By Mike Cooper, David Job & Bill Wall, Cox Communications
The hybrid fiber coaxial (HFC) network has served as both a reliable and flexible architecture which has enabled cable operators to continue to migrate their networks to meet the exponential growth in bandwidth demanded by both commercial and residential customers. This architecture has supported cost effective capacity increases with minimal disruptions to the network and end-users. While more recent efforts have focused on building fiber-to-the-home (FTTH) networks, they are generally quite expensive with cost estimates often nearing $1000 per household passed (HHP) or greater. Given the long-term capacity of an all-fiber network, it may be considered the obvious choice for green field deployments.
However, for brown field areas, the cost of a FTTH network upgrade drives the continued evolution of the existing HFC architecture as a better choice.
The introduction of extended spectrum Frequency Division Duplex (FDD) Data Over Cable Service Interface Specification (DOCSIS) within the DOCSIS 4.0 specifications enable that continued evolution by defining standards that for Cox would support capacities as high as 12 Gbps on the downstream and 3Gbps on the upstream across the legacy HFC node and amplifier (N+X) architecture.[CM-SP-PHYv4.0]The strategy for operational implementation of this upgrade will be a critical component to the success of multi-Gig deployments over HFC.
This paper will explore several considerations for upgrading the HFC network to 1.8 GHz FDD DOCSIS4.0 including a drop-in amplifier approach, intermediate upgrade steps, amplifier gains/tilts, and other operational aspects.