Digital loop carrier remote terminal having integrated digital subscriber plug-in line cards for multiplexing of telephone and broadband signals

Abstract

A fiber-based digital loop carrier (DLC) system provides multiplexed optical transport for telephone line circuits between a terminal in a central office and a remote terminal. The remote terminal performs the multiplexing and demultiplexing for interfacing channels on the fiber(s) to individual subscriber line circuits. To expand the capacity of DLC systems to carry broadband services, fibers are run from broadband terminations in the central office to the remote terminal. The remote terminal includes interfaces for coupling to optical fibers, for two-way telephone communications and for broadband communications. This terminal also includes a line card rack, for mounting various line cards and providing appropriate connections of the cards to the channels through the fiber interfaces. Some of the line cards provide normal telephone type service connections for one or more telephone lines. One or more of the line cards supports xDSL technology, for example Asymmetric Digital Subscriber Line (ADSL) type service. An ADSL line provides multiplexed transport of two-way telephone service signals, and one or more downstream and corresponding upstream digital broadband channel. The ADSL line card connects to one or more narrowband channels for telephone service and signaling communications and connects to a broadband channel, through backplane buses of the remote terminal. The ADSL line card also performs the digital encoding and multiplexing/demultiplexing of the narrowband and broadband communications for transport over a wire pair together with analog or ISDN type telephone signals.