Lukas Sevcik

VŠB-Technical University of Ostrava

Video delivered over IP networks in real-time applications, which utilize RTP protocol over unreliable UDP such as videotelephony or live-streaming, is often prone to degradation caused by multiple sources. The most significant is the combined effect of video compression and its transmission over the communication channel. This paper analyzes the a...

Simultaneous wireless information and power transfer (SWIPT) has been utilized widely in wireless sensor networks (WSNs) to design systems that can be sustained by harvesting energy from the surrounding areas. In this study, we investigated the performance of the low-power energy harvesting (LPEH) WSN. We equipped each relay with a battery that con...

Due to the development of state-of-the-art fifth-generation communication (5G) and Internet-of-Things (IoT), the demands for capacity and throughput of wireless networks have increased significantly. As a promising solution for this, a radio access technique, namely, non-orthogonal multiple access (NOMA) has been investigated. Particularly, in this...

This paper proposes a novel method for video quality evaluation based on machine learning technique. The current research deals with the correct interpretation of objective video quality evaluation (Quality of Service – QoS) in relation to subjective end-user perception (Quality of Experience – QoE), typically expressed by mean opinion score (MOS)....

This paper deals with the impact of content on the perceived video quality evaluated using the subjective Absolute Category Rating (ACR) method. The assessment was conducted on eight types of video sequences with diverse content obtained from the SJTU dataset. The sequences were encoded at 5 different constant bitrates in two widely video compressi...

Video quality evaluation needs a combined approach that includes subjective and objective metrics, testing, and monitoring of the network. This paper deals with the novel approach of mapping quality of service (QoS) to quality of experience (QoE) using QoE metrics to determine user satisfaction limits, and applying QoS tools to provide the minimum...

The continuous development of fifth generation (5G) communication and Internet of Thing (IoT) inevitably necessitates more advanced systems that can satisfy the growing wireless data rate demand of future equipment. Device-to-Device (D2D) communication, whose performance is evaluated in terms of the overall throughput, energy efficiency (EE) and sp...

Relay communication, in which the relay forwards the signal received by a source to a destination, has a massive consideration in research, due to its ability to expand the coverage, increase the capacity, and reduce the power consumption. In this paper, we proposed and investigated energy harvesting (EH) based two-way half-duplex (TWHD) relaying s...

Relay communication, in which the relay forwards the signal received by a source to a destination, has a massive consideration in research, due to its ability to expand the coverage, increase the capacity, and reduce the power consumption. In this paper, we proposed and investigated energy harvesting (EH) based two-way half-duplex (TWHD) relaying s...

The number of active users using Voice over IP (VoIP) services has an increasing tendency. With an expanding number of users, there is also a rapid increase in the number of hackers interested in attacking the VoIP communication system. This paper aims at detecting malicious SIP traffic and also deals with the security of the VoIP architecture issu...

With the growth of QoE interest, IPTV providers need a method to control QoE. The paper describes the correlation between the results of objective and subjective methods in video quality assessment. The authors proposed the optimal mapping function for predictions of the subjective quality evaluation based on the objective evaluation to determine t...

In this paper, we evaluate and compare performance of multi-hop relaying (MR) protocols under impact of hardware impairments, in terms of outage probability (OP) and throughput (TP). By applying non-orthogonal multiple access (NOMA) technique at each hop, the end-to-end data rate/ throughput of the MR protocol can be enhanced, as compared with the...

In this paper, two energy harvesting policies deploying in cooperative non-orthogonal multiple access (NOMA) systems are considered. After period of wireless power transfer, the NOMA users including cell-edge and cell-center users simultaneously transmit the superposition coded symbols to the base station (BS). In the last time slot, the BS decodes...

In recent years, although non-orthogonal multiple access (NOMA) has shown its potentials thanks to its ability to enhance the performance of future wireless communication networks, a number of issues emerge related to the improvement of NOMA systems. In this work, we consider a half-duplex (HD) relaying cooperative NOMA network using decode-and-for...

Discovering periodic patterns in a customer transaction database is the task of identifying item- sets (sets of items or values) that periodically ap- pear in a sequence of transactions. Numerous meth- ods can identify patterns exhibiting a periodic behavior. Nonetheless, a problem of these traditional approaches is that the concept of periodic beh...

In the presence of an illegitimate user, we investigate the secrecy outage probability (SOP) of the optimal relay selection (ORS) networks by applying decode-and-forward (DnF) based full-duplex (FD) relaying mode. The closed-form expressions for the allocations of the end-to-end signal-to-interference-plus-noise ratio (SINR) in each wireless networ...

In this paper, the system performance analysis of a two-way decode and forward (DF) relaying network over the Rician fading environment under hardware impairment effect is proposed, analyzed and demonstrated. In this analysis, the analytical mathematical expressions of the achievable throughput, the outage probability, and ergodic capacity were pro...

