With the growing demand for high-speed data transmission, the Institute of Electrical and Electronics Engineers (IEEE) study group, particularly IEEE 802.11, which focuses on Wireless Fidelity (Wi-Fi) technologies, has been actively pursuing advancements to meet these escalating requirements. One such endeavor is the exploration of Millimeter Wave (mmWave) communications. However, mmWave communications differ significantly from traditional communication systems, characterized by factors like high propagation loss, directivity, and susceptibility to blockage. These distinctive attributes present numerous challenges that must be addressed to fully exploit the potential of mmWave communications. The 802.11be amendment, which will be advertised as Wi-Fi 7, introduces several features that aim to enhance the capabilities of Wi-Fi. One of the main features introduced in this amendment is the Multi-Link Operation (MLO) which allows nodes to transmit and receive over multiple links concurrently. The objective of this project is to assess the performance of integrating MLO with an additional mmWave link in comparison to using a single mmWave link. The aim is to determine whether this combination can effectively address challenges within mmWave communications and consequently enhance throughput performance. Experimental simulations were conducted using an event-based Radio Access Technology (RAT) simulator, considering various scenarios and setups. These investigations examined the impact of factors such as link bandwidth, the number of links in MLO, on Wi-Fi performance. Our findings demonstrate the potential of combining MLO with an additional mmWave link, highlighting significant improvements in overall throughput. However, our results also reveal a link asymmetry problem that arises when integrating links with substantial differences in link capacity. This problem manifests in a specific region where the performance of MLO is not as well as that of using a single mmWave link. To address this issue, we propose a potential solution, which we thoroughly investigate through multiple simulations to assess its feasibility and effectiveness. / Med den växande efterfrågan på höghastighetsdataöverföring har IEEE:s studiegrupp, särskilt IEEE 802.11, som fokuserar på Wi-Fi-teknik, aktivt strävat efter att göra framsteg för att möta dessa eskalerande krav. En sådan strävan är utforskningen av mm-vågskommunikation. mm-vågskommunikation skiljer sig dock avsevärt från traditionella kommunikationssystem, som kännetecknas av faktorer som hög spridningsförlust, direkthet och känslighet för blockering. Dessa utmärkande egenskaper innebär många utmaningar som måste hanteras för att fullt ut utnyttja potentialen hos mm-vågskommunikation. Tillägget 802.11be, som kommer att marknadsföras som Wi-Fi 7, introducerar flera funktioner som syftar till att förbättra kapaciteten hos Wi-Fi. En av de viktigaste funktionerna i detta tillägg är MLO (Multi-Link Operation) som gör det möjligt för noder att sända och ta emot över flera länkar samtidigt. Syftet med detta projekt är att utvärdera hur MLO integreras med en extra mm-våglänk jämfört med en enda mm-våglänk. Målet är att fastställa om denna kombination effektivt kan hantera utmaningar inom mm-vågskommunikation och därmed förbättra genomströmningsprestandan. Experimentella simuleringar genomfördes med hjälp av en händelsebaserad RAT-simulator (Radio Access Technology), där olika scenarier och inställningar beaktades. I dessa undersökningar undersöktes hur faktorer som länkbandbredd och antalet länkar i MLO påverkar Wi-Fi-prestandan. Våra resultat visar potentialen i att kombinera MLO med ytterligare en mm-våglänk, med betydande förbättringar av den totala genomströmningen. Våra resultat visar dock också på ett länkasymmetriproblem som uppstår när man integrerar länkar med stora skillnader i länkkapacitet. Detta problem manifesteras i en specifik region där MLO:s prestanda inte är lika bra som vid användning av en enda mm-våglänk. För att ta itu med detta problem föreslår vi en potentiell lösning som vi undersöker grundligt genom flera simuleringar för att bedöma dess genomförbarhet och effektivitet.

