<title>Upstream HFC channel modeling and physical layer design</title>

Abstract

To facilitate economic development of robust upstream communications systems over hybrid fiber coax (HFC) plants, the characteristics of the HFC plant must be captured and presented in a form meaningful to communications systems/modem designers. These channel characteristics, along with performance goals for information rate and error rates, must be used to drive the selection of the appropriate choice of modulation and error control coding. This paper presents a set of parameters which characterize the upstream HFC cable plant in which upstream signaling is expected to perform. Furthermore, quantitative values for these parameters are presented which represent a reasonable impairment level for designers to accommodate; doing so will guarantee reliable communications with wide availability. Singe-carrier frequency and time division multiple access (F/TDMA) provides a low risk, high capacity approach which offers the best choice for upstream modulation over the characterized HFC system. This modulation technique is a mature technology; easily accommodates proven, effective mitigation techniques for combating the HFC upstream channel impairments; and is bandwidth efficient in the HFC channel. Frequency agility of the carrier, with both QPSK and 16-QAM modulation, multiple symbol rates, and flexible forward error control (FEC) coding and frame and preamble structure are advocated.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.