By Karthik Sundaresan & Jay Zhu, CableLabs; João Pedro Fernandes, NOS
DOCSIS® 3.1 is now largely deployed in the field, but so far it has been an Orthogonal Frequency Division Multiplexing (OFDM) Downstream only endeavor. Operators are beginning to test Upstream Orthogonal Frequency Division Multiple Access (OFDMA) and are discovering various intricacies in getting the US OFDMA to work robustly. We CableLabs and NOS, a cable operator in Portugal have been working together and have been focused on DOCSIS 3.1 OFDMA in general and collaborating on the Upstream Profile Management Application (PMA). Defining appropriate Upstream profiles for an OFDMA channel affects the stability of the modems on the channel and also the capacity realized. We implemented data collection agents through the CMTS CLI to collect Upstream RxMER for each CM, or on other CMTSs collect the data manually for each CM. US RxMER looks very different than the Downstream RxMER, due to the noise funneling characteristics on the HFC plant. NOS engineering and CableLabs collaborated on various US PMA algorithms and this paper will describe some of the new methodologies we have developed. The NOS operations team is doing a field trial with the US data collection and then configuring the profiles/IUC (interval usage code) generated by PMA on a live plant to understand the impact and behavior. This paper focuses on the lessons we have learnt from the DOCSIS 3.1 upstream field trial and production systems.