| 摘要 |
A national broadband network is based on fiber optic technology and scaled to cover a wide area, such as the contiguous lower United States. The network provides a high data rate interface for each subscriber and supports all the functions of the current telephone, Internet, and cable TV networks, with sufficient excess capacity to support future applications. Signals from several thousand subscribers are multiplexed on a single fiber pair connected to an intelligent switching center. Telephone central offices (COs) become multiplexing centers rather than switching centers, and the number of switching centers required to cover the nation is greatly reduced. Approximately 500 switching centers are interconnected by an optical backbone. Physical layer connections are established through the backbone between each pair of switching centers. Multiple ATM and/or STM connections are carried within each of these physical layer connections. The backbone is divided into optical network segments such that each segment covers approximately 1/8 of the contiguous United States. An integral number of space-wavelength channels are assigned to each connection through a network segment, with each of these connections containing many end-to-end subscriber connections. Space-wavelength channels are switched intact within the network segment, which simplifies signal processing and facilitates operation at extremely high data rates.
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