Each day the Internet connects more people, increasing the need for transmitting secure information. One way to protect the data sent over the web is to conceal the relevant information inside a typical image, hiding the data from intruders. This paper proposes a hybrid heuristic, combining a genetic algorithm and the path relinking metaheuristic to efficiently solve this problem. Computational results show that the proposed algorithm outperforms the LSB (least significant bits) substitution technique, concerning the quality of solutions. In this way, the inclusion of a path relinking procedure can significantly improve the performance of a genetic algorithm for the problem considered.

Wireless technologies, developed within ICT at the end of XX, beginning of XXI century, are followed by adequate analytical support, which also made their implementation faster. At the beginning, their similarity with WiMAX concept launched the implementation of WiMAX systems in the scope of closely related research achievements. Therefore, this paper in a detailed and innovative way analyses possibility of using generalized analytical approaches (Cost 231, Erceg, SUI, ECC), developed primarily for GSM and UMTS systems engineering, in WiMAX coverage planning. Since direct usage of these approaches, in a global sense of applying, leads to inadmissible deviations of calculated parameters of relevance from homologue parameters present in physical reality, is made towards creating new models. Accordingly, authors are suggesting a new approach for evaluating applicability of existing empirical propagation models, using a coverage radius, or precisely, relative error of cell radius prediction. Great value of proposed approach is it's applicability during preliminary WiMAX system engineering and on drastically different types of topography (rural, urban and suburban), and therefore it's generalized nature. The fact that the same analytical frame, basically can be implemented globally, has provided the ground for taking a new step forward, opposite of using present partial solutions methodology, considering that these solutions, according to relevant literature are applicable for specific local topography only.

Wireless data services, boosted by the massive use of popular Internet-based services such as email, WWW, etc., wireless wideband networks capable of supporting mobile multimedia services have attracted increasing intention in last few years. An important requirement has been postulated for these wideband services — they cannot be substantially more expensive than the voice services offered today. This paper presents analysis of mobile wireless networks: HSPA and WiMAX made in order to compare multidimensional acceptance of investments in these technologies. Based in model in OPNET Modeler, the simulation and testing of different typical signals in these networks are made, where the Core network is taken as the same for both networks in order to neglect its influence on QoS results. The simulation results are than used as one dimension, QoS in multidimensional function of investment process. Also, business analysis of investments into these networks is also done, and 5-year investment value is taken as another dimension. The third dimension is taken as market acceptance of these technologies, which makes them cheaper or faster to implement. The result is multidimensional function which enables the operator to direct its investment process based on the same multidimensional space. It is shown that operator can decide to deploy one or another technologies based on its preferences.

We present a modular concept of e-voting system which ensures that registered voter can vote only once, while at the same time voters privacy is protected. This means that user identity can not be linked to a vote casted by the user. This is ensured by using random password distribution, where there is no trace in the system about the password that certain voter used for the voting session. Concept is simple, and is described using modules with basic assignments. Because of this, within this system, it is easy to recognize a place for any process defined in existing e-voting systems. This way, solution for password distribution given in this paper can be applied to different e-voting systems without many complicated modifications.

Migration to Next Generation Network (NGN) implies many challenges to traditional regulation. We can consider these in terms of regulated access to Next Generation Access Networks (NGA). In this paper we present a short overview of passive access (duct access, sub-loop unbundling, fibre unbundling) and wholesale active line access, which are essential for enabling competition.

This paper presents the use of coupled BEM/FEM method by the numeric calculations of protection current/potential distribution when the cathodic protection system with galvanic anodes is applied. Cathodic protection (CP) system is very efficient system for protection of underground metal object from corrosion. The most important phase by installing the CP system is to optimally and correctly defines the distribution of the protection current. There are many correlation related factors that influence the dimensioning of CP elements and the time of their design. The distribution of protection current/potential in systems of cathodic protection is governed by the Laplace equation, with the usage of corresponding predefined boundary conditions. Field data are obtained during the installation of the system and periodical field measurements during the exploitation of cathodic protection system with galvanic anodes. In this paper, acquired field data are compared to the values that were obtained using numerical calculations. Deviations between these data are negligible. Values of protection current/potential are most influenced by values of soil resistivity between anode and cathode surface.

