Efficient address auto-configutation in ad hoc networks - protocol & algorithms

Mobile Ad hoc NETworks (MANETs) are an important part of mobile communications as they allow communications without the presence of an infrastructure. A MANET consists of an autonomous system of mobile devices. In contrast with infrastructure networks, MANET nodes act as hosts as well as routers. In the Internet, multi-hop communications are supported by the network layer, i.e. the Internet Protocol (IP). However, this requires the availability of a unique IP address. Due to the dynamic and decentralized nature of MANETs, and especially due to the mobility of nodes, providing and maintaining this unique IP address automatically in a decentralized way is a challenge addressed by auto-configuration protocols as part of the network layer. Several protocols to support this in fully decentralized environments as present in MANETs have been developed, e.g., the MANETConf, Buddy and Prophet protocols. However, they fail to solve the problem efficiently in scenarios where the nodes are highly mobile, e.g., as is the case with typical car-to-car applications. This thesis presents an address auto-configuration protocol that efficiently supports highly dynamic mobile ad hoc networks. This protocol, the Logical Hierarchical Addressing (LHA) protocol, focuses on the fast assigning of IP addresses to new nodes joining a MANET while minimizing the signaling overhead. Besides this, LHA introduces a solution for the merging problem ensuring, the uniqueness of IP addresses in the network when two previously independent MANETs merge. LHA is based on the idea that the address assignments can be achieved locally by the neigh-boring nodes of a requester, which in turn leads to a fast address assignment. Basically, in LHA, each configured node in a MANET is able to select, allocate and assign a unique address to a new node requesting an address that is free. By dividing the address space logically among configured nodes LHA is able to build a number of hierarchical structures of IP addresses. By this means, LHA solves efficiently the merging problem. Furthermore, the utilization of a certain assignment algorithm and specific address data structures is the key that LHA is able to solve the problem of missing IP addresses due to the departure of nodes. Because LHA is less dependent on unicast connections it reduces the signaling overhead and achieves fast address assignment. This in turn makes LHA highly suitable to the use in a wide range of scenarios, especially in those which are high mobility.Mobile Ad-Hoc-Netzwerke (MANETs) sind ein bedeutender Teil der Mobilkommunikation, da sie Kommunikation ohne das Vorhandensein von Infrastruktur erlauben. Ein MANET besteht aus einem autonomen System von mobilen Geräten. Im Gegensatz zu Infrastruktur-Netzwerken agieren MANET-Knoten als Host, ebenso wie als Router. Im Internet werden Multi-Hop-Kommunikationen durch den Netzwerk-Layer unterstützt, z.B. das Internet Protokoll (IP). Dies verlangt jedoch die Verfügbarkeit einer eindeutigen IP-Adresse. Wegen der dynamischen und dezentralen Natur von MANETs und besonders wegen der Mobilität der Knoten, ist die automatische, dezentrale Bereitstellung und Verwaltung dieser eindeutigen IP-Adresse eine Herausforderung, die durch Autokonfigurationsprotokolle als Teil des Netzwerk-Layers gelöst werden soll. Zur Unterstützung dieser dezentralen Umgebung, die durch MANET repräsentiert werden, wurden verschiedene Protokolle entwickelt, wie MANETConf, Buddy und Prophet. Allerdings verfehlen sie eine effiziente Lösung des Problems in Szenarien mit hoch-mobilen Knoten, wie z.B. bei typischen "Auto-zu-Auto"-Anwendungen. Die vorgestellte Arbeit präsentiert ein Adressenautokonfigurationsprotokoll, das hoch dynamische mobile Ad-Hoc-Netzwerke unterstützt. Dieses Protokoll, genannt "Logical Hierarchical Addressing (LHA)", konzentriert sich auf die schnelle Zuweisung von IP-Adressen für neue Knoten, die einem MANET beitreten, und minimiert gleichzeitig den Signal-Overhead. Zusätzlich stellt LHA eine Lösung zum Vereinigungsproblem von Netzwerken vor und sichert die Eindeutigkeit von IP-Adressen, wenn sich 2 vorher unabhängige MANETs vereinigen. LHA basiert auf der Idee, dass die Adresszuweisung lokal durch jeden benachbarten Knoten eines anfragenden Knotens durchgeführt werden kann, was zusätzlich zu einer schnelleren Adresszuweisung führt. In LHA kann jeder konfigurierte Knoten in einem MANET für einen neuen Knoten eine eindeutige, freie Adresse auswählen und zuweisen. Durch die logische Aufteilung des Adressbereiches zwischen den konfigurierten Knoten kann LHA eine Anzahl hierarchischer Strukturen von IP-Adressen aufbauen, wodurch LHA das Vereinigungsproblem effektiv löst. Des Weiteren ist der Einsatz eines speziellen Zuweisungsalgorithmus und spezieller Adressdatenstrukturen der Schlüssel dafür, das LHA das Problem der durch das Verschwinden von Knoten fehlenden IP-Adressen lösen kann. Da LHA weniger abhängig von Unicast-Verbindungen ist, reduziert es den Signal-Overhead und erreicht eine schnelle Adresszuweisung. Dieser Effekt bewirkt die hohe Eignung von LHA für eine Vielzahl von Szenarien, insbesondere hoch mobile Umgebungen

