A Model of a Protected System Under Unreliable Check-Out Conditions

This paper presents the continuous time operation models of optical line terminal for passive optical access networks with a number of protection schemes. Latent failures are considered to be the main reason for optical line terminal operational faults. The proposed models take into account the events of technical check-out control of the major and redundant terminals, as well as their restoration to a normal operational state after the failure detection. Based on steady-state probabilities, calculations of stationary availability factor and total availability factor are performed, with consideration of check-out errors of first and second kind.