Promising evolution paths for passive optical access networks

Two evolution paths for power-splitting passive optical access networks are presented and discussed, where the focus is on both introduction of protection against fibre cuts and increase of bandwidth per customer. We show that fibre ring topology enables an easy introduction of protection to such tree-based systems. Wavelength division multiplexing (WDM) is assumed to be the key technology for bringing about more bandwidth to the customer in a later stage of network evolution, and first using coarse channel spacing. If an adequate demand for bandwidth as well as for protection is predictable it is useful to switch over to WDM fibre rings with optical add-drop multiplexing.