Message Complexity Analysis of Mobile Ad Hoc Network (Manet) Address Autoconfiguration Protocols

This dissertation proposes a novel method to perform a quantitative analysis of message complexity and applies this method in comparing the message complexity among the mobile ad hoc network (MANET) address autoconfiguration protocols. The original publications on the address autoconfiguration protocols had many incomplete parts making them insufficient to use on practical MANETs. Therefore, the first objective of the executed research was to complete the address autoconfiguration protocols by filling in all the missing gaps to make them operational. The missing procedures that were filled in have been developed based on the most logical procedures being faithful to the original protocol publications. In this dissertation, to obtain the upper bound of the message complexity of the protocols, the O-notation of a MANET group of N nodes has been applied. To asymptotically calculate the total number of messages generated by a protocol's step or procedure, an investigation on the nodes broadcasting, unicasting, relaying, and receiving messages is conducted and used in obtaining the upper bound of the message complexity for each protocol.School of Electrical & Computer Engineerin

PAN: Providing Reliable Storage in Mobile Ad Hoc Networks with Probabilistic Quorum Systems

Reliable storage of data with concurrent read/write accesses (or query/update) is an ever recurring issue in distributed settings. In mobile ad hoc networks, the problem becomes even more challenging due to highly dynamic and unpredictable topology changes. It is precisely this unpredictability that makes probabilistic protocols very appealing for such environments. Inspired by the principles of probabilistic quorum systems, we present a Probabilistic quorum system for Ad hoc Networks (PAN), a collection of protocols for the reliable storage of data in mobile ad hoc networks. Our system behaves in a predictable way due to the gossip-based diffusion mechanism applied for quorum accesses, and the protocol overhead is reduced by adopting an asymmetric quorum construction. We present an analysis of our PAN system, in terms of both reliability and overhead, which can be used to fine tune protocol parameters to obtain the desired tradeoff between efficiency and fault tolerance. We confirm the predictability and tunability of PAN through simulations with ns-2

Service and auto-configuration framework for secure Ad-hoc environments in Android and Linux

