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 / 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

<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>

Techn., Hochsch., Diss.--Aachen, 2007.

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. 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. 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>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>

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. 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. 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. 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. Additionaly, some suggestions are given in order to enhance performance, both by changing the EGPRS system and by modifying the TCP algorithms and parameters.

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.

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.