This paper gives brief overview of possible methods for approximate locating of galvanic faults in cables with symmetrical copper pair cables as well as possible methods of repairing the same ones. The main focus is based on two principal methods of locating faults like the use of measuring instruments that run on the basis of bridge measuring methods and measuring instruments which use time domain impulse reflectometry.

This paper analyses qualitative and quantitative impact of large number twisted pairs transmitting ADSL signal, on one specific pair in the same cable. Change of pair capability to establish ADSL signal in respect to number of near active ADSL signals is observed. Information capacity is chosen as parameter of observed pair quality. At the beginning of this paper, simplified mathematical model of treated case is presented. After that, one pair during exploitation is analysed.

Maximal-Ratio Combiner (MRC) performances in fading channels have been of interest for a long time, which can be seen by a number of papers concerning this topic. Most of these papers treat Rayleigh, Nakagami-m, Hoyt, Rice or Weibull fading. This paper treats symbol error probability (SEP) performances of MRC in presence of generalized eta-mu fading. In this paper, we will present eta-mu fading model, and expressions for SEP of the L-branch MRC output. SEP will be treated for a broad class of modulation types and for non-coherent type of detection. SEP performances of the MRC will be presented via Monte Carlo simulations and theoretical expressions.

This paper analyses possibility of ADSL signal over long symmetrical copper-based twisted pair (about 7000 meters) establish. Got rate, its stability and possibility of its increase by effect on symmetrical copper-based pair primary parameters is analysed. Establishment of stable rate ADSL signal of enough value can be used for multimedia services providing through such ADSL system. Pair from 7100 meters long cable, with 0.4 millimetres conductor diameter polyethylene insulation and aluminium sheath is measured.

Importance of digitalization of AV (audio/video) signals, produced in TV studios, has been recognized long time ago, and in many countries, TV studios abandoned old analog transmission, leaving place for digital signal transmission. In Bosnia and Herzegovina, TV studios are still producing and broadcasting analog PAL signal, but according to recommendation, they should switch to DVB before 2012. Because of the actuality of this problem, the main idea of this paper was to make appropriate hardware and software solution for digitalization of PAL signal, acquired on the output of analog cameras or stored on tapes in studios, and its transmission over IP based network, together with application on client side. Using developed solutions on server and client sides, different types of compression and container formats are tested, in order to recommend TV stations the solution for producing digital AV signals with the best quality for end users, in future DVB network.

Like every other network protocols and technologies, VoIP implementation must be kept within certain limits that communication services are on expected and acceptable level. For H.323 VoIP networks, there are two areas of performance which interest network engineers. Signaling performance affects length of time necessary for call establishment between two H.323 terminals. RTP performance affects delay and overall clarity of voice signal during VoIP conversation. This paper gives an overview of RTP performance and shows how to use H.323 decoded data in order to evaluate signaling performance.

This paper researches changing of some basic parameters of symmetrical copper based twisted pair which is near the other twisted pair where active ADSL service exists. Analyzed parameters are: attenuation, signal to noise ratio, wideband noise and characteristic impedance. Analyzed subject is one pair in cable whose capacity is 100 x 2 x 0.4, with foamed polyethylene insulation and laminated polyethylene sheath. Existing ADSL service is sent through the different pairs in the observe cable and changes of the treated pair parameters are measured depending on the distance of the existing ADSL service from it. Obtained results are compared among themselves and with the parameters which are obtained in absence of ADSL service.

In this paper, an approach to techno-economical analysis of using PLC technology (power line communications), in broadband access networks, is presented. After short comparative analysis of relevant techno-economical attributes of different technological solutions for realization of broadband access network, basic elements of PLC solution techno-economical analysis, are more specific defined. Regarding proposed algorithm, which helps making better decision, the part of distribution power network in Sarajevo was analysed, in the purpose of implementing concrete PLC broadband access network, on that area. In this paper, we made our own models of PLC access networks, based on relevant statistical analysis and local topography. This approach enables number prediction of potential users, without losing reliability. All of this has the purpose creating more realistic presumption about cost efficiency in using PLC technology, on specific LV (low voltage) network.