From MANET to people-centric networking: Milestones and open research challenges

In this paper, we discuss the state of the art of (mobile) multi-hop ad hoc networking with the aim to present the current status of the research activities and identify the consolidated research areas, with limited research opportunities, and the hot and emerging research areas for which further research is required. We start by briefly discussing the MANET paradigm, and why the research on MANET protocols is now a cold research topic. Then we analyze the active research areas. Specifically, after discussing the wireless-network technologies, we analyze four successful ad hoc networking paradigms, mesh networks, opportunistic networks, vehicular networks, and sensor networks that emerged from the MANET world. We also present an emerging research direction in the multi-hop ad hoc networking field: people centric networking, triggered by the increasing penetration of the smartphones in everyday life, which is generating a people-centric revolution in computing and communications

Flexible Application-Layer Multicast in Heterogeneous Networks

This work develops a set of peer-to-peer-based protocols and extensions in order to provide Internet-wide group communication. The focus is put to the question how different access technologies can be integrated in order to face the growing traffic load problem. Thereby, protocols are developed that allow autonomous adaptation to the current network situation on the one hand and the integration of WiFi domains where applicable on the other hand

Soluções de broadcast para redes 4G

Mestrado em Engenharia Electrónica e de TelecomunicaçõesA primeira difusão de conteúdos video e audio teve um forte impacto no quotidiano da população que assistiu a uma revolução nos modelos de transmissão de informação e de entretenimento. A evolução desde então foi significativa, e já na era digital, encontramo-nos face a uma nova sub-elevação da metodologia e do conceito subjacentes à transmissão de conteudos multimédia. O mundo actual apresenta, contudo, diferentes requisitos, de entre os quais se destacam a procura pela alta definição e mobilidade. A mobilidade tem sido um particular foco de atenção por parte dos operadores que exploram agora modelos para entregar uma vasta gama de serviços que sejam atractivos para os utilizadores. Esta dissertação apresenta um sumário das tecnologias emergentes de broadcast que se distinguem nas várias partes do mundo com a sua particular incidência geográfica, características e cenários de aplicação. É ainda apresentada uma arquitectura 4G abordando assuntos inerentes à mobilidade e qualidade de serviço com particular incidência nos aspectos relacionados com a integração de uma tecnologia de broadcast particular. Para avaliação da arquitectura proposta foram efectuados estudos com base num equipamento de broadcast na sua versão comercial, permitindo desta forma obter uma análise que ilustra o que os operadores podem esperar do estado actual dos dispositivos. Os resultados permitiram retirar ilações sobre o comportamento de um equipamento considerado como um produto final a disponibilizar aos operadores, quando integrado num ambiente 4G com suporte de mobilidade e QoS. Nomeadamente é discutida a sua aplicabildiade tendo em linha de conta as desvantagens introduzidas pelas características inerentes à própria tecnologia.Broadcast of video and audio through analogical television completely changed the paradigm of information and entertainment divulgation. Today, in the “digital era”, the Analogue Switch Off revolution is being held. Manufacturers and operators already show concerns regarding the support of mobility, quality of experience and of service. Delivering competitive High Definition contents and providing solutions for the average “on-the-move” user are two of the most important issues to be dealt by the service providers, which are also within the analysis scope of this work. This dissertation presents an overview on the most relevant broadcast technologies which are assumed to be of relative acceptance in their respective target market. It presents their main characteristics and applicability. 4G architectural concepts are also analyzed, closely dealing with mobility and quality of service provisioning, with particular focus on the seamless integration of broadcast technologies. As a mean to evaluate the feasibility of integrating broadcast technologies with 4G architectures, a performance evaluation study was performed using commercial equipment. In this way a several set of considerations constructed illustrating the features and functionalities which operators can expect or disregard from professional commercial broadcasting devices. Results allow the withdrawing of conclusions concerning the integration of a final broadcasting solution when incorporated within a 4G environment with QoS and mobility support. Its applicability is evaluated having in mind the performance drawbacks introduced by the specific technology, and generalized towards the gathering of more general conclusions which consider the main characteristics of the commercial broadcasting devices

