Contact-Based Architecture for Resource Discovery (CARD) in Large Scale MANets

In this paper we propose a novel architecture, CARD, for resource discovery in large scale Mobile Ad hoc Networks (MANets) which, may scale up to thousands of nodes and may span wide geographical regions. Unlike previously proposed schemes, our architecture avoids expensive mechanisms such as global flooding as well as complex coordination between nodes to form a hierarchy. CARD is also independent of any external source of information such as GPS. In our architecture nodes within a limited number of hops from each node form the neighborhood of that node. Resources within the neighborhood can be readily accessed with the help of a proactive scheme within the neighborhood. For accessing resources beyond the neighborhood, each node also maintains a few distant nodes called contacts. Contacts help in creating a small world in the network and provide an efficient way to query for resources beyond the neighborhood. As the number of contacts of a node increases, the network view (reachability) of the node increases. Paths to contacts are validated periodically to adapt to mobility. We present mechanisms for contact selection and maintenance that attempt to increase reachability while minimizing overhead. Our simulation results show a clear trade-off between increase in reachability on one hand, and contact selection and maintenance overhead on the other. Our results suggest that CARD can be configured to provide a desirable reachability distribution for different network sizes. Comparisons with other schemes for resource discovery, such as flooding and bordercasting, show our architecture to be much more efficient and scalable.Comment: 10 pages, 15 figure

Resource-efficient strategies for mobile ad-hoc networking

The ubiquity and widespread availability of wireless mobile devices with ever increasing inter-connectivity (e. g. by means of Bluetooth, WiFi or UWB) have led to new and emerging next generation mobile communication paradigms, such as the Mobile Ad-hoc NETworks (MANETs). MANETs are differentiated from traditional mobile systems by their unique properties, e. g. unpredictable nodal location, unstable topology and multi-hop packet relay. The success of on-going research in communications involving MANETs has encouraged their applications in areas with stringent performance requirements such as the e-healthcare, e. g. to connect them with existing systems to deliver e-healthcare services anytime anywhere. However, given that the capacity of mobile devices is restricted by their resource constraints (e. g. computing power, energy supply and bandwidth), a fundamental challenge in MANETs is how to realize the crucial performance/Quality of Service (QoS) expectations of communications in a network of high dynamism without overusing the limited resources. A variety of networking technologies (e. g. routing, mobility estimation and connectivity prediction) have been developed to overcome the topological instability and unpredictability and to enable communications in MANETs with satisfactory performance or QoS. However, these technologies often feature a high consumption of power and/or bandwidth, which makes them unsuitable for resource constrained handheld or embedded mobile devices. In particular, existing strategies of routing and mobility characterization are shown to achieve fairly good performance but at the expense of excessive traffic overhead or energy consumption. For instance, existing hybrid routing protocols in dense MANETs are based in two-dimensional organizations that produce heavy proactive traffic. In sparse MANETs, existing packet delivery strategy often replicates too many copies of a packet for a QoS target. In addition, existing tools for measuring nodal mobility are based on either the GPS or GPS-free positioning systems, which incur intensive communications/computations that are costly for battery-powered terminals. There is a need to develop economical networking strategies (in terms of resource utilization) in delivering the desired performance/soft QoS targets. The main goal of this project is to develop new networking strategies (in particular, for routing and mobility characterization) that are efficient in terms of resource consumptions while being effective in realizing performance expectations for communication services (e. g. in the scenario of e-healthcare emergency) with critical QoS requirements in resource-constrained MANETs. The main contributions of the thesis are threefold: (1) In order to tackle the inefficient bandwidth utilization of hybrid service/routing discovery in dense MANETs, a novel "track-based" scheme is developed. The scheme deploys a one-dimensional track-like structure for hybrid routing and service discovery. In comparison with existing hybrid routing/service discovery protocols that are based on two-dimensional structures, the track-based scheme is more efficient in terms of traffic overhead (e. g. about 60% less in low mobility scenarios as shown in Fig. 3.4). Due to the way "provocative tracks" are established, the scheme has also the capability to adapt to the network traffic and mobility for a better performance. (2) To minimize the resource utilization of packet delivery in sparse MANETs where wireless links are intermittently connected, a store-and-forward based scheme, "adaptive multicopy routing", was developed for packet delivery in sparse mobile ad-hoc networks. Instead of relying on the source to control the delivery overhead as in the conventional multi-copy protocols, the scheme allows each intermediate node to independently decide whether to forward a packet according to the soft QoS target and local network conditions. Therefore, the scheme can adapt to varying networking situations that cannot be anticipated in conventional source-defined strategies and deliver packets for a specific QoS targets using minimum traffic overhead. ii (3) The important issue of mobility measurement that imposes heavy communication/computation burdens on a mobile is addressed with a set of resource-efficient "GPS-free" soluti ons, which provide mobility characterization with minimal resource utilization for ranging and signalling by making use of the information of the time-varying ranges between neighbouring mobile nodes (or groups of mobile nodes). The range-based solutions for mobility characterization consist of a new mobility metric for network-wide performance measurement, two velocity estimators for approximating the inter-node relative speeds, and a new scheme for characterizing the nodal mobility. The new metric and its variants are capable of capturing the mobility of a network as well as predicting the performance. The velocity estimators are used to measure the speed and orientation of a mobile relative to its neighbours, given the presence of a departing node. Based on the velocity estimators, the new scheme for mobility characterization is capable of characterizing the mobility of a node that are associated with topological stability, i. e. the node's speeds, orientations relative to its neighbouring nodes and its past epoch time. iiiBIOPATTERN EU Network of Excellence (EU Contract 508803

