Hybrid Fiber Coax, known as “HFC”, is the well-established cable access network architecture. As the name suggests, HFC consists of two separate media connecting a cable head-end to the subscriber. While the coax portion that connects to the subscriber gets most of the attention, the ‘heavy lifting’ is actually done by the fiber portion of the network. It’s here where we get the huge capacity necessary to deliver the content from and between cable head-ends, data centers, Internet PoPs and video server farms.
Why go ‘fiber deep’?
Today, cable MSOs are migrating to a “fiber deep” approach that pushes fiber all the way to the local access node. This approach aims to support the next-generation distributed access architecture (DAA) in which the PHY function is distributed from its traditional location in the head-end, out to the local access point: a process known as Remote PHY, or RPHY.
With RPHY comes the ability to increase the capacity in the access network and, since 2016, MSOs both large and small have been doing this using new technologies such as DOCSIS 3.1 and full duplex DOCSIS (FDX). These technologies enable higher data rates and, in the case of FDX, symmetric downstream and upstream connectivity speeds up to 10Gbps.
With these technologies, MSOs can continue to leverage the installed coax network making it more economical to compete with the high-speed services offered by fiber-based providers. However, these kinds of connections in the access (i.e., coax) network put enormous pressure on the metro core. Operating at these higher capacities, each subscriber is capable of consuming an entire wavelength, a situation that quickly exhausts capacity…