Jan Rozhon

Jan Rozhon
VŠB-Technical University of Ostrava · Department of Telecommunications

About

51
Publications
7,536
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221
Citations

Publications

Publications (51)
Article
Full-text available
This paper aims to describe and evaluate the proposed calibration model based on a neural network for post-processing of two essential meteorological parameters, namely near-surface air temperature (2 m) and 24 h accumulated precipitation. The main idea behind this work is to improve short-term (up to 3 days) forecasts delivered by a global numeric...
Article
Full-text available
With the increased number of Software-Defined Networking (SDN) installations, the data centers of large service providers are becoming more and more agile in terms of network performance efficiency and flexibility. While SDN is an active and obvious trend in a modern data center design, the implications and possibilities it carries for effective an...
Article
Full-text available
The technologies of the Internet of Things (IoT) have an increasing influence on our daily lives. The expansion of the IoT is associated with the growing number of IoT devices that are connected to the Internet. As the number of connected devices grows, the demand for speed and data volume is also greater. While most IoT network technologies use cl...
Article
Full-text available
In recent years, noticeable progress has been made in the development of quantum equipment, reflected through the number of successful demonstrations of Quantum Key Distribution (QKD) technology. Although they showcase the great achievements of QKD, many practical difficulties still need to be resolved. Inspired by the significant similarity betwee...
Article
This paper proposes a convolutional neural network (CNN) based encoder model to compress and code speech signal directly from raw input speech. Although the model can synthesize wideband speech by implicit bandwidth extension, narrowband is preferred for IP telephony and telecommunications purposes. The model takes time domain speech samples as inp...
Preprint
Full-text available
In recent years, noticeable progress has been made in the development of quantum equipment, reflected through the number of successful demonstrations of Quantum Key Distribution (QKD) technology. Although they showcase the great achievements of QKD, many practical difficulties still need to be resolved. Inspired by the significant similarity betwee...
Article
Full-text available
This paper describes different approaches for the face authentication from the features and classification abilities point of view. Authors compare two types of features - Histogram of Oriented Gradients (HOG) and Local Binary Patterns (LBP) including their combination. These parameters are classified using Multilayer Neural Network (MLNN) and Supp...
Conference Paper
The call quality is an important issue of the modern voice over IP (VoIP) networks. This is given by their inherent “best effort” nature and the fact that any packet can be delayed or lost along the transmission path. To ensure sufficient call quality from the customer’s point of view a multitude of approaches can be adopted, i.e. dynamic change of...
Article
Full-text available
The paper presents a system for monitoring and assessment the speech quality in the IP telephony infrastructures using modular probes. The probes are placed at key nodes in the network where aggregating packet loss data. The system dynamically measures speech quality and results are collected on a central server. For data analysis we applied four-s...
Conference Paper
Quantum Key Distribution (QKD), based on the laws of physics rather than the computational complexity of mathematical problems, provides an information-theoretically secure way of establishing symmetrical binary keys between two geographically distant users. This paper is oriented to the practical realization of QKD public channels which are usuall...
Conference Paper
This article discusses the impact of multilayer neural network parameters for speaker identification. The main task of speaker identification is to find a specific person in the known set of speakers. It means that the voice of an unknown speaker (wanted person) belongs to a group of reference speakers from the voice database. One of the requests w...
Chapter
The paper deals with an issue of the speech quality estimation in Voice over IP technology under packet loss. Packet loss is a major problem for real-time Internet applications, we applied four-state Markov model for modeling the impact of network impairments on speech quality, afterwards, the resilient back propagation (Rprop) algorithm was used t...
Article
A development of the tool meant to model and estimate the qualitative parameters of the speech and video transmission is the main aim of this paper. The influence of queuing techniques of individual network elements on the quality of service is explored and a model to predict this influence is created based on this information. By using this model...
Article
The paper deals with modelling network effects on the quality of speech. The packet loss modelling is based on the fourstate markov chain, afterwards, the resilient back-propagation (Rprop) algorithm is applied to train a neural network. The proposed solution allows for quick and precise speech quality estimation without the need to analyze the voi...
Article
Full-text available
In this paper, we present a software tool capable of predicting the final quality of triple play services by using the most common assessment metrics. The quality of speech and video in network environment is a growing concern of all the internet service providers to carry the multimedia traffic without the excessive delays and losses, which degrad...
Conference Paper
The paper presents a system for monitoring the speech quality in the IP telephony infrastructures using modular probes that are placed at key nodes in the network. The system is developed mainly within research of the Czech educational and scientific network, but the tool can generally be used in any IP telephone traffic. The system is capable of u...
Conference Paper
The quality of speech in network environment is a growing concern of all the companies and institutions, that migrated or are planning to migrate their voice communications to IP based technologies. This trend together with the increasing amount of Internet traffic in general poses a great challenge for network administration to be able to configur...
