Service-affecting optoelectronic failures in FITL systems: downtime, repair actions, and maintenance expenses

This paper provides a quantitative examination of lifecycle cost versus operating environment for fiber-in-the-loop (FITL) systems. It focuses on reactive maintenance due to service-affecting failures of optoelectronic elements. The scope is limited to passive point-to-multipoint star local networks, engineered to deliver narrowband telecommunication POT´s services, with hybrid fiber/copper architectures (i.e., the customer´s terminal equipment (TE) is connected with symmetrical copper pairs to the optical network unit or ONU of the FITL system). The influence of service-affecting failure rates, times to repair, and the various temperature environments faced by the optoelectronic equipment is evaluated in terms of: (i) service downtime; and (ii) the number of repair actions and maintenance expenses due to service affecting failures on the optoelectronics-related elements. The author estimates some $60 expenses, per line during a 20 year lifecycle, if the ONU is in a partly controlled temperature environment, and some $170 in an uncontrolled temperature environment. A downtime, per line per year, lower that 60 minutes can be achieved in both types of environment. Placing the ONU in a partly controlled environment, however, enables a 100% increase in the times to repair or, alternatively, some 90% decrease in the downtime