Dissertação de mestrado em Engenharia de InformáticaAd-hoc networks can be useful in many contexts because they can be spontaneously created and do not require any sort of infrastructure. They can be useful for small groups when no other network is accessible. They can also be used in wider areas as a low cost replacement for wireless infrastructure networks with multiple dedicated access points. Despite this, ad-hoc networks are not a very popular option for most users. Unfortunately, ad-hoc networks are not as user friendly as infrastructure networks. The latter ones usually provide standardized mechanisms that perform the essential configurations for the correct functioning of the network. Ad-hoc networks do not have standardized mechanisms adapted to them. Each wireless network manager supports a different set of configuration mechanisms. There is usually no problem when every machine uses the same operating system but when different ones are used, users may need to manually perform the required configurations. Another cause for this low popularity is the lack of useful and easy to use applications. These applications are usually hosted on the Internet, as it provides a larger variety of business models. To tackle these problems, new forms of automatically configuring machines and providing services should be explored. These services must be easy to develop, in order to attract the developers that would develop them. The designed solutions must also be adapted to ad-hoc environments. Another important aspect that must be addressed is security. In some contexts, such as public and corporate environments, security can be essential to provide authentication and even to allow the correct functioning of the network.As redes ad-hoc podem ser uteis em muitos contextos visto poderem ser criadas espontaneamente e não necessitarem de qualquer tipo de infraestrutura. Elas podem ser uteis para grupos pequenos quando nenhuma outra rede pode ser acedida. Tamb em podem ser usadas em areas amplas como uma alternativa de baixo custo para redes sem os infraestruturadas com vários pontos de acesso dedicados. Ainda assim, as redes ad-hoc não são uma opção muito popular para a maioria dos utilizadores. Infelizmente, as redes ad-hoc não são tão simples de utilizar como as redes de infraestrutura. Estas ultimas normalmente utilizam mecanismos standardizados para efectuar as configurações que são essenciais para o correcto funcionamento da rede. As redes ad-hoc não têm mecanismos standardizados adaptados a elas. Cada aplicação gestora de redes sem os suporta um conjunto diferente de mecanismos de confi guração. Normalmente não há problemas quando todas as máquinas usam o mesmo sistema operativo mas quando são usados diversos, os utilizadores podem ter que con- figurar manualmente as máquinas. Outra causa para esta baixa popularidade e a falta de aplicações uteis e de fácil utilização. Estas aplicações são normalmente utilizadas na Internet, visto que esta fornece uma maior variedade de modelos de negócio. Para abordar estes problemas, novas formas de configurar máquinas automaticamente e de fornecer serviços devem ser exploradas. Estes serviços devem ser fáceis de desenvolver, de forma a atrair os developers que os irão desenvolver. As solu ções desenhadas também devem estar adaptadas a ambientes ad-hoc. Outro aspecto importante que tem de ser focado e a segurança. Em alguns contextos, tais como ambientes públicos e empresariais, a segurança pode ser essencial para fornecer autenticação e mesmo permitir o correcto funcionamento da rede. Neste trabalho, uma framework funcional que trata estes problemas e desenhada e implementada. A framework e capaz de efectuar automaticamente as configurações necessárias a criação de um ambiente ad-hoc funcional e seguro. E também capaz de fornecer serviços especializados e de fácil desenvolvimento, sobre o ambiente seguro criado de forma espontânea. A framework desenvolvida e fácil de utilizar e foi exaustivamente testada em Android e Linux, embora possa ser facilmente estendida de forma a funcionar em muitos outros sistemas operativos

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

Architectural and mobility management designs in internet-based infrastructure wireless mesh networks

Wireless mesh networks (WMNs) have recently emerged to be a cost-effective solution to support large-scale wireless Internet access. They have numerous ap- plications, such as broadband Internet access, building automation, and intelligent transportation systems. One research challenge for Internet-based WMNs is to design efficient mobility management techniques for mobile users to achieve seamless roam- ing. Mobility management includes handoff management and location management. The objective of this research is to design new handoff and location management techniques for Internet-based infrastructure WMNs. Handoff management enables a wireless network to maintain active connections as mobile users move into new service areas. Previous solutions on handoff manage- ment in infrastructure WMNs mainly focus on intra-gateway mobility. New handoff issues involved in inter-gateway mobility in WMNs have not been properly addressed. Hence, a new architectural design is proposed to facilitate inter-gateway handoff man- agement in infrastructure WMNs. The proposed architecture is designed to specifi- cally address the special handoff design challenges in Internet-based WMNs. It can facilitate parallel executions of handoffs from multiple layers, in conjunction with a data caching mechanism which guarantees minimum packet loss during handoffs. Based on the proposed architecture, a Quality of Service (QoS) handoff mechanism is also proposed to achieve QoS requirements for both handoff and existing traffic before and after handoffs in the inter-gateway WMN environment. Location management in wireless networks serves the purpose of tracking mobile users and locating them prior to establishing new communications. Existing location management solutions proposed for single-hop wireless networks cannot be directly applied to Internet-based WMNs. Hence, a dynamic location management framework in Internet-based WMNs is proposed that can guarantee the location management performance and also minimize the protocol overhead. In addition, a novel resilient location area design in Internet-based WMNs is also proposed. The formation of the location areas can adapt to the changes of both paging load and service load so that the tradeoff between paging overhead and mobile device power consumption can be balanced, and at the same time, the required QoS performance of existing traffic is maintained. Therefore, together with the proposed handoff management design, efficient mobility management can be realized in Internet-based infrastructure WMNs

