5G networks are started to be deployed in urban areas in the dynamic spectrum sharing mode.Therefore, the analysis of Non-Line-of-Sight (NLOS) shadowing effects behind buildings of different heights becomes particularly important.The shadowing of GSM (900 MHz), UMTS (2100 MHz) and LTE (1800 MHz) technologies was investigated in the urban area.The results are examined by using the log-normal path loss model and four different stochastic equations, specifically: normal, log-normal, Rayleigh, and Nakagami.The results showed that the fluctuations of path losses in the urban area correspond to the model of lognormal path losses.However, path losses for individual buildings do not fit this model.Therefore, stochastic methods were used to analyse shadowing effects.A path loss model based on a differential stochastic equation was proposed.This model includes the following values: free space losses, path losses disturbance due to the shadowing effect, standard deviation σ, and a freely chosen parameter b.This model allows a very accurate estimate of the path losses of the three technologies.A clear correlation was observed between parameter b and standard deviation σ.

The evolving Internet of Things is based on such short-range technologies as Bluetooth, RFID, etc. However, one of the biggest drawbacks of these technologies is their vulnerabilities. This paper addresses the vulnerabilities of NFC technology which belong to the RFID class, namely, signal interception and jamming. Near Field Communication (NFC) defines a short-range wireless standard allowing data to be transmitted between two devices at a maximum distance of 20 cm (usually, 4 cm). NFC technology is widely used including banking and access control. Therefore, loss of data or jammed data on an NFC chip may result in a variety of extremely negative consequences for the users of this technology. The signal produced by the NFC scanner and tag is analyzed in this research. The maximum distance is investigated at which it is possible to record a signal of 13.56 MHz. Experiments show that data can be intercepted at a distance of up to 10 m by using an improvised passive antenna without any amplification or signal filtering circuits and by employing publicly available spectrum analyzers. Jamming of the signal was performed with a specially designed generator and another NFC reader. NFC signal attenuation results indicate that an attenuator with a very precise frequency is required. When another NFC scanner is used as the damper, the maximum distance at which the transmission between the scanner and the tag is successfully jammed is about 9 cm.

The planned in advance cyber-attacks cause the most damage for the users of the information systems. Such attacks can take a very long time, require considerable financial and human resources, and therefore, they can only be organized by large interest groups. Furthermore, current intrusion detection systems, intrusion prevention systems and intrusion response systems used to protect against cyber-attacks have several shortcomings. Such systems respond only to the attack itself when it is too late to take a preventive action and they are not suitable for detecting an attack in early stages when it is possible to block the attack and minimize the losses. Early detection requires detailed monitoring of network and system parameters to be able to accurately identify the early stages of the attack when it is still possible to kill the attack chain. In this paper, we propose to consider an attack chain consisting of nine stages. The method to detect early stage cyberattack based on the attack chain analysis using hardware implementation of logical filters is suggested. The performed experiment acknowledges the possibility to detect the attack in the early stages.

Increasing digitization together with the benefits has also brought a lot of problems related to the challenges in cyberspace. Due to the ongoing cyberattacks yearly increase, losses in sectors that are using Telecommunication and IT services are growing. The events of the past 10 years have shown that there are particularly dangerous incidents in the cyberspace, which are pre-planned, well-prepared and carried out by terrorist groups or even by some governments. Pre-planned cyber-attacks have some stages so it is possible to distinguish the early stages where attacks do not bring significant damage to data and information. This article examines the features of the attacks and their characteristics and is the first part of the study's generalization. There is proposed a method for early staged detection of such attacks using a number of the logical filters. Proposed methodology provides a network analysis structure, logical filter configuration and attack detection algorithms that enable the detection of network flow parameters that characterize potential attack vectors. The results of theoretical simulation have shown that proposed method is capable of determining early-staged cyberattacks.In the next paper, the logical mathematical model, an estimation of the sensitivity of such method and assessment of the probability of each initial stage will be presented. DOI: http://dx.doi.org/10.5755/j01.eie.24.3.20981

The paper presents measurement results of the GSM (900 MHz band), UMTS (2100 MHz band), and LTE (1800 MHz band) propagation path loss (PL) in the urban area behind the buildings of ten different heights. The results were compared with the 7 most popular models. It was found that the existing models approximate the experimental results with relatively large errors. The new model, which evaluates the path loss variation nature behind the buildings, is proposed. This new model shows good agreement with measurements for all three mobile technologies. The average relative error is less than 6.5 %.

During the last 5 - 10 years we see a boom of the development and use of unmanned air vehicles. The unmanned air vehicles are one of the fastest-growing and most-exciting technologies anywhere in the world. It is observed in both the military and the civilian field. However, a large number of vulnerabilities slow the development of this market. The purpose of this study is to examine military unmanned air vehicles vulnerabilities in battlefield conditions. The unmanned air vehicles and its systems market forecast is overviewed in this article. The forecasts are made to 2025. There are shown the market forecasts of the unmanned aircraft (civilian and military) trends. The comparison of these two markets is carried out. The comparison of unmanned aircraft and manned aircrafts markets development is also presented here. The unmanned air vehicles vulnerability classification and reasons of its losses in the military action zones are investigated also. It was found that most of the losses are due to technical failures. Significant places occupy losses due to shot down and pilots' errors. Great attention is paid to smart attacks against UAVs.

