Valuation of the impacts of different factors on the reliability of a local public switched telephone network exchange

Abstract

TeJecommunicationls essentially required for modern civilization. The role of telecommunication in industry, agricl\lture, e-commerce, e-business, security services, social, economic and human modern activities is increasing day by day. With the increasing importance of telecommunication the reliability level of telecommunication system has assumed to be of great importance. For the improvement of the reliability of telecommunication system the identification of the factors affecting the system reliability 'is essentially required. It is also important to clearly evaluate the magnitude of the impacts of each factor so that the priority of reducing the role of the factors can be set. In order to do so this research work develops a mathematical model of evaluating the impact of each reliability component of 'Public Switched Telephone Network' (PSTN) system. The PSTN exchange records data regularly. These data do not directly provide the reliability values of each factor of the system. However, with some realistic 'assumption the develo~ed mathematical model evaluate the contribution of each factor towards the reliability of the PSTN system. The developed model is applied to two PSTN exchanges of Dhaka city. The salient features of , , different types of telephone calls are evaluated in terms of success rate", holding time, conversation time and the occurrence time of peak and minimum' call density. The performance of two exchanges are compared. The factors contributing towards the call f~ilure are identified. The magnitude of contribution of each factor is appropriately evaluated.i The reliability of i different types of calls are compared with the published data obtaineq ,from above two exchanges. i The outcome of this research will be a guideline for the telecommunication ~ystem planners and individual telecom operator to take necessary action ,plans to reduce failurds of telephone calls - i .', I to mctease system reliability and revenue 'earnings. The research will: also create awareness ""- among the subscribers to reduce failures of telephone calls.