Dissertations / Theses: 'Cellular telephone systems'

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Caffery, James Joseph Jr. "Wireless location in CDMA cellular radio systems." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15504.

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Ho, Ming-Ju. "System deployment and capacity enhancing techniques for mobile radio." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/14816.

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Kchao, Camroeum. "Direct sequence spread spectrum cellular radio." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/13719.

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Joung, Jinsoup. "Cochannel interference canceling receivers for TDMA systems." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21806.

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Wang, Li-Chun. "Channel modeling and architecture for cellular-based personal communications." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/13716.

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Geary, Wendy. ""No matter where you go, there you are" but how do we find you? location determination technologies for cellular enhanced 9-1-1 service /." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=982.

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Thesis (M.A.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains vii, 85 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 74-81).

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Ho, Chi-Jui. "Call admission control in cellular networks." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15730.

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Van, Heerden Johan H. "Detecting fraud in cellular telephone networks." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50314.

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Thesis (MSc)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Cellular network operators globally loose between 3% and 5% of their annual revenue to telecommunications fraud. Hence it is of great importance that fraud management systems are implemented to detect, alarm, and shut down fraud within minutes, minimising revenue loss. Modern proprietary fraud management systems employ (i) classification methods, most often artificial neural networks learning from classified call data records to classify new call data records as fraudulent or legitimate, (ii) statistical methods building subscriber behaviour profiles based on the subscriber’s usage in the cellular network and detecting sudden changes in behaviour, and (iii) rules and threshold values defined by fraud analysts, utilising their knowledge of valid fraud cases and the false alarm rate as guidance. The purpose of this thesis is to establish a context for and evaluate the performance of well-known data mining techniques that may be incorporated in the fraud detection process. Firstly, a theoretical background of various well-known data mining techniques is provided and a number of seminal articles on fraud detection, which influenced this thesis, are summarised. The cellular telecommunications industry is introduced, including a brief discussion of the types of fraud experienced by South African cellular network operators. Secondly, the data collection process and the characteristics of the collected data are discussed. Different data mining techniques are applied to the collected data, demonstrating how user behaviour profiles may be built and how fraud may be predicted. An appraisal of the performances and appropriateness of the different data mining techniques is given in the context of the fraud detection process. Finally, an indication of further work is provided in the conclusion to this thesis, in the form of a number of recommendations for possible adaptations of the fraud detection methods, and improvements thereof. A combination of data mining techniques that may be used to build a comprehensive fraud detection model is also suggested.
AFRIKAANSE OPSOMMING: Sellulêre netwerk operateurs verloor wêreldwyd tussen 3% en 5% van hul jaarlikse inkomste as gevolg van telekommunikasie bedrog. Dit is dus van die uiterse belang dat bedrog bestuurstelsels geïmplimenteer word om bedrog op te spoor, alarms te genereer, en bedrog binne minute te staak om verlies aan inkomste tot ’n minimum te beperk. Moderne gepatenteerde bedrog bestuurstelsels maak gebruik van (i) klassifikasie metodes, mees dikwels kunsmatige neurale netwerke wat leer vanaf geklassifiseerde oproep rekords en gebruik word om nuwe oproep rekords as bedrog-draend of nie bedrog-draend te klassifiseer, (ii) statistiese metodes wat gedragsprofiele van ’n intekenaar bou, gebaseer op die intekenaar se gedrag in die sellulêre netwerk, en skielike verandering in gedrag opspoor, en (iii) reëls en drempelwaardes wat deur bedrog analiste daar gestel word, deur gebruik te maak van hulle ondervinding met geldige gevalle van bedrog en die koers waarteen vals alarms gegenereer word. Die doel van hierdie tesis is om ’n konteks te bepaal vir en die werksverrigting te evalueer van bekende data ontginningstegnieke wat in bedrog opsporingstelsels gebruik kan word. Eerstens word ’n teoretiese agtergrond vir ’n aantal bekende data ontginningstegnieke voorsien en ’n aantal gedagteryke artikels wat oor bedrog opsporing handel en wat hierdie tesis beïnvloed het, opgesom. Die sellulêre telekommunikasie industrie word bekend gestel, insluitend ’n kort bespreking oor die tipes bedrog wat deur Suid-Afrikaanse sellulˆere telekommunikasie netwerk operateurs ondervind word. Tweedens word die data versamelingsproses en die eienskappe van die versamelde data bespreek. Verskillende data ontginningstegnieke word vervolgens toegepas op die versamelde data om te demonstreer hoe gedragsprofiele van gebruikers gebou kan word en hoe bedrog voorspel kan word. Die werksverrigting en gepastheid van die verskillende data ontginningstegnieke word bespreek in die konteks van die bedrog opsporingsproses. Laastens word ’n aanduiding van verdere werk in die gevolgtrekking tot hierdie tesis verskaf, en wel in die vorm van ’n aantal aanbevelings oor moontlike aanpassings en verbeterings van die bedrog opsporingsmetodes wat beskou en toegepas is. ’n Omvattende bedrog opsporingsmodel wat gebruik maak van ’n kombinasie van data ontginningstegnieke word ook voorgestel.

