Comparing the rain effects on hybrid network using optical wireless and GHz links

Optical wireless link provides high bandwidth solution to the last mile access bottleneck. However, an appreciable high availability of the link is the basic requirement of any communication application. Free space optics (FSO) links are highly weather dependent that reduces the link availability. Hybrid networks consisting of Free Space Optics (FSO) link and back up link in the GHz frequency range renders high availability besides providing comparable data rate. The back up link should be nearly immune to weather attenuation for achieving carrier class availability. Among all the attenuation factors for GHz back up link, rain is the most significant. In this paper effects of rain on FSO and GHz frequency range links are studied and some measurement results are presented. This analysis can help in selection of frequencies with least rain attenuation as a back up link.