Dissertations / Theses on the topic 'EGPSR'

<p>The most widely used protocol for providing reliable service and congestion control in the Internet is the Transmission Control Protocol (TCP). When the Internet is moving towards more use in mobile applications it is getting more important to know how TCP works for this purpose.</p><p>One of the technologies used for mobile Internet is the Enhanced General Packet Radio Service (EGPRS) extension to the popular GSM system. This thesis presents a low-level analysis of TCP performance in an EGPRS system and an overview of existing TCP, GSM and EGPRS technologies.</p><p>The bottleneck in an EGPRS system is the wireless link – the connection between the mobile phone and the GSM base station. The data transfer over the wireless link is mainly managed by the complex RLC/MAC protocol.</p><p>In this thesis, simulations were made to identify some problems with running TCP and RLC/MAC together. The simulations were made using existing EGPRS testing software together with a new TCP module. The simulation software is also briefly described in the thesis.</p><p>Additionaly, some suggestions are given in order to enhance performance, both by changing the EGPRS system and by modifying the TCP algorithms and parameters.</p>

<p>This master thesis has been done at Enea Epact AB. The purpose of this thesis is to develop and implement a Link Quality Control algorithm for GPRS/EPGRS in the current testing tool. A Link Quality Control (LQC) shall take quality values from mobile stations and base stations and decide a codingsscheme that opimizes the throughput of data. </p><p>The Advantage with LQC is that it adapts the used coding scheme to the channel quality. If the channel quality is too bad for the used coding scheme, a slower coding scheme with more redundancy should be selected. On the other hand, if the channel quality is too good for the used coding scheme, LQC should recommend a faster coding scheme with less redundancy. </p><p>The testing tool is now using a static coding schme that doesn’t change during a data session. An LQC is therefore necessary for better simulation of the traffic and to make the tests more real.</p>

Enhanced Data Rates for Global Evolution (EDGE) is one of the 3G wireless communication standards, which provides higher data rates by adopting 8-PSK modulation in TDMA system infrastructure of GSM. In this thesis, a turbo detection receiver for Enhanced General Packet Radio Services (EGPRS) system, which is the packet switching mode of EDGE, is studied. In turbo detection, equalization and channel decoding are performed iteratively. Due to 8-ary alphabet of EGPRS modulation, full state trellis based equalization, as usually performed in GSM, is too complex not only for turbo detection but even for conventional equalization<br>so suboptimum schemes have to be considered. The Delayed Decision Feedback Sequence Estimation (DDFSE) is chosen as suboptimal and less complex trellis based scheme and it is examined as a conventional equalization technique firstly. It is shown that the DDFSE has a fine tradeoff between performance and complexity and can be a promising candidate for EGPRS. Then it is employed to reduce the number of the trellis state in turbo detection. Max-log-MAP algorithm is used for soft output calculations of both SISO equalizer and SISO decoder. Simulation results illustrate that proposed turbo detection structure improves bit error rate and block error rate performance of the receiver with respect to the conventional equalization and decoding scheme. The iteration gain varies depending on modulation type and coding rate of Modulation Coding Scheme (MCS) employed in EGPRS.

Due to the rapid growth of wireless multimedia service, new features such as improved spectral efficiency, latency and increased peak throughput are standardized in the current GSM/EDGE system. Higher order modulations and symbol rates are defined in Enhanced General Packet Radio Service phase 2 (EGPRS2) to achieve better throughput. However, the computational complexity in the traditional receiver can be very high when increased modulation orders are applied; additionally, the system becomes more sensitive to the impairments at an increased symbol rate. It is therefore desirable to have a less complex and more robust demodulator. Recently, a new study item which introduces the multi-carrier technique was proposed in the 3rd Generation Partnership Project (3GPP) standardization. Based on the channel partitioning using the Discrete Fourier Transform (DFT), a simple equalizer can be used, which greatly reduces the computational complexity on receiver, meanwhile achieves good throughput and robustness against impairments. In this thesis, another channel partitioning method by means of the Discrete Cosine Transform (DCT) is studied. Transmitter and receiver algorithms are developed, including a pre-filter designed at the receiver to facilitate the channel diagonalization. The link level performance is evaluated by means of simulations, under different test scenarios. The system’s robustness against impairments and peak-to-average ratio (PAR) reduction are also evaluated, and compared with a system based on the DFT pre-coding. From the simulations, the conclusions can be drawn that in this implementation, the DFT precoded EGPRS2 outperforms the DCT pre-coded EGPRS2 in all scenarios. The DCT pre-coded system also shows worse robustness against impairments and higher peak-to-average ratio reduction loss in throughput. The impact of pre-filter design on the DCT pre-coded system has also been analyzed, and it shows that there is a tradeoff between achieving good symmetrization, and preserving channel information in the frequency domain.