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Fitzpatrick, Paul G., and paul g. fitzpatrick@team telstra com. "Traffic modelling and performance of layered cellular networks with overflow." Swinburne University of Technology, 1997. http://adt.lib.swin.edu.au./public/adt-VSWT20060119.093920.

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This thesis reports on an investigation into the teletraffic modelling and performance of layered cellular networks that use overflow for new call and handover attempts in order to improve system performance It addresses the important problems how to model and analyse overflow in large cellular networks so that the overall impact across the network can be evaluated, the overflow policies that can be used with new calls and handovers to improve network performance and how these policies perform under a range of conditions. The general problem of modelling overflow in cellular networks is considered at length and from this it is concluded that the use of overflow in existing schemes such as directed retry, reuse partitioning and overlaid cells can also be described by the simple concepts of intra and inter layer overflow Using these concepts the author formulates the problem of overflow in layered networks as a subset of the general problem of overflow with multiple overflow routes and restricted overflow. This leads to the derivation of the mean and variance of the overflow traffic from a cell with multiple handover routes and restricted handover from the two-dimensional birth death model of the system. These expressions for the mean and variance are used in conjunction with the Equivalent Random Theory and splitting formulae in the development of the Splitting Formula Method or SF Method. The accuracy of three splitting formulae and a simple Poisson approximation are investigated and compared with simulation. From this we conclude that the splitting formulae of Akimaru and Takahashi and Wallstrom provide the best overall result. This method is used to solve the general problem of multiple user classes for an example two layer network. This leads to conclusions on the complex relationship between cell capacity, the proportion of uses that can access the microcells and the proportion of users that can overflow from the microcell to the macrocell. The Modified Splitting Formula Method is an extension of the SF Method that includes handovers and overflow for handovers. A user perceived measure of the effect of new call and handover blocking described by the probability of call failure augments the Modified SF method. This is then used to analyse five new call overflow policies for a three layer network under conditions of extended handover, restrictions on handover for calls in cells at the edge of layers and spatial offset between the peak of the traffic demand and the cell layout. The results give new and valuable insight into the behaviour of layered cellular networks with overflow and the trade-offs in performance that exist when designing and operating these networks.

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Fung, Victor. "Bit error simulation of FSK, BPSK, and pi/4 DQPSK in flat and frequency-selective fading mobile radio channels using two-ray and measurement- based impulse response models." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08142009-040410/.

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Simsim, Mohammed Talal Electrical Engineering &amp Telecommunications Faculty of Engineering UNSW. "Geometry-based stochastic physical channel modeling for cellular environments." Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/26281.