Information-centric communication in mobile and wireless networks

Information-centric networking (ICN) is a new communication paradigm that has been proposed to cope with drawbacks of host-based communication protocols, namely scalability and security. In this thesis, we base our work on Named Data Networking (NDN), which is a popular ICN architecture, and investigate NDN in the context of wireless and mobile ad hoc networks. In a first part, we focus on NDN efficiency (and potential improvements) in wireless environments by investigating NDN in wireless one-hop communication, i.e., without any routing protocols. A basic requirement to initiate informationcentric communication is the knowledge of existing and available content names. Therefore, we develop three opportunistic content discovery algorithms and evaluate them in diverse scenarios for different node densities and content distributions. After content names are known, requesters can retrieve content opportunistically from any neighbor node that provides the content. However, in case of short contact times to content sources, content retrieval may be disrupted. Therefore, we develop a requester application that keeps meta information of disrupted content retrievals and enables resume operations when a new content source has been found. Besides message efficiency, we also evaluate power consumption of information-centric broadcast and unicast communication. Based on our findings, we develop two mechanisms to increase efficiency of information-centric wireless one-hop communication. The first approach called Dynamic Unicast (DU) avoids broadcast communication whenever possible since broadcast transmissions result in more duplicate Data transmissions, lower data rates and higher energy consumption on mobile nodes, which are not interested in overheard Data, compared to unicast communication. Hence, DU uses broadcast communication only until a content source has been found and then retrieves content directly via unicast from the same source. The second approach called RC-NDN targets efficiency of wireless broadcast communication by reducing the number of duplicate Data transmissions. In particular, RC-NDN is a Data encoding scheme for content sources that increases diversity in wireless broadcast transmissions such that multiple concurrent requesters can profit from each others’ (overheard) message transmissions. If requesters and content sources are not in one-hop distance to each other, requests need to be forwarded via multi-hop routing. Therefore, in a second part of this thesis, we investigate information-centric wireless multi-hop communication. First, we consider multi-hop broadcast communication in the context of rather static community networks. We introduce the concept of preferred forwarders, which relay Interest messages slightly faster than non-preferred forwarders to reduce redundant duplicate message transmissions. While this approach works well in static networks, the performance may degrade in mobile networks if preferred forwarders may regularly move away. Thus, to enable routing in mobile ad hoc networks, we extend DU for multi-hop communication. Compared to one-hop communication, multi-hop DU requires efficient path update mechanisms (since multi-hop paths may expire quickly) and new forwarding strategies to maintain NDN benefits (request aggregation and caching) such that only a few messages need to be transmitted over the entire end-to-end path even in case of multiple concurrent requesters. To perform quick retransmission in case of collisions or other transmission errors, we implement and evaluate retransmission timers from related work and compare them to CCNTimer, which is a new algorithm that enables shorter content retrieval times in information-centric wireless multi-hop communication. Yet, in case of intermittent connectivity between requesters and content sources, multi-hop routing protocols may not work because they require continuous end-to-end paths. Therefore, we present agent-based content retrieval (ACR) for delay-tolerant networks. In ACR, requester nodes can delegate content retrieval to mobile agent nodes, which move closer to content sources, can retrieve content and return it to requesters. Thus, ACR exploits the mobility of agent nodes to retrieve content from remote locations. To enable delay-tolerant communication via agents, retrieved content needs to be stored persistently such that requesters can verify its authenticity via original publisher signatures. To achieve this, we develop a persistent caching concept that maintains received popular content in repositories and deletes unpopular content if free space is required. Since our persistent caching concept can complement regular short-term caching in the content store, it can also be used for network caching to store popular delay-tolerant content at edge routers (to reduce network traffic and improve network performance) while real-time traffic can still be maintained and served from the content store

