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Sensor networks, as a special subtype of wireless networks, consist of sets of wirelessly connected sensor nodes often placed in hard-to-reach environments. Therefore, it is expected that sensor nodes will not be powered from the power grid. Instead, sensor nodes have their own power sources, the replacement of which is often impractical and requires additional costs, so it is necessary to ensure minimum energy consumption. For that reason, the energy efficiency of wireless sensor networks used for monitoring environmental parameters is essential, especially in remote networking scenarios. In this paper, an overview of the latest research progress on wireless sensor networks based on LoRa was provided. Furthermore, analyses of energy consumption of sensor nodes used in agriculture to observe environmental parameters were conducted using the results of real measurements in the field, as well as simulations carried out based on collected data about real equipment. Optimization methods of energy consumption, in terms of choosing the appropriate data collection processes from the conducted field measurements, as well as the settings of network radio parameters imitating real conditions used in conducted simulations were highlighted. In the analyses, special emphasis was placed on choosing the optimal packet size. Unlike in other papers analyzing energy efficiency of LoRa communication, in this paper, it was proven that the adjustment of the transmission speed to the actual size of the packet is important for better energy efficiency of communication and that it can reduce energy consumption considerably. Moreover, in the paper, the contents of a packet that can be used in precision agriculture is suggested in order to prove that the 6-bit packet is sufficient for energy-efficient collection of parameters from the environment, in contrast to the 11-bit packets used in standard commercially available equipment. [ABSTRACT FROM AUTHOR]

In recent years a significant development of BASN (Body Area Sensor Networks) as a special subclass of WSN (Wireless Sensor Networks) has emerged. These networks have enabled a rapid development of telemedicine systems, which provide remote monitoring of patients and their vital parameters. The article gives a short overview of the BASN networks. Furthermore, a general system architecture of telemedicine systems is proposed. The proposed architecture includes a local sensory area, a communication network area and an institutional network area. It also provides the security and privacy of patient-related data. Furthermore, the article surveys some existing telemedicine systems. Finally, some current problems are explained and the directions for the future development of the telemedicine systems are given. [ABSTRACT FROM AUTHOR]

Aim Free web-based e-mail services are considered to have more security flaws than institutional ones, but they are frequently used among scientific researchers for professional communication. The aim of this study was to analyze frequency of usage of the insecure free e-mail services for professional communication among biomedical, economical and technical researchers, who published papers in one of three different journals: Croatian Medical Journal, Automatika and Economic Research. Methods Contact details of the authors who provided their e-mail address from the papers published in those three journals during one year period were collected. These e-mail addresses were collected from the electronic archive of the journals in question. The domains of all e-mail addresses were assessed and contacts were categorized into three groups according to the following types: world-wide known free web-based e-mail services, national Internet Service Provider (ISP) e-mail services, and institutional or corporate e-mail addresses. Results The proportion of authors using free web-based e-mail services, the least secure group type, was highest among biomedical researchers (17.8%) while every e-mail address collected from the technical journal belonged to the secured institutional e-mail group type. Conclusion It seems that all researchers from the technical scientific field and most of the researchers from the economical field value good security practice and use more secure systems for professional communication. High percentage of the biomedical researchers who use insecure e-mail services may mean that they need to be warned of the possible security disadvantages of those kinds of e-mail addresses. [ABSTRACT FROM AUTHOR]

IPv6 protocol, which should replace the actual IPv4 protocol, brings many new possibilities and improvements considering simplicity, routing speed, quality of service and security. In comparison to IPv4, IPv6 improves mechanisms for assuring a secure and confidential transfer of information. Despite these improvements, network security remains a very important issue since there are some security threats and attack types that can affect IPv6 network. This paper deals with security issues in IPv6 networks. Security improvements and extensions in the IPv6 protocol are described and explained. Also, security comparison to IPv4 is made. A description of the experimental IPv6 network and a description of tools used for security testing are presented in the paper. Security threats similar in IPv4 and IPv6 networks are described, and some security issues specific for IPv6 networks are also analysed. Different types of attacks in IPv6 networks are analysed and some suggestions for their avoidance are given. Considering security, especially problematic is the transition period of coexistence of both protocols. Because of that, security issues due to different transition mechanisms are analysed. Further, the paper studies firewalls in IPv6 networks. Implementation of firewalls in IPv6 networks and IPv6 specific firewall configurations are analysed. Different tests of firewalls are performed, and their results are analysed. Also, comparison with IPv4 firewalls is made. Some suggestions referring to proper deployment of firewalls are given. This paper also deals with detection of unauthorised intrusion. Different approaches to intrusion detection are explained and different types of intrusion detection systems are described. Suggestions for proper positioning of intrusion detection systems in the local area network are given. In absence of non-commercial intrusion detection systems with IPv6 support, some alternative possibilities of intrusion detection are explained. [Copyright &y& Elsevier]

