A new performance analysis model of local switching system with fuzzy control method for increasing call completion rate

Abstract

We study and present a new performance analysis model of the local switching system with three calling modes: incoming to line, line to line, and line outgoing. In M/M/R/R queueing model, only incoming tranks and outgoing trunks are regarded as customers and servers respectively. This model is suited for simplified toll switches. In our new model, lines are treated as either customers when calls are originated from or servers when calls are destinated to. Traditionally, the switching system of a telephone network is designed to be nearly non-blocking [1]. To achieve this goal, the switching engineers focus on the number of the interoffice trunks using Erlang B formula [8] based on the traffic measurement and forecast. According to the statistics, the call completion rate is about 75%, with 13% due to busy lines and 12% resulting from nonanswers. In order to increase the call completion rate, we propose a fuzzy control method. The simulation results show that our method will improve the call completion increase ratio by 17.2%. In this paper, we first introduce the problem and include related works of queueing models and the call completion rate for the local switching system. Next, we derive an analytic steady-state solution and a loss formula for the new performance analysis model. We propose a fuzzy control method to increase the call completion rate. In the fifth section, we present a simulation model and results. In our simulation model, by taking a terminating line of the local switching system as a server and an originating line as a customer, we simulate the behaviors of real traffic and make performance comparisons with the results by the Erlang B formula which is obtained directly from the M/M/R/R queueing model. We concluded that traffic carried by the simulation is larger than that by the Erlang B formula. In fact, the M/M/R/R model is a special case of our new model.