<p>This thesis deals with output power calibration of a mobile platform that supports EGPRS.Two different topics are examined. First some different measurement methods are compared concerning cost efficiency, accuracy, and speed and later measurements are carried out on a mobile platform. </p><p>The output power from the mobile platform is controlled by three parameters and the influence on the output power when varying those parameters is investigated and presented. Furthermore, two methods of improving the speed of the calibration are presented. </p><p>The first one aims to decrease the number of bursts to average over as much as possible. The conclusion is that 10-20 bursts are enough for GMSK modulation and about five bursts for 8PSK modulation. The purpose of the second investigation is to examine the possibility to measure the output power in one modulation and frequency band, and then calculate the output power in the other bands. The conclusion in this case is that, based on the units investigated, it is possible for some values of the parameters and in some frequency bands. However, more units need to be included in the basic data for decision-making and it is possible that the hardware variation is too large.</p>

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>Atualmente, há uma demanda crescente por serviços que exploram a integração entre as tradicionais redes de pacotes (como a Internet) e as redes celulares de última geração. Além das aplicações que visam ao transporte de dados em si, há linhas de pesquisa no sentido de oferecer serviços de voz sobre IP em redes celulares, ou seja, explorando o paradigma da transmissão de voz em pacotes. Uma destas aplicações é o Push to Talk over Cellular, ou PoC, serviço no qual, durante uma sessão, apenas um usuário por vez pode falar em modo half duplex. No PoC, assim como em toda aplicação baseada em voz sobre IP, o atraso fim-a-fim, a variação do atraso (jitter) e as taxas de perdas (além de outros fatores) influenciam a qualidade da recepção da voz nos extremos finais da comunicação. Os resultados aqui apresentados estão focados no requisito de atraso fim-a-fim dos pacotes de voz, cujos valores variam dependendo do tamanho destes pacotes, do número de usuários por canal e, principalmente, das condições do meio (razão C/I). Também são apresentados resultados referentes às simulações que validaram o modelo da rede EGPRS, mais especificamente, referentes às características da interface aérea baseada no EDGE. Durante as simulações, considerou-se que os canais eram dedicados às sessões PoC, isto é, sem nenhuma espécie de tráfego concorrente.<br>Nowadays, there is a increasing demand for services that join traditional packet data networks (like Internet) and last generation cellular systems. Besides applications based on data only, there are researches about offer services of voice calls in cellular networks based on packet switched transmission mode. One of that is Push to Talk over Cellular, or PoC, that is a real-time service based on delivery of voice traffic in packets between two or more parties in a half duplex way. Like traditional VoIP services, the end-to-end delay, the jitter and the lost rates can affect the transmission and reception of the voice between the extremes of the communication. The results are focused on end-to-end delay of the voice packets in a PoC session, whose values can change drasticly depending on the size of the packets, the number of users sharing a channel and, mainly, the conditions of the medium (C/I rates). The model used for the EGPRS network, in special, the EDGE air interface, is studied by simulations and the results are presented and analysed too. This work presents a mean of estimating the capacity of EGPRS/EDGE channels of supporting PoC sessions without considering any other type of traffic.

Cette thèse étudie différentes problématiques qui visent à améliorer la qualité de service offerte aux utilisateurs et à mettre en oeuvre des mécanismes de handover performants dans les réseaux E-GPRS. La première partie étudie différents mécanismes d'allocation dynamique de ressources sur l'interface Abis. Ces mécanismes doivent permettre le déploiement de la technologie E-GPRS tout en préservant la structure de l'interface Abis existante. La seconde partie analyse différentes approches de handover pouvant être mises en oeuvre pour assurer la mobilité des utilisateurs dans les réseaux E-GPRS. Nous formulons plusieurs propositions pour améliorer les performances du basculement et mettre en place un véritable handover. Nous présentons les évolutions récentes de la normalisation, puis exposons nos résultats qui permettent de comparer les performances des différents mécanismes. La troisième partie s'intéresse aux handover inter-systèmes. Nous analysons le passage d'une station de base E-GPRS à un point d'accès WIFI intégré au réseau d'accès mobile. Nous analysons également les mécanismes à mettre en place pour le transfert de données en mode Streaming. Nos résultats montrent les bénéfices apportés par l'introduction d'une couche de convergence au niveau liaison de données. La quatrième partie étudie les mécanismes de compression qui peuvent être mis en oeuvre pour réduire la taille des messages de signalisation SIP. Cette étude vise à réduire le temps de transmission de la signalisation – à travers des bearer bas débit – et à économiser l'utilisation des ressources radio<br>This thesis studies several problems to improve the quality of service offered to subscribers and to set up handover mechanisms. The first part deals with dynamic resources allocation mechanisms for the Abis interface. These mechanisms must allow the deployment of the E-GPRS technology, while preserving the existing Abis structure. The second part analyzes various handover approaches which can be set up to allow user mobility in the E-GPRS networks. We introduce several proposals to improve reselection performances and to set up a real handover. We details recent evolutions of the standardization, then we expose our results which allow to compare performances of the various studied mechanisms. The third part deals with inter-systems handovers. We analyze the terminal transfer from an E-GPRS base station to a WIFI access point integrated to the mobile access network. We also study the performances of several handover mechanisms which can be used in case of streaming traffic. Our results show the benefits offered by the introduction of a convergence layer at LLC level. The fourth part studies compression mechanisms which can be set up to reduce the size of SIP signalization messages. The aim of this study is to reduce the signalization transmission delays - through low data rate bearers - and to reduce the use of radio resources

