Statistical design of long optical fiber systems

A design strategy is proposed to minimize the most likely overall system cost, that is, the sum of the equipment installation cost and the repair cost over the lifetime of the system. By choosing a repeater spacing larger than that dictated by a worst-case design, the possibility of system failure due to negative system margin is admitted. However, for a correctly chosen repeater spacing, the most likely cost of repairing these failures, when added to the reduced installation cost, is significantly less than the system cost of a worst-case design. This statistical design strategy is applied to a 565-Mb/s single-mode optical fiber system operating at 1.3 mu m. Several different failure modes which can occur in such an optical fiber system are identified, and the probability density function for each type of failure is calculated. It is shown that the design strategy leads to significant savings compared with worst-case design. For typical device parameters, a saving of about 30% in equipment installation and repair costs over the lifetime of the system is reported.<>