By Tal Laufer & Jeroen Putzeys, ARRIS; Uffe Callesen, Stofa
This paper is an operational overview of one of the first Remote PHY deployments in the world, at a Danish operator – Stofa. Being an early adopter, the entire process of selecting the technology, planning the new network design, and deploying the products was an uncharted territory. Stofa and ARRIS, the selected vendor for the project, have learned many lessons from the experience, which are all detailed in this paper.
In addition, we have analyzed the benefits that the Remote PHY network upgrade has provided to the operators, including measured improvements in signal to noise ratio in the field and space and power saving in the head end.
The results we present demonstrate the great benefits transitioning to Remote PHY can achieve. First, there is a clear improvement in SNR values in the upstream (US) direction, which will allow Stofa to go to higher modulation orders using DOCSIS 3.1 US. In the downstream (DS) direction, results are less conclusive. The transition to R-PHY was accompanied with a move of DOCSIS D3.0 channels to higher part of the spectrum, which may have countered the improvement. In addition, some elements in the network like the drop cable were not replaced, and may affect the measured signal-to-noise ratio (SNR) at the cable modem (CM) side.
Second, we analyzed the space and power saving in the head end that resulted from the migration from the previous network architecture (Modular-CMTS) to Remote PHY. The analysis showed significant space savings – going from about 70 RU to 18 RU in the head end for the MAC core and network support, and less than half the power required in the head end for supporting these functions. In addition, the operational complexity is dramatically reduced, due to the major reduction in devices that need to be managed, and the automated management that is introduced. As part of the project, Stofa's ability to do proactive network management actions is greatly improved, as well as their ability to effectively grow their network and customer offering without any truck rolls or field work.
All these benefits will be reviewed in the paper, as well as the steps Stofa took in order to prepare for the deployment, and successfully deploy the new technology in the field, serving thousands of subscribers.