Made available in DSpace on 2014-06-12T15:59:19Z (GMT). No. of bitstreams: 2 arquivo5031_1.pdf: 3343228 bytes, checksum: 5473b22f6502ccef2e12e259b590641d (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2002<br>Atualmente o mercado das comunicações móveis está sendo dirigido pela necessidade dos serviços de dados. Entre os sistemas da primeira e segunda geração (1G e 2G), o GSM (Global System Mobile) é indiscutivelmente o mais utilizado no mundo para aplicações de voz, porém, continua oferecendo serviços de dados com baixas taxas de transmissão, as quais em paralelo com as baixas capacidades dos sistemas, são os principais problemas do progresso da multimídia móvel. Além disso, os serviços de dados são caracterizados pela necessidade de grandes larguras de banda. Sendo assim, o GSM que originalmente foi desenvolvido para transmissão de voz e serviços de dados com baixas taxas, está rapidamente sendo atualizado para incorporar novos serviços multimídia. Na sua geração intermediária 2,5G, com o HSCSD (High Speed Circuit Switching Service Data) e o GPRS (General Packet Radio Service), possuirão suas taxas de dados aumentadas em três vezes com a introdução de suas versões melhoradas, ECSD (Enhanced Circuit Switched Data) e EGPRS (Enhanced GPRS), juntos esses dois sistemas são denominados de EDGE (Enhanced Data Rate for Global Evolution). O EDGE utilizará uma modulação de alto nível denominada 8PSK (8 Phase Shift Keying) em conjunto com a GMSK (Gaussian Minimum Shift Keying), utilizada pelo GPRS, também usará esquemas de codificação mais eficientes e mecanismos de controle de qualidade do link, IR (Incremental Redundancy) e LA (Link Adaptation), os quais trazem benefícios quando utilizados em boas condições de propagação. Este trabalho trata da evolução dos serviços de dados, em especial da 2,5G, concentrando-se no estudo do EDGE, mais especificamente do EGPRS, com a abordagem dos seus principais aspectos e características. Foram realizados estudos considerando as alocações single e multislot, suas especificações, para a transmissão de diferentes modelos de dados, Funet, Railway e Mobitex, entre PCU (Packet Control Unit) e MSs (Mobile Stations). Desenvolveu-se um protótipo com o objetivo de simular esse nível de abstração e testar um algoritmo para a otimização das alocações, de forma a permitir o melhor estudo e a análise do desempenho do sistema

This report describes a thesis work carried out at ABB Robotics in Västerås. The objective of this thesis is to find technologies  and equipments  for wireless data transfer  suitable for the present and future needs of ABB Robotics Remote Service for large installations in industrial environments. ABB Robotics has a Remote Service solution to securely gather information from robots, manage alarms and potentially execute remote commands by ABB Robotics. This solution consists of an intelligent Service  Box plugged to the robot. This  Service Box is also connected through GPRS or directly through Internet to create a secure VPN connection to a central Remote Service  server. The Remote Service Box is well  suited  for small customers with  1-10 robots with plug  and play installation, but show limitations at a larger scale of deployment  due to equipment costs,  network and installation complexity. A new Service Box is planned that will accommodate future added functionality to Remote Service. This Service Box will require new network solutions as the added functionality  is depending on a higher bandwidth than the GPRS networks can deliver. I have surveyed most existing  wireless  networking technologies  and  analyzed  them  withrespect  to function, cost and availability which provide a knowledge base that makes it possible to find  suitable  solutions. When the most suitable technologies are identified a survey was performed to find equipments that meet the requirements at the lowest cost. A new hierarchical network topology is proposed  that will lead to cost savings by replacing multiple WAN connections in the present solution with  a network switch and  single WAN connection to Internet. As manufacturers of network equipments for industrial environments are relatively few, alternative solutions were also investigated in order to find the most cost effective solutions. The  proposed  network topology together with the data from the surveys lead to recommendations on using Wi-Fi  in the wireless LAN and  a  3G mobile  network for the WAN connection to Internet, as well as recommendations on alternative network equipments that  potentially  can  lead to substantial savings when the new network solutions are implemented.

