No. 2 (2017)
Published:
2017-06-30
ARTICLES FROM THIS ISSUE
-
The New Metric and the New Software Tool for Determining QoS in the Short Messages Service in Mobile Networks
Abstract
With traveling professions and nomadic lifestyles on the increase there is a growing need for comprehensive mobile networking within the Next Generation Network, and the security, reliability and technical independency of the Short Message Service (SMS) is becoming more and more indispensable for business processes. Since competitiveness goes hand-in-hand with this business capability, and methods to determine the quality of this service are becoming equally indispensable. This paper presents possible methods to evaluate the “Completion Rate of SMS” and “End-to-End Delivery Time” and combinations of them (new metric in this paper). A software tool, QoSCalc(SMS), has been developed in collaboration with the authors in order to verify whether service providers are abiding by the Service Level Agreements. The tool has been tested in a real measurement environment and the results are presented graphically here and interpreted.
-
Modeling of Quality of Experience in No-Reference Model
Abstract
The key objective of no-reference (NR) visual metrics is to predict the end-user experience concerning remotely delivered video content. Rapidly increasing demand for easily accessible, high quality video material makes it crucial for service providers to test the user experience without the need for comparison with reference material. Nevertheless, the QoE measurement is not enough. The information about the source or error is very important as well. Therefore, the described system is based on calculating numerous dierent NR indicators, which are combined to provide the overall quality score. In this paper, more quality indicators than are used in the QoE calculation are described, since some of them detect specific errors. Such specific errors are dicult to include in a global QoE model but are important from the operation point of view.
-
The Microwave Sources for EPR Spectroscopy
Abstract
Rapid development of many scientific and technical disciplines, especially in material science and material engineering increases a demand for quick, accurate and cheap techniques of materials investigations. The EPR spectroscopy meets these requirements and it is used in many fields of science including biology, chemistry and physics. For proper work, the EPR spectrometer needs a microwave source, which are reviewed in this paper. Vacuum tubes as well as semiconductor generators are presented such as magnetron, klystron, traveling wave tube, backward wave oscillator, orotron, gyrotron, Gunn and IMPATT diodes. In this paper main advantages of gyrotron usage, such as stability and an increased spectral resolution in application to EPR spectroscopy is discussed. The most promising and reliable microwave source is suggested.
-
Quality Aspects in Digital Broadcasting and Webcasting Systems: Bitrate versus Loudness
Abstract
In this paper the quality aspects of bitrate and loudness in digital broadcasting and webcasting systems are examined. The authors discuss a survey concerning user preferences related with processing and managing audio content. The coding efficiency of a popular audio format is analyzed in the context of storing media. An objective study on a representative group of signal samples, as well as a subjective study of the perceived quality of real-time broadcasted and webcasted radio programs are performed.
-
Performance Comparison of Homogeneous and Heterogeneous 3D Wireless Sensor Networks
Abstract
Recent developments in wireless sensor networks include their applications in safety, medical monitoring, environment monitoring and many more. Limited battery energy and efficient data delivery are most considered constraints for sensor nodes. Depletion of node battery ceases functioning of the node. The network lifetime can be enhanced with the help of Multi-Layer protocol (ML-MAC). This paper presents a practical approach including 3-dimensional deployment of sensor nodes and analyzes two different types of networks –homogeneous and heterogeneous WSNs. To analyze various QoS parameters, two types of nodes are considered in a heterogeneous network. The performance of both the networks is compared through simulations. The results show that ML-MAC performs better for a 3D heterogeneous WSNs.
-
Self-organized Clustering for Improved Interference Mitigation in White Spaces
Abstract
In this paper a collaborative coexistence mechanism for white space base stations is proposed. We look at the case where these base stations operate in geographical areas where the density of used TV channels is such that only one channel is left for broadband access. We show how with cooperative closed loop control and a clustering strategy, it is possible to find feasible power assignments that provide a flexible and stable coverage solution. The framework under which we study our proposal is based on the IEEE 802.22 standard, which provides white space guidelines for applications in broadband access or machine-to-machine communications. We propose and evaluate a self-organized, collaborative power control and design strategy to enable effective coexistence of base stations under extreme bandwidth constraints. Finally, we also portray how proposed approach positively compares against others from different wireless access technologies.
