Long-Reach Passive Optical Networks and Access/Metro Integration

Abstract

The physical layout of cables and nodes in many of today’s passive optical networks (passive opticalnetwork (PON)s) still dates back to the early days of copper loop installations, with customer to exchange node distances limited to a few kilometers largely by the transmission distance of analogue telephony over the copper pairs. However, modern optical communication technologies can enable much longer transmission distances, and through the use of optical amplification can effectively integrate the access and metro portions of the network into a single all-optical communication system, which is commonly referred to as “Long-reach PON” (long-reachpassive optical network (LR-PON)) or “Amplified PON”. LR-PONs offer several advantages in terms of infrastructure sharing, network node consolidation and core network delayering. This chapter describes the history of the development of LR-PONs, the technical design and the enhancements that can be added, such as flexible or dynamic wavelength assignment and the benefits for the end to end network architecture when the LR-PON is used to its full capability. We use results from recent research projects to illustrate the advantages of changing the overall network architecture to enable much higher sustained user bandwidths while reducing power consumption per user and improving economic viability. We also review recent experimental demonstrations of the end-to-end operation of such systems which validate the viability of these concepts using currently available components and technologies.