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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Paslaugų teikimo mobilaus ryšio tinkluose modeliavimas / Modelling Of Services In Mobile System Communication

Serbenta, Evaldas 31 May 2006 (has links)
In this master paper are analyzed services which are offered in GSM network. There is review of offered possibilities and its resources. There have been created model which imitates mass following service in mobile network. There have been made research by this created tool which quantitatively evaluates general quantity of update and paging procedures depending on size of location area and type of subscriber. There have been noticed some tendencies which depend on: paging period, size of location area and the ratio of transfered mesages by location updating and by paging procedures.
42

Vietos nustatymui naudojamų metodų įtaka GSM tinklo apkrautumui / The Impact of Location Methods on GSM Network Load

Diglys, Darius 01 June 2006 (has links)
This work investigates the problem of location methods putting load on GSM network. The work carried out covers analysis of various location methods, identification of network nodes and datapaths that are involved in getting location data from GSM network. It is shown that methods can generally be divided into two groups: those that use special devices to locate and then transfer results via GSM network and those that use GSM network for positioning. The impact of first group on GSM network load is limited to the time of data transfer time that depends on the coding scheme used, data transfer channels allocated and size of location data. The impact of second group depends on algorithm used. Analysis and experiments carried out using custom GSM network emulator show that standard “Provide Subscriber Info” based algorithm requires mandatory update of location information within GSM network using either SMS or preempted call setup that both require radio resources. Usage of “Customer Trace” algorithm for self-location applications is proposed to save radio resources. Additional benefits of this algorithm include usage of timing advance and signal strength information from “Customer Trace” data to increase the accuracy of location within current GSM network infrastructure.
43

Remote news reports over digital cellular networks

Neale, Jason January 1999 (has links)
No description available.
44

Διερεύνηση παραμέτρων και υλοποίηση αλγορίθμου για τον κυψελοειδή σχεδιασμό (cell planning) ψηφιακών ασυρμάτων κέντρων δεύτερης και τρίτης γεννιάς [sic]

Παπαιωάννου, Χαράλαμπος 08 January 2013 (has links)
Σε αυτή την εργασία πρώτα από όλα αναλύουμε τις βασικές έννοιες και αρχές μιας κυψελοειδούς σχεδίασης, καθώς και σημαντικές λειτουργίες που εκτελούνται σε ένα κυψελωτό σύστημα. Επίσης παρουσιάζουμε βασικές αρχές της μοντελοποίησης ενός ασύρματου καναλιού. Δίνουμε μεγάλη έμφαση σε όλα τα παραπάνω ,για να μπορέσει ο αναγνώστης να κατανοήσει τη λογική με την οποία στη συνέχεια κατασκευάζουμε τους αλγόριθμους που βοηθάνε στον κυψελοειδή σχεδιασμό ψηφιακών ασύρματων κέντρων δεύτερης και τρίτης γενιάς. Αφού αναλύσουμε τον τρόπο υλοποίησης των αλγορίθμων, στη συνέχεια τους χρησιμοποιούμε για τον κυψελοειδή σχεδιασμό του δήμου Πατρέων χρησιμοποιώντας την τεχνολογία gsm για να κατανοήσουμε καλύτερα τη λειτουργία τους. Στην ουσία δηλαδή αφού έχουμε κατασκευάσει τους αλγόριθμούς μας, οι οποίοι μπορούν αναλόγως των παραμέτρων που θα τους βάλουμε να χρησιμοποιηθούν για δίκτυα δεύτερης και τρίτης γενιάς, τους βάζουμε τις παραμέτρους του gsm και εκτελούμε μία προσομοίωση για την περιοχή του δήμου Πατρέων. Για να μπορέσουμε να κατανοήσουμε τις παραμέτρους του gsm αφιερώνουμε μία ενότητα στην περιγραφή της αρχιτεκτονικής του. Συνεπώς στο τέλος της εργασίας ο αναγνώστης είναι σε θέση να κατανοήσει πλήρως την διαδικασία που πρέπει κάποιος να εξακολουθήσει για να υλοποιήσει μια κυψελοειδής σχεδίαση σε οποιαδήποτε γεωγραφική περιοχή, χρησιμοποιώντας οποιαδήποτε τεχνολογία 2ης και 3ης γενιάς με τη βοήθεια των αλγορίθμων που κατασκευάσαμε. / -
45

Detection and Classification of Interference in Mobile Communication Systems / Detektion och klassificering av störningar i mobila kommunikationssystem

Ring, Christoffer January 2015 (has links)
The usage of wireless technology has in the past decade vastly increased and it continues to do so as well. Because of this, we become more and more reliant on this considerably fragile technology. Wireless technology, which uses radio waves to transmit data from one point to another can easily be interfered by radio jammers. This thesis work is about the detection and classification of the interference that is produced by jammers over the Global System for Mobile Communications (GSM) air interface. A typical GSM jammer that can be found on the Internet is analyzed but also more advanced GSM jammers are analyzed. The GSM standard is analyzed to find vulnerabilities that a jammer can take advantage of. The result is an interference detector that can be used to detect and classify interference over the GSM networks. The detector is constructed with an Universal Software Radio Peripheral (USRP) but is also portable to other software-defined radio (SDR) platforms.
46