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Telecommunication has experienced significant changes over the past few years and its paradigm has moved from wired to wireless communications. The wireless channel constitutes the basic physical link between the transmitter and the receiver antennas. Therefore, complete knowledge of the wireless channel and radio propagation environment is necessary in order to design efficient wireless communication systems. This PhD thesis is devoted to studying the spatial and temporal statistics of the wireless channel in cellular environments based on a geometry-based stochastic physical channel modeling approach. Contributions in this thesis report include the following: ??? A new physical channel model called the eccentro-scattering model is proposed to study the spatial and temporal statistics of the multipath signals in cellular environments. ??? Generic closed-form formulas for the probability density function (pdf) of angle of arrival (AoA) and time of arrival (ToA) of the multipath signals in each cellular environment are derived. These formulas can be helpful for the design and evaluation of modern communication systems. ??? A new Gaussian scattering model is proposed, which consists of two Gaussian functions for the distribution of scatterers around base station (BS) and mobile station (MS) and confines these scatterers within a scattering disc. ??? The effect of mobile motion on the spatial and temporal statistics of the multipath signals in cellular environments is discussed. Three motion scenarios are considered for the possible trajectory of the mobile unit. Furthermore, two different cases are identified when the terrain and clutter of mobile surrounding have additional effect on the temporal spread of the multipath signals during motion. ??? The physical channel model is employed to assess the performance of a RAKE receiver in cellular environments. ??? Comparisons between uniform scattering and Gaussian scattering, which are the two assumptions for the distribution of scatterers usually used in the derivation of the pdf of AoA, are also presented. ??? An overview of earlier physical channel models and comparisons between these models and with the proposed model are presented.

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Kelly, Ivy Yvonne. "The multipath fingerprint method for wireless E-911 location finding /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.

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Ghaziasgar, Mehrdad. "The use of mobile phones as service-delivery devices in sign language machine translation system." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_7216_1299134611.

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This thesis investigates the use of mobile phones as service-delivery devices in a sign language machine translation system. Four sign language visualization methods were evaluated on mobile phones. Three of the methods were synthetic sign language visualization methods. Three factors were considered: the intelligibility of sign language, as rendered by the method
the power consumption
and the bandwidth usage associated with each method. The average intelligibility rate was 65%, with some methods achieving intelligibility rates of up to 92%. The average le size was 162 KB and, on average, the power consumption increased to 180% of the idle state, across all methods. This research forms part of the Integration of Signed and Verbal Communication: South African Sign Language Recognition and Animation (SASL) project at the University of the Western Cape and serves as an integration platform for the group's research. In order to perform this research a machine translation system that uses mobile phones as service-delivery devices was developed as well as a 3D Avatar for mobile phones. It was concluded that mobile phones are suitable service-delivery platforms for sign language machine translation systems.

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Keung, Yik. "Dynamic threshold call admission control policy of multi-service wireless cellular networks : a statistical approach /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202004%20KEUNG.

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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 80-81). Also available in electronic version. Access restricted to campus users.

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Landron, Orlando. "Microwave multipath resolution in microcellular channels." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03032009-040639/.

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Xu, Zuoying. "Virtually fixed channel assignment in cellular mobile telephone systems: Design, modeling and evaluation." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186331.

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The frequency spectrum allocated to cellular mobile telephone systems is very limited. Efficient channel assignment schemes can significantly increase the utilization of the available frequency channels. Virtually Fixed Channel Assignment (VFCA) is a dynamic channel assignment method. The idea behind it is simple: each cell is allocated a set of nominal channels. A call request generated in a cell is assigned a nominal channel if one is available. Otherwise, a channel from an adjacent cell is borrowed to serve this call as long as frequency interference constraints are satisfied. VFCA is a promising method because (i) it is efficient in channel assignment, and (ii) it is relatively easy to implement compared to other dynamic channel assignment methods. VFCA has been analyzed based primarily on simulation studies in the past twenty years. In this thesis, we focus our study on development of new channel borrowing strategies and analytical models for VFCA. The contribution of this work is summarized as follows. (1) Development of an queuing model for performance analysis of VFCA. This model may also be used to conduct sensitivity analysis on some system parameters when VFCA is used. (2) Proposed a new channel reservation scheme for handoffs. (In a cellular system, when a call using a channel crosses a cell boundary, it needs to be handed off to a new channel in the new cell. This is called a handoff.) An optimization model for this channel reservation scheme is developed. (3) Applied the fluid-flow approach to modeling an integrated mobile cellular system that uses VFCA to estimate the distribution of data queue length in a cell of the system. These results are useful in the design, performance analysis and optimization of VFCA schemes.