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-23T12:16:16Z No. of bitstreams: 0<br>Made available in DSpace on 2017-11-23T12:16:16Z (GMT). No. of bitstreams: 0<br>O desenvolvimento industrial e urbano tem causado aumento mundial das emissões de poluentes atmosféricos. Nas áreas metropolitanas o problema da deterioração da qualidade do ar tem se constituído numa das mais graves ameaças à qualidade de vida dos seus habitantes e os veículos automotores contribuem diretamente com o aumento do material particulado (MP). Neste trabalho foram descritas as etapas metodológicas para validar a Tibouchina granulosa como biomonitor ambiental. Assim, foram abordados a caracterização das folhas, categorização do MP, protocolo de remoção de MP e determinação dos EGPs (Pd, Pt e Rh) na deposição seca das folhas. Para tanto foram realizadas quatro coletas anuais (2011-2014) de folhas, entre os meses de agosto e setembro, em pontos específicos. Os resultados da caracterização mostraram que as folhas permanecem residentes nos ramos por até 6 meses e ocorre o desenvolvimento duas novas folhas por nó a cada mês, indicando que o biomonitoramento pode ser realizado com distribuição temporal e espacial. Os caracteres anatômicos foliares mais relevantes são os tricomas, sendo caracterizados quatro tipos (glandular, adpresso-escabro, base ramificada e estrigoso) que adsorvem o MP. No protocolo de remoção da deposição seca, o número de MP variou de acordo com os diferentes reagentes analíticos utilizados, sendo os mais significativos o ALCONOX&reg e a água régia, que apresentaram valores de remoção na faixa de 99-98% e de 94-99%. As estimativas das incertezas analíticas dos EGPs apresentam valores de uCPt=5% (Pt), uCPd=12% (Pd) e uCRh=5% (Rh) e as incertezas de amostragem, os valores de 57% para o Pd, 24% para a Pt e 27% para o Rh. Portanto, a incerteza expandida foi da Pt U=48%, Pd U=86% e Rh U=9%, a incerteza do Rh apresentou valor mais baixo por ser o elemento minoritário. A elevada sensibilidade do método para determinação dos EGPs apresentou limite de detecção de 0,1 pg g-1 para o Pd, 1,3 pg g-1 para Pt e 0,3 pg g-1 para o Rh e acompanhada boa reprodutibilidade. As concentrações dos EGPs encontradas na deposição seca nos vários pontos de coletas indicaram a clara diferença de acúmulo destes elementos entre o ponto de referência e os locais impactados, sugerindo que a liberação dos EGPS pelos catalisadores veiculares pode ser considerada alta. A evidência da presença dos EGPs na deposição seca foi confirmada por meio da análise da distribuição, que mostrou claramente a similaridade com o material de referência certificado Used Auto Catalystc-2557. As distribuições espaciais dos EGPs foram semelhantes para a Coleta 2, indicando os hot points da RMSP. As concentrações do EGPs foram ordenadas em Pt>Pd>Rh e foram mais baixas no ponto de coleta para controle das amostragens em comparação com os outros locais amostrados. Pode ser concluído que as folhas de T. granulosa foram validadas como biomonitor passivo dos EGPs constituintes de catalisadores veiculares.<br>Tese (Doutorado em Tecnologia Nuclear)<br>IPEN/T<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

