隨著網路訊務流量的快速成長和無線網路技術日漸成熟，如何妥善的運用有限的網路資源是一個成功擁塞控制機制要面對的根本問題。TCP為現行網路上最廣為使用的傳輸層協定，並且有許多的不同版本被提出來改進其效能上的問題，例如TCP NewReno，TCP SACK 及TCP Vegas等。然而由於TCP傳送端並未具有網路內部狀態的資訊，如可用頻寬等，大部份的TCP擁塞控制機制僅能依賴封包遺失做為觸發擁塞控制的指標。許多研究指出在無線的環境下TCP無法有效使用有限的資源並且分辨封包遺失的原因，因而造成整體的效能不佳。本篇研究提出一個藉由路由器輔助的TCP擁塞控制協定－TCP Muzha，仰賴路由器提供調速資訊，以幫助傳送端能不依靠封包遺失進行傳輸速度控制，並可更快速的達到最佳的傳輸速度。本研究同時提出模糊化的多層級速率調整方法，藉由動態所獲得的細膩資訊做擁塞避免及因應無線環境下因路由改變或傳輸介質不穩所產生的不必要傳輸速度減低。最後我們在NS2模擬器上對所提出的協定做效能評估，實驗結果顯示本協定除了能有效的避免擁塞外，並能減少不必要的降速及重傳封包的次數。 / Communication networks have evolved tremendously in the past decades. TCP is the most dominant and deployed end-to-end transport protocol across Internet today and will continue to be in the foresee future. It has numerous enhancing versions for wired network such as TCP Reno, TCP NewReno and TCP Vegas to improve the drawbacks of initial version of TCP. As IEEE 802.11 wireless network technology gains popularity, TCP is very likely to be popular for existing applications so far. However due to unawareness of network conditions, regular TCP is not able to fully control the limited resources and distinguish packet loss from congestion loss and random loss. Based on such implicit assumption, many studies have shown this would results in serious performance degradation in wireless environment. In this paper, we proposed a new TCP congestion control mechanism by router-assisted approach which is inspired by the concept of each wireless node playing the roles of terminal and router simultaneously. Based on the information feedback from routers, sender is able to adjust the sending speed dynamically in order to avoid overshooting problem. We also proposed a multilevel date rate adjustment method to control the date rate more precisely. Finally we evaluate the performance of our approach by NS2 simulator. Our proposed protocol has 5~10% higher throughput than TCP NewReno and much less number of retransmission. The fairness requirement is also achieved while our proposed protocol coexists with other major TCP variants.

Dans un contexte de besoins croissants de moyens de communication pour augmenter la sécurité des vols et répondre aux attentes des compagnies et des passagers, le monde de l'aviation civile cherche de nouveaux systèmes de communication pouvant répondre à ces objectifs. Les systèmes de communication sol-bord existants, que ce soit les solutions par satellites en bande L (SATCOM, ...) ou les solutions cellulaires par liaison directe avec le sol (HF, VHF, ...), présentent des limites en terme de capacité, de couverture et de coût.La proposition avancée dans le cadre de cette thèse est d'utiliser les avions comme relais afin de propager les données jusqu'à une station sol. Ce système peut être vu comme un réseau ad hoc mobile dont les nœuds sont les avions civils en vol. Grâce à plusieurs sauts successifs au travers d'avions relais, chaque avion doit pouvoir joindre le sol sans être à portée directe d'une station. Le réseau ad hoc ainsi formé peut ensuite être utilisé pour différentes classes de communications : contrôle aérien, services pour les compagnies aériennes ou pour les passagers. Une telle solution permettrait d'améliorer la couverture des solutions cellulaires classiques en zone continentale. Elle est également applicable en zone océanique où les seuls moyens disponibles sont actuellement le satellite et la HF. On peut imaginer que les coûts de déploiement et de maintenance seraient relativement bas puisque l'infrastructure sol est limitée.Dans cette thèse, nous avons étudié la faisabilité puis les performances qui peuvent être attendues pour ce système de communication aéronautique innovant.

