Grade of service of a telephone exchange.

Title: Grade of service of a telephone exchange.
Authors: Lee, Lansun.
Date: 1967
Abstract: This project is concerned with the estimation of the grade of service given to the subscribers in a telephone exchange. The analytical models used are (a) the probability linear graph for lost calls and (b) the traffic flow graph for delayed calls. Both of these models are expressed in terms of the congestion functions of the sub-units of the switching system in the exchange. When these models are used, the engineering procedure of determining the quantity of equipment for the switching system in the exchange to satisfy the objective grade of service is simple. The switching system in the exchange may be divided into three major sub-units: the trunk groups, the switching network, and the common control. The congestion functions for these sub-units are discussed. The structure and the mode of operation for these sub-units are usually very complex, so that the congestion functions for these units can only be approximated. Thus, the overall grade of service estimated this way is only an approximation. Finally, the procedure of estimating the overall grade of service of an exchange is demonstrated by considering a simple hypothetical telephone switching system. The main contributions in this thesis are: (1) The traffic flow graph: This graph is used as the model for estimating the grade of service for delayed calls in an exchange. It can also be used for approximating the waiting time distribution for a given waiting system. (2) The equivalent trunk technique: This technique is shown to be reasonably accurate and simple for use in computing the trunk group congestion distribution when the trunk group is arranged in grading. (3) A method of approximating network blocking probability: This method can be used to approximate the blocking probability of any complex switching network. It is simple and inexpensive and produces reasonably accurate results. (4) Single linking stage network loaded with multitype of traffic: When some types of traffic require the service of more than one link at a time, the network for these types of traffic is blocked even if there are some idle links in the network. Extremely poor approximation will result if the usual assumption of independent busy links is used for calculating the blocking probability. In this thesis, such a network is analysed and a better approximation for computing the blocking probability is given. (5) General case approach for determining waiting time distribution for a single server delay system: Such a single server delay system is analysed. This aids one to the understanding of the congestion processes producing delays.
CollectionTh├Ęses, 1910 - 2010 // Theses, 1910 - 2010
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