-
Sharing Spectrum UE LTE and Air-Traffic Control Radars in 800 MHz Band
Abstract
The need to ensure LTE network coverage in sparsely populated and rural areas of Europe (ITU Region 1) has led to a massive use of 800 MHz band (band 20) with its good characteristics of radio wave propagation in LTE networks. However, the frequency band of 800 MHz called “digital dividend” in Region 1 is used on a primary basis not only by the terrestrial mobile service but also by air-traffic control radars (ATCR) that can lead to the creation of harmful interferences at the receivers’ input of ATCR. Such scenarios of mutual interferences became possible after granting licenses for LTE-800 frequencies to operators in such countries as Azerbaijan, Kazakhstan, Russia and other CIS countries, so this problem should be solved by operators at the deployment of LTE-800 networks in airports and areas close to them. So far, for such scenarios the ITU and CEPT have not formulated criteria for interference protection. The proposed protection criteria for receivers of ATCR from user devices’ interferences of LTE-800 networks were tested by experimental studies and can provide a solution to the electromagnetic compatibility (EMC) problem in a complex electromagnetic environment of modern airports and cross-order coordination of 800 MHz frequency bands in Region 1.
-
Battery Available Capacity Meter Built into an AC/DC Telecom Power Supply System
Abstract
The article describes the results of testing a Benning AC/DC power supply, with integrated NIT TBA-ST meter. Such integration enables accurate and energy-efficient measurements of available capacity of individual 48-voltage VRLA/AGM batteries with remote management possibilities. The full compliance with the requirements for telecommunication power systems, the great functionality, upgrade ability, immunity to user errors and the high accuracy of capacity and voltage measurement of battery monoblocks of proposed solution are presented.
-
A New Efficient Authenticated and Key Agreement Scheme for SIP Using Digital Signature Algorithm on Elliptic Curves
Abstract
Voice over Internet Protocol (VoIP) has been recently one of the more popular applications in Internet technology. It benefits lower cost of equipment, operation, and better integration with data applications than voice communications over telephone networks. However, the voice packets delivered over the Internet are not protected. The session initiation protocol (SIP) is widely used signaling protocol that controls communications on the Internet, typically using hypertext transport protocol (HTTP) digest authentication, which is vulnerable to many forms of attacks. This paper proposes a new secure authentication and key agreement scheme based on Digital Signature Algorithm (DSA) and Elliptic Curve Cryptography (ECC) named (ECDSA). Security analysis demonstrates that the proposed scheme can resist various attacks and it can be applied to authenticate the users with different SIP domains.
-
Mitigation of Scintillation Effects in WDM FSO System using Multibeam Technique
Abstract
Free Space Optical communication (FSO) has engrossed a large section of researchers in recent times due to its wide bandwidth, effortless deployment and immune links making it appropriate for communication purposes. This wireless optical technique requires clear and non-turbulent atmospheric conditions for efficient transmission. In this paper, authors aim at reducing the effect of turbulent atmospheric conditions like scintillation effect on FSO. Multibeam technique, which uses spatially diverse transmitters for transmission, has been used for increasing the achievable link distance of the FSO system. Parameters like quality factor and bit error rate have been used to check the received signal quality.
-
A New CPW-fed Patch Antenna for UWB Applications
Abstract
In this paper, the design and analysis of a compact size coplanar waveguide (CPW)-fed antenna for ultrawideband (UWB) applications is presented. The antenna has a compact size of 20×20×1.1 .5 .mm and provides a good impedance matching over the entire bandwidth of 3.2–14.3 GHz. The characteristics parameters, i.e. return loss, VSWR and radiation pattern, are analyzed using HFSS 11.0 software.