Abstract In this paper, the importance of the predictive modelling process of broadband services adoption is described. A detailed overview of different analytical models used for prediction, i.e., fitting and forecasting processes of broadband services adoption are presented. Furthermore, a comparison of several analytical models commonly used for prediction of broadband adoption is conducted. In order to more accurately fit to the existing broadband adoption time series data, and to forecast the future broadband services adoption paths, the features of the most accurate common predictive models have been identified for different phases of broadband services adoption. Considering the given results, usage of additional models in the predictive modelling process is analyzed. The objective of these analyses is set to improve the accuracy of the existing predictive modelling process. The accuracy of the predictive modelling process using additional models is tested and compared in different phases of broadband adoption. The model which gives the most accurate results is identified. Finally, in order to enable the usage of this model within a whole broadband service life cycle, as well as to include a greater number of explanatory parameters in predictive modelling process, an enhanced predictive modelling process is proposed. [ABSTRACT FROM AUTHOR]

This study presents an optimisation of antenna arrays on the spherical surface with new elementary antenna distribution using the particle swarm optimisation method. Many distributions of antenna elements on the sphere are known and processed, like icosahedral, spiral, Leopardi and so on, but neither of them is optimal. In this study, optimisation of the antenna array includes radiation pattern optimisation in order to achieve a radiation pattern with a narrow main lobe and very low side lobes. Although distribution of antenna elements is not uniform, optimisation is performed for two planes using the average fitness function. Different applications of antenna arrays require different parameters and different optimisation/process control procedures, too. Spherical antenna arrays with optimised placement of elements are capable of producing a desired radiation pattern, providing electronic scan coverage over the entire sphere and satisfying requirements for many applications in different branches of communications. An antenna array analysed in this study is a spherical array with very low grating lobes and a very narrow main lobe, and it could be used in hemispherical scan coverage. [ABSTRACT FROM AUTHOR]

Abstract: The use of video-based applications has increased in recent years owing to the development of video technology as well as the widespread use of the Internet. Thus the evaluation of perceptual video quality has become very important and numerous video quality assessment (VQA) metrics have been developed over the past years. In this paper, we give a classification and a short review of objective VQA metrics, with a focus on the full reference metrics. With the aim of conducting a reliable test of the VQA metrics performances, we made two databases, each of them including 90 distorted video sequences. We carried out a subjective quality evaluation on these databases and the data were made available to the research community. Furthermore, we compared the performance of nine different, freely available, objective VQA metrics by using three different databases in different resolutions: LIVE Video Quality Database (768×432 resolution) and our two newly created databases for progressively scanned videos, i.e. ETFOS CIF Video Quality (ECVQ) database and ETFOS VGA Video Quality (EVVQ) database. Five different distortion types were used and the total number of 330 video sequences was evaluated. A comparison of metrics was done with respect to accuracy, monotonicity, stability, as well as complexity vs. accuracy criteria. The results show that the resolution, the content of the sequence and the distortion type have a significant influence on the performances of VQA metrics. Metrics that generally achieve a high correlation with subjective results for all databases and all distortion types are MOtion-based Video Integrity Evaluation (MOVIE) and Foveated Mean Squared Error (FMSE), but MOVIE has significantly higher complexity than FMSE. An exception is the distortion caused by IP transmission for which none of the analyzed metrics has shown satisfying accuracy and stability. [Copyright &y& Elsevier]