Parametric Methods for Determining the Media Plane Quality of Service

The purpose of this thesis is to develop a reliable, convenient, and flexible parametric model that is able to estimate voice quality over mobile networks accurately and efficiently. The media plane contains the products of media gateways and media resource system for IP Multimedia Systems (IMS) solution. This study evaluates media quality on the media plane by the data collected directly from Media Gateway and data from audio samples through VoIP (Voice over Internet Protocol) applications. The methods applied for measuring the audio quality are intrusive methods - the Perceptual Evaluation of Speech Quality (PESQ) and the Perceptual Objective Listening Quality Assessment (POLQA). The parametric method developed in this thesis is based on the existing E-model method and is further developed in order to improve the accuracy and enable a detection of unwanted impairments in the media plane traffic. After this parametric method is developed, the correlation between the estimated MOS values from this method and the measured MOS values from PESQ and POLQA are studied to understand the accuracy of the results from this method. Afterwards, the performance of this method is also verified in this thesis. Furthermore, it is important that the method can be utilized in real live networks. An application is created by utilizing the parametric method to visualize the current Mean Opinion Score (MOS) value in a live network. MOS value can be easily estimated by packet loss parameters that are obtained from media gateways through this method. As the established parametric method is a simple non-linear regression equation, it not only reduces the time and power resource but also immediately visualizes speech quality in current live mobile networks. The method proves that it is very convenient for operators to notice immediately if the recently installed network software products can cause poor speech quality