Routage et gestion de la mobilité dans les réseaux personnels

L'objectif de cette thèse est d'étudier des méthodes et des stratégies efficaces pour le routage et la gestion de la mobilité dans le cadre des réseaux personnels. Dans un premier temps, nous proposons le cadre de nos études: Personal Ubiquitous Environments (PUE). Un PUE est constitué d'un ensemble d'utilisateurs ayant des terminaux disposant d'interfaces réseau hétérogènes, et dont l'objectif est de mettre en oeuvre des mécanismes de coopération et de partage des ressources de manière totalement distribuée. Dans ce cadre, la thèse a proposé des solutions innovantes contribuant à améliorer la communication inter et intra réseau personnels. La première contribution porte sur le protocole PNRP (Personal Network Routing Protocol) dont le but est de développer un routage à base de politiques (policy-based routing) pour les environnements personnels. La seconde, intitulée ADD (Adaptive Distributed gateway Discovery), est un mécanisme totalement distribué pour la découverte de multiples chemins vers une passerelle vers un réseau opéré. De plus, étant donné que ces environnements sont hétérogènes par leurs compositions (réseaux d'accès, terminaux ...), une architecture de gestion de la mobilité qui permet une gestion unifiée de la localisation et de la mobilité sans coutures appliquant lénsemble des noeuds a également été traitée. Les résultats d'évaluation par simulation démontrent l'applicabilité et léfficacité des ces protocoles.The aim of this thesis is to investigate methods and strategies for efficient routing and mobility management in personal environments. The concept of Personal Ubiquitous Environments (PUE) is introduced which accommodates heterogeneous devices and access networks of different users and sustain the notion of sharing resources in a distributed manner. A prerequisite for achieving the resource (devices, networks) sharing in personal environments is the deployment of suitable communication protocols which establish efficient multi-hop routes betweens the devices of the PUE. Personal Network Routing Protocol (PNRP) has been developed to perform policy-based routing in personal environments. Moreover, in certain personal networking scenarios, the infrastructure network components (i.e. gateways) are more than one-hop distance from the user's devices; Adaptive Distributed gateway Discovery (ADD) protocol is thereby proposed to efficiently discover the multi-hop routes towards the gateway in a totally distributed manner. All the more, since the personal environments regroups heterogeneous access networks, an efficient mobility management architecture is proposed which offers unified location management and seamless handover experience to dynamic personal nodes. The proposed protocols are assessed by means of numerous communication scenarios; the simulation results demonstrate the applicability of the proposed protocols

Interaktive latenzkritische Anwendungen in mobilen Ad-hoc Netzen

In this thesis we discuss the challenges that latency-sensitive interactive applications face in mobile ad-hoc networks. By using multi-player games as an example, we argue that the traditional client-server architecture is unsuitable for this new environment. We consequently create a novel communication architecture as well as quality of service mechanisms that can support the network requirements of such applications in mobile environments. By using a number of distributed zone servers that are selected and managed dynamically by our server selection algorithm, we provide a scalable approach that offers the necessary redundancy. Furthermore, we propose additional quality of service mechanisms to reduce latency and packet loss for interactive applications. We evaluate our approach through network simulation and realistic mobile gaming scenarios. The performance of our evaluation is checked against real-world measurements.In dieser Arbeit werden die Probleme und Herausforderungen von latenz-kritischen interactiven Computeranwendungen in mobilen Ad-hoc Netzen untersucht. Am Beispiel von Mehrbenutzercomputerspielen zeigen wir, dass traditionelle Client-Server Architekturen für diese neuen Umgebungen ungeeignet sind. Im Rahmen dieser Arbeit wird daher eine neue Kommunikationsarchitektur sowie verschiedene Mechanismen zur Erhöhung der Dienstgüte vorgeschlagen. Mit Hilfe von Zonenserver, die durch den Serverauswahlalgorithmus ausgesucht und verwaltet werden zeigen wir einen Ansatz auf, der sowohl bezüglich der Netzgröße skalierbar ist als auch die notwendige Redundanz bereitstellt. Wir zeigen die Funktionalität und die Leistung unseres Ansatzes mit Hilfe von Netzsimulationen bei denen realistische Szenarien für mobiles Spielen simuliert werden. Der hierbei benutze Netzsimulator wurde dafür auf Basis von eigenen Messungen verbessert und für das jeweilige Szenario passend eingestellt

