Design and security analysis of an image encryption based on gigabit passive optical network employing fiber-FSO protection at the last mile

Abstract This work offers an extra free-space optical (FSO) and protected fiber connection channel with self-repair capabilities to protect against fiber failures in gigabit passive optical networks (GPON). The new optical network unit (ONU) and optical line terminal (OLT) in the suggested PON architecture provide self-protective capability against fiber breakpoints. An integrated single mode fiber (SMF)/FSO link not only keeps data transfer uninterrupted even when fiber link installation is limited by environmental boundaries, like a wide river or the space between two mountains. In clear Iraq’s atmospheric conditions, the network system gets an optimum range transmission of favorable weather (fog) in both directions simultaneously to wired and wireless users over a bidirectional feeder fiber link 75 km and 430 m FSO or distribution fiber (DF) for downstream (D/S) and fiber feeder link 75 km and 230 m FSO or DF for upstream (U/S) with improved fault protection capability for both directions, while the range of FSO is reduced to 400 m, 260 m, and 250 m for D/S and 220 m, 160 m, and 150 m for U/S for snow, rain, and dust respectively. Asymmetric 2.5/1.25 Gbps for D/S and U/S has been used to achieve an acceptable minimum receiver sensitivity of −33.4 dB m for uplink and −34.4 dB m for downlink with a splitting ratio of 1:16.