After the independence of the Republic of Croatia was declared in 1991, the newly-formed national postal and telecommunications company HPT (Croatian Post and Telecommunications) found itself in an ...unenviable position. Croatia was in the group of countries at the forefront of telecommunications development in Europe. In 1990, it had only 17 telephone connections per 100 inhabitants. However, in the next eight years it moved closer to the European average, doubling its capacity to 35 telephone lines per 100 inhabitants by 1999. It did so despite the devastation of the Homeland War and the enormous damage suffered by its public telephone network. Croatia managed to negate the telecommunications blockade by finding alternative telecommunication routes, and then set out to build an efficient telephony and transmission system based on the use of fibre-optic cables and modern switching equipment. By the end of 1993, international switching hubs in Zagreb, Split, Rijeka, and Đakovo using AXE 10 technology were built, and the following year cities on the Croatian Adriatic coast were connected with cities in continental Croatia by fibre-optic cable. During this process, Croatia received its one-millionth telephone subscriber. Thanks to its participation in the TEL (Trans Europe Line) project, it became part of the telecommunication bridge between Eastern and Western Europe. In addition to the fixed public telephone network, it simultaneously developed a mobile public telephone network, first an analogue mobile network aptly named MOBITEL in 1991, and then the CRONET digital mobile network in 1996. These steps resulted in a significant increase in telephone traffic and the widespread availability of fixed and mobile telephone connections, which completely revolutionised public telephony in Croatia.
This book presents the fundamentals of wireless communications and services, explaining in detail what RF spectrum management is, why it is important, which are the authorities regulating the use of ...spectrum, and how is it managed and enforced at the international, regional and national levels. The book offers insights to the engineering, regulatory, economic, legal, management policy-making aspects involved. Real-world case studies are presented to depict the various approaches in different countries, and valuable lessons are drawn. The topics are addressed by engineers, advocates and economists employed by national and international spectrum regulators. The book is a tool that will allow the international regional and national regulators to better manage the RF spectrum, and will help operators and suppliers of wireless communications to better understand their regulators.
U Beogradu je 24, 25. i 26. novembra 2009. godine, u Sava centru, održan 17. telekomunikacioni forum TELFOR 2009, u organizaciji Društva za telekomunikacije – Beograd, „Telekom Srbija“ a. d., JP PTT ...saobraćaja „Srbija“, Elektrotehničkog fakulteta Univerziteta u Beogradu i IEEE Serbia & Montenegro ComSoc Chapter and Section. Telekomunikacioni forum TELFOR organizuje se sedamnaesti put kao domaći i regionalni godišnji skup stručnjaka koji rade u oblastima telekomunikacija i informacionih tehnologija. Učesnici su uglavnom telekomunikacioni inženjeri, ali i ekonomisti, pravnici, menadžeri, operatori i drugi. Na taj način TELFOR predstavlja forum u okviru kojeg se razmatraju sva relevantna pitanja telekomunikacija: tehnička, razvojna, regulatorna i ekonomska, pitanja proizvodnje opreme, usluga, servisa i funkcionisanja sistema.
