Achieving carrier class availability of FSO link via a complementary RF link

Due to the difficulty of deploying fiber-to-home, the solution for the last-mile problem remains an unsolved challenge. Among all the alternatives, free-space optics (FSO) shows great potential due to its non-interfering nature and abundant available bandwidth. However, because the operational status of an FSO link is highly weather dependent, feasibility of using FSO to deliver data to end-users remains questionable. A hybrid architecture that utilizes the complementary nature of FSO and radio frequency (RF) links with respect to their individual weather sensitivities has been proposed to significantly increase availability. According to this architecture, we developed a channel model integrating the RF and FSO channels. Experimental measurements are also taken into account in order to verify validity of the model. Based on the model and available weather condition data, we concluded that the hybrid link does demonstrate significantly better availability than the FSO alone case. Carrier class availability can be achieved.