Performance evaluation of realistic scenarios for vehicular ad hoc networks with VanetMobiSim and NS2

Català: En els darrers anys, el considerable creixement del sector dels serveis mòbils arreu del món es certament el major fenòmen al camp de les telecomunicaciones. Les tecnologies inalàmbriques han conduït al desenvolupament de nous sistemes de comunicació y serveis multimèdia. Degut al constant creixement del mercat automobilístic juntament amb la creixent demanda de la seguretat viària ha nascut un nou concepte al camp de les comunicaciones: les xarxes entre vehicles (VANETs). A les VANETs, cada vehicle pot actuar com a router o node, establint connexions entre vehicles propers o amb infraestructura a la carretera. Les VANET estan rebent més atenció del govern i de la indústria automobilística degut a l'àmplia varietat d'aplicacions y serveis que poden oferir, tal com sistemes de seguretet viària assistència a la carretera i accès a Internet. No obstant, el disseny i l'implementació de VANETs és una àrea d'investigació àmplia i complexa tal i com podem percebre, sabent que durant els darrers anys la comunitat investigadora s'ha centrat en l'estudi d'aquestes xarxes. Bàsicament, el nostre projecte està dividit en dues parts principals: Primerament, hem dut a terme una recerca relacionada amb l'estat actual de les VANET avui en dia, amb l'objectiu d'identificar els generadors de moviment i els simuladors de xarxes més apropiats i recomenats a la literatura. En segon lloc, hem decidit utilitzar el VanetMobiSim [80], com a generador de moviment degut a la seva varietat de models de movilitat que es poden testejar, i el NS2 [63] com a simulador de xarxes per ser un dels més utilitzats per molts autors a més de la seva compatibilitat amb el VanetMobiSim. Amb l'ús d'aquestes eines, VanetMobiSim i NS2, hem dut a terme una avaluació profunda de les prestacions de les VANET en diversos escenaris reals, assignant valors diferents a paràmetres tals com el nombre de nodes, la velocitat i el model de propagació.Castellano: En los últimos años, el considerable crecimiento del sector de los servicios móviles alrededor del mundo es con certeza el mayor fenómeno en el campo de las telecomunicaciones. Las tecnologías inalámbricas han conducido al desarrollo de nuevos sistemas de comunicación y servicios multimedia. Debido al constante crecimiento del mercado automovilístico y la creciente demanda en seguridad vial ha nacido un nuevo concepto en el campo de las comunicaciones: las redes entre vehículos (VANETs). En ellas, cada vehículo actúa como router, estableciendo conexiones entre vehículos cercanos o con infraestructura en la carretera. Las VANET estan recibiendo más atención del gobierno y de la industria automovilística debido a la amplia variedad de aplicaciones y servicios que puede ofrecer, tales como sistemas de seguridad vial, asistencia en carretera y acceso a Internet. Sin embargo, el diseño e implementación de las VANET es un area de investigación amplia y compleja, tal y como podemos percibir, sabiendo que durante los últimos años la comunidad investigadora se ha centrado en el estudio de estas redes. Básicamente, nuestro proyecto está dividido en dos partes principales: Primeramente, hemos llevado a cabo una búsqueda relacionada con el estado de arte de las VANET hoy en día, con el objetivo de identificar los generadores de movimiento i los simuladores de redes más apropiados i recomendados en la literatura. En segundo lugar, hemos decidido utilizar el VanetMobiSim [80], como generador de movimiento debido a la alta variedad de modelos de mobilidad que que se pueden testear, y el NS2 [63] como simulador de redes por ser uno de los más utilizados per muchos autores además de su compatibilidad con el VanetMobiSim. Con el uso de estas herramientas, hemos llevado a cabo una evaluación profunda de las prestaciones de las VANET en varios escenarios reales, asignando valores diferentes a parámetros tales como el número de nodos, la velocidad y el modelo de propagación.English: Over recent years, the considerable mobile services sector growth around the world was certainly the major phenomenon in the telecommunications field. Wireless technology has led to the development of new communications systems and multimedia services. Due to the continued growth of the vehicular industry and the increasing demand of road safety, a new concept in the communications field was born: vehicular networks (VANETs). In VANETs, each vehicle could act as router or node, establishing connections among nearby vehicles or with roadside infrastructure. VANETs are receiving more attention from governments and car manufacturers due to the wide variety of applications and services they can provide such as road safety systems, car assistance and Internet acces. However, designing and implementing VANETs is a complex and wide area of research as we can notice, knowing that in the last years the research and development community has focused on the study of such networks. Basically, our project is divided in two main parts: Firstly, we made a state of art related to the actual state of VANETs nowadays in order to find the most appropiate and recommended mobility generator and network simulator reported in the literature. Secondly, we decided to use VanetMobiSim [80], as a mobility generator due to its variety mobility models that could be tested, and NS2 [63] as a network simulator for being one of the most used by many authors and also due to its compatibilty with VanetMobiSim. Using these tools, VanetMobiSim and NS2, we carried out a deep performance evaluation of VANETs in several realistic scenarios, giving different values to parameters such as the number of nodes, speed and the propagation model

