TOPOLOGICAL PLANNING OF COMMUNICATION NETWORKS

In this paper, we concentrate on topological planning process of large-scale communication networks such as those used by telecom operators. Such networks are usually spread over large geographical area, and finding an optimal topology is very important part of the planning process. Network equipment used in such network is very expensive, and two connection points can be hundreds of kilometers apart. These networks, in most cases, form a backbone network of telecom operator, meaning that majority of traffic is carried through high-speed communication links of such network. Any cable cuts or equipment malfunctions could result in huge data losses. Therefore, such networks require high degree of availability and fault resistance, which must be considered during the planning process. Network topology providing fault resistance should offer at least two separate communication paths between any pair of network nodes. Most important issue in network topology planning is finding topology with lowest possible overall network price, while keeping all requirements (such as fault tolerance, availability, maximal number of hops, maximal blocking probability etc.) satisfied. Network design process can be divided into three stages. First step is making decisions about which network elements (nodes, existing edges) should be included in a backbone network (for instance, one of sub-problems appearing in this phase is facility location problem). Second step includes selection of network topology, so that all elements selected in first step will be interconnected satisfying given requirements. Last phase is used to determine node and link capacities needed for successful traffic transport as well as routings of traffic demands, including protection. Depending on technologies used in network, different routing and protection mechanisms, as well as specific topology models, can be used (e.g. SDH/WDM SHR, mesh, dual-homing etc.)

Algorithms applicable in the procedure of reading the working activities from tachocharts

Ključne informacije koje se vežu uz sigurnost cestovnog prijevoza robe i putnika vezane su uz tzv. radne aktivnosti vozača – podatke o trajanju vožnje, odmora i drugih zakonski definiranih aktivnosti tijekom radnog vremena. Praćenje radnih aktivnosti vozača bitna je stavka u logistici autoprijevozničkih tvrtki – osim kvalitetnijeg evidentiranja radnog vremena ti podaci služe i za otkrivanje eventualnih prekršaja i nepravilnosti u radu vozača. Za novoregistrirana vozila za prijevoz robe i putnika u RH vrijedi zakonska obveza ugradnje digitalnih tahografa. No, obzirom na prosječnu starost voznog parka autoprijevozničkih tvrtki u RH, još uvijek dominiraju ugrađeni analogni tahografi, koji podatke o radnim aktivnostima zapisuju na papirnate tahografske listiće. Preduvjet bilo kakve svrsishodne evidencije radnih aktivnosti jest digitalizacija tih podataka, odnosno očitavanje ključnih informacija s listića i prijenos na računalo. Ovim člankom predlaže se postupak za obradu i očitavanje podataka s tahografskih listića, opisuju algoritmi koje je moguće primijeniti u tom postupku i ukratko prezentira prateće programsko rješenje u sklopu kojeg su predloženi algoritmi implementirani.An important issue in the logistics of transport companies is efficient tracking of driver activities. It is directly related to public transport safety regulations, and therefore all companies have the obligation to provide required information. Since fleets of many Croatian transport companies include older vehicles equipped with analogue tachographs, digitalization of analogue tachocharts becomes highly important. This paper presents a process for tachochart digitalization and suggests few algorithms that were used in our analogue tachochart digitalization tool

Performance Comparison of Open Source and Commercial Computing Tools in Educational and Other Use — Scilab vs. MATLAB

In this paper, the authors compare the features and the overall performance of the two high-level numerical computing and modeling software environments: the freeware Scilab and commercially available industry-standard MATLAB. The motivation for the work emanated from the educational use of these tools at the college and university level, but with a perspective to their professional and scientific use as well. Their performance is tested by measuring the execution times of several combined-task benchmarks implemented as test functions, built upon nine common numerical tasks that are often found in programs for solving standard engineering problems. They include basic algebra and matrix calculations, signal generation, signal analysis, and storing and retrieving data to and from the hard disk drive. Although MATLAB outperforms Scilab in all the benchmarks except the disk file manipulations, in the presumed vectorization versions of the benchmarks, it is not for much. The overall performance of the freeware rival is very satisfactory, making it a good choice not only for educational use but also for scientific and professional purposes, especially when funding is critical

TOPOLOGICAL PLANNING OF COMMUNICATION NETWORKS

In this paper, we concentrate on topological planning process of large-scale communication networks such as those used by telecom operators. Such networks are usually spread over large geographical area, and finding an optimal topology is very important part of the planning process. Network equipment used in such network is very expensive, and two connection points can be hundreds of kilometers apart. These networks, in most cases, form a backbone network of telecom operator, meaning that majority of traffic is carried through high-speed communication links of such network. Any cable cuts or equipment malfunctions could result in huge data losses. Therefore, such networks require high degree of availability and fault resistance, which must be considered during the planning process. Network topology providing fault resistance should offer at least two separate communication paths between any pair of network nodes. Most important issue in network topology planning is finding topology with lowest possible overall network price, while keeping all requirements (such as fault tolerance, availability, maximal number of hops, maximal blocking probability etc.) satisfied. Network design process can be divided into three stages. First step is making decisions about which network elements (nodes, existing edges) should be included in a backbone network (for instance, one of sub-problems appearing in this phase is facility location problem). Second step includes selection of network topology, so that all elements selected in first step will be interconnected satisfying given requirements. Last phase is used to determine node and link capacities needed for successful traffic transport as well as routings of traffic demands, including protection. Depending on technologies used in network, different routing and protection mechanisms, as well as specific topology models, can be used (e.g. SDH/WDM SHR, mesh, dual-homing etc.)

