Channel Modeling of the Return Channel in a Broadband Communication CATV Network

Many cable providers have been upgrading their cable TV network towards a bi-directional hybrid fibre/coax network not only delivering television but also telephony and interactive digital services. However; the performance of the return channel is of great concern because its 5 to 65 MHz frequency band suffers from ingress and impulsive noise. Measurements have been performed in a major Dutch cable plant to assess the return channel regarding bit-error rate and cell-loss. Results should provide input to the ongoing upstream transmission-format standardizations but also for channel modeling required to perform realistic system evaluations. This paper presents some measurement results, thereby focusing on impulsive noise concerning amplitude, duration, and density. It is concluded that, in contrast to the generally accepted view, not ingress noise but impulsive noise might be the most performance-limiting factor.