Full Duplex DOCSIS over Active (N+X) Cable Networks

The recent advent of Full Duplex DOCSIS 3.1 has given cable operators an economic means to offer symmetric multi-gigabit access data rates. At its conception, Full Duplex DOCSIS was expected to only be deployed on fully passive cable plants (N+0). Compared to today's HFC networks that contain cascades of amplifiers to extend its reach, any N+0 deployment requires a significant increase in fiber penetration depth into the access network. In this paper, we will address the trade-offs of several options that allow deploying Full Duplex DOCSIS equipment on an active cable network, i.e., N+X with X>0. The options covered range from using "common" static diplexer-based amplifiers (with or without full duplex operation at the node), over switchable amplifiers that can reconfigure or even dynamically change their amplification characteristics, to amplifiers implementing echo cancellation that would be able to amplify the Full Duplex spectrum in both directions simultaneously.