Integrated Architecture for Configuration and Service Management in MANET Environments

Esta tesis nos ha permitido trasladar algunos conceptos teóricos de la computación ubicua a escenarios reales, identificando las necesidades específicas de diferentes tipos de aplicaciones. Con el fin de alcanzar este objetivo, proponemos dos prototipos que proporcionan servicios sensibles al contexto en diferentes entornos, tales como conferencias o salas de recuperación en hospitales. Estos prototipos experimentales explotan la tecnología Bluetooth para ofrecer información basada en las preferencias del usuario. En ambos casos, hemos llevado a cabo algunos experimentos con el fin de evaluar el comportamiento de los sistemas y su rendimento. También abordamos en esta tesis el problema de la autoconfiguración de redes MANET basadas en el estándar 802.11 a través de dos soluciones novedosas. La primera es una solución centralizada que se basa en la tecnología Bluetooth, mientras la segunda es una solución distribuida que no necesita recurrir a ninguna tecnología adicional, ya que se basa en el uso del parámetro SSID. Ambos métodos se han diseñado para permitir que usuarios no expertos puedan unirse a una red MANET de forma transparente, proporcionando una configuración automática, rápida, y fiable de los terminales. Los resultados experimentales en implementaciones reales nos han permitido evaluar el rendimiento de las soluciones propuestas y demostrar que las estaciones cercanas se pueden configurar en pocos segundos. Además, hemos comparado ambas soluciones entre sí para poner de manifiesto las diferentes ventajas y desventajas en cuanto a rendimento. La principal contribución de esta tesis es EasyMANET, una plataforma ampliable y configurable cuyo objetivo es automatizar lo máximo posible las tareas que afectan a la configuración y puesta en marcha de redes MANET, de modo que su uso sea más simple y accesible.Cano Reyes, J. (2012). Integrated Architecture for Configuration and Service Management in MANET Environments [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/14675Palanci

An adaptive approach to service discovery in ad hoc networks

Service discovery allows the interaction between network nodes to cooperate in activities or to share resources in client-server, multi-layer, as well as in peer-to-peer architectures. Ad hoc networks pose a great challenge in the design of efficient mechanisms for service discovery. The lack of infrastructure along with node mobility makes it difficult to build robust, scalable and secure mechanisms for ad hoc networks. This paper proposes a scalable service discovery architecture based on directory nodes organized in an overlay network. In the proposed architecture, directory nodes are dynamically created with the aim of uniformly covering the entire network while decreasing the query latency for a service (QoS) and the number of control messages for the sake of increased scalability.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Application Layer Architectures for Disaster Response Systems