This work presents a novel Peer to Peer (P2P) framework for Session Initiation Protocol (SIP) on Mobile Ad Hoc Network (MANET). SIP is a client-server model of computing which can introduce a single point of failure problem. P2P SIP addresses this problem by using a distributed implementation based on a P2P paradigm. However, both the traditional SIP and P2P SIP architectures are not suitable for MANETs because they are initially designed for infrastructured networks whose most nodes are static. We focus on distributed P2P resource lookup mechanisms for SIP which can tolerate failures resulting from the node mobility. Our target application is SIP-based multimedia communication in a rapidly deployable disaster emergency network. To achieve our goal, we provide four contributions as follows. The first contribution is a novel P2P lookup architecture based on a concept of P2P overlay network called a Structured Mesh Overlay Network (SMON). This overlay network enables P2P applications to perform fast resource lookups in the MANET environment. SMON utilizes a cross layer design based on the Distributed Hashing Table (DHT) and has direct access to OLSR routing information. Its cross layer design allows optimizing the overlay network performance during the change of network topology. The second contribution is a distributed SIP architecture on MANET providing SIP user location discovery in a P2P manner which tolerates single-point and multiple-point of failures. Our approach extends the traditional SIP user location discovery by utilizing DHT in SMON to distribute SIP object identifiers over SMON. It offers a constant time on SIP user discovery which results in a fast call setup time between two MANET users. From simulation and experiment results, we find that SIPMON provides the lowest call setup delay when compared to the existing broadcast-based approaches. The third contribution is an extended SIPMON supporting several participating MANETs connected to Internet. This extension (SIPMON+) provides seamless mobility support allowing a SIP user to roam from an ad hoc network to an infrastructured network such as Internet without interrupting an ongoing session. We propose a novel OLSR Overlay Network (OON), a single overlay network containing MANET nodes and some nodes on the Internet. These nodes can communicate using the same OLSR routing protocol. Therefore, SIPMON can be automatically extended without modifying SIPMON internal operations. Through our test-bed experiments, we prove that SIPMON+ has better performance in terms of call setup delay and handoff delay than MANET for Network Mobility (MANEMO). The fourth contribution is a proof-of-concept and a prototype of P2P multimedia communication based on SIPMON+ for post disaster recovery missions. We evaluate our prototype and MANEMO-based approaches through experimentation in real disaster situations (Vehicle to Infrastructure scenarios). We found that our prototype outperforms MANEMO-based approaches in terms of call setup delay, packet loss, and deployment time.

Submitted by LIVIA FREITAS (livia.freitas@ufba.br) on 2016-01-22T19:54:13Z No. of bitstreams: 1 dissertacao.pdf: 1513187 bytes, checksum: 42a06a5bef9e5b11ab1253e8a4755c09 (MD5) / Approved for entry into archive by Uillis de Assis Santos (uillis.assis@ufba.br) on 2016-02-15T21:55:36Z (GMT) No. of bitstreams: 1 dissertacao.pdf: 1513187 bytes, checksum: 42a06a5bef9e5b11ab1253e8a4755c09 (MD5) / Made available in DSpace on 2016-02-15T21:55:36Z (GMT). No. of bitstreams: 1 dissertacao.pdf: 1513187 bytes, checksum: 42a06a5bef9e5b11ab1253e8a4755c09 (MD5) / O consenso e um problema fundamental em sistemas distribuídos que pode ser utilizado como diretiva básica para o desenvolvimento de aplicações distribuídas tolerantes a faltas. Informalmente, o consenso tem o objetivo de fazer com que todos os processos corretos do sistema decidam por um valor único proposto pelos mesmos. Redes móveis ad hoc (ou MANET) são redes dinâmicas constituídas por um conjunto de processos ou nos, onde o canal de comunicação existente entre eles é tipicamente sem fio. Exemplos destas redes são as redes de sensores e sistemas cooperativos compostos de robôs móveis. O FT-CUP é uma solução para o consenso tolerante a faltas em redes dinâmicas. Nestas redes, o conhecimento prévio dos participantes e uma hipótese muito forte a ser considerada. Por isso, ao contrário do consenso clássico, o FT-CUP não tem esse conhecimento como requisito. De fato, existem poucos trabalhos de consenso que sejam adequados ao contexto de redes dinâmicas. Além disso, poucos deles apresentam uma análise do desempenho dos protocolos propostos. Este trabalho tem como principal objetivo complementar os resultados teóricos alcançados ate então para a resolução do FT-CUP e analisar os aspectos práticos da sua realização em redes MANET. Para isso, são propostas implementações para os algoritmos necessários ao FT-CUP e realizadas simulações em cenários realistas. A partir dos resultados obtidos nos experimentos de simula coes, chegou-se a um conjunto de parâmetros para os quais e possível a convergência do FT-CUP, definindo-se então as características de uma rede onde o consenso pode ser resolvido de maneira aproximada. Determinou-se também o comportamento do protocolo a partir de diferentes variações de cenários e parâmetros usados nas execuções das simulações.