Conference Paper
The paper deals with presentation of the IVAS system within the 7FP EU INDECT project. The INDECT project aims at developing the tools for enhancing the security of citizens and protecting the confidentiality of recorded and stored information. It is a part of the Seventh Framework Programme of European Union. We participate in INDECT portal and th...
Conference Paper
The paper deals with performance measurement and assessment of SIP based network. The complex methodology for SIP benchmarking and performance testing based on IETF draft versions has been developed by our team so that the results coming from the measurement specified in this methodology could be compared platform independently. Our earliest implem...
Conference Paper
This paper deals with a benchmarking of SIP infrastructure and improves the methodology of SIP performance evaluation further to better fit into the design of the SIP testing platform, which is being designed in the VSB - Technical University of Ostrava. By separating registrations from calls, we were able to measure both cases without the need of...
Conference Paper
The paper deals with a speech quality monitoring tool which we have developed in accordance with PESQ (Perceptual Evaluation of Speech Quality) and is automatically running and calculating the MOS (Mean Opinion Score). Results are stored into database and used in a research project investigating how meteorological conditions influence the speech qu...
Conference Paper
This article deals with the impact of virtualization techniques on interactive delay-sensitive applications running in real-time, particularly IP telephony. Many institutions, organizations and home users often adopt the virtualized solutions for their safety, ease of administration and backup. Virtualization, which was chiefly the prerogative of c...
Conference Paper
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 q...
Conference Paper
The paper deals with an end-to-end delay model in IP network and the proposed model is focused on time sensitive applications based on Real Time Protocol, especially IP telephony. In order to predict overall delay of datagrams in IP network we need to express a contribution of all individual components influencing the delivery of signal on the tran...
Article
In the field of performance metrics and measurements of SIP (Session Initiation Protocol) Proxy and B2BUA (Back-to-Back User Agent) no standardized methodology has been presented yet. This gap results in a problematic determination of a hardware, the performance of which would be cost-effective and sufficient for the running the SIP Server in a giv...
Article
Full-text available
The paper deals with SW PBX Asterisk and with features supporting video calls but our primary object is not switching video calls but their automatic recording and replaying. Asterisk is open source telephone exchange which brings capability for audio and video calls but does not allow recording and playback of video files. We have implemented thes...
Article
This paper deals with a testing method suitable for SIP infrastructure. The performance testing is an issue of research and no standardized methodology has been adopted yet. We present the main ideas of the methodology that allows for testing the keystone of SIP based infrastructure – the SIP Server – in both SIP Proxy and B2BUA (Back to Back User...
Article
In the branch of performance testing of SIP based infrastructure no standardized methodology has been adopted yet. This is why we decided to develop a methodology suitable for testing and evaluating SIP server's performance. This paper should open a discussion about defining the parameters and methodology for benchmarking SIP based infrastructure,...
Article
This paper deals with a testing method suitable for SIP infrastructure. The performance testing is an issue of research and no standardized methodology has been adopted yet. We present the main ideas of our method that have been verified on open source software PBX Asterisk, as a representative of the well-known SIP solution. To be able to compare...
Article
This paper deals with techniques of measuring and assessment of the voice transmitted in IP networks and describes design of quality measurement, which can be used for Cisco Gateways. Cisco gateways send Calculated Planning Impairment Factor in every CDR (Call Detail Record). Our design is based on collection of CDR's, their storing into SQL d...
Article
Full-text available
This paper deals with techniques of measuring and assessment of the voice transmitted in IP networks and describes design of quality measurement, which can be used for Cisco Gateways. Cisco gateways send Calculated Planning Impairment Factor in every CDR (Call Detail Record). Our design is based on collection of CDR's, their storing into SQL d...
Conference Paper
Full-text available
This article discusses the use of the Voice Extensible Markup Language (VoiceXML, VXML) to create a complex voice menu in danger alert communication system. The system was created as a part of research at Department of Telecommunications at the VSB – Technical University of Ostrava. Creating a voice menu provides end-users more information about th...

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Projects

Project (1)
Project
Quantum Cybersecurity in 5G Networks (QUANTUM5) is a collaborative project of VSB - Technical University of Ostrava and University of Sarajevo supported by NATO SPS Programme (Science for Peace and Security Programme) in period 02/2021-01/2024. QUANTUM5 will practically demonstrate the application of Quantum Key Distribution (QKD) in 5G networking, providing sophisticated simulation tools and practical guidelines for further quantum technology convergence. Within the 5G network testbed installed on the campus of the VSB - Technical University in Ostrava, QUANTUM5 will integrate QKD technology to demonstrate secure 5G networking concepts such as network function virtualization (NFV) and software-defined networking (SDN) management. The goal is to examine the adaptive ways of network organization and management of the network through the assurance of the 5G high-speed networking and continuous provision of information-theoretical levels of security.