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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Analysis of Wideband Code Division Multiple Access (WCDMA) system with co-channel interference

Argyros, Andreas 09 1900 (has links)
Approved for public release; distribution is unlimited. / The Wideband Code Division Multiple Access is a third generation air interface, initiated in European Union research projects at the start of the 1990s. The standard emerged by the end of 1999 as part of the 3GPP standardization process. It was designed to support multiple simultaneous services with high quality services through an increased data rate. This research examines the properties and parameters of the WCDMA system to determine the feasibility of intercepting and exploiting this technology with known assets. It explores this possibility by looking at link analysis, adaptive antennas and co-channel interference canceling techniques to determine if the interception of WCDMA signals is possible. / Lieutenant Junior Grade, Hellenic Navy
12

System and circuit design techniques for WLAN-enabled multi-standard receiver

Zhang, Ling 22 November 2005 (has links)
No description available.
13

Efficiency Enhancement of Base Station Power Amplifiers Using Doherty Technique

Viswanathan, Vani 13 May 2004 (has links)
The power amplifiers are typically the most power-consuming block in wireless communication systems. Spectrum is expensive, and newer technologies demand transmission of maximum amount of data with minimum spectrum usage. This requires sophisticated modulation techniques, leading to wide, dynamic signals that require linear amplification. Although linear amplification is achievable, it always comes at the expense of efficiency. Most of the modern wireless applications such as WCDMA use non-constant envelope modulation techniques with a high peak to average ratio. Linearity being a critical issue, power amplifiers implemented in such applications are forced to operate at a backed off region from saturation. Therefore, in order to overcome the battery lifetime limitation, a design of a high efficiency power amplifier that can maintain the efficiency for a wider range of radio frequency input signal is the obvious solution. A new technique that improves the drain efficiency of a linear power amplifier such as Class A or AB, for a wider range of output power, has been investigated in this research. The Doherty technique consists of two amplifiers in parallel; in such a way that the combination enhances the power added efficiency of the main amplifier at 6dB back off from the maximum output power. The classes of operation of power amplifier (A, AB, B, C etc), and the design techniques are presented. Design of a 2.14 GHz Doherty power amplifier has been provided in chapter 4. This technique shows a 15% increase in power added efficiency at 6 dB back off from the compression point. This PA can be implemented in WCDMA base station transmitter. / Master of Science
14

Characterization of Uplink Transmit Power and Talk Time in WCDMA Networks

Bhupathi Raju, Arjun 12 September 2008 (has links)
As 3G handset manufacturers add more and more features such as multimedia applications, color displays, video cameras, web browsing, gaming, WLAN, and MP3 players, the current consumption of a handset is ever increasing. Of the many components, the RF power amplifiers receive the most attention as they draw significant battery current and continue to represent the largest power load on the battery. In order to improve the overall efficiency of a power amplifier, it is important to know the operating uplink transmit power levels of a mobile phone in the WCDMA network. The work in this thesis makes two major contributions. First is the characterization of uplink transmit power in WCDMA networks based on current network data (collected in AT&T's WCDMA network) and realistic usage scenarios. Second is an investigation of the relationship between the battery life and the probability distribution function of the transmit power. Another important finding is that the talk time estimates using field tests, lab testing and theoretical expressions all give results to within 5%. Based on these data, design goals for WCDMA power amplifiers (in order to improve the talk times significantly) are suggested. The output power levels where the PA efficiencies have to be improved in order to significantly increase the battery life of WCDMA handsets are presented. / Master of Science
15

Contribution to wireless access optimization and dynamic enhancement of WCDMA networks

