30 research outputs found
MESSAGE FERRY UNTUK DELAY TOLERANT NETWORK DENGAN ADAPTIVE ROUTE
Abstrak. Arsitektur jaringan Delay Tolerant Network (DTN) adalah sistem jaringan tanpa koneksilangsung antara source dan destination. Konsep dalam Delay Tolerant Network memiliki masapenundaan yang cukup tinggi, waktu antrian yang panjang, sumber daya yang terbatas dan koneksiyang terputus. Message ferry (MF) merupakan salah satu sumber daya yang digunakan dalam DTN.MF dapat menyediakan efisiensi pengiriman data karena dapat bergerak secara proaktif untukmenerima dan mengirim pesan sehingga dapat menurunkan penundaan. Penggunaan pemilihanroute dalam pengiriman paket data dapat memberikan hasil yang lebih optimal, seperti penggunaanalgoritma next hop. Namun algoritma tersebut dapat majadi masalah baru apabila node tujuantidak dapat menerima pesan yang dibawa oleh MF. Akan terjadi looping yang dapat peningkatandelay sehingga menurunkan efisiensi pengiriman. Dalam penelitian ini kami mengusulkan skemabaru untuk mengatasi permasalahan looping dengan menggunakan adaptive route agar dapatmenggurangi delay akibat dari kondisi pada node tujuan yang tidak dapat menerima pesan. Skemausulan kami beri nama dengan Adaptive Message Ferry Routing (AMFR).Kata kunci : Delay Tolerant Network, Message ferry, Adaptive Message Ferry Routing, algoritmanext hop
Exploring centrality for message forwarding in opportunistic networks
In opportunistic networks, centrality characterizes a node's capability to act as a communication hub. In this paper, we provide an in-depth study of choosing effective centrality metrics for message forwarding in bandwidth-limited opportunistic networks. Based on this study, we propose a destination-unaware forwarding algorithm that accounts for the popularity of a node and the contact durations between nodes. We evaluate the algorithm on two experimental human mobility traces. The simulation results show that the proposed algorithm achieves higher system throughput while maintaining a lower forwarding cost compared with several known destination-unaware forwarding schemes. ©2010 IEEE.published_or_final_versionThe 2010 IEEE Conference on Wireless Communications and Networking (WCNC), Sydney, NSW, Australia, 18-21 April 2010. In Proceedings of the IEEE WCNC, 2010, p. 1-
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Efficient and flexible geocasting for opportunistic networks
With the proliferation of smartphones and their advanced connectivity capabilities, opportunistic networks have gained a lot of traction during the past years; they are suitable for increasing network capacity and sharing ephemeral, localised content. They can also offload traffic from cellular networks to device-to-device ones, when cellular networks are heavily stressed. Opportunistic networks can play a crucial role in communication scenarios where the network infrastructure is inaccessible due to natural disasters, large scale terrorist attacks or government censorship. Geocasting, where messages are destined to specific locations (casts) instead of explicitly identified devices, has a large potential in real world opportunistic networks, however it has attracted little attention in the context of opportunistic networking. In this thesis, we propose Geocasting Spray And Flood (GSAF), a simple but efficient and flexible geocasting protocol for opportunistic, delay tolerant networks. GSAF follows a simple but elegant and flexible approach where messages take random walks towards the destination cast. Messages that follow directions away from the cast are extinct when the device buffer gets full, freeing space for new messages to be delivered. In GSAF, casts do not have to be pre-defined; instead users can route messages to arbitrarily defined casts. Also, the addressed cast is flexible in comparison to other approaches and can take complex shapes in the network. DA-GSAF as the direction aware version of the GSAF is proposed as well which use location information to aid routing decisions in the GSAF. Extensive evaluation shows that GSAF and DA-GSAF are significantly more efficient than existing solutions, in terms of message delivery ratio and latency as well as network overhead
Society Dissemination Based Propagation For Data Spreading In Mobiles Social Networks