O desenvolvimento industrial e urbano tem causado aumento mundial das emissões de poluentes atmosféricos. Nas áreas metropolitanas o problema da deterioração da qualidade do ar tem se constituído numa das mais graves ameaças à qualidade de vida dos seus habitantes e os veículos automotores contribuem diretamente com o aumento do material particulado (MP). Neste trabalho foram descritas as etapas metodológicas para validar a Tibouchina granulosa como biomonitor ambiental. Assim, foram abordados a caracterização das folhas, categorização do MP, protocolo de remoção de MP e determinação dos EGPs (Pd, Pt e Rh) na deposição seca das folhas. Para tanto foram realizadas quatro coletas anuais (2011-2014) de folhas, entre os meses de agosto e setembro, em pontos específicos. Os resultados da caracterização mostraram que as folhas permanecem residentes nos ramos por até 6 meses e ocorre o desenvolvimento duas novas folhas por nó a cada mês, indicando que o biomonitoramento pode ser realizado com distribuição temporal e espacial. Os caracteres anatômicos foliares mais relevantes são os tricomas, sendo caracterizados quatro tipos (glandular, adpresso-escabro, base ramificada e estrigoso) que adsorvem o MP. No protocolo de remoção da deposição seca, o número de MP variou de acordo com os diferentes reagentes analíticos utilizados, sendo os mais significativos o ALCONOX&reg e a água régia, que apresentaram valores de remoção na faixa de 99-98% e de 94-99%. As estimativas das incertezas analíticas dos EGPs apresentam valores de uCPt=5% (Pt), uCPd=12% (Pd) e uCRh=5% (Rh) e as incertezas de amostragem, os valores de 57% para o Pd, 24% para a Pt e 27% para o Rh. Portanto, a incerteza expandida foi da Pt U=48%, Pd U=86% e Rh U=9%, a incerteza do Rh apresentou valor mais baixo por ser o elemento minoritário. A elevada sensibilidade do método para determinação dos EGPs apresentou limite de detecção de 0,1 pg g-1 para o Pd, 1,3 pg g-1 para Pt e 0,3 pg g-1 para o Rh e acompanhada boa reprodutibilidade. As concentrações dos EGPs encontradas na deposição seca nos vários pontos de coletas indicaram a clara diferença de acúmulo destes elementos entre o ponto de referência e os locais impactados, sugerindo que a liberação dos EGPS pelos catalisadores veiculares pode ser considerada alta. A evidência da presença dos EGPs na deposição seca foi confirmada por meio da análise da distribuição, que mostrou claramente a similaridade com o material de referência certificado Used Auto Catalystc-2557. As distribuições espaciais dos EGPs foram semelhantes para a Coleta 2, indicando os hot points da RMSP. As concentrações do EGPs foram ordenadas em Pt>Pd>Rh e foram mais baixas no ponto de coleta para controle das amostragens em comparação com os outros locais amostrados. Pode ser concluído que as folhas de T. granulosa foram validadas como biomonitor passivo dos EGPs constituintes de catalisadores veiculares.<br>Industrial and urban development has caused worldwide increase in emissions air pollutants. In metropolitan areas, the problem of deterioration air quality has been one the most serious threats to quality life its inhabitants, motor vehicles contribute directly increase pollutants. This work describes the methodological steps to validate Tibouchina granulosa as environmental biomonitor, which involved the characterization the leaves, PM categorization, PM removal protocol and determination PGEs in dry deposition, for which four annual collections (2011-2014) were performed between August and September of each year. The of results leaf characters showed that leaves in the branches remain for up to 6 months and the development two new leaf occurs every month. The most relevant foliar characters anatomical are trichomes, being characterized five types. The highest particle concentrations adsorbed to stray trichomes and star-based trichomes. In dry deposition removal protocol, MP number varied according to different analytical reagents used, the most significant being ALCONOX&reg and aqua regia, which presented range removal values of 99-98% and 94-99%, respectively. The estimates analytical uncertainties PGEs show de uCPt=5% (Pt), uCPd=12% (Pd) e uCRh=5% (Rh) and sampling uncertainties values were 57% (Pd), 24% (Pt) and 27% (Rh). Therefore, the expanded uncertainty was Pt u=48%, Pd u=86% e Rh u=9%, in case Rh the uncertainties should be reevaluated by presenting minority values. The high sensitivity of the method for determination of PGEs showed a detection limit of 0.1 pg g-1 for Pd, 1.3 pg g-1 for Pt and 0.3 pg g-1 for Rh and good reproducibility of the results. The concentrations PGEs found in dry deposition in various collection points indicated the clear difference accumulation these elements between reference point and impacted sites, suggesting that release PGEs by the vehicle catalysts can be considered high. Confirming this evidence, through the ternary graphs, which clearly showed similar distributions in the environmental samples and equality with MRC (Used Auto Catalysts). The spatial distributions of Pt, Pd and Rh are similar for Collection 2. Concentrations of the PGEs were ordered in Pt>Pd>Rh and were lower at the collection points for control samplings compared to other sites sampled. In view of the above, it can be concluded that the leaves of T. granulosa can be used as environmental biomonitor of vehicular emissions of PGEs constituent of vehicular catalysts.

