Abstract

Hybrid fiber-coax (HFC) distribution systems provide a high bandwidth and cost-effective connection to the subscriber based on the use of fiber to a node location and subsequent transmission to the subscriber over coaxial cable. The resulting network is a physical point-to-multipoint system from the head-end to the subscriber, which is ideal for broadcast services, such as analog and digital television. Bidirectional telecommunications services can be provided on these networks by using a multiple-access protocol that allows each subscriber to access the head-end by using the return spectrum on the coaxial cable, which is typically in the range of 5–30 or 5–40 MHz. A number of multiple-access techniques, including timedivision multiple access (TDMA), frequency-division multiple access (FDMA), and code-division multiple access (CDMA), are being considered for use in HFC return systems. The requirements for the return-system multiple-access technique include the ability to dynamically assign bandwidth to a subscriber served by a single modem, high capacity, and the ability to provide a relatively error-free link for telecommunications services. In this paper we compare multiple-access schemes by taking into account the actual characteristics of HFC return systems.

© 1995 Optical Society of America