In mobile ad hoc networks, nodes are dynamically changing their locations. MOBILE ad hoc networks (MANETs) consist of a collection of mobile nodes which can move freely. These nodes can be dynamically self-organized into arbitrary topology networks without a fixed infrastructure. A mobile ad hoc network consists of wireless hosts that may move often. Movement of hosts results in a change in routes, requiring some mechanism for determining new routes. Several routing protocols have already been proposed for ad hoc networks. MSNets can be viewed as a kind of socially aware Delay/ Disruption Tolerant Networks (DTNs). Thanks to the popularization of smart phones (e.g., iPhone, Nokia N95,and Blackberry), MSNets have begun to attract more attention. However, intermittent and uncertain network connectivity make data dissemination in MSNets a challenging problem. Broadcasting is the operation of sending data from a source user to all other users in the network. Most of the envisioned services (ranging from safety applications to traffic management) rely on broadcasting data to the users inside a certain area of interest. For example, location-based services (product prices, tourist points of interest, etc.) can be advertised from salesmen to near-by users. In this paper The objective is to broadcast data from a superuser to other users in the network. There are two main challenges under this paradigm, namely 1) how to represent and characterize user mobility in realistic MSNets; 2) given the knowledge of regular users' movements, how to design an efficient superuser route to broadcast data actively. We first explore several realistic data sets to reveal both geographic and social regularities of human mobility, and further propose the concepts of geocommunity and geocentrality into MSNet analysis
Zuverlässige Gruppenkommunikation in mobilen Ad-hoc-Netzen auf Basis eines verzögerungstoleranten Kommunikationsdienstes
Ein zuverlässiges Netz für die Kommunikation ist die Basis für eine erfolgreiche Organisation und Koordination von Rettungskräften in Katastrophenfällen. Die heutige Kommunikationstechnik der Rettungskräfte basiert auf dem digitalen Funksystem Terrestrial Trunked Radio (TETRA). TETRA bietet keine ausreichende Datenrate für Multimediadaten und ist bei zerstörter Infrastruktur nur eingeschränkt nutzbar. Deshalb ist es notwendig die Kommunikation in Katastrophenfällen auf anderen Netztypen aufzubauen und Protokolle weiterzuentwickeln.
Die vorliegende Arbeit befasst sich mit der zuverlässigen Gruppenkommunikation in Katastrophenfällen. Durch die oft fehlende Infrastruktur in solchen Szenarien, werden Mobile Ad-hoc Networks (MANETs) verwendet, um eine Kommunikation kurzfristig wieder herzustellen. MANETs bilden sich selbständig und sind in ihrer Reichweite eingeschränkt. Das kann dazu führen, dass mehrere zu einer Kommunikationsgruppe gehörende Kommunikationspartner nicht direkt miteinander verbunden sind. Um trotzdem eine Kommunikation zu ermöglichen, wurde unter Nutzung eines verzögerungstoleranten Kommunikationsdienstes (Delay Tolerant Networking (DTN)) ein Gruppenkommunikationsprotokoll entwickelt. Dieses Protokoll (Reliable Multicast over Delay Tolerant Mobile Ad Hoc Networks (RMDA)) übermittelt Gruppennachrichten mit einer hohen wählbaren Zuverlässigkeit an die gewünschten Gruppenmitglieder unter Optimierung des Speicherplatzbedarfs der DTN-Knoten.A reliable network for communication is the basis for a successful organization and coordination of rescue services in case of disasters. Today’s communication technology of the emergency services is based on the digital radio system Terrestrial Trunked Radio (TETRA). TETRA provides no sufficient data rates for multimedia data. In case of destroyed infrastructure it is available only to a limited extent. Therefore in case of disasters, it is necessary to provide communication services based on other network types and further development of protocols.
This thesis is concerned with reliable group communication in disaster scenarios. By the frequent lack of infrastructure in such scenarios, Mobile Ad-hoc Networks (MANETs) are used to restore quickly. MANETs build themselves autonomously and are locally limited. As a result, group members belonging to one multicast group could be not directly connected. Therefore, to enable a communication, a group communication protocol was developed using a delay-tolerant communication service (Delay Tolerant Networking (DTN)).