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Patel, Chirag S. "Channel modeling and estimation for mobile-to-mobile OFDM communications." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/13552.

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Sung, Che-ming. "A network approach to the study of the next generation in the mobile telephone market /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1470898X.

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Kelly, Sherry L. "Cellular towers and community land-use issues a case study of Harpers Ferry and Jefferson County, West Virginia /." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1392.

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Thesis (M.A.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains v, 45 p. : ill. (some col.), maps. Vita. Includes abstract. Includes bibliographical references (p. 41-42).

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Ecker, Katelyn D. "Mobile phones as a social medium for the deaf : a uses and gratifications study /." Online version of thesis, 2008. http://hdl.handle.net/1850/7098.

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So, Hong-pak Ryan. "A study on the segmentation of Hong Kong mobile communications market and its marketing implications /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14038614.

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Jiang, Hai. "Coverage vs. capacity analysis for CDMA cellular networks /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3074412.

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Li, Yingjie. "Bit error rate simulation of a CDMA system for personal communications." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07282008-135717/.

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Tran, Thuy Thomas. "Propagation prediction for PCS design in urban microwave channels." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03042009-040358/.

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Glowacki, Jason P. "Impact of the Telecommunications Act of 1996 and spectrum allocation on cellular telephone technology." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FGlowacki.pdf.

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Du, Toit Riaan. "The applications of superconductors in cellular network base stations." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/20433.

