Hybrid fiber-to-the-x and free space optics for high bandwidth access networks

The authors demonstrate an implementation of hybrid fiber-to-the-x (FTTx) and free space optical (FSO) technologies as another alternative solution to bring light-speed performance to the residential users. A simulation experiment was performed with a 20 km single-mode fiber spanning from the Central Office to 1:32 splitter, before the signal propagated through the air to FSO receivers which were individually equipped with an Optical Network Unit (ONU). A downstream performance of the video signal transmitted at 1550 nm wavelength with a bit rate of 1 Gbps was studied under different weather conditions. The results show that for an acceptable bit error rate of 10⁻⁹, 32 ONUs are supportable at a combined FSO: FTTx distance ratio of 20:4.8, 20:2, and 20:1.4 km during clear weather, average and heavy rain, respectively.