This protocol (Reliable Multicast over Delay Tolerant Mobile Ad Hoc Networks (RMDA)) sends group messages with selectable high degree of reliability to the desired group members, while optimizing the buffer required on the DTN nodes
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A novel Ferry Assisted Greedy Perimeter Stateless Routing Protocol (FA-GPSR) for Ad-hoc networks in remote locations
Network functionalities play a major role in the connectivity and routing in an Ad-hoc networks because end user devices must contribute in routing and therefore maintain connectivity. In dynamic environments with mobile nodes, routing becomes very challenging; this challenge becomes even more burdensome if a network is deployed in larger areas. Therefore, in order to avoid centralisation and bottlenecks, routing algorithms in Ad-hoc networks should not depend on any specific node. Furthermore, these algorithms should be able to support routing in sparse topologies when the density of the nodes is very low in a large deployment area. The rationale behind this research project stems from the lack of sufficiently effective solutions for wireless networks deployed in large areas where the node's mobility creates what is called the Loosely Coupled Nodes Problem. Therefore, this gap in knowledge needs to be addressed by developing a novel and scalable routing protocol, which can utilise application characteristics to stabilise routing between loosely coupled nodes in a large deployment area. This research proposes a new routing protocol to address this gap by increasing the number of packets delivered to their final destinations in an Ad-hoc networks. As another gap, very few current approaches deal with realistic situations, based on real-life case scenarios, in order to evaluate and enhance the accuracy of their Ad-hoc network protocols, and thus they cannot accurately approximate common real world environments [1]. Therefore, this project addresses research issues directly linked to evaluation of protocols and architectures in use cases and applications in real life scenarios. The novel routing algorithm, Ferry-Assisted Greedy Perimeter Stateless Routing (FA-GPSR), proposed in this thesis demonstrates the benefits of extracting information from the application to support communication between the nodes in the network topology. In addition, this approach highlights the advantages and disadvantages of the efficiency and reliability of communication in open large areas of deployment. A simulation model of the proposed algorithm has been implemented and its features investigated through simulation runs. The communication between nodes in the topology show that FA-GPSR outperforms the other routings in terms of packet delivery ratio, especially in sparse networks, where the density of nodes is low. The mobility of the destination nodes affected the packets delivery ratio by decreasing the ratio, compared to other cases because of the changes in the location and node velocity. By increasing the number of packets and source nodes, FA-GPSR outperformed the other algorithms because of the efficient use of the patrol node (ferry). Thus, the comparison of FA-GPSR to these algorithms supports the conclusion that FA-GPSR is suitable for use in large open areas with the effect of node density and packet load
Efficient Routing Protocol in Delay Tolerant Networks (DTNs)
Modern Internet protocols demonstrate inefficient performance in those networks where the connectivity between end nodes has intermittent property due to dynamic topology or resource constraints. Network environments where the nodes are characterized by opportunistic connectivity are referred to as Delay Tolerant Networks (DTNs). Highly usable in numerous practical applications such as low-density mobile ad hoc networks, command/response military networks and wireless sensor networks, DTNs have been one of the growing topics of interest characterized by significant amount of research efforts invested in this area over the past decade. Routing is one of the major components significantly affecting the overall performance of DTN networks in terms of resource consumption, data delivery and latency. Over the past few years a number of routing protocols have been proposed. The focus of this thesis is on description, classification and comparison of these protocols. We discuss the state-of-the-art routing schemes and methods in opportunistic networks and classify them into two main deterministic and stochastic routing categories. The classification is based on forwarding decisions in routing methods adopted with or without the knowledge about the network topology and nodes trajectories. The protocols in each class have their own advantages and shortcomings.
In the stochastic routing protocols category, simple flooding-based protocols are feasible approaches in those networks where there is a little or no information about the network topology and there is no resource restriction. Epidemic routing is a flooding- based protocol relying upon the distribution of messages through the networks to deliver information to their destinations.
To demonstrate the performance of the epidemic routing protocol for information delivery in networks with intermittent connectivities, we provide several simulation experiments and show that this protocol with reasonable aggregate resource consumption, ensures eventual message delivery in networks, using minimal assumptions regarding nodes trajectories, network topology and connectivity of underlying networks and only based on sufficient number of random pair-wise exchanges of messages among mobile nodes.