[EN] Nowadays there are many works which analyze and seek to improve the performance of Wireless Local Area Networks (WLANs) from different perspectives. A great deal of them is focused on design aspects, such as frequency distribution or channel assignment. Therefore, as these features have already been widely studied, my efforts have been directed to study other conditions that also could affect their performance and that have not been analyzed in depth yet. The main goal of this Ph.D. dissertation has been to perform a detailed study that researches the weather's impact on the performance of WLANs IEEE 802.11b/g. Two different WLAN scenarios have been analyzed to validate the results and to find precise relations. From conclusions of these previous analysis, the second objective has been to design a cognitive protocol that based on weather conditions and network performance parameters, allows networks to adjust their transmission features in order to overcome such impact. In order to conduct this study, firstly it was necessary to study which statistical methods could be used to extract the level of correlation between performance parameters of networks and weather conditions running at the same time. Secondly, I had to know which performance parameters the outdoor WLAN of Universitat Politècnica de València (UPV) could provide, and select them according to my objective. Then, I defined the period of time in which these parameters were gathered periodically. The next step was to select and collect the weather conditions from a close weather station during the same period of time. Finally, I had to perform a detailed pre-processing to put all of the volume of data in order and data were statistically analyzed. Results were successful; however there were several problems due to the variability derived from a real WLAN scenario. Therefore, an experimental setup was required in order to check the obtained results. It entailed to design and to develop an outdoor point-to-multipoint IEEE 802.11b/g link and to analyze again the weather's impact. Multiple points were considered in order to take into account different distances in the performed evaluation and to examine the behavior of different modulation schemes working under the same weather conditions. From these results, a cognitive algorithm was designed in order to reduce the weather's impact on IEEE 802.11b/g networks. One key aspect was to ensure it was energy efficient. This protocol was simulated and the obtained results were satisfactory in terms of both energy efficiency and network performance. To conclude, other external factor to WLANs studied in this Ph.D thesis has been the specific absorption rate. It deals with a current public health worry because it is used to measure the body tissue exposure to electromagnetic fields. Obviously, signal absorption by human bodies affects to the performance of WLANs and so, this parameter should be also taken into account when deploying efficient networks. For this reason, this study has been also included in this thesis. / [ES] Hoy en día existen muchos trabajos que analizan e intentan mejorar el rendimiento de las redes de área local inalámbricas desde diferentes perspectivas. Gran parte de estos trabajos se centran en aspectos de diseño, como son la distribución de frecuencias o la asignación de canales. Por lo tanto, como estos aspectos ya han sido ampliamente estudiados, los esfuerzos de esta tesis se han dirigido a estudiar otros factores que también podrían afectar a su rendimiento y que no han sido analizadas en profundidad todavía. El objetivo principal de esta tesis doctoral ha sido realizar un estudio detallado que analice el impacto de las condiciones meteorológicas sobre el rendimiento de las redes IEEE 802.11b/g. Para realizar este estudio, se han analizado dos escenarios reales con el fin de verificar los resultados y encontrar relaciones precisas. A partir de las conclusiones de estos análisis previos, el segundo objetivo ha sido diseñar un algoritmo cognitivo que, en base a las condiciones meteorológicas y a los parámetros de rendimiento de red, permita a las redes ajustar sus características de transmisión con el fin de superar tal impacto. Con el fin de llevar a cabo este