Peer-to-Peer (P2P) overlays were initially proposed for use with wired networks. However, the very rapid proliferation of wireless communication technology has prompted a need for adoption of P2P systems in mobile networks too. There are many common characteristics between P2P overlay networks and Mobile Ad-hoc Networks (MANET). Self-organization, decentralization, a dynamic nature and changing topology are the most commonly shared features. Furthermore, when used together, the two approaches complement each other. P2P overlays provide data storage/retrieval functionality and MANET provides wireless connectivity between clients without depending on any pre-existing infrastructure. P2P overlay networks can be deployed over MANET to address content discovery issues. However, previous research has shown that deploying P2P systems straight over MANET does not exhibit satisfactory performance. Bandwidth limitation, limited resources and node mobility are some of the key constraints. This thesis proposes a novel approach, OneHopOverlay4MANET, to exploit the synergies between MANET and P2P overlays through cross-layering. It combines Distributed Hash Table (DHT) based structured P2P overlays with MANET underlay routing protocols to achieve one logical hop between any pair of overlay nodes. OneHopOverlay4MANET constructs a cross-layer channel to permit direct exchange of routing information between the Application layer, where the overlay operates, and the MANET underlay layer. Consequently, underlay routing information can be shared and used by the overlay. Thus, OneHopOverlay4MANET reduces the typical management traffic when deploying traditional P2P systems over MANET. Moreover, as a result of building one hop overlay, OneHopOverlay4MANET can eliminate the mismatching issue between overlay and underlay and hence resolve key lookups in a short time, enhancing the performance of the overlay. v In this thesis, we present OneHopOverlay4MANET and evaluate its performance when combined with different underlay routing protocols. OneHopOverlay4MANET has been combined with two proactive underlays (OLSR and BATMAN) and with three reactive underlay routing protocols (DSR, AODV and DYMO). In addition, the performance of the proposed system over OLSR has been compared to two recent structured P2P over MANET systems (MA-SP2P and E-SP2P) that adopted OLSR as the routing protocol. The results show that better performance can be achieved using OneHopOverlay4MANET.

Acompanha anexo de ilustrações / Orientador: Jorge Coli / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias Humanas / Made available in DSpace on 2018-07-21T11:48:17Z (GMT). No. of bitstreams: 1 Alvim_PedrodeAndrade_M.pdf: 15600000 bytes, checksum: 2f6d6f815fc49b5f072ac053928a445d (MD5) Previous issue date: 1996 / Resumo: Não informado. / Abstract: Not informed. / Mestrado / Mestre em História

Mobile Ad hoc network routing protocols have been divided in several different categories such as Reactive and Proactive Routing Protocol. The performances of these categories are evaluated in different scenario with TCP variants. We present a comprehensive TCP performance evaluation study to understand the nature of the TCP performance in different scenarios with variable amount of payload and number of nodes. The traffic consists of three different packet sizes i.e. 512, 1000, 1500 bytes each. Three different routing protocols (AODV, DSR and TORA) are to be evaluated with three different TCP variants (Tahoe, Reno and New Reno) in three different scenarios having 3, 5 and 8 nodes. The performances parameters on the basis of which routing protocols are to be graded are mainly throughput, congestion window and delay. Conclusions are drawn based on the simulation results and the comparisons between them have been elaborated. / N.W.F.P PAKISTAN. Mobile no: 0092-3339173438

in English The aim of the study is to show Bataille's esthetic thoughts, dispersed in several Bataille's works, as a consistent theory of art. Through his fascination for cruel and evil, Bataille turns his interest to the matter and in revue called Documents he describes the appeal of low forms due to their proximity to formlessness. Beyond this frontier there is a sphere of "not-knowing", where the logical reason can not impenetrate. This sphere of excess is not only out of logical concept, but also out of our life, i. e. before our birth and after our death. In an organized society this sphere is forbidden. The tabu that guards it protects us from the destructive forces of chaos which could appear through the death rage, violent sexual passions, cruelty and evil. Human desire to see what is in this sphere comes from his nostalgia for a naturalness which had been lost when we changed from animals into human beings. The animal does not obey any rule and in ancient societies it used to represent the divinity. The lost intimity of present instant, as explained in Lascaux or Literature et le Mal, is mediated to us through religious transgression of law (sacrifice) or as fiction in art (transgression in modus "a like") or through destruction of academic forms. Such moments are always accompanied by...