The thesis is specialized on a possibility of measuring qualities and availability of a cellular radio system and also on evaluation qualities, fruitfulness interface, permeability etc. It includes short description of a basic mobile technology. Further analysis of the possibility of measuring the mobile network and how implement the measure. It also includes a draft program for measuring and evaluation of the GSM network with help several tests by a mobile phone connected through the Bluetooth.

Adaptive antenna systems (AAS's) are traditionally of interest only in radar and sonar applications. However, since the onset of the explosive growth in demand for wireless communications during the 1990's, researchers are giving increasing attention to the use of AAS technology to overcome practical challenges in providing the service. The main benefit of the technology lies in its ability to exploit the spatial domain, on top of the temporal and frequency domains, to improve on transceiver performance. This thesis presents a unified study on two classes of preprocessing techniques for uniform circular arrays (UCA's). UCA's are of interest because of their natural ability to provide a full azimuth (i.e. 360') coverage found in typical scenarios for sensor array applications, such as radar, sonar and wireless communications. The two classes of preprocessing techniques studied are the Davies transformation and the interpolated array transformations. These techniques yield a mathematically more convenient form - the Vandermonde form - for the array steering vector via a linear transformation. The Vandermonde form is useful for different applications such as direction-of-arrival (DOA) estimation and optimum or minimum variance distortionless response (MVDR) beamforming in correlated signal environment and beampattem synthesis. A novel interpolated array transformation is proposed to overcome limitations in the existing interpolated array transformations. A disadvantage of the two classes of preprocessing techniques for UCA's with omnidirectional elements is the lack of robustness in the transformed array steering vector to array imperfections under certain conditions. In order to mitigate the robustness problem, optimisation problems are formulated to modify the transformation matrices.Suitable optimisation techniques are then applied to obtain more robust transformations. The improved transformations are shown to improve robustness but at the cost of larger transformation errors. The benefits of the robustification procedure are most apparent in DOA estimation. In addition to the algorithm level studies, the thesis also investigates the use of AAS technology with respect to two different third generation (3G) mobile communications systems: Enhanced Data rates for Global Evolution (EDGE) and Wideband Code Division Multiple Access (WCDMA). EDGE, or more generally GSM/EDGE Radio Access Network (GERAN), is the evolution of the widely successful GSM system to provide 3G mobile services in the existing radio spectrum. It builds on the TDMA technology of GSM and relies on improved coding and higher order modulation schemes to provide packet-based services at high data rates. WCDMA, on the other hand, is based on CDMA technology and is specially designed and streamlined for 3G mobile services. For WCDMA, a single-user approach to DOA estimation which utilises the user spreading code and the pulse-shaped chip waveform is proposed. It is shown that the proposed approach produces promising performance improvements. The studies with EDGE are concerned with the evaluation of a simple AAS at the system and link levels.Results from, the system and link level simulations are presented to demonstrate the effectiveness of AAS technology in the new mobile communications system. Finally, it is noted that the WCDMA and EDGE link level simulations employ the newly developed COST259 directional channel model, which is capable of producing accurate channel realisations of macrocell environments for the evaluation of AAS's.

Adaptive antenna systems (AAS's) are traditionally of interest only in radar and sonar applications. However, since the onset of the explosive growth in demand for wireless communications during the 1990's, researchers are giving increasing attention to the use of AAS technology to overcome practical challenges in providing the service. The main benefit of the technology lies in its ability to exploit the spatial domain, on top of the temporal and frequency domains, to improve on transceiver performance. This thesis presents a unified study on two classes of preprocessing techniques for uniform circular arrays (UCA's). UCA's are of interest because of their natural ability to provide a full azimuth (i.e. 360') coverage found in typical scenarios for sensor array applications, such as radar, sonar and wireless communications. The two classes of preprocessing techniques studied are the Davies transformation and the interpolated array transformations. These techniques yield a mathematically more convenient form - the Vandermonde form - for the array steering vector via a linear transformation. The Vandermonde form is useful for different applications such as direction-of-arrival (DOA) estimation and optimum or minimum variance distortionless response (MVDR) beamforming in correlated signal environment and beampattem synthesis. A novel interpolated array transformation is proposed to overcome limitations in the existing interpolated array transformations. A disadvantage of the two classes of preprocessing techniques for UCA's with omnidirectional elements is the lack of robustness in the transformed array steering vector to array imperfections under certain conditions. In order to mitigate the robustness problem, optimisation problems are formulated to modify the transformation matrices.<br>Suitable optimisation techniques are then applied to obtain more robust transformations. The improved transformations are shown to improve robustness but at the cost of larger transformation errors. The benefits of the robustification procedure are most apparent in DOA estimation. In addition to the algorithm level studies, the thesis also investigates the use of AAS technology with respect to two different third generation (3G) mobile communications systems: Enhanced Data rates for Global Evolution (EDGE) and Wideband Code Division Multiple Access (WCDMA). EDGE, or more generally GSM/EDGE Radio Access Network (GERAN), is the evolution of the widely successful GSM system to provide 3G mobile services in the existing radio spectrum. It builds on the TDMA technology of GSM and relies on improved coding and higher order modulation schemes to provide packet-based services at high data rates. WCDMA, on the other hand, is based on CDMA technology and is specially designed and streamlined for 3G mobile services. For WCDMA, a single-user approach to DOA estimation which utilises the user spreading code and the pulse-shaped chip waveform is proposed. It is shown that the proposed approach produces promising performance improvements. The studies with EDGE are concerned with the evaluation of a simple AAS at the system and link levels.<br>Results from, the system and link level simulations are presented to demonstrate the effectiveness of AAS technology in the new mobile communications system. Finally, it is noted that the WCDMA and EDGE link level simulations employ the newly developed COST259 directional channel model, which is capable of producing accurate channel realisations of macrocell environments for the evaluation of AAS's.