estudio, primero fue necesario estudiar qué métodos estadísticos podían ser utilizados para extraer el nivel de correlación entre los parámetros de rendimiento de las redes y las condiciones meteorológicas del entorno. En segundo lugar, se tuvo que analizar qué parámetros de rendimiento de red se podían extraer de la red exterior de la UPV y seleccionarlos de acuerdo con el objetivo perseguido. A continuación, se definió el periodo de tiempo durante el cual se almacenarían los parámetros seleccionados de forma periódica. El siguiente paso fue seleccionar y almacenar las condiciones meteorológicas de una estación cercana durante el mismo periodo de tiempo. Finalmente, se realizó un preprocesado detallado con el fin de poner en orden todo el volumen de datos y se analizaron estadísticamente. Los resultados fueron exitosos, sin embargo aparecieron varios problemas por el hecho de estudiar una red real muy variable. Por lo tanto, se tuvo que desarrollar un escenario experimental con el fin de verificar los resultados. Para ello se diseñó y desarrolló un enlace exterior IEEE 802.11b/g punto a multipunto, y se analizó de nuevo el impacto de las condiciones meteorológicas. Se consideró un enlace multipunto para analizar también cómo influía el impacto del tiempo según la distancia y los diferentes esquemas de modulación. A partir de los resultados, se diseñó un algoritmo cognitivo energéticamente eficiente con el fin de reducir el impacto de los fenómenos meteorológicos en las redes IEEE 802.11b/g. Dicho algoritmo ha sido simulado y los resultados obtenidos han sido satisfactorios, tanto en términos de eficiencia energética como de rendimiento de la red. Para concluir, otro factor externo que se ha estudiado en esta tesis ha sido la tasa de absorción específica. Este parámetro está relacionado con una de las grandes preocupaciones actuales en cuanto a salud pública, ya que se utiliza para medir la exposición de los tejidos del cuerpo humano a los campos electromagnéticos. Obviamente, la absorción de señal por parte del cuerpo humano afecta a las redes y, por lo tanto, este parámetro se debería tener en cuenta a la hora de diseñar redes eficientes. Por esta razón se ha incluido en esta tesis doctoral. / [CA] Actualment hi ha molts treballs que analitzen i intenten millorar el rendiment de les xarxes d'àrea local sense fils des de diferents perspectives. Gran part d'aquests treballs es focalitzen en aspectes de disseny, com són la distribució de freqüències o l'assignació de canals. Per tant, com aquests aspectes ja han sigut àmpliament estudiats, els esforços d'aquesta tesi doctoral s'han dirigit a estudiar altres factors que també podrien afectar al seu rendiment i que encara no han sigut analitzats amb profunditat. L'objectiu principal d'aquesta tesi doctoral ha sigut realitzar un estudi minuciós per analitzar l'impacte de les condicions meteorològiques sobre el rendiment de les xarxes IEEE 802.11b/g. Per a realitzar aquest estudi s'han analitzat dos escenaris reals per tal de verificar els resultats i trobar relacions precises. A partir de les conclusions d'aquests anàlisis previ, el següent objectiu ha sigut dissenyar un algoritme cognitiu que, en base a les condicions meteorològiques i als paràmetres de rendiment de la xarxa, permeti a les xarxes ajustar les seues característiques de transmissió per tal de superar tal impacte. Per tal de dur a terme aquest estudi, primer va ser necessari estudiar quins mètodes estadístics podien ser utilitzats per extraure el nivell de correlació entre els paràmetres de rendiment de les xarxes i les condicions meteorològiques de l'entorn. En segon lloc, es va haver d'analitzar quins paràmetres de rendiment es podien extraure de la xarxa exterior de la UPV i es van seleccionar d'acord a l'objectiu plantejat. A continuació, es va definir el període temporal al llarg del qual s'emmagatzemarien els paràmetres seleccionats de manera periòdica. El següent pas va ser seleccionar i emmagatzemar les condicions meteorològiques d'una estació propera durant el mateix període de temps. Finalment, es va realitzar un preprocessat per tal de posar en ordre tot el volum de dades i es van analitzar estadísticament. Els resultats van ser exitosos, però van aparèixer diversos problemes pel fet