Comparative Analysis of the Unavailability Factors for Two Types of Optical Cable Section Repair under Conditions of Gradual and Sudden Failures

Abstract

The article presents a comparison of unavailability factors for two optical cable section types of repair under conditions of degradation and sudden failures. The first one involves replacing a section of optical cable in case of both degradation and sudden failure caused by outside interference. In the second type, the replacement of the optical cable section is carried out only in case of degradation failure. In case of a sudden failure, the optical cable is repaired by connecting at the point of breakage. To show the degradation process and analyze the impact of sudden failures, mathematical models of the semi-Markov process are used, which allow to determine the average recovery time and time to failure, the unavailability factor, as well as to estimate the duration of the degradation cycle. The degradation cycle covers the duration of optical cable operation from the initial state to the degradation failure, including the recovery time after sudden failures. This parameter can be an estimate the service life of optical cable or its section. At the same time, it is assumed that during operation, due to the cable sections replacement, the whole optical cable will be replaced. It is shown that the degradation cycle of the section in the first type grows with increasing the sudden failures rate, and in the second type, on the contrary, decreases compared to the planned value determined in the absence of sudden failures. The more frequent sudden failures occur, the more noticeable the difference in the values of the optical cable section unavailability factor calculated for both types of repairs. These results can be used to estimate the time needed to replace sections of optical cable due to degradation, as well as to select the optimal strategy for maintenance and repair of the access network optical cable.