Communications - Scientific Letters of the University of Zilina, 2008 (vol. 10), issue 4
Articles
Multimedia Quality as Perceived by the User
Jean-Yves Monfort, Klemens P. F. Adler, Hans-Wilhelm Gierlich, Joachim Pomy
Communications - Scientific Letters of the University of Zilina 2008, 10(4):5-10 | DOI: 10.26552/com.C.2008.4.5-10 
End-to-end voice quality as perceived by the user has always been of major concern to ETSI, the European Telecommunications Standards Institute and its Technical Committee STQ (Speech processing, Transmission and Quality aspects). Recent developments in telecommunications increasingly promote the introduction of new services, including wideband speech communication and multimedia. At the same advent the global telecommunication landscape is undergoing dramatic changes, such as the migration from traditional public network operators to internet (or NGN) service providers.This paper provides an insight into ETSI's activities for end-to-end multimedia...
How Do Non-Native Listeners Perceive Quality of Transmitted Voice?
Lubica Blaskova, Jan Holub
Communications - Scientific Letters of the University of Zilina 2008, 10(4):11-14 | DOI: 10.26552/com.C.2008.4.11-14
This paper describes the test methodology and results of speech transmission quality testing in the environment of non-native listeners; it means the communication language differs from the mother tongue of the test subjects. The tests were carried out based on ITU-T P.800 on a database of English speech samples affected by various coding distortions and background noise conditions. The subjects were pre-tested on their English proficiency. The subjective test results confirm a systematic and repeatable shift in subjective quality assessment performed by non-native listeners.
Standardization Paths for NGN IMS-Based Architecture
Tatiana Kovacikova, Pavol Segec, Michal Bruncko
Communications - Scientific Letters of the University of Zilina 2008, 10(4):15-18 | DOI: 10.26552/com.C.2008.4.15-18
Thanks to the rapid development of technology and increased availability of bandwidth, today more than ever, multiple services such as voice, video and data can be integrated and efficiently carried over a single infrastructure based on a packet network. An NGN (Next Generation Network) is able to deploy those services independently from underlying transport-related technologies, giving fixed or mobile users an access to different providers with the adequate QoS and security. In fact, it is the IMS (IP Multimedia Subsystem) inside the NGN that enables and drives efficient converged service offerings. IMS provides the framework for a common service...
Call Processing Language (CPL) - A Tool for Creation of Internet Telephony Services by the End User
Pavel Segec, Tatiana Kovacikova
Communications - Scientific Letters of the University of Zilina 2008, 10(4):19-22 | DOI: 10.26552/com.C.2008.4.19-22
Creation and programming new services are considered as crucial for the Internet telephony (IPT). A number of protocols have been defined for IPT, however, one of them - the Session Initiation Protocol (SIP) seems to be the most relevant thanks to its manifold features. The SIP offers many forms that can be used for programming new IPT services. One of them is to use the SIP baseline protocol mechanisms, the other - to define extensions to the baseline SIP protocol specification (defining new headers, new methods). Finally, the dedicated programming tools such as a Call Processing Language - SIP CPL, Common Gateway Interface - SIP CGI, SIP-servlets,...
A Comparative Study of Coverage Estimation and Quality of Service for DVB-H Urban Networks Using a Specialized RF Planning Software
Zafirios S. Pantelis, Stavros A. Kotsopoulos
Communications - Scientific Letters of the University of Zilina 2008, 10(4):23-28 | DOI: 10.26552/com.C.2008.4.23-28
The Digital Video Broadcasting - Handheld (DVB-H) standard is the ETSI standard for delivering broadcasting services of high data rates to handheld devices, under high mobility conditions. This paper will compare the different modulation techniques used by the DVB-H standard from the coverage point of view. The coverage estimation simulations have been made with a specialized RF planning tool using real Geographic Data for the metropolitan region of Athens. Thus, we will present a comparative study, of various planning factors like coverage percentage and location probability and compare them for the different modulation schemes used.
Wimax Performance Impacts in Multi-Cell Deployments
Yejian Chen, Hardy Halbauer, Frank Schaich
Communications - Scientific Letters of the University of Zilina 2008, 10(4):29-37 | DOI: 10.26552/com.C.2008.4.29-37
This paper presents the application of the multiple antenna schemes beamforming (BF) and Multiple Input Multiple Output (MIMO) in the broadband wireless access system WiMAX. The evaluation considers the competing performance demands on link robustness and peak data rate. Configurations for both uplink and downlink are discussed. We conclude that future wireless communications will rely on diverse and adaptive multiple antenna schemes to meet their requirements, in particular in the presence of strong co-channel interference.