碩士<br>國立清華大學<br>通訊工程研究所<br>89<br>TCP congestion control \cite{JacV.98} has been widely discussed on the different networks under wireline or wireless environment. Many research studies have been raised to help TCP be more sensitive to congestion state of the network by adding explicit notifications in TCP connection or letting the intermediate in the network to join TCP congestion control. In GPRS/EGPRS systems and other 3G cellular networks, the radio network controller chooses among several channel coders according to the signal to interference ratio. Hence, the channel data rate that an individual user experiences is time-dependent and variable. In this paper, we propose a TCP window control mechanism that adapts to the variable channel data rates. Our simulations show that the rate adaptive window adjustment scheme decreases the buffer occupancy and packet transmission delay, and achieves better throughput utilization when compared with the standard TCP Tahoe version and the Reno version.

WLANs provide high speed services but the radio coverage is small and does not support good mobility performance as compared to cellular systems. In this thesis, an integrated network of GPRS and wireless LAN is presented and a handoff algorithm is proposed for the integrated network. Handoff is an important issue when considering mobility in an integrated wireless communication network. The objective of the algorithm is to achieve seamless network service coverage and maximum data transfer speed. Traditional cellular GPRS/EGPRS networks can provide good mobility performance but relatively low speed data service. In the proposed handoff algorithm, the mobile station can camp on the best serving access point based on its geographic position and moving speed. Accessing a WLAN network, if possible, has a higher priority than accessing GPRS/EGPRS cellular network. To achieve a comprehensive performance investigation, a simulation is implemented based on a large traffic load. Simulation results show the performance characteristics and functionalities of the algorithm that includes total throughput, call successful rate, call block rate, packet error rate, handoff rate and resource utilization. Simulation results demonstrate that the proposed handoff algorithm achieves higher throughput and call successful rate than the traditional cellular network. The optimization of the deployment of access points of the integrated network is also investigated.

碩士<br>國立清華大學<br>資訊工程學系<br>89<br>Various next generation cellular systems are under development or deployment in order to meet rapidly increasing demand for high-speed wireless communications all over the world. Among them, EGPRS is a TDMA system evolved from GSM. By adopting EDGE air interface and supporting packet mode radio, EGPRS system can supply high data rate and improve system capacity significantly without requiring additional spectrum. NTHU and AT&T Labs have jointly developed an EGPRS test bed since last September for the purpose of investigating the performance of EGPRS system and studying QoS scheduling algorithms. This thesis is focused on implementation of a real-time emulated RLC layer for the EGPRS test bed. The design of the emulated RLC layer is based on a Radio Markov Model that was drawn from intensive offline system simulations for thousands of mobile users. Using the Radio Markov Model, time-varying wireless channels can be emulated in real-time by the RLC layer. A multi-queue based MAC layer scheduling algorithm is included in the RLC layer, which can assure QoS for real-time packet voice even if heavy burst data background traffic is presented. The RLC layer is programmed on Linux system as a virtual network interface device driver, which is independent of the Linux IP stack and thus making it easy for the EGPRS test bed to introduce IP-layer scheduling algorithms for QoS issues in EGPRS core networks. As a conclusion of this thesis, an experiment is conducted on the EGPRS test bed to demonstrate performance difference of real-time voice conversation between the case of multi-queue based MAC layer scheduling and that of single-queue routing. Some kernel parameters output from the RLC layer are presented in the thesis, which shows clearly that the multi-queue based MAC layer scheduling is necessary in order to assure QoS of real-time voice applications.

