TheSLC 96Subscriber Loop Carrier System: Channel Bank

Abstract

The SLC@ 96 carrier system has been developed to bring digital capability to the local loop network, and ultimately it may be a component of a completely integrated digital network. It uses two unique channel banks: one located in the central office to interface to the local switching machine, and the other located remotely in the vicinity of a group of subscribers. The SLC 96 carrier can provide, through the use of different channel units, message telephone service, coin service, special services, and data services. For digital transmission, it interfaces to standard Tllines or optical fibers. The design is patterned after the D4 channel bank, and many of D4 carrier's channel units can be used in the SLC 96 carrier system. The resultant system has the versatility to serve both rapidly growing metropolitan, as well as rural, areas. Features that provide highly reliable service and easy maintenance have been included in the design of the system.

TheSLC 96Subscriber Loop Carrier System: The FiberSLCCarrier System

“…Light is produced in the "active" layer, a quaternary InGaAsP alloy whose composition is chosen to provide a bandgap characteristic of the The active layer is clad by higher bandgap n-and p-type InP layers, forming a double heterostructure. These cladding layers serve three purposes: (1) to provide efficient minority carrier (hole) injection into the active layer; (2) to confine the injected carriers to the active region, enhancing the radiative recombination rate; and (3) to serve as a transparent window for efficient transmission of the light through the top surface of the device. Details of the epitaxy and fabrication techniques are given elsewhere.'…”

“…To realize the desired system cost-effectiveness, the optical fiber had to be properly matched to the 1.3-~m LED/PIN. The basic fiber (1) parameters, which can be varied to optimize the transmission characteristics, are defined in Fig. 6.…”

“…The two sets of DSI streams from the two OLIUs are fed into a Line Switch Unit (LSU) that selects one of the sets and feeds it to the four TRUs. 1 Thus all multiplexing, demultiplexing, opticalto-electrical translations, and the lightguide medium are fully duplicated. This duplication protects against service interruptions due to any single failure.…”