d'estudiar una xarxa real molt variable. Per tant, es va haver de desenvolupar un escenari experimental amb l'objectiu de verificar els resultats. Per aquesta raó es va dissenyar i implementar un enllaç exterior IEEE 802.11b/g punt a multipunt, i es va analitzar de nou l'impacte de les condicions meteorològiques. Es va considerar un enllaç multipunt per tal de d'analitzar també com influïa el impacte del temps segons la distància i els diferents esquemes de modulació. A partir d'aquests resultats, es va dissenyar un algoritme cognitiu energèticament eficient per tal de reduir l'impacte dels fenòmens meteorològics sobre les xarxes IEEE 802.11b/g. Aquest algoritme va ser simulat i els resultats obtinguts van ser satisfactoris, tant en termes d'eficiència energètica com de rendiment de la xarxa. va comprovar que la proposta aporta millores. Per concloure, un altre factor extern que s'ha estudiat en aquesta tesi doctoral ha sigut la taxa d'absorció específica. Aquest paràmetre està relacionat amb una de les preocupacions actuals pel que fa a la salut pública, ja que s'utilitza per a mesurar l'exposició dels teixits del cos humà als camps electromagnètics. Òbviament, aquesta absorció de la senyal afecta el rendiment de les xarxes i, per això, aquest paràmetre s'hauria de tenir en compte a l'hora d'implementar futures xarxes sense fils eficients. Per aquesta raó s'ha inclòs en aquesta tesi doctoral. / Bri Molinero, D. (2015). ESTUDIO DEL EFECTO DE FACTORES EXTERNOS SOBRE LAS REDES WLAN Y DISEÑO DE UN ALGORITMO COGNITIVO ENERGÉTICAMENTE EFICIENTE [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53450

This thesis examines an approach to directing Mac Wellman and David Lang’s opera, The Difficulty of Crossing a Field; in addition, the paper reflects on my artistic development as a Master of Fine Arts in Directing student in the Department of Theatre and Dance at the University of Texas at Austin. As a director I seek a balance between form and content. Similar to Installation Art, I consider the relationship between space/architecture (the stage/theatre) and sculpture, i.e., anything that can be used to create shape: performers, props, scenery, wardrobe, makeup, light, sound, music, language, etc. As a deviser, not a dictator, the success of my work depends greatly on interdisciplinary collaboration and strategies that promote understanding and appreciation among both artists and audiences. My aim is to create structures for formal elements that when arranged uniquely and sophisticatedly have the ability to provoke emotion, thought, and memory in vivid and compelling ways. This paper explores selected stages of directing The Difficulty of Crossing a Field, the strategies that I employed, and concludes with an artistic statement. / text

In recent years, Multi-hop Wireless Networks (MHWNs) have experienced an explosion of deployment due to the increasing demand for continuous connectivity regardless of the physical location. Internet predominant transport protocols, i.e. Transmission Control Protocol (TCP), face performance degradation in MHWNs because of the high loss and link failure rates. Several solutions have been proposed which are based on network state estimation or use information from MAC layer (called metrics) in a cross-layer manner to better comprehend the network state. The first part of this thesis provides a survey and comprehensive definition of common metrics from Physical, MAC, Network and Transport layers and thus provides a multi-criteria and hierarchical classification. After that, the effectiveness in reflecting network information of MAC metrics is also investigated in a systematic way by simulating various network situations and measuring the MAC metrics. Thus, the good MAC metric for congestion control which is coupled with the network contention level and the medium induced losses will be found out. From the results of the effectiveness study, new rate control schemes for transport protocols are proposed which adapt efficiently the source bit rate depending on the network condition provided by some MAC metrics. Through an extensive set of simulations, the performance of the proposed rate control schemes in MHWNs is investigated thoroughly with several network situations.

