized to get better performance. Optimization parameters may vary for different attenuation levels. The FSO link of the bit rate of 2.5 Gbps and wavelength of 1550 nm is also optimized for the weather condition in Ahmedabad. The BER achieved is for optimized link range. The optimized link range for light rain, medium rain and heavy rain is achieved as 15.6 km, 6.1 km and 3 km. It shows that a WDM based FSO system can be implemented using the design for minimum of 3 km range for Ahmedabad weather conditions.