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The Faulty Optical Fiber Mechanism and Fault Localization Techniques in TDM-PON Network

In this paper, the mechanism of failure (breakdown) detection in an optical fiber line will be studied. The objectives of this paper are to understand in detail the mechanism of faulty fiber and previous recommended fault localization techniques for fiber-to-the-home (FTTH) access network. The detail failure analysis results, failure mechanism, and eliminating solution will be studied and presented. It was reported that any failure in FTTH is affected the triple-play services transmission. Conventionally, a fiber fault in FTTH can be located using optical time domain reflectometer (OTDR) upwardly from customer premises toward central office (CO). Technician is sent to the optical network terminal (ONT) or optical network unit (ONU) side to inject an OTDR pulse into the faulty fiber. This approach would require much time and effort. Moreover, OTDR can only display a measurement result of a line in a time. Therefore, it becomes a hindrance to detect failure of optical line with a large number of customer premises and large coverage area in the fiber plant by using an OTDR. Besides, it is difficult to detect a failure in optical line equipped with passive optical splitter by using a conventional OTDR in the CO downwardly from CO towards the customer premises, because the Rayleigh back-scattered (RBS) light from different branches overlap with each other in the OTDR trace and cannot be distinguished. To overcome these problems to achieve desired network survivability, we introduced a MATLAB-based graphical user interface (GUI) named Centralized Failure Detection System (CFDS), which is potentially used to increase efficiency and flexibility of FTTH, particularly in monitoring the optical signal flow and locating a fiber break downwardly from CO. To perform all the mentioned tasks, interfacing between the developed program with OTDR is required.