Feeder planning methods for digital loop carrier

This paper describes three new approaches to planning for digital loop carrier (DLC) in the exchange feeder loop network. Two of these are manual planning methods that are used to determine the most economical technology for satisfying facility shortages along a feeder route. Both are based on the concept of a distance-oriented crossover point beyond which DLC is the economic relief technology. One of the methods uses a global crossover point for alt routes, and the other uses a route-specific crossover point The third approach is a mechanized toot, the Pair Gain Planning (PGP) program. PGP, which is implemented as a module within the existing Bell System loop planning system, first identifies the appropriate technology for relief and then synthesizes a specific DLC implementation plan. A discussion of system performance and projected Bell System applications of the various methods is included.