Architecture and technology for the all-fiber loop

Digital loop carrier systems were designed as a replacement for the copper feeder pairs. The distribution portion of the loop remained unchanged. The copper Tl lines required for these systems were replaced with fiber multiplexer systems that provided inexpensive high-capacity feeder routes. Fiber feeder systems allowed a local exchange company (LEC) to increase the capacity by changing the electronics without adding more fiber to an often congested feeder route. The authors discuss the rationale for an all-fiber loop, LEC operations, and the optical technology and architecture used in the all-fiber loop