By Daniel Howard, Broadcom Corporation
Mitigation of ingress, common path distortion (CPD) and impulse/burst noise is of great interest to cable operators. Advanced physical layer technologies such as frequency agility, enhanced error correction, ingress cancellation and FFT processing have created new tools for mitigation of impairments. Impairments can now be canceled, reduced or avoided by intelligent adapation of both signaling and system parameters. A detailed knowledge of RF impairments is required however, to both characterize the impairment and to determine the best mitigation strategy. In this paper, detailed models of common path distortion (CPD), ingress, and impulse/ burst noise are presented based on first principles and verified by plant measurements. The models were developed to optimize the detection, classification, and mitigation and/or avoidance of such impairments by advanced DOCSIS TDMA physical layer technology [1]. The result is higher upstream performance and capacity. A link between plant monitoring and communication system configuration is made that can significantly improve availability and overall plant maintenance. The approach is applicable to existing as well as deep fiber architectures.