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Thesis (MScIng)--University of Stellenbosch, 2008.
ENGLISH ABSTRACT: The Applications of Superconductors in Cellular Network Base Stations R. Du Toit Department of Electronic Engineering University of Stellenbosch Private Bag X1, 7602 Matieland, South Africa Thesis: MScEng (E&E) March 2008 Wireless communications have increasingly become part of our world. The growth of radio frequency (RF) wireless communications has led to an increasing demand for frequency spectrum licenses, increased system capacity and larger user bandwidths. These demands lead to frequent improvements on the physical and higher layers of wireless communication protocols. Changes in the physical layer are frequently followed by the need for replacement of dedicated hardware components. The need therefore exists for a more general and programmable physical layer. A more general and programmable radio architecture implies increased radio front-end performance without losing programmability. The contribution of this thesis is the analysis of how superconductor electronics (SCE) using Rapid Single Flux Quantum (RSFQ) logic may advance wireless radio front-ends by providing a general-purpose programmable radio architecture. Superconductor analogue to digital converters (ADCs) are employed as high performance, programmable digitization structures. Once a received signal is digitized, SCE can be used to rapidly do recursive operations such as synchronization and multi-path delay estimation. These operations are based on correlation, and for evaluation of such operations with SCE the popular CDMA multiplexing method is studied along with the WCDMA protocol used in the 3G UMTS standard. Two delta-type oversampling superconductor ADC modulator designs are presented and evaluated along with a hybrid decimation filter design, using both the benefits of SCE and room temperature electronics. A fast RSFQ correlator design is also presented and evaluated for use in a multi-path estimation structure. A rapid multi-path delay estimation architecture based on fast RSFQ circular data buffers and correlators is presented. The architecture uses the fast speeds of RSFQ logic to obtain accurate path delay estimates in a rapidly changing wireless environment. It is concluded that RSFQ-based wireless receiver components offer promising new options for data conversion, correlation and multi-path delay estimation implementations.
AFRIKAANSE OPSOMMING: The Applications of Superconductors in Cellular Network Base Stations R. Du Toit Department of Electronic Engineering University of Stellenbosch Private Bag X1, 7602 Matieland, South Africa Thesis: MScEng (E&E) March 2008 Draadlose kommunikasie word al hoe meer deel van ons wêreld. Groei in radiofrekwensietipe kommunikasie het gelei tot ’n toenemende aanvraag na frekwensiespektrum lisensies, vergrote stelselkapasiteit en groter gebruikerbandwydtes. Hierdie aanvrae lei tot gereelde en spoedige verbeteringe op die fisiese en hoër lae van huidige draadlose kommunikasieprotokol. Veranderinge in die fisiese laag vereis gewoonlik dat toegewyde hardewarde komponente vervang word. Die behoefte bestaan dus vir ’n meer algemene, programmeerbare fisiese laag. Dit vereis dus ’n verbetering in die radio-ontvanger se komponente naaste aan die antenna sonder om programmeerbaarheid te verloor. Die bydrae van hierdie tesis is hoofsaaklik die analise van hoe supergeleierelektronika wat van Rapid Single Flux Quantum (RSFQ) logika gebruik maak, huidige draadlose sellulêre basisstasies se fisiese laag kan verbeter deur ’n meer algemene en programmeerbare radio-argitektuur op te lewer. Supergeleier analoog-na-syfer omsetters (ADCs) word bestudeer as moontlike programmeerbare versyferingstrukture wat steeds hoë werkverrigting lewer. Wanneer ’n ontvangde sein in digitale vorm omgesit is, kan supergeleierelektronika gebruik word om vinnig rekursiewe operasies uit te voer. Voorbeelde van sulke operasies is sinkronisasie en die waardebepaling van die vertraging van verskillende paaie wat ’n sein volg na die ontvanger. Hierdie spesifieke operasies se werking is gebaseer op korrelasie, en vir die evaluasie van sulke operasies met supergeleierelektronika is die gewilde wyeband-CDMA (WCDMA) protokol wat gebruik word in die 3G UMTS-standaard. Twee supergeleier-delta-tipe oorversyferings-ADC-moduleerderontwerpe word voorgelê en evaluasie word daarop gedoen saam met ’n hibriede desimasiefilterontwerp wat gebruik maak van beide die voordele van supergeleierelektronika en kamertemperatuurelektronika. ’n Vinnige RSFQ-korreleerder word ook voorgelê en evaluasie word daarop gedoen vir gebruik binne ’n multi-padvertraging-waardebepalerstruktuur. Hierdie struktuur wat gebaseer is op RSFQ sirkulêre buffers en korreleerders, word voorgelê. Die waardebepaler maak gebruik van die spoed van RSFQ-logika om akkurate multi-padvertragingswaardes te bepaal in ’n vinnig veranderende draadlose omgewing. Die gevolgtrekking word gemaak dat RSFQ-gebaseerde draadlose ontvangerkomponente groot voordele in versyfering-, korreleerder- en multi-padvertragingsbepaler-toepassings bied.

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Pendyala, Chandra Mohan. "On the optimal location of transmitters for micro-cellular radio communication system design." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07112009-040406/.

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Darweesh, Turki H. "Capacity and performance analysis of a multi-user, mixed traffic GSM network." Ottawa, 1999.

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Brooks, Stephen A. "Analysis of large area synchronous codedivision multiple access (LAS-CDMA)." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FBrooks.pdf.

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Thavarajah, Arunasala Iyer. "A study of fixed channel assignment algorithms for cellular mobile radio systems." Thesis, Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21241144.

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Lichtenstein, Joseph. "Low computational complexity bit error rate simulation for personal communications systems in multipath and fading environments." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06102009-063138/.

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Kong, Tsz-wai Sally. "Business development of PCN operators in Hong Kong /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19943271.

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Wong, Wing-lun Alan. "The development and competition of the mobile phone industry in Hong Kong /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19872124.

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Zhu, Jian. "Indoor/Outdoor Location of Cellular Handsets Based on Received Signal Strength." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11489.