The development of GSM is currently focused on packet-switched services. The first solution to provide such services is known as General Packet Radio Service (GPRS), which has been deployed commercially. A further step comes with Enhanced General Packet Radio Service (EGPRS). To improve the capacity and achieve more efficient utilization of the frequency spectrum of cellular systems, the Space Division Multiple Access (SDMA) using smart antenna has drawn wide attention in recent years. However, its application, especially on GSM/EGPRS network, still needs further investigation. This work aims to evaluate the performance of the GSM/EGPRS cellular network employing SDMA, together with a complete Dynamic Channel Allocation (DCA) strategy, from various perspectives. Simulation results show that SDMA can greatly increase the system capacity, and that the data rate, the distribution of users, the propagation environments, the channel assignment schemes, the antenna sidelobe levels and the buffersize of users all have great influence on the performance of the EGPRS network with SDMA.

With the increasing demand for information anywhere, any time, wireless data service is becoming more important than before. In 2G mobile cellular systems, emphasis is put on circuit-switched voice services that can only supply limited data services, which cannot meet nowadays data requirement. To meet the new challenge, 2G mobile cellular systems have taken an evolutionary approach in developing data based services, which is referred to 2.5G or 2.75G. GPRS, EGPRS and EDGE are standardized by European Telecommunications Standards Institute (ETSI) and belong to 2.5G-2.75G standard. GPRS is only used for packet data service instead of voice traffic. In fact in a cell that supports GPRS, both GSM and GPRS systems operate in parallel to provide service for packet data and voice traffic. EDGE Phase one focuses on the non-real-time packet data services. This is also called EGPRS. The EDGE Phase Two aims at providing both real-time services such as voice and video delivering and non-real-time services in an end-to-end packet mode. To provide various services and to achieve more efficient utilization of the scarce frequency spectrum, research on radio resource allocation is becoming a hot topic. To evaluate the advantage of dynamic resource allocation, the performances of fixed and dynamic resource allocation are compared in this thesis. To simulate various services, four different data rate classes, and four different traffic models are assumed. The result i of the simulations show that: the Dynamic Resource Allocation Scheme can bring much better performance improvement than the Fixed Resource Allocation Scheme. At the same average data rate and the same variance, the performance is the same and does not change with the traffic model. The resource allocation schemes show robustness to different traffic models.

Enhanced General Packet Radio Services (EGPRS) is one of the proposals for third-generation (3G) wireless services. EGPRS is also the evolutionary path for GSM and IS-136 standards towards their next-generation wireless systems. The 3G services are categorized into the background, conversational, interactive and streaming services. Therefore, GSM towards 3G is staged into two phases. The phase one of EGPRS to provide Internet access services is known as General Packet Radio Service (GPRS). The phase two of EGPRS to provide 3G services integrates with the Enhanced Data rates for the GSM Evolution (EDGE). To provide the various 3G services and to achieve more efficient utilization of the frequency spectrum, our work is to focus on, the evolution of the system capacity and performance for the GSM/EGPRS networks. Therefore, an Adaptive Resource Assignment along with Overload Control (ARAOC) algorithm has been developed while integrating adaptive channel allocation, call admission control, frequency hopping and new congestion control schemes. Our simulation results show that this algorithm can greatly improve the system capacity and performance as well as the QoS for users. The influence of the variable parameters of user data rates, channel buffer size, and channel assignment parameter to the system capacity and performance, will be investigated.

碩士<br>國立成功大學<br>地球科學系碩士在職專班<br>107<br>The Chishan fault and Longchuan fault have moved obviously in recent years, and the motion caused the deformation of the viaduct and the Jungliau tunnel. Geodetic data were collected about one year before and after the 2016 Meinong earthquake from 43 continuous GPS stations in southwestern Taiwan area. At Jungliau tunnel area, 7 points within a length of about 3.6 km were setup crossing the Longchuan fault and Chishan fault. Ten measurements with about once a week were surveyed by using e-GPS from January to April 2017 for understanding the horizontal and vertical velocity field of the study area. After the 2016 Meinong earthquake, crustal deformation of southwestern Taiwan increase to about over 50 mm/yr based on continuous GPS data. And the area between the Longchuan and Chishan faults, the crustal deformation here was larger than the other area. Except for possible lateral extrusion motion here, it might have the other forces contributing this motion. After the Meinong earthquake, the crustal deformation here also increased. At the same point, the horizontal velocity increased from 100 mm/yr to 115 mm/yr, the vertical velocity increased from 79 mm/yr to 141 mm/yr, about 180% larger. Jungliau tunnel area has no obvious crack on building and ground surface after the Meinong earthquake, so the growth of surface deformation might be caused by other forces like mud diapir.