Loop Evolution--Its Dynamics and Driving Forces

The basic concept of the present loop was initiated with the invention of the telephone. The loop plant has persistently been responsible for a major share of the total capital expenditures in the telephone network. It has also been the most reluctant part of the network to benefit from new technologies. Its evolution has been mostly confined to areas of distribution topologies, administration, and improvement in hardware. The main driving forces shaping the evolution of the loop plant in the past have been the cost effectiveness in loop subsystems and the interactive forces resulting from the evolution of the switching machines and the subscriber terminals. The emergence of new services, demanded by the subscribers as a result of socioeconomic evolution, and solicited by the common carriers with the promise of additional revenues and better utilization of "network resources," can be considered as a new dimension to the driving forces. Related new technologies are the vehicles enabling the actualization of the above driving forces. The main aim of this paper is to identify the interrelationships that exist between various elements of the loop system as well as assessing the nature of the impact which various evolutionary forces exert upon it. Logical arguments are offered to demonstrate that the loop evolution is pointing towards loop systems that provide more throughput at less cost and greater service flexibility. Terms and concepts are defined and introduced to support the above arguments. It is concluded that the short-term evolution of the loop plant will be dominated by the marriage of copper loops and electronics prior to the introduction of integrated fiber optics distribution systems.