Data transmissions through HFC return channels

Abstract

The objective of this thesis is to investigate various methods to combat ingress noise in the Community Antenna Television (CATV) return channel. First upstream CATV channel models of Hybrid-Fiber Coaxing (HFC) networks are discussed paying particular attention to channel impairments of the return path. Two methods were then studied in depth to overcome ingress noise present in the network. One approach is to use Discrete Multitone (DMT) together with a bit-loading algorithm which avoids the frequency bands where ingress noise exists. The other approach is to use Tomlinson-Harashima Precoding (THP) together with an Interference Rejection Filter (IRF) that minimizes the signal distortion while whitens the ingress noise in the receiver side. We observe from the simulations that the performance of DMT bit-loading system is better than the THP-IRF system. We conclude that both the interference cancellation and DMT are efficient methods in overcoming ingress noise in the CATV return channel.