García Lozano, Mario 12 January 2009 (has links)
El despliegue de las redes celulares 3G/3.5G plantea un reto a las estrategias de planificación y optimización radio tradicionales. A diferencia de los sistemas 2G FDMA, cobertura y capacidad están estrechamente ligadas y deben ser tratadas conjuntamente. Además, están presentes nuevos y más sofisticados algoritmos de gestión de recursos radio (RRM) así como una concepción de red más flexible, con múltiples parámetros interdependientes con ajuste no trivial. Un nuevo paradigma de planificación radio aparece y la red se optimiza mediante complejos algoritmos ya sea estática o dinámicamente. Esta tesis doctoral supone una contribución a la optimización de las redes de acceso radio en sistemas 3G/3.5G. Varios aspectos susceptibles de mejorar la planificación han sido investigados y nuevos métodos, directrices y estrategias de análisis se proponen con el objetivo final de mejorar el rendimiento del sistema. También se han diseñado y estudiado mecanismos dinámicos que se encuentran en la frontera difusa entre la planificación y la RRM. La 1ª parte de la tesis trata la configuración de las estaciones base. El impacto de las potencias piloto, inclinación de antenas y sus interacciones con parámetros de soft handover son investigados. Se hace énfasis en los efectos más allá de los conocidos y se derivan reglas para su ajuste. A partir de los resultados, se propone una estrategia para su Planificación Automática. El objetivo final es encontrar una combinación tal que el tráfico sea ecualizado de manera efectiva entre las celdas e incrementar la capacidad del sistema. La técnica se basa en la metaheurística Simulated Annealing y es capaz de mejorar el rendimiento global de la red, representado por una función de coste con información sobre el factor de carga y sujeta a otras condiciones de calidad. La importancia de los requisitos que impone el UL, a menudo olvidados en propuestas anteriores, también se ha incluido y estudiado analíticamente. La reconfiguración de las base no es el único medio para modificar la cobertura de las celdas, en este sentido el estudio se amplía mediante la introducción de repetidores, que permiten la generación de celdas distribuidas. En este caso la planificación es más compleja debido a la aparición de nuevos efectos que no se daban en las redes clásicas 2G FDMA. La mayoría de los trabajos que tratan con repetidores tienden a ignorarlos. Por ello, la investigación se centró en el modelado y cuantificación de su impacto así como en derivar directrices de planificación. Se ha obtenido analíticamente la nueva expresión que define la región de admisión y se concluye que existe un compromiso entre capacidad y cobertura, analizado tanto teóricamente como mediante simulación. Ciertos parámetros presentan un impacto importante y se han estudiado para obtener reglas prácticas de ajuste. La variación de cobertura en la celda padre antes y después de la instalación de repetidores también ha sido modelada. Posteriormente, se propone una nueva metodología para analizar estos despliegues, teniendo en cuenta de manera realista los retardos de propagación y el comportamiento del receptor Rake. Esto permite un análisis superior con respecto a enfoques tradicionales que, en determinadas circunstancias, tienden a ofrecer cifras erróneamente optimistas. La última parte de la tesis da un paso más en la Planificación Automática y se proponen y validan 2 mecanismos dinámicos que permiten a la red reaccionar y auto-optimizarse frente a cambios en las condiciones de tráfico. El primero, basado en conclusiones anteriores, persigue detectar si uno de los enlaces presenta problemas de capacidad y, en caso afirmativo, favorecerlo para retrasar los mecanismos de control de congestión. Por último, se introduce la tecnología HSDPA y, después de analizar los recursos que deben ser compartidos con versiones previas de UMTS, se concluye que es deseable un sistema para la gestión dinámica del árbol de códigos OVSF. Se propone y valida un mecanismo que maximiza el throughput