Hitless Switching Scheme for Protected PON System

The passive optical network (PON) shares feeder transmission facilities to provide broadband services economically. To enhance PON survivability, ITU-T Rec. G.983.5 defines some protection switching methods. These methods, however, always bring about signal loss when switching is performed. Another related problem occurs when the network operator replaces one optical fiber cable with another that takes a different route due to construction activities like social infrastructure renewal. If hitless switching is available, the operator can carry out that activity anytime without impacting users, and can also offer higher-grade broadband services. Thus a hitless protection technology for PON systems is very attractive and useful. This paper proposes hitless switching schemes for protected PON systems based on the PON´s ranging functionalities. We also present a specific design example for GE-PON.