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Indoor/Outdoor Location of Cellular Handsets Based on Received Signal Strength Jian Zhu 123 pages Directed by Dr. Gregory D. Durgin Accurate geo-location is an important emerging technology for public safety, commercial use, and military application. Especially, in the United States, the wireless Enhanced 911 (E911) rules by the Federal Communication Commission (FCC) seek to provide 911 dispatchers with additional information on wireless 911 calls. This dissertation presents a novel technique for indoor/outdoor location of cellular handsets based on received signal strength (RSS) measurements taken by a cellular handset of the surrounding base stations. RSS location accuracy for different environments is studied as a function of base station separation distance, cell sector density, measurement density, radio propagation environment, and accuracy of measurement. The analytical and experimental results in this thesis serve as a guideline for the accuracy of RSS signature location technology under different conditions. Accurate outdoor to indoor penetration models are proposed and validated for dense urban areas by introducing pseudo-transmitters to simulate the wave-guiding effects in urban canyon environments. A set of location algorithms is developed to improve location accuracy. Furthermore, an algorithm to discriminate between indoor and outdoor users is proposed and validated. The research results demonstrate the feasibility of RSS location techniques to meet the FCCs requirements for E911 accuracy in urban and semi-urban environments. The techniques remain accurate for indoor handsets. The results also suggest that a hybridization of the handset-based GPS method and the RSS signature method may prove to be the most effective solution for locating handsets across a range of environments; including rural, suburban, dense urban, and indoor.

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Thoma, Berthold. "Bit error rate simulation enhancement and outage prediction in mobile communication systems." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09052009-040547/.

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Parameswaran, Subramanian T. "Software for site specific propagation prediction." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063433/.

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Abidogun, Olusola Adeniyi. "Data mining, fraud detection and mobile telecommunications: call pattern analysis with unsupervised neural networks." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&amp.

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Huge amounts of data are being collected as a result of the increased use of mobile telecommunications. Insight into information and knowledge derived from these databases can give operators a competitive edge in terms of customer care and retention,
marketing and fraud detection. One of the strategies for fraud detection checks for signs of questionable changes in user behavior. Although the intentions of the mobile phone users cannot be observed, their intentions are reflected in the call data which define usage patterns. Over a period of time, an individual phone generates a large pattern of use. While call data are recorded for subscribers for billing purposes, we are making no prior assumptions about the data indicative of fraudulent call patterns, i.e. the calls made for billing purpose are unlabeled. Further analysis is thus, required to be able to isolate fraudulent usage. An unsupervised learning algorithm can analyse and cluster call patterns for each subscriber in order to facilitate the fraud detection process.

This research investigates the unsupervised learning potentials of two neural networks for the profiling of calls made by users over a period of time in a mobile telecommunication network. Our study provides a comparative analysis and application of Self-Organizing Maps (SOM) and Long Short-Term Memory (LSTM) recurrent neural networks algorithms to user call data records in order to conduct a descriptive data mining on users call patterns.

Our investigation shows the learning ability of both techniques to discriminate user call patterns
the LSTM recurrent neural network algorithm providing a better discrimination than the SOM algorithm in terms of long time series modelling. LSTM discriminates different types of temporal sequences and groups them according to a variety of features. The ordered features can later be interpreted and labeled according to specific requirements of the mobile service provider. Thus, suspicious call behaviours are isolated within the mobile telecommunication network and can be used to to identify fraudulent call patterns. We give results using masked call data
from a real mobile telecommunication network.

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Todd, Stephen Ross Carleton University Dissertation Engineering Electrical. "Empirical evaluation of diversity techniques for indoor digital radio at 1.75 GHz." Ottawa, 1992.

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Ng, Kok Keng. "Smart antenna application in DS-CDMA mobile communication system." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FNg.pdf.

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Cooper, David Lee. "An analysis of cellular telephone and INMARSAT systems for providing radio data link computer communications for US Navy vessels /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA278143.

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Thesis (M.S. in Management)--Naval Postgraduate School, December 1993.
Thesis advisor(s): Dan C. Boger ; Alan W. McMasters. "December 1993." Includes bibliographical references. Also available online.

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Cooper, David Lee Jr. "An analysis of cellular telephone and INMARSAT systems for providing radio data link computer communications for US Navy vessels." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/39672.