Information, as one of the important factors of armed conflicts, greatly influences the physiognomy, the direction and the speed of the development of contemporary conflicts. It expresses the ...availability of knowledge and data necessary for successful command and control at all levels. Its availability reduces the uncertainty in military activity and enables a better assessment of the situation, as well as making relevant decisions in real time. In the paper, the Telecommunications and Information System (TkIS) of the Serbian Armed Forces (SAF) is looked at from several aspects, and the issue of the need for improvement of the existing system, imposed by constant development of information technologies, is being updated. The concept, purpose, structure and level of development of the TkIS are dealt with in the paper, particularly the level of development of the SAF TkIS and its cause-effect relation with the defense of the Republic of Serbia, with a focus on military defense. The aim of this paper is to examine the impact of the Serbian Armed Forces telecommunications and information system on the defense of the Republic of Serbia with the emphasis on military defense, and to point out the need for continuous improvement of the TkIS and continuous education, i.e. adequate and timely training of the personnel for its use for military defense. The importance of the work is in the analyzed state of the Serbian Telecommunications and Information System in relation to the needs of the military defense of the Republic of Serbia in the context of contemporary security challenges. / Информация, как один из важных факторов войны, оказывает большое влияние на форму, направление и скорость развития современных конфликтов. Она подразумевает владение знаниями и данными, необходимыми для успешного командования и управления на всех уровнях. Владение информацией снижает степень неизвестности в военном деле и способствует лучшей оценке ситуации, а также принятию соответствующих решений в реальном времени. В данной статье с разных аспектов представлена телекоммуникационная система (ТкИС) Вооруженных сил Республики Сербия и открывается вопрос о необходимости совершенствования существующей системы, что в свою очередь требует постоянное развитие информационных технологий. В работе описаны понятие, назначение, применение, структура и достигнутый уровень развития ТкИС. С особым вниманием были проанализированы уровень развития ТкИС ВС РС и причинно-следственные связи с обороной Республики Сербия, с упором на военную оборону. Цель данной работы заключается в представлении того, каким образом информационная и телекоммуникационная системы Вооруженных сил Республики Сербия могут влиять на оборону Республики Сербия, особенно на военную оборону, нам также хотелось обратить внимание на необходимость постоянного совершенствования и развития ТкИС, то есть, в организации соответствующей и своевременной подготовки персонала для нужд военной обороны. Значимость данной работы заключается в проведенном анализе состояния телекоммуникационной и информационной систем Вооруженных сил Республики Сербия и представлении реальных нужд военной обороны Республики Сербия в контексте современных вызовов безопасности. / Informacija, kao jedan od značajnih faktora oružane borbe, u velikoj meri utiče na fizionomiju, pravac i brzinu razvoja savremenih sukoba. Ona izražava raspoloživost znanjima i podacima potrebnim za uspešno komandovanje i rukovođenje na svim nivoima. Njenom raspoloživošću smanjuje se neizvesnost u vojnoj delatnosti i omogućava se bolja procena situacije, kao i donošenje svrsishodnih odluka u realnom vremenu. U radu se sa više aspekata sagledava telekomunikaciono-informacioni sistem (TkIS) Vojske Srbije i aktuelizuje pitanje potrebe unapređenja postojećeg sistema koje nameće neprestani razvoj informacionih tehnologija. U radu se navode pojam, namena, struktura i dostignuti stepen razvoja TkIS. Detaljno su analizirani stepen razvoja TkIS VS i uzročno-posledične veze sa odbranom Republike Srbije, sa težištem na vojnoj odbrani. Cilj rada jeste da se sagleda uticaj telekomunikaciono-informacionog sistema Vojske Srbije na odbranu Republike Srbije sa težištem na vojnoj odbrani, kao i da se ukaže na potrebu neprestanog usavršavanja TkIS i kontinuirane edukacije, odnosno adekvatne i pravovremene obuke kadra za njihovo korišćenje u vojnoodbrambene svrhe. Značaj rada ogleda se u analizi stanja telekomunikaciono-informacionog sistema Vojske Srbije u odnosu na potrebe vojne odbrane Republike Srbije u kontekstu savremenih bezbednosnih izazova.