This dissertation presents novel approaches to modeling and analyzing security and resource allocation in mobile ad hoc networks (MANETs). The research involves the design, implementation and simulation of different models resulting in resource sharing and security’s strengthening of the network among mobile devices. Because of the mobility, the network topology may change quickly and unpredictably over time. Moreover, data-information sent from a source to a designated destination node, which is not nearby, has to route its information with the need of intermediary mobile nodes. However, not all intermediary nodes in the network are willing to participate in data-packet transfer of other nodes. The unwillingness to participate in data forwarding is because a node is built on limited resources such as energy-power and data. Due to their limited resource, nodes may not want to participate in the overall network objectives by forwarding data-packets of others in fear of depleting their energy power. To enforce cooperation among autonomous nodes, we design, implement and simulate new incentive mechanisms that used game theoretic concepts to analyze and model the strategic interactions among rationale nodes with conflicting interests. Since there is no central authority and the network is decentralized, to address the concerns of mobility of selfish nodes in MANETs, a model of security and trust relationship was designed and implemented to improve the impact of investment into trust mechanisms. A series of simulations was carried out that showed the strengthening of security in a network with selfish and malicious nodes. Our research involves bargaining for resources in a highly dynamic ad-hoc network. The design of a new arbitration mechanism for MANETs utilizes the Dirichlet distribution for fairness in allocating resources. Then, we investigated the problem of collusion nodes in mobile ad-hoc networks with an arbitrator. We model the collusion by having a group of nodes disrupting the bargaining process by not cooperating with the arbitrator. Finally, we investigated the resource allocation for a system between agility and recovery using the concept of Markov decision process. Simulation results showed that the proposed solutions may be helpful to decision-makers when allocating resources between separated teams.

Recientes avances en las tecnologías de la comunicación, así como la proliferación de nuevos dispositivos de computación, están plasmando nuestro entorno hacia un Internet ubicuo. Internet ofrece una plataforma global para acceder con bajo coste a una vasta gama de servicios de telecomunicaciones, como el correo electrónico, comercio electrónico, tele-educación, tele-salud y tele-medicina a bajo coste. Sin embargo, incluso en los países más desarrollados, un gran número de áreas rurales todavía están pobremente equipadas con una infraestructura básica de telecomunicaciones. Hoy en día, existen algunos esfuerzos para resolver esta falta de infraestructura, pero resultan todavía insuficientes. Con este objetivo presentamos en esta tesis RuralNet, una red comunitaria inalámbrica para proveer acceso a Internet de forma personalizada a los subscriptores de un área rural. Los objetivos de este estudio han sido el desarrollo de una nueva arquitectura para ofrecer un acceso a Internet flexible y seguro para zonas rurales aisladas. RuralNet combina el paradigma de las redes mesh y el uso de los dispositivos inalámbricos embebidos más económicos para ofrecer un gran número de servicios y aplicaciones basados en Internet. La solución desarrollada por RuralNet es capaz de cubrir grandes áreas a bajo coste, y puede también ser fácilmente desplegado y extendido tanto en términos de cobertura como de servicios ofrecidos. Dado que la implementación y la evaluación de RuralNet requiere un alto coste y una gran cantidad de mano de obra, hemos considerado que la simulación y la emulación eran una alternativa válida para ahorrar costes. Con este objetivo hemos desarrollado Castadiva, un emulador flexible proyectado para la evaluación de redes MANET y mesh. Castadiva es un emulador basado en dispositivos de bajo coste, utilizado para evaluar los protocolos y las aplicaciones desarrolladas. / Hortelano Otero, J. (2011). Design and implementation of architectures for the deployment of secure community wireless networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/10079 / Palancia