The advent of DOCSIS 4.0 Full Duplex (FDX) technology has arrived after several years of industry collaboration and the publication the DOCSIS 4.0 FDX specifications. Implementation of an FDX node reference design incorporating the remote PHY ASIC SoC has been initially evaluated in the Comcast labs. The key technology to enable simultaneous transmission and reception in the same spectrum requires real-time removal of the high-power cable plant reflections of the transmitted downstream signal from the low-power upstream signal received using “echo cancellation”.
The successful performance of this enabling technology demonstrates the potential for greatly increasing upstream throughput in an additional nearly 600 MHz of spectrum shared concurrently with the transmission of the downstream signal. Evaluations indicate increased spectral efficiency beyond the minimum performance requirements in the FDX specification. This paper will analyze the implied capacity limitations in the specs. A comparison to the measured performance is made which demonstrates exceeding these limits. This comparison will conclude that the performance limits in the FDX specification should be reexamined to update the expected efficiency gains enabled by full duplex echo cancellation technology as currently realized.