Secure tracking system for next generation CIT products

Kosmas, Christopher William January 2014 (has links)
The Cash in Transit (CIT) industry demands reliable and innovative products from its suppliers to ensure safety and reliability within the industry. Product innovation has been directed at a bespoke tracking system for the Cash in Transit industry, which can meet its stringent requirements and excel above the capabilities of standard, readily available tracking systems. The presented research has investigated the state of the art in tracking and localisation systems and has highlighted Wi-Fi as a potential novel Cash in Transit tracking solution. With research into 2.4GHz Wi-Fi and the effects in a CIT environment, the technology has been understood and demonstrated in terms of its advantages and weaknesses when applied to CIT. The research has shown that 2.4GHz Wi-Fi is a novel and viable solution for both wide area tracking and localised tracking of a Cash in Transit security box by testing innovative ways of detecting theft using 2.4GHz Wi-Fi in a set of specific real-world scenarios. An embedded tracking system was developed and a thorough evaluation undertaken using a series of practical usage scenarios. The results show the proposed tracking capability is very effective and ready for initial effective use within a Cash in Transit security box.
47

Monitoring GSM sítě / Monitoring of GSM network

Trávníček, Tomáš January 2008 (has links)
This master’s thesis is focused on problems of monitoring GSM network using a mobile phone. Problems are analyzed on a theoretic basis with a description of available network parameters. Then the thesis offers a description of existing application environments providing a user with given data about the network. The main part of this work describes a development of application compiling queue data from mobile network and GPS, and creates output data illustrating signal strength in selected areas. The work also includes extensive measuring in select areas together with an evaluation of the processed data.
48

Vazba GSM modemu na PBX Asterisk / Implementing of GSM modem in PBX Asterisk

Benýšek, Jiří January 2010 (has links)
Short Message Service (shortly SMS) is the most widely used type of communication systems. The main advantages are that allow a fast exchange of messages between devices, a very good availability through GSM and a reasonable price. Nowadays the SMS service support has expanded to include other technologies such as a service of the information navigation and the remote connection. The master‘s thesis concentrates on the Short Message Service, deals with basic principles and statements using by this service. The topic of the thesis is software PBX Asterisk and its possibility of SMS implementation, especially verification of SMS processing goes through the PSTN. After the basic introduction the master‘s work deals with the installation and configuration of the server. The main focus is on an installation of the operating system with an additional pack including necessary libraries and modules for a correct working of the server. The following section is paying attention to the Asterisk server configuration, especially a hardware card installation which is necessary for a connection with analog telephones, done by Bluetooth connections, set up user’s profiles of the SIP protocol and create a dial plan. This is followed by a verification of SMS option of the implementation and communication with GSM modem which is used as a gate for an exchange SMS between PSTN and GSM network. The last chapter of this master‘s thesis comes with the aimed results.
49

Návrh antény PIFA pro GSM pásma / PIFA Antenna design for GSM band

Kollár, Marcel January 2011 (has links)
The main topic of this diploma thesis is a design of the PIFA antenna working in GSM bands. In the beginning there is a brief analysis of planar antennas. The thesis describes PIFA antenna and the techniques for minimization of dimensions of the antenna. Essential part of the thesis is dedicated to multicriterial optimalizaton of the antenna shape. The genetic algorithm programmed in the MATLAB enviroment cooperates with a full-wave solver CST to obrain desired impedance matching of the antenna its radiationt paterns. Also dimensions of the antenna can be minimized using the optimization procedure. Final part of the thesis compares measured data of the optimalized antenna with results obtained in CST Microwave Studio.
50

Design of Class-E Radio Frequency Power Amplifier

Al-Shahrani, Saad Mohammed 18 July 2001 (has links)
Power amplifiers (PA) are typically the most power-consuming building blocks of RF transceivers. Therefore, the design of a high-efficiency radio frequency power amplifier is the most obvious solution to overcoming the battery lifetime limitation in the portable communication systems. A power amplifier's classes (A, AB, B, C, F, E, etc), and design techniques (Load-pull and large-signal S-parameters techniques) are presented. The design accuracy of class-A power amplifier based on the small-signal S-parameters was investigated, where compression in the power gain was used as an indicator for design accuracy. The effect of drain voltage variation on the power gain compression has been studied in this research. The class-E amplifier has a maximum theoretical efficiency of 100%. It consists of a single transistor that is driven as a switch and a passive load network. The passive load network is designed to minimize drain (collector) voltage and current waveforms overlapping, which minimize the output power dissipation. Two L-band class-E amplifiers are implemented in section 5.3. One of them is a lumped elements based circuit and the other is a transmission lines based circuit. Both circuits show good performance (60% PAD) over a wide bandwidth (1.0 GHz). In section 5.4, lumped elements and transmission lines based X-band class-E amplifiers are presented. Both circuits show good performance (62% PAD) over wide bandwidth (4.8 GHz). A new technique to improve the drain efficiency of the class-E amplifier has been proposed. This technique uses two passive networks. One of them is in a series with the shunt capacitor CS and the other is in a series with the transistor's source terminal. This technique shows improvement in the drain efficiency, which jumps from 62% to 82%. Last few years have seen an increase in the popularity of the wireless communication systems. As a result, the demand for compact, low-cost, and low power portable (Single-chip) transceivers has increased dramatically. Among the transceiver's building blocks is the power amplifier. Thus, there is a need for a low-cost power amplifier. A 900 MHz CMOS RF PA with one-watt output power and a high power added efficiency (68%) is presented in chapter 6. This PA can be used in the European standard for mobile communications (GSM) handset transmitter. / Ph. D.

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