Mobilidade de comunicações entre veículos e infraestrutura

Mestrado em Engenharia Electrónica e TelecomunicaçõesThe unique characteristics of VANETs, such as high mobility, dynamic topology and frequent loss of connectivity, turn the network selection scheme into a complex problem. In a crowded wireless environment that surrounds us, mainly in urban areas, there is a proliferation and superposition of multiple networks and technologies. Therefore, in order to guarantee connectivity in a transparent way for users, the presence of a connection manager capable of taking informed decisions is crutial. With the increase of mobile traffic, several initiatives have been performed for deploying free/low-cost Wi-Fi hotspots across the cities, in order to offload traffic from the cellular networks into more cost-effective networks. On the one hand, clients benefit from lower data prices, and on the other hand, operators may reduce the amount of cellular infrastructure deployed. Furthermore, users will certainly prefer to connect to a free source of Internet whenever it is available instead of paying for it. Since nodes in VANETs are vehicles, the perception of the surrounding networks is constantly changing, becoming unstable with speed. Therefore, the high mobility of nodes in VANETs jeopardizes the existing network selection mechanisms, which for the network election, are based on Received Signal Strength (RSS) to choose where to connect. Moreover, in a VANET environment, there are no mechanisms capable of taking into account V2V communication according to the WAVE/DSRC technology. Thereby, we propose a connection manager which considers the Wi-Fi networks, cellular networks and the WAVE/DSRC technology to provide connectivity to vehicles. This connection manager is capable of looking into relevant data that is available in VANET-equipped vehicles, increasing the dynamic of the decision process. VCM is a connection manager optimized to operate in VANET scenarios, which takes into account the vehicle speed and heading, the infrastructure position along with their availability and also the number of hops to reach the service provider, besides the link quality. The proposed connection manager is based on an Analytical Hierarchic Process (AHP) that combines several candidate networks, geographic inputs and physical factors to determine the best connection at all times, including the technology and the best network, for each user. To determine the priority of each parameter, we proposed the combination of pairwise comparisons between the criteria involved, according to Saaty's pairwise comparison scale, enhancing the process through simulation and using a Genetic Algorithm (GA). To observe the enhancements provided by VCM, two typical connection managers were implemented: BCM which only looks to the signal quality to choose where to connect, and PCM which takes into account users preference besides the RSS. The evaluation was performed in a Manhattan grid, composed by several vehicles using SUMO's car-following model and with equal turn probabilities, and infrastructure randomly spread across the scenario. The results show that VCM outperforms the other two connection managers, proving that it is capable of operating in general scenarios minimizing the packet loss and with a reduced number of performed handovers.As características únicas das redes veiculares, como a elevada mobilidade, a topologia dinâmica e a frequente perda de conectividade, tornam o esquema da escolha de rede num problema complexo. Num ambiente replecto de redes sem fios, principalmente nas áreas urbanas, existe um aglomerado e sobreposição de varias redes e tecnologias. Assim, para garantir ao utilizador a conectividade de forma transparente, é necessário a presença de um mecanismo capaz de tomar decisões informadas. Com o aumento do trafego móvel, varias iniciativas estão a ser realizadas, disponibilizando hotspots IEEE 802.11 a/g/n (Wi-Fi) pelas cidades, de forma a retirar