Traditional disaster response methods face several issues such as limited situational awareness, lack of interoperability and reliance on voice-oriented communications. Disaster response systems (DRSs) aim to address these issues and assist responders by providing a wide range of services. Since the network infrastructure in disaster area may become non-operational, mobile ad-hoc networks (MANETs) are the only alternative to provide connectivity and other network services. Because of the dynamic nature of MANETs the applications/services provided by DRSs should be based on distributed architectures. These distributed application/services form overlays on top of MANETs. This thesis aims to improve three main aspect of DRSs: interoperability, automation, and prioritization. Interoperability enables the communication and collaboration between different rescue teams which improve the efficiency of rescue operations and avoid potential interferences between teams. Automation allows responders to focus more on their tasks by minimizing the required human interventions in DRSs. Automation also allows machines to operate in areas where human cannot because of safety issues. Prioritization ensures that emergency services (e.g. firefighter communications) in DRSs have higher priority to receive resources (e.g. network services) than non-emergency services (e.g. new reporters’ communications). Prioritizing vital services in disaster area can save lives. This thesis proposes application layer architectures that enable three important services in DRSs and contribute to the improvement of the three aforementioned aspects of DRSs: overlay interconnection, service discovery and differentiated quality of service (QoS). The overlay interconnection architecture provides a distributed and scalable mechanism to interconnect end-user application overlays and gateway overlays in MANETs. The service discovery architecture is a distributed directory-based service discovery mechanism based on the standard Domain Name System (DNS) protocol. Lastly, a differentiated QoS architecture is presented that provides admission control and policy enforcement functions based on a given prioritization scheme. For each of the provided services, a motivation scenario is presented, requirements are derived and related work is evaluated with respect to these requirements. Furthermore, performance evaluations are provided for each of the proposed architectures. For the overlay interconnection architecture, a prototype is presented along with performance measurements. The results show that our architecture achieves acceptable request-response delays and network load overhead. For the service discovery architecture, extensive simulations have been run to evaluate the performance of our architecture and to compare it with the Internet Engineering Task Force (IETF) directory-less service discovery proposal based on Multicast DNS. The results show that our architecture generates less overall network load and ensures successful discovery with higher probability. Finally, for the differentiated QoS architecture, simulations results show that our architecture not only enables differentiated QoS, it also improves overall QoS in terms of the number of successful overlay flows

An adaptive approach to service discovery in ad hoc networks

Service discovery allows the interaction between network nodes to cooperate in activities or to share resources in client-server, multi-layer, as well as in peer-to-peer architectures. Ad hoc networks pose a great challenge in the design of efficient mechanisms for service discovery. The lack of infrastructure along with node mobility makes it difficult to build robust, scalable and secure mechanisms for ad hoc networks. This paper proposes a scalable service discovery architecture based on directory nodes organized in an overlay network. In the proposed architecture, directory nodes are dynamically created with the aim of uniformly covering the entire network while decreasing the query latency for a service (QoS) and the number of control messages for the sake of increased scalability.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Design and implementation of architectures for the deployment of secure community wireless networks

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/10251/10079Palanci

Supporting Large Scale Communication Systems on Infrastructureless Networks Composed of Commodity Mobile Devices: Practicality, Scalability, and Security.

Infrastructureless Delay Tolerant Networks (DTNs) composed of commodity mobile devices have the potential to support communication applications resistant to blocking and censorship, as well as certain types of surveillance. In this thesis we study the utility, practicality, robustness, and security of these networks. We collected two sets of wireless connectivity traces of commodity mobile devices with different granularity and scales. The first dataset is collected through active installation of measurement software on volunteer users' own smartphones, involving 111 users of a DTN microblogging application that we developed. The second dataset is collected through passive observation of WiFi association events on a university campus, involving 119,055 mobile devices. Simulation results show consistent message delivery performances of the two datasets. Using an epidemic flooding protocol, the large network achieves an average delivery rate of 0.71 in 24 hours and a median delivery delay of 10.9 hours. We show that this performance is appropriate for sharing information that is not time sensitive, e.g., blogs and photos. We also show that using an energy efficient variant of the epidemic flooding protocol, even the large network can support text messages while only consuming 13.7% of a typical smartphone battery in 14 hours. We found that the network delivery rate and delay are robust to denial-of-service and censorship attacks. Attacks that randomly remove 90% of the network participants only reduce delivery rates by less than 10%. Even when subjected to targeted attacks, the network suffered a less than 10% decrease in delivery rate when 40% of its participants were removed. Although structurally robust, the openness of the proposed network introduces numerous security concerns. The Sybil attack, in which a malicious node poses as many identities in order to gain disproportionate influence, is especially dangerous as it breaks the assumption underlying majority voting. Many defenses based on spatial variability of wireless channels exist, and we extend them to be practical for ad hoc networks of commodity 802.11 devices without mutual trust. We present the Mason test, which uses two efficient methods for separating valid channel measurement results of behaving nodes from those falsified by malicious participants.PhDElectrical Engineering: SystemsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120779/1/liuyue_1.pd