Modelování kvality řeči v různých podmínkách síťového zabezpečení

Abstract

The master thesis is focused on evaluation of speech quality in various condition of network security. The beginning of the thesis is devoted to VoIP presentation and possibilities for how to secure the network connections with SRTP, TLS and IPSec. Linked to evaluation of speech according to the MOS scale. Discussing the factors influencing this assessment and the introduction of an evaluation mathematical model PESQ. The practical part is devoted to experiments and measurements at the workplace composed of two Asterisk PBX 11.7, where the system generates calls witch plays a record in English, with a dedicated transmission rate of 5 Mbit/s. Subsequent evaluations using statistical methods and an execution of regression analysis gaving rise to a variety of tools for processing the results in Matlab. The most important of these is a predictive mathematical model. This model is used to determine the performance limits of the transmission channel at the chosen type of security and the guaranteed value of the MOS. The results and achieved goals are evaluated at the end of the thesis.