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Approved for public release; distribution is unlimited.
This thesis examines radio frequency data link computer communications systems with emphasis on their potential application to ship/ shore communications. Covered are two systems that experts believe hold the most promise for DoD application, International Maritime Satellite (INMARSAT) and cellular radiotelephones. An analysis of system capabilities, cost, and future potential is performed for each, and then the two systems are compared. In addition, a thorough discussion of the security issues for each system and final conclusions/recommendations are presented. The conclusions suggest that increased cellular radiotelephone usage vice INMARSAT by fleet units would optimize fleet readiness and improve supply system performance. Based on these conclusions, this author's recommendation is that all Navy ships be equipped with a cellular telephone system, while all aircraft carriers and amphibious aircraft carriers be equipped with both cellular and INMARSAT systems.

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Sung, Che-ming, and 宋志明. "A network approach to the study of the next generation in the mobile telephone market." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31266824.

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Cosgrove, Stephen Richard. "Mobile data services adoption in New Zealand future predictions : a thesis submitted to the graduate faculty of Design and Creative Technologies, Auckland University of Technology, School of Computer and Information Sciences in partial fulfilment of the requirements for the degree of Master of Computing Information Systems, Auckland, New Zealand, 2007." Click here to access this resource online, 2007. http://hdl.handle.net/10292/402.

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Thesis (MCIS - Computer and Information Sciences) -- AUT University, 2007.
Includes bibliographical references. Also held in print (xii, 100 leaves : ill. ; 30 cm.) in the Archive at the City Campus (T 384.5 COS)

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Bittle, Charles C. "Linearity and monotonicity of a 10-bit, 125 MHz, segmented current steering digital to analog converter." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2541/.

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The purpose of this research is to determine the linearity and monotonicity of the THS5651IDW digital to analog converter (DAC), a prototype of the future Texas Instruments TLV5651, 10-bit, 125 MHz communication DAC. Testing was conducted at the Texas Instruments facility on Forest Lane, Dallas, Texas. Texas Instruments provided test equipment, software and laboratory space to obtain test data. Analysis of the data found the DAC to be monotonic since the magnitude of the differential nonlinearity (DNL) was less than ± 1 least significant bit (LSB) and the integral nonlinearity (INL) was less than ± 0.5 LSB. The study also showed that the DAC has primarily negative DNL although the DNL is well within the desired specification.

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Nespolo, Daniele. "Relação entre valor percebido, reputação, confiança e custos de troca como determinantes da retenção de clientes no contexto de serviços de telefonia móvel." reponame:Repositório Institucional da UCS, 2014. https://repositorio.ucs.br/handle/11338/923.

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Manter e ampliar relacionamentos com clientes, na área de serviços, é estimular a retenção de clientes e, consequentemente, fazer com que as empresas passem a ser vistas de forma diferenciada pelo mercado. Entretanto, as empresas prestadoras de serviços devem compreender o processo que envolve os clientes nos encontros de serviços, investigando os construtos que implicam na captação e na retenção dos mesmos, para que sejam desenvolvidas estratégias adequadas. Sendo assim, esta pesquisa propôs a replicação e testagem de um Modelo Teórico, considerando os construtos Valor Percebido, Reputação do Provedor de Serviços, Confiança e Custos de Troca como determinantes da Retenção de Clientes. Desenvolveu-se, então, a construção teórica acerca da Retenção de Clientes e dos demais construtos contemplados nesta pesquisa, com a intenção de compreender e analisar a atuação dos mesmos no relacionamento entre clientes e prestadores de serviços, bem como suas relações com as estratégias competitivas das empresas. Dando sequência ao estudo, foi realizada a pesquisa quantitativa, por meio da aplicação de uma survey. Para a análise dos dados, foram utilizadas estatísticas multivariadas, incluindo a Modelagem de Equações Estruturais, para que fossem testadas e analisadas as hipóteses levantadas pelo estudo aqui proposto. Os resultados evidenciaram que: o valor percebido pelos clientes influencia positivamente a reputação do provedor de serviços; o valor percebido pelos clientes não influencia positivamente os custos de troca; a reputação do provedor de serviços influencia positivamente a confiança do cliente no provedor de serviços; a reputação do provedor de serviços não influencia positivamente os custos de troca; a confiança depositada pelo cliente em relação ao provedor de serviços influencia positivamente a retenção de clientes; os custos de troca não influenciam positivamente a retenção de clientes; e a reputação do provedor de serviços influencia positivamente a retenção de clientes.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES.
Maintaining and expanding relationships with customers in the service area, is to encourage customer retention and thus cause the corporation to be viewed differently by the market. However, the service providers must understand the process involving customers in service encounters, investigating the constructs involving the capture and retention of the same, so that appropriate strategies can be developed. Thus, this research has proposed replication and testing a theoretical model, considering the constructs Perceived Value, Reputation of Service Provider, Reliability and Cost of Exchange as determinants of Customer Retention. Developed the theoretical construction about Customer Retention and others constructs included in this study, with the intent to understand and analyze the performance of the same in the relationship between clients and service providers, as well as its relations with the competitive strategies of firms. Giving sequence to the study, was realized a quantitative research by the application of a survey. For data analysis, multivariate statistics, including Structural Equation Modeling, to be tested and analyzed the hypotheses proposed by the study presented here. The results showed that: perceived value positively influences the reputation of the service provider; perceived value by customers not positively influences switching costs; the reputation of the service provider positively influences customer trust in the provider; the reputation of the service provider not positively influences the switching costs; the trust placed by the customer in relation to the provider positively influences customer retention; the switching costs not positively influences customer retention; and the reputation of the service provider positively influences customer retention.