SDN-based VANET routing: A comprehensive survey on architectures, protocols, analysis, and future challenges

As the automotive and telecommunication industries advance, more vehicles are becoming connected, leading to the realization of intelligent transportation systems (ITS). Vehicular ad-hoc network (VANET) supports various ITS services, including safety, convenience, and infotainment services for drivers and passengers. Generally, such services are realized through data sharing among vehicles and nearby infrastructures or vehicles over multi-hop data routing mechanisms. Vehicular data routing faces many challenges caused by vehicle dynamicity, intermittent connectivity, and diverse application requirements. Consequently, the software-defined networking (SDN) paradigm offers unique features such as programmability and flexibility to enhance vehicular network performance and management and meet the quality of services (QoS) requirements of various VANET services. Recently, VANET routing protocols have been improved using the multilevel knowledge and an up-to-date global view of traffic conditions offered by SDN technology. The primary objective of this study is to furnish comprehensive information regarding the current SDN-based VANET routing protocols, encompassing intricate details of their underlying mechanisms, forwarding algorithms, and architectural considerations. Each protocol will be thoroughly examined individually, elucidating its strengths, weaknesses, and proposed enhancements. Also, the software-defined vehicular network (SDVN) architectures are presented according to their operation modes and controlling degree. Then, the potential of SDN-based VANET is explored from the aspect of routing and the design requirements of routing protocols in SDVNs. SDVN routing algorithms are uniquely classified according to various criteria. In addition, a complete comparative analysis will be achieved to analyze the protocols regarding performance, optimization, and simulation results. Finally, the challenges and upcoming research directions for developing such protocols are widely stated here. By presenting such insights, this paper provides a comprehensive overview and inspires researchers to enhance existing protocols and explore novel solutions, thereby paving the way for innovation in this field