Frakcioni račun je oblast matematičke analize koja se bavi izučavanjem i primenom izvoda i integrala proizvoljnog reda. Ovom teorijom bavili su se mnogi poznati matematičari među kojima su Ojler, ...Riman, Liuvil, Abel i Furije. Predloženo je više definicija za izračunavanje izvoda i integrala necelog reda. U ovom radu daje se pregled nekih predloženih definicija, kao i osnovne postavke frakcionog računa sa posebnim naglaskom na mogućnostima njegove primene u domenu modelovanja telekomunikacionog saobraćaja. Činjenica je da frakcioni račun poslednjih decenija nalazi sve veću primenu u raznim naučnim oblastima. Modeli zasnovani na frakcionom računu pokazali su se korisnim u fizici, mehanici, elektrotehnici, biohemiji, medicini, ekonomiji, teoriji verovatnoće. U ovom radu analizira se mogućnost primene frakcionog računa u modelovanju telekomunikacionog saobraćaja. Istraživanja pokazuju da se karakteristike telekomunikacionog saobraćaja na lokalnom i globalnom nivou u mreži, kao što su samosličnost i zavisnost u dugom opsegu, efikasnije mogu opisati pomoću frakcionog računa umesto konvencionalnih stohastičkih procesa. U radu su prikazani predloženi modeli zasnovani na frakcionom računu koji modeluju fenomene prisutne u savremenim telekomunikacionim mrežama. / Fractional calculus is a field of mathematical analysis concerned with research and application of derivatives and integrals of an arbitrary order. Many famous mathematicians studied the theory of fractional calculus such as Euler, Riemann, Liouville, Abel, Fourier and others. There are many proposed definitions for calculating derivatives and integrals of non-integer order. In this paper, several proposed definitions along with basic statements of fractional calculus are presented with an emphasis on a possibility of fractional calculus application in telecommunication traffic modelling. The fact is that fractional calculus is widely used in various scientific disciplines in recent decades. Models based on fractional calculus have proved to be very useful in physics, mechanics, electrical engineering, biochemistry, medicine, economy, and probability theory. This paper analyses a possibility of application of fractional calculus for modelling telecommunication traffic. Many research studies have shown that traffic characteristics at a local and global level, such as self-similarity and long range dependence, can efficiently be described by fractional calculus instead of using conventional stochastic processes. Some proposed models based on fractional calculus that describe phenomena present in modern telecommunication networks are presented in this paper. / Дробная производная (или производная дробного порядка) является обобщением математического понятия производной. Существует несколько разных способов обобщить это понятие, но все они совпадают с понятием обычной производной в случае натурального порядка. Данной проблемой занимались многие известные математики, среди которых Эйлер, Риман, Лиувилль, Абель и Фурье. В данной статье приведен обзор некоторых определений, наряду с основными положениями дробного исчисления, которые представлены с акцентом на возможность применения данного метода при моделировании телекоммуникационного трафика. Дело в том, что метод производной дробного порядка, нашел широкое применение в различных областях науки. Модели, основанные на данном методе, оказались востребованными в физике, механике, электротехнике, биохимии, медицине, экономике, а также в теории вероятности. В данной статье мы анализируем возможность применения метода производной дробного порядка для моделирования телекоммуникационного трафика. Исследования показывают, что характеристики телекоммуникационного трафика в сети на локальном и глобальном уровнях, а также самоподобие и зависимость в широком диапазоне, могут быть эффективно описаны с помощью метода дробной производной, вместо обычной модели мультипликативного стохастического каскада. В данной статье представлены предлагаемые модели, основанные на методе дробной производной, воспроизводящие явления, присутствующие в современных телекоммуникационных сетях.
This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing ...research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals.Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing.
his paper explores the relationship between customer loyalty and its seldom researched antecedents: relationship commitment,
relational equity and company image. The proposed conceptual model is ...tested with data gained from customers of mobile telephone operators. The results show that relationship commitment and relational equity have a statistically significant positive influence on customer loyalty. In addition, the results of hierarchical multiple regression analysis reveal that the number of different mobile operators a person uses is not related to customer loyalty when relationship commitment, relational equity and company image are included in the model. Drawing on the results, the paper offers implications for managing customer loyalty.
Digitalni multimedijalni sadržaj postaje zastupljeniji i sve više se razmenjuje putem računarskih mreža i javnih kanala (satelitske komunikacije, bežične mreže, internet, itd.) koji predstavljaju ...nebezbedne medijume za prenos informacija osetljive sadržine. Sve više na značaju dobijaju mehanizmi kriptološke zaštite slika i video sadržaja. Tradicionalni sistemi kriptografske obrade u sistemima za prenos ovih vrsta informacija garantuju visok stepen sigurnosti, ali i imaju svoje nedostatke - visoku cenu implementacije i znatno kašnjenje u prenosu podataka. Pomenuti nedostaci se prevazilaze primenom algoritama selektivnog šifrovanja. / Digital multimedia content is becoming widely used and increasingly exchanged over computer network and public channels (satelite, wireless networks, Internet, etc.) which is unsecured transmission media for ex changing that kind of information. Mechanisms made to encrypt image and video data are becoming more and more significant. Traditional cryptographic techniques can guarantee a high level of security but at the cost of expensive implementation