Jan Rozhon

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This paper deals with new proposal of a speech quality monitoring tool based on the perceptual evaluation of speech quality in accordance with ITU-T P.862 and its application in a research project investigating an impact of meteorological conditions on the speech quality in a GSM network. Every time we make a call using the GSM network the speech quality(More)
The paper deals with real time round trip measurement methodology. In contrast with probe-based methods, the new methodology tries to use an existing VoIP Operator infrastructure without any hardware or software installation into the infrastructure. The measurement is based on packet payload comparison and timestamp evaluation. The results of the(More)
The complexity and robustness of the currently used IP telephony infrastructures requires systematic monitoring of the network against security threats, where captured incidents are often used as a source of information for further research and analytical optimization of the monitored topologies. This article presents an analysis of IP telephony security(More)
The paper deals with speech quality monitoring system using probes placed on individual network nodes operating VoIP (Voice over Internet Protocol) services. The system is developed mainly within research of the Czech educational and scientific network, but the tool can be deployed generally in any VoIP infrastructure. In order to assess speech quality, an(More)
The paper deals with advanced techniques of automated configuring devices based on OpenWrt Linux distribution. In the paper, the overall concept and the architecture of the system is described, one part is devoted to the tool for automatic firmware building and the issues of key modules are also discussed. The solution has been built as a universal(More)
This paper deals with network performance simulation and quality of Triple-play services in IP networks. Based on our designed analytical model, the application has been created by means of which it is possible to predict qualitative parameters for QoS in IP networks, with regard to policies applied for packet processing by routers and with regard to the(More)
With Voice and Video over IP spreading to the new areas of mobile communications, the speech quality becomes a concern of high importance. Monitoring systems of various types are deployed massively in the infrastructure of all the providers. These systems provide the knowledge base for the providers to set the infrastructure of theirs properly and(More)