As camadas de enlace empregadas em redes sem fio de baixo custo e desempenho limitado, como as redes de sensores sem fio, são implementadas segundo o padrão IEEE 802.15.4. Prever o desempenho deste padrão é importante para analisar a viabilidade e o desempenho esperado de projetos envolvendo esse tipo de rede. Constatou-se que trabalhos anteriores com esse objetivo são incompletos no tocante às métricas aferidas e tem foco no cálculo de probabilidades, o que não faz parte da especificação do padrão. Assim, o objetivo deste trabalho foi projetar e implementar um modelo comportamental do padrão IEEE 802.15.4, cujos parâmetros possam ser facilmente alterados e que seja capaz de aferir as principais métricas de uma rede: vazão, taxa de entrega, atraso e gasto de energia. Os objetivos foram cumpridos com a validação do modelo perante simulação com o NS2. Além disso, o modelo foi utilizado para estudar a variação dos parâmetros aMaxFrameRetries, macMaxCSMABackos, initialCW e aUnitBackoPeriod do padrão IEEE 802.15.4, para estudar cenários em que os nós possuem tráfego assimétrico e cenários com diferentes relações de tamanho e taxa de chegada de pacotes, mantendo a taxa de bits constante. / Low cost and performance constrained wireless networks, such as wireless sensor networks, employ IEEE 802.15.4 standard as its MAC layer. Foreseeing this standard\'s performance is essential to analyze the feasibility and expected metrics results of these networks projects. It was observed that previous works with that aim are both incomplete regarding metrics of interest and focus on probability calculation, which is not part of the standard specication. Thus, the objective of this work is to project and implement a behavioral IEEE 802.15.4 standard model, which parameters may be easily set and that covers the main metrics of interest: throughput, delivery rate, delay and energy. The objectives were achieved, with model validation against NS2 simulations. Furthermore, the model was employed to analyze the performance variation caused by the parameters aMaxFrameRetries, macMaxCSMABackos, initialCW and aUnitBackoPeriod from the IEEE 802.15.4 standard and also scenarios with asymmetric trac conditions and packet size and arrival rate variations, maintaining a constant bitrate.

A proposta apresentada nesta dissertaÃÃo representa uma expansÃo do conceito original de assinatura em anel. Um esquema de assinatura em anel permite que um membro de um grupo divulgue uma mensagem anonimamente, de tal forma que cada um dos membros do grupo seja considerado o possÃvel autor da mensagem. A ideia principal de uma assinatura em anel à garantir o anonimato do assinante e ainda garantir a autenticidade da informaÃÃo, mostrando que a mensagem partiu de um dos membros do referido grupo. Esta dissertaÃÃo apresenta um esquema de assinatura em anel baseado no esquema de Rivest et al. (2001), em que o assinante pode, mais tarde, revogar seu anonimato apresentando valores secretos que provam que somente ele seria capaz de gerar tal assinatura. Esta propriedade serà chamada aqui de resgate de autoria. A principal diferenÃa em relaÃÃo ao trabalho de Rivest et al. (2001) à apresentada antes mesmo de comeÃar a geraÃÃo da assinatura. Os valores utilizados como entrada para a funÃÃo trapdoor serÃo cÃdigos de autenticaÃÃo de mensagem - MACs gerados pelo algoritmo HMAC, um algoritmo de autenticaÃÃo de mensagem baseado em funÃÃo hash resistente à colisÃo. Essa modificaÃÃo simples permitirà que, no futuro, o assinante revele-se como o verdadeiro autor da mensagem apresentando os valores secretos que geraram os MACs. / The proposal presented in this thesis represents an expansion of the original concept of ring signature. A ring signature scheme allows a member of a group to publish a message anonymously, so that each member of the group can be considered the author of the message. The main idea of a ring signature is to guarantee the anonymity of the subscriber also ensure the authenticity of information, showing that the message came from one of the members of that group. This thesis presents a signature scheme based on (RIVEST et al., 2001), where the subscriber can later revoke anonymity presenting secret values that prove that he would only be able to generate such a signature. This property will be referred to here as rescue of authorship. The main difference to the proposal of Rivest et al. (2001) is presented before we even begin signature generation. The values used as input to the trapdoor function are message authentication codes - MACs generated by the HMAC algorithm, an algorithm for message authentication based on hash function collision resistant. This simple modification will allow, in the future, the subscriber to reveal itself as the true author of the message by showing the secret values to generate those MACs.

