UDWDM-PON using low-cost coherent transceivers with limited tunability and heuristic DWA

A new passive optical network (PON) for access, making use of ultra-dense wavelength division multiplexing (UDWDM) by densely spacing channels by a few gigahertz and introducing the "wavelength-to-the-user" concept, is proposed. The key challenge will be developing low-cost coherent transceivers that provide an excellent selectivity while avoiding filters and furnishing high sensitivity, which will allow high splitting ratios, large numbers of users, and long-distance reach. The optical distribution network (ODN) at the outside plant is based on splitters and is kept compatible with legacy systems. Optical network unit (ONU) designs realized with coherent transceivers using one or two lasers are presented, and the corresponding optical line terminal (OLT) architectures are introduced. The ONUs at the customer premises have lasers with limited thermal tenability, and their wavelengths are randomly distributed in a band. By using heuristic dynamic wavelength assignment (DWA) schemes and extending the original working band, the required optical band is obtained and optimized. In activation processes, ONU acceptances up to 99.9% are achieved. Furthermore, in operation scenarios under indoor and also under outdoor environmental conditions, ONU blocking probabilities below 0.1% and ONU availability ratios (OARs) up to 99.9% are demonstrated. The PON is dimensioned according to the number of deployed users and system reach; moreover, power safety and also fiber non-linearities constraints are evaluated, illustrating the characteristics of the projected network. Finally, the coexistence with legacy networks is discussed.