Institute of Electron Technology
Biblioteka Cyfrowa Instytutu Łączności / National Institute of Telecomunications: Digital LibraryNot a member yet
2189 research outputs found
Sort by
Orthogonal Harmonic Signals of the Generalized Class, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkTelecommunications transmission technologies with OFDM rely on orthogonal harmonic signal (OHS) systems. The criteria applicable to synthesizing OHS systems of the generalized class, including both classical signals and signals whose duration exceeds the orthogonality interval, have been considered. The problems of minimizing the effective width of the spectrum of the generalized class OHS have been solved. Estimates of the efficiency of the generalized class OHS have been given
LEES: a Hybrid Lightweight Elliptic ElGamal-Schnorr-Based Cryptography for Secure D2D Communications, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkDevice-to-device (D2D) communications in 5G networks will provide greater coverage, as devices will be acting as users or relays without any intermediate nodes. However, this arrangement poses specific security issues, such as rogue relays, and is susceptible to various types of attacks (impersonation, eavesdropping, denial-of-service), due to the fact that communication occurs directly. It is also recommended to send fewer control messages, due to authenticity- and secrecy related prevailing requirements in such scenarios. Issues related to IoT applications need to be taken into consideration as well, as IoT networks are inherently resource-constrained and susceptible to various attacks. Therefore, novel signcryption algorithms which combine encryption with digital signatures are required to provide secure 5G IoT D2D communication scenarios in order to protect user information and their data against attacks, without simultaneously increasing communication costs. In this paper, we propose LEES, a secure authentication scheme using public key encryption for secure D2D communications in 5G IoT networks. This lightweight solution is a hybrid of elliptic curve ElGamal-Schnorr algorithms. The proposed scheme is characterized by low requirements concerning computation cost, storage and network bandwidth, and is immune to security threats, thus meeting confidentiality, authenticity, integrity and non-repudiation-related criteria that are so critical for digital signature schemes. It may be used in any 5G IoT architectures requiring enhanced D2D security and performanc
Studying and Modeling the Performance of the TCM-STBC Systems in the Rayleigh Channel, Journal of Telecommunications and Information Technology, 2021, nr 1
Full text linkMultiple-input multiple-output (MIMO) systems will play an important role in future generations of wireless networks. Space-time block code (STBC) and space-time trellis code (STTC) are two techniques that may be used in multi-antenna radio systems. This paper aims, most importantly, to study the performance of STBC systems at different values of such parameters as spectral efficiency, matrix codes and constellations. A performance comparison between STBC and STTC schemes is performed. In order to show the efficiency of the system’s ability to communicate with uncoded and coded transmission structures over AWGN and Rayleigh channels, the trellis-coded modulation (TCM) is introduced. The results obtained show that the proposed TCM-STBC system model, using one and two receiving antennas, improves the performance of Rayleigh channel communication systems at 9.5 dB and 11.5 dB for a BER of 10−5
Phonetic Segmentation using a Wavelet-based Speech Cepstral Features and Sparse Representation Classifier, Journal of Telecommunications and Information Technology, 2021, nr 4
Full text linkSpeech segmentation is the process of dividing speech signal into distinct acoustic blocks that could be words, syllables or phonemes. Phonetic segmentation is about finding the exact boundaries for the different phonemes that composes a specific speech signal. This problem is crucial for many applications, i.e. automatic speech recognition (ASR). In this paper we propose a new model-based text independent phonetic segmentation method based on wavelet packet speech parametrization features and using the sparse representation classifier (SRC). Experiments were performed on two datasets, the first is an English one derived from TIMIT corpus, while the second is an Arabic one derived from the Arabic speech corpus. Results showed that the proposed wavelet packet de composition features outperform the MFCC features in speech segmentation task, in terms of both F1-score and R-measure on both datasets. Results also indicate that the SRC gives higher hit rate than the famous k-Nearest Neighbors (k-NN) classifier on TIMIT datase
COVID-19 Pandemic and Internet Traffic in Poland: Evidence from Selected Regional Networks, Journal of Telecommunications and Information Technology, 2021, nr 3
Full text linkThe COVID-19 pandemic has forced governments all over the world to impose lockdowns keeping citizens at home in order to limit the virus spread rate. The paper compares weekly traffic samples captured in the selected nodes of the network managed by NASK – National Research Institute during the pre-lockdown period, i.e. between January 27 and February 3, 2020, with those captured between March 30 and April 6, 2020, i.e. after the lockdown was announced. The presented results show changes in network traffic observed during the periods of time in question and illustrate the evolution in the popularity of top network service
