By Benny Lewandowski, Comcast; Greg Tresness, Arcom Digital, LLC.; Jon-En Wang, Comcast
Operators of cable networks are very familiar with the mandated requirements for monitoring signal leakage. In standard and mid-split deployments, leaks are discovered using a variety of techniques such as direct Quadrature Amplitude Modulation (QAM) measurement, direct detection of Orthogonal Frequency-Division Multiplexing (OFDM) signal components, and detection of Continuous Wave (CW) signals generated at the headend or Node Remote PHY Device (RPD) in the downstream direction. In high split deployments, leaks in the aeronautical band are discovered by monitoring the upstream for a specific test burst generated by the cable modem under control of the Cable Modem Termination System (CMTS.)
With the introduction of Full Duplex DOCSIS (FDX), some of the status quo practices for leakage detection will need to be changed due to the inherent differences between the traditional network and FDX which pushes the upstream (US) frequency up to 684 MHz. This paper explores several subjects related to detection and measurement of leakage in the FDX network. We will discuss how this will now necessitate leakage detection methods in both the downstream (DS) and US direction simultaneously in the aeronautical band, and we will discuss the potential benefit to perform additional Long-Term Evolution (LTE) band frequency measurements for upstream leakage when using full bandwidth FDX implementations.
We will additionally share lab test results demonstrating concurrent upstream and downstream leakage detection and we will propose a new test methodology for use in a controlled environment which will allow meter sensitivity testing for the new simultaneous upstream and downstream leakage detection.