Development of a Simple Tool for Audio Analysis on Mobile Android Platform

Svakim danom razvija se sve više aplikacija za „pametne“ mobilne uređaje bazirane na najpopularnijim mobilnim platformama – Android, iOS, Windows Phone i ostalima. Mobilni uređaji se sve učestalije primjenjuju i koriste za lakše obavljanje određenih zadaća. Kao takav priručni uređaj pokazuju sve veći tržišni potencijal. U ovom članku opisuje se tijek razvoja aplikacije za obradu zvuka na mobilnoj platformi zasnovanoj na operacijskom sustavu Android, namijenjene jednostavnoj analizi amplitudno-vremenske domene audiosignala. Programsko rješenje implementira tri jednostavne funkcije za obradu signala i vizualizaciju snimljenog uzorka. U članku se iznosi i kratak pregled izvedbe grafičko korisničkog sučelja bez kojeg ne bi bilo moguće upravljati ovom aplikacijom, te neke osnove digitalne obrade signala.Every day more applications for smartphone devices are being developed – on Android, iOS, Windows Phone, as well as other platforms. Mobile devices are being used for a rising number of everyday tasks, and as such convenient gadgets they are showing great market potential. This article is following the development of an application for sound editing on an Android mobile platform and deals with a simple analysis of an audio signal\u27s amplitude-time domain. It implements three simple functions for signal processing and recorded sample visualisation. The graphic interface, without which the control of this application would not be possible, is also being discussed, along with some basics of digital sound analysis

Izvedba programskog rješenja za očitavanje radnih aktivnosti vozača s digitalnih tahografskih kartica

Pitanje sigurnosti u javnom prijevozu i prometu roba i putnika oduvijek je bilo od iznimne važnosti. Direktna veza sigurnosti i sposobnosti vozača da efikasno i sigurno obave određene aktivnosti (vožnja) potaknula je razvoj uređaja koji bilježe radne aktivnosti mobilnih radnika, tzv. tahografe. U sva nova vozila za prijevoz roba i putnika tvornički se ugrađuju digitalni uređaji za spremanje informacija o radnim aktivnostima – digitalni tahografi. Način pohrane i dohvata podataka je standardiziran. Svakom vozaču se u ovlaštenoj agenciji izdaje digitalna kartica koju mora koristiti u vrijeme vožnje. Na nju se pohranjuju sve informacije i ona je ključan element kontrolnog sustava. Ovaj članak daje pregled dijela standarda za pohranu informacija na kartice vozača, a opisuju se i razvijena programska rješenja za očitavanje i interpretaciju podataka s kartica korištenjem standardnih čitača pametnih kartica

Heuristic algorithms for ring-based telecommunication networks design

Prstenaste telekomunikacijske mreže posjeduju svojstvo da mogu jednostavnim mehanizmima osigurati zaštitu prometa u slučaju kvarova. To ih je svojstvo učinilo vrlo čestim izborom u temeljnim mrežama u kojima je sprečavanje gubitka informacija u slučaju kvara od osobite važnosti. U postupku planiranja prstenastih mreža postoji niz specifičnih problema koje je potrebno riješiti. Ovim magistarskim radom daje se detaljan pregled postupka planiranja prstenastih mreža, te se ukazuje na osnovne probleme koji se javljaju u postupku. Problemi koji su obrađivani radom uključuju problem dimenzioniranja jednostavnih prstenova, problem određivanja prstenova na zadanim topologijama mreža, te problem prekrivanja mrežne topologije prstenastim strukturama. Problemi su sagledani analitički, te su naznačene neke mogućnosti rješavanja. Poseban naglasak stavljen je na primjenjivost rješenja u stvarnim mrežama – iako se model prstenastih mreža može primijeniti korištenjem različitih tehnoloških rješenja, u radu se stavlja naglasak na korištenje u SDH prijenosnim sustavima. Kao praktični dio rada implementirane su heurističke metode koje rješavaju spomenute probleme, te su analizirani dobiveni rezultati. Problemi dimenzioniranja prstenova i prekrivanja mrežne topologije prstenovima su također matematički formulirani, te je provedena optimizacija korištenjem matematičkog programiranja. Analizom rezultata zaključeno je da se iznesene metode mogu primijeniti u postupku planiranja prstenastih mreža. Praktični dio rada uključuje nekoliko razvijenih programskih alata koji se mogu koristiti u postupku planiranja prstenastih mreža – alati su korišteni u izvedbi nekih istraživačkih projekata te je time njihova funkcionalnost potvrđena na primjerima stvarnih mreža.Ring-based telecommunication networks can provide simple and effective traffic protection mechanisms in case of network failure. Because traffic protection is one of the most important issues in network design, ring-based networks are often used as parts of backbone networks. Several specific problems can arise within ring-based network design process. This work includes detailed overview of such planning process. Specifications of following problems are given: ring dimensioning problem, ring enumeration problem and problem of covering network with a subset of rings. All the problems are analyzed and heuristic algorithms that could solve them efficiently are proposed. Aspects of practical usage of proposed algorithms were studied, with special treatment for, in praxis, most often used, SDH transport systems. All algorithms were implemented within software tools developed as practical part of this work. Software tools were already used in some exploration projects and have shown their functionality on real-world network examples