Economic Evaluation of Loop Feeder Relief Alternatives

The loop network, which is the transmission network between the local central office and the telephone subscribers, consists of a feeder network and a distribution network. The feeder network originates at the central office and fans out in a tree-like fashion into the area served by the central office. The distribution network branches from points along the feeder network and extends to individual streets and rights of way to reach the subscribers' locations. The boundary between feeder and distribution is not always well defined. Often, however, the feeder and distribution networks are joined by a feederdistribution interface. 277 Both the feeder and the distribution networks are facility networks. Together, they must supply the transmission facilities, which are usually called pairs* required to serve the subscribers. The feeder and distribution networks differ, however, in the way they are expanded to meet growing or otherwise changing subscriber requirements. The capacity of the feeder network is expanded in steps to meet growing pair requirements.2 The distribution network, however, is built to provide the capacity ultimately required in one step.3 This difference follows from a number of factors which are not discussed in this paper.f The concern here is, rather, that the feeder network requires periodic relief, i.e., addition or reconfiguration of facilities. This paper presents and discusses new methods associated with planning feeder relief. Much of what has been previously written about feeder relief has been concerned with sizing feeder capacity additions.2'4 This paper considers additional issues of feeder relief planning, specifically: (i) How to identify and evaluate relief plans which make optimum use of existing (i.e., previously placed) feeder facilities.