trafego das redes celulares. Por um lado, os clientes podem usufruir de preços mais baixos e por outro lado, os operadores conseguem reduzir a quantidade de trafego móvel. Alem disso, os utilizadores irão preferir ligar-se a uma rede mais barata/grátis sempre que estiver disponível, desde que tenha boa qualidade. Uma vez que nas redes veiculares os nos são veículos, as redes disponíveis estão sempre a mudar, tornando-se cada vez mais instáveis com o aumento da velocidade. Assim, a mobilidade dos nos põe em causa as soluções existentes para mecanismos de selecção de redes, que maioritariamente para elegerem a melhor rede se baseiam apenas na qualidade do sinal. Alem disso, para um ambiente de redes veiculares, não existem mecanismos de selecção capazes de ter em conta comunicação Vehicle-to-Vehicle (V2V) de acordo com a tecnologia Wireless Access in Vehicular Environments (WAVE) / (Dedicated Short-Range Communications (DSRC). Assim, é proposta a criação de um gestor de conectividade capaz de ter em conta determinados factores que se encontram disponíveis nos veículos Vehicular Ad-hoc NETwork (VANET)-equipados para aumentar a dinâmica do processo de seleccao. O Vanet Connection Manager (VCM) é um gestor de conectividade optimizado para ambientes veiculares, que considera a disponibilidade de redes Wi-Fi, redes celulares e a tecnologia WAVE / DSRC para veículos. Este gestor tem em conta a velocidade e direcção do veículo, a posição das infraestructuras bem como a sua disponibilidade, o numero de saltos ate ao destino, alem da qualidade do sinal. O mecanismo proposto e baseado num Processo Analítico Hierárquico que combina varias redes candidatas, parâmetros geográficos e factores físicos para determinar a melhor ligação possível, incluindo a tecnologia e a melhor rede, para cada utilizador. Para o calculo das prioridades de cada parâmetro, foi proposto o método das combinações emparelhadas desenvolvido por Saaty, optimizando o processo através de simulação e recorrendo a um Algoritmo Genético. Para observar o desempenho do gestor de conectividade, implementaram-se dois gestores típicos de conectividade: Basic Connection Manager (BCM) que apenas tem em conta a força de sinal para escolher o melhor candidato, e o Preference-based Connection Manager (PCM) que tem em conta as preferências dos utilizadores para além da força de sinal. A avaliação foi realizada num cenário Manhattan, composto por vários veículos com modelos de simulação importados do SUMO e infraestrutura aleatoriamente colocada ao longo do cenário. Os resultados mostram que o VCM apresenta melhores resultados que os outros dois gestores de rede, provando que e capaz de operar em qualquer cenário, minimizando as perdas de dados e com um reduzido numero de mudanças de rede

Advanced Transport Protocols for Wireless and Mobile Ad Hoc Networks

This thesis comprises transport protocols in the following different areas of research: Fast Handover allows mobile IP end-devices to roam between wireless access routers without interruptions while communicating to devices in an infrastructure (e.g., in the Internet). This work optimizes the Fast Handover algorithm and evaluates the performance of the transport protocols UDP and TCP during fast handovers via measurements. The following part of the thesis focuses on vehicular ad hoc networks. The thesis designs and evaluates through simulations a point-to-point transport protocol for vehicular ad hoc networks and an algorithm to facilitate the reliable and efficient distribution of information in a geographically scoped target area. Finally, the thesis evaluates the impact of wireless radio fluctuations on the performance of an Ad Hoc Network. Measurements quantify the wireless radio fluctuations. Based on these results, the thesis develops a simple but realistic radio model that evaluates by means of simulations the impact on the performance of an ad hoc network. As a result, the work provides guidelines for future ad hoc protocol design