As camadas de enlace empregadas em redes sem fio de baixo custo e desempenho limitado, como as redes de sensores sem fio, são implementadas segundo o padrão IEEE 802.15.4. Prever o desempenho deste padrão é importante para analisar a viabilidade e o desempenho esperado de projetos envolvendo esse tipo de rede. Constatou-se que trabalhos anteriores com esse objetivo são incompletos no tocante às métricas aferidas e tem foco no cálculo de probabilidades, o que não faz parte da especificação do padrão. Assim, o objetivo deste trabalho foi projetar e implementar um modelo comportamental do padrão IEEE 802.15.4, cujos parâmetros possam ser facilmente alterados e que seja capaz de aferir as principais métricas de uma rede: vazão, taxa de entrega, atraso e gasto de energia. Os objetivos foram cumpridos com a validação do modelo perante simulação com o NS2. Além disso, o modelo foi utilizado para estudar a variação dos parâmetros aMaxFrameRetries, macMaxCSMABackos, initialCW e aUnitBackoPeriod do padrão IEEE 802.15.4, para estudar cenários em que os nós possuem tráfego assimétrico e cenários com diferentes relações de tamanho e taxa de chegada de pacotes, mantendo a taxa de bits constante. / Low cost and performance constrained wireless networks, such as wireless sensor networks, employ IEEE 802.15.4 standard as its MAC layer. Foreseeing this standard\'s performance is essential to analyze the feasibility and expected metrics results of these networks projects. It was observed that previous works with that aim are both incomplete regarding metrics of interest and focus on probability calculation, which is not part of the standard specication. Thus, the objective of this work is to project and implement a behavioral IEEE 802.15.4 standard model, which parameters may be easily set and that covers the main metrics of interest: throughput, delivery rate, delay and energy. The objectives were achieved, with model validation against NS2 simulations. Furthermore, the model was employed to analyze the performance variation caused by the parameters aMaxFrameRetries, macMaxCSMABackos, initialCW and aUnitBackoPeriod from the IEEE 802.15.4 standard and also scenarios with asymmetric trac conditions and packet size and arrival rate variations, maintaining a constant bitrate.

Pendant les dernières années, le réseau cellulaire est devenu accessible presque partout. Pour compléter ce réseau cellulaire terrestre, plusieurs systèmes basés sur des satellites à basse orbite (LEO Low Earth Orbit) et moyenne orbite (MEO Medium Earth Orbit) ont été développés pour offrir une couverture globale. Les services multimédias sont largement demandés sur une échelle globale.<br />Notre but est de développer une couche d'accès MAC au canal satellitaire tout en respectant les contraintes de la constellation LEO. Un grand nombre d'utilisateurs de différents types vont essayer d'accéder au canal satellite (sens montant) afin d'envoyer leurs paquets. Il faut distribuer les ressources disponibles entre les différents utilisateurs de façon à respecter la QoS de chaque utilisateur et à minimiser le gaspillage. Nous avons traité dans cette thèse les ponts suivants :<br />·Nous avons adopté les techniques CDMA (Code Division Multiple Access) et TDMA (Time Division Multiple Access) pour définir les protocoles d'accès proposés en système LEOS. Ces techniques sont adaptées afin d'être utilisées d'une manière efficace dans le cas spécifique de satellites LEO (long RTD (Round Trip Delay), Handover, ).<br />·Nous avons utilisé un contrôle d'admission pour les différents types de services qui agit au niveau d'appel afin d'accepter un maximum d'utilisateurs de différents types tout en respectant la QoS de chacun. Ce contrôle utilise une fonction à capacité équivalente adaptée aux différents contextes de nos études.<br />·Nous avons défini des services au niveau MAC d'une façon générique. Les services sont supportés au niveau MAC par des MTCs (MAC Transfer Capabilities) afin de garantir la QoS demandée par chaque service. Nous avons proposé des MTCs qui supportent tous les services et applications possibles.<br />·Nous avons étudié le système pour des utilisateurs hétérogènes ce qui rend l'intégration de services nécessaire. La comparaison dépend de l'intégration et de la QoS de chaque utilisateur. Le but est toujours de maximiser la capacité totale du système.<br />·Nous avons étudié le multiplexage de services et l'allocation de ressources pour les différents protocoles d'accès. Des techniques d'ordonnancement et de partage de ressources sont proposées afin d'atteindre pour un protocole d'accès donné la performance maximale.<br />L'intégration de satellite avec l'UMTS et l'utilisation de l'ATM au sein du réseau de cur sont deux facteurs essentiels qui dirigent nos propositions sur la couche MAC. Les services vus par cette couche sont appelés les MTCs (MAC Transfer Capabilities) et doivent se coordonner avec les services de l'UMTS et l'ATM. Le choix est basé aussi sur les sources de trafics utilisées dans les différents chapitres.

