Energy Efficiency Optimization by Spectral Efficiency Maximization in 5G Networks

Energy and spectral efficiency are the mainchallenges in 5th generation of mobile cellular networks.In this paper, we propose an optimization algorithmto optimize the energy efficiency by maximizing thespectral efficiency. Our simulation results show a significantincrease in terms of spectral efficiency as well asenergy efficiency whenever the mobile user is connectedto a low power indoor base station. By applying theproposed algorithm, we show the network performanceimprovements up to 9 bit/s/Hz in spectral efficiency and20 Gbit/Joule increase in energy efficiency for the mobileuser served by the indoor base station rather than by theoutdoor base station

The Asymmetric Effect of Foreign Direct Investment on the Net Average Wages of Southeastern European Countries

There is a widespread belief in transition and growing economies that the relationship between FDI and wages is symmetrical. On the other hand, the problem of the nonlinear impact of FDI on wages has remained insufficiently explored. Therefore, this paper aims to determine whether there is an asymmetric effect of FDI stock on the net average wages within the eight SEE (Southeastern European countries) economies. We used the nonlinear autoregressive distributed lag (NARDL) and as well on the annual data for the period from 2000 to 2018. We found that there is an asymmetric impact of FDI stock on the net average wages of Bulgaria and Slovenia. In addition, we found that the symmetric effect is stronger compared to the asymmetric effect that the FDI stock has on the net average wages of Bulgaria, N. Macedonia, Montenegro, Serbia and Slovenia. Finally, we found that productivity, employment and education significantly affect solely Slovenia's net average wages

Partial frequency reuse for long term evolution

Zsfassung in dt. SpracheIn this thesis, I propose, develop, and analyze novel optimization techniques which solve resource allocation problems in partial frequency reuse (PFR) networks. In Long Term Evolution (LTE), multiple access in the downlink is established by Orthogonal Frequency Division Multiple Access (OFDMA). As a consequence, the cell edge users suffer from strong inter cell interference (ICI). This effect becomes even more severe, due to the low signal power which the cell edge users receive from the base station. Therefore, in this work, we have formulated algorithms that mitigate the ICI by optimizing the Radio Resource Allocation (RRA). An efficient use of radio resources (bandwidth and transmit power) is indispensable, since they are expensive and limited by spectrum licenses. For Inter Cell Interference (ICI) reduction, we define Partial Frequency Reuse (PFR) such that frequency reuse-1 is allocated to center-cell users and frequency reuse-3 is allocated to cell-edge users.Near the cell edges, the Orthogonal Frequency Division Multiplexing (OFDM) sub-carriers are allocated such that the users within do not use the same frequencies simultaneously (frequency reuse-3). We note that some bandwidth remains unused if the users spatial distribution is inhomogeneous in the cell. In this case, such a PFR scheme does not lead to an efficient utilization of radio resources. To mitigate this apparent inefficiency, I propose a novel bandwidth re-allocation scheme by maximizing the cell capacity density (i.e. achievable data rate per bandwidth per unit area). The proposed scheme re-allocates bandwidth from the cell edge to the center of the cell. The cell capacity density is a metric that represents the expected capacity per unit area for a randomly positioned user (uniformly distributed) in the cell. The network operators are interested in the achievable transmission rate per user. Therefore, we formulate the optimization problem as a maximization of the sum-rate under power and bandwidth constraints. We proved that this sum-rate maximization problem becomes convex for a fixed PFR bandwidth allocation scheme under a suitable additional power equality constraint. Using the Lagrangian, the analytical solutions are derived for the optimal power allocation, in a manner which is closely related to water-filling. Furthermore, we formulated two specific problems for the joint optimization of power and bandwidth allocation as convex geometric programs, i.e. the maximization of the minimum rate and the sum-power minimization, respectively.In PFR, a fundamental issue is to classify the users to the cell edge and center-cell regions. Two user classification schemes are investigated in this thesis in detail: The first classification scheme is based on the distance between the user and its serving base station.The second classification scheme is based on the user's Large-Scale Path-Loss Attenuation (LSPLA). Compared to the first classification scheme, the LSPLA scheme is proved to enhance the achievable user-rates.We have shown that the LSPLA classification scheme is successfully applicable to all discussed problems. Finally, we conclude that the LSPLA scheme allows to formulate spectrally efficient RRA algorithms in a form which can be implemented with fairly low numerical complexity.9

Kosovo’s Ground Flash Density and Protection of Transmission Lines of the Kosovo Power System from Atmospheric Discharges

In this paper is presented the protection of transmission power lines of the Kosovo Power System from atmospheric discharges, with the use of surge arresters. Atmospheric discharges represent one of the main causes of interruptions for the Kosovo Power System. In addition, the ground flash density for Kosovo is given. The transmission lines with the worst performance regarding atmospheric discharges are discussed in more detail and are presented recommendations about the surge arresters used to protect the system from these overvoltages. The data provided by the localized lightning system in Kosovo enable us to provide a detailed correlation of the reported outages of the Kosovo Power System and corresponding atmospheric discharges. Recommendations for protection in terms of surge arresters are given followed by subsequent dynamic simulations using MATLAB software

Using Record Level Encryption for Securing Information in Classified Information Systems

Information technology (IT) systems have great potential to improve the efficiency and methods of operation in each government organization, providing added convenience and flexibility. Currently, most of government law enforcement agencies have digitized their methods of work by advancing their user services. With this new approach, have come new threats, therefore, it is necessary to develop and implement standard policies to enhance information security and privacy on all classified information systems. In this paper a novel solution is presented for protection of information up to the record level encryption by applying the Advanced Encryption Standard (AES) algorithm using derived symmetric master key. The master key is unique per each record and is calculated in the client application. The uniqueness of the derived master key is assured by applying the exclusive or operation of the key of each record and the unique key of the client. Furthermore, this paper includes a critical approach on existing cryptographic methods and proposes additional methods to protect information, such us authentication, access control, and audit