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So, Hong-pak Ryan, and 蘇康伯. "A study on the segmentation of Hong Kong mobile communications market and its marketing implications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31266812.

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Nguyen, Son. "Capacity and Throughput Optimization in Multi-cell 3G WCDMA Networks." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4948/.

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User modeling enables in the computation of the traffic density in a cellular network, which can be used to optimize the placement of base stations and radio network controllers as well as to analyze the performance of resource management algorithms towards meeting the final goal: the calculation and maximization of network capacity and throughput for different data rate services. An analytical model is presented for approximating the user distributions in multi-cell third generation wideband code division multiple access (WCDMA) networks using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This model allows for the calculation of the inter-cell interference and the reverse-link capacity of the network. An analytical model for optimizing capacity in multi-cell WCDMA networks is presented. Capacity is optimized for different spreading factors and for perfect and imperfect power control. Numerical results show that the SIR threshold for the received signals is decreased by 0.5 to 1.5 dB due to the imperfect power control. The results also show that the determined parameters of the 2-dimensional Gaussian model match well with traditional methods for modeling user distribution. A call admission control algorithm is designed that maximizes the throughput in multi-cell WCDMA networks. Numerical results are presented for different spreading factors and for several mobility scenarios. Our methods of optimizing capacity and throughput are computationally efficient, accurate, and can be implemented in large WCDMA networks.

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Chavannes, Nicolas Pierre. "Local mesh refinement algorithms for enhanced modeling capabilities in the FDTD method /." Konstanz : Hartung-Gorre, 2002. http://www.loc.gov/catdir/toc/fy0801/2006483066.html.

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Croft, Neil John. "Secure interoperation of wireless technologies." Diss., Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-12072004-082613.

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Stegmann, Johann. "Design and implementation of a digital video recorder, with live video streaming to cellphone over mobile broadband." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2642.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007.
The work presented in this Thesis relates to the increased capabilities of the mobile Internet and the possible use of cellphones as an enhancement to video surveillance systems. The focus of the Thesis is on the delivery of live video content to Java enabled cellphones. The various characteristics, capabilities and limitations of the mobile networks- and phones are investigated. Various options for streaming video content to cellphones are also explored. The design and implementation of a digital surveillance system with the ability to stream live video to a cellphone is presented. Two versions of the streaming protocol are developed and implemented in cellphone applications, with which the video stream can be viewed. An evaluation and real-life testing of the applications are presented. Recommendations regarding further enhancements are provided.

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Dissertations / Theses on the topic 'Cellular telephone systems'

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