By Harj Ghuman & David Job, Cox Communications
While Coherent optics are ubiquitous in the MSO metro core and backbone optical networks, initial planning and use cases are now being investigated for Coherent technology in the Access domain. Cable HFC optical networks are rapidly evolving from traditional analog to digital DWDM infrastructures that enable the adoption of Distributed Access Architectures (DAA) such as Remote-PHY and Remote MAC, which provide higher performance, lower overall optical costs and simplified network designs.
The available digital DWDM infrastructure within the Access network will accommodate the pervasive 10G NRZ DWDM connections associated with DAAs as well as the introduction of Coherent technology to address high bandwidth applications (i.e. MDU service delivery and Enterprise Business services.) In that regard we detail proof of concept testing over 40 and 60 km distances with bi-directional Coherent 100G/200G and 10G NRZ DWDM wavelengths placed adjacent to each other on the same fiber, using our Cox designed Optical Communications Module Link extender (OCML) and a Mux/DeMux. Use cases of a converged Access network consisting of 100G/200G Coherent, 10G DWDM and PON are presented, allowing operators to deploy a solution which is technology agnostic and able to support a multitude of services over the same network, while fully utilizing existing fiber assets.