de las celdas, garantizando al mismo tiempo criterios de bloqueo y dropping. / The deployment of 3G/3.5G cellular networks challenges traditional radio planning and optimization strategies. Unlike FDMA based 2G systems, coverage and capacity are tightly coupled and must be treated as a whole. Besides new and more sophisticated Radio Resource Management (RRM) algorithms are present along with a more flexible network with many interdependent parameters, whose joint adjustment is not trivial. A new radio planning paradigm appears in which the radio network is optimized by means of complex algorithms both in a static and a dynamic way. This Ph.D. thesis provides a contribution to the radio network optimization of 3G/3.5G networks. Several issues to improve radio network planning have been investigated and new methods, guidelines and strategies of analysis have been proposed with the final objective of enhancing the wireless access network performance. Dynamic mechanisms being in the blurred line between radio planning and RRM are also devised and studied. The first part of this dissertation deals with the configuration of Base Stations (BSs) the impact of pilot powers, downtilt of antennas and interactions thereof with Soft Handover parameters are investigated. Effects beyond well-known facts are outlined and new planning guidelines are derived. Given the results, an Automatic Planning strategy is devised to automate the configuration of these parameters and to find a combination such as traffic is effectively equalized among cells and a higher capacity is achieved. The technique is based on the Simulated Annealing metaheuristic and is able to improve the global performance of the network, represented by a cost function containing information on the load factor and subject to other quality constraints. The importance of uplink (UL) requirements, usually missed by existent proposals, has been also included and analytically addressed. Reconfiguring BSs is not the only means to modify cell shapes, in this sense the study is extended by introducing repeaters, which allow generating distributed coverage areas. This is the context of the second part of the thesis. New effects not present in FDMA based 2G systems imply that the radio planning process becomes more complex. Most existent papers dealing with repeaters in WCDMA networks, ignore these effects or claim their irrelevance. That is why the research work was focused in modeling them, quantifying their impact and deriving radio planning guidelines to enhance the final performance of the radio access network. The new expression for the feasibility condition has been analytically obtained showing a tradeoff between capacity and coverage. This has been analyzed both theoretically and by means of simulations and the adjustment of several parameters which have a significant impact is discussed to derive practical rules of thumb. Variation on the coverage of the donor cell before and after installing repeaters is also modeled. Subsequently, it is proposed a new methodology to analyze WCDMA networks with repeaters deployment, considering realistically path delays and the behavior of Rake receivers. This allows an enhanced analysis with respect to traditional approaches which, under certain circumstances, tend to provide erroneously optimistic metrics. The final part of the dissertation goes one step further in Automatic Planning and two dynamic mechanisms are proposed and validated so that the network can react and self tune in front of changes in traffic conditions. The first one follows some previous conclusions and aims at detecting if one of the links has capacity problems and if so, favors it to delay congestion control actions. Finally, HSDPA technology is introduced and, after analyzing the resources to be shared with a previous release of UMTS, it is concluded that a system that dynamically manages the OVSF code tree is desired. A mechanism aiming at maximizing cell throughput while guaranteeing blocking and dropping criteria is proposed and validated.
16