In this research paper, a signal propagation for microcells, based on building heights and distance from base station, is examined. The tests were carried out in an urban area. There were measured the signals' path losses from two mobile network base stations depending on buildings highs and distances to them. The "Anritsu Cell Master MT8212A" spectrum analyser was used for signal strength measurements. The results are compared with well-known models. Based on experiment results a new propagation model is proposed for the examined area.

The vulnerability of the device identifiers, such as IP and MAC addresses, IMEI and IMSI codes, etc. creates threat to the information security, integrity and reliability. One of the solutions of this threat is usage of Radio Frequency Fingerprinting (RFF) technology for identifying wireless devices based on their unique radiation “fingerprint” as opposed to their addresses or codes. In this work identification problems of mobile radio stations (from here in — mobile phones) are being analyzed and identification methodology for identifying them based on the mathematical processing of front and rear fronts is proposed. All of this provides new insight in the field of signal detection and identification, thus by using this method only the original data is received. The purpose of this work is identification of a mobile phone, working on the DCS (digital cellular service) frequency, based on the phone's radiated signal time characteristics.

In this research paper, 802.11 g/n signals non line-of-sight propagation inside the multifloor building is examined. Tests were carried out to assess the signal losses under these conditions. The D-Link and Trendnet wireless routers were used as signal sources in experiments. The measurements were carried out by fixing the routers in the fourth floor of the building. The signal levels were measured with the spectrum analyzer in the 2, 3, 4 (line-of-sight conditions) and 5 floors of the building. The results were compared with the Motley-Keenan model. A new improved model, which allows assessing these experimental results more accurately, is proposed in this paper.

In this research paper, 802.11g/n signal NLOS and LOS propagation inside the building with multi partitions is examined. The D-Link and Trendnet wireless routers were used as signal sources in experiments. The experiments were performed under two scenarios. The results were processed by means of statistical methods and compared with log-distance path losses and free space losses models. Strong waveguide in LOS propagation as well as some amplification effects that require further investigations have been determined. Some effects of 802.11g/n signal propagation through the homogeneous walls have been determined. A new model which allows to predict signal path losses under NLOS conditions when the signal is transmitted through the homogeneous walls is proposed. The results may be useful for indoor radio wave propagation modeling and analysis.

G. Cincikas, S. Japertas. Router Resource Management Research // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 6(122). - P. 79-82. The problem of resource management of the network node is analysed in the paper. It is offered to apply the L. Walras dynamic model for the solution of this problem. The stability of the resource management of network node in the cases of content and variable delay is investigated. It is expected that having applied the offered model of the system resource management, the system will be capable to change its state smoothly without reaching the critical one. Ill. 3, bibl. 7 (in English; abstracts in English and Lithuanian).

In this work the propagation of radio waves at 2.4 GHz in NLOS conditions has been studied. The study was carried out using two transmitters operating on different standards: 802.11g (D-Link) and 802.11n (TrendNet). The experiments were carried out under different scenarios in order to investigate the effect of the walls on signal propagation. Experimental results were processed using statistical methods and were compared with log-distance and free space models and with the network simulation programme Aerohive online planner results. A new signal prediction model, which allows predicting signal propagation depending on the number of walls, was created. In this work 802.11g and 802.11n standards were also compared. The results can be used to further investigate radio wave propagation in indoor NLOS conditions and in the development of wave propagation models.

S. Japertas, G. Cincikas, R. Sestaviskas. Company's Information and Telecommunication Networks Security Risk Assesment Algorithm // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 5(121). - P.33-36.Today the existing algorithms and instrumental security risk assessment tools mainly are dedicated to government institution or large-size companies. In this work there is proposed the risk assessment algorithm for medium and small companies. The algorithm consists of 8 steps. The methodology how to use this algorithm also is given there. The algorithm and methodology have been approved in the real small-size company. Ill. 2, bibl. 10 (in English; abstracts in English and Lithuanian).

The asymmetric cipher protocol, based on decomposition problem in matrix semiring M over semiring of natural numbers N is presented. The security of presented cipher protocol is based on matrix decomposition problem (MDP), which is linked to the problem of solution of multivariate polynomial system of equations. Compromitation of proposed scheme relies on the solution of system of multivariate polynomial system of equations over the semiring of natural numbers N. The security parameters are defined, security analysis and implementation is presented.

This paper deals with the image encryption scheme based on non-linear dynamic chaotic system in stream cipher architecture. The narrowing of the numbers domain interval to [0.2, 0.8] and a double precision floating point format to encode float numbers to binary format were used for pseudo random stream generator. The results of the NIST statistical test suite and security analysis are given. The results show very good cryptographic properties and high security. Key-Words: Image encryption, Non-linear chaotic dynamic system, Stream generator, Security analysis, Cryptography.

This article presents the analysis of using cryptographic methods for sensitive information interchanging. It is proposed the initiationprotocol for crypto graphical session that security is based on certain demands: the channel must exist, which is additional and save, thefunctioning of trusted third party must be and adversary can’t interfere between subjects interact and the third, i.e. trusted party. Thecryptography primitives are proposed, that allow realizing the second and third phases of initiation protocol. Besides, the analysis ofsecond and third protocol phases and prevention of cracking is done. That permits motivated involving of these phases on to initiationprotocol. Ill. 2, bibl. 5 (in Lithuanian; summaries in Lithuanian, English and Russian).