In practice, full-duplex (FD) transmission mode not only helps extend the coverage but also lengthen network lifetime. In this paper, we develop wireless power supply policies, namely separated power (SP) and harvested power (HP) to propose a flexible architecture at the relay node in FD decode-and-forward (DF) relaying networks considering time sw...

The chapter deals with a speech emotion recognition system as a complex solution including a Czech speech database of emotion samples in a form of short sound records and the tool evaluating database samples by using subjective methods. The chapter also involves individual components of an emotion recognition system and shortly describes their func...

In the energy harvesting scheme, energy from the received information signal and co-channel interference (CCI) signals is scavenged by the self-power relay before it is used to amplify the received signal and finally transmit to the destination. Particularly, the closed-form outage probability expressions are evaluated for tractable performance ana...

In this paper, we analyse the performance analysis for two and three time slot transmission schemes (2TS and 3TS) for two-way Amplify-and-Forward (AF) relaying networks which are developed by wireless power and data transfer, where the energy harvesting (EH) relay node helps interchange information between two nodes. We derive the throughput and th...

The design of ID-based cryptography has received much attention from researchers. However, how to revoke the misbehavior/compromised user in ID-based public key cryptosystem becomes an important research issue. Recently, Tseng and Tsai proposed a novel public key cryptosystem called revocable ID-based public key cryptosystem (RIBE) to solve the rev...

In recent decades, high-utility itemset mining (HUIM) has emerging a critical research topic since the quantity and profit factors are both concerned to mine the high-utility itemsets (HUIs). Generally, data mining is commonly used to discover interesting and useful knowledge from massive data. It may, however, lead to privacy threats if private or...

High-utility itemset mining (HUIM) is a critical issue in recent years since it can be used to reveal the profitable products by considering both the quantity and profit factors instead of frequent itemset mining (FIM) of association rules (ARs). In this paper, an evolutionary algorithm is presented to efficiently mine high-utility itemsets (HUIs)...

Global System for Mobile communication (GSM) is the most widespread technology for mobile communications in the world and serving over 7 billion users. Since first publication of system documentation there has been notified a potential safety problem’s occurrence. Selected types of attacks, based on the analysis of the technical feasibility and the...

Nowadays, the interest in real-time services, like audio and video, is growing. These services are mostly transmitted over packet networks, which are based on IP protocol. It leads to analyses of these services and their behavior in such networks which are becoming more frequent. Video has become the significant part of all data traffic sent via IP...

The aim of this work is to bring complex view on video streaming service performance within IP-based networks. Video quality as a part of multimedia technology has a crucial role nowadays due to this increase. Since architecture of IP network has not been designed for real-time services like audio or video, there are many factors that can influence...

This paper brings a QoS (Quality of Service) assessment model which can estimate voice and video quality. Based on the proposed model, speech or video quality is computed with regard to congestion management QoS configuration in the network and its level of total utilization. The contribution of this paper lies in designing a new mathematical model...

Nowadays, there is a quickly growing demand for the transmission of voice, video and data over an IP based network. Multimedia, whether we are talking about broadcast, audio and video transmission and others, from a global perspective is growing exponentially with time. With incoming requests from users, new technologies for data transfer are conti...

This article deals with the impact of H.264/AVC and H.265/HEVC compression standards on the video quality for 4K resolution. In the first part a short characteristic of both compression standards is written. The second part focuses on the well-known objective metrics which were used for evaluating the video quality. In the third part the measuremen...

This article deals with the impact of H.265/HEVC and VP9 compression standards on the video quality for 4K resolution. In the first part a short characteristic of both compression standards is written. The second part focuses on the well-known objective metrics which were used for evaluating the video quality. In the third part the measurements and...

One of the weaknesses of the original Internet Protocol is that it lacks any sort of general purpose mechanism for ensuring the authenticity and privacy of data as it is passed over IP network. With the increased use of the Internet for critical applications, security enhancements were needed for IP. The aim of this paper is to investigate an impac...

This paper proposes a QoE (Quality of Experience) assessment model which can estimate voice and video quality. Based on the proposed model, speech or video quality is calculated with regard to policies applied for packet processing by routers and to the level of total network utilization. The contribution of this paper lies in designing a new compu...

This paper deals with QoS prediction of triple play services in IP networks. Based on our proposed model, speech or video quality can be calculated with regard to policies applied for packet processing by routers and to the level of total network utilization. This new simulating model was implemented in SW tool which enables networkers to predict o...

This paper deals with studying the effects of performance LTE network throughput for data traffic. Utilisation rate of networks has a significant impact on the quality parameters of triple play services. LTE network was simulated by the software module additionally implemented in a development environment MATLAB. Throughput model has been obtained...