• Rachana Jadvani
• Rina Parikh

Free space optical (FSO) communications, is a cost-effective and high bandwidth access technique, which is receiving growing attention with recent commercialization application. This paper analyses the performance of FSO communication and investigates the techniques to improve the performance of free space optics. Spatial and wavelength diversity techniques are studied and the effect of diversity on the performance of FSO communication link in atmospheric turbulence conditions is analyzed. Wavelength diversity technique is used to reduce the fading under strong atmospheric turbulence condition. Mathematical expressions for the estimation of the outage probability under strong atmospheric turbulence conditions are derived and considerable improvement is found using wavelength diversity. Performance of FSO link with different wavelengths and different aperture area of optical detector has been analyzed. Effects of different wavelengths on visibility range and quality factor of optical receiver is simulated to find the performance of FSO link. It is concluded that due to reduction in scattering loss at higher wavelength; as wavelength increases, quality factor of receiver improves. Quality factor of optical receiver is also improving with increment in aperture area of detector due to increment in sensitivity of receiver due to large aperture area. The link availability calculations were made based on the power budget analysis of FSO link and on the statistical analysis of visibility data. Four different cities were selected across different geographical conditions across the country to compare the weather conditions and the performance of FSO link for different cities of India is calculated. It is concluded that, for a given link. the performance of FSO link is not similar for all the geographical area as the visibility conditions are different. It is shown that the availability and reliability of the FSO link can be improved by making survey of the geographical area where the link has to be established. These data are varying seasonally and with location of the particular area. Scattering and attenuation may be caused more in low visibility condition. Link design of the FSO link can be made after that and better link can be proposed so the desirable availability and BER performance can be achieved.

optical communication , wavelength , diversity , BER

"BER PERFORMANCE OF FREE-SPACE OPTICAL COMMUNICATION WITH WAVELENGTH DIVERSITY", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.5, Issue 7, page no.164-168, July-2018, Available :http://www.jetir.org/papers/JETIRC006337.pdf

"BER PERFORMANCE OF FREE-SPACE OPTICAL COMMUNICATION WITH WAVELENGTH DIVERSITY", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.5, Issue 7, page no. pp164-168, July-2018, Available at : http://www.jetir.org/papers/JETIRC006337.pdf