More and more embedded systems choose ARM-based micro-controllers as CPU. If no embedded OS built with the system, the application scope will be restricted. Therefore, the need of embedded OS is vital. There are many embedded OS¡¦s in the market, but the embedded Linux has many advantages and is widely accepted. Commercial embedded Linux takes less refund than other embedded OS¡¦s. The kernel and most applications are distributed in GPL open source copyright, and is highly portable to many machine platforms. Presently, the hardware key-technology is highly skilled. The margin of 3C industrial has gone down rapidly. Therefore, people focus on adapting integrated technology to practicality and innovation to make cost down. Developers choose appropriate ARM micro-controllers according to demanding functionality of their products. The microcontroller is not necessary running with Linux distribution. Two approaches can be used to resolve the embedded OS issue. The first approach is porting Linux to the platform without any refund. The second approach is to pay for commercial Linux. Embedded system peripheral devices aim at powerful functionalities and economy. For instance, UART interface is cheap and low data transfer rate. The target board communicates with host via RS-232. RS-232 acts as serial console to play dumb terminal under Linux. Industrial applications often make use of RS-xxx for UART physical transmission layer. For instance, RS-485 applies modbus protocol to build cheap monitor systems. Network transmission is a necessary function, and it generally achieves high data transfer rate application through Ethernet. The UNIX-like network socket has served network application very well. Embedded systems are usually diskless systems. In order to keep permanent data, using flash memory as block disk system is a widely adapted strategy and which operates flash memory through MTD subsystems¡][28]¡^. An MTD subsystem contains two different modules, ¡§user¡¨and ¡§driver¡¨. In the driver module, CFI¡][40]¡^ is applied to probe flash chip, partition it and provide operating function. Flash translation layer and file-system are applied in the user module. MTD BLOCK is used to emulate the flash partitions as block devices which are then mounted into Linux virtual file system¡]VFS¡^with JFFS2 type, designed according to the feature of flash devices. In this thesis, we will describe in detail the procedure of porting Linux to ARM micro-controllers. The motivation of the work is introduced in chapter 1. In chapter 2, we introduce development tools and the main flow of the porting procedure. In chapter 3, we describe the LH79525 platform and the main perepherals on the target board, then introduce the ARM programmer model. In chapter 4, we examine the required knowledge and the important issues for porting ARM Linux. In chapter 5, we describe the details of porting Linux to run with Sharp LH79525, including modifying the key source codes and adjusting kernel configuration for embedding the UART, ethernet MAC, and MTD subsystem. In chapter 6, we do step-by-step validation and apply an integrated application with the LF-314CP temperature controller¡][46]¡^ by law-chain technology for the LH79525 target board running with the ported ARM Linux. In chapter 7, we present some issues for future work and improvement, then make a conclusion for the thesis.

<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>