Data Storage and Dissemination in Pervasive Edge Computing Environments

Nowadays, smart mobile devices generate huge amounts of data in all sorts of gatherings. Much of that data has localized and ephemeral interest, but can be of great use if shared among co-located devices. However, mobile devices often experience poor connectivity, leading to availability issues if application storage and logic are fully delegated to a remote cloud infrastructure. In turn, the edge computing paradigm pushes computations and storage beyond the data center, closer to end-user devices where data is generated and consumed. Hence, enabling the execution of certain components of edge-enabled systems directly and cooperatively on edge devices. This thesis focuses on the design and evaluation of resilient and efficient data storage and dissemination solutions for pervasive edge computing environments, operating with or without access to the network infrastructure. In line with this dichotomy, our goal can be divided into two specific scenarios. The first one is related to the absence of network infrastructure and the provision of a transient data storage and dissemination system for networks of co-located mobile devices. The second one relates with the existence of network infrastructure access and the corresponding edge computing capabilities. First, the thesis presents time-aware reactive storage (TARS), a reactive data storage and dissemination model with intrinsic time-awareness, that exploits synergies between the storage substrate and the publish/subscribe paradigm, and allows queries within a specific time scope. Next, it describes in more detail: i) Thyme, a data storage and dis- semination system for wireless edge environments, implementing TARS; ii) Parsley, a flexible and resilient group-based distributed hash table with preemptive peer relocation and a dynamic data sharding mechanism; and iii) Thyme GardenBed, a framework for data storage and dissemination across multi-region edge networks, that makes use of both device-to-device and edge interactions. The developed solutions present low overheads, while providing adequate response times for interactive usage and low energy consumption, proving to be practical in a variety of situations. They also display good load balancing and fault tolerance properties.Resumo Hoje em dia, os dispositivos móveis inteligentes geram grandes quantidades de dados em todos os tipos de aglomerações de pessoas. Muitos desses dados têm interesse loca- lizado e efêmero, mas podem ser de grande utilidade se partilhados entre dispositivos co-localizados. No entanto, os dispositivos móveis muitas vezes experienciam fraca co- nectividade, levando a problemas de disponibilidade se o armazenamento e a lógica das aplicações forem totalmente delegados numa infraestrutura remota na nuvem. Por sua vez, o paradigma de computação na periferia da rede leva as computações e o armazena- mento para além dos centros de dados, para mais perto dos dispositivos dos utilizadores finais onde os dados são gerados e consumidos. Assim, permitindo a execução de certos componentes de sistemas direta e cooperativamente em dispositivos na periferia da rede. Esta tese foca-se no desenho e avaliação de soluções resilientes e eficientes para arma- zenamento e disseminação de dados em ambientes pervasivos de computação na periferia da rede, operando com ou sem acesso à infraestrutura de rede. Em linha com esta dico- tomia, o nosso objetivo pode ser dividido em dois cenários específicos. O primeiro está relacionado com a ausência de infraestrutura de rede e o fornecimento de um sistema efêmero de armazenamento e disseminação de dados para redes de dispositivos móveis co-localizados. O segundo diz respeito à existência de acesso à infraestrutura de rede e aos recursos de computação na periferia da rede correspondentes. Primeiramente, a tese apresenta armazenamento reativo ciente do tempo (ARCT), um modelo reativo de armazenamento e disseminação de dados com percepção intrínseca do tempo, que explora sinergias entre o substrato de armazenamento e o paradigma pu- blicação/subscrição, e permite consultas num escopo de tempo específico. De seguida, descreve em mais detalhe: i) Thyme, um sistema de armazenamento e disseminação de dados para ambientes sem fios na periferia da rede, que implementa ARCT; ii) Pars- ley, uma tabela de dispersão distribuída flexível e resiliente baseada em grupos, com realocação preventiva de nós e um mecanismo de particionamento dinâmico de dados; e iii) Thyme GardenBed, um sistema para armazenamento e disseminação de dados em redes multi-regionais na periferia da rede, que faz uso de interações entre dispositivos e com a periferia da rede. As soluções desenvolvidas apresentam baixos custos, proporcionando tempos de res- posta adequados para uso interativo e baixo consumo de energia, demonstrando serem práticas nas mais diversas situações. Estas soluções também exibem boas propriedades de balanceamento de carga e tolerância a faltas