In the following, we introduce the recently proposed network coding concept and discuss coding-based information delivery advantages in wireless networks. Network coding is a recently introduced paradigm to efficiently disseminate data in wireless networks in which data flows coming from multiple sources are combined to increase throughput, reduce delay, and enhance robustness against node failures. Finally, we present some simulation experiments to show the superiority of network coding for information delivery in wireless networks, compared to pure flooding-based mechanisms. /Kir1
Self-organizing Network Optimization via Placement of Additional Nodes
Das Hauptforschungsgebiet des Graduiertenkollegs "International Graduate
School on Mobile Communication" (GS Mobicom) der Technischen Universität
Ilmenau ist die Kommunikation in Katastrophenszenarien. Wegen eines
Desasters oder einer Katastrophe können die terrestrischen Elementen der
Infrastruktur eines Kommunikationsnetzwerks beschädigt oder komplett
zerstört werden. Dennoch spielen verfügbare Kommunikationsnetze eine sehr
wichtige Rolle während der Rettungsmaßnahmen, besonders für die
Koordinierung der Rettungstruppen und für die Kommunikation zwischen ihren
Mitgliedern. Ein solcher Service kann durch ein mobiles Ad-Hoc-Netzwerk
(MANET) zur Verfügung gestellt werden. Ein typisches Problem der MANETs
ist Netzwerkpartitionierung, welche zur Isolation von verschiedenen
Knotengruppen führt. Eine mögliche Lösung dieses Problems ist die
Positionierung von zusätzlichen Knoten, welche die Verbindung zwischen den
isolierten Partitionen wiederherstellen können. Hauptziele dieser Arbeit
sind die Recherche und die Entwicklung von Algorithmen und Methoden zur
Positionierung der zusätzlichen Knoten. Der Fokus der Recherche liegt auf
Untersuchung der verteilten Algorithmen zur Bestimmung der Positionen für
die zusätzlichen Knoten. Die verteilten Algorithmen benutzen nur die
Information, welche in einer lokalen Umgebung eines Knotens verfügbar ist,
und dadurch entsteht ein selbstorganisierendes System. Jedoch wird das
gesamte Netzwerk hier vor allem innerhalb eines ganz speziellen Szenarios -
Katastrophenszenario - betrachtet. In einer solchen Situation kann die
Information über die Topologie des zu reparierenden Netzwerks im Voraus
erfasst werden und soll, natürlich, für die Wiederherstellung mitbenutzt
werden. Dank der eventuell verfügbaren zusätzlichen Information können
die Positionen für die zusätzlichen Knoten genauer ermittelt werden. Die
Arbeit umfasst eine Beschreibung, Implementierungsdetails und eine
Evaluierung eines selbstorganisierendes Systems, welche die
Netzwerkwiederherstellung in beiden Szenarien ermöglicht.The main research area of the International Graduate School on Mobile
Communication (GS Mobicom) at Ilmenau University of Technology is
communication in disaster scenarios. Due to a disaster or an accident, the
network infrastructure can be damaged or even completely destroyed.
However, available communication networks play a vital role during the
rescue activities especially for the coordination of the rescue teams and
for the communication between their members. Such a communication service
can be provided by a Mobile Ad-Hoc Network (MANET). One of the typical
problems of a MANET is network partitioning, when separate groups of nodes
become isolated from each other. One possible solution for this problem is
the placement of additional nodes in order to reconstruct the communication
links between isolated network partitions. The primary goal of this work is
the research and development of algorithms and methods for the placement of
additional nodes. The focus of this research lies on the investigation of
distributed algorithms for the placement of additional nodes, which use
only the information from the nodes’ local environment and thus form a
self-organizing system. However, during the usage specifics of the system
in a disaster scenario, global information about the topology of the
network to be recovered can be known or collected in advance. In this case,
it is of course reasonable to use this information in order to calculate
the placement positions more precisely. The work provides the description,
the implementation details and the evaluation of a self-organizing system
which is able to recover from network partitioning in both situations