By Edward W. Boyd, Ciena Corporation; John Bender, GCI Communication Corp; Kevin Noll, CableLabs; James Harley, Ciena Corporation
The broadband access industry has seen remarkable growth in its short 30-year life beginning in the late 1990’s with technologies delivering 1.5Mbps. Today’s broadband networks, delivering access at speeds over 10 Gigabits per second (Gbps), enrich the lives of billions of people around the world by enabling individuals to interactively share their experience and by removing the geographic and economic barriers to educational resources, health care, jobs, and so much more.
Anticipating a continuing need to increase capacity and speeds in the access network, the industry has begun work to create a 100 Gbps Passive Optical Network (PON). Some proposals for 100 Gbps PON focus on using tried-and-true Intensity Modulation-Direct Detection (IM-DD) technology that has enabled PON since the 1990s. Coherent optical transmission has matured significantly over the last decade creating an ecosystem that is primed to apply this technology in the cost-sensitive access network.
Multiple standards organizations are hearing proposals for a 100 Gbps Coherent PON, but no specification is complete.
Solutions must have a low Optical Network Unit (ONU) cost, must operate on existing/legacy Optical Distribution Network (ODN), and must reuse existing PON standards where possible. It is also crucial to maximize compatibility with back-office systems, ensure smooth integration into network operations, and to enable reuse of existing system software and PON standards.
This paper will analyze the viability of a specific coherent PON physical layer (PHY) based on coherent transmission that operates seamlessly with the PON channel management protocols defined in ITU-T G.9804.2 and ONU management defined in G.988. The authors have direct PON experience as an operator, standards organization members, and technology vendors. The analysis will include relative cost, optical budget, system throughput, latency, jitter, and the applicability of coherent PON as a replacement for point-to-point fiber solutions used in backhaul, enterprise connectivity, and aggregation.