COMPATIBILITY OF IRIG-106-00 STANDARDIZED FEHERPATENTED FQPSK WITH OTHER DATA LINKS AND WIDEBAND W-CDMA

McCorduck, James A., Feher, Kamilo 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / The interoperability of Feher-patented Quadrature Phase Shift Keying (FQPSK) systems with future and legacy data links is discussed in this paper. In particular, the benefits of “forward” interoperability with 3G (3rd Generation) wireless systems such as WCDMA (Wideband Code Division Multiple Access) up to 40 Mchips/sec are highlighted. Other proposals of forward interoperability with future data links include an enhanced, ultra-bandwidth efficient FQPSK and 16-state FQAM (Feher’s Quadrature Amplitude Modulation) architectures. In addition, since FQPSK based systems have been proven in “dual use” systems and extensively tested and evaluated by the Department of Defense (DoD) and NASA, the analysis of “backward” interoperability with legacy data links such as GSM is also included in this paper.
17

Improving mobile IP handover latency on end-to -end TCP in UMTS/WCDMA networks

Lau, Chee Kong, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 2006 (has links)
Due to terminal mobility and change of service area, efficient IP mobility support is an important aspect in UMTS networks in order to provide mobile users negligible packet loss rate and low handover latency, and thus some level of guaranteed quality-ofservice (QoS) to support real-time applications. 3G/UMTS has been specified and implemented as an end-to-end mobile communications system. The underlying WCDMA access systems manage radio access handover (layer 1) and provide linklayer mobility (layer 2) in terms of connection setup and resource management. For the UMTS nodes to have seamless connectivity with the Internet, the UMTS core networks need to be able to support continuous and no network service session handover (layer 3 and above). A long IP handover latency results in high packet loss rate and severely degrades its end-to-end transport level performance. Network-layer handover latency has therefore been regarded as one of the fundamental limitations in IP-based UMTS networks. Therefore, it is crucial to provide efficient network-layer mobility management in UMTS/WCDMA networks for seamless end-to-end TCP connection with the global Internet. Mobility of UMTS nodes necessitates extra functionalities such as user location tracking, address registration and handover related mechanisms. The challenge to provide seamless mobility in UMTS requires localised location management and efficient IP handover management. Mobile IPv6 protocol offers a better mobility support as the extended IPv6 features with mobility mechanism are integrated to the mobile nodes. To mitigate the effect of lengthy IP handover latency, two well-known handover reducing mechanisms based on Mobile IPv6 support have been proposed in the literature. They are designed with hierarchical network management and address pre-configuration mechanism. Hierarchical management aims to reduce the network registration time, and fast-handover attempts to minimise the address resolution delay. S-MIP (Seamless Mobile IP) integrates the key benefits of the above IP mobility mechanisms coupled with local retransmission scheme to achieve packet lossless and extremely low handover latency, operating in WLAN environments. In this thesis, we explore the possible Mobile IP solutions and various IP handover optimisation schemes in IPv6 to provide seamless mobility in UMTS with the global Internet. It aims at developing an optimised handover scheme that encompasses the packet lossless and extremely low handover latency scheme in S-MIP, and applying it into the UMTS/WCDMA packet data domain. Therefore, the hybrid UMTS-SMIP architecture is able to meet the requirements of delay sensitive real-time applications requiring strict delay bound, packet lossless and low handover latency performance for end-to-end TCP connection during a UMTS IP-based handover. The overall seamless handover architecture in UMTS facilitates integrated, scalable and flexible global IP handover solution enabling new services, assuring service quality and meeting the user???s expectations in future all-IP UMTS deployment. The viability of the seamless mobility scheme in UMTS is reflected through and validated in our design model, network protocol implementation, and service architecture. We illustrate the performance gained in QoS parameters, as a result of converged UMTS-SMIP framework compared to other Mobile IPv6 variants. The simulation results show such a viable and promising seamless handover scheme in UMTS on IP handover latency reduction on its end-to-end TCP connection.
18

Quality of Heterogeneous Services with Distributed Resource Management for a WCDMA Uplink

Das, Pratik January 2006 (has links)
A radio resource management scheme for WCDMA uplinks is proposed that manages quality of service (QoS) for heterogeneous services whilst maintaining high channel utilisation efficiency. The proposed system is partitioned into the 3 modules, viz. a QoS-sensitive rate scheduler, an inter-service and intra-service user prioritisation schemes, and a frame admission controller for dynamic resource reallocation. Users are allocated the minimum resources required to manage their QoS requirements through just-in-time delivery of payload, leaving more room for best-effort service users. The transmission urgency of each user is estimated by the rate scheduler based on a target transmission delay - a unique parameter used in the proposed resource management strategy to enable just-in-time payload delivery, service differentiation, and uncomplicated mapping of application requirements to QoS parameters. Transmission rate change requests from the rate schedulers are collectively processed through inter-service and intra-service priority queuing in a manner that is shown to exhibit fairness in allocation of resources amongst users of a heavily loaded network. The performance of the proposed strategy is explored through discrete-event simulations for 3 classes of traffic - voice, video and data, over the WCDMA uplink in the presence of short-term Rayleigh fading, ARQ, FEC, target transmission delays and FER targets in a multi-cell environment. Two alternatives for distributed resource management have been studied, with the UE or Node-B in control of resource allocation. The UE controlled resource management system is shown to achieve higher channel utilisation efficiency at the cost of fairness. The Node-B controlled resource manager respects the priority of speech, video and data traffic in heavily loaded systems, as reflected in 95 percentile packet transmission delays. / PhD Doctorate
19