Machine Learning-Based Small Cell Location Selection Process, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkIn this paper, the authors present an algorithm for determining the location of wireless network small cells in a dense urban environment. This algorithm uses machine learning, such as k-means clustering and spectral clustering, as well as a very accurate propagation channel created using the ray tracing method. The authors compared two approaches to the small cell location selection process – one based on the assumption that end terminals may be arbitrarily assigned to stations, and the other assuming that the assignment is based on the received signal power. The mean bitrate values are derived for comparing different scenarios. The results show an improvement compared with the baseline results. This paper concludes that machine learning algorithms may be useful in terms of small cell location selection and also for allocating users to small cell base station
Political and Economic Contexts of Implementing 5G in Poland and in Selected European Countries, Journal of Telecommunications and Information Technology, 2021, nr 2
Full text linkThe technology race to achieve the position of an economic leader is a phenomenon that has been taking place all over the world. The 5G technology has become a vital component of this race over the recent years. The technical capabilities it offers and the role it may play in the economy have become the subject of political debate and are at the very core of the “war for technology” between two superpowers: China and the United States. The European Union is aware of the fact that the position Europe enjoys on the international arena depends, to a large extent, on how quickly European countries will develop and implement 5G. Are individual European member states capable of seamlessly implementing the assumptions of strategies and plans concerned with the development of 5th generation technologies? Will the security of 5G networks be ensured in Europe? These are just some of the issues that are analyzed in this article with their economic and political context taken into consideration. A broader perspective is presented, with primary focus on the global geopolitical situation and on the conflict between China and the United States. The study was conducted by relying on an in-depth analysis of strategic state documents, reports drawn up by institutions tasked with implementing and monitoring the development of 5G technology, as well as literature on the subject and online resource
Cooperative Spectrum Sensing in Cognitive Radio Networks: A Survey on Machine Learning-based Methods, Journal of Telecommunications and Information Technology, 2020, nr 3
Full text linkThe continuous growth of demand experienced by wireless networks creates a spectrum availability challenge. Cognitive radio (CR) is a promising solution capable of overcoming spectrum scarcity. It is an intelligent radio technology that may be programmed and dynamically configured to avoid interference and congestion in cognitive radio networks (CRN). Spectrum sensing (SS) is a cognitive radio life cycle task aiming to detect spectrum holes. A number of innovative approaches are devised to monitor the spectrum and to determine when these holes are present. The purpose of this survey is to investigate some of these schemes which are constructed based on machine learning concepts and principles. In addition, this review aims to present a general classification of these machine learningbased scheme
Simulations of the MAC Layer in the LoRaWAN Networks, Journal of Telecommunications and Information Technology, 2020, nr 2
Full text linkThe Internet of Things is changing the approach to data transmission, protocol design and network services. The challenge faced by designers of IoT solutions is to determine the scalability of a given technology, with a particular emphasis placed on unlicensed frequency bandwidth (ISM) transmission in highly urbanized areas. Because the design and implementation of a wireless network for the Internet of Things, relying on each of the presented technologies, is expensive and time consuming, it must be preceded by a performance assessment based on computer simulations. The literature contains various approaches to modeling the mechanisms of the MAC layer of LoRa technology and to its implementation in LoRaWAN networks. The article provides an overview of major LoRa MAC network simulators. It presents and comments on the most important research results obtained by the authors of the aforementioned softwar
Performance Enhancement of Coherent Optical OFDM System Using LMS Algorithm, Journal of Telecommunications and Information Technology, 2020, nr 4
Full text linkInstability of the local oscillator causes phase noise – a phenomenon that is a disadvantage and is considered to be a major obstacle in the functioning of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. An attempt has been made in this paper to reduce the effects of common phase errors generated by phase noise. In this paper, a least mean square (LMS) based algorithm is proposed for estimation of phase noise. Using this proposed algorithm, the major problem of phase ambiguity caused by cycle slip is avoided and the bit error rate is greatly improved. Further, there is no requirement for modifying the frame structure of OFDM using this algorithm. A CO-OFDM system with the 8-PSK technique is used to implement the algorithm concerned. Furthermore, the algorithm, using the 8-PSK modulation technique, is analyzed and compared with the existing QPSK technique and with other algorithms. The investigations reveal that 8-PSK outperforms existing LMS algorithms using other techniques and significantly reduces the bit error rate