and important transmission delays. These shortcomings can be exceeded using selective encryption algorithms. Introduction In traditional image and video content protection schemes, called fully layered, the whole content is first compressed. Then, the compressed bitstream is entirely encrypted using a standard cipher (DES - Data Encryption Algorithm, IDEA - International Data Encryption Algorithm, AES - Advanced Encryption Algorithm etc.). The specific characteristics of this kind of data, high-transmission rate with limited bandwidth, make standard encryption algorithms inadequate. Another limitation of traditional systems consists of altering the whole bitstream syntax which may disable some codec functionalities on the delivery site coder and decoder on the receiving site. Selective encryption is a new trend in image and video content protection. As its name says, it consists of encrypting only a subset of the data. The aim of selective encryption is to reduce the amount of data to encrypt while preserving a sufficient level of security. Theoretical foundation of selective encryption The first theoretical foundation of selective encryption was given indirectly by Claude Elwood Shannon in his work about communication theory of secrecy systems. It is well known that statistics for image and video data differ much from classical text data. Indeed, image and video data are strongly correlated and have strong spatial/temporal redundancy. Evaluation criteria for selective encryption algorithm performance evaluation We need to define a set of evaluation criteria that will help evaluating and comparing selective encryption algorithms. - Tunability - Visual degradation - Cryptographic security - Encryption ratio - Compression friendliness - Format compliance - Error tolerance Classification of selective encryption algorithms One possible classification of selective encryption algorithms is relative to when encryption is performed with respect to compression. This classification is adequate since it has intrinsic consequences on selective encryption algorithms behavior. We consider three classes of algorithms as follows: - Precompression - Incompression - Postcompression Overview of selective encryption algorithms In accordance with their precedently defined classification, selective encryption algorithms were compared, briefly described with advantages and disadvantages and their quality was assessed. Applications Selective encryption mechanisms became more and more important and can be applied in many different areas. Some potential application areas of this mechanism are: - Monitoring encrypted content - PDAs (PDA - Personal Digital Assistant), mobile phones, and other mobile terminals - Multiple encryptions - Transcodability/scalability of encrypted content Conclusion As we can see through foregoing analysis, we can notice that tunability, cryptographic security and error tolerance are the main unsatisfied criteria. Selective encryption algorithms based on static encryption parameters do not allow tunability. Tunability is a desirable property especially for content protection systems targeting different applications with different requirements in terms of security or visual degradation and different devices with different capabilities in terms of memory, computational power, or display capabilities. It is therefore appreciated to design a tunable selective encryption algorithm with dynamic encryption parameters.
Zastupljenost monopolističkih poduzeća varira od sektora do sektora.
Monopolistička poduzeća posebice su često zastupljena u onim sektorima koji su tradicionalno bili čvrsto vezani uz državu. Primjer ...za to su sektor
elektroenergetike i telekomunikacija. Stoga su danas, kada problem deregulacije posebno zaokuplja pozornost znanstvene i stručne javnosti, upravo sektori elektroenergetike i telekomunikacija često predmet razmatranja u pitanjima deregulacije. U radu se izlaže teorijska podloga na kojoj se temelji proces deregulacije gospodarstvene infrastrukture, a zatim se raspravlja o nekim praktičnim problemima kojii se javljuju u deregulaciji poduzeća u sektoru elektroenergetske odnosno i telekomunikacijska.
U radu se analizira povezanost odanosti potrošača s preduvjetima odanosti kao što su:
predanost u odnosu, relacijska pravednost i imidž poduzeća. Spomenuti elementi rijetko se
analiziraju, iako su ...važni kod stvaranja odanosti potrošača. Na temelju prethodnih istraživanja
pretpostavlja se pozitivna povezanost između odabranih elemenata od utjecaja na odanost
potrošača i same odanosti potrošača. Predloženi je konceptualni model provjeren na podacima
dobivenima od korisnika mobilnih operatera. Istraživanje pokazuje da postoji statistički
značajna pozitivna povezanost između predanosti u odnosu i relacijske pravednosti te odanosti
potrošača. S druge strane, imidž poduzeća statistički značajno ne pridonosi stvaranju odanosti
potrošača u mobilnim telekomunikacijama. Dodatno, rezultati dobiveni hijerarhijskom
multiplom regresijskom analizom dokazuju da broj različitih mobilnih operatera, koje osoba
koristi, nije povezan s odanosti potrošača kada se u model uključe predanost u odnosu,
relacijska pravednost i imidž poduzeća. Na temelju rezultata istraživanja, rad nudi prijedloge
za upravljanje odanosti potrošača.
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