Improving mobile IP handover latency on end-to -end TCP in UMTS/WCDMA networks

Lau, Chee Kong, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 2006 (has links)
Due to terminal mobility and change of service area, efficient IP mobility support is an important aspect in UMTS networks in order to provide mobile users negligible packet loss rate and low handover latency, and thus some level of guaranteed quality-ofservice (QoS) to support real-time applications. 3G/UMTS has been specified and implemented as an end-to-end mobile communications system. The underlying WCDMA access systems manage radio access handover (layer 1) and provide linklayer mobility (layer 2) in terms of connection setup and resource management. For the UMTS nodes to have seamless connectivity with the Internet, the UMTS core networks need to be able to support continuous and no network service session handover (layer 3 and above). A long IP handover latency results in high packet loss rate and severely degrades its end-to-end transport level performance. Network-layer handover latency has therefore been regarded as one of the fundamental limitations in IP-based UMTS networks. Therefore, it is crucial to provide efficient network-layer mobility management in UMTS/WCDMA networks for seamless end-to-end TCP connection with the global Internet. Mobility of UMTS nodes necessitates extra functionalities such as user location tracking, address registration and handover related mechanisms. The challenge to provide seamless mobility in UMTS requires localised location management and efficient IP handover management. Mobile IPv6 protocol offers a better mobility support as the extended IPv6 features with mobility mechanism are integrated to the mobile nodes. To mitigate the effect of lengthy IP handover latency, two well-known handover reducing mechanisms based on Mobile IPv6 support have been proposed in the literature. They are designed with hierarchical network management and address pre-configuration mechanism. Hierarchical management aims to reduce the network registration time, and fast-handover attempts to minimise the address resolution delay. S-MIP (Seamless Mobile IP) integrates the key benefits of the above IP mobility mechanisms coupled with local retransmission scheme to achieve packet lossless and extremely low handover latency, operating in WLAN environments. In this thesis, we explore the possible Mobile IP solutions and various IP handover optimisation schemes in IPv6 to provide seamless mobility in UMTS with the global Internet. It aims at developing an optimised handover scheme that encompasses the packet lossless and extremely low handover latency scheme in S-MIP, and applying it into the UMTS/WCDMA packet data domain. Therefore, the hybrid UMTS-SMIP architecture is able to meet the requirements of delay sensitive real-time applications requiring strict delay bound, packet lossless and low handover latency performance for end-to-end TCP connection during a UMTS IP-based handover. The overall seamless handover architecture in UMTS facilitates integrated, scalable and flexible global IP handover solution enabling new services, assuring service quality and meeting the user???s expectations in future all-IP UMTS deployment. The viability of the seamless mobility scheme in UMTS is reflected through and validated in our design model, network protocol implementation, and service architecture. We illustrate the performance gained in QoS parameters, as a result of converged UMTS-SMIP framework compared to other Mobile IPv6 variants. The simulation results show such a viable and promising seamless handover scheme in UMTS on IP handover latency reduction on its end-to-end TCP connection.
20

WCDMA User Equipment Output Power Calibration / Uteffektskalibrering för WCDMA-telefon

Folkeson, Tea January 2003 (has links)
<p>To save time in Flextronics high volume production, the time for test and calibration of mobile telephones need to be as short and accurate as possible. In the wideband code division multiple access (WCDMA) case, the output power calibration is the most critical calibration concerning accuracy. The aim with this thesis was to find a faster calibration method than the one that exists today and still retain accuracy. </p><p>The Third Generation Partnership Project (3GPP) outlines the requirements of the output power and they must be thoroughly considered when choosing calibration method. Measurement accuracy and the behavior of the transmitter chain parameters also must be considered. </p><p>The output power in the WCDMA phone studied is controlled by seven parameters. The parameters are characterized in this thesis, and are found to be too hardware dependent to be predicted or to be seen as predictions from each other. </p><p>Since no parameter predictions are possible it was stated that all parameters have to be measured, and a new way of measuring them in a faster way is proposed. The principle of the new measurement method is presented, and the implemented software is tested and evaluated. The new method mainly makes use of the spectrum analyzer zero span function. </p><p>The evaluation shows that the new method is faster than the original and retains accuracy. The measurement uncertainties even seem to diminish, which implicates decreased temperature dependence due to faster measurement time.</p>

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