Performance Modelling and Analysis of Passive Optical Networks for Poisson Traffic
J. S. Vardakas, V. G. Vassilakis, M. D. Logothetis
Communications - Scientific Letters of the University of Zilina 2008, 10(4):38-44 | DOI: 10.26552/com.C.2008.4.38-44
Passive Optical Networks (PONs) are the most important class of fiber-based access systems, capable of delivering services with numerous applications, such as high-definition video and video conferencing. In this paper we perform call-level performance analysis of the upstream direction in TDMA-based PONs and hybrid TDMA-WDM PONs. The proposed analysis is based on well-established recursive teletraffic models and leads to Call Blocking Probabilities determination. We consider the case where the optical access network accommodates multiple serviceclasses with Poisson arriving calls. The accuracy of the proposed analytical models is validated by simulation...
A Review of Slow- and Fast-Light Based on Stimulated Brillouin Scattering in Future Optical Communication Networks
Ronny Henker, Andrzej Wiatrek, Kai-Uwe Lauterbach, Markus Junker, Thomas Schneider, Max J. Ammann, Andreas T. Schwarzbacher
Communications - Scientific Letters of the University of Zilina 2008, 10(4):45-52 | DOI: 10.26552/com.C.2008.4.45-52
Slow- and Fast-Light has been investigated during the last years as a powerful tool to reduce and increase the group velocity of light pulses by light. It has enjoyed much recent interest because of the practical applications for telecommunication and information systems. Among these are optical signal processing, radio frequency-photonics, nonlinear optics and time domain spectroscopy. Furthermore, it can be seen as a key technology for optical delay lines, buffers, equalizers and synchronizers in packet switched networks. For a realization, there are different methods and material systems possible. Among them the nonlinear effect of stimulated Brillouin...
A Performance Analysis of the Dbms - MYSQL Vs POSTGRESQL
Svetlana Andjelic, Slobodan Obradovic, Branislav Gacesa
Communications - Scientific Letters of the University of Zilina 2008, 10(4):53-57 | DOI: 10.26552/com.C.2008.4.53-57
Modern communications among business subjects imply an exchange of a lot of data and information. To enhance that process in all its aspects, electronic data storing and processing is mandatory and enabled by an application of a DBMS (Date Base Managment System). This paper shows the performances analysis of the two most popular open source DBMSs - MySQL and PostgreSQL. First, some characteristics of these DBMSs are shortly described. Then the applied procedure of the performed testing is described. That is, the query (select, insert, delete and order by) execution times were measured for the both DBMSs mentioned, and the results shown in tabular and...
Investigation of Some Issues of Full Optical Multimedia Networks
Dusan Sabol, Jozef Dubovan, Miroslav Markovic, Milan Dado
Communications - Scientific Letters of the University of Zilina 2008, 10(4):58-63 | DOI: 10.26552/com.C.2008.4.58-63
Deployment of optical communication technologies into the core networks has allowed improvements in the transmission characteristics. Further penetration towards the end-user customers has brought online multimedia services. Increasing demand for a quality of service and new types of multimedia services challenges current state of the art technologies and drives not only coming technological trends. Recently emerging DPSK (Differential Phase Shift Keying) format is described and impact of OSNR (Optical Signal to Noise Ratio) level and laser linewidth on its performance is investigated in the environment of Virtual Photonics simulation software. Behavior...
Optical, Wired and Wireless Multimedia Service Access Solutions for Trend Setting Real Estates
Peter Mandl, P. Schrotter, E. Leitgeb
Communications - Scientific Letters of the University of Zilina 2008, 10(4):64-71 | DOI: 10.26552/com.C.2008.4.64-71
It is a well known fact that the value of real estates is raised tremendously by its connection to information technology services like Voice over IP (VoIP), IPTV, Video on Demand (VoD), basic Internet services and house-, security- and surveillance technologies. This paper will focus on different state of art methods to connect a real estate to the above mentioned services and will also discuss various inhouse cabling systems and related devices. Advantages and disadvantages between the miscellaneous combinations will be discussed.