Novel adaptive hard-switching based hybrid RF-FSO system architecture using two threshold values in the presence of atmospheric turbulence and pointing error

In recent years and in the ongoing development of all-optical systems, we propose two novel hard-switching based hybrid RF-FSO system architecture in the presence of atmospheric turbulence and pointing error. In the first proposed scheme, the hybrid Relay based RF-FSO link (path 1) is paralleled with a RF link (path 2). In the second scheme, the FSO (path 1) and relay based RF-FSO (path 2) links are paralleled. In these two novel schemes, we tried to increase the lifetime of the main path using the double threshold SNR technique. In these scenarios, the hard switch selects one path as a data transmitter using two threshold values. The RF and FSO links are modeled by Rayleigh and Gamma-Gamma distributions, respectively. We derive closed-form expressions for the Outage Probability (OP). Also, the Intensity Modulation with Direct Detection (IM/DD) and the heterodyne detection techniques are used. The performance of proposed systems are presented in the different atmospheric and pointing error conditions. Numerical results show that the proposed schemes have succeeded in achieving the set goal. •Double threshold SNR scheme using the relay based hard switch technique has been proposed.•The RF and FSO links are modeled by Rayleigh and Gamma-Gamma distributions, respectively.•The All closed-form equations for the outage probability are formulated using (IM/DD) and Heterodyne detection technique. The closed-form expressions for the Outage Probability (OP) have been derived.•The numerical results for both systems have been presented in presence of pointing error and atmospheric turbulence conditions. - Proposed systems increase the transmission lifetime of optical links.